用TLD测量X射线全身照射的体内相对剂量分布

MEASUREMENT OF RELATIVE DOSE DISTRIBUTION OF PATIENT IN TOTAL BODY IRRADIATION WITH TLD

采用热释光探测器 ( TLD)对人体体模内各点剂量及肺剂量进行模拟实际照射的测量 ,从而对接受全身照射的病人体内剂量 ,特别是肺剂量进行预测量。结果表明 ,体模中心轴线上剂量分布的均匀度( Homogeneity)小于± 14.5%。证明了我们的摆位方法可行 ,可以用于 X射线全身照射治疗。

The Alderson standard phantom was irradiated and the dose distribution in the Alderson Phantom was measured. According to the real radiation treatment conditions and setting up conditions of patients who will receive TBI, we used Farmer Ionization Chamber to estimate the absolute absorbed dose and used TLD to estimate the relative dose distribution in the Phantom. The energy of X ray used in TBI was 6 MV. The source and skin distance was 450 cm. In order to improve the surface dose, a plastic plate was put in front of the Alderson Phantom just like what we do in TBI. The thickness of the plastic plate was 1 cm. The dose rate in the middle of the Phantom was 5.5 cGy per minute. The dose inhomogeneity in the Alderson Phantom besides its head is smaller than +10%. The dose inhomogeneity in the whole body amounts to ±14.5%. The inhomogeneity of surface dose is up to 95%. The measuring results demonstrated that our setting up method for the TBI patients are good and could be adopted in TBI. (