Analysis and verification of target margin for post-mastectomy radiotherapy for breast cancer(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2021年第7期
- Page:
- 804-808
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Analysis and verification of target margin for post-mastectomy radiotherapy for breast cancer
- Author(s):
- SHEN Zhengwen; LI Shi; TAN Xia; TIAN Xiumei; LUO Huanli; JIN Fu; WAN Yue
- Department of Radiation Oncology, Chongqing University Cancer Hospital, Chongqing 400030, China
- Keywords:
- Keywords: breast cancer post-mastectomy radiotherapy cone-beam computed tomography setup error margin dosimetric effect
- PACS:
- R318；R811
- DOI:
- DOI:10.3969/j.issn.1005-202X.2021.07.003
- Abstract:
- Abstract: Objective To calculate the CTV-PTV margins based on the retrospective analysis on the setup errors of post-mastectomy radiotherapy for breast cancer, and to simulate the setup errors for verifying whether the margin is appropriate. Methods Forty breast cancer patients, including 20 patients with left-sided breast cancer and 20 patients with right-sided breast cancer, who received post-mastectomy radiotherapy were enrolled. According to the CBCT images collected during the treatment, the setup errors were determined, and the margins were calculated. The setup errors were simulated in TPS for comparing the dosimetric differences under the target margins. Results The setup errors in left-right, superior-inferior and anterior-posterior directions were (2.09±2.48), (2.57±2.52) and (2.88±2.54) mm, respectively, and the CTV-PTV margins were 6.24, 7.99 and 7.17 mm, respectively. There were statistically significant differences in D95, D98, Dmax and Dmin of PTV, Dmax and Dmean of the unaffected breast and Dmax of spinal cord, but not in the dosimetric parameters of CTV and no statistically significant difference was found in the dosimetric parameters of other organs-at-risk. When the setup errors in left-right and anterior-posterior directions were 3 mm, Gamma passing rate was less than 95%. Conclusion Setup errors have great dosimetric effects on PTV, spinal cord and unaffected breast. The dose distribution is more affected by the setup errors from left-right and anterior-posterior directions compared with superior-inferior direction. When the setup error is larger than 3 mm, it should be corrected.
Last Update: 2021-07-26