Effect of immobilization baseplate of thermoplastic film on the passing rate of IMRT 3D dosimetric verification and dose modification(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2020年第3期
- Page:
- 273-276
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Effect of immobilization baseplate of thermoplastic film on the passing rate of IMRT 3D dosimetric verification and dose modification
- Author(s):
- WANG Xiaochun; WANG Shouyu; HUO Xiaoqing; ZHANG Qingqin; HONG Zhenyu; LU Ping; WU Peng; LIU Bo; WANG Yingtuo; MIAO Zhanhui
- Radiation Therapy Center, the First Affiliated Hospital of Xinxiang Medical University, Weihui 453100, China
- Keywords:
- Keywords: immobilization baseplate of thermoplastic film; intensity-modulated radiotherapy; dose modification; gamma passing rate
- PACS:
- R312；R811.1
- DOI:
- DOI:10.3969/j.issn.1005-202X.2020.03.003
- Abstract:
- Abstract: Objective To analyze and evaluate the effect of an immobilization baseplate of thermoplastic film on the passing rate of intensity-modulated radiotherapy (IMRT) three-dimensional (3D) dosimetric verification, and to modify the dose. Methods Octavius 4D dosimetric verification system was used for 3D dosimetric verification. According to the proportion of the number of incident fields to the total number of fields, 60 cases of IMRT plans were divided into 6 group for the 3D dosimetric verification with couch plate alone or couch plate combined with immobilization baseplate of thermoplastic film so as to evaluate the effect of immobilization baseplate of thermoplastic film on the passing rate of IMRT 3D dosimetric verification. Dose modification was carried out in the 6th group which had the highest proportion of the number of incidence fields in all groups, and then the passing rate was compared with that before dose modification for evaluating the role of dose modification. Results Without considering immobilization baseplate, the gamma passing rates of 6 groups of IMRT plans were 98.00%, 96.87%, 96.76%, 94.82%, 95.51% and 95.32%, respectively; and after that immobilization baseplate was considered, the gamma passing rates were 98.88%, 96.46%, 95.85%, 93.12%, 93.22% and 89.07%, respectively. The corresponding P values were 0.147, 0.534, 0.406, 0.051, 0.030 (t=2.566) and 0.000 (t=5.637), respectively, and statistical differences were only found in the 5th and 6th groups. After the dose modification for immobilization baseplate in the 6th group, the average gamma passing was 94.90%, increased by 5.8%. Conclusion Immobilization baseplate of thermoplastic film has a certain effect on the passing rate of IMRT 3D dosimetric verification, and the larger proportion of the number of incident fields in IMRT plan is, the greater effect is. It is necessary to modify the dose of immobilization baseplate when making clinical plans.
Last Update: 2020-04-02