Paleoimaging: Field Applications for Cultural Remains and Artifacts

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Paleoimaging

Ronald G. Beckett Quinnipiac University Hamden, Connecticut, USA

Gerald J. Conlogue Quinnipiac University Hamden, Connecticut, USA with a Foreword by

Andrew J. Nelson, Ph.D.

Boca Raton London New York

CRC Press is an imprint of the Taylor & Francis Group, an informa business

CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2010 by Taylor and Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number: 978-1-4200-9071-0 (Hardback) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright.com (http:// www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Beckett, Ronald G. Paleoimaging : field applications for cultural remains and artifacts / Ronald G. Beckett, Gerald J. Conlogue. p. cm. Includes bibliographical references and index. ISBN 978-1-4200-9071-0 (hardcover : alk. paper) 1. Imaging systems in archaeology. I. Conlogue, Gerald J. II. Title. CC79.I44B43 2010 930.1--dc22 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com

2009028071

Dedication

Since this text is the culmination of over 40 years as a radiographer, the ἀrst dedication is to those radiographers, Ray Gagnon, Marty Ricart, Bob Pooler, and Charlie Maccalous, who were not only my teachers, demonstrating the science and art of radiography, but also instilled the spirit that anything is possible. To Drs. E. Leon Kier and John Ogden, who taught me how to formulate and carry out research. To the late Dr. Tony Bravo, who showed me not only courage in the face of death, but also how to enjoy life. To my son Byron, his wife Nicole, my daughter Keanau, and my son Michael, who continue to be very accepting of my eccentricities. Last, but certainly not least, to Shar Walbaum whose encouragement, conἀdence, and belief in my pursuits are ultimately responsible for my success and this book. Gerald Conlogue This book is further dedicated to those many individuals who have helped me to develop not only my endoscopic skills but also those who have enhanced my understanding of pathophysiology among the living. LeRoy Johansen, Steven McPherson, Bud Spearman, Robert Kaczmarek, Dean Hess, and Harold McAlpine, who collectively showed me how to be a respiratory therapist, to never be satisἀed with the status quo, and provided a model to follow in research and scholarly work. To Drs. William Ludt and Michael McNamee, who constantly challenged my understanding of clinical medicine and disease states and encouraged me to know more. To Ralph “Buster” Beckett whose early 20th century work in agricultural research sparked my desire to understand the world around me. To my parents, Howard and Terry & Beckett, who taught me how to “play in the sand”, no matter how old I was. To my sons Matthew, Paul, and James, and my daughter Julie, who have been so very supportive of my interests and efforts and from whom I have and continue to learn so much. And to my wife Katherine Harper-Beckett, who has supported not only this project but held me up on so many occasions with her quite strength and sincere belief in me. I am forever blessed. Ronald Beckett

Table of Contents

Foreword Preface Acknowledgments Contributing Author

ix xi xvii xix

Section I Paleoimaging Multimodalities

1

Photography for Paleoimaging

3

Ronald Beckett and Gerald Conlogue

2

Conventional Radiography

19

Gerald Conlogue and Ronald Beckett

3

Computer-Based Imaging

123

Gerald Conlogue, Ronald Beckett, and John Posh

4

Endoscopy: Field and Laboratory Application of Videoendoscopy in Anthropological and Archaeological Research

185

Ronald Beckett and Gerald Conlogue

Section II Paleoimaging Standards

5

Radiographic Procedures and Standards

233

Gerald Conlogue and Ronald Beckett

6

Endoscopic Procedures and Standards Ronald Beckett and Gerald Conlogue

vii

245

viii Table of Contents

Section III Artifact Analysis

7

Paleoimaging the Internal Context

265

Ronald Beckett and Gerald Conlogue

8

Paleoimaging the External Context

293

Ronald Beckett and Gerald Conlogue

9

Paleoimaging Objects Out of Context

311

Gerald Conlogue and Ronald Beckett

Section I V Safety in the Field Setting

10

Field Paleoimaging Safety and Health Challenges

339

Ronald Beckett

11

Radiation Protection and Safety

355

Gerald Conlogue

Appendices Appendix A: Recording Form for Radiographic Examination of Mummified or Skeletal Remains and Artifacts

365

Appendix B: Recording Form for Endoscopic Examination of Mummified or Skeletal Remains

369

Appendix C: Example of Risk Assessment Documentation

373

Appendix D: Expedition Kit List—Papua New Guinea

385

Appendix E: Statement of Health

387

Index

391

Foreword

Archaeology is necessarily a destructive science, as the very process of excavation involves the removal of objects from their original context; however, the archaeological team seeks to maximize the nondestructive recovery of information at every step along the way from discovery, to analysis, to conservation. The capture of images of cultural remains and artifacts—paleoimaging—is central to that process. In this book, Beckett and Conlogue call upon their considerable hands-on experience to provide an in-depth examination of the three most important imaging techniques, photography, radiography, and endoscopy, and explain how these techniques can be applied to all aspects of archaeological and artifactual analysis. Other authors have touched on individual aspects of this subject matter, but this is the first volume to provide the rationale and methodology for each technique and to synthesize them in one place. As such it is a tremendously valuable resource. There are several significant themes that run throughout this volume that are worth emphasizing in this foreword. They are the importance of teamwork, the concept of multimodal imaging, and the effective use of technology. I will address these themes in sequence.

Teamwork Archaeology, from prospection to excavation, to analysis, to conservation, to exhibition, is a multidisciplinary undertaking that requires coordinated contributions from many people with many different skill sets. Beckett and Conlogue highlight the paleoimaging team, consisting of paleoimagers and paleoimaging interpreters; however, they make the observation that there are very few people who are specialized in either area. Thus, this volume plays an extremely important role in developing the paleoimaging team, as it provides a common language that radiologists, archaeologists, biological anthropologists, and radiological technicians can use. A common language leads to effective communication and helps coordinate efforts to achieve a common goal.

Multimodality Beckett and Conlogue emphasize the term multimodal imaging, suggesting that each imaging technique adds new elements to the process of information recovery. Unfortunately, many archaeologists are not familiar with radiography or endoscopy, so these techniques are underutilized in the discipline. This volume provides clear explanations of the value of each imaging modality as well as the equipment required and the methods utilized. Thus, it will play an important role in expanding the analytical horizons of archaeologists everywhere. Beyond the basics of each imaging modality an equally important contribution of this volume is its emphasis on creativity in terms of how the modalities are deployed. For instance, there are very few radiological technologists who would think of taking a ix

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clinically obsolete x-ray machine to the field, to power it using generators and converters, and to set up a dark room in a tent. Likewise, not many pulmonologists would think of lowering their endoscopes into unopened tombs. Beckett and Conlogue are masters at the creative application of their skills and equipment; they are genius lateral thinkers, and they are the consummate problem solvers. The reader who pays particular attention to this creativity will get the most out of this volume.

Effective Use of Technology Mummies have been front and center in the imaging world from the time of the discovery of x-rays and through every advance in radiological technology. The recent arrival of the latest 256 slice CT scanner in a U.S. hospital was celebrated by scanning a mummy as the first “patient.” The appeal of “high tech” has led to the common perception that other methods of imaging have become obsolete. However, nothing could be further from the truth. As Beckett and Conlogue ably demonstrate, simple equipment can be utilized to capture vital information, particularly in field situations. Furthermore, a familiarity with basic imaging techniques is a requirement to fully understand and exploit the advanced capabilities of digital imaging. Thus, newer is not necessarily better, and the most effective paleoimaging team will consider all available imaging methods.

Beckett and Conlogue There are no two scholars who are better qualified to write this book. I can attest from personal experience that there are no others I would rather have on a field project. I have seen first-hand their teamwork ethos, their creativity and adaptability, and their ability to use the simplest equipment to the maximum effect. They have traveled the world x-raying and endoscoping mummies of commoners, monks, and saints; they have imaged Peruvian whistling pots, Chinese porcelain vases, and sideshow curios; they have worked in tombs, labs, and museums, and they have communicated the results of their work in the popular media, in the classroom, and in scholarly works. This volume is a compendium of a vast body of personal experience and two lifetimes dedicated to bringing their skills and enthusiasm to the service of archaeology. This book will find a prominent place on the shelves of archaeologists, anthropologists, radiological technicians, physicians, museologists, conservators, and interested individuals from many other walks of life. Andrew J. Nelson, PhD Bioarchaeologist Associate Professor of Anthropology University of Western Ontario London, Ontario Research Associate Royal Ontario Museum Toronto, Canada

Preface

Background and Rationale Medical and industrial imaging methods have the potential to be powerful tools in both the documentation and data collection procedures found in many nontraditional settings. Each technology described in this text has been applied to alternate settings, such as mummified human remains, soon after its historical development. In addition to providing useful data for analysis, these powerful tools have the added benefit of being nondestructive, thereby preserving the remains or artifacts for future analysis with yet to be developed technologies. The authors began this work to provide a basis for understanding the field application of various imaging modalities in bio-anthropological settings. However, these imaging modalities have also been applied in studies of non-biological specimens. Section III, Artifact Analysis, has been included to present the broader application potential of these imaging methods. An array of imaging methods has been employed in anthropological and archaeological research. When applied individually, certain information can be obtained. When applied in a complementary manner, not only can additional data be collected, but also the relationships among those data may often enhance our understanding of the meaning of their associations. In the recent past, literature referred to the use of a single imaging method or modality, such as x-ray, endoscopy, or computed tomography (CT) scans. More recently, scientific papers and presentations have adopted the term multimodal imaging. Since each modality has advantages and disadvantages, most researchers support the construct that no single modality can obtain all the data possible from a given subject. Therefore, multiple imaging methods need to be applied in an attempt to maximize data collected and to enhance the interpretability of those data. Conventional, or standard x-rays (radiographs), yield a two-dimensional image of three-dimensional objects. In addition, the images have the associated problems of superimposition of shadows, an inability to differentiate structures of similar densities, magnification, and distortion. Without creative application technique a standard x-ray cannot provide data describing the true spatial relationship of an object or organic feature within the broader context of the body as a whole. Conventional radiography does, however, have the potential to be highly portable and can yield much information that would be otherwise unobtainable. Radiography is ideally suited for the field research environment. Endoscopy can complement the radiograph, providing an image with shape, contour, color, and location of what was only a shadow on the x-ray. Additionally, the endoscope can be used to guide instruments for retrieval of tissues or artifacts from within a closed environment, such as a body cavity, coffin, or tomb. The instrumentation is portable and well suited for field imaging studies. xi

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If the subject of the study can be moved, computed tomography (CT) could be employed to better reveal the spatial relationships within the subject. The CT scan can also guide biopsy or artifact retrieval procedures. Although “portable” CT scanners exist, their size and the logistics of terrain often result in limited availability in remote field settings. In addition, the hardware and software of these units place limitations on the type of data obtainable. The data collected by the more recently introduced multidetector CT (MDCT) scanner, once stored, can be reformatted to view the study object from multiple planes and generate 3-D representations of those data. The 3-D image can be of the object as a whole or feature a single organ, structure, or artifact associated with the subject. The data may also be animated to rotate the object for multi-directional viewing and analysis. Computed radiography (CR) and direct digital radiography (DR) have the advantage of being filmless systems that allow manipulation of the displayed image to improve the image exposure, possibly revealing otherwise “invisible” structures. Since CR and DR generate 2-D images, superimposition of shadows and many of the other disadvantages associated with conventional radiography are still problematic. Magnetic resonance imaging (MR) has also found its way into the anthropological arena and adds data otherwise unobtainable by the other mentioned modalities. Unlike the other modalities described, x-rays are not involved in the production of MR images. High intensity magnetic fields are manipulated to, most commonly, measure the “mobile” hydrogen content of the object under investigation. Like the CT instrumentation, MR imaging requires the study subject to be brought to an imaging or research facility. Photographic documentation and analysis is another mode applied in the paleoimaging setting. Standard and filtered photographs allow for continued indirect visual analysis once the researcher has departed the original research site. Newer photographic methods can produce 3-D representations of surface characteristics allowing the researcher to view surface features from various angles. Each of the tools in the multimodal-imaging arsenal comes with its unique application limitations. For example, CT scanners are quite large and weighty, making them difficult to apply in field or remote settings. Additionally, CT scans have the potential to produce tremendous numbers of images, many of which contribute little to the study. Endoscopy requires an access route. Conventional or computed radiography, while portable, produces 2-D images. The use of the term multimodal therefore indicates the natural evolution of imaging in anthropological and archaeological research, moving from specific single modality imaging studies to those that incorporate several imaging methods. Collectively, multimodal imaging, when applied to anthropological and archaeological research, has come to be known as “paleoimaging.” The term paleo refers to studies involving ancient, prehistoric, primitive, or early structures or cultures. However, the term paleoimaging has been generalized to a broader context to include not only prehistoric subjects but also the analysis of historic human or animal remains, associated artifacts, and in archaeological applications. The data collected through paleoimaging methods have been applied using both the medical approach, where the study subjects are transported to an imaging facility and, in contrast, the anthropological approach, where the subjects are examined in or very near the original context. In anthropological and archaeological research context is critical. The burial location, relationship and position of objects, and burial goods are all critical data requiring analysis within or as close to the original context as possible. Once an object, such as mummified

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human remains, is moved, the context is altered. Not only the relationship among related objects, buildings, and tombs, but what is held within a mummy bundle or within the mummy itself, too, can be disturbed, further altering the internal context. Whenever possible, researchers would do well to employ in context field imaging methodology for initial data collection. In context field imaging demonstrates the nondestructive nature of the described modalities and is the main focus of this book. Once the object is moved from its original context, the nondestructive nature of a study is jeopardized. The actual act of moving the object may in fact be destructive. If the use of advanced imaging, such as a CT scan, is warranted, the decision to transport the subject to an imaging facility needs to be based upon the safety of the study subject and what additional data the advanced imaging may add to the case at hand. If on-site field imaging is conducted, those data can contribute to the risk/ benefit decision of whether or not to move the object for more advanced imaging.

Standards: Methods and Procedures Another critical issue surrounding paleoimaging research is that of methodological and procedural standards. Many reports in the literature often omit specific details regarding technical factors, such as radiographic exposure settings, data recording media, specific instrumentation, or endoscopic lenses used as related to the imaging data collected. Another issue is that many who are new to the paleoimaging arena may be experienced at gathering data and interpreting images produced from living subjects but not from mummified remains. Mummies, for the most part, are completely desiccated. The desiccation process, as well as many artificial preparation procedures creating that mummy, alters the manner in which imaging data can be attained for maximal interpretability. Collecting images that call for a new exposure setting or positioning approach may not be considered due to a lack of experience in operating the equipment in archaeological or anthropological contexts. Interpretation, too, can be challenging to the untrained eye. The morphologic changes seen in organ systems among the varied mummification processes, for example, may lead to misinterpretation of the significance of structures by someone who is accustomed to interpreting images from hydrated, living patients. In Paleoimaging: Field Applications for Cultural Remains and Artifacts, Section II, Paleoimaging Standards, the authors offer application standards for the varied imaging modalities as applied to this specific line of research. The methodological and procedural standards offered in this text are intended to assist researchers in obtaining the desired data in an accurate, efficient, and reproducible manner.

Artifact Imaging The paleoimaging techniques described in this text have a natural application in the imaging of non-biological cultural artifacts. Section III, Artifact Analysis, of Paleoimaging: Field Applications for Cultural Remains and Artifacts demonstrates how multimodal imaging can assist nondestructive data collection in an archaeological context. Imaging applications to help discover such variables as ceramic construction and technology complexity, orientation and composition of grave goods, temporal context based on artifact analysis,

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differentiation between authentic and fraudulent artifacts, and imaging works of art for conservation purposes are described.

Safety in Field Paleoimaging Projects Radiation safety and field safety concerns presented in Section IV, Safety Concerns in the Field, describe the application and situational variables that will allow safe data collection in challenging field settings. The radiation safety and field safety discussions are intended to provide those involved in field imaging projects with the basic understanding of the safety issues at hand as well as practical means of preparing for and conducting paleoimaging studies in a safe and responsible manner.

The Paleoimaging Team—A Brief Discourse Bioanthropological and bioarchaeological research naturally calls upon the skills of various scientists from many disciplines. Among those disciplines are those individuals skilled in paleoimaging. When considering the data attainable from the varied imaging studies applied to the anthropological and archaeological setting, several variables need to be considered: the data collection or paleoimaging process, recalibration of those processes for additional data collection, and the interpretation of these data. It would seem logical then that to conduct such research one would need someone to collect the data, a paleoimager, and someone to interpret the data. While this may seem straightforward, it is the opinion of the authors that the researchers filling these roles should have special qualifications. Paleoimagers (Data Collectors) Paleoimagers need to be experienced in the examination of naturally and intentionally mummified animal and human remains, and various types of artifacts. Collecting the data requires skills related to radiographic exposure settings, positioning, familiarity with morphologic variations seen associated with varied mummification methods, recording media, and data collection manipulation skills. These skills should also include an understanding of what data need to be collected given the research objectives and with careful consideration of the context. For example, setting the exposure variables and selecting the type of film and film holder to image the bony skeleton within a mummy bundle would likely not visualize desiccated organ remnants inside the mummy. Exposure variables set to pick up features of the integument would also reveal features of the wrappings. Knowing when and how to use imaging modalities to best acquire the desired images requires creativity and skillful application of the many exposure and positioning variables. Additionally, the individual must possess the skills and knowledge necessary to override preset protocols built into the software of sophisticated instrumentation designed to image living hydrated patients in medical settings. It is, therefore, a combination of skills required that are associated with the practice of radiography, coupled with knowledge of anthropological variations and the significance of nuances in the data collected. A paleoimager, as it relates to radiographic data collection, should be a radiologic technologist who has been mentored by a seasoned field paleoimager and bioanthropologist as there are no

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current preparation programs for this growing field. The individual needs to be trained in multiple modalities, the medical and industrial applications of those modalities, and well versed in the limitations of each modality. Further, the individual needs to be an expert in cross-sectional anatomy and be familiar with pathological conditions and the signs those conditions may leave behind in mummified tissue. Another required attribute is that the individual be technically adept and creative as much of the research is conducted in remote areas without reliable electricity sources or water, thus requiring instrument modification adapting to the given situation. Critical thinking is paramount. Endoscopic data collection needs to be conducted by an individual familiar with the many technical variables associated with these procedures. The individual needs to have a working knowledge of the instrumentation possibilities including both medical and industrial tools. Media archiving skills are also important. Biopsy techniques and artifact retrieval skills are necessary as these techniques are often specific to the research objectives. An understanding of anatomy and physiology is critical as is the understanding of pathological changes in organs and tissues. Further, an understanding of the varied morphologic changes seen among various mummification practices is vital. This paleoimager, too, must be creative and adaptive to the varied research environments. In addition to the knowledge and skill base described, a seasoned field endoscopist and a bioanthropologist should mentor the individual in order to maximize the application of this modality. The importance of photographic documentation of paleoimaging research cannot be understated. The photographer need not only be an expert in photographic methods but also be well aware of what is critical information to document. Typically, the photographer is under the direction of the project coordinator, usually an anthropologist or bioarchaeologist. However, the ideal photographer would know what to photograph and when to photograph and blend in naturally with the workflow. The photographic documentation required includes, but is not limited to, contextual documentation, procedural documentation, scientific documentation, and an artful representation of the remains or artifacts under investigation.

Paleoimaging Interpreters Initially, it would seem that since much of the data collected is radiographic, a radiologist would be the logical individual to make the interpretations. While this may be true, there are very few true paleoradiologists available. In fact, there are no specialized training programs in this area of expertise. Too often a radiologist becomes a paleoradiologist as soon as she/he interprets her/his first mummy x-ray. Sadly, this oversimplifies the challenges faced in the interpretation of images produced from mummified human remains. The radiologist does possess the skills necessary for interpretation when the subjects are living hydrated patients. However, the morphologic changes seen among the varied mummification practices require the radiologist to be well versed in the processes of mummification and their effects on the human body. While the radiologist’s skills involving differential diagnosis are critical to the interpretation of data, the analyses should include consultation with a physical anthropologist, bioanthropologist, or bioarchaeologist as well as a paleopathologist. It is only with this expert input regarding such variables as cultural practices surrounding the mummification method, dietary habits of the culture, and knowledge of varied environmental impacts on human tissue over time, that differential diagnoses

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can more accurately be determined. The paleoimaging interpreters, then, should include the radiologist (mentored by bioanthropology, bioarchaeology, physical anthropology, and paleopathology), along with a bioanthropologist, physical anthropologist and/or a bioarchaeologist, and a paleopathologist who is well versed in imaging modalities. In summary, the ideal paleoimaging team would include a photographer, a radiographer, an endoscopist, a radiologist, a bioanthropologist or bioarchaeologist, a physical anthropologist, and a paleopathologist, all of whom would have specialty training and experience in the process of human mummification and its morphologic and taphonomic impact on the remains. Additional medical experts such as trauma physicians, orthopedists, pulmonary specialists, and dentists, as well as many others, should be available to enhance the interpretation of those data related to their area of expertise.

