^(60)Co重过滤低剂量率照射剂量学

Dosimetry of ^(60)Co γ-ray Low Dose Irradiation on Spleen

目的:探讨低剂量60Coγ射线照射由于照射物理条件不同剂量学参数的变化。材料和方法:在常规照射和低熔点铅(LML)重过滤初始γ束条件下,用三维水箱自动测量装置和剂量仪分别测量PDD、OAR和绝对剂量定标后的K修正系数。结果:60Coγ射线初始束经重过滤后PDD在人体脾脏靶区深度5cm～11cm区域平均降低1.2个百分点,OAR较常规60CoOAR圆弧化,绝对剂量较常规实际减弱80倍,并给出了治疗时间公式。讨论:对60Coγ射线的重过滤,是采用常规60Coγ射线治疗机实现低剂量辐射照射脾脏的最佳方法。

Objective: To study the dosimetry of Heavy Filter Low Dose Rate(HFLDR) 60Co γ-ray under the different physical conditions. Material and methods: The values of PDD, OAR and the correct factor K of absolute dose were measured with 3D-water-tank, and Farmer 2570 dosimeter for open fields and low melting point lead heavy filter fields, respectively. Results: The average PDD of low-melting point lead heavy filter fielts is 1.2 percent lower that those of open fields on 5 cm～11 cm depth, the OAR is more blunt for low-melting point lead heavy filter fields than open fields,absolute dose for open fields were 80 times higher than those of low-melting point lead heavy filter fields, respectively, and the formula calculating the therapeutic time was established. Conclusions: The optimal way applying the low dose rate 60Co γ-ray for irradiating the spleen is discussed in the text.