术中放疗深度剂量、表面剂量及漏射线的剂量研究

Study of Depth Fose, Skin Dose and Leakage Ray in Intra-operative Radiation Therapy

目的:研究术中放疗深度剂量、表面剂量及漏射线的剂量的测量方法,总结临床应用经验。方法:使用IC-15电离室和WELLHOFER WP700蓝水箱测量加速器电子束术中放疗限光筒中心轴百分深度剂量和表面剂量;采用Farmer剂量仪2570及有机玻璃小水箱,测量剂量输出因子及限光筒外漏射线。结果:6MeV和9MeV表面剂量分别为85.9%、87.2%。12MeV、16MeV、20MeV限光筒外1cm处漏射线分别达到6.81%、6.10%、6.85%。结论:术中放疗是一种复杂的治疗技术,在临床辐射剂量学上有其独特性。术中放疗表面剂量应该满足90%,建议增加填充物,如盐水纱布等,提高表面剂量。限光筒外的泄漏射线必须小于中心轴最大剂量的5%,做好肿瘤周围正常组织的辐射防护很重要。

Objective： To study the measurement and realization of depth dose, skin dose and leakage ray, and conclude somexperience of clinical application in Intra-operative Radiation Therapy. Methods： The depth dose on the beam central axis and the skin dose from electrons of the accelerator with the applicator for intraoperative radiotherapy were measured using IC-15 ionization chamber in WELLHOFER WP700 water phantom. The dose output factor and the leakage ray were measured by 2571A ionization chamber in water phantom. Results： The skin dose of 6 MeV and 9 MeV are separately 85.9%, 87.2%, the lcakage dose at 1 cm outside the applicator of 12 MeV, 16 MeV, 20 MeV are separately 6.81%, 6.10%, 6.85%. Conclusions： Intra-operative radiation therapy is a duplicate technique, it has many special characteristics in clinical radiation dosimetry. The skin dose of intra-operative radiation required above 90%, we suggest filling with compensation, such as gauze with salt water to improve the skin dose. The leakage dose outside the applicator must less than 5% of the maxim dose on the beam central axis, it is important to protect the normal tissue surround the tumor.