Summary Paleoimaging: Field Applications for Cultural Remains and Artifacts is a work intended to describe the strengths and limitations of imaging applications in varied nontraditional field settings. The text offers methodological and procedural standards for the application of these modalities as well as standards for interpretation of the collected data. The authors hope that this text will contribute to those researchers who desire to employ paleoimaging in their research projects. The text intends to contribute to the growing field of mummy science studies. The potential contribution of this work rests in the concept that the interpretation and understanding of ancient cultures can only be as good as the data collected.

Acknowledgments

All paleoimaging work is teamwork. We are fortunate to have been invited to collaborate on a great many research endeavors around the globe. A book like this would not have been possible without the assistance of a great number of individuals, private imaging facilities, and institutions. We need to acknowledge many researchers and colleagues from whom we have learned so very much about the exciting “time travel” we all get to experience through our common interests. In no particular order and our apologies to those inadvertently omitted: Mütter Museum: Gretchen Worden; Quinnipiac University: Joseph Woods, William Hennessy, Dennis Richardson, Tania Blyth, Jiazi Li, and Derik Weber; researchers in bioarchaeology and paleopathology: Gino Fornaciari, Anthony Bravo, Bob Brier, Roxy Walker, Andrew Nelson, Roger Colton, Janet Monge, Lisa Schwappach, Sonia Guillen, Bernardo Arriaza, Arthur Aufderheide, Larry Cartmell, and Alana CordeCollins; Slater Memorial Museum, Norwich Free Academy, Norwich, Connecticut; Susan Frankenbach, Vivian F. Zoe, and Alexandra Allardt; Advance Radiology Consultants, Fairfield, Connecticut: Monique LeHardy, Amy Kovac, Andrea Mel, and Dennis Condon; Barnum Museum: Kathy Maher; Toshiba American Medical Systems: Mark Hatin; Madison Radiology, Old Lyme, Connecticut: Anne Stebbins; Auman Funeral Home: Gary Double; Zoom Imaging: John Posh; Naugatuck Valley Associates: Dave Votto; Ripley’s Believe it or Not®: Edward Meyer and Barry Anderson; FUJIFILM NDT Systems: Bob Lombardo; University College, Dublin; Engel Entertainment (formerly Engel Brothers Media); National Geographic Channel (U.S.); National Geographic Channel International; Paleopathology Association; Yale Peabody Museum of Natural History; and Rosicrucian Egyptian Museum. Ronald Beckett and Gerald Conlogue

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Contributing Author and Reviewers

John Posh, RT (R), (MR)

Chief Veterinary MRI Technologist MRI Safety Officer Animal Scan LLC Senior Partner MRI Safety Specialist Bethlehem, Pennsylvania

Reviewers William F. Hennessy, MHS, RT (R), (M), (QM), OAP(C) Chairman, Department of Diagnostic Imaging Program Director of Diagnostic Imaging Assistant Professor of Diagnostic Imaging Quinnipiac University Hamden, Connecticut

Shelley L. Giordano DHSc, RT(R), (MR) Director of Academic and Clinical Coordination Graduate Radiologist Assistant Program Assistant Professor of Diagnostic Imaging Quinnipiac University Hamden, Connecticut

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I

Paleoimaging Multimodalities Introduction: Getting Started

The use of the term multimodalities is fairly self-explanatory when applied to paleoimaging. The term simply means using more than one imaging modality to derive the most usable data in an attempt to make accurate interpretations regarding past peoples and their cultures. Using the multimodal imaging approach in anthropology and archaeology is much like gathering evidence for a forensic case. The more evidence you have to support the suppositions as they relate to the case, the stronger the case. Unfortunately, no single imaging modality can give you all the information you need. In fact, relying on a single imaging modality may increase the incidence of misinterpretation. As is the case with all research, any new data acquired should give rise to many more questions. In paleoimaging, general questions arise from a data point derived from a single imaging modality and may include the following: How can we confirm what we think we are seeing? How can we use additional imaging to better inform our interpretations? Sometimes, the answer is the reapplication of that imaging mode, perhaps from a new projection angle. In other cases, the answer lies in using additional imaging methods to clarify and confirm the original data. Although more advanced imaging, such as computed tomography, is a useful approach to additional data collection, often conditions in field settings and the condition of human mummified remains or artifacts limits the transportation possibilities and, thereby, the application of additional imaging modes. Field settings often present situations in which there are limited resources. In these cases, the creativity of the paleoimaging team comes into play. Skilled paleoimagers who can apply the constructs of critical thinking, using what resources is available, are often able to collect additional applicable data that assist in the interpretation of the collected data. Also, using portable and complementary imaging modalities in the field can generate a tremendous amount of data for those interpretations. The paleoimaging multimodalities that have proved useful in anthropological and archaeological research are addressed in the first section of this book. These modalities include photographic techniques; conventional radiography; computerized imaging, such as computed radiography, direct radiography, computed tomography, and magnetic resonance; and varied endoscopic techniques. These imaging tools create a powerful means of collecting accurate data with little or no damage to the mummified remains or artifacts. Multimodal imaging, therefore, preserves the study subjects for future researchers using yet-to-be-developed data collection instrumentation. Although not all of the imaging modalities discussed in this section can be readily applied in the field, several can. Paleoimaging conducted at or near the original context has the potential to gather the most accurate imaging data as moving the study subject may create an alteration of the internal context, that is, the context within the mummy itself. In addition, 1

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

data analysis in context enhances the ability of researchers to make crucial connections between and among the imaging data and the cultural setting, including burial inclusions. This section includes four chapters that introduce the reader to paleoimaging multimodalities including photography, conventional radiography, computerized imaging modalities, and endoscopy. The field applications and limitations of each modality are presented, and case examples are used when appropriate.

Photography for Paleoimaging

1

Ronald Beckett and Gerald Conlogue Contents Introduction Context Establishing Workflow Documenting Procedures Evidentiary Special Photographic Techniques Summary References

3 4 8 9 15 16 16 17

Introduction The relationship between photography and anthropology has been well established over many years. Before improvements in communications, photographs were how anthropologists and archaeologists could bring exciting and new information to Western cultures. Photographs were used by these disciplines to promote their work and to share scholarly information among the academic community (Edwards 1992). Photography was first used to simply present portraits of peoples or of landscapes, providing a context for those viewing the images. Soon, photography in anthropology came to be used as an instrument of representation (Collier and Collier 1986). Anthropology used photography in a methodological and prescribed manner. The intent was to document field findings with scientific objectivity. Today, many anthropologists and researchers from other disciplines, such as paleoimagers, have had little or no formal training in photography and assume that photography is a simple manner of point and shoot. However, when building a team for a field research project, current practice is to strive to engage trained photographers in order to provide accurate, complete, and usable images. The photographs are then combined with a narrative or text provided by the field anthropologist and other specialists to ensure that any photographs taken have a purpose beyond objectifying the subject. In this way, the field context can be captured and better communicated. Each discipline brings its special knowledge and skills to bear on a field research project. Photographers, too, have their place in fieldwork. Additionally, the continued development of digital photographic technology makes on-site instant image review possible. We begin this section with a chapter on photography because in paleoimaging research, we begin each procedure with direct visual observation. Photography, if conducted with skill, has the potential to augment our observational skills. It is beyond the scope of this chapter to delve deeply into the technologies and techniques of trained photographers. Nor do we intend to explore the philosophical aspects of field photography. Rather, it is the 3

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intent of this chapter to establish the importance of photography in relation to paleoimaging studies. On many occasions, reviewing paleoimaging data, such as radiographs and endoscopic images, after their initial collection provides the researchers an opportunity to examine those images in greater detail. The additional study of the images often results in finding features initially overlooked that are important to the case at hand. This is true for photography as well. The photograph can provide a wealth of information that is sometimes missed during the initial visual observation. The photographer should be a full member of the paleoimaging team. As the reader will see through the remainder of this chapter, the photographer will have specific required tasks intended to complement the paleoimaging study. The photographer should be well versed in the characteristics, requirements, operation, and limitations of the paleoimaging technologies employed. The photographer needs to be aware of the photographic requirements of the other paleoimaging team members. Additionally, the photographer should be adept at various photographic methods including filtered photography, macrophotography, scientific photography, and low-light photography. The photographer must also possess an understanding of the ancient cultural aspects of the particular study, which will serve to inform him or her about what is critical to document. Photography’s use as an adjunct to paleoimaging is less concerned with its place in visual anthropology and more focused on evidentiary documentation of subject, context, procedure, and modifications. This represents an objective application of photography rather than using as a tool to elicit some type of deep human response. With that said, photography as one of our multimodal tools in paleoimaging provides not only the scientific documentation required but also images that can move the heart.

Documenting Context The first role of photography as it relates to paleoimaging is to document the physical setting where the research will be conducted. The general environment associated with the study at hand should be photographed with respect to those environmental features that may impact the work to be done. In addition, the context from where the cultural remains or artifacts came is critical, as it may assist in the interpretation of paleoimaging data. The environmental conditions may help explain taphonomic characteristics of the cultural remains as artifacts and human and animal remains continue to interact with their environment over time (Aufderheide 2003; Figure  1.1). These photographs may include documentation of nearby waterways; urban sprawl; evidence of flood plains, landslides, or cave-ins; and documentation of current climatic characteristics, to name a few. Photographs of where the cultural material was found are also critical, as often a microclimate exists that can further explain the condition of the remains or artifacts. These photographs may include tombs, a cliffside, or other burial aspects such as wrappings and enclosures (Figures  1.2–1.5) that may have impacted mummification or the state of preservation of the remains. If radiographic or endoscopic images are later transported to specialists in other countries, photographs of the regional environmental conditions and the specific burial sites may be critical in interpreting what is seen on the paleoimaging data.

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Figure 1.1  (See color insert following page 12.) Photographs of regional environments that

may impact the mummification and preservation of cultural artifacts and remains. Shown here is a dry desert environment (left) and modern agriculture near ancient burial tombs (right) that may impact the water table.

Of equal importance is the photographic documentation of the specific paleoimaging environment, where the work is to be conducted. On many occasions, field paleoimaging is conducted in very tight settings such as in caves, tombs, and remote research facilities. Photographic documentation of these variables not only provides a record of the working conditions but also may assist future researchers who are planning a field paleoimaging project in the same or similar environment. Photographic documentation

Figure 1.2  (See color insert following page 12.) Photographic documentation of a subterranean tomb environment that may explain paleoimaging data.

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Figure 1.3  Photographic documentation of the opening to a cave that holds mummified Ibaloi remains in the Kabayan Jungle, Luzon, the Philippines.

of how logistical challenges were resolved is also a useful information to future research teams (Figure 1.6). Any feature of the environmental setting that may pose a safety risk should be photographed as well. Paths, walkways, stairs, ladders, streams, electrical supply outlets, and generators are just a few examples of what should be photographed in order to document the challenges and adaptations used to get the paleoimaging project under way. Following the documentation of context, the subjects of the study should be photographed from as many angles as possible. The varied views of the subjects provide paleoimagers with additional information from which to develop approaches to the imaging tasks at hand. The initial photographs are intended to be a general survey of the subjects. However, if a particular entrance route for the endoscopic procedure is seen, for example, it can be documented using appropriate photographic technique such as macrophotography. Later in the study, a more scientific or forensic approach will be used.

Figure 1.4  (See color insert following page 12.) Photographic documentation of Anga mummies placed on a cliff overlooking their village following mummification. The documentation helps explain the deterioration of the remains seen during paleoimaging research.

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Figure 1.5  Photographic documentation of textiles used on mummy bundles that serves to explain the level of mummification seen through paleoimaging. Grave goods are also documented.

The initial photographs of the subjects are critical to paleoimaging in that they serve to document the condition of the cultural material prior to the initiation of the work. Photographs documenting the condition of the study subjects are also recommended, ensuring that the paleoimaging process caused no damage. Of course, if the paleoimaging work did result in inadvertent damage to the subjects, this, too, should be photographed. The authors have learned that it is beneficial, whenever possible, to time- and date-stamp the photographs. On a paleoimaging project in Italy, the museum director suggested that our team had caused damage to a particular object (Figure 1.7). We were able to vindicate ourselves only because we had a professional photographer who, as part of the team, photographically documented the study subject with a time and date stamp prior to our initiation of any imaging studies. This time-and-date-stamped photograph provided the

Figure 1.6  Photographic documentation of logistic problem resolution. Shown here is a method devised to transport a gasoline generator used to power paleoimaging instrumentation at a remote cave site in the Kabayan Jungle, Luzon, the Philippines.

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Figure 1.7  Photographic documentation of the condition of a study subject prior to paleoimaging procedures. This prestudy photograph proved extremely useful to the team (see text).

necessary evidence showing that the condition of the subject was exactly the same before our research as it was after we had completed our study.

Establishing Workflow Another use of the initial photography is to employ the photographs to establish a workflow scheme for the paleoimaging study. The paleoimager should be with the photographer as these images are obtained. For example, the paleoimager may point out a specific area or location that may work well for the placement of a portable darkroom. The photographs can later be used to explain and communicate the thought process behind the establishment of the workflow for the particular project. The photographs may also serve to provide an assessment of the relationship between and among structural features at the research site. Once the instrumentation is set up, additional workflow documentation is required. Another aspect of workflow as it relates to photography is the role of the photographer during the paleoimaging procedures. A good photographer knows what photographs are required and how to get those photographs without being intrusive. In fact, if it’s a good photographer aware of and familiar with the workflow pattern, you may never know the photographer is there. This “invisibility” is dependent on the skill and experience of the photographer. If the photographer is a permanent member of the paleoimaging team, workflow patterns and relationships may develop naturally. With each team member focused on

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his or her individual unique tasks, enhanced workflow can mean increased efficiency with less loss of time waiting for a particular photograph to be taken.

Documenting Procedures Paleoimaging procedures should be shared with the scientific and academic communities in order to help validate, standardize, and demonstrate reproducible field methodology. A critical part of the field paleoimaging procedures naturally becomes photographic documentation. Photography is necessary to record the technological aspects of the research project. When coupled with images of the study context, photographs of the instruments used in that study are important in order to provide interested researchers with ideas of what types of paleoimaging tools work in what settings. For example, specific endoscopes are selected for specific endoscopic tasks. A small-diameter scope may be used when the opening into the cultural material is very small, while a very long endoscope (Figure 1.8) with supplementary illumination may be used to explore a tomb prior to excavation. The instruments used for each of these applications are unique. Photographs will provide a record of what instrument was matched to which task. Field paleoimaging contexts challenge paleoimagers with many varied situations and physical conditions in which to set up their instruments. Even within the same project, several setups or instrument configurations may be required to attain the desired view or projection. In order to explain exactly how an image was acquired, photographic documentation of the unique setups is required. Figure 1.9 shows a variety of setup situations for field paleoimaging equipment. These photographs will inform interested parties as to the possible equipment configurations when faced with a similar imaging challenge in a

Figure 1.8  Photographic documentation of a 30 ft (9.14 m) portable endoscope used for specific research. The photograph tells future researchers which specific technology was employed for a specific application.

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Figure 1.9  Photographic documentation of varied paleoimaging instrumentation setups. Top left: Endoscopy setup. Top right: Portable radiographic unit and image receptor in field setting. Bottom right: Fixed radiographic unit in a remote research facility. Bottom left: Unique instrument panel.

different setting. As you will read in Chapter 2, using native or local materials is often the best way to solve unique equipment setup problems. Of particular interest to field paleoimaging is the construction of a light-tight space for x-ray film loading and changing. Also, important is the film processing setup (Figure 1.10). Although the construction of darkrooms and film processing space is discussed in greater detail in Chapter 2, it is important to mention here the necessity of photographic documentation of these creations. Each field setting will be different from the last, and the more photographic documentation of these unique setups, the less time will be spent reinventing the process. Another important aspect of photography used in field paleoimaging is that of documenting specific techniques. Any unusual technique, such as a radiograph taken from 40 ft (12.19 m) away from the subject, should be photodocumented. Another example of a special technique would be the imaging of several objects placed on a single image receptor at one time (Figure 1.11). When a radiograph is reviewed for interpretation, the image can be somewhat abstract to those unfamiliar with looking at x-rays, particularly if they do not know or cannot discern the direction or distance from which the x-ray was taken. A photograph taken from the point of view (POV) of the x-ray tube is useful in providing anatomical orientation. The POV photograph coupled with the radiographic image helps lessen the potential of misinterpretation due to lack of proper orientation (Figure  1.12). In the case of endoscopic examination, the entry route into the cultural material must be photographed to orient individuals viewing the endoscopic images to the appropriate anatomical region being studied (Figure 1.13).

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Figure 1.10  Photographic documentation of (clockwise from top left) radiographic unit setup, x-ray film processing in darkroom, film rinsing station, and film drying method.

Any and all field paleoimaging procedures should be photographed in a pre- and postprocedure manner. In particular, any procedures that alter or have the potential to alter the cultural material in any way must be photographed in a pre- and postprocedure fashion. Since these photographs have great implications for future researchers,

Figure 1.11  Photographic documentation of a special radiographic procedure: imaging multiple artifacts on a single film.

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Figure 1.12  Photographic POV documentation serving to orient the viewer in order to assist with orientation and interpretation.

Figure 1.13  Photographic documentation of endoscopic entry routes used to orient the endoscopic image with the object.

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Figure 1.14  Photographic documentation of organic structure following removal from the original context. Shown here is abdominal and coprolite material with scale.

depending on the procedure, the pre- and postprocedure photograph series should be obtained with an orientation to scale. For example, if it is determined that an artificial opening is to be made in an attempt to biopsy material from within remains or artifacts, the procedure narrative must be accompanied with pre- and postprocedure artificial opening photographs. If the procedure involves an actual biopsy or artifact retrieval from within the remains, photographs of the retrieval should be taken. Photographs of the biopsied material or retrieved artifact should be taken once out of the remains or other context in a scientific manner, including orientation to scale (Figure 1.14). As previously stated, field paleoimaging presents researchers with many logistical and technological challenges. Each situation is unique and requires critical thinking and problem solving. Once the procedural problems are resolved, photographs of the technical improvisations may help future researchers who find themselves in similar situations. Often in field paleoimaging projects, the resultant image shows a unique object or structure that appears to be on the surface of the cultural material. Whenever possible, close-up or macrophotography of specific surface targets may be warranted. There are many indications for macrophotography from both an anthropological and archaeological perspective. What we are referring to here is the photographic documentation of those surface features that may explain images obtained through radiography, endoscopy, or advanced imaging modalities (Figure 1.15). For example, x-ray penetration through a set of human remains may have been impeded by sand or dried mud adhering to the part of the remains being imaged. A photographic record of the surface substance helps explain the “opacity” seen on the radiograph. In some cases, an x-ray will reveal a small metallic object often used as offerings or surface adornments in some ancient cultures (Figure 1.16). Due to the overall condition of the remains and the centuries of accumulated surface debris, the metallic object is not readily located visually. The radiograph tells the photographer

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Figure 1.15  (See color insert following page 12.) Macrophotography showing the details of

anatomical anomaly also seen on radiograph. The correlational analysis of the radiograph and the macrophotograph enhance the understanding of the anomaly. Also shown here is the use of “raking,” a lighting technique used to accentuate desired features.

where to search for the surface object and, if found, a macrophotograph can be taken to document the important feature (Figure 1.17). The importance of photography of the many technical aspects and procedures of field paleoimaging also serves to create a record of innovations and ideas that worked, as well as those that did not work. The pre- and postprocedure photographs are critical to the

Figure 1.16  Radiograph showing metallic adornments near the eyes of the mummified remains.

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Figure 1.17  (See color insert following page 12.) Macrophotographic documentation of the metallic structures over the eyes of the mummified remains. The radiograph alerted the photographer to the existence of the unique metallic object, which could then be located and documented.

documentation of the impact of paleoimaging. The surface macro and POV photography assist with the interpretability of the paleoimaging images and enhance the potential for differential diagnoses.

