非均整模式光子线在乳腺癌调强放疗的剂量学评估  

Evaluation of intensity-modulated radiotherapy using flattening filter free photon beams for patients with breast cancer

作　　者：吴丽丽[1] 张基永[1] 黄宝添[1] 陆佳扬[1] 林珠[1] 张武哲[1] 

机构地区：[1]汕头大学医学院附属肿瘤医院放疗科,广东汕头515041

出　　处：《中国医学物理学杂志》2017年第11期1086-1090,共5页Chinese Journal of Medical Physics

基　　金：国家自然科学基金青年基金(81602667);广东省医学科学技术研究基金(A2016592);汕头市医疗科技计划项目(汕府科[2015]123号)

摘　　要：目的:评估6 MV光子线高剂量率非均整模式(FFF)在右侧乳腺癌保乳术后大分割同步推量调强放疗(SIBIMRT)的可行性。方法:随机选取10例右侧乳腺癌保乳术后患者临床资料,分别给予瘤床靶区(PTV1)和全乳靶区(PTV2)处方剂量48 Gy和40 Gy,分15次照射。对每例患者分别制作FFF和均整模式(FF)两组SIB-IMRT计划,比较两组计划的靶区覆盖率、适形指数(CI)和均匀指数(HI)以及危及器官受量和计划执行效率。结果:两种计划靶区的覆盖率、HI和CI的差异幅度小于1%。FFF计划PTV1的D98%高于FF计划(t=-2.297,P<0.05);PTV2的D90%低于FF计划(t=2.479,P=0.019);PTV2的CI稍劣于FF计划(t=5.343,P<0.001)。FFF计划患侧肺的V_(4Gy)和V_(16Gy),健侧乳腺的D_(mean)和D_(5%),以及正常组织的D_(mean)、V_(5Gy)、V_(10Gy)和V_(20Gy)均低于FF计划(t=2.318~11.535,P<0.05);正常组织的V_(40Gy)(t=-2.967,P=0.016)和皮肤Dmean(t=-6.102,P<0.001)高于FF计划。FFF计划的MU值(1 417±230)高于FF计划MU值(1 106±208)(t=-8.220,P<0.001);照射时间比FF计划减少33%(t=11.788,P<0.001)。结论:两种模式均能满足临床要求,FFF模式高剂量率光子线更有利于保护危及器官,显著缩短照射时间,执行效率较高。Objective To evaluate the feasibility of 6 MV photon beam with flattening filter free （FFF） applied on hypofractionated simultaneous integrated boost intensity-modulated radiotherapy （SIB-IMRT） for patients receiving breast-conserving surgery for right-sided breast cancer. Methods The planning target volumes of tumor bed and breast （PTV1 and PTV2） of selected 10 patients treated with breast-conserving surgery for right-sided breast cancer were irradiated with 48 and 40 Gy in 15 fractions, respectively. For each case, SIB-IMRT plans with standard flattening filter （FF） mode and FFF mode were generated, respectively. The PTV coverage, conformity index （CI）, homogeneity index, dose to organs-at-risk, monitor unit and delivery time were compared between FFF plan and FF plan. Results The differences between 2 plans in PTV coverage, homogeneity index and CI were within 1%. Compared with FF plan, FFF plan provided slightly higher D98% for PTV1 （t=-2.297, P〈0.05）, lower D90% and inferior CI for PTV2 （t=2.479, P=0.019; t=5.343, P〈0.001）. FFF plans also provided better sparing for V4 Gy and V16 Gy of ipsilateral lung, Dmean and D5% of contralateral breast, and lower mean dose, V5 Gy, V10 Gy and V20 Gy for normal tissue （t=2.318-11.535, P〈0.05） as comparison with FF plan, while V40 Gy of normal tissue （t=-2.967, P=0.016） and skin mean dose （t=-6.102, P〈0.001） were higher in FFF plan than in FF plan. Moreover, the monitor unit of FFF plans was significantly higher than that of FF plans [（1 417±230） vs （1 106±208）; t=-8.220, P〈0.001） ]. However, the delivery times of FFF plan were 33% less than that of FF plans （t=11.788, P〈0.001）. Conclusion Both FF plan and FFF plan meets the clinical requirements, but FFF plan is associated with a better organs-at-risk sparing, remarkably shorter treatment time and higher treatment efficiency.

关 键 词：乳腺癌 高剂量率照射 非均整模式 同步推量调强放射治疗 

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