Anglesio Silvia, Calamia Elisa, Fiandra Christian, Giglioli Francesca Romana, Ragona Riccardo, Ricardi Umberto, Ropolo Roberto
SC Fisica Sanitaria 1, Azienda Ospedaliera S Giovanni Battista di Torino, Italy.
Tumori. 2005 Jul-Aug;91(4):335-8. doi: 10.1177/030089160509100410.
Brachytherapy for prostate cancer by means of permanently implanted 125I sources is a well established procedure. An increasing number of patients all over the world are treated with this modality. When the technique was introduced at our institution, radiation protection issues relative to this technique were investigated in order to comply with international recommendations and national regulations. Particular attention was paid to the need for patient shielding after discharge from hospital.
The effective and equivalent doses to personnel related to implantation, the effective dose to patient relatives as computed by a developed algorithm, the air kerma strength values for the radioactive sources certified by the manufacturer compared with those measured by a well chamber, and the effectiveness of lead gloves in shielding the hands were evaluated.
The effective dose to the bodies of personnel protected by a lead apron proved to be negligible. The mean equivalent doses to the physician's hands was 420 microSv for one implant; the technician's hands received 65 microSv. The mean air kerma rate measured at the anterior skin surface of the patient who had received an implant was 55 microGy/h (range, 10-115) and was negligible with lead protection. The measured and certified air kerma strength for125I seeds in RAPID Strand corresponded within a margin of +/- 5%. The measured attenuation by lead gloves in operative conditions was about 80%. We also defined the recommendations to be given to the patient at discharge.
The exposure risks related to brachytherapy with 125I to operators and public are limited. However, alternation of operators should be considered to minimize exposure. Patient-related measurements should verify the dose rate around the patient to evaluate the need for shielding and to define appropriate radiation protection recommendations.
通过永久植入125I粒子源进行前列腺癌近距离放射治疗是一种成熟的方法。全球接受这种治疗方式的患者数量日益增加。当该技术引入我们机构时，为符合国际建议和国家规定，对与该技术相关的辐射防护问题进行了调查。特别关注了患者出院后的防护需求。
评估了与植入相关的人员有效剂量和当量剂量、通过开发的算法计算得出的患者亲属有效剂量、制造商认证的放射源空气比释动能强度值与电离室测量值的比较，以及铅手套对手部的屏蔽效果。
事实证明，佩戴铅围裙保护的人员身体所受有效剂量可忽略不计。一次植入操作中，医生手部的平均当量剂量为420微希沃特；技术人员手部接受的剂量为65微希沃特。接受植入治疗的患者前皮肤表面测得的平均空气比释动能率为55微戈瑞/小时（范围为10 - 115），有铅防护时可忽略不计。RAPID Strand中125I粒子的测量空气比释动能强度与认证值的误差在±5%以内。铅手套在手术条件下的测量衰减约为80%。我们还确定了出院时应给予患者的建议。
125I近距离放射治疗对操作人员和公众的暴露风险有限。然而，应考虑轮换操作人员以尽量减少暴露。与患者相关的测量应核实患者周围的剂量率，以评估防护需求并确定适当的辐射防护建议。