Forensic Photography Forensic photography has long used skilled photographers to document a wide variety of items or remains to be used as evidence in a criminal case. The forensic photographs require a strict adherence to undisturbed contexts and scientific photography. The anthropological and archaeological environments can be considered from the same point of view. In essence, the paleophotographer is collecting evidence from cases that have long gone cold. In addition, many artifacts and anatomical features require the paleophotographer to be skilled in scientific photographic methods. This would include the consideration of perspective in the photograph. In order to accomplish the goal of accurately photographing cultural material, care must be taken to remain scientific and not to objectify the remains or object. As previously discussed, macrophotography and photography of biopsied material or artifacts retrieved from within remains or bundles need to be photographed with orientation to scale. Many times, the biopsied material or artifacts are radiographed outside of the remains. The photograph with orientation to scale increases the interpretability of these images. Many archaeological items such as grave goods (Figure 1.18) or unique anthropological variations such as cranial modification need to be photographed with orientation to scale. These photographs can then be compared to the radiographs or endoscopic images of the same item or subject. If the paleoimaging project involves a museum, photographs taken that are associated with other paleoimaging data may also serve as a formal record of museum holdings and may be recorded in the museum catalog.

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Figure 1.18  Photographic documentation of grave goods with scale. Shown here is a nonperpendicular photograph demonstrating an error in photographic perspective.

Special Photographic Techniques During paleoimaging projects, unique features may be present on the cultural material. The importance of macrophotography has already been discussed. At times, remains are adorned with culturally significant tattoos. Standard photography may very well document the overall shape and configuration of the tattoo. Special photographic filtering techniques, such as infrared, can bring out the features of these tattoos, increasing the interpretability of the image. A variety of filters are available to the trained photographer, and their description and applications are beyond the scope of this chapter. Lighting techniques are also important for the paleophotographer. Portable adjustable lighting systems are used by paleophotographers to obtain macro- and nonmacrophotographs that are free from glare or flashback from strobes. Another lighting technique employed by the paleophotographer is to bring the light in from an angle, accentuating the subtle depth variations of the subject not seen on a photograph produced from straight on lighting. This lighting procedure is called raking. Raking can “bring out” important surface features on the cultural material, enhancing the data collected and increasing the interpretability (see Figure 1.15). In situations where no external light can be used, such as within a portable darkroom, the paleophotographer must be skilled in low-light or no-light photography.

Summary The relationship between photography and the documentation needs of paleoimaging research is clear. During a paleoimaging project, the photographer must be aware of what needs to be photographed and when. This knowledge comes only from fieldwork experience as a member of the paleoimaging team. We have used forensic photographers, as well as professional photographers experienced in archaeological and anthropological settings, as paleoimaging team members with excellent results. New photographers or student

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assistants may also function as the team photographer, only if the team anthropologist, paleoimagers, or a seasoned fieldwork photographer properly mentors them. A key point of this chapter is that there must be a team member who is responsible for the photographic needs of the team. Each team member has his or her own area of expertise. If a paleoradiographer or endoscopist also tries to be the team photographer, important information will potentially be missed. An individual dedicated to and skilled in photography will make critical contributions to the outcome of the paleoimaging research study.

References Aufderheihe, A. C. 2003. The Scientiἀc Study of Mummies. Cambridge: Cambridge University Press. Collier, J. and M. Collier. 1986. Visual Anthropology: Photography as a Research Method (revised and expanded edition). Albuquerque, New Mexico: University of New Mexico Press. Edwards, E. (ed.) 1992. Anthropology and Photography, 1860–1920. London: Royal Anthropological Institute.

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Gerald Conlogue and Ronald Beckett Contents Introduction Evolution of Conventional Radiography in Anthropology and Archaeology Background: Mummy Mania Begins Early Radiographic Applications: Exploring Possibilities Modern Radiographic Applications: Refinement and Technological Progress Conventional Radiography: The Basics Exposure Variables X-Ray Penetration Focal Spot Source-to-Image Distance Image Distortion Beam Collimation Image Receptor: Film and Screens Darkroom: Film Processing Field Radiography Applications: Considerations and Challenges General Considerations Field Imaging: Specific Considerations The Radiographic Unit Utilities X-Ray Tube Support System Image Receptors Darkrooms Film Drying and Viewing Instant Film Positioning Devices to Maintain the Position of the Remains Devices for Holding the Image Receptor Unique Technical Challenges Summary of Unique Technical Challenges Technical Advantages and Disadvantages of Conventional Radiography Technical Advantages Technical Disadvantages Complementary Data Acquisition Anthropological Applications: Laboratory and Field Objectives for Conventional Radiography Fundamental Objectives 19

20 21 21 21 22 23 23 23 27 28 28 29 29 33 34 34 35 35 36 37 39 42 49 50 56 62 64 65 88 89 89 90 90 91 91

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Assess Condition of the Remains or Artifact Age at the Time of Death Determination of Sex in Absence of Direct Observation Dentition Refinement Objectives Detection of Pathologies (Paleopathology) Target Identification for Biopsy and Retrieval Cultural Practices Temporal Context Mechanism of Death Summary and Future Applications References

91 91 92 94 95 95 99 108 118 119 119 119

Introduction Undeniably, one of the greatest medical advances during the 20th century was the development of radiography. The lives of countless individuals have been saved because physicians were able to “look” inside the patient with images produced by x-rays. Similarly, radiography has been an invaluable tool in archaeology and anthropology. The discipline of radiography has greatly expanded since Wilhelm Röntgen’s first public demonstration during the January 23, 1896 address to the Würzburg Physical Medical Society (Eisenberg 1992a). Today there are a number of modalities or methods under the broad area of radiography. Conventional, standard, or plain radiography are the commonly employed terms to identify the imaging modality that utilizes a basic x-ray source and film as the recording medium. It has been suggested that the optimal location for a conventional radiographic examination of archaeological and anthropological material is a hospital or research imaging facility (Chhem and Brothwell 2008a). However, since the modality has the advantage of being highly mobile, it has been easily applied in remote areas. Such portability makes conventional radiography a powerful field data acquisition method for anthropological and archaeological research. Based on experience, the authors have adopted the philosophy that skeletal and mummified remains should be imaged within or as close to the recovery site or storage facility as possible. Using field radiography as a primary approach, there is minimal disruption of the taphonomic context. Transporting mummified remains can alter the location of foreign bodies and/or artifacts within the mummy, complicating the interpretability and, therefore, the significance of those materials and their spatial associations. Transportation from remote locations to imaging facilities carries the added risk of physical damage to the often fragile remains. Additionally, field radiography has the potential to collect radiographic data from large populations of mummies, making it possible to conduct statistical analyses. Although population studies can be conducted at imaging facilities, it is logistically more challenging. Transportation of 200 mummies to a facility has not been reported in the literature. Radiographic examination in the field can also be used to triage a large group of remains in order to select those that would yield more data from advanced imaging modalities, such as computed tomography, and thus justify transportation to an imaging facility. Finally, due to the remoteness of many research locations, field radiography may be the only way to gather critical data and conduct imaging examinations.

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Although a more complete review can be found elsewhere (Böni et al. 2004; Chhem and Brothwell 2008b), this chapter will describe some of the contributions made by conventional radiography to anthropological and archaeological research from a historical perspective. The focus will be more on the discussion of the basics, equipment development, and the many variables related to the instrumentation challenges experienced during field applications. Further, this chapter will describe the manipulation of technical factors and the use of ancillary equipment that will increase the likelihood of acquiring diagnostically acceptable images. The chapter will also present the research objectives of conventional radiography in these field environments.

Evolution of Conventional Radiography in Anthropology and Archaeology Background: Mummy Mania Begins Mummy mania found its way into Western European culture in the mid- to late 1800s. Mummies or mummy parts from Egypt were purchased from mummy vendors on the streets of Cairo by European travelers and scientists. Ancient artifacts were brought back to America or Europe and became family heirlooms. These heirlooms eventually found their way into museums. However, a major problem associated with this type of mummy commerce and collection became apparent. A traveler or scientist could purchase a mummy with nice wrappings and place them in an unassociated coffin with well-preserved hieroglyphs. The mixing and matching that occurred at the time of purchase caused many curators and scientists to believe that the inscription on the coffin lid, which referred to the intended occupant, may in fact not be related in any way to the actual mummified remains inside. The problem of mismatched remains, artifacts, and coffins continues to challenge curators and historians today. Mummy mania was so prevalent that it was reported that mummies were used as medicine, paint pigment, fuel for steam locomotives, and for social events such as mummy unwrappings (Aufderheide 2003a). These unwrappings drew many observers. What was of great interest to the audience was not the human remains inside but rather the artifacts associated with the mummy, such as amulets and jewelry. Within the same time frame, mummies were being discovered in parts of the world other than Egypt. In the late 1800s, Max Uhle, considered the father of South American archaeology, was discovering mummies from a completely different part of the world (Aufderheide 2003b). Uhle’s work brought the world’s attention to places such as Bolivia and Peru, which were rich in mummified remains and artifacts. Mummies were everywhere, and radiography had played an important role in the scientific study of the mummified remains and their associated artifacts since the discovery of the x-ray. To place radiographic research and analysis in anthropology and archaeology in perspective, an understanding of the historical contributions made by researchers using radiography to study mummified remains and artifacts is warranted. Early Radiographic Applications: Exploring Possibilities On November 8, 1885, Wilhelm Conrad Röntgen accidentally discovered x-rays while working on a Crooke’s tube project. The first x-ray was taken of Bertha Röntgen’s hand, clearly showing her skeletal structures and her wedding band. The exposure time required

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was 15 min. Soon after Röntgen’s discovery, German physicist Carl George Walter Koenig published a paper in March of 1896 titled “14 Photographs with X-rays Taken by the Physical Society of Frankfurt am Main” in which he presented the first x-rays taken of mummified remains, including an Egyptian cat mummy and the knees of an Egyptian child mummy. That same year, a mummified bird was radiographed by Thurstan Holland. Another early use of radiography related to the study of mummified remains, reported in 1896 and in 1897 by Alexander Dedekind, was to use x-rays to distinguish between real and fake mummies. Also in 1897, Albert Londe radiographed a fake Japanese mummy and an authentic forearm and hand of an Egyptian mummy. Londe’s work demonstrated the value of seeing what is inside mummy wrappings without having to unwrap the remains. In May of 1897, Charles Lester Leonard and Stewart Culin radiographed a Peruvian mummy. Their work further demonstrated the ability to “see” within without having to unwrap. Culin reported that the mummy being studied was so fragile that unwrapping it would have destroyed it, supporting the use of radiographic examination not only to see what was inside but also to assess its state of conservation. Karl Gorjanovic-Kramberger used radiographic techniques in 1901 to examine hominid fossil teeth. Gorjanovic-Kramberger was attempting to develop a way to overcome the magnification found on radiographic images and established radiography as a nondestructive tool in phylogenetic analysis (Boni et al. 2004). Soon, the use of radiographic data was expanded to include not simply seeing inside the wrappings or to disclose frauds but also to collect anthropological and pathological data. In 1904, Gardiner radiographed mummies from the collection at the British Museum and reported the first use of radiographs to determine the age of a mummy’s bone and, therefore, the age at the time of death. Heinrich Ernst Albers-Schoenberg published a paper in 1905 describing an extensive radiographic examination of mummies and is credited with assessing soft tissues and dental pathology in mummies. This is one of the first reports to describe pathological conditions in mummified remains. Additional studies conducted in the early part of the 20th century further explored the varied uses of radiographs in anthropological settings. Each time a new imaging modality became available, it was applied to mummy studies shortly after its inception. Modern Radiographic Applications: Refinement and Technological Progress In 1973, James Harris and Kent Weeks published X-Raying the Pharaohs. In their book, the authors describe the expanded use of radiography in mummy research to examine such characteristics as diseases present, medical and dental problems, age at the time of death, cause of death, process of mummification, artifact analysis, and the impact of grave robbers and movement on the mummified remains. The works reported by Harris and Weeks were conducted at the Cairo Museum in Egypt and demonstrate the significance of conducting radiographic studies in the field. The damage done to mummified remains by transport and grave robbers makes a strong case for conducting radiographic studies in the field as near the original context as possible. Computed tomography and magnetic resonance imaging bring wonderful imaging potentials to the arenas of anthropological and archaeological research. Although these advanced imaging modalities offer remarkable data collection capabilities, the remains or artifacts under analysis need to be moved to the imaging facility, risking damage to the remains and possibly an alteration of biological or artifact spatial orientation within those remains. Although there are reports of advanced imaging being done in the field, these

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studies are expensive and logistically limiting. Conventional radiography technology can be very portable, allowing researchers to collect data at the original context, within a cave, a tomb, in a jungle or desert, or at remote research facilities (Conlogue et al. 2004). It is from these field applications that the most accurate radiographic data, free from “travel damage,” can be collected and, therefore, the most meaning made of those data. The remainder of this chapter will describe some of the basic principles of radiographic imaging and the application of conventional radiography in field settings. It is beyond the scope of this book to provide a comprehensive presentation of the physical basis of the principles of x-ray production. Readers interested in a more detailed discussion are directed elsewhere (Bushberg et al. 2002; Bushong 2008a). Because field imaging using conventional radiography is “unconventional,” many challenges can, and will, arise. These challenges are described, and solutions are discussed.

Conventional Radiography: The Basics Conventional radiography is still the method most frequently used to initially examine artifacts, victims for forensic examination, and mummified and skeletal remains. Since Röntgen’s 1895 discovery, many modifications have changed the design of x-ray equipment. However, the basic principles of x-ray production have remained unchanged. That is, within the x-ray tube, electrons are accelerated from the filament within the negative electrode, or cathode, to the target within the positive electrode, or anode. The interaction between the high-speed electrons and the target material produces x-rays. Exposure Variables X-Ray Penetration There are several variables that are manipulated in the production of x-rays. The penetrating ability of the x-ray beam is controlled by the acceleration of the electrons across the tube. An increase in the electron speed will result in shorter-wavelength photons that are more penetrating. Conversely, a stream of slower-moving electrons will produce an x-ray beam consisting of longer-wavelength photons that are less penetrating. The factor on the control panel that adjusts the speed of the electrons is the kilovoltage (kV). When the numerical value is selected, it indicates the maximum kV, or kV peak (kVp), that will be applied to the cathode. This penetrability of the generated x-ray is considered the beam quality. For each density and thickness of material, there is an optimal kVp setting. For example, on a living patient, the optimal setting would be 55 kVp for a hand and 75 kVp for a lateral skull. Pathology that alters the density of tissue would necessitate compensation in the selection of kVp. For instance, a patient with osteoporosis, a condition that decreases bone density, might require a 5 to 10 kVp reduction to produce an image with acceptable penetration. For mummified remains, 55 kVp has proved to be most suitable for adequate penetration. When viewing a processed radiograph to determine if there is adequate penetration, looking “inside” the bone is considered the best area for an assessment of penetration. It should be possible to see “through” the bone and be able to discern structures such as trabeculae (Figure 2.1A). If it is not possible to see through the bone, the film is considered underpenetrated (Figure 2.1B). If it is possible to see through the bone but the cortex of the bone appeared gray instead of white, the film is considered overpenetrated

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Figure 2.1A  Lateral skull radiograph of the mummy known as George/Fred, taken at 55 kVp and 10 mAs. To assess the penetration, look at the teeth. Since it is possible to identify all the anatomical features, such as pulp canal, enamel, and dentine, the image is properly penetrated. To assess the density, look at the areas outside of the skull either in front of the teeth or behind the neck.

Figure 2.1B  The same projection, but taken at 40 kVp at 20 mAs. Because the mAs value was doubled from the previous exposure, it compensated for the decrease in the kVp, and the resulting films have the same density. However, since the anatomical features of the teeth are not discernable, the penetration at 40 kVp was insufficient and the image can be considered underpenetrated.

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Figure 2.1C  Another lateral projection, this time taken at 80 kVp at 5 mAs. Once again, the mAs value was adjusted to produce a density similar to the two previous images. The high kVp setting resulted in an image in which all the anatomical features appear as shades of gray and are not easily distinguishable. The image can be considered as overpenetrated.

(Figure 2.1C). Between the range of 55–80 kVp, the minimum change in kV to produce a noticeable difference in penetration is approximately 5 kV. Because the kV setting controls the penetrating ability of the x-ray beam, it also controls the visible contrast, the difference between black and white, on the image. Therefore, lower kVp settings are less penetrating and produce images that possess higher contrast: more “black and white” with fewer shades of grays. Conversely, higher kVp settings will generate more penetrating x-rays, resulting in lower-contrast images: more shades of gray and fewer areas of “white.” In addition to the quality (kVp) of the beam, there are variables that influence the quantity of x-rays produced. Manipulation of the quantity of x-rays is accomplished by manipulating two complementary factors, milliamperage and time. Milliamperage (mA) determines the quantity of electrons that will be available at the filament within the cathode. Time, usually in seconds (s), determines the duration of the exposure. Together, these factors combine to produce the milliamperage-seconds (mAs) and influence the overall “blackness,” or density, on the processed film. The region on the processed film to assess adequate density is the area around the part or object of interest. That area should be sufficiently “black” so that when the film is held up to the light, you can’t see your fingers placed about 10 in. (25 cm) behind the film. A film that lacks sufficient density, or “blackness,” is termed underexposed (Figure 2.2A). Conversely, if the film is too dense, it will obscure the part of interest and be termed overexposed (Figure 2.2B). In order to see a visible difference in density on a processed film, the mAs value either must be increased or decreased by a minimum of 50%.

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Figure 2.2A  A lateral projection of the skull taken at 55 kVp at 5 mAs. From the previous

image, Figure 2.1A, it was determined that the kVp selected provided sufficient penetration. However, because the soft tissue structure of the nose was clearly demonstrated and the area in front of the nose was “gray” and not “black,” the image must be considered underexposed.

Figure 2.2B  This lateral projection was taken at 55 kVp at 20 mAs. One again, the satisfactory kVp was selected; however, the mAs value is so high that the entire image is dark and should be considered overexposed.

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Shoulder

Density

Straight line

Toe

Exposure

Figure 2.3  The characteristic curve: graphical representation of the relationship between the intensity of the radiation exposure and the resulting density on the processed film.

The study of the relationship between the intensity of the radiation exposure and the resulting density, or blackness, on the film is known as sensitometry (Bushong 2008b). Although a thorough understanding of this complex topic is beyond the scope of this text, it will serve as a reference point later in the discussion of digital radiography. The graphical representation of sensitometry is known as a characteristic curve, or a Hurter and Driffield (H & D) curve (Figure 2.3). The graph is divided into three sections: the toe, straight line, and shoulder. Film exposures in the region of the toe would be considered grossly underexposed, whereas in the shoulder the effect would be extremely overexposed. The acceptable exposure would be in a narrow portion of the straight line region where smaller changes in mAs result in more noticeable differences in film density. The slope, or gradient, of the straight line section determines the film’s maximum contrast or latitude. A film with a steep slope would have inherently higher contrast, and as the slope decreases, there would be more latitude, lower contrast, and more shades of gray on the processed film. Focal Spot The area of the anode or target that is bombarded by the electron stream is known as the focal spot. The dimension of this area becomes significant when taking into consideration the interactions between the principal exposure factors, kVp and mAs. Only approximately 1% of the energy of the electron stream is converted to x-ray, and the remainder is lost as heat. The heat generated at the focal spot in the anode is directly related to three factors: the quantity (mA) of electrons available at the filament, the duration of the exposures, and speed of the electrons (kVp) applied to the filament. A fourth factor, the current waveform, is determined by the type of voltage fluctuation and may be identified simply as single phase, three phase, or high frequency. Single-phase current represents the greatest voltage fluctuation; it is the least efficient means of x-ray production and affects heat production the least, whereas high-frequency generation results in the least voltage variation and is the most efficient x-ray production during an exposure, but contributes significantly to anode heating.

