Radiation exposure in multi-slice CT of the heart

Purpose: To assess radiation exposure of patients undergoing Multi-Row Dete ctor CT (Multi-Slice CT, MSCT) of the heart. Material and Methods: Four dif ferent cardiac MSCT protocols with changing slice collimation (4x1, and 4x2 .5 mm), and pitch-factor (1.5, 1.8, and 4) were examined. An anthropomorphi c Alderson-Rando phantom was equipped with LiF-thermoluminescent dosimeters at several organ sites, and effective doses were calculated using ICRP-wei ghting factors. These data were compared to data From standard MSCT of ches t and abdomen. Results: Effective dose in different protocols for cardiac M SCT varies from 2.8 to 10.3 mSv (male), and from 3.6 to 12.7 mSv (female). In protocols with thin collimation and low pitch or a combination of severa l heart examinations, radiation exposure may be comparable to the effective dose of standard MSCT of the chest (male: 11.9 mSv, female: 12.9 mSv) or t he abdomen (male: 16.1 mSv, female: 15.7 mSv). Highest organ doses were fou nd for the female breast (up to 46.6 mGy), and the lungs (up to 36.4 mGy) w ith surface doses as high as 54.3 mGy. Conclusions: Cardiac MSCT adds signi ficantly to the radiation exposure of patients and can reach the effective dose applied by standard MSCT of chest or abdomen.