Preface
Purpose and Content
The purpose of Radiologic Science for Technologists: Physics, Biology, and Protection is threefold: to convey a working knowledge of radiologic physics, to prepare radiography students for the certification examination by the ARRT, and to provide a base of knowledge from which practicing radiographers can make informed decisions about technical factors, diagnostic image quality, and radiation management for both patients and personnel.
This textbook provides a solid presentation of radiologic science, including the fundamentals of radiologic physics, diagnostic imaging, radiobiology, and radiation management. Special topics include mammography, fluoroscopy, interventional radiology, multislice helical computed tomography, and the various modes of digital imaging.
The fundamentals of radiologic science cannot be removed from mathematics, but this textbook does not assume a mathematics background for the readers. The few mathematical equations presented are always followed by sample problems with direct clinical application. As a further aid to learning, all mathematical formulas are highlighted with their own icon.
Likewise, the most important ideas under discussion are presented with their own colorful penguin icon and box:
The tenth edition improves this popular feature of information bullets by including even more key concepts and definitions in each chapter. This textbook also presents learning objectives, chapter overviews, and chapter summaries that encourage students and make the text user-friendly for all. Challenge Questions at the end of each chapter include definition exercises, short-answer questions, and a few calculations. These questions can be used for homework assignments, review sessions, or self-directed testing and practice. Answers to all questions are provided on the Evolve site at http://evolve.elsevier.com.
Historical Perspective
For seven decades after Roentgen’s discovery of x-rays in 1895, diagnostic radiology remained a relatively stable field of study and practice. Truly great changes during that time can be counted on one hand: the Crookes tube, the radiographic grid, radiographic intensifying screens, and image intensification.
Since the publication of the first edition of this textbook in 1975, however, newer systems for diagnostic imaging have come into routine use: multislice helical computed tomography, computed radiography, digital radiography, and digital fluoroscopy. Truly spectacular advances in computer technology and x-ray tube and image receptor design have made these innovations possible, and they continue to transform diagnostic imaging.
New to This Edition
Currently we are accelerating to all-digital imaging. Digital radiography is replacing screen-film radiography rapidly and this requires that radiologic technologists acquire a new and different fund of knowledge in addition to what has been required previously—and in the same length of training time! The chapters of the book have been reorganized, consolidated, and updated to reflect the current imaging environment.
Ancillaries
This resource has been updated to reflect the changes in the text and the rapid advancements in the field of radiologic science. Part I offers a complete selection of worksheets organized by textbook chapter. Part II, the Math Tutor, provides an outstanding refresher for any student. The Laboratory Experiments, formerly in the workbook, collect experiments designed to demonstrate important concepts in radiologic science. These are now available on the Evolve site at http://evolve.elsevier.com for ease of use.
Evolve Resources
Instructor ancillaries, including an ExamView Test Bank of over 900 questions, an image collection of all of the images in the text, and a PowerPoint lecture presentation are all available at http://evolve.elsevier.com.
A Note on the Text
Although the ARRT has not formally adopted the International System of Units (SI units), they are presented in this tenth edition. With this system come the corresponding units of radiation and radioactivity.
The roentgen and the rad are being replaced by the gray (Gya and Gyt respectively) and the rem by the sievert (Sv). In this edition, the SI units are presented first, followed by the earlier units in parentheses. A summary of special quantities and units in radiologic science can be found on the inside front cover of the text.
Radiation exposure is measured in SI units of C/kg, measured in mGy. Because mGy is also a unit of dose, a measurement of radiation exposure is distinguished from tissue dose by applying a subscript a or t to mGy, according to the recommendations of Archer and Wagner (Minimizing Risk From Fluoroscopic X-rays, PRM, 2007). Therefore, radiation exposure is measured in mGya and tissue dose in mGyt.
Acknowledgments
For the preparation of the tenth edition, I am indebted to the many readers of the ninth edition who submitted suggestions, criticisms, corrections, and compliments.
I am particularly indebted to the following radiologic science educators, whom I have identified on the Dedication page of this tenth edition. Their suggestions for change and clarification were always right on target. Many supplied illustrations, and they are additionally acknowledged with the illustration.
My friend and colleague, Ben Archer, is the author of the Penguin Tale (Page 3), which for me has become a particularly effective teaching tool. And that, in turn, has led to some thirty Penguintoons suggested by educators and students, which I now show regularly during lectures. I’ll never forget the first. Three of Ruby Montgomery’s students interrupted me at Judy William’s Atlanta SRT Student and Educators’ Conference in 2002. “Do polar bears eat penguins?” they asked. “Sure they do, they’re carnivorous,” I responded. “No, polar bears live at the North Pole, penguins at the South Pole!” … intense audience laughter.
The drawing of the Penguintoons and the illustrations in this book are the work of another close friend and colleague, Kraig Emmert. Thanks Kraig for your exceptional time and effort.
When I am in the audience of a lecture and leave with a single Penguin, I consider the lecture successful. I received a significant Penguin that is reflected in this tenth edition while riding the shuttle bus at the 2008 RSNA. I’m sitting next to a medical physicist who pointed out what a dummy I was for misusing the term spiral. I would like to acknowledge him in Figure 28-10, but I cannot remember who he was!
As you, student or educator, use this text and have questions or comments, I hope you will email me at sbushong@bcm.edu so that together we can strive to make this very difficult material easier to learn. I may not respond immediately, but I promise I will respond.
“Physics is fun” is the motto of my radiologic science courses.