Because the exposure to radiation from CT scanning is higher than that from other X-ray diagnostic devices, it is necessary to lower this exposure. In this study, we placed a protective seat on the abdomen and dorsal side of a human body phantom. Three different kinds of CT units, with a single detector, four detectors, and 16 detectors, were used to compare the absorbed dose on the skin surface and uterus. Head and chest CT scans were taken with the standard protocol. The difference in exposure to the uterus with and without the protective shield was found to be small. Exposure to the skin surface was about 0.2 mGy without the protective seat. We found that the exposure dose to chest could be reduced as much as 50% by using the protective seat. Effective radiation differs depending on the institution, and these differences can be more than the amount that can be reduced by using the protective seat. Thus, we conclude that it is important for each institution to determine the best protocol optimization for each individual.