A Novel Beam Optics Concept to Maximize the Transmission Through Cyclotron-based Proton Therapy Gantries
Abstract
Most of the conventional beam optics of cyclotron-based proton gantries were designed to provide point-to-point focus in both planes with an imaging factor between 1 and 2 from the entrance of the gantry to the patient. This means that a small beam size at the gantry entrance is required to achieve the required small beam size at the patient. Due to the typically used beam emittance, this in turn results in large beam divergence at the gantry entrance, increasing the possibility of beam losses along the gantry as the beam envelope gets close to the apertures. To maximize transmission through the gantry, we propose a novel beam optics concept using 3:1 imaging. It reduces the beam divergence at the gantry entrance by factor 3 while still achieving a small beam size at the patient. The beam envelope is better controlled and keeps clear of the apertures compared to the 1:1 or 1:2 imaging beam envelope. For PSI Gantry 2, the novel 3:1 imaging beam optics increase the proton beam transmission for lower energies by 40% compare to 1:1 imaging beam optics. The usage of small imaging factors can help to maximize transmission for different gantry lattices, thus reducing treatment times. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000507001Publication status
publishedExternal links
Book title
Proceedings of the 12th International Particle Accelerator Conference (IPAC 2021)Pages / Article No.
Publisher
JACoW PublishingEvent
Subject
Accelerator Physics; MC8: Applications of Accelerators, Technology Transfer, Industrial Relations and Outreach; Proton therapy; Gantry; Cyclotron based proton therapy facility; Beam OpticsOrganisational unit
02010 - Dep. Physik / Dep. of Physics
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