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Since overheating of the anode reduces x-ray tube life, tremendous engineering efforts over the past century have been invested in designs to dissipate heat. The simplest and most basic design, the stationary anode supplied with single-phase current, was commonly found in dental and some portable units with lower kVp and mA outputs. These units generally had larger focal spots (1.0 mm/2.0 mm) and were the least expensive, but required longer exposure times to deliver the necessary amount of radiation. X-ray procedures that require very short exposure times necessitated equipment with high-frequency generators capable of higher kVp and mA settings and a smaller focal spot (0.5 mm/1.0 mm) embedded in a rotating anode to dissipate the tremendous heat produced. Most x-ray equipment found in hospital imaging centers, including modern portable units, is powered by high-frequency generators. In order to minimize damaging the x-ray tube, Manufacturers provide charts that indicates maximum kVp and mAs settings related to anode cooling times. The size of the focal spot ultimately determines the size of the object that can be visualized on the processed image. The smaller the focal spot, the sharper the image. Simply stated, a structure smaller than the focal spot size will not be clearly demonstrated. In medical imaging, mammography units have fractional or microfocal spots, less than 1 mm, typically 0.1 to 0.3 mm, to enable visualization of microcalcifications in the breast tissue. However, the smaller the focal spot size, the faster the anode will heat up. Therefore, focal spot size should be taken into consideration once the objectives of the study have been determined. Source-to-Image Distance The distance between the x-ray source and the image receptor also affects the exposure settings. Referred to technically by several terms such as the source-to-image receptor distance (SID), target-to-ἀlm distance (TFD), and focal ἀlm distance (FFD), this distance is based on the physical principle that x-ray photons diverge from the source of production. Because x-ray and visible light are both forms of electromagnetic (EM) radiation, the dispersal characteristics of both are identical and obey the inverse square law. If the SID is doubled, the intensity of the radiation would be reduced by 1/4. To compensate for the reduction of radiation, the quantity, or mAs, would have to be increased by a factor of 4. Therefore, the compensation procedure is known as the direct square law. For example, a satisfactory image is obtained using 10 mAs at a 100 cm SID. If the same object was radiographed at an SID of 200 cm, the quantity of radiation must be increased to 40 mAs to produce an image of satisfactory density. Image Distortion The appearance of the object on the image is affected by the SID and focal spot size (fss). Radiographs were originally known as shadowgrams or shadowgraphs because they resembled shadows cast by light. As previously mentioned, the dispersal rate of both forms of EM are identical and can therefore be demonstrated using visible light. To demonstrate this concept, position a light 40 in. (100 cm) from a wall. The wall represents the image receptor or the film. Place an object, for example your hand, 4 in. (10 cm) from the wall in the path of the light, and the shadow of your hand will be cast on the wall. Around the margin of the shadow is a “fuzzy” region known as the penumbra. As your hand moves closer to the wall, the shadow and the penumbra will reduce in size or be less magnified. If you move your hand further from the wall, the shadow and penumbra will get larger or more magnified. Therefore, in order to minimize magnification and penumbra, the object

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should be closest to the film, or more precisely, the object-to-image receptor distance (OID) should be as small as possible. However, unless the object is flat, the parts farther away from the film will be magnified more than those closest to the film. This unequal magnification is termed distortion. Parts of the object that are not in the same plane as the film will appear distorted on the processed image. Magnification and distortion are two related disadvantages of conventional radiography. Consequently, to minimize magnification and distortion, always place the part of interest closest and in the same plane as the film. If there are several parts of interest, additional exposures should be taken to ensure that each region or area of interest is closest and parallel to the film. Since it is extremely difficult to get all body parts, foreign bodies, and/or artifacts parallel to the film, it is fundamentally impossible to totally eliminate distortion. If the target structure of interest is successfully positioned parallel to the film, the actual size of the object can only be determined if the distance between the object and the film is known. Therefore, it is extremely difficult to determine the actual size of an object from a radiograph. Beam Collimation As previously indicated, x-rays diverge from the source at the same angle as visible light. A visible light source superimposed over the path of the x-ray beam and projected onto the subject will indicate the area of the subject that will be irradiated. When adjustable lead shutters are added to the visible light projection device, termed a collimator, it is possible to linearly shape the area that will be irradiated. There are three principal benefits to collimation. First, it greatly reduces scatter radiation, which degrades the image and reduces contrast. Second, it decreases radiation exposure to the patient and operator. Third, it allows the x-ray beam to be precisely centered and limits the area irradiated to only the area or part of interest.

Image Receptor: Film and Screens In 1895, the image receptors for photography included glass plates, flexible films, and papers coated with a light-sensitive emulsion. However, in Röntgen’s initial communication to the Würzburg Physical Medical Society, he stressed the importance of using photographic plates (Gagliardi 1996a). The plates were manufactured in “standardized” sizes, including 14 × 17, 11 × 14, 10 × 12, 8 × 10, and 5 × 7 in. Prior to being exposed, the lightsensitive plate was placed into a “light-tight” envelope. A 14 × 17 in. glass plate weighed approximately 2 lb (4.4 kg), was fragile and, because of its thickness, difficult to handle for direct viewing. Therefore, prior to interpretation, direct contact prints of the images were made on sensitized paper (Gagliardi 1996b). Radiography lexicon still contains an allusion to this original recording media: an anterior-posterior, supine projection of an abdomen is commonly referred to as a flat plate of the abdomen. A wrist x-ray on a glass plate in the early 1900s required a 30-min exposure. The long exposure was because less than 1% of the x-rays reaching the image receptor contributed to the formation of an image (Bushong 2008c). In February 1896, Michael Pupin, a Columbia University physicist, received a fluorescent screen from Thomas Edison. Since the screen, developed by Edison, fluoresced or converted x-ray to visible light, Pupin theorized he could reduce the exposure time by combining it with a photographic plate. He succeeded

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in producing the first intensifying screen-film image of a hand demonstrating the location of a shotgun pellet with an exposure of a few seconds (Eisenberg 1992b). By 1913 the high cost and other problems previously stated regarding the plates led to a search for a replacement film base. Because the finest glass specifically manufactured for x-ray exposure was produced in Belgium, World War I forced many nations, including the United States, to search for another substrate for the photographic emulsion. Cellulose nitrate was one of the first to be marketed with an emulsion coated on a single side. Because cellulose nitrate was flammable, it was soon replaced with cellulose acetate and today with polyester. Glass plates were still available at least until the mid-1980s for special applications (see Chapter 7, Figure 7.26). The photosensitive crystals in the emulsion were considered “ultra-fine grained” and the resulting images could be magnified many times. By eliminating the glass base, the thinner films had an emulsion that was more sensitive to x-rays and had a more conducive fit into a holder or cassette equipped with an intensifying screen. In 1918, Kodak introduced an x-ray film with an emulsion on both sides that could be placed into a cassette equipped with two screens. This new combination drastically reduced the exposure time and the radiation dose to the patient. In order to acquire a high-resolution image, nonscreen film was still used for some medical procedures, such as mammography, through the 1960s but single-emulsion nonscreen film was primarily relegated to industrial applications. Nonscreen film holders, often referred to as a cardboard holder, were commonly available through the early 1970s for mammography. However, by that time, a single high-resolution screen, single-emulsion film combination was developed for mammography. Although the single-emulsion film requires more radiation to achieve an acceptable image, it has one advantage over double-emulsion film: a less blurry and sharper image. Double-emulsion film, even though the film base is very thin at 150–300 µm (Bushong 2004a), provides two images separated by a very small distance. The result is a phenomenon known as parallax. When viewing objects a millimeter or less in size on doubleemulsion film, parallax results in apparent blurring of the object’s margins. For situations in which magnification is necessary, such as mammography, a single-emulsion film and single high-resolution screen is employed. Another benefit of a nonscreen approach is that the resulting image has increased latitude or more shades of gray. If the x-ray unit can produce the high mAs values required for nonscreen imaging, it will provide the best images (Figures 2.4A and 2.4B). In medical radiography, there has always been a trade-off between producing a diagnostic image and reducing the radiation exposure to the patient. To achieve this goal, films were developed with emulsions that were more sensitive to the light emitted by the intensifying screen. Similar to photography, one method to produce “faster” films was to increase the size of the light-sensitive crystals embedded in the emulsion. With an increase in crystal size, the exposure to the patient was decreased, but there was a corresponding decrease in detail or resolution on the processed film. A similar process occurred simultaneously in the development of intensifying screens. High-energy x-rays photons interact with the crystalline material in the fluorescent layer of the screen and are converted to many lower-energy photons of visible light. The larger the crystal embedded in the fluorescent layer, the more light photons generated from a single photon of x-ray. A high-speed screen would be very efficient at converting x-ray to light, but at the cost of a loss of detail. However, another consequence of using intensifying screens is an increase in contrast over nonscreen images. Without screens, the image is produced

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Figure 2.4A  An anterior-posterior, or AP, projection of the abdomen of an Egyptian mummy from the library at Cazenovia, New York, taken with a screen cassette. Note the high-contrast appearance, black and white with few shades of gray, of the image. An organ packet can be easily seen in the abdomen (arrow). Below the packet, the entire area appears as a “black” void.

solely by the differential absorption of x-rays. The visible light emitted from the screen eliminates some of the subtle differences in density that produce the shades of gray on the processed film. The result is fewer shades of gray and more black and white. Screens are rated according to their ability to convert x-rays to visible light. A slow speed screen may be assigned a value of 100. For the sake of simplicity, let’s say it will convert one photon of x-ray to 100 photons of light. This means that the original exposure variables (mAs) without screens can be reduced to 1/100 of the mAs with the intensifying screens. A par speed screen would be rated at approximately 200, a high-speed screen at 400, and an ultrahigh-speed screen at 1200. Shorter exposure times have two advantages: they reduce the radiation dose to the patient and eliminate involuntary movement, which would blur the image. A high-speed film/screen system would be an excellent choice for a chest radiograph when it is important to reduce the exposure time to minimize the effect of heart motion. However, the high-speed system would render very little trabecular detail within the long bones. Orthopedic radiography, on the other hand, would use the slower-speed screens to produce bone images with more detail. Therefore, for optimal results, film and screens of similar speeds would be matched for specific imaging objectives. If film and screens are not matched, the exposure (mAs) required may need to be adjusted and the resulting shades of gray, or latitude, available on the processed image may be compromised. There are also specialty cassettes for specific applications. Standard x-ray film comes in a 14 × 36 in. (35.5 × 91.4 cm) size and is typically used in orthopedic or chiropractic medicine to image an entire spine. This film size requires a special cassette. These specialized

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.4B  The same region radiographed with a nonscreen film holder. Since an intensifying screen was not used, the film had lower contrast with many shades of gray visible. As in the previous image, the abdominal packet was seen; however, soft tissue structures were noted where there was only a “black” void with the screen image.

screens are also available with varied degrees of intensification, with one end of the cassette being faster than the other. Xeroradiography, or dry radiography, was a type of radiographic technique in which the image of the body was not recorded on film but on paper, eliminating the need for wet film developers (Selman 1985). In this technique, a plate of selenium, resting on a thin layer of aluminum oxide, was charged uniformly by passing it in front of a screen-controlled corona device termed a scorotron. As x-ray photons interacted with this amorphous coat of selenium, charges diffused out, in proportion to energy content of the x-ray. This process was a result of photoconduction. The resulting imprint, in the form of charge distribution on the plate, attracted toner particles, which were then transferred to reusable paper plates. By the late 1970s, xeroradiography became an alternative to using film for mammography. There were a number of advantages over the film, including lower patient dose than with nonscreen film mammography, a dry chemical process, margins of varying density materials were enhanced, and wider latitude that demonstrated more materials with similar densities (Gagliardi 1996c). In addition, because it was printed on paper, a view box was not needed to view the image. In 1977, a French team used xeroradiography to obtain a lateral image of Ramses II’s skull. The image revealed that the embalmer packed the pharaoh’s nasal cavity with peppercorns and employed a small bone to support the tip of the nose (Lang and Middleton 1997). By 1990, xeromammography was replaced by a

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single-screen film system that provided better images at even lower patient doses (Bushong 2004b). Subsequently, Xerox stopped making the toner required for the processes, and xeroradiography became another footnote in imaging history. In the past decade or so, shortening the length of time it takes to complete the patient’s examination has also become a consideration. The more patients examined in an hour, the higher the profits to the imaging center. This concept, termed throughput, has been a factor in the development of new hardware and software, and will be discussed in more detail in Chapter 3. Since the emulsion slowly deteriorates over time, medical imaging film has an expiration date, and medical facilities cannot use outdated film on patients. This expired film can be a tremendous resource for field forensic or anthropological research projects. Outdated film can be obtained either from medical facilities or vendors; however, there will likely be a mismatch between the film and light frequency emitted by the screens. Several test exposures will be necessary to formulate a technique chart for the optimal mAs settings.

Darkroom: Film Processing Since radiographic film is sensitive to light, a light-tight enclosure is necessary to load cassettes and process the film. The first requirement has always been less complex than the latter. A formal darkroom is described as a room that is light tight, has the appropriate chemistry available for film processing, and has a source of fresh water. Until about the early 1960s, most exposed x-rays were processed manually. Tanks were required for developer, water, and fixer. In addition, copious quantities of running water were necessary to wash the fixer from the processed film prior to drying. Not to get too technical, the function of the developer is to serve as a reducing agent, donating electrons to the exposed silver ions in the film emulsion and thus converting them to black, metallic silver. Each sheet of x-ray film consumes a certain amount of donated electrons and eventually exhausts the developer. To compensate for exhausted developer, a concentrated developer termed replenisher is periodically added to the tank. In addition, because the developer is a reducing agent, it is very susceptible to oxidation and can be inactivated if exposed to air for long periods of time. The action of the developer is temperature dependent. At 68°F (20°C), development, with agitation of the exposed film, should be 5 min. Combined with the time for fixing, washing, and drying, the entire process could take 30 min before a processed, dried image could be examined. The term wet reading found its way into the lexicon to indicate a film that was viewed by the radiologist prior to having completed the drying process. Under normal circumstances this long period was acceptable; however, in emergency trauma or operating room cases it was unacceptable. In 1951, a Polaroid system was introduced to eliminate the need to wet process film (Robbins and Land 1951). The system that provided an “instant” image within 90 s became obsolete with the advent of automated or automatic processors and ended Polaroid’s intervention in the medical imaging market. By today’s standards, the early processors were massive, but a dry image was available in about 5 min. Today, processors are manufactured for low-volume operations that can fit onto a darkroom countertop and take about 2 min to produce a dry film. To achieve the shortened developing time, the processor runs at about 95°F. Since film development is

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a temperature-dependent process, fluctuations even as little as 5° higher or lower may result in an over- or underdeveloped image. In addition to the temperature, automatic processors also maintain the concentration of the developer by introducing a specific volume of replenisher each time a film is introduced into the unit. The specific design of automatic processors is partially based on the expected volume of films that will be processed in a day. Although automatic processing is available in many locations, aspects of image production such as daily volume, replenishment, and temperature regulation are major reasons for production of an unacceptable image. Clearly, the challenge of regulating these variables is amplified in the field imaging setting.

Field Radiography Applications: Considerations and Challenges General Considerations Field radiography may be defined as a radiographic examination outside of an established imaging center. Contextual examples for field radiography include remote research facilities, tombs, caves, and museums. Considerations regarding field radiography instrumentation and technique are determined by two primary factors: the proposed location of the study and the specific research goals. Each of these factors in turn produces a wide variety of additional considerations to be addressed while planning the field-imaging project. The first step in any research project is to define the objectives, and this is no different for a field-imaging study. If the objective of the project is to complete an imaging triage study of a group of mummies in a remote location outside the United States, the preparation will certainly be different than if the remains are housed in a nearby museum. When determining which instrumentation to employ and what type and quantity of image receptors to use, the paleoimager must consider such variables as the following: 1. How many mummies and/or skeletons are associated with the project? 2. What will be the minimum projections required? 3. What is the predominant cultural practice with regard to mummification position, extended or flexed? 4. What is the nature of the travel required by the project? 5. How can the necessary equipment and supplies be kept to a manageable weight yet include everything that might be required? 6. What problems may be encountered when trying to transport x-ray film, since film packed in checked baggage will be subject to security x-ray inspection? 7. What are the issues surrounding the customs requirements for entering foreign countries and returning your equipment back into your country of origin? 8. Is a list describing the equipment and their serial numbers necessary? 9. Is a list of equipment all that will be needed or is additional official documentation required? It is apparent that many considerations need to be taken into account in field radiography projects. These and other factors are addressed in the following sections.

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Field Imaging: Specific Considerations The Radiographic Unit Although selecting an x-ray unit may be based on what you can get as dictated by budget or donation, it cannot be stressed enough that the equipment needs to be operated by a trained radiographer with paleoimaging experience. After providing some training, on occasion the authors left equipment with researchers in the field, only to find that they did not anticipate the impact of their application on the unit itself. In one instance, while attempting a long exposure, the unit overheated and the filament broke, rendering the unit inoperable. Without proper knowledge of exposure settings, positioning, and safe unit operation, the results can be disastrous. There are several ways in which the tube can be cooled, but the key is in knowing how to achieve the imaging objectives without damaging the equipment. A variety of challenges to conducting field radiographic work arise when planning and executing such expeditions. The instrumentation not only has to be compact and light enough to be transported, but also flexible enough to be able to adapt to any number of possible application situations. Dependability of the selected unit is critical. Many of the field challenges described in this chapter are applicable to conventional radiography applications in imaging centers as well, particularly in the forensic setting. Although the authors do not object to radiographic studies of mummified remains being conducted at imaging centers, we feel it is imperative that initial radiographs be conducted on site to determine if the mummy can be moved and if the preliminary data suggest that transportation and its inherent risks are warranted. A new high-frequency-generated portable x-ray unit would certainly be the simplest approach to an x-ray source. At a cost of approximately $12,000, a MinXray HF 100/30 veterinary unit comes equipped with a collimator and laser-centering light. In addition, it is packed into a nearly indestructible transport case, and together they weigh less than 50 lb (23 kg). However, older operational x-ray units abound. Most, such as dental and mobile x-ray units, are low output, generally not greater than 15 mA and 80 kVp. Since mummified and skeletal remains only require 55 kVp and, due to the lack of motion, long exposure times are not a problem, these units certainly meet the needs of anthropological and archaeological research. Older dental, medical, and veterinary portable units can usually be disassembled into two separate components, a control unit and an x-ray tube. These nonmounted components can be easily packed for transport and then reconfigured on-site to meet the imaging needs of the particular project. Often, project directors in locations where there are large stores of mummified remains desire a permanently mounted radiographic unit at the research site. In some of these situations, a mounted x-ray tube is put in place. Unfortunately, a permanently mounted x-ray tube loses the flexibility of application needed. A fixed x-ray tube requires that the subject be brought to the unit and, frequently, the ability to angle the tube is sacrificed. Tube angulation is often necessary to place a body part parallel to the film. The preferred approach is to use a nonpermanently mounted system. This method allows the tube to be placed and directed as the case dictates. The nonmounted system permits unlimited angling, and therefore provides views that have greater interpretability. Additionally, the nonmounted system reduces or eliminates the need to move the subject to the unit, thereby permitting radiographic examination in virtually any remote location, such as within a tomb or a cave.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

One particular unit that has been a real workhorse for our paleoimaging team is a 1952 Picker Field Army Unit that was originally used in the Korean conflict and is designed for rugged environments. The unit has two functional pieces and requires two carrying/ shipping cases, creating the need to add baggage-handling costs to each project. Another drawback is that it weighed over 80 lb! We now use a much lighter single-piece unit, the previously mentioned MinXray HF 100/30 veterinary unit. Utilities When using radiography in the field, electrical requirements for the equipment must be considered. Often, in remote regions there is no electricity. In other areas there may be electricity, but at best only fluctuating output during certain hours of the day, depending on factors such as the time of year and reservoir water levels required for power generation. We recall one unique power situation in Tucame, Peru, in which our power requirements were such that when we activated the radiographic equipment, the nearby town would experience a transient “brown out”! Although electric power may be available, it may be a different voltage than required by the radiographic instrumentation. With these and other unexpected situations related to available power, researchers need to learn as much as they can about the available power and remain flexible with their protocols. In cases where there is no power available, a gasoline- or diesel-powered 5000 W generator is the best option. When relying on a generator, it is important to estimate the potential usage and determine the additional fuel needs for the generator itself. These units are quite heavy and may require transportation into remote regions where no vehicle can travel. This can be accomplished either by carrying the generator or by fashioning a travois, which may be hauled by a beast of burden. In either case, additional manpower will be required for this task. In the case of travois transport, a mule wrangler may be needed as well. The generator is also useful as a backup power source in those regions where the electric power is only active during certain hours of the day. In most countries, electricity is supplied at 220 V at 50 Hz (hertz or cycles per second). Equipment manufactured in the United States is designed for 110 V at 60 Hz. In order to use the lower voltage units outside the United States, an electrical transformer is required to adjust the current. Traveling with a transformer can be challenging, as it tends to add considerable weight to the overall equipment being transported. Newer transformers are available that are much lighter and, therefore, more practical. Another important “utility” to consider is water. The availability of water for film processing is critical, as it is required to rinse conventional x-ray film once processed. Access to an ample water supply may be a challenge or, in some cases, the use of the local water may even reduce drinkable water supplies. Additionally, the particulate and mineral content in some local water may impact the final image when processing conventional film. The pH of water with a high mineral content may affect the chemistry used in manual processing. Since the fixer is acidic, the higher pH of the water will tend to neutralize the fixer and require more frequent replenishment of the chemical. In one remote location in the Osmore River Valley near Ilo, Peru, in an effort to conserve water and to create water that was free from minerals, we proposed and designed a water distillation system.

