^(125)I粒子链管内近距离治疗剂量分布的计算研究

Dose Distribution Calculation of the Luminal Brachytherapy by ^(125)I seed Chains

目的研究125I粒子链管内近距离治疗恶性管腔狭窄的粒子链剂量分布情况。方法研究对象6711型125I种子源,假设种子源初始活度均为1mCi,粒子链是由沿着粒子长轴方向无间隔紧密直线排列的粒子构成的。依据美国医学物理家协会工作组43号报告(AAPMTGNo.43)及其更新报告中的剂量计算模型以及相应的参数和实验数据,以单枚剂量计算模型为基础,利用"标量叠加"的方法,从理论上推导并得到多枚粒子剂量计算的数学模型。结果依据多枚粒子剂量计算模型和参数,通过计算分别得到:距离由10枚和20枚粒子所组成的粒子链中心点垂直距离为0.5cm和1cm以及端点垂直距离为0.5cm和1cm处的剂量率(单位:cGy/h)和经过1周、2周和4周以后的吸收剂量(单位:Gy)。结论上述计算结果为应用125I粒子链管内近距离治疗恶性管腔狭窄提供了理论上的剂量学依据。

Objective To study dose distribution of 125I seed chains on the luminal brachytherapy of malignant luminal stenosis. Methods The research object was the Model 6711 125I seed source. The initial activity of seed source was assumed 1 mCi. The seed chains were composed of seed sources along the long axis, and the seed sources were no interval and linear arrangements. According to the American Association of Physicists in Medicine （AAPM） TG-43 and TG-43UI protocols, the dose calculation model, the corresponding parameters and experimental data were provided. Based on the model of single dose calculation, the dose calculation model of multiple seed sources was derived by the method of the scalar superposition. Results Based on the dose calculation model and parameters of multiple seed sources, the was made seed chains up of 10 and 20 seed sources, and the points of dose rate and absorbed dose calculation were located in the vertical distances of 0.5 cm and 1 cm distancing from the centre point and end point of the particle chains. The dose rate of the seed chains on the points was calculated, and the absorbed dose was also calculated after one week, two weeks and four weeks. Conclusion The research results provide the theoretical bases of dosimetry on the luminal brachytherapy of malignant luminal stenosis by using the 125I seed chains.