加速器碳素纤维床对三维治疗计划剂量分布的影响  

The effect of carbon fiber couch on dose distribution of conformal intensity modulated plan

作　　者：付庆国[1] 朱小东[1] 杨海明[1] 魏党[1] 刘志杰[1] 

机构地区：[1]广西壮族自治区肿瘤医院放疗科,南宁530021

出　　处：《中华放射肿瘤学杂志》2014年第6期505-509,共5页Chinese Journal of Radiation Oncology

摘　　要：目的 评估加速器碳素纤维床对放疗计划剂量分布及验证通过率的影响.方法 在Pinnacle8.0m计划系统中建立治疗床模型,修正10例鼻咽癌、10例宫颈癌和10例胸肺部放疗计划后斜入射野的剂量计算.评估碳素纤维床对放疗计划剂量分布的影响.利用三维验证设备Delta4实测放疗计划,比较在剂量计算中考虑进碳素纤维床后γ通过率的改进程度.结果 TPS剂量计算考虑治疗床后靶区所受剂量明显减少[（4772～7266） cGy：（4859～7347） cGy,P=0.000～0.002],D95的相对偏差为1％ ～3％.Delta4验证的γ通过率（3 mm/3％标准）均有所提高（96.4％～98.8 ％：93.4％～97.3％,P =0.000）.结论 若TPS剂量计算时不考虑治疗床的存在则靶区所受剂量将被高估,这对靶区剂量响应梯度小的肿瘤更应引起足够重视.Objective To evaluate the effect of carbon fiber couch on dose distribution of radiotherapy planning and verification pass rate.Methods Establishing the carbon fiber treatment couch model in Pinnacle8.0m Treatment Planning system （TPS）,and then this model was used to correct dose calculations of oblique fields in the treatment plans of 10 cases of nasopharyngeal carcinoma,10 cases of breast cancer and 10 cases of lung cancer and evaluate the effect of carbon fiber couch on the whole dose distribution of the plans.Then these plans were measured by three-dimensional dose verification equipment Delta4 to confirm the improvement extent of Gamma pass rate after considering the carbon fiber treatment couch.Results For the majority of plans,when the carbon fiber couch was taken into consideration,the target doses was significantly reduced （4772 cGy-7266 cGy vs.4859 cGy-7347 cGy,P=0.000-0.002） and the relative deviation of D95 was 1％ to 3％.Measurement results of Delta4 showed that Gamma pass rate （3 mm/3％ criteria） increased in all plans （96.4％-98.8％ vs.93.4％-97.3％,P =0.000）,some of that were up to 5 percentage when the couch model was applied.Conclusions Target doses will be overestimated if the treatment couch is ignored in TPS measurement.,However it should arouse enough attention when the disease with smaller doses corresponding gradient.

关 键 词：碳素纤维床 三维治疗计划 剂量分布 γ通过率 

分 类 号：R730.55[医药卫生—肿瘤]