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X-Ray Tube Support System The x-ray tube will often require some mechanism by which the tube is suspended over or placed under the subject of study. The decision of where to place the x-ray tube should depend on a combination of concern for the fragility of the subject and, often more importantly, convenience. Although commercial support systems are available, they may weigh as much as a 100 lb (45 kg), adding extra unnecessary weight. Designing supports for the x-ray tube is a creative process; they can be a formal arrangement of specific metal tubes or an informal contraption that is made from whatever you have available to you. A formal x-ray tube support system can be constructed from a series of aluminum electromechanical tubes (EMT) cut into 20 in. (50 cm) sections. Once the EMT system has been constructed, the x-ray tube can be secured to the support with duct tape or another suitable clamping system (Figure 2.5). This formal EMT system has the advantage of being flexible in its possible configurations and is quite sturdy, which is important with some of the heavier x-ray tubes. The major disadvantage is that the system, even when dismantled, is heavy and cumbersome, making transportation a greater challenge. Additionally, the set-screws in the hardware used to join the EMT sections can strip, requiring spare parts to be included with the supplies transported to the site. Informal x-ray tube support systems can be fashioned with common items such as sawhorses, wooden posts, construction rebar, rocks, equipment cases, stacked chairs, and ladders found at the research location (Figures 2.6A and 2.6B). Instead of positioning the

Figure 2.5  The electromechanical tubing (EMT) frame supporting the x-ray tube (arrow).

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.6A  The x-ray tube fastened to the pole with duct tape.

x-ray tube for anterior-posterior projections above the remains, the radiation source can be placed on the floor with the beam directed up for posterior-anterior projections (Figure 2.7). Since duct tape always seems to play a major role in the design of these informal x-ray tube support systems, sufficient quantities should be included with supplies.

Figure 2.6B  X-ray tube placed on stacked chairs for a lateral projection of a mummy.

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Figure 2.7  X-ray tube placed on the floor to project the x-ray beam vertically through the skull of the mummy called James Penn. The EMT frame was used to support the film holder.

Image Receptors As described earlier in this chapter, image receptors come in a variety of shapes and sizes, and have set technical factors. Discarded cassettes can be easily found at medical centers or imaging equipment vendors. Optimally, a 14 × 17 in. (35.5 × 43 cm), 100-speed screen would be the best all-purpose choice. This size would cover a large area of the mummy or artifact, and if disarticulated skeletal remains are the study subjects, a number of bones will fit onto a single film. A 14 × 36 in. (35.5 × 91.4 cm) cassette would be a great find. Although that size film has become more difficult to locate (trifold versus single sheet), the greater challenge is loading it into the hanger for manual processing. The cassette can be loaded with two sheets of standard 14 × 17 in. (35.5 × 43 cm) film with 2 in. of screen uncovered (Figure 2.8). The primary advantage of the long cassette is that it covers a large area of the mummy in a single exposure. The principal disadvantage is that generally an SID of 72 in. (190.5 cm) is necessary for the radiation to cover the entire 14 × 36 in. (35.5 × 91.4 cm) cassette. Conventional radiographic film/screen imaging systems can be problematic. Although expired film can be easily obtained, it may be difficult to match the speeds of the donated screens with expired film. The main disadvantage of a mismatched system is a change in the relative speed and, possibly, a loss of detail. However, if the film and the screen were donated, the financial savings are certainly worth the loss of a little detail and contrast. When detail is necessary, such as an infant bundle, a nonscreen film holder should be used instead of the cassette equipped with intensifying screen. The resulting image will have greater detail and the textile wrappings and some soft tissue structures may be more clearly visualized (Figures 2.9A and 2.9B). If a nonscreen film holder cannot be located, one can easily be fashioned using the black plastic liner found in boxes of many brands of

40

Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.8  Two 14 × 17 in. (35.5 × 43 cm) films placed into a 14 × 36 in. (35.5 × 91.4 cm) cassette. Note there were 2 in. (5 cm) on the right side of the cassette, where there is no film.

x-ray film (Figure 2.10). If the black bag liner is not available, one can be easily constructed. Cardboard or 1/8 in. (3.1 mm) Foamcore® can be used as a “stiff” base. The base is then placed into an “envelope” made of black swimming pool liner. The simple black bag film holder without the cardboard or foamcore has the advantage of being more flexible. Using film without a cassette or screen has various applications. If the space behind the subject is too narrow to allow the passage of a cassette or there is no way to support the cassette behind the subject, nonscreened film can be slid into that space (Figure 2.11). The flexibility and lightweight nature of a nonscreen film holder can be utilized for projections, such as a lateral skull, that could not have been taken without a more complex, timeconsuming approach (Figures 2.12A and 2.12B). Another application is when the goal is to image a very large area at one time. Using nonscreened film and allowing the film to overlap so that the images may be reconstructed during postprocessing will produce a single image of the large subject. The drawback to the nonscreened method is that the exposure time needs to be increased by a factor of 100. If a single long exposure were taken, the x-ray tube would overheat and result in permanent damage. Many shorter exposures must be

Figure 2.9A  An AP (anterior-posterior) projection of the pelvis and legs of a Guanajuato infant mummy (M1M3) taken with a Polaroid screen cassette at 46 kVp and 1.2 mAs.

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Figure 2.9 B  A similar projection of another Guanajuato infant mummy (GMO8), taken with-

out the use of a screen, on Polaroid film at 46 kVp and 150 mAs. Note the more defined appearance of the trabecular pattern in the right ilium with the nonscreen image. In addition, the film taken without the use of the screen provides visualization of the soft tissue structures of the legs.

taken to avoid the overheating potential, and additional care must be taken to keep the x-ray tube cool. The authors have used ice, cool packs, and in one case, chilled champagne to keep the tube cool (Figure 2.13). Another image receptor system that was available, instant film, will be discussed following the description of film changing and processing challenges. The instant film eliminated many of these challenges, thereby streamlining the conventional imaging procedure.

Figure 2.10  An old commercially available nonscreen film holder on the right and the black plastic envelope removed from a box of film on the left. The latter can be used as a nonscreen film holder.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.11  Since the mummies were fastened to the wall, it was not possible to place a conventional cassette behind the mummy. Here, a Polaroid film packet was easily placed behind the thorax of a mummy (U1) in Urbania, Italy.

Darkrooms The major disadvantage of conventional film is that it is light sensitive, and cassettes must be loaded and unloaded in a light-tight place. We describe the use of both informal and formal darkrooms, as well as portable darkroom construction at the field site. An informal darkroom or film-changing space can be created in a very short time at the location of the imaging study. A room, such as a bathroom or even a closet, can often be easily rendered light tight (Figure 2.14). Black gardening plastic or black pool liner held

A

B

Figure 2.12A  Positioning for a lateral projection of the skull of a mummy in Urbania, Italy. The nonscreen film holder (A) was held in place by the tape. The x-ray tube (B) was placed on a pile of boxes for the exposure.

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Figure 2.12B  The resulting Polaroid image of the standing mummy in Urbania, Italy. Note the extreme wear on the maxillary molar (arrow).

in place by duct tape will eliminate light from windows and around doors with particular attention given to door jambs (Figure 2.15). More inventive light-tight film changing spaces were created within museum displays, a circular staircase leading from a museum up into a cemetery, bathroom stalls, and a church confessional (Figure 2.16). Exposed films can be stored in a light-tight transfer case (BarRay®) that resembles a briefcase. These containers can easily hold about 100 exposed films and can be transported to an automatic processor in a formal darkroom. Formal darkrooms may be located at medical facilities, universities, and chiropractic, podiatric, and veterinary practices. Many of these facilities have automatic film processors within their darkrooms. Since processing images of remains will not have precedence over patient or client images, using established automatic, or even manual processing facilities,

Figure 2.13  Cold packs taped the either side of the x-ray tube to cool the unit during multiple

exposures.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.14  An example of a “native hut” in a museum in Iquique, Chile, that was turned into a darkroom to load and unload cassettes. In order to make the space light tight, the inside of the window (arrow) of the hut was covered with black plastic and a door was fashioned with black felt. Incidentally, the felt, acquired from a local fabric shop, had a Christmas tree and star pattern that was fluorescent. However, the wavelength of the light given off by the fabric did not fog the x-ray film.

Figure 2.15  Black plastic used to cover the window in a bathroom.

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Figure 2.16  Material (arrow) placed over the door of a confessional in a church in Moquegua, Peru, to convert it into a light-tight film changing “room.”

must be scheduled for a specific time of day. Depending on the volume of films processed per day, the quality of the developing chemistry can change during a particular day or after a certain number of films has been processed. Therefore, large numbers of films processed at once, commonly termed batch processing, can be problematic. First, test exposures should be taken bracketing the exposure setting, meaning that an exposure should be made with what would be the expected mAs. Next, a second exposure is taken with half the mAs and then a third exposure with double the mAs. All three images are processed at the time of day that the batch processing would take place. From the processed images, the best exposure setting is noted, and that becomes the mAs that will be used in the field imaging project. Usually, the processing facility is a minimum of several miles or kilometers from where the study is taking place, and trips to process the films can be very time consuming. Even if the technical factors result in an acceptable image, a film may need to be repeated due to poor positioning or an inadequate demonstration of a particular anatomical or pathological feature. Repeat imaging drastically slows down the progress of the study and may severely limit the number of specimens examined. If there is no place to create an informal darkroom, and no formal darkroom is available, a portable darkroom can be constructed. Although there are commercially available portable darkrooms, they are typically designed for standard photography and are too small for the needs of x-ray film processing. A portable darkroom can be constructed using precut PVC pipe with the appropriate connectors as the framework (Figure 2.17). An 8 × 3 ft (2.4 × 0.9 m) length of black felt is first draped over the front to act as the first layer of the

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.17  The PVC pipe frame for the portable darkroom.

door (Figure 2.18). A second layer of black felt is laid over the first layer to create a double door to ensure a light-tight opening. The entire frame is then covered with light-tight material and secured in place with clamps (Figure 2.19). If it is designed well, there is room for extra film and the three necessary processing tanks. The authors have used this darkroom

Figure 2.18  Two layers of felt are used to create a light-trap door.

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Figure 2.19  The entire PVC pipe frame covered with two layers of black plastic at right angles to each other.

successfully on such remote locations as on a rooftop and adjacent to a Buddhist temple. If you really want to get fancy, an entry fly can be affixed to the door end to provide shade (Figure 2.20). Film processing, too, must be considered. If only eight to ten 14 × 17 in. (35.5 × 43 cm) films are going to be processed per day, three large plastic photographic trays would suffice for the chemistry. If more than ten films per day are going to be processed, a conventional manual x-ray film processing workspace must be constructed. The easiest method would

Figure 2.20  The portable darkroom was covered with a “space blanket” to provide a reflective surface and a tent fly to shield the entrance.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

be to acquire a stainless steel tank system designed for this purpose. Until recently, small chiropractic, podiatric, and veterinary practices manually processed their x-rays. Once they converted to automatic processing, their used wet processing tanks were discarded. These units may be available from local radiographic equipment dealers. Generally, these units consist of two 5-gal tanks, one for developer and the other for fixer, that sit within a much larger, approximately 20-gal tank that would be filled with water. The water tank served several purposes. It was used to wash the film after development and fixing, and it also maintained the temperature of the chemistry. The large tank usually was directly connected to the water supply so that a continuous flow would eliminate contaminated water and also wash the fixer from the film before it went to the dryer. Since the water/wash tank is so large, it is not practical to transport to a field facility, particularly if it is outside the continental United States. A more appropriate approach would be to acquire three 5-gal stainless steel tanks, one each for developer, fixer, and water. The latter would only be used as a wash between the developer and fixer. As a cautionary note, many of the 5-gal tanks have a cork located on the bottom of the tank to permit drainage. When submerged in the larger tank, the cork does not present a problem. However, if the tanks are used independently, they must be placed on a rack with thickness equal to the thickness of the cork or they will be unstable. Another option is to construct three tanks out of marine plywood. The wooden containers are nearly indestructible and would also serve as sturdy transport boxes to bring material to the site. To transform the plywood boxes into watertight tanks, the authors fabricated a liner from heat-sealed vinyl roofing material (Figures  2.21A and 2.21B). A fiberglass liner would also serve the same purpose. The three processing tanks need to have lids to avoid evaporation, which would cause a change in the chemical concentrations. It is important to place the tanks in order of use in the developing process and to secure the tanks to avoid knocking them over in the dark (Figure 2.22).

Figure 2.21A  Vinyl roofing material heat-sealed to create a liner for plywood tanks.

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Figure 2.21B  The vinyl liners within plywood processing tanks. A PVC pipe (arrow) was placed on the faucet to permit better flow into the wash tank.

A final wash tank would have to be devised on site. The easiest approach would be to use a 30-gal plastic container with a hose to provide continuous water flow (Figure 2.23). If an electrical power supply is available, a circulating water pump can be placed into the container to move the water within the tank. Film Drying and Viewing Film drying is a pretty straightforward and logical procedure. Simply string a clothesline either inside or outside the building, and hang the film on it with clothespins. Drying inside the building has the advantage of minimizing debris attachment to the wet surface before the films are completely dry. It can also be done regardless of the weather. Film viewing in the field is usually accomplished “al fresco.” Simply hold the film up to the sun or a bright light and begin interpreting the data.

Figure 2.22  Plywood tanks positioned within the portable darkroom.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

C

B

A

Figure 2.23  A 30-gal container (A) that was used as a wash tank in Leymebamba, Peru. Note the film hangers (B) resting on the post, the lead apron (C) hanging on the post, and the x-films drying on the clothesline.

Instant Film At this point it should be clear that conventional film has a number of disadvantages in a field application. Even though large quantities of film may be easily acquired as a donation, the need for a darkroom, chemistry, and water make it tremendously problematic. In addition, even if automatic processing is available, the occasional need to repeat films will result in the examination of fewer specimens. Because x-ray and visible light are both forms of electromagnetic radiation, photographic films and papers used for photographic prints can be used to record radiographic images. Since Polaroid provided a solution for medical imaging over 50 years ago, it seemed the logical choice. Through the mid-1980s, old Polaroid medical imaging systems could be found in storage at many major medical centers. In a 1986 study of a mummy known as the “Soap Lady” at the College of Physicians Mütter Museum in Philadelphia, Pennsylvania, the Polaroid system made it possible to complete a radiographic examination of the mummy on-site (Conlogue et al. 1989). Although several medical imaging centers were within a few miles of the museum, the mummy was too fragile to be transported. A donated 30-year-old x-ray unit was brought to the site for the study, but processing the images would have to be done at a medical center. Since the relative speed of Polaroid intensifying screens matched the speed of the conventional radiographic screen cassette, the exposure factors for different regions of the

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Figure 2.24  The 4 × 5 in. (10 × 12.7 cm) Polaroid Type 53 film of a femoral head and neck. Note the detail resolution of the trabecular pattern.

body were established with the Polaroid system. Using the Polaroid technical factors, over a dozen conventional 14 × 17 in. (35.5 × 43 cm) radiographs were obtained without having to repeat any exposures. Unfortunately, Polaroid discontinued the manufacturing of the film for its imaging system in 1990. In 1997, once again the need for a nonconventional radiographic film recording media was necessary for the establishment of a field radiographic facility at an anthropological site in Peru (Conlogue and Nelson 1999). Polaroid Type 53 photographic film provided a partial solution to the problem. Since it was a film intended for photographic applications, it could not be used with an intensifying screen, but only as a nonscreen image receptor. The two major disadvantages were that nonscreen imaging required extremely long exposures, often many seconds long and the limited size of the 4 × 5 in. (10 × 12.5 cm) film. However, the film was large enough to image small structures, such as a femoral head to determine trabecular patterns in age determination (Figure 2.24) or mandibles to access dental development and pathology (Figure 2.25). Although it did not completely eliminate the need for conventional radiographic film, it did reduce the number of films that needed to be processed and established the value of Polaroid in the field. A representative (Phalen 1998, personal communication) for a Polaroid distributor suggested a larger-format (8 × 10 in. [20.3 × 25.4 cm]) product that could be used with an intensifying screen system introduced in 1984 and manufactured by Calumet Photography. The system, targeted for use by veterinarians, podiatrists, and bomb squad personnel, also had two types of film available. Because the films were photographic products, the film sensitivity was indicated in ISO (International Organization for Standardization) and the European equivalent DIN (Deutsche Industrie Norm) units (Redsicker 2001). The faster the film, the higher the ISO/DIN. Unlike x-ray film, which is orthochromatic, that is, sensitive to only specific wavelengths of light, photographic film is panchromatic and therefore reacts to the entire spectrum of visible light. Type 804, Polapan Pro 100, was the slower, more detailed film (100 ISO) described as a glossy finish, medium contrast with a key application identified as professional photography proofing (Polaroid, a). Type 803 (800 ISO)

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.25  Three views of an infant mandible on 4 × 5 in. (10 × 12.7 cm) Polaroid Type 53

film.

was described as a high-speed, glossy finish, medium contrast with a broader range of key applications including microscopic imaging, copy stand photography, and x-ray bomb detection (Polaroid, b). The authors have used both the Type 804 and the Type 803 in field imaging settings with excellent results. It is important to realize the differences in the application of the two Polaroid Type films. The slower speed, Type 804, loaded into the cassette provided excellent detail. Since Type 803 is more sensitive, it was better suited for situations when there wasn’t sufficient space for the cassette and the nonscreen approach was necessary. For example, if the technique required for a Type 804 film loaded into the cassette required a 2 s exposure, that same film would need 200 s for the same nonscreen exposure. However, because the Type 803 requires 1/8 the exposure time as the Type 804, only a 25 s exposure would be necessary. Not only is less time required to produce the image, but also the reduced exposure time has the additional advantage of prolonging the life of the x-ray tube. In a laboratory situation, an object or specimen similar to that which will be encountered in the field can be used to determine the optimal exposure factors for the Polaroid and conventional radiographic film/screen systems. A conversion factor can then be calculated. Once in the field, the appropriate technique can be determined with the Polaroid system, the conversion factor applied, and a series of conventional films can be taken with the adjusted technique. At the end of the day, the exposed films can be transported to a facility for batch processing, saving valuable on-site research time.

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There were three drawbacks to using Polaroid film as a field image receptor: limited size (4 × 6 or 8 × 10 in.; 10 × 15.2 or 20.3 × 25.4 cm), cost (about $15.00 per sheet for the larger size), and the need to ship it to the country where the study was to be conducted. The cost made it prohibitive for large-scale projects. Even with those considerations, the instant film yielded excellent detail and eliminated the need for a darkroom and wet processing chemistry. The ideal system for fieldwork would be a filmless digital x-ray system, which will be discussed in Chapter 3. However, recently an even greater disadvantage materialized. As of May 2008, Polaroid stopped manufacturing Type 804 and 803 films. The experience with the Polaroid suggested that other photographic products may also provide satisfactory images. In order to eliminate the problems associated with shipping materials outside of the United States, a photographic product that would be available universally was sought. It was decided to test Ilford MGIV photographic print paper. As a photographic product, it was sensitive to a panchromatic spectrum of light similar to the Polaroid photographic products. As a comparison, one sheet of the 8 × 10 in. (20 × 24.5 cm) Ilford paper was loaded into the Polaroid cassette, and another sheet loaded into a 100speed conventional radiographic cassette. Following each exposures, the paper was placed into a cylindrical Unicolor eight real day light processor (Figures 2.26A and 2.26B) and developed with Ilford PQ Universal developer with agitation of 30 s. The developer was drained and fixer poured into the tank and agitated for another minute. After the fixer was poured off, the paper was washed in the tank for 5 min. The resulting images demonstrated that the Ilford paper placed into the Polaroid cassette provided an excellent image (Figure  2.27A). However, because the conventional radiographic screen emitted orthochromatic light, the resulting image with the Ilford paper in the x-ray film holder was unsatisfactory (Figure 2.27B). An additional test was carried out with the Ilford paper in a nonscreen film holder (Figure 2.28) with excellent results (Figure 2.29). It certainly would be impractical to carry out an entire study using the photographic print paper; however, the paper has several applications. Once the satisfactory kVp and mAs, have been established for the photographic paper, a conversion factor for conventional radiographic film can be calculated. This reflects the procedure described previously for the 1986 study of the Soap Lady. In addition, “on-the-spot” images can be obtained to check positioning before conventional radiographs are taken. If the positions need to be altered, it can be done without the delay of having to wait for the conventional radiographs to be processed.

