直肠癌术前容积调强放射治疗计划子野形状控制参数优化研究  

Aperture shape controller parameter optimization of volumetric modulated radiotherapy plans in preoperative radiotherapy for rectal cancer

作　　者：弓健[1] 姚凯宁 王美娇[1] 张健[1] 蒋璠 张艺宝[1] 吴昊[1] 岳海振[1] GONG Jian;YAO Kai-ning;WANG Mei-jiao;ZHANG Jian;JIANG Fan;ZHANG Yi-bao;WU Hao;YUE Hai-zhen(Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education/Beijing),Department of Radiotherapy,Peking University Cancer Hospital&Institute,Beijing 100142,China)

机构地区：[1]北京大学肿瘤医院暨北京市肿瘤防治研究所放疗科·恶性肿瘤发病机制及转化研究教育部重点实验室,北京100142

出　　处：《中华肿瘤防治杂志》2021年第8期626-632,共7页Chinese Journal of Cancer Prevention and Treatment

基　　金：北京市自然科学基金(1202009);北京市医管局培育计划(PX2019042);教育部科技发展中心产学研创新基金-“智融兴教”基金(2018A01019);中央高校基本科研业务费/北京大学临床医学+X青年专项(PKU2020LCXQ019);国家重点研发计划资助(2019YFF01014405)。

摘　　要：目的通过对比美国Varian公司Eclipse治疗计划系统(版本号15.5)光子优化算法中子野形状控制(ASC)参数对直肠癌术前容积调强放射治疗(VMAT)计划的剂量学评价指标和治疗计划传递精度的影响,旨在探索适合该病例的优选ASC参数,从而为后期治疗提供剂量学保障。方法选取2019-03-12-2019-08-05在北京大学肿瘤医院放疗科进行直肠癌术前VMAT治疗的20例患者资料,计划肿瘤靶区(PGTV)和计划靶区(PTV)处方剂量分别为50.6 Gy/22次和41.8 Gy/22次。治疗计划方案均采用常规单个全弧的布野方式,保持其他优化目标函数和正向剂量计算算法不变的条件下,仅修改6个ASC可选调制强度参数Off、Very low(VL)、Low(L)、Moderate(M)、High(H)和Very high(VH)后进行无监督自动优化计算并生成6组治疗计划,通过对比子野复杂性指数(ACM)、跳数、平均剂量体积直方图(MDVH)、靶区的均匀性指数(HI)、适形度指数(CI)、D_(mean)以及股骨头(FH)、膀胱(UB)的D_(mean)、D50%等剂量学评价指标,以Off组为参考,正态性检验后采用配对样本t检验或相关样本非参数检验对比分析并确定适合该病例的ASC参数设置。结果6组治疗计划获得可比拟的靶区MDVH,均可满足临床要求;FH和UB的MDVH与ASC参数调制强度呈正相关;对于HI参数,相对于Off组,HI_(PTV)的M组(t=-4.114,P=0.001)、H组(t=-3.068,P=0.006)和VH组(Z=-2.725,P=0.006)差异有统计学意义,而HI_(PGTV)除了L组以外差异均有统计学意义,t值分别为-2.199、-3.020、-3.065和-3.517,P值分别为0.040、0.007、0.006和0.002;对于CI参数,仅CIPTV数据的VH组(t=-4.057,P=0.001)、CIPGTV的M组(Z=-2.091,P=0.037)和VH组(Z=-2.165,P=0.030)差异有统计学意义;对于D_(mean)参数,PTV的M组(t=-3.549,P=0.002)和VH组(Z=-3.667,P=0.002),PGTV的M组(t=-2.645,P=0.016)、H组(t=-3.480,P=0.003)和VH组(t=-3.616,P=0.002)等强调制条件下差异有统计学意义,而除了危及器官UB的VH组(t=-2.477,P=0.023)、FH的H组(t=-2Objective To investigate aperture shape controller(ASC)of photon optimization algorithm in Varian Eclipse 15.5 Treatment planning system(TPS)and its effect on dosimetric index and dose delivery to pre-surgical rectal cancer patient with volumetric modulated arc therapy(VMAT)technique,in order to explore the optimal ASC to guarantee the effect of radiotherapy.Methods Twenty VMAT treatment plans(PGTV/PTV:50.6 Gy/41.8 Gy/22 fractions)with single full-arc field for pre-surgical rectal cancer were selected in Beijing Cancer Hospital from March 12 th to August 5 th 2019.Six level of ASC parameters(off,very low,low,moderate,high and very high)were chosen to generate six treatment plans while keeping other optimization objective functions and dose calculation algorithm unchanged.By comparing a series of mechanical and DVH related parameters for different ASC parameter levels,suitable ASC parameter settings were analyzed and determined.The studied parameters included:Aperture complexity metric(ACM),monitor units(MU),the mean dose volume histogram(MDVH),homogeneity index(HI),conformity index(CI),D_(mean),D50%of femoral head(FH)and urinary bladder(UB).Compared with the off group,the paired sample t test or related sample non-parametric test was used after the normality test.Results The mean DVH for target volume were comparable for six ASC levels,whereas the MDVHs for FH and UB were positively correlated with ASC level.As for HI parameters,there were significant differences in Moderate group(t=-4.114,P=0.001),high group(t=-3.068,P=0.006)and very high group(Z=2.725,P=0.006)for HI_(PTV),while four groups of the HI_(PGTV) had statistically significant differences(t values were-2.199,-3.020,-3.065,-3.517;P values were 0.040,0.007,0.006,0.002)except the low group.As for HI parameters,compared with the off group,there were significant differences in moderate group(t=4.114,P=0.001),high group(t=-3.068,P=0.006)and very high group(Z=-2.725,P=0.006)for HI_(PTV),while for the HI_(PGTV),four groups had statistically significant differe

关 键 词：形状控制参数 适形度指数 均匀性指数 子野复杂性指数 

分 类 号：R735.37[医药卫生—肿瘤]