探究4种临床CT扫描方式对受检者辐射剂量的影响及胸部扫描辐射场的空间分布

目的 探究4种临床CT扫描方式对受检者常见组织吸收剂量的影响及胸部扫描的辐射场空间分布，以期为受检者与机房内空间辐射防护提供依据。方法 利用热释光探测器（TLD）测量仿真体模的眼晶体、甲状腺、性腺、胸部和腹部皮肤在4种CT扫描方式下的吸收剂量。利用TLD监测胸部螺旋扫描时距离CT诊断床不同位置处的空气比释动能。结果 仿真体模的眼晶体、甲状腺、性腺、胸部和腹部皮肤在4种CT扫描方式下的吸收剂量分别为0.040～64.818 mGy、0.154～10.155 mGy、0.028～0.154 mGy、0.443～17.141 mGy和0.093～14.346 mGy。胸部扫描时空间辐射场的空气比释动能最大值为0.049 mGy，且与CT球管距离越大数值越小。结论 4种CT扫描方式对受检者常见组织的吸收剂量一般不会超过阈剂量。单次CT胸部扫描时陪检者所受剂量较小。为减少辐射危害，在CT扫描中可采取屏蔽措施来减少受检者组织吸收剂量，同时陪检者应适当增加与球管和诊断床的距离。

Radiation doses to subjects in four clinical CT scanning modes and spatial distribution of chest scanning radiation field

Objective To explore the absorbed dose to the common tissues of subjects in four clinical CT scanning modes and the spatial distribution of the radiation field in chest scanning, in order to provide a basis for the radiation protection of subjects and the space in the machine room.Methods A thermoluminescence detector (TLD) was used to measure the absorbed doses to the eye lens, thyroid gland, gonad, chest and abdominal skins of the anthropomorphic phantom in four CT scanning modes. The TLD was used to monitor the air kerma at different positions from the CT diagnostic table during chest spiral scanning.Results The absorbed doses to the eye lens, thyroid gland, gonad, chest and abdominal skins of the anthropomorphic phantom in four CT scanning modes were 0.040-64.818 mGy, 0.154-10.155 mGy, 0.028-0.154 mGy, 0.443-17.141 mGy, and 0.093-14.346 mGy, respectively. The maximum air kerma value of the space radiation field during chest scanning was 0.049 mGy, and the farther the distance from the CT tube, the smaller the value.Conclusion The absorbed doses to the common tissues of subjects examined by the four CT scanning modes generally do not exceed the threshold doses. The dose received by the companion of the subject during a single chest CT scan was small. In order to minimize radiation hazards, shielding measures can be taken in CT scanning to reduce the absorbed doses to the tissues of the subject, and the companion of the subject should appropriately increase the distance from the tube and the diagnostic table.