Figure 2.26A  Unicolor ® day light processor.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.26B  Photograph showing the orientation of the Ilford photographic paper (arrow) within the Unicolor ® tank.

Figure 2.27A  Lateral skull radiograph using Ilford photographic paper loaded into a Polaroid

cassette.

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Figure 2.27B  Lateral skull radiograph using Ilford photographic paper loaded into a cassette with conventional radiographic intensifying screens.

Figure 2.28  Positioning the Ilford paper in a nonscreen film holder.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.29  Lateral skull radiograph with Ilford paper loaded into a nonscreen film holder.

Positioning Even if the most sophisticated facilities are available, poor positioning of the remains will render the images of little value. Proper positioning can minimize the effects of superimposition of shadows, one of the principal disadvantages of conventional radiography. Wrapped mummified remains present the greatest challenge, particularly if they are in a flexed position. Without the ability to visually identify landmarks, the first image only documents the relative position of internal structures. From that x-ray, a skilled radiographer should be able to determine how to manipulate the mummy bundle to achieve the required position. Even if the remains are in an extended position, subtle manipulation of the remains may be required. For example, if a suspected structure, such as a fracture, is noted on a projection (Figure 2.30A), the body can be rotated into an imaging perspective that will more clearly visualize the region in question (Figure  2.30B). In situations where the remains cannot be safely rotated, the x-ray tube and the image receptor can be positioned to achieve the same results (Figures 2.31A, 2.31B, and 2.31C). For skeletal material, the task is less formidable. Since the bones can be placed directly onto the image receptor, there should be no questions as to the position. For both the mummified and skeletal remains, imaging projections should be identical to those used in medical imaging. There are volumes dedicated to describing proper position methods (Frank and Ballinger 2003) for the entire body, and the information should be used as references for any paleoimaging study. The most valuable projection of the skull is the lateral. In many cases, it will reveal characteristics that indicate the sex of the individual, such as presence or absence of a

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Figure 2.30A  An AP radiograph of the right hip of a Guanajuato mummy (MH7) with an apparent fracture (arrows) of the pelvis.

browridge and external occipital protuberance, and it will provide an overview of the dentition. To obtain a lateral projection of the skull, the interpupillary line should be perpendicular (Figure 2.32A), and midsagittal lines should be parallel to the image receptor (Figure 2.32B). Positioning can present a problem in cases where there has been intentional cranial modification. In order to more completely evaluate the dentition, right and left oblique projections of the mandible and maxilla may be necessary. However, to obtain these views, particularly on flexed remains, a great deal of manipulation of the x-ray tube and image receptor will be necessary (Figure 2.33). For the optimal images, the side of the mandible and maxilla of interest should be parallel to the image receptor. The opposite side should be rotated to eliminate superimposition. There are several methods to acquire an anterior-posterior (AP) (Figures 2.34A and 2.34B) or posterior-anterior (PA) (Figure 2.35) projection of the skull. Taking into considerations the objectives of the study, a radiologist should be consulted to determine which projection would most clearly demonstrate the structures desired. In cases of mummified remains, an AP or PA and lateral projections of the chest and abdomen should be acquired. Although dehydrated soft tissue structures are not usually visualized on conventional radiographs, when those tissues are calcified, such as lymph nodes or plaque within arteries, they are clearly seen (Figure 2.36). The lateral view will not only provide a second projection to assist in determining the spatial location of any

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.30B  With the body rotated, the extent of the fractures (arrows) became clearly delineated.

Figure 2.31A  An AP chest radiograph taken of the Soap Lady mummy at the Mütter Museum of the College of Physicians. Because the radiograph is a two-dimensional image, it is not possible to determine the exact location of the large radiopaque object in the chest.

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Figure 2.31B  Because the mummy could not be rotated, the cassette (arrow) was angled beneath the table to obtain an oblique projection.

Figure 2.31C  The oblique radiograph of the chest conclusively demonstrated that the radiopaque object (arrow) was located outside of the mummy’s body along the posterior aspect of the back.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

B

A

Figure 2.32A  For a lateral projection of the skull, the interpupillary line (A) should be per-

pendicular to the plane of the film (B). Although there appears to be a great deal of distance between the skull and the film, with a slow speed intensifying screen, the image will be magnified without a tremendous loss of detail.

A

B

Figure 2.32B  The midsagittal line (A) should be parallel to the plane of the film (B) to minimize rotation on a lateral skull projection.

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C B

A

Figure 2.33  Since the mummified remains are immobile, positioning for an oblique mandible is complex. The center ray of the x-ray beam (A) must be directly beneath the side farthest from the film. To enhance separation of the mandibular bodies, the plane of the film (B) should be slightly angled, 15° to 20°, from a plane parallel to the sagittal plane of the skull (C).

calcifications but will also afford a prospective of the spine with less superimposition (Figure 2.37). The mummy’s joints, including shoulders, wrists and hands, hips, knees and ankles, should also be radiographed. An attempt should be made to obtain as close as possible to AP or PA projections of the joints to document degenerative changes. With the exception of remains in a flexed position and possibly hands and wrists on extended mummies, C

A

B

Figure 2.34A  For an AP projection of the skull, the line extending from the outer canthus of the eye to the external auditory meatus, known as the canthomeatal line (A) should be perpendicular to the plane of the film (B). The center ray of the x-ray beam (C) should be directed through the midpoint of the browridge, the glabella, and perpendicular to the film plane.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.34B  The resulting AP skull projection. It will be noted that the orbital content in this projection is obscured by the petrous ridges projected into the structure.

superimposition should not be a problem. In order to eliminate superimposition, a nonscreen film holder may be placed underneath the hands and wrists (Figures  2.38A and 2.38B). Devices to Maintain the Position of the Remains As previously stated, proper positioning is required to obtain the most information from a radiographic image. However, to acquire that image, both the remains and the image receptor must maintain the precise position during the duration of the x-ray exposure. Cardboard and other solid materials are radiopaque, impeding the passage of x-rays and causing the material to be visible on the processed radiograph. The positioning aid must be radiolucent, or “nearly invisible,” to x-rays. There are commercially available foam shapes such as wedges and blocks that are used routinely in imaging facilities (Figure 2.39), but they are expensive and bulky to transport. Generally, foam pads can be purchased in any large city or town near to where the study will be completed. Foam pads of various thicknesses can be purchased and then cut into required shapes (Figure 2.40).

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C E

B

D

A

Figure 2.35A  Positioning for a PA Caldwell projection of the skull. The canthomeatal line (A) should be perpendicular to the film plane (B). In order to achieve the correct angle, a commercially available positioning aid (C) was placed between the skull and the cassette. The center ray of the x-ray beam (D) was directed to form a 15° caudal angle to the canthomeatal line (A) and exited through the glabella (E).

Figure 2.35B  Unlike an AP or PA skull where the petrous ridges are projected within the orbits, in an AP or PA Caldwell projection the petrous ridges (A) are found near the inferior margins of the orbits.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

A

B

Figure 2.36  An AP chest radiograph of George/Fred demonstrated two radiopaque structures (A) that were suspected to be calcified hilar lymph nodes. The second object (B) appeared to be a coin within the chest.

For skeletal remains, positioning aids are also necessary. Since only minor adjustments may be required and individual bones are not very heavy, small pieces of foam padding will achieve the desired results (Figures 2.41A and 2.41B). Devices for Holding the Image Receptor The image receptor, or film–screen system, holding device requires careful consideration and creative design in order to obtain the position required. At established imaging centers, standard devices are built into the fixed system and lack the flexibility that may be required to obtain the necessary projections. Historically, radiographers conducting portable radiographic procedures in a patient’s room or trauma cases in emergency room situations may have been challenged to improvise an image receptor holding device, such as a wastebasket (Figure 2.42). In the field, the film-holding device can be constructed from materials at or near the site. Sometimes, what is required can be found in dumpsters. Cardboard and duct tape generally seemed to factor strongly in the design and configuration of many of the filmholding devices in the field. Cardboard boxes with tunnels cut through them to pass the subject through work quite as well as film holders (Figure 2.43). Since it can be easily cut to desired lengths, PVC pipe can be used as a film-holding device. Lengths of pipe can also be easily angled, allowing for various projections (Figure 2.44). When using a suspended x-ray tube support system, the subject can be placed on spacers, allowing the film to be placed underneath the subject (Figure 2.45). Creative film-holding devices require ingenuity, critical thinking, and common sense. For example, the device needs to be flexible and also sturdy enough not to collapse onto the subject under study. One can even construct a suspended sling from string, cloth, or rope

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B

A

Figure 2.37  Lateral chest radiograph confirming that the two radiopaque structures (A) were calcified hilar lymph nodes and that the coin (B) was within the chest cavity.

to hold the film above the subject (Figure 2.46). Using these varied film-holding methods, nearly every clinical position can be replicated and data regarding anatomical structures can be collected. Given the creativity required to apply conventional radiography in a field situation, several unique technical challenges may arise. The following technical challenges and their solutions are intended to stimulate the reader’s mind and broaden the scope of application of conventional radiography.

Unique Technical Challenges Field imaging by its very nature is conducted in poorly controlled conditions under unpredictable circumstances. The paleoimaging team needs to be aware of and anticipate many unique challenges in order to accomplish the objectives of a given imaging study. Efforts need to be made to be efficient and creative in an attempt to conserve resources and collect the best possible images. Experience-based challenges to field imaging research with problem resolutions are presented below.

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Figure 2.38A  An AP pelvis radiograph of George/Fred with the left hand superimposed over the ilium, sacrum and coccyx.

Multiple Images on One Film  Since x-ray film is a precious commodity in the field, as much of the film surface as possible should be utilized. An example of this situation is apparent when the objects to be imaged are smaller than the x-ray film, such as individual bones from a disarticulated skeleton. Although disarticulated skeletal components present less complex imaging challenges than experienced in the examination of mummified remains, careful planning is still necessary. In order to optimize film use, several objects of similar density can be placed on the surface of a cassette film holder, and a single exposure can be taken to produce an image of multiple components.

Figure 2.38B  A nonscreen Polaroid image of the left hand.

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Figure 2.39  A skull being stabilized with commercially available radiolucent positioning

devices.

If multiple projections of a singular skeletal component, such as a skull, or images of multiple objects that vary in density are desired on a single sheet of film, each object may be exposed individually. The procedure is achieved by dividing the film into sections, such as halves or quadrants, with the unexposed sections being partitioned by lead shielding. In order to minimize the weight of the equipment that is transported to the field site, local shielding materials, such as rocks or concrete blocks found at the study site, can be substituted for the lead shielding. After the first exposure, the exposed area is covered, and the next section of the film to be used is uncovered. The procedure is repeated until the entire

Figure 2.40  Foam purchased locally in southern Peru used to position this Chiribaya mummy.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts A

C

B

Figure 2.41A  The cervical, thoracic, and lumber vertebrae were positioned for a superior-

inferior (SI) projection. Small pieces of foam (A) were employed to stabilize certain vertebra and ensure that the vertebral bodies were parallel to the film plane. Note that the number of the specimen (B) in lead numerals was placed on the cassette along with a marker (C) to indicate the right side.

surface of the film has been utilized (Figures 2.47A and 2.47B). A simple grid system using tape can be designed on the surface of the film cassette to ensure there will be little or no double exposure situations. Low-Density Objects: Too ἀ in  Taphonomic conditions, such as an acidic peat bog, will decalcify remains, rendering the skeletal system nearly radiolucent. This decalcification reduces the density and renders any residual bony structures virtually invisible to x-rays when using standard exposure settings. A pair of bog mummies, found in 1904 near the town of Weerdinge and now in the collection at the Drents Museum in Assen, the Netherlands, was the focus of a field radiographic examination (Death in a Bog 2002). The minimum factors that could be set on the 1952 vintage Picker Field Army x-ray unit used

Figure 2.41B  The resulting radiograph of the vertebrae positioned for the SI (superior-inferior)

projection.

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B A

Figure 2.42  A wastebasket (A) can serve as a satisfactorily cassette (B) support for a cross-table radiograph where the x-ray (C) is directed horizontally.

in this study were 45 kVp, 10 mA, and 1/2 s. Even at the lowest settings, the exposure was too much to demonstrate the low-density structures resulting in an image that showed no evidence of skeletal structures (Figure 2.48). There are two conventional approaches to reducing the x-ray output or the mAs. The first is to directly decrease the mAs. However, since the mA was already at the lowest setting, exposure time was the only other factor that could have been reduced. Unfortunately, because the timing device was a spring-loaded mechanism similar to a common egg timer, there was no way to reliably lower the time setting with any accuracy. A second approach to decreasing the exposure is to increase the distance. If the distance could be doubled from 40 in. (101 cm) to 80 in. (203 cm), the quantity of radiation reaching the image receptor would be quartered (see inverse square law). However, there was not sufficient tubing material to raise the x-ray source up to 80 in. (203 cm) (Figure  2.49). After noticing a black

Figure 2.43A  A cardboard box cut to form a tunnel to pass the mummy through.

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Figure 2.43B  Mummy within the cardboard tunnel and a cassette (arrow) positioned on top

of the tunnel.

aluminum material that was used for lighting, it was decided to create a filter using the aluminum. Several layers of the material were taped over the x-ray tube aperture (Figure 2.50), which effectively absorbed about 50% of the lower energy portion of the x-ray beam before it reached the mummy (Figure 2.51). This resulted in a satisfactory exposure, adding valuable data to the imaging study. Cannot Get Two Views, or When Two Views Just Are Not Enough  As previously stated, radiographs are two-dimensional images of three-dimensional objects, and at least two projections or views are necessary to provide an idea of the spatial orientation of structures within a body. However, even with a second projection at 90°, superimposition can still make it difficult to determine the relative position of objects. Photographs have always

B

A

Figure 2.44  PVC pipe was used to produce the angulated frame to support an x-ray cassette (A) held in place with duct tape. The x-ray tube (B) was resting on the table in order to achieve the necessary angulation of the x-ray beam.

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A

B

Figure 2.45  Two 1 × 3 in. (2.5 × 7.5 cm) pine boards (A) provide the space required to form a “tunnel” beneath the mummified remains to accommodate the cassette (B).

had a similar problem in separating objects from the background, middle ground, or foreground. In 1843, Sir David Brewster invented the lenticular or refracting stereoscope, which was adapted into the hand stereoscope used in photography (Eisenberg 1992c). Since over 50 years had elapsed before Roentgen’s announcement of his discovery, it wasn’t long before the popular illusionary photographic method would be applied to x-ray imaging. In March

Figure 2.46  A tape sling used to support the Polaroid cassette above the chest of a mummy in Guanajuato, Mexico.

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Paleoimaging: Field Applications for Cultural Remains and Artifacts

Figure 2.47A  Rocks utilized to permit multiple exposures on a single cassette.

1896, Elihu Thomson suggested using the stereoscopy in radiology (Eisenberg 1992d), and it was quickly adapted for complex anatomical regions such as the skull, chest, and pelvic areas (Files 1962a). Prior to the advent of other modalities, particularly computed tomography, stereoradiography was routinely taught to student radiographers. As with many radiographic procedures, there are several approaches to obtaining stereoradiographs. The first, and most common, requires a linear shift of the x-ray source at a ratio of 1:10 (Files 1962b; Cahoon 1965a). If the SID is 40 in. (101 cm), then the total tube shift should be a total of 4 in. (10 cm), 2 in. (5 cm) in either direction from center. For optimal results, the direction of shift was specified to be at right angles to the predominating lines of the part being radiographed. The “predominating lines” in the thorax are the

Figure 2.47B  A radiograph of two cervical vertebrae where rocks were used to permit three positions on a single film.

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Figure 2.48  The overpenetrated and overexposed initial Polaroid image of the left arm of the Weerdinge mummy.

Figure 2.49  The set-up for the Weerdinge mummy study. The x-ray tube was at the maximum distance from the mummified remains.

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Figure 2.50  Several layers of the black aluminum (arrows) were taped over the window of the

x-ray tube.

Figure 2.51  The resulting radiograph after the beam had been filtered. The radius and ulna were clearly visible.

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B

A

Figure 2.52  A Stanford x-ray stereoscope. One of the pair of images was placed on each view box (A) and aligned while looking through the viewer (B).

ribs, so the direction of the shift should be longitudinally, along the vertebral column. For stereo images of the long bones, the shift would be transversely across the bones. Since the skull is a complex structure with bony components along several planes, it is the exception, and the shift may be in either direction depending on which structures are to be visualized (Cahoon 1965b). Stereoradiography was routinely employed in chest radiography prior to the advent of computed tomography. This was a common procedure, particularly during the period when tuberculosis was epidemic in the United States. Stereo viewing devices were constructed specifically for viewing the image that provided a “suggestion” of depth of field (Figure 2.52). There are two important considerations in acquiring satisfactory stereo projections. The first requirement is that the object under examination must not be moved between exposures. To achieve this goal, the object must be elevated to create a space to accommodate the film. If there is an x-ray table available, the tray under the table would provide more satisfactory results. However, if the x-ray table approach is selected, there is an additional consideration. In medical imaging, the tray under the table is employed when body parts are thicker than about 4 in. (10 cm). Since higher kV is required to penetrate the thicker body parts, more scatter radiation will be produced. In order to minimize the scatter reaching the film, a device termed a grid is built into the top of the tray mechanism. The grid is composed of parallel lead strips. In some x-ray tables, the grids will move back and forth in a transverse direction or reciprocate during the exposure. More commonly called

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C

A B

Figure 2.53A  George/Fred was placed on the x-ray table transversely. The long axis of the table is in the direction of the yardstick. The center ray of the x-ray beam would be directed to the center of the chest (A). For the first exposure, the center ray was shifted 2 in. (5 cm) to the right (B). A total 4 in. (10 cm) shift to the left (C) was the center for the second exposure.

A

B

Figure 2.53B  The resulting CR image of the first exposure processed on a Konica medical CR system. Note the relative position of the calcified hilar lymph nodes (A) and the radiopaque artifact (B).

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Figure 2.53C  Because the radiopaque object is more distant from the liver, there is a greater shift of the object on the second image. Since the relative position of the calcified nodes are closer to the spine, the shift in position is not as great.

a Bucky, after one of the individuals who developed the device, the motion of the device eliminates any shadow of the lead strips from appearing on the image and is more efficient at capturing the scatter radiation. In other tables, the grid is fixed in position above the tray, and close inspection of the resulting image will reveal the linear shadows of the lead strips. In either case, the central ray of the x-ray beam must be centered on the midlongitudinal axis of the x-ray table. Moving the central ray transversely across the table will result in a portion of the beam being absorbed by the grid; this is termed grid cut-off. Therefore, the second requirement, if the tray under the table is going to be employed, is that the shift must be along the center line of the table. The transverse x-ray tube shift technique was employed to get a perspective of the calcified hilar lymph nodes on a mummy known as George/Fred. In order to employ the transverse shift, the mummy had to be placed transversely across the x-ray table. In that position, his chest was over the center of the table and the Bucky tray beneath it (Figures 2.53A, 2.53B, and 2.53C). The second approach to stereoradiography is based on angular rather than a linear shift. Either the body or object can be rotated between 6° and 8° (Carlton and Adler 1992) or the

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Figure 2.54  The cobra coffin from the Rosicrucian Museum in San Jose, California.

x-ray source can be angled a total of 5°. The latter method was employed on a small Egyptian cobra coffin at the Rosicrucian Museum in San Jose, California (Mummy Menagerie 2003). The imaging challenge was to identify the contents of the small wooden coffin that had the approximate dimensions of 4 × 4 × 7 in. (10 × 10 × 18 cm). The coffin also had a snakelike carving mounted on its lid (Figure 2.54). The museum curator wanted to know what was in the coffin but did not want to risk opening the fragile artifact. A Polaroid image quickly demonstrated the skeletonized remains of at least one but possibly two snakes. Because the remains were on the bottom of the box, a lateral projection would only show superimposed skeletal elements. Since the remains were fragile, the box couldn’t be tilted for an oblique projection. Although an oblique view could have been obtained by keeping the coffin flat and angling the film and x-ray source, the edges of the box were so close that they would end up superimposed over the skeletal remains. A stereoradiograph could provide the information necessary. The coffin was built up on foam with a space to place the film behind it. On the first exposure, the x-ray tube was directed horizontally with the center of the x-ray beam directed to the center of the small box. The film was changed and the second exposure was taken with the x-ray tube angled 5°, but the central ray was still directed through the center of the coffin (Figure 2.55). When viewed stereoscopically, two snake skulls were noted, demonstrating the value of this stereoradiographic technique (Figure 2.56). Positioning Challenge: Going for the Long Shot  In field imaging, it is often the case that the “subject” cannot be moved. In addition, the x-ray tube and/or image receptor may not be able to be placed in an optimal position to collect the desired data. In these cases… go long! The approach is straightforward and follows the aforementioned direct square law: as the SID increases, the mAs, particularly the exposure time, must be increased. In order to determine the proper exposure values when using a “long shot,” an acceptable

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Figure 2.55  The setup for one of the two stereoradiographs of the cobra coffin.

exposure for a shorter distance can be inserted into the inverse-square formula (mAsnew = mAsold[Distanceold/Distancenew]2). While working in Lima, Peru, on the collection of mummy bundles from the site known as Purachuco, a lateral projection of the skull of a mummy was required (House of Bundles 2002). The mummy was in a supine position on an examination table. The head was turned to the right, but due to the fragile state of the remains, the mummy couldn’t be rotated. The only location to place the x-ray tube that matched the angle of the head was on the edge of a loft above the mummy (Figures 2.57A and 2.57B). Acceptable images of other areas of the body were obtained using 10 mAs at 48 in. or 4 ft (122 cm). The new SID was

Figure 2.56  Stereoradiographs of the cobra coffin.

