New Gantry Beam Optics Solution for Minimising Treatment Time in Cyclotron-based Proton Therapy Facilities
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Datum
2021-06Typ
- Conference Poster
ETH Bibliographie
yes
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Abstract
Treatment delivery time in proton therapy depends on beam-on time and the time required to change energy layers and/or lateral position. For cyclotron-based facilities, low energy beams (100-70 MeV) are inefficiently transported through beamlines due to their large emittance after the degrader (~400 pi*mm*mrad 2-sigma emittance), whereas the beamline and Gantry can only transport small emittances (e.g. 30 pi*mm*mrad for PSI Gantry 2) resulting in a low dose rate at the patient and increased beam-on time.
In this work, we aim to maximize the emittance transported through the gantry for low energy beams. By choosing a small divergence, but large beam size, at the gantry entrance, it is possible to transport higher emittances through the gantry without compromising transmission. Additionally, in order to retrieve small beam sizes at the patient, we propose a 2:1 imaging of the gantry beam optics between the gantry coupling point and the patient.
This concept has been experimentally validated on Gantry 2 at PSI. A beam with an emittance of 90 pi*mm*mrad and ~60% transmission was transported through the gantry. As we are transporting only a narrow part of the large Gaussian beam after the degrader, this 3 times higher emittance corresponds to ~3 times more transported particles. With this, treatment times for example cases (lung and liver) have been estimated to reduce by a factor of 2 to 3. Such a beam optic could therefore have substantial potential for reducing treatment times, and be of particular advantage for the treatment of moving targets. Mehr anzeigen
Persistenter Link
https://doi.org/10.3929/ethz-b-000497120Publikationsstatus
publishedVerlag
ETH Zurich, Department of PhysicsKonferenz
Thema
proton therapy; Particle therapy; Gantry; Cyclotron based proton therapy facility; Spot Scanning; Pencil beam scanning proton therapy; high dose rates; Ultrafast treatmentOrganisationseinheit
02010 - Dep. Physik / Dep. of Physics
ETH Bibliographie
yes
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