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Title: Characterization of the phantom material Virtual Water{sup TM} in high-energy photon and electron beams

Abstract

The material Virtual Water{sup TM} has been characterized in photon and electron beams. Range-scaling factors and fluence correction factors were obtained, the latter with an uncertainty of around 0.2%. This level of uncertainty means that it may be possible to perform dosimetry in a solid phantom with an accuracy approaching that of measurements in water. Two formulations of Virtual Water{sup TM} were investigated with nominally the same elemental composition but differing densities. For photon beams neither formulation showed exact water equivalence--the water/Virtual Water{sup TM} dose ratio varied with the depth of measurement with a difference of over 1% at 10 cm depth. However, by using a density (range) scaling factor very good agreement (<0.2%) between water and Virtual Water{sup TM} at all depths was obtained. In the case of electron beams a range-scaling factor was also required to match the shapes of the depth dose curves in water and Virtual Wate{sup TM}. However, there remained a difference in the measured fluence in the two phantoms after this scaling factor had been applied. For measurements around the peak of the depth-dose curve and the reference depth this difference showed some small energy dependence but was in the range 0.1%-0.4%. Perturbation measurementsmore » have indicated that small slabs of material upstream of a detector have a small (<0.1% effect) on the chamber reading but material behind the detector can have a larger effect. This has consequences for the design of experiments and in the comparison of measurements and Monte Carlo-derived values.« less

Authors:
;  [1];  [2]
  1. Ionizing Radiation Standards, Institute for National Measurement Standards, National Research Council of Canada, Ottawa (Canada)
  2. (Canada)
Publication Date:
OSTI Identifier:
20775126
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 33; Journal Issue: 4; Other Information: DOI: 10.1118/1.2174186; (c) 2006 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; ACCURACY; CORRECTIONS; DEPTH DOSE DISTRIBUTIONS; DOSIMETRY; ELECTRON BEAMS; ENERGY DEPENDENCE; MONTE CARLO METHOD; PHANTOMS; PHOTON BEAMS; PLASTICS; RADIATION DOSES; RADIOTHERAPY

Citation Formats

McEwen, M.R., Niven, D., and Department of Physics, Carleton University, Ottawa. Characterization of the phantom material Virtual Water{sup TM} in high-energy photon and electron beams. United States: N. p., 2006. Web. doi:10.1118/1.2174186.
McEwen, M.R., Niven, D., & Department of Physics, Carleton University, Ottawa. Characterization of the phantom material Virtual Water{sup TM} in high-energy photon and electron beams. United States. doi:10.1118/1.2174186.
McEwen, M.R., Niven, D., and Department of Physics, Carleton University, Ottawa. Sat . "Characterization of the phantom material Virtual Water{sup TM} in high-energy photon and electron beams". United States. doi:10.1118/1.2174186.
@article{osti_20775126,
title = {Characterization of the phantom material Virtual Water{sup TM} in high-energy photon and electron beams},
author = {McEwen, M.R. and Niven, D. and Department of Physics, Carleton University, Ottawa},
abstractNote = {The material Virtual Water{sup TM} has been characterized in photon and electron beams. Range-scaling factors and fluence correction factors were obtained, the latter with an uncertainty of around 0.2%. This level of uncertainty means that it may be possible to perform dosimetry in a solid phantom with an accuracy approaching that of measurements in water. Two formulations of Virtual Water{sup TM} were investigated with nominally the same elemental composition but differing densities. For photon beams neither formulation showed exact water equivalence--the water/Virtual Water{sup TM} dose ratio varied with the depth of measurement with a difference of over 1% at 10 cm depth. However, by using a density (range) scaling factor very good agreement (<0.2%) between water and Virtual Water{sup TM} at all depths was obtained. In the case of electron beams a range-scaling factor was also required to match the shapes of the depth dose curves in water and Virtual Wate{sup TM}. However, there remained a difference in the measured fluence in the two phantoms after this scaling factor had been applied. For measurements around the peak of the depth-dose curve and the reference depth this difference showed some small energy dependence but was in the range 0.1%-0.4%. Perturbation measurements have indicated that small slabs of material upstream of a detector have a small (<0.1% effect) on the chamber reading but material behind the detector can have a larger effect. This has consequences for the design of experiments and in the comparison of measurements and Monte Carlo-derived values.},
doi = {10.1118/1.2174186},
journal = {Medical Physics},
number = 4,
volume = 33,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
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