分次间随机摆位误差对早期乳腺癌大分割放疗中靶区和危及器官剂量分布的影响  

Effect of inter-fractional random set-up error between simulated fractions on dose distribution of target and organs at risk in hypofractionated radiotherapy after breast-conserving surgery for early breast cancer

作　　者：王钦 倪文婕 王秀楠 杨慧 张富利 WANG Qin;NI Wenjie;WANG Xiunan;YANG Hui;ZHANG Fuli(Department of Radiotherapy,Beijing Shijitan Hospital,Beijing 100038,China;Department of Radiotherapy,the Seventh Medical Center of Chinese PLA General Hospital,Beijing 100700,China)

机构地区：[1]首都医科大学附属北京世纪坛医院放疗科,北京100038 [2]解放军总医院第七医学中心放疗科,北京100700

出　　处：《重庆医学》2023年第12期1822-1826,共5页Chongqing medicine

摘　　要：目的研究分次间随机摆位误差对早期乳腺癌大分割放疗中靶区及危及器官剂量分布的影响。方法应用直线加速器的X线容积成像(XVI)系统在放射治疗前行锥形束CT扫描(CBCT)获取随机摆位误差数据。随机抽取首都医科大学附属北京世纪坛医院2020年10月到2021年8月已完成左侧乳腺癌保乳术后大分割放射治疗的14例患者的计划。调取患者CBCT图像42幅,应用统计学软件计算头(Y+)、脚(Y-)、左(X+)、右(X-)、腹(Z+)、背(Z-)三维方向的误差最大值与均值。在Monaco5.11治疗计划系统中,通过移动临床治疗中心的方式,分别向患者6个方向移动最大误差值,在保证子野数、出束跳数不变的情况下,重新计算获得实验计划(E)并与临床计划(C)进行剂量学对比。结果CBCT结果表明在头(Y+)、脚(Y-)、右(X-)方向随机摆位误差最大值为5 mm;实验计划和临床计划对比显示:95%的瘤床加量区瘤床计划靶区(PTV_(boost))和全乳计划靶区(PTV)体积的受照剂量(D_(95))整体下降在5%之内,2%的PTV_(boost)体积的受照剂量(D_(2))在向患者左(X+)和腹(Z+)侧出现误差时产生高于110%处方量的剂量;对于危及器官而言,患侧肺、健侧肺、健侧乳腺、脊髓均未超过剂量限值,但是心脏和冠状动脉左前降支在左(X+)、右(X-)和腹(Z+)、背(Z-)方向上对随机摆位误差的影响比较敏感,尤其是向左(X+)侧和腹(Z+)侧的摆位误差导致剂量增加最为明显。结论5 mm摆位误差对PTV影响不大,但对PTV_(boost)可能存在处方剂量覆盖不全的风险,同时可能增加心脏毒性,在临床中应引起重视。Objective To study the effect of inter-fractional random set-up error on target and organs at risk(OARs)dose distribution in early breast cancer hypofractionated radiotherapy.Methods The X-ray volume imaging(XVI)system in linear accelerator was used Cone Beam CT(CBCT)scan to obtain random set-up error data.A total of 14 patients with hypofractionated radiotherapy for left breast cancer from October 2020 to August 2021 were randomly selected.A total of 42 CBCT images of the patients were collected,and statistical software was used to calculate the maximum and mean error values in the three dimensions of head(Y+),foot(Y-),left(X+),right(X-),abdomen(Z+)and back(Z-).In the Monaco5.11 treatment planning system,the maximum error values were input to the TPS in six directions of three dimensions by moving the clinical treatment center,respectively.Under the condition of keeping the number of subfields and beam jumps unchanged,the experimental plan(E)was recalculated and compared with the clinical treatment plan(C)in dosimetry.Results CBCT results showed that the maximum error value of random set-up in the head(Y+),foot(Y-),and right(X-)direction was 5 mm;The comparison between the experimental plan and the clinical plan showed that the overall decline of PTV and PTV_(boost)dose covered by the volume of 95%target area(D_(95))was within 5%.High dose in the volume of PTV_(boost)(D_(2))exceeded 110%of the prescription dose when errors occurred to the left(X+)and abdominal(Z+)sides of the patient.For OARs,the ipsilateral lung,contralateral lung,contralateral breast and spinal cord did not exceed the dose limit,but the influence of random set-up error on the heart and coronary left anterior descending artery branch in left(X+),right(X-),abdomen(Z+)and back(Z-)was sensitive.In particular,the random set-up error to the left(X+)and ventral(Z+)side resulted in the most significant dose increase.Conclusion The inter-fractional random set-up error has little effect on PTV,However,there may be a risk of incomplete dose coverage volu

关 键 词：分次间随机摆位误差 早期乳腺癌 大分割放射治疗 锥形束CT扫描 剂量分布 

分 类 号：R730.55[医药卫生—肿瘤]