This study aimed to investigate unwanted radiation exposure of radiosensitive organs during computed tomography (CT) scans of the hand. Furthermore, we investigated the effectiveness of a shield in reducing unwanted radiation exposure. In a prospective observational study, the patients were randomized to receive a shield during the hand CT scan. Two group of patients were further randomized to undergo multi-detector CT (MDCT) or cone-beam CT (CBCT). The radiation dose was measured in the target point and the nearest skin surface of radiosensitive organs by attached the thermoluminescent dosemeter chips. When shielding was performed, the radiation doses had decreased significantly with a mean of 79% (65-91%) in the MDCT group and 88.6% (85-93%) in the CBCT group. In the non-shielded group, the radiation doses to the radiosensitive organs decreased inversely with increasing distance, which means that the closer the target point is, the more unwanted radiation exposure increases. It is important to keep radiosensitive organs as far as possible from the target point during CT scan. In particular, it is necessary to shield the radiosensitive organs closer to the target point. Level of Evidence: Level II, Prospective observational study.