TY - JOUR
T1 - Peripheral Organ Equivalent Dose Estimation Procedure in Proton Therapy
AU - Domingo, Carles
AU - Lagares, Juan Ignacio
AU - Romero-Expósito, Maite
AU - Sánchez-Nieto, Beatriz
AU - Nieto-Camero, Jaime J.
AU - Terrón, Jose Antonio
AU - Irazola, Leticia
AU - Dasu, Alexandru
AU - Sánchez-Doblado, Francisco
N1 - Publisher Copyright:
Copyright © 2022 Domingo, Lagares, Romero-Expósito, Sánchez-Nieto, Nieto-Camero, Terrón, Irazola, Dasu and Sánchez-Doblado.
PY - 2022/5/25
Y1 - 2022/5/25
N2 - 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.
AB - 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.
KW - neutron and photon dose
KW - neutron spectrometry
KW - peripheral organ dose
KW - proton therapy
KW - secondary cancer risk
UR - http://www.scopus.com/inward/record.url?scp=85132128494&partnerID=8YFLogxK
U2 - 10.3389/fonc.2022.882476
DO - 10.3389/fonc.2022.882476
M3 - Article
C2 - 35692801
AN - SCOPUS:85132128494
SN - 2234-943X
VL - 12
JO - Frontiers in Oncology
JF - Frontiers in Oncology
M1 - 882476
ER -