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Geometry optimisation of graphite energy degrader for proton therapy
Introduction: Cyclotron-based proton therapy facilities use an energy degrader of variable thickness to deliver beams of the different energies required by a patient treatment plan; scattering and straggling in the degrader give rise to an inherent emittance increase and subsequent particle loss in...
Autores principales: | , , , |
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Lenguaje: | eng |
Publicado: |
2020
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Materias: | |
Acceso en línea: | https://dx.doi.org/10.1016/j.ejmp.2020.06.023 http://cds.cern.ch/record/2801426 |
_version_ | 1780972695492493312 |
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author | Oponowicz, E Owen, H L Psoroulas, S Meer, D |
author_facet | Oponowicz, E Owen, H L Psoroulas, S Meer, D |
author_sort | Oponowicz, E |
collection | CERN |
description | Introduction: Cyclotron-based proton therapy facilities use an energy degrader of variable thickness to deliver beams of the different energies required by a patient treatment plan; scattering and straggling in the degrader give rise to an inherent emittance increase and subsequent particle loss in the downstream energy-selection system (ESS). Here we study alternative graphite degrader geometries and examine with Monte-Carlo simulations the induced emittance growth and consequent particle transmission.
Methods: We examined the conventional multiple-wedge degrader used in the Paul Scherrer Institute PROSCAN proton therapy system, the equivalent parallel-sided degrader, and a single block degrader of equivalent thickness. G4Beamline Monte-Carlo tracking of protons was benchmarked against measurements of the existing degrader for proton energies from 75 to 230 MeV, and used to validate simulations of the alternative geometries.
Results: Using a careful calculation of the beam emittance growth, we determined that a single-block degrader placed close to the collimators of the ESS is expected to deliver significantly larger transmission, up to 17% larger at 150 MeV. At the lowest deliverable of 75 MeV there is still a clear improvement in beam transmission.
Conclusions: Whilst dose rates are not presently limited on the PROSCAN system at higher energies, a single-block degrader offers the ability to access either lower energies for treatment or a larger dose rate at 75 MeV in case transmission optimisation is desired. Single-block degraders should be considered for the delivery of low-energy protons from a cyclotron-based particle therapy system. |
id | cern-2801426 |
institution | Organización Europea para la Investigación Nuclear |
language | eng |
publishDate | 2020 |
record_format | invenio |
spelling | cern-28014262022-10-31T15:31:04Zdoi:10.1016/j.ejmp.2020.06.023http://cds.cern.ch/record/2801426engOponowicz, EOwen, H LPsoroulas, SMeer, DGeometry optimisation of graphite energy degrader for proton therapyHealth Physics and Radiation EffectsIntroduction: Cyclotron-based proton therapy facilities use an energy degrader of variable thickness to deliver beams of the different energies required by a patient treatment plan; scattering and straggling in the degrader give rise to an inherent emittance increase and subsequent particle loss in the downstream energy-selection system (ESS). Here we study alternative graphite degrader geometries and examine with Monte-Carlo simulations the induced emittance growth and consequent particle transmission. Methods: We examined the conventional multiple-wedge degrader used in the Paul Scherrer Institute PROSCAN proton therapy system, the equivalent parallel-sided degrader, and a single block degrader of equivalent thickness. G4Beamline Monte-Carlo tracking of protons was benchmarked against measurements of the existing degrader for proton energies from 75 to 230 MeV, and used to validate simulations of the alternative geometries. Results: Using a careful calculation of the beam emittance growth, we determined that a single-block degrader placed close to the collimators of the ESS is expected to deliver significantly larger transmission, up to 17% larger at 150 MeV. At the lowest deliverable of 75 MeV there is still a clear improvement in beam transmission. Conclusions: Whilst dose rates are not presently limited on the PROSCAN system at higher energies, a single-block degrader offers the ability to access either lower energies for treatment or a larger dose rate at 75 MeV in case transmission optimisation is desired. Single-block degraders should be considered for the delivery of low-energy protons from a cyclotron-based particle therapy system.oai:cds.cern.ch:28014262020 |
spellingShingle | Health Physics and Radiation Effects Oponowicz, E Owen, H L Psoroulas, S Meer, D Geometry optimisation of graphite energy degrader for proton therapy |
title | Geometry optimisation of graphite energy degrader for proton therapy |
title_full | Geometry optimisation of graphite energy degrader for proton therapy |
title_fullStr | Geometry optimisation of graphite energy degrader for proton therapy |
title_full_unstemmed | Geometry optimisation of graphite energy degrader for proton therapy |
title_short | Geometry optimisation of graphite energy degrader for proton therapy |
title_sort | geometry optimisation of graphite energy degrader for proton therapy |
topic | Health Physics and Radiation Effects |
url | https://dx.doi.org/10.1016/j.ejmp.2020.06.023 http://cds.cern.ch/record/2801426 |
work_keys_str_mv | AT oponowicze geometryoptimisationofgraphiteenergydegraderforprotontherapy AT owenhl geometryoptimisationofgraphiteenergydegraderforprotontherapy AT psoroulass geometryoptimisationofgraphiteenergydegraderforprotontherapy AT meerd geometryoptimisationofgraphiteenergydegraderforprotontherapy |