鼻咽癌动态调强放疗计划的剂量学验证  

Plan-specific dosimetric verification for nasopharyngeal carcinoma patient treated with dynamic intensity-modulated radiation therapy

作　　者：肖锋[1] 孙朝阳[1] 石梅[1] 张学成[1] 陆宙[1] 陆军[1] 刘晓莉[1] 

机构地区：[1]第四军医大学西京医院放疗科,陕西西安710032

出　　处：《现代肿瘤医学》2007年第2期178-180,共3页Journal of Modern Oncology

摘　　要：目的建立鼻咽癌动态调强放疗计划的剂量学验证方法。方法对80例鼻咽癌动态调强放疗计划分别进行3个项目的剂量验证一是用电离室在人体等效模体中测量靶区参考点的绝对剂量,二是使用二维电离室矩阵测量调强计划每个射野的剂量强度分布,三是使用慢感光胶片竖插在模体内,测量调强计划横断面的剂量分布。结果92.5%计划靶区参考点的绝对剂量误差小于5%,在改用体积较小的电离室和调整机架角度避开固定装置重新制定计划后,所有计划靶区参考点的绝对剂量误差也都小于5%。有88.1%的照射野剂量分布误差小于3%。结论为了得到更加真实的测量结果,建议所有测量,尤其是绝对剂量测量都在计划实际机架角度下进行。利用二维电离室矩阵可定量分析照射野剂量分布误差,并且省时省力,有利于验证工作的常规化。胶片法验证由于费时费力且误差较大已趋于淘汰。对于动态调强计划,模体计划各个射野的机器跳数(MU)应与实际计划相同,这样才能得到更加真实的测量结果。Objective ： To establish a method of plan - specific dosimetric verification for patient with nasopharyngeal carcinoma（NPC） treated with dynamic intensity -modulated radiation therapy. Methods： Eighty patients with NPC were treated with dynamic intensity - modulated radiation therapy and the procedure was composed of three kinds of measurements, one was the absolute dose at the reference point of target volume with an ionization chamber, second was the intensity map for each individual beam with 2D ionization chamber array,and third the relative dose distribution of transverse plane with film. Because taking along, cost a lot and had error to measure with film, we just performed 8 patients. Results： The absolute dose errors of 92.5% plans were within 5% using 0.6cc ice chamber and all the absolute dose errors of every reference point of target volume were within 5% when using 0. 14cc ice chamber or adjust the gantry angle to evade the immovable device redesigning the plans. The dose distribution errors of 88.1% individual beam was within 3%. Conclusions： To get more correct measurement results we should perform especially absolute dose measurements under the gantry angle of effective plan. It is helpful to normalize the verification by using 2D ionization chamber array to quantificational analyze dose errors economically, and it will no longer to use film for its shortcomings. As for dynamic intensity - modulated radiation therapy, the MU in every field of phantom plan should be the same with effective plan to get more correct measurement results.

关 键 词：鼻咽癌 动态调强放疗 放射治疗计划 剂量验证 

分 类 号：R739.63[医药卫生—肿瘤]