Design of a large momentum acceptance proton therapy gantry utilizing AG-CCT magnets
作者机构：Huazhong Univ Sci & Technol State Key Lab Adv Electromagnet Technol Wuhan 430074 Peoples R China
出 版 物：《NUCLEAR SCIENCE AND TECHNIQUES》 (核技术（英文）)
年 卷 期：2024年第35卷第10期
页 面：1-11页
核心收录：
学科分类：07[理学] 0827[工学-核科学与技术] 070202[理学-粒子物理与原子核物理] 0702[理学-物理学]
基 金：National Natural Science Foundation of China [11975107 12205111]
主 题：Alternating-gradient canted-cosine-theta magnets Large momentum acceptance gantry Pencil beam scanning Proton therapy ENERGY DEGRADER BEAM OPTICS OPTIMIZATION
摘 要：The application of superconducting (SC) technology enables magnets to excite strong fields with small footprints, which has great potential for miniaturizing proton therapy gantries. However, the slow ramping rate of SC magnets results in a low treatment efficiency compared with normal-conducting (NC) gantries. To address this problem, this study proposes a compact proton therapy gantry design with a large momentum acceptance utilizing alternating-gradient canted-cosine-theta (AG-CCT) SC magnets. In our design, a high-transmission degrader is mounted in the middle of the gantry, and the upstream beamline employs NC magnets with small apertures. Downstream of the degrader, large-bore AG-CCT magnets with strong alternating focusing gradients are set symmetrically as a local achromat, which realizes a momentum acceptance of 20% (or 40% in the energy domain). Therefore, only three magnetic working points are required to cover a treatment energy of 70-230 MeV. Owing to the large momentum acceptance, the proton beam after the degrader can be directly delivered to the isocenter without truncating its energy spectrum, which can significantly increase the treatment efficiency but causes severe dispersion effects during pencil beam scanning. Therefore, a compensation method was introduced by tuning the normal and skewed quadrupoles during the scanning process. As a result, the new gantry not only presents a remarkable reduction in the size and weight of the facility but also shows good potential for fast treatment.
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