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Monte Carlo study of TLD measurements in air cavities

Haraldsson, P; Knöös, Tommy LU ; Nystrom, H and Engstrom, Per LU (2003) In Physics in Medicine and Biology 48(18). p.253-259
Abstract
Thermoluminescent dosimeters (TLDs) are used for verification of the delivered dose during IMRT treatment of head and neck carcinomas. The TLDs are put into a plastic tube, which is placed in the nasal cavities through the treated volume. In this study, the dose distribution to a phantom having a cylindrical air cavity containing a tube was calculated by Monte Carlo methods and the results were compared with data from a treatment planning system (TPS) to evaluate the accuracy of the TLD measurements. The phantom was defined in the DOSXYZnrc Monte Carlo code and calculations were performed with 6 MV fields, with the TLD tube placed at different positions within the cylindrical air cavity. A similar phantom was defined in the pencil beam... (More)
Thermoluminescent dosimeters (TLDs) are used for verification of the delivered dose during IMRT treatment of head and neck carcinomas. The TLDs are put into a plastic tube, which is placed in the nasal cavities through the treated volume. In this study, the dose distribution to a phantom having a cylindrical air cavity containing a tube was calculated by Monte Carlo methods and the results were compared with data from a treatment planning system (TPS) to evaluate the accuracy of the TLD measurements. The phantom was defined in the DOSXYZnrc Monte Carlo code and calculations were performed with 6 MV fields, with the TLD tube placed at different positions within the cylindrical air cavity. A similar phantom was defined in the pencil beam based TPS. Differences between the Monte Carlo and the TPS calculations of the absorbed dose to the TLD tube were found to be small for an open symmetrical field. For a half-beam field through the air cavity, there was a larger discrepancy. Furthermore, dose profiles through the cylindrical air cavity show, as expected, that the treatment planning system overestimates the absorbed dose in the air cavity. This study shows that when using an open symmetrical field, Monte Carlo calculations of absorbed doses to a TLD tube in a cylindrical air cavity give results comparable to a pencil beam based treatment planning system. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
in
Physics in Medicine and Biology
volume
48
issue
18
pages
253 - 259
publisher
IOP Publishing
external identifiers
  • pmid:14529213
  • wos:000185973500010
  • scopus:0141559028
ISSN
1361-6560
DOI
language
English
LU publication?
no
id
a8efb3c7-7c08-42b6-a95a-874505cf5705 (old id 298273)
date added to LUP
2007-09-03 15:14:05
date last changed
2018-05-29 12:11:13
@article{a8efb3c7-7c08-42b6-a95a-874505cf5705,
  abstract     = {Thermoluminescent dosimeters (TLDs) are used for verification of the delivered dose during IMRT treatment of head and neck carcinomas. The TLDs are put into a plastic tube, which is placed in the nasal cavities through the treated volume. In this study, the dose distribution to a phantom having a cylindrical air cavity containing a tube was calculated by Monte Carlo methods and the results were compared with data from a treatment planning system (TPS) to evaluate the accuracy of the TLD measurements. The phantom was defined in the DOSXYZnrc Monte Carlo code and calculations were performed with 6 MV fields, with the TLD tube placed at different positions within the cylindrical air cavity. A similar phantom was defined in the pencil beam based TPS. Differences between the Monte Carlo and the TPS calculations of the absorbed dose to the TLD tube were found to be small for an open symmetrical field. For a half-beam field through the air cavity, there was a larger discrepancy. Furthermore, dose profiles through the cylindrical air cavity show, as expected, that the treatment planning system overestimates the absorbed dose in the air cavity. This study shows that when using an open symmetrical field, Monte Carlo calculations of absorbed doses to a TLD tube in a cylindrical air cavity give results comparable to a pencil beam based treatment planning system.},
  author       = {Haraldsson, P and Knöös, Tommy and Nystrom, H and Engstrom, Per},
  issn         = {1361-6560},
  language     = {eng},
  number       = {18},
  pages        = {253--259},
  publisher    = {IOP Publishing},
  series       = {Physics in Medicine and Biology},
  title        = {Monte Carlo study of TLD measurements in air cavities},
  url          = {http://dx.doi.org/},
  volume       = {48},
  year         = {2003},
}