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Title: Monte Carlo simulations of dose near a nonradioactive gold seed

Abstract

The relative doses and hot/cold spot positions around a non-radioactive gold seed, irradiated by a 6 or 18 MV photon beam in water, were calculated using Monte Carlo simulation. Phase space files of 6 and 18 MV photon beams with a field size of 1x1 cm{sup 2} were generated by a Varian 21 EX linear accelerator using the EGSnrc and BEAMnrc code. The seed (1.2x1.2x3.2 mm{sup 3}) was positioned at the isocenter in a water phantom (20x20x20 cm{sup 2}) with source-to-axis distance=100 cm. For the single beam geometry, the relative doses (normalized to the dose at 5 mm distance above the isocenter) at the upstream seed surface were calculated to be 1.64 and 1.56 for the 6 and 18 MV beams respectively when the central beam axis (CAX) is parallel to the width of the seed. These doses were slightly higher than those (1.58 and 1.52 for 6 and 18 MV beams respectively) calculated when the CAX is perpendicular to the width of the seed. Compared to the relative dose profiles with the same beam geometry without the seed in the water phantom, the presence of the seed affects the dose distribution at about 3 mm distance beyond both themore » upstream and downstream seed surface. For a pair of opposing beams with equal and unequal beam weight, the hot and cold spots of both opposing beams were mixed. For a 360 degree photon arc around the longitudinal axis of the seed, the relative dose profile along the width of the seed was similar to that of the opposing beam pair, except the former geometry has a larger dose gradient near the seed surface. In this study, selected results from our simulation were compared to previous measurements using film dosimetry.« less

Authors:
;  [1];  [2]
  1. Department of Radiation Oncology, University of Toronto and Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, ON N2G 1G3 (Canada) and Department of Physics, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada)
  2. (Canada)
Publication Date:
OSTI Identifier:
20853830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 33; Journal Issue: 12; Other Information: DOI: 10.1118/1.2388573; (c) 2006 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; COMPUTERIZED SIMULATION; FILM DOSIMETRY; GOLD; IRRADIATION; LINEAR ACCELERATORS; MONTE CARLO METHOD; PHANTOMS; PHASE SPACE; PHOTON BEAMS; PROSTATE; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIOTHERAPY

Citation Formats

Chow, James C. L., Grigorov, Grigor N., and Medical Physics Department, Grand River Regional Cancer Center, Grand River Hospital, 835 King Street West, Kitchener, ON N2G 1G3. Monte Carlo simulations of dose near a nonradioactive gold seed. United States: N. p., 2006. Web. doi:10.1118/1.2388573.
Chow, James C. L., Grigorov, Grigor N., & Medical Physics Department, Grand River Regional Cancer Center, Grand River Hospital, 835 King Street West, Kitchener, ON N2G 1G3. Monte Carlo simulations of dose near a nonradioactive gold seed. United States. doi:10.1118/1.2388573.
Chow, James C. L., Grigorov, Grigor N., and Medical Physics Department, Grand River Regional Cancer Center, Grand River Hospital, 835 King Street West, Kitchener, ON N2G 1G3. Fri . "Monte Carlo simulations of dose near a nonradioactive gold seed". United States. doi:10.1118/1.2388573.
@article{osti_20853830,
title = {Monte Carlo simulations of dose near a nonradioactive gold seed},
author = {Chow, James C. L. and Grigorov, Grigor N. and Medical Physics Department, Grand River Regional Cancer Center, Grand River Hospital, 835 King Street West, Kitchener, ON N2G 1G3},
abstractNote = {The relative doses and hot/cold spot positions around a non-radioactive gold seed, irradiated by a 6 or 18 MV photon beam in water, were calculated using Monte Carlo simulation. Phase space files of 6 and 18 MV photon beams with a field size of 1x1 cm{sup 2} were generated by a Varian 21 EX linear accelerator using the EGSnrc and BEAMnrc code. The seed (1.2x1.2x3.2 mm{sup 3}) was positioned at the isocenter in a water phantom (20x20x20 cm{sup 2}) with source-to-axis distance=100 cm. For the single beam geometry, the relative doses (normalized to the dose at 5 mm distance above the isocenter) at the upstream seed surface were calculated to be 1.64 and 1.56 for the 6 and 18 MV beams respectively when the central beam axis (CAX) is parallel to the width of the seed. These doses were slightly higher than those (1.58 and 1.52 for 6 and 18 MV beams respectively) calculated when the CAX is perpendicular to the width of the seed. Compared to the relative dose profiles with the same beam geometry without the seed in the water phantom, the presence of the seed affects the dose distribution at about 3 mm distance beyond both the upstream and downstream seed surface. For a pair of opposing beams with equal and unequal beam weight, the hot and cold spots of both opposing beams were mixed. For a 360 degree photon arc around the longitudinal axis of the seed, the relative dose profile along the width of the seed was similar to that of the opposing beam pair, except the former geometry has a larger dose gradient near the seed surface. In this study, selected results from our simulation were compared to previous measurements using film dosimetry.},
doi = {10.1118/1.2388573},
journal = {Medical Physics},
number = 12,
volume = 33,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}