Study of setup error and dosimetry of postoperative intensity-modulated radiotherapy for breast cancer using skin lead marker and iSCOUT image-guided positioning system
10.3760/cma.j.cn113030-20210317-00111
- VernacularTitle:体表铅点标记辅助iSCOUT图像引导定位系统在乳腺癌术后调强放疗应用研究
- Author:
Fangfen DONG
1
;
Liyan DAI
;
Miaoyun HUANG
;
Xing WENG
;
Liuqing JIANG
;
Benhua XU
;
Xiaobo LI
Author Information
1. 福建医科大学医学技术与工程学院 福建医科大学临床医学部 福建医科大学肿瘤中心，福州 350122
- Keywords:
Skin lead marker;
iSCOUT system;
Breast neoplasm/radiotherapy;
Setup error;
Margin
- From:
Chinese Journal of Radiation Oncology
2021;30(10):1059-1064
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the application value of skin lead marker combined with iSCOUT image-guided positioning system in monitoring and correcting the setup error of intensity-modulated radiotherapy (IMRT) for breast cancer and calculate the PTV margin, aiming to provide reference for clinical practice.Methods:25 breast cancer patients treated with IMRT after modified radical mastectomy in Fujian Medical University Union Hospital from April to August 2019 were enrolled in this study. The skin lead marker combined with iSCOUT image-guided positioning system was employed for image-guided positioning based on the gold standard registration algorithm. Initial setup errors on the x (lateral), y (craniocaudal) and z (anteroposterior) axis and residual errors after the position correction were recorded and analyzed. The effect of the errors before and after image-guided correction upon the plan dose was compared and the reasonable PTV margin was calculated.Results:25 patients received 150 times of positioning verification using skin lead marker combined with iSCOUT image-guided positioning system. The absolute residual errors on the x-, y-and z-axis were (1.53±0.96), (1.30±0.99) and (1.34±0.92) mm, significantly smaller than the initial setup errors of (2.63±2.12), (2.41±2.45) and (3.07±2.77) mm (all P<0.001). The percentage of dose deviation due to residual errors was also smaller than that of the initial errors. Significant differences were observed in D 98%, D 2%, D max of PTV, D max of the heart, D max of the healthy breast, and D mean of the affected lung and both lungs. The percentage deviation from the original plan was decreased from 2.18%, 3.19%, 10.66%, 8.75%, 48.21%, 10.50%, and 3.66% to 0.38%, 0.23%, 2.31%, 0.04%, 13.78%, 6.35% and 0.41%, respectively (all P<0.05). PTV margins on the x-, y-and z-axis after correction were calculated as 1.87, 1.75 and 1.69 mm, respectively. Conclusion:It is feasible and valuable to apply the skin lead marker combined with iSCOUT image-guided positioning system in the positioning verification and correction of breast cancer radiotherapy position, providing novel reference for clinical PTV margin.
