Tracking and evaluation of actual dose distribution errors in radiotherapy for locally advanced esophageal squamous cell carcinoma(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2021年第12期
- Page:
- 1453-1459
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Tracking and evaluation of actual dose distribution errors in radiotherapy for locally advanced esophageal squamous cell carcinoma
- Author(s):
- LIU Yimei1; 2; PENG Yinglin2; QIU Bo2; LI Qiwen2; ZHANG Jun2; LIU Hui2; DENG Xiaowu2; WU Dehua1
- 1. Department of Radiation Oncology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China 2. Sun Yat-sen University Cancer Center/State Key Laboratory of Oncology in South China/Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
- Keywords:
- Keywords: locally advanced esophageal squamous cell carcinoma adaptive radiotherapy target coverage dose deviation ratio
- PACS:
- R735.1；R815.6
- DOI:
- DOI:10.3969/j.issn.1005-202X.2021.12.001
- Abstract:
- Abstract: Objective To evaluate dosimetric changes of target areas and organs-at-risk caused by positioning error, respiratory movement and anatomical structure displacement during radiotherapy for locally advanced esophageal squamous cell carcinoma using simulated CT images obtained by repeated scanning, and to explore the demands of adaptive radiotherapy for esophageal cancer. Methods Thirteen patients with locally advanced esophageal squamous cell carcinoma were enrolled, including 7 treated with intensity-modulated radiotherapy and 6 receiving three-dimensional conformal radiotherapy. The prescribed doses to PTV1 and PTV2 were 64 Gy/32 F and 46 Gy/23F, respectively. Simulated CT scanning was repeated at the end of the 5th, 10th, 15th, 20th and 25th treatments, and the target area and organs-at-risk were delineated, and the dose profile of treatment plan was calculated in the repeated CT image. The treated dose (Dtreated) was tracked and accumulated by deformation registration method for obtaining the actual accumulated dose profile which was then compared with that in the original plan (Dplanned). Results Along with radiotherapy, the prescribed dose coverage rates of PTV1 and PTV2 were decreased accordingly, while the Dmean to lungs and the D1cc to spinal cord were increased significantly. At the end of treatment, the V95% of PTV1 and PTV2 were decreased by -2.73%±2.82% and -1.88%±1.44%, respectively (P<0.05). There were 2 cases in which the V95% of PTV1 had a decrease more than 5%, with a maximum deviation of -9.16%. The Dmean to lungs and the D1 cc to spinal cord in treatment practice were increased from (17.90±2.78) Gy and (47.04±3.21) Gy to (18.27±3.18) Gy and (49.02±3.96) Gy, respectively, increasing by 1.84%±3.83% and 4.25%±5.72%, respectively, and the difference in the D1 cc to spinal cord was statistically significant (P<0.05). The number of cases with spinal cord D1 cc deviations greater than 3% and 5% was 6 and 5, respectively. The change in the Dmean to the heart was trivial. Conclusion During radiotherapy for locally advanced esophageal squamous cell carcinoma, the prescribed dose coverage rate of target area is decreased, and the radiation doses to lungs and spinal cord are increased in more than 50% cases. Dose evaluation during the course of treatment and the implementation of adaptive radiotherapy at the end of the 10th treatment may have clinical benefits.
Last Update: 2021-12-24