Study of setup error in cone beam CT for whole breast intensity-modulated radiotherapy with breast board immobilization
10.3760/cma.j.issn.1004-4221.2019.07.012
- VernacularTitle:乳腺托架固定下全乳调强放疗CBCT测定摆位误差的研究
- Author:
Shufei YU
1
,
2
;
Shulian WANG
;
Yu TANG
;
Yongwen SONG
;
Siye CHEN
;
Minghui LI
;
Jing JIN
;
Yueping LIU
;
Hui FANG
;
Bo CHEN
;
Shunan QI
;
Ning LI
;
Yuan TANG
;
Ningning LU
;
Yexiong LI
Author Information
1. 国家癌症中心/国家肿瘤临床医学研究中心/中国医学科学院北京协和医学院肿瘤医院放疗科 100021
2. 首都医科大学附属北京朝阳医院肿瘤科 100020
- Keywords:
Breast neoplasm/radiotherapy;
Cone-beam CT;
Setup error;
Margin
- From:
Chinese Journal of Radiation Oncology
2019;28(7):532-535
- CountryChina
- Language:Chinese
-
Abstract:
Objective To investigate the setup errors and influencing factors of the whole breast intensity-modulated radiotherapy (IMRT) after breast-conserving surgery,and to identify the margins from clinical target volume (CTV) to planning target volume (PTV).Methods Thirty patients with left-sided (n=15) or right-sided breast cancer (n=15) receiving whole breast hypofractionated IMRT with breast board immobilization after breast-conserving surgery in Cancer Hospital from 2016 to 2017 were enrolled.The kilo-voltage cone-beam computed tomography (CBCT) was used to compare the errors of planning CT and treatment unit and determine the setup errors.The margins from CTV to PTV were calculated.The setup errors under different conditions were statistically compared by t-test.Results A total of 151 sets of CBCT images were taken in the whole cohort,(5.0± 1.3) sets per patient on average.The setup errors in the x-axis (left-right direction),y-axis (cranial-caudal direction) and z-axis (anterior-posterior direction) were (2.2± 1.7) mm,(3.1±2.5) mm and (3.3±2.3) mm,respectively.The margins from CTV to PTV were 6.39 mm,10.00 mm and 8.57 mm,respectively.The setup error in anterior-posterior direction in the first week was (3.7±2.5) mm,significantly larger than (2.6±1.6) mm in the following week (P=0.002).The setup error of the patients with overweight or obesity was (3.9±2.6) mm,significantly higher than (2.9±2.0) mm in those with normal weight in the z-axis direction (P=0.033).Conclusion The margins from CTV to PTV are recommended to be ranged from 6 to 10 mm during hypofractionated whole breast IMRT with breast board immobilization after breast-conserving surgery.More frequent imaging verification should be applied in the first week of IMRT.
