Photon quality correction factors for ionization chambers in an epithelial neutron beam
Munck Af Rosenschöld, P. M. LU
; Ceberg, C. P.
LU
; Giusti, V.
and Andreo, P.
(2002)
In Physics in Medicine and Biology
47(14).
p.2397-2409
- Abstract
Photon quality correction factors (kQγ) 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... (More)
Photon quality correction factors (kQγ) 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 kQγ-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 kQγ-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)
- author
- Munck Af Rosenschöld, P. M.
LU
; Ceberg, C. P.
LU
; Giusti, V.
and Andreo, P.
- publishing date
- 2002
- 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
- pmid:12171330
- ISSN
- 1361-6560
- DOI
- 10.1088/0031-9155/47/14/303
- language
- English
- LU publication?
- no
- id
- f86ff8a4-7b98-4a2f-919b-4bf6de682079 (old id 109871)
- date added to LUP
- 2016-04-01 12:03:12
- date last changed
- 2023-07-20 09:43:58
@article{f86ff8a4-7b98-4a2f-919b-4bf6de682079,
abstract = {{<p>Photon quality correction factors (k<sub>Qγ</sub>) 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 k<sub>Qγ</sub>-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 k<sub>Qγ</sub>-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.</p>}},
author = {{Munck Af Rosenschöld, P. M. and Ceberg, C. P. 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 epithelial neutron beam}},
url = {{http://dx.doi.org/10.1088/0031-9155/47/14/303}},
doi = {{10.1088/0031-9155/47/14/303}},
volume = {{47}},
year = {{2002}},
}