Analysis of setup errors in dual-isocenter breath-hold radiotherapy after left-sided breast cancer surgery
10.3760/cma.j.cn113030-20240627-00252
- VernacularTitle:左乳腺癌术后双等中心屏气放疗摆位误差分析
- Author:
Zhiqing XIAO
1
;
Xiaotong LIN
1
;
Miao WANG
1
;
Yanqiang WANG
1
;
Han GUO
1
;
Lei TIAN
1
;
Yanjiao WU
1
;
Wenyan WANG
1
;
Junling LIU
1
;
Xiuwu LI
1
;
Xiaoying XUE
1
Author Information
1. 河北医科大学第二医院放疗科，石家庄 050000
- Publication Type:Journal Article
- Keywords:
Breast neoplasms;
Deep-inspiration breath-hold;
Dual-isocenter;
Setup error;
Cone-beam CT
- From:
Chinese Journal of Radiation Oncology
2025;34(5):468-475
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the impact of different target sites, number of treatments, and age on setup errors in dual-isocenter radiotherapy for breast cancer, and to provide a basis for planning target volume (PTV) margin expansion.Methods:A retrospective analysis was conducted on data from 15 patients with left-sided breast cancer who underwent dual-isocenter breath-hold radiotherapy in the Department of Radiotherapy Oncology at the Second Hospital of Hebei Medical University from May 2021 to May 2023. Setup errors were acquired using a Varian TrueBeam STX linear accelerator. Patients were grouped by target site (supraclavicular/chest wall), treatment phase (early/late), and age (younger/older). Non-parametric tests were used to analyze differences in setup errors in : vertical (Vrt), longitudinal (Lng), lateral (Lat) directions, and pitch, roll, and rotation (Rtn) angles. The formula proposed by van Herk was applied to calculate PTV margins.Results:The Vrt direction setup error in the supraclavicular region (0.2 cm) was smaller than that in the chest wall region (0.26 cm), but errors and margin expansions in other directions were larger ( P<0.05 for Lng and Lat directions). No significant correlation was observed in Vrt direction errors between the two sites ( P=0.062), while significant correlations were found in the other directions and angles (all P<0.05). As treatment progressed, setup errors increased in the Vrt and Rtn directions for the supraclavicular region, and in the Vrt, Lng, Lat directions and Rtn angle for the chest wall region. Among these, only the increase in Lat direction error for the chest wall region was statistically significant ( P=0.028). The PTV margins in the late phase group (except for the Lat direction of the supraclavicular region) were greater than or equal to those in the early phase group. Elderly patients had significantly larger setup errors than younger patients in Vrt, Lng, and Lat directions for the supraclavicular region, as well as in Vrt and Lat directions for the chest wall region (all P<0.05). Conclusions:In dual-isocenter radiotherapy for breast cancer, the supraclavicular region requires larger PTV margins than the chest wall region, and elderly patients require greater margins overall. Mid-course rescanning is recommended. If cone-beam CT guidance cannot be ensured for every session, expansion of PTV margins should be considered for the supraclavicular region and elderly patients to reduce the risk of geographic miss.
