Radiation safety measures in diagnostic nuclear medicine, based on the potential radiation dose emitted by radioactive patients

Abstract Objective: To measure the potential radiation dose emitted by patients who have recently undergone diagnostic nuclear medicine procedures, in order to establish optimal radiation safety measures for such procedures. Materials and Methods: We evaluated the radiation doses emitted by 175 adult patients in whom technetium-99m, iodine-131, and fluorine-18 radionuclides were administered for bone, kidney, heart, brain, and whole-body scans, as measured with a radiation detector. Those values served as the basis for evaluating whole-body radiopharmaceutical clearance, as well as the risk for the exposure of others to radiation, depending on the time elapsed since administration of the radiopharmaceutical. Results: The mean time to clearance of the radiopharmaceuticals administered, expressed as the effective half-life, ranged from 1.18 ± 0.30 h to 11.41 ± 0.02 h, and the mean maximum cumulative radiation dose at 1.0 m from the patients was 149.74 ± 56.72 µSv. Even at a distance of 0.5 m, the cumulative dose was found to be only half and one tenth of the limits established for exposure of the general public and family members/caregivers (1.0 mSv and 5.0 mSv per episode, respectively). Conclusion: Cumulative radiation doses emitted by patients immediately after diagnostic nuclear medicine procedures are considerably lower than the limits established by the International Commission on Radiological Protection and the International Atomic Energy Agency, and precautionary measures to avoid radiation exposure are therefore not required after such procedures.

摘要
研究目的：检测近期接受诊断性核医学检查的患者所释放的潜在辐射剂量，为此类检查制定最优辐射安全防护方案。
材料与方法：本研究通过辐射探测器，对175名成人患者的体外辐射释放剂量进行评估。受试患者均接受了锝-99m（technetium-99m）、碘-131（iodine-131）及氟-18（fluorine-18）放射性核素注射，分别用于骨骼、肾脏、心脏、脑部及全身显像。以测量所得剂量数据为基础，评估全身放射性药物的清除情况，并结合放射性药物注射后的时间跨度，测算他人遭受辐射暴露的风险。
结果：以有效半衰期表示的放射性药物平均清除时间范围为1.18±0.30 h至11.41±0.02 h；患者体外1.0 m处的平均最大累积辐射剂量为149.74±56.72 µSv。即便在0.5 m的近距离处，累积辐射剂量也仅分别为普通公众与家属/护理人员暴露限值的二分之一与十分之一（单次检查的限值分别为1.0 mSv与5.0 mSv）。
结论：诊断性核医学检查后即刻，患者释放的累积辐射剂量远低于国际放射防护委员会（International Commission on Radiological Protection, ICRP）与国际原子能机构（International Atomic Energy Agency, IAEA）制定的安全限值，因此此类检查后无需采取额外的辐射暴露防护措施。