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Título:
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Fast optimized Monte Carlo phase-space generation and dose prediction for low energy x-ray intra-operative radiation therapy
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Autores:
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Vidal, Marie ;
Ibáñez García, Paula Beatriz ;
Guerra, P. ;
Valdivieso Casique, M. F. ;
Rodrigues, R. ;
Illane, C. ;
Udías Moinelo, José Manuel
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Tipo de documento:
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texto impreso
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Editorial:
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IOP publishing ltd, 2019-04
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Dimensiones:
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application/pdf
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Nota general:
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cc_by_nc_nd
info:eu-repo/semantics/openAccess
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Idiomas:
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Palabras clave:
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Estado = Publicado
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Materia = Ciencias: Física: Física nuclear
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Tipo = Artículo
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Resumen:
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Low energy x-ray intra-operative radiation therapy (IORT) is used mostly for breast cancer treatment with spherical applicators. X-ray IORT treatment delivered during surgery (ex: INTRABEAM (R), Carl Zeiss) can benefit from accurate and fast dose prediction in a patient 3D volume. However, full Monte Carlo (MC) simulations are time-consuming and no commercial treatment planning system (TPS) was available for this treatment delivery technique. Therefore, the aim of this work is to develop a dose computation tool based on MC phase space information, which computes fast and accurate dose distributions for spherical and needle INTRABEAM (R) applicators. First, a database of monoenergetic phase-space (PHSP) files and depth dose profiles (DDPs) in water for each applicator is generated at factory and stored for on-site use. During commissioning of a given INTRABEAM (R) unit, the proposed fast and optimized phase-space (FOPS) generation process creates a phase-space at the exit of the applicator considered, by fitting the energy spectrum of the source to a combination of the monoenergetic precomputed phase-spaces, by means of a genetic algorithm, with simple experimental data of DDPs in water provided by the user. An in-house hybrid MC (HMC) algorithm which takes into account condensed history simulations of photoelectric, Rayleigh and Compton interactions for x-rays up to 1 MeV computes the dose from the optimized phase-space file. The whole process has been validated against radiochromic films in water as well as reference MC simulations performed with pen Easy in heterogeneous phantoms. From the pre-computed monoenergetic PHSP files and DDPs, building the PHSP file optimized to a particular depth-dose curve in water only takes a few minutes in a single core (i7@2.5 GHz), for all the applicators considered in this work, and this needs to be done only when the x-ray source (XRS) is replaced. Once the phase-space file is ready, the HMC code is able to compute dose distributions within 10 min. For all the applicators, more than 95% of voxels from dose distributions computed with the FOPS+hybrid code agreed within 7%-0.5 mm with both reference MC simulations and measurements. The method proposed has been fully validated and it is now implemented into radiance (GMV SA, Spain), the first commercial IORT TPS.
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En línea:
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https://eprints.ucm.es/57892/1/Ud%C3%ADasJM24pospr.%2BCC.pdf
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