Mass screening with CT colonography: should the radiation exposure be of concern?
OBJECTIVE
Computed tomography colonography (CTC), particularly using noncathartic techniques, has the clear potential to increase compliance for colorectal cancer screening. Because the geometry for CTC is highly advantageous, it can be performed with lower radiation doses than almost any other CT examination. If CTC were to become a standard screening tool for the population age 50 years and older, the potential market in the United States would soon be over 100 million people. Therefore, it is pertinent to consider the radiation exposure and any potential radiation risk to the population from such a mass CTC screening program.


METHODS
Organ doses from CTC examinations can be estimated with standard techniques. These doses can be applied to organ- and dose-specific radiation cancer risk estimates to estimate the excess cancer risk resulting from the radiation from a paired (supine and prone) CTC examination.


RESULTS
The cancer risks associated with the radiation exposure from CTC are unlikely to be zero, but they are small. A best estimate for the absolute lifetime cancer risk associated with the radiation exposure using typical current scanner techniques is about 0.14% for paired CTC scans for a 50-year-old, and about half that for a 70-year-old. These values probably could be reduced by factors of 5 or 10 with optimized CTC protocols.


CONCLUSIONS
In terms of the radiation exposure, the benefit-risk ratio potentially is large for CTC.
Brenner
David J
DJ
Center for Radiological Research, Columbia University Medical Center, New York, New York 10032, USA. djb3@columbia.edu
Georgsson
Maria A
MA
D023881:Colonography, Computed Tomographic / Q000009:adverse effects*; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology; D006801:Humans; D008403:Mass Screening / Q000009:adverse effects*; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D011829:Radiation Dosage; D012307:Risk Factors