摘要
目的分析肿瘤放射治疗中人体不规则轮廓对剂量分布的影响,比较各种临床修正方法的优劣。方法先数学推导计算有效源皮距方法的公式,然后基于西门子MD7745加速器6 MV-X线和15MV-X线百分深度剂量表(PDD)、组织最大剂量比表(TMR),针对典型人体曲面,分别使用有效源皮距方法、组织空气比/组织最大比方法、等剂量线移动方法计算兴趣点剂量。结果3种剂量修正方法计算值偏差在1%以内,计算工作量差别也不大,但修正原理有所区别。结论应使用有效源皮距方法或组织空气比/组织最大比方法来修正人体不规则轮廓对剂量分布的影响,且有效源皮距方法的公式应以DA=Dm×PDD(SSD,r1,d)×(SSD+d)2(SSD+h+d)2代替DA=Dm×PDD(SSD,r,d)×(SSD+dm)2(SSD+h+dm)2为好。
Objective To analyze the influence of curved or irregular body surface on the dose distribution, and compare and evaluate the different correction methods in clinical use. Methods First, we deduced the formula for the effective source skin distance（SSD） method, then we used the effective SSD method, the ratio of tissue air ratios/tissure maximum ratios （TARs/TMRs） method and the isodose chart shift method to calculate the dose for a typical curved body. Results The deviation among three methods was less than 1%, and the amount of work for calculation was similar, however the different theory was used in each method. Conclusion The effective SSD method or the ratio of TARs/TMRs method should be used to calculate the dose for curved body surface. In addition, formula DA = Dm × PDD（ SSD,rl ,d） × （ SSD ＋ d）^2/（ SSD ＋ h ＋ d）^2is recommended to replace the formula DA = Dm × PDD （ SSD, r, d） × （ SSD ＋dm）^2/（ SSD ＋ h ＋dm）^2when applying the effective SSD method.
出处
《现代医学》
2008年第1期27-29,共3页
Modern Medical Journal
