PECIAL REPORTS AND REVIEWS ass Screening With CT Colonography : Should the Radiation xposure Be of Concern ?

c ackground & Aims: Computed tomography colonograhy (CTC), particularly using noncathartic techniques, as the clear potential to increase compliance for coloectal cancer screening. Because the geometry for CTC s highly advantageous, it can be performed with lower adiation doses than almost any other CT examination. If TC were to become a standard screening tool for the opulation age 50 years and older, the potential market n the United States would soon be over 100 million eople. Therefore, it is pertinent to consider the radiaion exposure and any potential radiation risk to the opulation from such a mass CTC screening program. ethods: Organ doses from CTC examinations can be stimated with standard techniques. These doses can e applied to organand dose-specific radiation cancer isk estimates to estimate the excess cancer risk resultng from the radiation from a paired (supine and prone) TC examination. Results: The cancer risks associated ith the radiation exposure from CTC are unlikely to be ero, but they are small. A best estimate for the absolute ifetime cancer risk associated with the radiation expoure using typical current scanner techniques is about .14% for paired CTC scans for a 50-year-old, and about alf that for a 70-year-old. These values probably could e reduced by factors of 5 or 10 with optimized CTC rotocols. Conclusions: In terms of the radiation expoure, the benefit-risk ratio potentially is large for CTC.