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RISS 인기검색어
- 검색키워드
- 저자 : Zheng Jinxing (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
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Wang, Ming,Zheng, Jinxing,Song, Yuntao,Li, Ming,Zeng, Xianhu Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.9
For proton pencil beam scanning (PBS) technology, the accuracy of the dose distribution in a patient is sensitive to the properties of the incident beam. However, mechanical deformation of the proton therapy facility may occur, and this could be an important factor affecting the proton dose distribution in patients. In this paper, we investigated the effect of deformation on an SC200 proton facility's beam isocenter properties. First, mechanical deformation of the PBS nozzle, L-shape plate, and gantry were simulated using a Finite Element code, ANSYS. Then, the impact of the mechanical deformation on the beam's isocenter properties was evaluated using empirical formulas. In addition, we considered the simplest case that could affect the properties of the incident beam (i.e. if only the bending magnet (BG3) has an error in its mounting alignment), and the effect of the beam optics offset on the isocenter characteristics was evaluated. The results showed that the deformation of the beam position in the X and Y direction was less than 0.27 mm, which meets the structural design requirements. Compared to the mechanical deformation of the L-shape plate, the deformation of the gantry had more influence on the beam's isocenter properties. When the error in the mounting alignment of the BG3 is equal to or more than 0.3 mm, the beam deformation at the isocenter exceeds the maximum accepted deformation limits. Generally speaking, for the current design of the SC200 scanning beam delivery system, the effects of mechanical deformation meet the maximum accepted beam deformation limits. In order to further study the effect of the incident beam optics on the isocenter properties, a fine-scale Monte Carlo model including factors relating to the PBS nozzle and the BG3 should be developed in future research.
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Investigating the effects of a range shifter on skin dose in proton therapy
Wang Ming,Zhang Lei,Zheng Jinxing,Li Guodong,Dai Wei,Dong Lang 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.1
Proton treatment may deliver a larger dose to a patient’s skin than traditional photon therapy, especially when a range shifter (RS) is inserted in the beam path. This study investigated the effects of an RS on skin dose while considering RS with different thicknesses, airgaps and materials. First, the physical model of the scanning nozzle with RS was established in the TOol for PArticle Simulation (TOPAS) code, and the effects of the RS on the skin dose were studied. Second, the variations in the skin dose and isocenter beam size were examined by reducing the air gap. Finally, the effects of different RS materials, such as polymethylmethacrylate (PMMA), Lexan, polyethylene and polystyrene, on the skin dose were analysed. The results demonstrated that the current RS design had a negligible effect on the skin dose, whereas the RS significantly impacted the isocenter beam size. The skin dose was increased considerably when the RS was placed close to the phantom. Moreover, the magnitude of the increase was related to the thickness of the inserted RS. Meanwhile, the results also revealed that the secondary proton primarily contributed to the increased skin dose.
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