Abstract 2621: Influence of Age, Gender, and Scan Protocol on Cancer Risk from 64-Slice Computed Tomography Coronary Angiography: Insights from the National Research Council’s Biological Effects of Ionizing Radiation VII Report
Background: Computed tomography coronary angiography (CTCA) has become a common diagnostic test, yet there is little data on its associated cancer risk. The recent Biological Effects of Ionizing Radiation (BEIR) VII Phase 2 report provides a framework for estimating the lifetime attributable risk (LAR) of cancer incidence from a CTCA study, using the most current data available on the health effects of radiation.
Methods: Organ doses from 64-slice CTCA to standardized phantom male and female patients were estimated using Monte Carlo methods based on the approach of the Gesellschaft für Strahlen- und Umweltforschung. Standard spiral CT protocols were employed, assuming a Siemens Somatom 64 scanner with voltage 120 kVp, current 170 mAs, slice thickness 0.6 mm, slice increment 3.8 mm, gantry rotation 0.33 seconds, and scan length 15 cm, both with and without electrocardiographically gated tube current modulation (TCM) resulting in a mean 35% reduction in current. Age-specific LARs of individual cancers were estimated using the approach of BEIR VII and summed to obtain whole-body LARs.
Results: Cancer risk estimates, summarized in the figure⇓, varied from 1 in 143 for a 20 year old female without TCM, to 1 in 5017 for an 80 year old male with TCM. Cancer risks to 60 year old men and women, using TCM, were 1 in 1911 and 1 in 715, respectively. The highest organ LARs were of lung cancer and, in younger women, breast cancer.
Conclusions: 64-slice CTCA is associated with a non-negligible LAR of cancer. These risks vary greatly, based on patient age, gender, and TCM use. Careful selection of patients for CTCA and careful optimization of scan protocol are imperative to minimize cancer risk.