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A

B

Figure 2.57A  The relative position of the x-ray tube (A) and the mummy (B) looking up at the

loft.

approximately 16 ft (488 cm). The following calculation was employed: (new distance/old distance)2; (16/4)2 (10 mAs) = (4)2 (10 mAs) = 16 (10 mAs) = 160 mAs. It is important to recall that the longer the exposure time, or when using multiple short exposures, the greater is the risk of overheating the x-ray tube. Cooling-off periods between multiple exposures must be employed and, when indicated, external cooling of the tube may be required. Therefore, four exposures, each at 40 mAs, were taken with a 30 s pause between exposures. The result was a usable lateral skull x-ray completing the data set for that mummy (Figure 2.58). Will Not Fit on the Film: Too Big  The largest-size medical x-ray cassette is 14 × 36 in. (35.6 × 91 cm), which could accommodate the entire spine on a single image for scoliosis studies. It would seem logical to take two separate standard 14 × 17 in. (35.6 × 43.2 cm) cassettes and then, once processed, simply put the images together. Unfortunately, it’s not that simple. Why? The answer has to do with a basic property of the x-ray beam: it diverges from the source. The only portion of the x-ray beam that is vertical is at the center of the cone of divergence. If two views were taken, let’s say of an entire leg, on the smaller cassettes the first would be centered over midfemur and second, over midtibia and fibula. The knees on the two processed images wouldn’t match up. Many instances arise in field research situations when the object is larger than the largest image receptor available. To avoid the issue of beam divergence and to acquire a single image of a large object can be problematic. This problem can be resolved by using multiple, slightly overlapped sheets of film to form a single, large image receptor. In addition, it should be noted that the SID must be sufficient to cover the entire film surface.

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A

B

Figure 2.57B  The relative position of the x-ray tube (A) and the mummy (B) looking down

from the loft.

Finally, using the direct square law, an exposure time can be calculated. If the desired results require a nonscreened image, along with the increased SID, additional increases in the exposure time will be necessary. Imaging the object in this manner, once processed, the individual images can be “stitched together” with commercially available photography processing programs such as Photoshop®, creating a seamless, single, complete image of the oversized object. Polaroid film worked well for this application. Since the Polaroid film was already in a light-tight flexible envelope, the film packets were easily fixed in place to a surface with masking tape in order to create a “single” large image receptor. An example demonstrating the use of multiple Polaroid film envelopes to produce a single image of a baboon mummy will be presented in Chapter 9. The procedure can be done with a number of cassettes; however, with multiple overlapping cassettes the metal edge of each cassette would be superimposed on the adjacent film, creating an artifact on the developed image. If instant film, such as Polaroid, is not available and if cassettes are to be used as the image receptors, the subject must be supported by a sheet of Plexiglas or some other radiolucent material. The support would permit cassettes to be put into place or removed, one after the other, from under the Plexiglas. In this way, the imaging can be conducted without moving the subject. A lateral radiograph of the Soap Lady mummy at the College of Physicians Mütter Museum in Philadelphia, Pennsylvania, will provide an example of “merging” multiple images. As part of a proposed new display, a complete AP and lateral radiograph of the entire mummy was needed. To acquire the lateral projection, a 14 × 36 in. (35.6 × 91 cm) was selected and a track was constructed (Figure  2.59) to support the cassette over the entire length of the mummy. In order to

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Figure 2.58  The nearly lateral radiograph of the mummy’s skull. Although the humerus (arrow) partially obscured the maxilla and mandible, it was possible to determine that the mummy was edentulous.

Figure 2.59  A lateral projection cassette support system was constructed with a 32 × 12 × 3/4 in. (81.2 × 30.5 × 1.9 cm) plywood base (A). A 36 in. (91.4 cm) long, 7/8 × 1/2 in. (2.2 × 1.29 cm) aluminum track (B) that held the cassette was mounted on a 28 in. (71 cm) long, 1½ × 1½ in. (3.8 × 3.8 cm) pine board (C). Once the support system was in place, counterweights, such as sand bags, were placed on the plywood to stabilize it.

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Figure 2.60  Without moving the x-ray tube, multiple lateral images of the Soap Lady were

taken, processed, scanned with a flatbed scanner with transparency adapter, and assembled to produce a single lateral image.

cover the entire mummy, the x-ray tube was placed at a 140 in. (356 cm) SID. A total of four exposures were taken, digitized on a flatbed scanner with a transparence adapter and “assembled” to create a single image (Figure 2.60). A nonscreen approach is by far the easiest and provides the greatest flexibility. A film support can be constructed using a sheet of Foamcore cut to the desired size. In the darkroom, conventional radiographic film is placed onto the support and held in place using thumbtacks. There should be at least 1/2 in. (1.25 cm) of overlap as each additional sheet of film is fixed to the surface of the support. Once the films are all in place, six layers of black gardening plastic or a single layer of black pool liner are used to make the “film holder” light tight. Duct tape should be used to secure the covering material. Using this nonscreened method, an image receptor of virtually any size can be constructed. We used this nonscreened Foamcore film holder approach on an articulated 84 in. (213 cm) skeleton also at the Mütter Museum in Philadelphia. The individual, who suffered from gigantism during life, was mounted in a cabinet with two other mounted skeletons. The giant’s skeleton could not be removed from the case for a radiographic study. There was insufficient space to get the required distance to cover a film holder over 90 in. (229 cm) tall (Figure 2.61). Therefore, two Foamcore support film holders were constructed. As previously described, the images were scanned in and “stitched” together (Figure 2.62). Among the imaging findings was a lack of organized trabecular pattern within the proximal femurs, suggesting the bones had not been subjected to weight-bearing stresses for several months prior to the individual’s death. Several factors should be taken into consideration before this procedure is undertaken. Since long distances are required between the image receptor and x-ray source, long exposure times will be needed. In addition, if film will be exposed directly without the amplifying effect of intensifying screens, the exposure times could require a total of minutes. Therefore, if many specimens are going to be imaged using this method, the high heat loading of the x-ray tube will reduce the tube “life.” Cannot Come out of the Cave: Redefining Portable  Whenever possible, radiography should be conducted in situ or as close to the recovery site as possible. This approach preserves the context and allows assessment of the mummified remains or artifacts to be made prior to moving or transport. Many field situations arise in which the subject cannot be moved due to its fragility or because of local cultural customs. In these situations, the term portable takes on greater meaning. In one example, we were to radiograph and conduct endoscopy on the mummified ancestral remains of the Ibaloi people that had been placed in caves deep in the Kabayan Jungle on the island of Luzon in the Philippines (Cave Mummies of the Philippines 2002). Local customs would only permit the remains to be moved around within a cave, and they could not be removed from the caves for study. The

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C

B

A

Figure 2.61  The setup employed to radiograph the Mütter Giant. The x-ray tube (A) was positioned to take an AP projection of the lower portion of the legs. The nonscreen black plastic film holder (B) was resting against the sheet of Foamcore (C).

challenge was to establish an imaging facility at the mouth of these remote caves. A gasoline generator was required to provide power for the radiographic and endoscopic instruments. The generator was strapped to a long pole and carried to the caves by two members of the Philippine Army who also served as a security team. The x-ray unit was a compact 1952 vintage U.S. Army field unit stripped down to its bare necessities and the image receptor was 8 × 10 in. (20.3 × 25.4 cm) Polaroid® Type 803 film. The “higher-speed” or “faster” Polaroid film was selected in order to reduce the exposure time by a factor of eight. The x-ray tube and image receptor support devices were fashioned with whatever was available in or around the cave. The tube was often balanced on rocks in the cave, with the film being supported by an ancient coffin or small stones (Figure 2.63). The images provided information related to the age at the time of death and remnants of soft tissue (Figure 2.64), substantiating the villager’s claims of embalming procedures. The quality of the radiographs demonstrated that imaging studies can be conducted in extreme settings. Cannot Get the Cassette under/behind Subject  Superimposition has been mentioned several times as a disadvantage of conventional radiography. The problem is compounded by mummified remains, whether they are in a flexed or extended position, due to the

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Figure 2.62  The assembled AP and lateral radiographs of the Mütter Giant. (Images courtesy of Andrew Nelson, PhD.)

immobile position of their extremities. Not only might an arm or a hand obscure a clear view of, for example the spine, but it may also make it difficult to make an assessment of the extremity itself. Since there may not be enough space for a cassette with intensifying screens to fit between the anatomical parts of interest, a flexible nonscreen film holder might provide a solution. An example of this flexible nonscreened film holder approach was demonstrated in the study of a sideshow mummy. Sideshow mummies were uniquely American phenomena. Unclaimed bodies, embalmed with either arsenic or formalin, were procured by entrepreneurs and incorporated into the traveling entertainment circuits that were popular in the late 19th and early 20th centuries. In order to attract paying costumers, sideshow promoters would create an incredible story surrounding the individual’s life and subsequent demise and our example, Hazel Farris, was no exception (An Unwanted Mummy 2001). Her legend stated that she was the wife of a man in Louisville, Kentucky. They both had a history of drinking and domestic disputes. One night, Hazel told her husband that she wanted to buy a hat, he said no, and so she shot him dead. Three sheriff’s deputies came to investigate, and she shot and killed all of them. The sheriff came in and entered into a scuffle with Hazel during which her ring finger was shot off. Hazel then bested the sheriff

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Figure 2.63  The setup employed to radiograph the Ibaloi mummy within the cave.

and shot him dead as well. Hazel fled back to her home in Bessemer, Alabama, where she became a “lady of the night.” Hazel confessed her crime to a lover, who decided to turn her in for a $500 reward that was placed on Hazel. Hazel didn’t want to go to jail, so she committed suicide by drinking arsenic in whiskey. Or so the story goes. The missing ring finger became important to the study to determine whether it was a pre- or perimortem event. Unfortunately, the hand was crossed over the body and, even with angled projections, an unobstructed view, free of superimposition, wasn’t possible (Figure 2.65A). However, there was sufficient space to slide a Polaroid film packet between the hand and the lower abdomen (Figure  2.65B). The result was an image of her hand free of superimposition and the finger in question appeared to have been amputated well before the time suggested by the story that brought people into the tent to view her remains (Figure 2.65C). In another field imaging case, there was inadequate space beneath or on the side of the mummy to accommodate a cassette. The mummy, known as Princess Anna, was at rest in Kastle, Germany (Princess Baby 2002). The legend states that Anna was the daughter of King Ludwig IV and died while in the Kastle region. The distraught king ordered that she be preserved for eternity. Friars mummified Anna, and she is currently interred in a wooden case at the church in Kastle. Due to her fragile state, the remains couldn’t be lifted high enough to permit the rigid cassette to be placed underneath the body. In addition, her left shoulder was so close to the side of the case that it precluded the use of a

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Figure 2.64  The excellent state of preservation is demonstrated by the presence of tracheal rings (arrows) seen on this lateral chest radiograph of an Ibaloi mummy.

Figure 2.65A  The Polaroid image of Hazel Farris’ hand superimposed over her abdomen, making it impossible to assess the condition of her fourth finger (arrow).

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Figure 2.65B  The Polaroid film packet (arrow) placed between the right hand and the

abdomen.

cassette for lateral projection. The nonscreen approach provided a solution for both problems. The flexible nature of the Polaroid film package allowed it to be smoothly positioned behind the mummy with minimal manipulation (Figure 2.66). The packet had sufficient stiffness to be slid between the shoulder and side of the case without curling onto the body (Figure 2.67). Summary of Unique Technical Challenges With the preceding presentation of the various technical challenges associated with field radiographic research, the authors hope that the reader will be better prepared to plan and execute conventional radiography in alternate settings. Although the list of challenges presented here may not be complete, it represents many of the major considerations and stresses that the preparation is a critical and integral part of field radiography.

Figure 2.65C  The nonscreen Polaroid image of the right hand, clearly demonstrating the remaining portion of the fourth proximal phalange (arrow).

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Figure 2.66  The AP of Princess Anna’s pelvis, showing Harris’ lines (arrows) on the iliac

crest.

Technical Advantages and Disadvantages of Conventional Radiography Technical Advantages The advantages of conventional radiography for field applications are numerous. Conven­ tional radiography provides the ability to “see” within objects such as mummy bundles, coffins, and wrapped artifacts. In addition, radiographs allow for the assessment of structures within structures. For example, not only can the radiograph provide an image of skeletal structures within a wrapped bundle, but it may also reveal a tumor within the bones. Radiography can be portable, making it possible to image skeletal and mummified remains and artifacts at or close to the recovery site. It is the optimal modality for initial

Figure 2.67  Lateral image of the mandible clearly visualizing unerupted teeth (arrows).

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examination in that it may minimize damage to potentially fragile remains with least disruption of taphonomy. The initial radiographs can be used to determine the necessity and objectives of advanced imaging procedures and may help direct conservation efforts. The radiographic unit is usually durable and reliable as long as it is packed well for travel and not used beyond its capabilities. Photographic paper using a Polaroid screened or nonscreened cassette provides maximum flexibility in getting the desired images with minimal waste and without the need for developing chemistry. Technical Disadvantages The major disadvantages of conventional radiography include the need for electric power, the superimposition of shadows, and the transportation of radiographic film. Without digital manipulation, conventional radiography produces a single image at a particular exposure setting. The “shades of gray” on the processed radiograph can’t be altered as compared to computerized radiographic modalities, in which density and contrast can be manipulated without having to repeat an exposure. Also, magnification and distortion of objects on the developed film preclude direct measurements off the images. Another major disadvantage of conventional radiography is the misuse of the technology by noncertified radiographers. In the United States, individuals must complete a minimum 24-month program to be eligible for a national certification examination. Even the entry-level radiographer would probably not have sufficient experience to formulate a plan for the establishment of a field radiographic facility. Their education is primarily based on producing acceptable radiographs of living patients with hydrated tissues. However, their knowledge base is sufficient to make adjustments in technical factors such as kVp and mAs. In addition, their ability to position patients can easily translate into manipulating mummified and skeletal remains to achieve the required projections. Individuals unfamiliar with the application of basic imaging principles, particularly for conventional radiography, will be less successful in producing diagnostic images of mummified and skeletal remains. Tremendous amounts of information will be missed or rendered useless because the images are either under- or overexposed. Even with correct exposure variables, there will be a loss of time and film, decreasing the efficiency of the imaging project. Probably of greater significance, improper application of conventional radiography by untrained individuals can result in catastrophic failure of the x-ray tube due to overheating. A damaged x-ray tube can also leak cooling oil onto specimens, causing irreparable damage. If the x-ray tube fails, particularly in a remote location, the radiographic phase of the study is over.

Complementary Data Acquisition Although the conventional radiograph provides critical information regarding contents of wrapped remains, the images are “shadows” with few descriptive characteristics. In the absence of advanced imaging, the complementary nature of endoscopic imaging cannot be understated. The endoscope, provided there is an entry route, can provide additional characteristics such as color, shape, and imaging of low-density objects or anatomical features. We have found that the field application of both modalities increases the obtainable data, adding to the interpretability of those data. The complementary nature of paleoimaging modalities will be demonstrated through the various case studies presented in this text.

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The information from conventional radiography will certainly contribute to the decisions regarding safe transportation of the remains or artifacts to a facility for advanced imaging methods. The conventional radiograph often provides information about the integrity of the remains and whether or not there are focused points of interest indicating the need for further imaging analysis.

Anthropological Applications: Laboratory and Field Objectives for Conventional Radiography The application of conventional radiography to anthropological research and data collection should be objective driven. That is, the formulation of a field imaging program should be designed to answer specific anthropological and archaeological questions. Often, radiography is conducted using a narrow scope of objectives, thereby limiting the data collected. It has been demonstrated that conventional radiography can make a wide variety of information available to researchers without having to disrupt the remains or artifacts. The following objectives are considered minimal and have proved to be obtainable through the application of conventional radiography. The objectives are divided into two broad categories: fundamental and refinement objectives. Fundamental objectives are those objectives that should be achievable in most cases. Refinement objectives are those objectives that have the potential to refine the data collection and add to the information derived. The refinement objectives may not be achieved but should be considered in every case. Fundamental Objectives Assess Condition of the Remains or Artifact Initially, conventional radiographs can help researchers determine the fragility and integrity of the remains or artifacts under investigation. The initial radiographs may help determine if a mummy or artifact is safe to move. The radiographic information collected to address this initial objective is best carried out at the exact location of the study subjects. The location may be a tomb, a cave, a remote research facility, or a museum. In each case, a radiographic examination reveals information that can be used to direct further study activities. These activities include those that can be conducted on-site and suggest studies using advanced imaging. The radiographs may also indicate the direction for possible conservation measures. One example is that of an on-site field examination of the mummies of Urbania, Italy, at the Church of the Brotherhood of the Good Death (Mama Mia Mummies 2003). These accidental mummies are on display behind the main portion of the church. The mummies were displayed in an upright position and were held in place by fragile wires. The initial conventional radiographs, conducted with the mummies in place, demonstrated that the remains were too fragile to be moved and severely limited future imaging research (Figure 2.68). Age at the Time of Death The next fundamental objective is to aid in the determination of the age at the time of death. The age at time of death can be determined by radiographically documenting the eruption pattern of the teeth, overall dental condition, overall bone and epiphyseal development, fusing patterns of skull bones, and degenerative changes. For individuals under

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Figure 2.68  The AP radiograph of the chest of a mummy (U18) from Urbania, Italy, showing the remains were held in place by wire. Since a number of the skeletal components appeared to be disarticulated, it was determined that the remains could not be moved.

approximately 25 years of age, the age assessment should be made using dental eruption patterns and an evaluation of as many epiphyses as can be visualized. Each of these data can then be compared to standardized anthropologic aging charts to assess age at the time of death. For individuals over the age of 25, data such as degenerative changes and dental wear need to be considered along with cultural characteristics such as the physical environment, diet, and work patterns of the culture being studied. The trabecular patterns within certain structures of long bones, such as the femoral neck and calcaneous, can also provide an estimation of age and can only be visualized radiographically. An example of determining age at the time of death can be found in the case of Princess Anna (previously described). In this case, the recorded age at the time of death of the young princess was three years. The lateral projection of the mandible demonstrated a tooth eruption pattern that suggested her age at the time of her death was more likely around 18 months. Additional radiographs of her wrists supported the earlier age at the time of death. In this case the historical record was corrected using the radiographic data. In population studies, determining the average age at the time of death can have greater meaning when the study size is large enough to conduct statistical analyses. Determination of Sex in Absence of Direct Observation Another fundamental objective is to determine the sex of the mummified individual. Conventional radiography can be very useful if the mummified remains are wrapped or

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Figure 2.69  An AP pelvis of a Chachapoya mummy demonstrating a subpubic angle, indicat-

ing a male.

within an enclosure. Key radiographs include an AP or PA and lateral projections of the pelvis and a lateral view of the skull. Although magnification on the radiographic image precludes direct linear measurements, the calculation of angles is unaffected. However, rotation of the body part would increase distortion and complicate the calculation. An AP or PA of the pelvis would reveal the subpubic angle. An angle of less than 90° suggests a male (Figure  2.69), and greater than 90° suggests a female (Figure  2.70). On a lateral projection of the pelvis, the greater sciatic notch is a fairly good indicator of the sex of the individual (Walker 2005) (Figures 2.71 and 2.72). The presence or absence of a browridge on a lateral view of the skull can also be used to indicate the sex of an individual. The presence of the browridge suggests a male (Figure 2.73), whereas the absence of the structure suggests a female (Figure 2.74). Additionally, the prominence of the occipital protuberance can help with sex determination (Figures 2.75 and 2.76).

