前列腺癌三种放疗技术的剂量学研究

摘要

目的在前列腺癌含盆腔淋巴引流区放疗计划中比较常规放疗(conventional radiotherapy,CRT)、三维适形放疗(three-dimensional conformal radiotherapy,3D-CRT)和同步加量束流调强放疗(Simultaneous Modulated Accelerated Radiation Therapy,SMART)三种技术的剂量学差异.方法对分期 T2-3N0M0的10例前列腺癌患者行 CT 扫描,勾画靶区及危及器官,分别设计以上三种计划,予相同处方剂量,前列腺和精囊70Gy,盆腔淋巴引流区50Gy.采用等剂量分布曲线,剂量-体积直方图,靶区的 Dmax、Dmin、Dmean、V95%、适形指数、剂量均匀性指数及正常组织所受剂量来比较计划.结果 PTV1、PTV2靶区适形性和 PTV2的剂量分布均匀性 SMART 较3D-CRT 更佳,3D-CRT 较 CRT 更佳(P <0.05),PTV1的剂量分布均匀性 CRT 较3D-CRT 及 SMART 更佳.对直肠和股骨头的保护 SMART 优于3D-CRT,3D-CRT 优于 CRT(P <0.05).对膀胱的保护 SMART 优于3D-CRT 和 CRT(P <0.05),3D-CRT 和 CRT 相比较优势不明显.对小肠和结肠的保护三种方式没有差异(P <0.05).结论综合靶区和正常组织,SMART 优于3D-CRT,3D-CRT 优于 CRT,SMART 对含淋巴引流区的前列腺癌放疗具有优势%　　Objective To compare the dosimetry differences of conventional radiotherapy(CRT), three-dimensional conformal radiotherapy (3D-CRT) and simultaneous modulated accelerated radiation therapy(SMART) in treatment planning of prostate cancer including pelvic cavity prophylactic irradiation. Methods The planning CT scans of ten patients with prostate cancer with staging of T2-3N0M0 were used to generate CRT、3D-CRT and SMART plans for this study. Target volume and organ at risk were contoured on the individual axial CT slices. Three different treatment plannings were designed for each patient with a prescription dose of 70Gy to prostate and seminal vesicle and 50Gy to pelvic lymph node. The following parameters of plannings were compared in each patient:isodose distributions line,dose-volume histogram (DVH),Dmax,Dmin,Dmean,V95%,CI(radiation conformal index,CI)、HI(relative dose homogeneity index,HI)and the dose to related critical organs. Results SMART showed better dose uniformity and conformity than 3D-CRT and CRT,and 3D-CRT was superior to CRT except in PTV1(P<0.05).SMART was superior to 3D-CRT,and 3D-CRT was superior to CRT in sparing rectum and femoral head (P<0.05). SMART was superior to 3D-CRT and 3D-CRT in sparing bladder (P <0.05).But the dose received by the intestine and colon were not significant different(P<0.05).Conclusion Considering the target volume and critical organs,plans of SMART were superior to 3D-CRT and 3D-CRT were superior to CRT.SMART showed advantages in prostate cancer radiotherapy with nodal treatment.