Peripheral Organ Equivalent Dose Estimation Procedure in Proton Therapy
Domingo, Carles (Universitat Autònoma de Barcelona. Departament de Física)
Lagares, Juan Ignacio (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (Espanya))
Romero-Expósito, Maite (The Skandion Clinic)
Sánchez-Nieto, Beatriz (Pontificia Universidad Católica de Chile. Instituto de Física)
Nieto-Camero, Jaime J. (iThemba Labs)
Terrón, Jose Antonio (Hospital Universitario Virgen Macarena (Sevilla, Andalusia))
Irazola, Leticia (Clínica Universidad de Navarra. Servicio de Radiofísica y Protección Radiológic)
Dasu, Alexandru (Uppsala University. Department of Immunology, Genetics and Pathology)
Sánchez-Doblado, Francisco (Universidad de Sevilla. Departamento Fisiología Médica y Biofísica)

Date:	2022
Abstract:	The aim of this work is to present a reproducible methodology for the evaluation of total equivalent doses in organs during proton therapy facilities. The methodology is based on measuring the dose equivalent in representative locations inside an anthropomorphic phantom where photon and neutron dosimeters were inserted. The Monte Carlo simulation was needed for obtaining neutron energy distribution inside the phantom. The methodology was implemented for a head irradiation case in the passive proton beam of iThemba Labs (South Africa). Thermoluminescent dosimeter (TLD)-600 and TLD-700 pairs were used as dosimeters inside the phantom and GEANT code for simulations. In addition, Bonner sphere spectrometry was performed inside the treatment room to obtain the neutron spectra, some relevant neutron dosimetric quantities per treatment Gy, and a percentual distribution of neutron fluence and ambient dose equivalent in four energy groups, at two locations. The neutron spectrum at one of those locations was also simulated so that a reasonable agreement between simulation and measurement allowed a validation of the simulation. Results showed that the total out-of-field dose equivalent inside the phantom ranged from 1. 4 to 0. 28 mSv/Gy, mainly due to the neutron contribution and with a small contribution from photons, 10% on average. The order of magnitude of the equivalent dose in organs was similar, displaying a slow reduction in values as the organ is farther from the target volume. These values were in agreement with those found by other authors in other passive beam facilities under similar irradiation and measurement conditions.
Grants:	Ministerio de Economía y Competitividad TIN2015-63562-R European Commission 945196
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Peripheral organ dose ; Proton therapy ; Neutron spectrometry ; Secondary cancer risk ; Neutron and photon dose
Published in:	Frontiers in Oncology, Vol. 12 (May 2022) , art. 882476, ISSN 2234-943X

DOI: 10.3389/fonc.2022.882476
PMID: 35692801

14 p, 8.8 MB

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