Radiotherapy
Factors associated with set-up errors in intensity-modulated radiotherapy after breast conserving surgery
Xiao Xu, Minna Zhang, Bin Wang, Kan Wu, Jiahao Wang, Lixia Xu, Xiadong Li, Jian Liu, Bing Xia
Published 2019-06-25
Cite as Chin J Radiol Med Prot, 2019, 39(6): 434-438. DOI: 10.3760/cma.j.issn.0254-5098.2019.06.006
Abstract
ObjectiveTo evaluate the difference of set-up errors between thermoplastic mask and breast bracket in patients receiving intensity-modulated radiotherapy after breast conserving surgery, and the impact of clinical factors associated with set-up errors.
MethodsA total of 34 patients treated with intensity-modulated radiotherapy after breast conserving surgery from January 2016 to June 2018 were reviewed. Eighteen patients were fixed with thermoplastic mask, and sixteen were with breast bracket. Weekly CBCT scan records were used to analyze set-up errors, and group systematic and random errors were computed. The influence of clinical factors on set-up errors was also analyzed.
ResultsThe immobilization technique with thermoplastic mask showed great superior in comparison with breast bracket; however, only in the Ty (translation) and Ry (rotation), the differences had significance. Based on group systematic and random errors, PTV margins in Tx, Ty and Tzwere 2.65, 4.36 and 2.87 mm in thermoplastic mask group, as well as 5.71, 6.07 and 4.20 mm in breast bracket group, respectively. Multi-factor regression analysis showed that BMI was independent factors affecting set-up errors.
ConclusionsCompared with breast bracket, the immobilization technique with thermoplastic mask has the potential of reducing set-up errors and PTV margins in patients receiving intensity-modulated radiotherapy after breast conserving surgery, especially in patients with high BMI.
Key words:
Breast cancer; Radiotherapy; Thermoplastic mask; Set-up error
Contributor Information
Xiao Xu
Department of Radiation Oncology, Hangzhou Cancer Hospital, Hangzhou 310002, China
Minna Zhang
Department of Radiation Oncology, Hangzhou Cancer Hospital, Hangzhou 310002, China
Bin Wang
Department of Radiation Oncology, Hangzhou Cancer Hospital, Hangzhou 310002, China
Kan Wu
Department of Radiation Oncology, Hangzhou Cancer Hospital, Hangzhou 310002, China
Jiahao Wang
Department of Radiation Oncology, Hangzhou Cancer Hospital, Hangzhou 310002, China
Lixia Xu
Department of Radiation Oncology, Hangzhou Cancer Hospital, Hangzhou 310002, China
Xiadong Li
Department of Radiation Oncology, Hangzhou Cancer Hospital, Hangzhou 310002, China
Jian Liu
Department of Breast Surgery, Affiliated Hangzhou First People′s Hospital, Zhejiang University School of Medicine, Hangzhou 310006, China
Bing Xia
Department of Radiation Oncology, Hangzhou Cancer Hospital, Hangzhou 310002, China
