全身放射治疗的剂量测量研究

目的:在全身放射治疗条件下,测量直线加速器空气中射线场均匀性,水模体内剂量分布情况,以及不同规格水模体的百分深度剂量值。方法:将加速器的源皮距(SSD)延长至450 cm,机架头旋转为90°,准直器开到最大,治疗头旋转为45°,形成菱形射野,使用剂量测量仪:PTW-UNIDOS,电离室:PTW 30001,测量Varian Clinac 2100C直线加速器的剂量值。结果与结论:加速器在空气中射线场剂量:T方向上总的平均值为5.147,绝对误差为5.8%,归一后相对误差达到;G方向上总的平均值为5.124,绝对误差为5.1%,归一后相对误差达到;此加速器的射线场均匀性可以用于全身放射治疗。水模体内剂量分布情况,在10 cm深度处,平均剂量值为8.960,归一数据中的绝对误差为;在20 cm深度处,平均剂量为6.381,从归一数据中的绝对误差为。

Dosimetry of Total Body Irradiation

Objective： Under the condition of the total body irradiation, measure linear accelerator ray field uniformity in the air, water phantom dose distribution, and the percentage depth dose values of different specification water phantom. Methods： The accelerator source skin distance （SSD） be extended to 450 cm, head rack rotation is 90° , collimator at maximum, treatment of head rotation of 45° , the formation of diamond radiation field, using dose meter： PTW-UNIDOS, ionization Room： PTW 30001, measure Varian Clinae 2100C linear accelerator dose value. Result and Conclusions： Accelerator radiation field air dose： T di- rection the total average value is 5.147,the absolute error is 5.8%,relative error after normalization is ：1：5.15%; G direction the to- tal average value is 5.124, the absolute error is 5.1%, after normalization relative error is ± 4.1%. This accelerator ray field uni- formity can be used for total body radiation therapy. Water phantom dose distribution in depth of 10era, the average dose value is 8.960, the normalized absolute error is ±3.05%; at 20cm depth of the average dose is 6.381, the normalized absolute error is±2.25%.