Numerical Simulations to Evaluate and Compare the Performances of Existing and Novel Degrader Materials for Proton Therapy

The performance of the energy degrader in terms of beam properties directly impacts the design and cost of cyclotron-based proton therapy centers. The aim of this study is to evaluate the performances of different existing and novel degrader materials. The quantitative estimate is based on detailed GEANT4 simulations that analyze the beam-matter interaction and provide a determination of the beam emittance increase and transmission. Comparisons between existing (aluminum, graphite, beryllium) and novel (boron carbide and diamond) degrader materials are provided and evaluated against semi-analytical models of multiple Coulomb scattering. The results showing a potential in emittance reduction for novel materials are presented and discussed in detail.Comment: Submitted for IPAC 2018 "light peer review

Finite element study of AC losses in the superconducting coil of the NHa C400 cyclotron

editorial reviewedThe NHa C400 is the first compact superconducting cyclotron used for carbon therapy in the world. Carbon therapy is particularly effective for treating radiation-resistant tumors, as compared to more conventional radiotherapy techniques. In this work, a 3D finite element model of the Nb-Ti coil has been developed using the open-source solver GetDP. First, an accurate representation of the DC magnetic fields, required for beam dynamics computation, is obtained. Second, analytical models of increasing complexity for hystere- sis losses in the superconducting filaments are investigated. For discussing their accuracy, a single filament model has been developed. Third, the heat loss in the Nb-Ti coils during energization of the cyclotron is evaluated based on a multi-scale approach involving the single filament model