Application of Gafchromic EBT3 film in the verification of TomoTherapy plan(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2018年第11期
- Page:
- 1257-1260
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Application of Gafchromic EBT3 film in the verification of TomoTherapy plan
- Author(s):
- CAI Hanfei1; 2; FANG Meifang1; XU Lu1; LIANG Baohui2; CAO Lu1; GE Wenjie1
- 1. Department of Radiation Oncology, the First Affiliated Hospital of Bengbu Medical College, Bengbu 233004, China; 2. Department of Medical Imaging, Bengbu Medical College, Bengbu 233030, China
- Keywords:
- ; Keywords: Gafchromic EBT3 film; TomoTherapy; plan verification; Gamma index analysis
- PACS:
- R812
- DOI:
- DOI:10.3969/j.issn.1005-202X.2018.11.004
- Abstract:
- Abstract: Objective To evaluate the reliability of applying Gafchromic EBT3 film-based dosimetry system for the verification of TomoTherapy plan, and to validate the correct usage of the system. Methods The film dosimetry system is composed of Gafchromic EBT3 film and Vidar DosimetryPro Advantage Red scanner. The most important characteristics of the system were investigated to determine the main influencing factors. The system was used to verify TomoTherapy plan, and the comparison of the calculated and measured dose distributions was performed using Gamma index analysis. Results The transmittance changed with time obviously after irradiation until about 4 hours later when the coloration was nearly saturated. The largest difference of scan values within 4 hours was up to 11.6%. The relative standard deviation of the repeatability of scanner was less than 0.5%. The differences of scan values between film in face-up and face-down positions were less than 0.6%, while the largest difference of scan values between landscape and portrait orientations was up to 7.0%. The Gamma analysis with a criterion of 3%/3 mm showed that the average passing rates of landscape and portrait orientations were 96.5%±2.9% and 95.7%±3.6%, respectively. Analysis of variance showed that there is no statistical difference between both orientations (a=0.05). Conclusion When using a film dosimetry system as discussed in this research, the film should be placed in the center of scanning area, and verification film and calibration film should be maintained at the same scan direction. By directly establishing one-to-one correspondence between the scan values and the absorbed doses of film, it is easy and feasible to convert the scan values of the verification film into absorbed doses.
Last Update: 2018-11-22