Diagnostic Medical Imaging in Pediatric Patients and Subsequent Cancer Risk

David J.Mulvihill, MD; Sachin Jhawar, MD; John B.Kostis, MD; SharadGoyal, MD

Introduction
Environmental factors have long been thought to play a role in the development of adult and pediatric malignancies. Studies involving long-term survivors of the atomic bombing of Hiroshima and Nagasaki as well as studies involving nuclear and radiation workers have provided compelling evidence correlating ionizing radiation with carcinogenesis 1, 2. Furthermore, it is estimated that only 5% of pediatric cancers are directly attributable to an inherited genetic cause (3), and ionizing radiation has been shown to be causal in a large number of human malignancies (4). At times veiled within the context of health-care delivery, exposure to ionizing radiation from diagnostic medical imaging is increasing in the United States. In a report by the National Council on Radiation Protection and Measurements in 2009, it was stated that “in 2006 Americans were exposed to more than seven times as much ionizing radiation from medical procedures as was the case in the early 1980s” (5). The pediatric population is certainly not immune to the rising radiation exposure from medical imaging. For example, the increased use of computed tomography (CT) scanners in the diagnosis of pediatric conditions has grown steadily over the past decade (6), and according to some publications, the use of this diagnostic modality may be substantially higher in the United States than in other parts of the world (7). Recognizing that 40% of medical radiation exposure in the United States is a result of cardiovascular imaging and intervention, the American Heart Association has recently published a scientific statement that outlines practical approaches to improving radiation safety during cardiovascular imaging and interventional procedures (8). This statement includes recommendations based on the benefit of proposed procedure or treatment in conjunction with strength of scientific evidence of efficacy and concludes with an outline of core concepts of improving radiation safety in medical imaging that include education, justification, and optimization.

One of the most challenging aspects involving cancer risk assessment resulting from diagnostic imaging is the quantitation and standardization of radiation exposure and dose (8). Radiation dose to a patient varies considerably with the imaging modality being employed. At the lower end of the spectrum, a simple Posterior-Anterior (PA) chest radiograph may result in an effective dose of 0.013 mSv per study, whereas a CT scan of the abdomen or pelvis would result in an effective dose of 15 mSv per examination (2). Furthermore, in procedures such as catheterizations performed under fluoroscopy that require operator skill and are influenced heavily by patient characteristics, there can be tremendous variability in radiation dose 9, 10. The earliest population-based studies examining cancer risk after exposure to ionizing radiation from diagnostic medical imaging used a number of procedures [more…]