Cancer Risks Following Medical Imaging: The Scare, The Science, and The Path to Resolution

Date(s) - 09/30/2019
3:00 pm - 4:00 pm

Communicore, C1-17

Wesley Bolch, Ph.D., Professor, J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida

Radiation imaging of the patient in the form of radiography, fluoroscopy, nuclear medicine, and computed tomography (CT) is an integral and essential component of patient care.   Image formation by x-rays and gamma-rays necessarily delivers a radiation dose to tissues within the imaging field – energy imparted per mass of tissue – that, in current radiological protection theory, results in a risk of cancer induction proportional to the dose level (the Linear No-Threshold or LNT theory).  The benefits of medical imaging are substantial, and thus an optimization of benefit and risk must be applied to imaging systems and to individual patients.   In this presentation, we will start with a review of the “scare” – journal and news articles which heralded the degree of cancer induction by medical imaging – particularly in regard to CT imaging of children.  These risk estimates were derived from fairly crude estimates of organ dose and cancer risk models developed from radiation epidemiology studies.  The most pivotal study from which these risk models are developed were those of the atomic bomb survivors at Hiroshima and Nagasaki.  We’ll next review the response to this scare by the medical imaging community, the response by the imaging system manufacturers, and discuss the “science” of cancer risk projection in contrast to cancer risk assessment.  We’ll conclude with “the path to resolution” – new radiation epidemiological studies of medical exposed individuals.   In particular, we’ll discuss how UF is playing a significant role in the patient organ dosimetry of the nation’s very first radiation epidemiological study of medically imaged children.  It is anticipated that, upon the conclusion of this study, the “true” magnitude of cancer risks in medical imaging will be quantified.


Dr. Wesley E. Bolch is Professor of Biomedical Engineering and Medical Physics in the J. Crayton Pruitt Family Department of Biomedical Engineering at the University of Florida (UF).  He serves as Director of ALRADS – the Advanced Laboratory for Radiation Dosimetry Studies at UF.  Dr. Bolch earned his BSE degree in environmental engineering in 1984, his ME and PhD degrees in radiological physics in 1986 and 1998, respectively, from the University of Florida.  He has been certified by the American Board of Health Physics since 1994 and licensed in Radiological Health Engineering by the Texas Board of Professional Engineers since 1992.  In 2011, Dr. Bolch was elected Fellow of both the Health Physics Society (HPS) and the American Association of Physicists in Medicine (AAPM).  He has been a member of the Society of Nuclear Medicine’s Medical Internal Radiation Dose (MIRD) Committee since 1993, a member of the National Council on Radiation Protection and Measurements (NCRP) since 2005, and a member of Committee 2 of the International Commission on Radiological Protection (ICRP) since 2005.  Within the latter, he serves as C2 Secretary and Leader of the ICRP Task Group on Computational Phantoms and Radiation Transport (CPRT).  He has published over 230 peer-reviewed journal articles, co-authored/edited 18 books/book chapters, and served as author on three NCRP Reports, nine ICRP Publications, one ICRU Report, and three MIRD Monographs. Dr. Bolch has managed a broad research program including (1) NIH and DOE funded projects to construct high-resolution models of the skeleton to support dose-response studies in radionuclide therapy and radiation epidemiology, (2) NIH funded projects to develop scalable NURBS-based and voxel-based computational phantoms of adult and pediatric patients and associated software for organ dose assessment in nuclear medicine, computed tomography, interventional fluoroscopy, and radiotherapy, (3) private company funded projects to develop stereotactic kilovoltage x-ray treatments for age-related macular degeneration and glaucoma, and (4) CDC funded projects in stochastic modeling of worker inhalation and gamma-ray exposures following radiological accidents and potential terrorist events.  He is the recipient of the 2014 Distinguish Scientific Achievement Award by the Health Physics Society acknowledging outstanding contributions to the science and technology of radiation safety.