Figure 2.70  The greater subpubic angle seen in the pelvic radiograph of this Chachapoya mummy, indicating a female individual.

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Figure 2.71  The narrow angle of the greater sciatic notch (arrow) demonstrated on the lateral projection of the pelvis of this Chachapoya mummy suggested a male.

Radiographic assessment of the long bones in terms of their robustness or gracile appearance can add data for interpretation related to this objective. In some cases where the differentiation is not obvious, artifacts associated with the remains and demonstrated on the radiographs may suggest the sex of the individual. For example, in the Chachapoya culture of north-central Peru, a pincer, used for pulling out whiskers, is frequently included within the mummy bundle of a male (Figure  2.77) and tupu and/or spindle-whorls are found in female bundles (Figure 2.78). Dentition The conventional radiograph can provide information regarding the dental status of mummified and skeletal remains. Features such as dental wear, caries, attrition, exposed roots, abscesses, bony lesions, and an assessment of peri- versus premortem tooth loss can all be demonstrated radiographically. It is important to note that due to the superimposition of shadows, specific projections are necessary to acquire images for dental assessment. Oblique views of each side of the maxilla and mandible are required to provide an unobstructed visualization of the canines, premolars, and molars (Figure 2.79). A PA projection with the incisors parallel to the image receptor plane will provide a clear view of the incisors (Figure 2.80).

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Figure 2.72  The wide angle of the greater sciatic notch (arrow) suggested a female Chachapoya

mummy.

Refinement Objectives Detection of Pathologies (Paleopathology) The human body, its organs and tissues, constantly interact with its external and internal environments throughout the individual’s life span. Many disease processes impacting the internal environment of the organism leave revealing signs in the afflicted organ or tissue. If the individual survives the acute phase and the disease persists, those signs, which are evidence of the disease, can eventually impact the bony structures, leaving a permanent record that can survive for millennia. Unfortunately, soft tissues begin to decompose rapidly after death, and some of the signs of disease can be lost to this process. In contrast, the skeletal system will endure where organs may not and provide evidence of disease or injury, which can be detected radiographically. Some examples of disease patterns that can be seen on conventional radiographs include the following: calcified lesions in the pulmonary tissue, traumatic injury to bony structures, an assessment of fractures as to their pre- or perimortem status, shifted mediastinal structures, renal and bladder stones, lesions within bones (Pott’s disease), gross morphologic variations in organs or bony structures, the impact of lesions on bony structures (sella turcica—pituitary lesions), and pelvic configuration as related to peripartum status. Morphological anomalies such as scoliotic

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Figure 2.73  The prominent browridge seen on the lateral skull radiograph suggested a male Chachapoya mummy.

Figure 2.74  The lack of a distinctive browridge suggested this individual was a female.

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Figure 2.75  A lateral Polaroid skull of a Guanajuato mummy (MH2) demonstrating the characteristic occipital protuberance (arrow) seen in males.

Figure 2.76  A composite lateral Polaroid skull and cervical spine of Marie O’Day without an

observable occipital protuberance. The radiopaque object within the mouth (arrow) is a vulcanite denture.

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Figure 2.77  The lateral skull radiographs of two Chachapoya mummies showing the pincers (arrows) included in the wrapping, suggesting a male.

conditions can also be detected via radiography. Biomechanical stress is well recorded in the bony structures, particularly at the location of articulations. Arthritic changes and changes in bony structures as the result of repetitive activity can be demonstrated by conventional radiography. Numerous paleopathological changes can be documented radiographically: a healed fracture of a humerus on a mummified Chinese immigrant (Figure  2.81) (Gallegos et al. 2002); a depressed skull fracture in the occipital bone, without healing, in an Egyptian mummy known as the Cook of Ra (Figure 2.82); what appears to be a compression fracture of a thoracic vertebrae in the lateral chest radiograph of this Chachapoya mummy (Figure 2.83) (Bravo et al. 2001); two radiographic examples of bladder stones (Figures 2.84A and 2.84B) (Bravo et al. 2003); avascular necrosis of the hip (Figure 2.85); and calcifications of arteries within the pelvis (Figure 2.86). It is important to note that although a disease, particularly

Figure 2.78  A pair of tupus seen in the AP and lateral radiographs of this Chachapoya mummy, indicating the individual was a female.

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Figure 2.79  An oblique projection of the left mandible of a Guanajuato mummy, MM10.

one within the remaining soft tissues, may be detected by radiograph, the specific disease can only be determined by a paleopathologist. Target Identification for Biopsy and Retrieval In many cases, radiography reveals an area of interest that warrants closer study. Typically, this is a particular pathological anomaly or an artifact either within the mummy or among the mummy wrappings. If it is within the research protocols and the target is to be biopsied or removed, conventional radiography can be employed to pinpoint the spatial relationship

Figure 2.80  A PA projection on a Guanajuato mummy, MH2.

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Figure 2.81  A chest radiograph of a Chinese mummy recovered from northern Nevada. Note the old fracture of the humerus (arrow).

of that target. Clearly, the imaging modality of choice for this task is computed tomography, CT. However, in the field conventional radiography can be successfully employed to pinpoint lesions and artifacts. The object may be located by using two long needles, such as spinal needles, inserted at right angles into the approximate target location. Taking into account inherent characteristics such as magnification and distortion, the depth and direction of needle insertion are determined from the original radiographs. Radiographs taken at right angles to the needles while in place will provide an assessment of the target’s spatial relationship relative to the needles. The target, once located, can then be biopsied or extracted under endoscopic guidance.

Figure 2.82  A lateral skull of a mummy known as the Cook of Ra that was radiographed at Yale University’s Peabody Museum. Note the fracture (arrow) of the occipital bone.

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Figure 2.83  A compression fracture of a thoracic vertebrae (arrow) demonstrated on the lateral chest radiograph of a Chachapoya mummy.

Two examples using conventional radiography with needle localization are provided. In the first case, a radiopaque mass, thought to be a kidney stone, was demonstrated on the abdominal radiograph of a mummy located in a crypt under a church in Popoli, Italy (Tales of an Italian Crypt 2001). In order to remove the mass endoscopically,

Figure 2.84A  An AP pelvis image of a mummy (U6) from Urbania, Italy, with an apparent extremely large bladder stone.

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Figure 2.84B  A small bladder stone noted within the pelvis of another mummy (U18) from Urbania, Italy.

spinal needles were inserted at right angles in the suspected region to serve as a guide (Figure 2.87A). Periodically, while the endoscope was advanced, radiographs were taken to document the precise location of the device until the mass was removed (Figure 2.87B). Subsequent analysis of the mass verified it was a kidney stone (Fornaciari et al. 2002). This field application for spatial location reduces the need to move the study subject to an imaging facility, thereby reducing the risk any dislocation of the target within the internal context.

Figure 2.85  Another mummy (U5) from Urbania, Italy, with an apparent congenital dislocation of the right hip. The poor condition of the mummy was readily identified by the loose ribs in the pelvis.

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Figure 2.86  Bilateral calcified arteries (arrows) were noted within the pelvis of a mummy from Urbania, Italy.

The second case involved a sideshow mummy known as Hazel Farris. Polaroid radiographs demonstrated a radiopaque mass in the chest (Figure 2.88A). A CT examination confirmed the presence of the mass but clearly indicated that it was located within the major vessels of the heart (Figure 2.88B). Because the “owner” of the mummy had scheduled the mummy to be cremated following the examination, an autopsy was permitted. At autopsy, the heart and lungs were removed. In an attempt to correlate the location of the mass seen on the conventional radiography and the CT image, pins were placed at right angles to each other and the specimen was radiographed (Figure 2.88C) (Cartmell et al. 2002). The resulting image confirmed the location of the mass previously noted and after removal it was determined to be a hardened blood clot. Similar radiopaque masses had been noted within the vessels associated with the heart of other sideshow mummies that had been embalmed with arsenic. It was concluded that the dense clots were associated with the embalming procedure. In a recent study (Beckett et al. 2008), we evaluated another possible field technique for specific target needle biopsy using standard radiography, endoscopic guidance, and tissue target triangulation using a radiopaque “locator grid” technique.

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Figure 2.87A  A Polaroid radiograph of the left medabdominal region of the mummy from Popoli, Italy, with the two spinal needles (arrows) placed at right angles in order to locate the kidney stone.

Context in bioanthropology refers to the place where mummified remains are found as well as the surrounding environment, associated grave goods, and the relationships among these many variables. Typically, context refers to the external environment and the relationship of the mummified remains to those surroundings. Internal context refers to

Figure 2.87B  The renal stone after it was extracted from the mummy.

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Figure 2.88A  A Polaroid AP radiograph of the chest of Hazel Farris, demonstrating a radiopaque mass (arrow) located to the left of the midline.

those anatomical structures or artifacts within the mummy itself. Contextual information is critical when attempting to interpret anthropological, archaeological, and paleopathological data (Buikstra and Beck 2006). The more information and data recorded in situ, the better able those data may inform researchers about the person and how his or her biology interacted with the environment. If the internal context is disturbed, relationships between morphological features may be disrupted, which in turn may lead to misinterpretations regarding the mummified remains. In an attempt to preserve both the external

Figure 2.88B  An axial CT image demonstrating the radiopaque mass (arrow) in the heart.

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Figure 2.88C  A radiograph of the heart and lungs after they were removed from the body. Pins were place vertically and horizontally (arrows) in order to localize the radiopaque mass.

and internal context associated with mummified remains, scientific study, including tissue biopsy, should be conducted in situ. The goal of this study was to explore a possible field technique for needle biopsy in an attempt to preserve context. The study was conducted under endoscopic guidance to ensure tissue target location and penetration of the biopsy needle. The subject of this study was a late 19th to early 20th century mummified male. The subject was a sideshow mummy known as George/Fred, curated by Ripley’s Believe it or Not, which was subsequently donated to the Bioanthropology Research Institute for research and educational purposes (Figure 2.89). The mummy is that of a male whose external and internal preservation are very good, making the subject an excellent choice for organ tissue biopsy. The state of preservation of the subject’s internal organs was excellent, with cardiac, pulmonary, and hepatic organs intact. For this study, the liver was targeted for biopsy as its radiographic density indicated that the hepatic tissue was easily recognizable and accessible for biopsy.

Figure 2.89  A photograph of the mummy George/Fred.

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Figure 2.90  Locator grids positioned on George/Fred.

In field settings, using CT instrumentation to allow for guided biopsy is not practical due to size and availability. Using conventional radiography, AP and lateral radiographs were taken of the area of interest to estimate the organ target location, in this case, the liver. Two “locator grids” were constructed using standard garden fencing with 0.5 × 0.5 in. (1.25 × 1.25 cm) “windows,” which were attached to frames large enough to hold a standard 14 × 17 in. (35.5 × 43 cm) x-ray cassette. The two locator grids were constructed to produce a right angle to one another directly over and next to the subject, ensuring that the image produced would encompass the target organ region as determined by the initial set of x-rays (Figure 2.90). The grid was constructed so that the horizontal level could be adjusted. A small metallic marker was placed on each grid at the approximate location of the target organ and in the same axial plane. X-ray cassettes were placed for the AP and lateral views in a manner such that the grid and metallic markers would appear on the developed films. Using the locator grid markers as a guide, the depth and the lateral location of the target organ were determined by counting the locator grid squares in relationship to the locator grid markers (Figure 2.91). A bone marrow biopsy aspiration needle was used to create the percutaneous route to the target organ identified by the grid markers. Once the route was

Figure 2.91  Radiograph showing locator grid markers used to locate target organ.

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Figure 2.92  Coaxial needle in place using locator grid as a guide.

established, a coaxial percutaneous biopsy needle was placed at the depth and lateral position established using the grid markers (Figure 2.92). Radiographs were repeated to ensure biopsy needle location in relation to the target organ. The AP and lateral radiographs (Figures 2.93 and 2.94) demonstrate that the location of the target organ using marked locator grids for triangulation was readily accomplished. The drawing in Figure 2.95 demonstrates the triangulation and target location method in the axial plane. The use of the locator grid system with standard radiography appears to hold promise in the target organ identification and subsequent biopsy in field settings. Key features of the locator grid include making sure the system is adjustable to accommodate varied morphologic configurations and stabilization of the system to ensure that right angles are easily produced and maintained. The triangulation method using the locator grid with standard radiography may prove to be a useful field approach to precise tissue- or organ-targeted biopsies. The ability to conduct such biopsies in the field helps preserve the context and eliminates the risks associated with transporting those remains to an advanced imaging facility. Continued research needs to be conducted using smaller targets to assess the precision of this field technique. Cultural Practices Ancient Medical Practices  Ancient cultures appear to be fairly sophisticated in their medical practices. In the case of the Inca and other populations as well, trephinations were performed with great skill and with a remarkable success rate. It has been determined that among the Inca, based on new bone growth at the procedure site, trephination survival approached an 80% success rate (Verano 2003). Conventional radiography can be used to demonstrate not only the frequency of the medical practice of trephination but also the degree of success as determined by new bone growth at the site (Figure 2.96).

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Figure 2.93  AP radiograph showing coaxial needle in place at target organ.

Cultural Cranial Modification  What follows is a description of the practice of cultural cranial modification and the contribution made by conventional radiography not only to the recognition of its presence but also to the recognition of the biological impact of the modification practice. Background  Cultural cranial modification (CCM) can be defined as the intentional manipulation of the developing crania of infants to reshape the skull. CCM is accomplished through various cranial binding methods, which range in duration from weeks to years. The biological change that results from CCM procedures remains fixed over the life course of the individual. CCM has been practiced by many cultures throughout the world. CCM Variations Annular reshaping. It is the result of circumferential binding of the crania. This binding creates a decrease in cranial breadth and an increase in cranial length (Figure  2.97). Within this classification are three common variations: conical, tubular, and elongated.

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Figure 2.94  Lateral radiograph showing coaxial needle in place at target organ.

Figure 2.95  Triangulation and target location shown in a CT axial plane.

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Figure 2.96  Healing trephination clearly seen in the skull on the right.

Tabular reshaping. It is the result of an AP compression of the crania. Tabular reshaping results in an increase in cranial breadth, which is in contrast to the annular variation (Figure 2.98). The Impact of CCM  Biological effects: A wide variety of biological effects of CCM have been reported. There appears to be a relationship between CCM and a change in wormian bone frequency (Koningsberg et al. 1993; O’Laughlin 2004). Variations in suture

Figure 2.97  Radiograph of annular cultural cranial modification (CCM).

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Figure 2.98  Photograph of tabular cultural cranial modification.

configuration and complexity have also been reported (Gottlieb 1978; Blom 1999). Additionally there appears to be a correlation with the development of porotic hyperostosis (White 1996). Pressure necrosis in the occipital region has also been reported (Dietz and Bergfield 2001). There have been conflicting reports regarding the impact of CCM on vascular changes. One study using virtual endocasts made from CT scans of modified Mayan skulls demonstrated minimal effect on blood vessel foramina (MacLellan 2006). Another study reports a redirection of sinuses and meningeal vessel paths as they adapt to the new cranial vault shape (O’Laughlin 1996). Pathological effects: CCM has also been associated with craniosynostosis (White 1996). Craniosynostosis is a premature fusion of one or more of the cranial sutures. A single suture fusion is referred to as a simple craniosynostosis. Compound craniosynostosis involves two or more sutures. The cranial bones are well developed by the fifth gestational month in normal fetal development. After birth, the anterior fontanel closes around the age of 20 months. The posterior fontanel normally closes around 3 months. Mature suture closure is seen at about 12 years of age, with complete suture fusion occurring in the third decade and beyond. Craniosynostosis has many clinical implications for the afflicted individual. If it is simple craniosynostosis, the impact is largely cosmetic in nature. Compound craniosynostosis, on the other hand, presents with more grave clinical implications. Compound craniosynostosis carries an increased risk of elevated intracranial pressure when associated with bilateral coronal suture involvement. Further, it may also lead to anomalies of venous drainage. Compound craniosynostosis may also lead to a hypoplastic maxilla, resulting in upper airway problems and shallow orbits resulting in ophthalmologic conditions. Diagnosis of craniosynostosis includes radiography using AP or PA, a lateral, and, if possible, a Towne’s projection. In normal cranial flat bone development, radiographically the sutures appear as serrated, nonlinear lines, while with craniosynostosis suture markings appear as linear or are absent with early fontanel closure. Additionally, a skull radiograph

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Figure 2.99  Extensive annular cultural cranial modification in this child mummy in Cuzco,

Peru.

showing a beaten copper appearance associated with craniosynostosis indicates an increase in intracranial pressure, which may lead to other issues of vascular status and integrity. Two Subadult Case Studies of CCM Impact  Here are two case studies that demonstrate the utility of conventional field radiography in the detection of the biological impact of cultural practices such as CCM (Guillen et al. 2007). Case #1. The first case is that of an infant mummy under two years of age, likely Incan in origin, in Cuzco, Peru. The mummy presented with obvious annular CCM, demonstrated by major elongation of the skull (Figure 2.99). Lateral radiograph revealed fused coronal sutures (Figure  2.100). To further document suture fusion patterns, a modified Towne’s projection was obtained (Figure 2.101). The resulting radiograph demonstrates the

Figure 2.100  Lateral radiograph. Note fused coronal sutures.

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Figure 2.101  Direction of x-ray for a modified Towne’s projection.

fused sagittal suture patterns as well as the completely closed fontanels (Figure 2.102). The fused linear suture patterns and the closed fontanels demonstrate craniosynostosis in this infant mummy exhibiting annular CCM. There are a variety of clinical disorders associated with premature suture fusion. They include hypothyroidism, hypophosphatemia, hypercalcemia, vitamin D deficiency, severe constriction in utero, and positional molding (a type of cranial modification).

Figure 2.102  Radiograph from the modified Towne’s projection showing a fused sagittal suture and closed fontanels.

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Figure 2.103  Wrapped Chiribaya child mummy bundle.

The fused linear suture patterns and the closed fontanels demonstrate craniosynostosis in this less than 2-year-old infant mummy exhibiting annular CCM. It is beyond the scope of the study conducted to rule out the varied differential diagnoses. Although we cannot reliably determine the cause of death, it is reasonable to assume that the CCM, along with the craniosynostosis and its associated clinical disorders, may have contributed to this child’s morbidity or mortality. Case #2. The second case presentation is that of a wrapped infant mummy of the Chiribaya culture at the Centro Mallqui research facility, El Algarrobal, Osmore River Valley, near Ilo, Peru (Figure 2.103). A radiograph taken of the mummy bundle demonstrates an infant with annular CCM (Figure 2.104). An endoscopic route of entry was found on the posterior surface of the mummy bundle near the base of the skull. The endoscope was introduced and manipulated into the cranial vault. The endoscopic image revealed a mottled endocranial surface in the location of the cranial venous sinuses, which was deep reddish brown in color (Figure 2.105). The mottled endocranial surface suggests an increased intracranial pressure may have been present. The presence of residual darkened substance associated with the mottled surface suggests possible clotted, dried blood. This is suggestive of premortem intracranial hematoma. There are a variety of clinical disorders associated with increased intracranial pressures. They include generalized brain swelling, which in turn may lead to acute hepatic failure, ischemia, pseudotumor development, hypersensitivity encephalopathy, hypercarbia, Reye’s hepatocerebral syndrome, and decreased cerebral perfusion pressure. Also associated with increased intracranial pressure is increased venous pressure leading to possible venous thrombosis and obstruction of superior mediastinal or jugular veins. Obstruction to cerebral spinal fluid flow with or without absorption may lead to hydrocephalus, extensive meningeal disease, and obstruction of cerebral complex or superior sagittal sinus flow. Of particular interest is what is called the mass effect associated with increased intracranial pressure. This mass effect may lead to cerebral infarct with edema, subdural or epidural hematoma, and abscess or tumor formation.

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Figure 2.104  Radiograph showing extensive annular cranial modification.

The clinical picture of an individual afflicted with increased intracranial pressure includes headache, nausea, vomiting, papillary edema, papillary dilation, and poor sensorium. Given the radiographic and endoscopic data, this subadult (