1st Edition

The Physics of CT Dosimetry
CTDI and Beyond

ISBN 9780367780043
Published March 31, 2021 by CRC Press
232 Pages

USD $54.95

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Book Description

This book explores the physics of CT dosimetry and provides practical guidance on best practice for medical researchers and practitioners. A rigorous description of the basic physics of CT dosimetry is presented and illustrates flaws of the current methodology.

It also contains helpful (and rigorous) shortcuts to reduce the measurement workload for medical physicists. The mathematical rigor is accompanied by easily-understood physical explanations and numerous illustrative figures.


  • Authored by a recognised expert in the field and award-winning teacher

  • Includes derivations for tube current modulation and variable pitch as well as stationary table techniques

  • Explores abnormalities present in dose-tracking software based on CTDI and presents methods to correct them

Table of Contents

Chapter 1: Introduction and History. Chapter 2: Derivation of Dose Equations for Shift-Invariant Techniques and the Physical Interpretation of the CTDI-Paradigm. Chapter 3: Experimental Validation of a Versatile System of CT Dosimetry Using a Conventional Small Ion Chamber. Chapter 4: An Improved Analytical Primary Beam Model for CT Dose Simulation. Chapter 5: Cone beam CT Dosimetry: A Unified and Self-Consistent Approach Including All Scan Modalities – With or Without Phantom Motion. Chapter 6: Analytical Equations for CT Dose Profiles Derived Using a Scatter Kernel of Monte Carlo Parentage Having Broad Applicability to CT Dosimetry Problems. Chapter 7: Dose Equations for Tube Current Modulation in CT Scanning and the Interpretation of the Associated CTDIvol. Chapter 8: Dose Equations for Shift-Variant CT Acquisition Modes Using Variable Pitch, Tube Current, and Aperture, and the Meaning of their Associated CTDIvol. Chapter 9: Stationary Table CT Dosimetry and Anomalous Scanner-Reported Values of CTDIvol. Chapter 10: Future Directions of CT Dosimetry and A Book Summary.

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Robert L. Dixon, Ph.D, FACR, FAAPM is Professor Emeritus in the Department of Radiology, Wake Forest University School of Medicine, USA and holds a Ph.D. in Nuclear Physics.

He has taught physics and medical physics for decades, and is a recipient of the Radiology Department’s Teaching Excellence Award. He is also a past president of the American Association of Physicists in Medicine (AAPM) as well as past Chairman of the AAPM Science Council and CT Committee; and is a past Vice President of RSNA. He has published many papers on CT dosimetry in the journal Medical Physics and is a five-time winner of the SEAAPM Best Publication Award.

Prof. Dixon is a member of the IEC MT30 CT committee; is a designated US CT Expert (ANSI); and has been an invited keynote speaker at multiple International Conferences. He has also been a member of the Governing Board and the Executive Committee of the American Institute of Physics (AIP), and has received the Distinguished Service Award and the Lifetime Achievement Award of the American Board of Radiology (ABR).

He was also an airshow performer (1991-2006) flying former military aircraft including an ex- Soviet Air Force jet.


"This textbook is a great resource for medical physicists involved in CT dosimetry, even for those who have followed the publications of Dr. Dixon over the years, since it offers a comprehensive discussion, as well as important pitfalls in present-day CT dosimetry. The author is very direct in his criticism of the CTDI-formalism and eloquent points aremade on why a new formalism is needed. However, the take-away message from this textbook is not the criticism, but rather the rigour of mathematics and physics in the derivation and application of the convolution method, which can be used to further the understanding of CT dosimetry."
—Prof Jonas Andersson in Physica Medica (69, 2020, 126)

"This book is written by Professor Robert L Dixon who is very famous in the diagnostic radiology, especially for computed tomography (CT) dosimetry work. This book addresses the needs of all medical physicists who are working on the optimization of CT dose. I am confident that who so ever will refer to this book will appreciate its content. Diagnostic radiology is an integral part of any hospital. CT imparts the largest portion of radiation dose among all radiation diagnostic imaging equipment. As the number of examinations is going up every year, ‘As Low As Reasonably Achievable’ (ALARA) principle has become a central issue for any radiation installation with the intention to bring the doses down. Understanding the concept of CT dose index (CTDI) is a very important topic to optimize the patient doses.
Overall, this book is valuable. I certainly recommend this book to all physicists, teachers, and students who want to get involved in CT dose optimization."
—Prof Gurpreet Singh, Journal of Medical Physics, 2019