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Photon quality correction factors for ionization chambers in an epithermal neutron beam.

Munck af Rosenschöld, Per LU ; Ceberg, Crister LU ; Giusti, V and Andreo, P (2002) In Physics in Medicine and Biology 47(14). p.2397-2409
Abstract
Photon quality correction factors (kQy) for ionization chamber photon dosimetry in an epithermal neutron beam were determined according to a modified absorbed dose to water formalism which was extended to mixed radiation fields. We have studied two commercially available ionization chambers in the epithermal neutron beam optimized for BNCT at the facility at Studsvik, Sweden. One of the chambers is nominally neutron insensitive; a magnesium-walled detector flushed with pure argon gas (denoted by Mg/Ar). The second chamber has approximately the same sensitivity for neutrons and photons; it is considered a 'tissue equivalent' detector, with A-150 walls flushed with methane-based tissue-equivalent gas (denoted by TE/TE). The kQy-factors in... (More)
Photon quality correction factors (kQy) for ionization chamber photon dosimetry in an epithermal neutron beam were determined according to a modified absorbed dose to water formalism which was extended to mixed radiation fields. We have studied two commercially available ionization chambers in the epithermal neutron beam optimized for BNCT at the facility at Studsvik, Sweden. One of the chambers is nominally neutron insensitive; a magnesium-walled detector flushed with pure argon gas (denoted by Mg/Ar). The second chamber has approximately the same sensitivity for neutrons and photons; it is considered a 'tissue equivalent' detector, with A-150 walls flushed with methane-based tissue-equivalent gas (denoted by TE/TE). The kQy-factors in epithermal neutron beams have previously been assumed to be equal to unity or estimated from measurements in clinical accelerator produced photon beams. In this work the kQy-factors have been determined from absorbed dose calculations using cavity theory together with Monte Carlo derived electron fluences obtained with the MCNP4c system for water and PMMA phantoms. The calculated quality correction factors differ substantially from unity, being in the order of 10% for the Mg/Ar detector at shallow phantom depths, and between 2 and 4% for other depths and for the TE/TE chamber. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
in
Physics in Medicine and Biology
volume
47
issue
14
pages
2397 - 2409
publisher
IOP Publishing
external identifiers
  • pmid:12171330
  • wos:000177297700003
  • scopus:0037151129
ISSN
1361-6560
DOI
10.1088/0031-9155/47/14/303
language
English
LU publication?
yes
id
f86ff8a4-7b98-4a2f-919b-4bf6de682079 (old id 109871)
alternative location
http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12171330&dopt=Abstract
date added to LUP
2007-07-20 08:21:59
date last changed
2017-01-01 04:47:31
@article{f86ff8a4-7b98-4a2f-919b-4bf6de682079,
  abstract     = {Photon quality correction factors (kQy) for ionization chamber photon dosimetry in an epithermal neutron beam were determined according to a modified absorbed dose to water formalism which was extended to mixed radiation fields. We have studied two commercially available ionization chambers in the epithermal neutron beam optimized for BNCT at the facility at Studsvik, Sweden. One of the chambers is nominally neutron insensitive; a magnesium-walled detector flushed with pure argon gas (denoted by Mg/Ar). The second chamber has approximately the same sensitivity for neutrons and photons; it is considered a 'tissue equivalent' detector, with A-150 walls flushed with methane-based tissue-equivalent gas (denoted by TE/TE). The kQy-factors in epithermal neutron beams have previously been assumed to be equal to unity or estimated from measurements in clinical accelerator produced photon beams. In this work the kQy-factors have been determined from absorbed dose calculations using cavity theory together with Monte Carlo derived electron fluences obtained with the MCNP4c system for water and PMMA phantoms. The calculated quality correction factors differ substantially from unity, being in the order of 10% for the Mg/Ar detector at shallow phantom depths, and between 2 and 4% for other depths and for the TE/TE chamber.},
  author       = {Munck af Rosenschöld, Per and Ceberg, Crister and Giusti, V and Andreo, P},
  issn         = {1361-6560},
  language     = {eng},
  number       = {14},
  pages        = {2397--2409},
  publisher    = {IOP Publishing},
  series       = {Physics in Medicine and Biology},
  title        = {Photon quality correction factors for ionization chambers in an epithermal neutron beam.},
  url          = {http://dx.doi.org/10.1088/0031-9155/47/14/303},
  volume       = {47},
  year         = {2002},
}