电子射野影像系统在测量调强放疗三维剂量上的应用  

Electronic Portal Imaging Devices in 3D Dose Measurement for Intensity Modulated Radiotherapy

作　　者：胡银祥 王志勇[2] 金海洁 苏胜发 毕婷 罗元强[2] 金风 卢冰 Hu Yinxiang;Wang Zhiyong;Jin Haijie;Su Shengfa;Bi Ting;Luo Yuanqiang;Jin Feng;Lu Bing(Department of Oncology,Guizhou Cancer Hospital&the Affiliated Hospital of Guizhou Medical University,Gui Yang 550004,Guizhou,China;Department of Oncology,Guizhou Cancer Hospital,Guiyang 550004,Guizhou,China)

机构地区：[1]贵州医科大学附属医院/贵州省肿瘤医院肿瘤科,贵阳550004 [2]贵州省肿瘤医院肿瘤科,贵阳550004

出　　处：《肿瘤预防与治疗》2021年第1期41-47,共7页Journal of Cancer Control And Treatment

基　　金：贵州省科技计划项目(编号:黔科合LH字[2016]7398)。

摘　　要：目的∶采用三维γ分析与靶区平均剂量评估电子射野影像系统(elecronic portal imaging device,EPID)在测量调强放疗三维剂量上的应用特点。方法;首先在固体水模体中测试规则野和调强野,分析点剂量、平面γ通过率及靶区三维γ通过率的模型重建精度;再采用EPID测量80例鼻咽癌患者调强放射治疗(intrnsit mdlund raliahera-py,MRT),基于CT重建治疗前三维剂量,分析靶区三维γ通过率和平均剂量;最后抽取其中12例分析空腔修正对三维γ通过率和靶区剂量的影响。结果∶IMRT在固体水模体中三维剂量重建的等中心点剂量平均偏差为-1.09%±1.27%,二维平面γ通过率为99.38%,固体水模体计划靶区(planing turget volume,PTV)三维γ通过率为98.01%;基于CT重建80例鼻咽癌患者IMRT剂量分布,PTV的3%/3mm和5%/3mm三维γ通过率分别为89.71%±5.71%和96.36%±3.02%;其中12例患者PTVI与原发肿瘤靶区的三维γ通过率(3%/3mm)分别为91.20%±3.5%和87.70%±8.07%,经过空腔密度修正后通过率分别为%.80%±2.15%和97.90%±3.41%,修正前后有统计学差异(1=-7.214,P<0.001;=-4.263,P=0.001),修正前后重建平均剂量的偏差分别为0.70%±1.30%和0.60%±2.05%,差异无统计学意义(1=-1.910,P=0.083;1=1.083,P=0.30)。结论∶三维γ分析是三维剂量验证可靠的质控方法,修正空腔密度可提升靶区三维γ通过率,而对平均剂量影响小,分析评估靶区平均剂量对三维剂量验证具有临床应用价值。Objective:To evaluate the application of electronic portal imaging devices(EPID)in 3D dose measurement for intensity modulated radiation therapy(IMRT)by 3D 7 analysis and average target dose.Methods:Regular fields and IMRT fields were first tested in the solid water phantom to analyze the model reconstruction accuracy of point dose,planar γ pass rate and 3D γ pass rate of targets.EPID was then used to measure IMRT in 80 patients with nasopharyngeal carcinoma.3D γ pass rates and average doses were analyzed based on 3D dose before CT reconstruction.12 cases were finally selected to analyze the effect of cavity correction on 3D γ pass rates and target doses.Results:The average isodose deviation of 3D dose reconstruction for IMRT in solid water phantom was-1.09%±1.27%;the 2D y pass rate was 99.38%;and the 3D γ pass rate of planning target volume(PTV)was 98.01%.For the 80 nasopharyngeal carcinoma patients undergoing CT reconstruction,3D γ pass rates of PTV with 3%/3 mm and 5%/3 mm criteria were 89.71%±5.71%and 96.36%±3.02%,respectively.The 7 pass rates(3%/3 mm)of PTV1 and the gross tumor volume of nasopharynx in 12 cases were 91.20%±3.53%and 87.70%±8.07%before cavity correction;and they became 96.80%±2.15%and 97.9%±3.41%after cavity correction;There were statistically significant differences before and after the correction(t=-7.214,P<0.001=-4.263=0.001).The average dose deviation before and after reconstruction were 0.70%±1.30%and 0.60%±2.05%;and the difference was not significant(t=-1.910,P=0.083;t=1.083=0.302).Conclusion:3D y analysis is reliable in quality assurance for 3D dose verification.Cavity correction could improve 3D γ pass rates of the target,but has litde effect on the average dose.The analysis and evaluation of the average dose of the target is clinically applicable and valuable for 3D dose verification.

关 键 词：电子射野影像系统 三维剂量重建 调强放疗 γ分析 

分 类 号：R730.55[医药卫生—肿瘤] R815.2[医药卫生—临床医学]