Organ Doses And Associated Cancer Risks For CT Examinations Of Thorax

The use of computed tomography (CT) is increasing rapidly and doses are not negligible especially when medical procedures require more than one CT scan. The objectives of the present study were to measure doses in/on an anthropomorphic Rando phantom during standard and low dose CT protocols of thorax and to estimate radiation risks for adult patients that undergo multiple CT scans of thorax. Thermoluminescent (TL) and radiophotoluminescent (RPL) dosimeters were used for dose measurements. Radiation risks of cancer incidence, in the form of lifetime attributable risk (LAR), were estimated using BEIR VII model. For five exposures with standard protocol mean organ doses were 94 mGy (breast), 85 mGy (stomach), 85 mGy (thyroid), 78 mGy (lung), 52 mGy (liver) and 16 mGy (colon). For the standard CT protocol associated LARs were found to be up to 0.401 percent (401 breast cancers per 105 exposed patients) and 0.116 percent (116 lung cancers per 105 exposed patients) for women and men, respectively. The low dose protocol reduces doses (and risks) by the average factor of 5 and therefore the use of the low dose protocol is recommended whenever it is medically justified. (author).