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Title: Monte Carlo simulation estimates of neutron doses to critical organs of a patient undergoing 18 MV x-ray LINAC-based radiotherapy

Abstract

Absorbed photoneutron dose to patients undergoing 18 MV x-ray therapy was studied using Monte Carlo simulations based on the MCNPX code. Two separate transport simulations were conducted, one for the photoneutron contribution and another for neutron capture gamma rays. The phantom model used was of a female patient receiving a four-field pelvic box treatment. Photoneutron doses were determinate to be higher for organs and tissues located inside the treatment field, especially those closest to the patient's skin. The maximum organ equivalent dose per x-ray treatment dose achieved within each treatment port was 719 {mu}Sv/Gy to the rectum (180 deg. field), 190 {mu}Sv/Gy to the intestine wall (0 deg. field), 51 {mu}Sv/Gy to the colon wall (90 deg. field), and 45 {mu}Sv/Gy to the skin (270 deg. field). The maximum neutron equivalent dose per x-ray treatment dose received by organs outside the treatment field was 65 {mu}Sv/Gy to the skin in the antero-posterior field. A mean value of 5{+-}2 {mu}Sv/Gy was obtained for organs distant from the treatment field. Distant organ neutron equivalent doses are all of the same order of magnitude and constitute a good estimate of deep organ neutron equivalent doses. Using the risk assessment method of the ICRP-60more » report, the greatest likelihood of fatal secondary cancer for a 70 Gy dose is estimated to be 0.02% for the pelvic postero-anterior field, the rectum being the organ representing the maximum contribution of 0.011%.« less

Authors:
; ; ;  [1]
  1. Hospital Universitario Rio Hortega de Valladolid, Valladolid, (Spain)
Publication Date:
OSTI Identifier:
20726857
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 32; Journal Issue: 12; Other Information: DOI: 10.1118/1.2122547; (c) 2005 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; COMPUTERIZED SIMULATION; CRITICAL ORGANS; ICRP; LINEAR ACCELERATORS; MONTE CARLO METHOD; NEOPLASMS; NEUTRON CAPTURE THERAPY; NEUTRON DOSIMETRY; NEUTRON REACTIONS; NEUTRON SOURCES; NEUTRONS; PATIENTS; PHANTOMS; RADIATION DOSES; RADIOTHERAPY; RECTUM; RISK ASSESSMENT; SKIN; X RADIATION

Citation Formats

Barquero, R, Edwards, T M, Iniguez, M P, Vega-Carrillo, H R, Departimento Fisica Teorica, Atomica, Molecular y Nuclear, Universidad de Valladolid, Valladolid, and UAs: Estudios Nucleares, Ingenieria Electrica, Matematicas, Apdo. Postal 336, 98000 Zacatecas, Zac. Monte Carlo simulation estimates of neutron doses to critical organs of a patient undergoing 18 MV x-ray LINAC-based radiotherapy. United States: N. p., 2005. Web. doi:10.1118/1.2122547.
Barquero, R, Edwards, T M, Iniguez, M P, Vega-Carrillo, H R, Departimento Fisica Teorica, Atomica, Molecular y Nuclear, Universidad de Valladolid, Valladolid, & UAs: Estudios Nucleares, Ingenieria Electrica, Matematicas, Apdo. Postal 336, 98000 Zacatecas, Zac. Monte Carlo simulation estimates of neutron doses to critical organs of a patient undergoing 18 MV x-ray LINAC-based radiotherapy. United States. https://doi.org/10.1118/1.2122547
Barquero, R, Edwards, T M, Iniguez, M P, Vega-Carrillo, H R, Departimento Fisica Teorica, Atomica, Molecular y Nuclear, Universidad de Valladolid, Valladolid, and UAs: Estudios Nucleares, Ingenieria Electrica, Matematicas, Apdo. Postal 336, 98000 Zacatecas, Zac. 2005. "Monte Carlo simulation estimates of neutron doses to critical organs of a patient undergoing 18 MV x-ray LINAC-based radiotherapy". United States. https://doi.org/10.1118/1.2122547.
@article{osti_20726857,
title = {Monte Carlo simulation estimates of neutron doses to critical organs of a patient undergoing 18 MV x-ray LINAC-based radiotherapy},
author = {Barquero, R and Edwards, T M and Iniguez, M P and Vega-Carrillo, H R and Departimento Fisica Teorica, Atomica, Molecular y Nuclear, Universidad de Valladolid, Valladolid and UAs: Estudios Nucleares, Ingenieria Electrica, Matematicas, Apdo. Postal 336, 98000 Zacatecas, Zac.},
abstractNote = {Absorbed photoneutron dose to patients undergoing 18 MV x-ray therapy was studied using Monte Carlo simulations based on the MCNPX code. Two separate transport simulations were conducted, one for the photoneutron contribution and another for neutron capture gamma rays. The phantom model used was of a female patient receiving a four-field pelvic box treatment. Photoneutron doses were determinate to be higher for organs and tissues located inside the treatment field, especially those closest to the patient's skin. The maximum organ equivalent dose per x-ray treatment dose achieved within each treatment port was 719 {mu}Sv/Gy to the rectum (180 deg. field), 190 {mu}Sv/Gy to the intestine wall (0 deg. field), 51 {mu}Sv/Gy to the colon wall (90 deg. field), and 45 {mu}Sv/Gy to the skin (270 deg. field). The maximum neutron equivalent dose per x-ray treatment dose received by organs outside the treatment field was 65 {mu}Sv/Gy to the skin in the antero-posterior field. A mean value of 5{+-}2 {mu}Sv/Gy was obtained for organs distant from the treatment field. Distant organ neutron equivalent doses are all of the same order of magnitude and constitute a good estimate of deep organ neutron equivalent doses. Using the risk assessment method of the ICRP-60 report, the greatest likelihood of fatal secondary cancer for a 70 Gy dose is estimated to be 0.02% for the pelvic postero-anterior field, the rectum being the organ representing the maximum contribution of 0.011%.},
doi = {10.1118/1.2122547},
url = {https://www.osti.gov/biblio/20726857}, journal = {Medical Physics},
issn = {0094-2405},
number = 12,
volume = 32,
place = {United States},
year = {2005},
month = {12}
}