^32P持续低剂量率辐射敷贴治疗的胶片剂量验证

目的：对^32P的敷贴治疗进行胶片剂量验证。方法：直线加速器建立25—575cGy的胶片辐射剂量曲线。放射性核素^32P溶液4．14MBq吸附在1．1cm×1．2cm的长方形滤纸上制成放射性敷贴器。将20张1．5cm×1．5cm的辐射直接显色（RC）胶片（胶片厚0．225mm）重叠放置（总厚度4．5mm），把放射性敷贴器放置在最顶端，辐射0．5小时。通过辐射剂量曲线计算每张胶片辐射剂量，根据胶片厚度推算距离敷贴器不同距离处的辐射剂量，并绘制相应的剂量-距离曲线。结果：距离敷贴器0、0．225、0．45、0．675、0．9、1．125、1．35、1．8、2．025、2．25、2．475mm处的0．5小时辐射测量吸收剂量为265、175、120、98、68、55、39、25、19、16、12、5cGy，拟合曲线为Y：257．28e^-1.4521X。结论：放射性核素^32P敷贴器的辐射剂量随距离增加呈指数方式衰减，敷贴器表面和2．5mm处的辐射剂量相差约53倍。

The quantitative radiation dose by RC film for the continued low - dose - rate radiation of ^32P

Objective：To study the distribution of radiation dose in space of ^32P by EBT films. Methods： The curve of radiation dose and grey scale of film from 25 to 575cGy was built by linear accelerator. The radionuclide of ^32P was dripped on 1. 1cm × 1.2cm filter paper. The twenty 1.5cm × 1.5cm RC films （ thick film 0. 225mm ） were overlap together （ total thickness 4.5mm） and the filter paper of ^32P were placed on the top. There were 0.5 hours irradiation and the twenty films radiation dose were measured by standard curve. According to the thickness of film and radiation dose, the curve of radiation dose and distance was distributed. Results： The absorbed dose of the films at 0, 0. 225 ,0. 45 ,0. 675,0.9,1. 125,1.35,1.8,2. 025,2.25,2. 475mm place were 265,175,120,98,68,55,39,25,19, 16,12,5 cGy. The fitting curve was Y = 257.28e^- 1 4521X. Conclusion： The radiation dose of radionuclide 32p were decayed in distance by index mode and there was 53 times difference between the surface and 2.5mm distance of the ^ 32P.