^(125)I籽源组织间放射治疗剂量测定

Dosimetry of^(125)I seed interstitial brachytherapy

目的 对12 5I籽源组织间放射治疗的剂量分布进行测定和评价。方法 12 5I籽源活度为每粒 12 .2MBq。在体模上d 15mm圆周植入 2 0粒 ,在前列腺模型上分 4层植入 70粒 ,分别用Far mar 2 5 70辐射剂量仪和热释光剂量计 (TLD) 2种方法对靶区中心部位吸收剂量率进行测定 ,另用柯达感光胶片测量等剂量曲线分布图。结果 2种方法测定结果在体模上圆周靶区中心吸收剂量率分别为 8.4cGy/h和 7.9cGy/h ,前列腺模型靶区中心部吸收剂量率分别为 12 .0cGy/h和 11.1cGy/h。前列腺靶区接受总累积吸收剂量为 2 4 2 19cGy。等剂量曲线表明 ,离前列腺中心 4cm其它组织受照剂量陡降为中心的 10 %。结论 上述 2种方法测定籽源在靶区中心剂量值基本相符。

Objective To calibrate and assess the dose distribution of 125 I seed brachytherapy. Methods Twenty 125 I seeds, each with activity of 12.2 MBq, were implanted on the circumference of a circle 15mm across in a phantom. Into a designed prostate model, 70 125 I seeds were implanted in four planes. The absorbed dose rate of the target volume was monitored by Farmar 2570 dosimeter and thermoluminescence dosimeters (TLD) with the isodose curves drawn on Kodak films. Results The central dose rates of the circular target volume assessed by Farmar 2570 and TLD were 8.4, 7.9 cGy/h in the phantom and 12.0, 11.1 cGy/h in the prostate model. For the target volume of the prostate model, the total absorbed dose was 24?219 cGy. The dose rate 4 cm from the prostate cancer as shown by the isodose curves was only 10% of the central dose rate. Conclusion The central dose rate of target volume measured by the two methods are similar.