Medical Radiation Effects Discussed At TCT Meeting.


CCTA_image_1According to a recent presentation, 15% of radiation exposure in the United States takes place during cardiac imaging procedures, especially during coronary CT angiography (CCTA). The presentation was highlighted during the 2010 annual Transcatheter Cardiovascular Therapeutics (TCT) meeting, which was held recently. Andrew J. Einstein, MD, from Columbia University Medical Center, New York, said "We don't want to overlook the fact that the biggest clinical significance of radiation exposure is the benefits. Ultimately, this exposure to ionizing radiation can improve patient and societal outcomes."

He noted that the effects of radiation exposure are divided into two types, deterministic or stochastic. He explained that deterministic effects include killing cells by radiation, such as radiation sickness and skin burns. On the other hand, stochastic effects include cells mutation as a result to radiation exposure. Dr. Einstein said "Deterministic effects occur only above the threshold dose, which typically is going to be high, and only after a large proportion of cells have been killed by radiation—which varies from individual to individual," Meanwhile, stochastic effects do not depend on high radiation doses, such effects can cause cancers after longer times up to 5 to 10 years. Dr. Einstein continued "What are the typical effective doses of cardiac studies using traditional protocols and how do we know that patients are not at risk of developing cancer downstream?"

Dr. Einstein said that cardiac imaging procedures vary in their effective doses according to several factors such as equipment, technicians’ experience, and the used technique. Currently, a diagnostic cardiac catheter involves delivering radiation of 7 mSv, CCTA procedures were usually including 15 mSv to 20 mSv few years ago. With the recent equipment, some cardiac imaging procedures will be carried out with less than 5 mSv. During the presentation, Dr. Einstein said that the effects of radiation exposure were evaluated on individuals who survived the atomic bomb attacks in Japan during World War II. However, he added that further large-scale studies are still needed to determine the effects of medical radiation exposure. He explained "Even though we need better epidemiological data, we think these low radiation doses [in cardiac imaging] can be related to developing an increased risk of malignancy. If these procedures were only used infrequently, there wouldn't be a potential public health problem,"