Effects of the carbon fiber couch of Elekta Infinity linear accelerator on radiotherapy dose(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2021年第2期
- Page:
- 157-161
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Effects of the carbon fiber couch of Elekta Infinity linear accelerator on radiotherapy dose
- Author(s):
- SONG Hongbing; PAN Jinghui; YANG Xiong; RUAN Changli; LI Xiangpan
- Department of Radiotherapy, Renmin Hospital of Wuhan University, Wuhan 430060, China
- Keywords:
- Keywords: linear accelerator carbon fiber treatment couch attenuation factor radiotherapy dose
- PACS:
- R815.6；TH774
- DOI:
- DOI:10.3969/j.issn.1005-202X.2021.02.006
- Abstract:
- Abstract: Objective To investigate the effects of the carbon fiber treatment couch of Elekta Infinity linear accelerator on radiotherapy dose. Methods Polymethyl methacrylate cylinder phantoms were put on the centers of main treatment couch, extension board and the joint area of them, separately. The gantry was rotated at different angles to beam 6 MV and 10 MV X-rays to penetrate the carbon-fiber couch, and a thimble chamber was utilized to measure the absolute dose in the cylinder phantom. The dose distribution at each angle was recorded and the X-ray attenuation factor of the treatment couch was calculated. Results At the gantry angles of 120°and 240°, the attenuation factors at the treatment couch reached 36.02% and 36.01% under 6 MV, and those at the joint area were 30.46% and 30.63% under 10 MV. The attenuation factors at the joint area and main treatment couch were close during the gantry angle between 140° and 220°, and the average value and standard deviation of their attenuation factors were 2.56%±0.49% and 2.14%±0.39% under 6 MV, and 2.55%±0.48% and 1.95%±0.41% under 10 MV. The attenuation factors at the joint area and main treatment couch were both increased when the gantry angle was increased or decreased from 180°, and reached the maximum around the gantry angles of 120°and 240°. The average value and standard deviation of the attenuation factors at extension board under 6 MV and 10 MV in the same angular intervals were 1.55%±0.24% and 1.07%±0.25%, respectively, and the largest attenuation factors were found at the gantry angles of 115° and 245°, with 4.08% and 3.97% under 6 MV, and 3.20% and 3.34% under 10 MV. Conclusion For the main part of posterior oblique field, the X-ray attenuation factors were below 3% at main treatment couch and the joint area, while it was below 2% at extension board. However, the attenuation effect reached the maximum at the gantry angles of 120° and 240°, 115° and 245°, which make the carbon fiber couch must be considered in treatment plan system. Moreover, the joint area is not suitable for clinical treatment for it dramatically affects the delivered dose at the gantry angles of 120° and 240°, and the target area should not appeared in this area.
Last Update: 2021-02-02