早期乳腺癌保乳术后全乳腺放射治疗cVMAT和fIMRT物理计划的剂量比较和分析  

Dose comparison and analysis between cVMAT and fIMRT physical scheme for whole breast radiotherapy after breast-conserving surgery of early left-sided breast cancer

作　　者：柏晗[1,2,3] 侯宇 李文辉[1,2] 李岚[1,2] 龙清[1,2] 赵毅[1,2] 

机构地区：[1]云南省肿瘤医院放射治疗中心,云南昆明650118 [2]昆明医科大学第三附属医院放射治疗中心,云南昆明650118 [3]云南省粒子天体物理重点实验室,云南昆明650118

出　　处：《生物医学工程与临床》2017年第6期619-623,共5页Biomedical Engineering and Clinical Medicine

摘　　要：目的为早期左乳腺癌保乳术后全乳腺放射治疗探寻合适的物理计划设计方案。方法随机选择10例接受保乳术后的左侧乳腺癌患者,年龄35~55岁,平均年龄42.5岁。在pinnacle TPS中为每例患者分别设计持续容积旋转调强放射治疗(c VMAT)和五野调强放射治疗(f IMRT)2种物理计划。比较和分析2种物理计划中体内的计划靶区(PTVin)的适形指数(CI)、均匀性指数(HI)、梯度指数(GI),以及同侧肺、心脏、对侧肺、对侧乳腺的剂量。结果c VMAT计划靶区的CI平均值为0.90(统计值0.90±0.02),HI平均值为0.12(统计值0.12±0.01),优于f IMRT计划靶区的CI平均值[0.85(统计值0.85±0.05)]、HI平均值[0.13(统计值0.13±0.01)];两种计划比较,差异有显著统计学意义(P=0.001、0.006)。当剂量>2 000 c Gy时,c VMAT的GI值始终小于f IMRT。两种物理计划在同侧肺的V_5、V_(10)、V_(20)、V_(30)、V_(40)、肺的平均剂量(MLD)上的差异均无统计学意义(P>0.05);两种物理计划在心脏的V_5、V_(10)、心脏的平均剂量(MHD)上的差异也无统计学意义(P>0.05)。但c VMAT中对侧肺的V_5、V_(10)、V_(20)、MLD均高于f IMRT计划,差异有统计学意义(P<0.05);且c VMAT中对侧乳腺的乳腺平均剂量(MBD)也高于f IMRT计划,差异有显著统计学意义(P<0.01)。结论c VMAT能实现更好的靶区剂量均匀性、适形度及更快的剂量跌落,虽然增加了对侧乳腺和对侧肺的剂量,但仍然远低于2个危及器官的剂量阈值。所以,c VMAT仍然是全乳腺放射治疗一种可供选择的放射治疗方式。ObjectiveTo search the suitable physical schemes for the whole-breast radiotherapy after breast-conserving surgery of left-sided breast cancer.Methods Ten cases of left-sided breast cancer with breast-conserving surgery were enrolled,which aged 35-55 years old with mean age of 42.5 years old.Two physical schemes,continuous volumetric modulated arc therapy（c VMAT）and five-field intensity modulated radiation therapy（f IMRT）were designed for every patient in pinnacle TPS.The conformal index（CI）,homogeneity index（HI）and gradient index（GI）in planning target volume（PTVin）and the dose of ipsilateral lung,heart,contralateral lung and contralateral breast in 2 physical schemes were compared and analyzed.Results The mean CI of c VMAT plan target was 0.90（0.90±0.02）and mean HI was 0.12（0.12±0.01）,which were superior to mean CI[0.85（0.85±0.05）]and mean HI[0.13（0.13±0.01）]of f IMRT;there was statistically significant differences between 2 physical schemes（P=0.001,0.006）.The dose2 000 c Gy,the GI of c VMAT was always smaller than that of f IMRT.There were no statistical differences in ipsilateral lung of V5,V（10）,V（20）,V（30）,V（40）,lung mean dose（MLD）between 2 physical schemes（P0.05）;There was no statistical difference in heart of V5,V（10）,heart mean dose（MHD）between 2 physical schemes（P〉0.05）.However,the V5,V（10）,V（20）and MLD of contralateral lung were higher than those of f IMRT,and the difference was statistically significant（P〉0.05）;The mean breast dose（MBD）of c VMAT was higher than that of f IMRT,and there was significant statistical significance（P〈0.01）.Conclusion It is demonstrated that the CI and HI in the target volume and dose-fall of c VMAT are superior to those of f IMRT,and c VMAT increased dose in contralateral lung and contralateral breast significantly lower than theradiation dose threshold of 2 organs at risk. So, c VMAT is still an alternative radiotherapy for the whole-breast radiotherapy.

关 键 词：全乳腺放射治疗 持续容积旋转调强放射治疗(cVMAT) 五野调强放射治疗(fIMRT) 放射剂量 

分 类 号：R730.55[医药卫生—肿瘤] R737.9[医药卫生—临床医学]