泪道放射性探针制备及其剂量学分布

Preparation and dose distribution of the radioactive lacrimal passages probe

目的制备泪道放射性探针并探讨其近距离照射治疗的有效剂量范围及安全性。方法^(125)I粒子内置热塑管中制成泪道放射性探针,对其进行温度、压力、浸泡、冲击试验,应用热释光法测量其在体模及蜡模中的剂量学分布。结果泪道放射性探针温度、压力、浸泡实验结果示探针无变形,表面放射性污染＜185 Bq。冲击实验结果示探针压扁变形,但表面放射性污染＜185 Bq。在蜡模及人体等效模型中剂量学测量结果示:在1～12 mm范围内,与探针距离每增加1 mm单位时间内的吸收剂量差异有显著性(P＜0．05);在12～40 mm范围内,相邻测量组间的吸收剂量差异无显著性(P＞0．05)。结论采用泪道放射性探针近距离照射治疗,在符合相关安全标准的同时,泪道狭窄处组织可获得有效治疗剂量,其有望成为治疗泪道再狭窄的新方法。

Objective To prepare radioactive lacrimal passages probe and observe the dose distribution in phantom, also to explore the effective doses range and safety for brachytherapy. Methods Radio- active probe was prepared by putting 125Ⅰ seeds into plastic tubes. Then, temperature, pressure, soaking and, shocking tests to the probe were performed. The dose distributions in body phantom and wax matrix were detected through thermoluminescent techniques. Results The external appearance of radioactive lacrimal passage probe had no changes through temperature, pressure and soaking tests, with a surface radioactive contamination dose lower than 185 Bq. However, the probe was flattened in shocking tests, meanwhile the surface radioactive contamination dose still lower than 185 Bq. The dose detection in body phantom and wax matrix showed that within the range from 1 mm to 12 mm away from the tube, the absorbed dose （AD） had statistic significances as the distance increased every 1 mm（P 〈0.05）. However, in range from 12 mm to 40 mm, no significant difference was found （ P 〉 0.05 ）. Conclusions The dose rates of the lacrimal passages probe for brachytherapy is within the safety limits for effective therapy. It will be a new and effective product for clinical treatment of lacrimal passage restenosis.