Impacts of the frequency of orthogonal image guided-verification on set-up error correction and PTV margins in postoperative radiotherapy for breast cancer
10.3760/cma.j.cn112271-20240516-00180
- VernacularTitle:乳腺癌术后放疗正交图像引导频率对摆位误差校正及外放边界的影响
- Author:
Fangfen DONG
1
;
Bing WU
;
Zhixin WANG
;
Jiaming LI
;
Miaoyun HUANG
;
Yong YANG
;
Benhua XU
;
Xiaobo LI
Author Information
1. 福建医科大学附属协和医院放疗科 福建省肿瘤智能影像与精准放疗重点实验室 福建省消化、血液系统与乳腺恶性肿瘤放射与治疗临床医学研究中心，福州 350001
- Publication Type:Journal Article
- Keywords:
Breast cancer;
Image-guided frequency;
Set-up error;
Planning target volume margin
- From:
Chinese Journal of Radiological Medicine and Protection
2025;45(1):37-42
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the impacts of different frequencies of orthogonal image-guided verification on set-up error correction and the reference values of planning target volume (PTV) margins in postoperative radiotherapy for breast cancer, in order to provide recommendations of the verification frequency in clinical practice.Methods:A total of 80 breast cancer patients who received postoperative intensity-modulated radiotherapy for breast cancer at the Affiliated Union Hospital of Fujian Medical University from January 2021 to January 2022 were enrolled. Orthogonal image-guided verification was conducted before each radiation treatment to determine initial and residual set-up errors. The error data were statistically analyzed by categorizing patients into groups A, B, C, D, E, and F, based on assumed verification frequencies (daily, every 2, 3, 4, and 5 d, and no correction). The magnitude, distribution, and differences of set-up errors of various groups were analyzed, and the PTV margins were calculated using a reference formula.Results:The collected initial set-up errors of the 80 patients were (3.49±3.43), (2.87±2.88), and (2.75±2.35) mm, in x, y, and z directions, respectively. The residual set-up errors decreased gradually with increasing verification frequency. In the case of daily image-guided verification, the residual set-up errors in x, y, and z directions decreased to (1.63±0.90), (1.63±0.93), and (1.55±0.90)mm, respectively. The reference values of PTV margins calculated under different verification frequencies decreased with an increase in the verification frequency. Under daily verification, the reference values of PTV margins calculated based on set-up errors decreased from initial 6.60, 6.29, and 4.22 mm (without correction) to 1.27, 1.37, and 1.28 mm, respectively. Differences in the reference values under verification frequencies every 3, 4, and 5 d were less than 0.81 mm. Conclusions:Daily image-guided verification (including correction) can effectively reduce set-up errors in image-guided radiotherapy for breast cancer. The set-up errors differ under varying verification frequencies, with a higher frequency corresponding to better correction effects and smaller PTV margins required.
