Design of a large momentum acceptance proton therapy gantry utilizing AG-CCT magnets  

作　　者：Yi-Cheng Liao Xu Liu Wei Wang Zi-Yi Yang Qu-Shan Chen Bin Qin 

机构地区：[1]State Key Laboratory of Advanced Electromagnetic Technology,Huazhong University of Science and Technology,Wuhan 430074,China

出　　处：《Nuclear Science and Techniques》2024年第10期59-69,共11页核技术（英文）

基　　金：supported by the National Natural Science Foundation of China(No.11975107,12205111)。

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 Me V.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.

关 键 词：Alternating-gradient canted-cosine-theta magnets Large momentum acceptance gantry Pencil beam scanning Proton therapy 

分 类 号：TH77[机械工程—仪器科学与技术]