Comparative dosimetry of diode and diamond detectors in electron beams for intraoperative radiation therapy
Björk, Peter LU ; Knöös, Tommy LU
and Nilsson, Per
LU
(2000)
In Medical Physics
27(11).
p.2580-2588
- Abstract
- The aim of the present study is to examine the validity of using silicon semiconductor detectors in degraded electron beams with a broad energy spectrum and a wide angular distribution. A comparison is made with diamond detector measurements, which is the dosimeter considered to give the best results provided that dose rate effects are corrected for. Two-dimensional relative absorbed dose distributions in electron beams (6-20 MeV) for intraoperative radiation therapy (IORT) are measured in a water phantom. To quantify deviations between the detectors, a dose comparison tool that simultaneously examines the dose difference and distance to agreement (DTA) is used to evaluate the results in low- and high-dose gradient regions, respectively.... (More)
- The aim of the present study is to examine the validity of using silicon semiconductor detectors in degraded electron beams with a broad energy spectrum and a wide angular distribution. A comparison is made with diamond detector measurements, which is the dosimeter considered to give the best results provided that dose rate effects are corrected for. Two-dimensional relative absorbed dose distributions in electron beams (6-20 MeV) for intraoperative radiation therapy (IORT) are measured in a water phantom. To quantify deviations between the detectors, a dose comparison tool that simultaneously examines the dose difference and distance to agreement (DTA) is used to evaluate the results in low- and high-dose gradient regions, respectively. Uncertainties of the experimental measurement setup (+/- 1% and +/- 0.5 mm) are taken into account by calculating a composite distribution that fails this dose-difference and DTA acceptance limit. Thus, the resulting area of disagreement should be related to differences in detector performance. The dose distributions obtained with the diode are generally in very good agreement with diamond detector measurements. The buildup region and the dose falloff region show good agreement with increasing electron energy, while the region outside the radiation field close to the water surface shows an increased difference with energy. The small discrepancies in the composite distributions are due to several factors: (a) variation of the silicon-to-water collision stopping-power ratio with electron energy, (b) a more pronounced directional dependence for diodes than for diamonds, and (c) variation of the electron fluence perturbation correction factor with depth. For all investigated treatment cones and energies, the deviation is within dose-difference and DTA acceptance criteria of +/- 3% and +/- 1 mm, respectively. Therefore, p-type silicon diodes are well suited, in the sense that they give results in close agreement with diamond detectors, for practical measurements of relative absorbed dose distributions in degraded electron beams used for IORT. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/1116899
- author
- Björk, Peter
LU
; Knöös, Tommy
LU
and Nilsson, Per
LU
- organization
- publishing date
- 2000
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- diamond detector, silicon diode, intraoperative radiation therapy, electron beam dosimetry, dose distribution analysis
- in
- Medical Physics
- volume
- 27
- issue
- 11
- pages
- 2580 - 2588
- publisher
- American Association of Physicists in Medicine
- external identifiers
-
- pmid:11128310
- scopus:0033679098
- ISSN
- 0094-2405
- DOI
- 10.1118/1.1315317
- language
- English
- LU publication?
- yes
- id
- 5b608da3-c6c0-4877-9416-e4d016679392 (old id 1116899)
- date added to LUP
- 2016-04-01 16:40:48
- date last changed
- 2022-01-28 21:23:07
@article{5b608da3-c6c0-4877-9416-e4d016679392,
abstract = {{The aim of the present study is to examine the validity of using silicon semiconductor detectors in degraded electron beams with a broad energy spectrum and a wide angular distribution. A comparison is made with diamond detector measurements, which is the dosimeter considered to give the best results provided that dose rate effects are corrected for. Two-dimensional relative absorbed dose distributions in electron beams (6-20 MeV) for intraoperative radiation therapy (IORT) are measured in a water phantom. To quantify deviations between the detectors, a dose comparison tool that simultaneously examines the dose difference and distance to agreement (DTA) is used to evaluate the results in low- and high-dose gradient regions, respectively. Uncertainties of the experimental measurement setup (+/- 1% and +/- 0.5 mm) are taken into account by calculating a composite distribution that fails this dose-difference and DTA acceptance limit. Thus, the resulting area of disagreement should be related to differences in detector performance. The dose distributions obtained with the diode are generally in very good agreement with diamond detector measurements. The buildup region and the dose falloff region show good agreement with increasing electron energy, while the region outside the radiation field close to the water surface shows an increased difference with energy. The small discrepancies in the composite distributions are due to several factors: (a) variation of the silicon-to-water collision stopping-power ratio with electron energy, (b) a more pronounced directional dependence for diodes than for diamonds, and (c) variation of the electron fluence perturbation correction factor with depth. For all investigated treatment cones and energies, the deviation is within dose-difference and DTA acceptance criteria of +/- 3% and +/- 1 mm, respectively. Therefore, p-type silicon diodes are well suited, in the sense that they give results in close agreement with diamond detectors, for practical measurements of relative absorbed dose distributions in degraded electron beams used for IORT.}},
author = {{Björk, Peter and Knöös, Tommy and Nilsson, Per}},
issn = {{0094-2405}},
keywords = {{diamond detector; silicon diode; intraoperative radiation therapy; electron beam dosimetry; dose distribution analysis}},
language = {{eng}},
number = {{11}},
pages = {{2580--2588}},
publisher = {{American Association of Physicists in Medicine}},
series = {{Medical Physics}},
title = {{Comparative dosimetry of diode and diamond detectors in electron beams for intraoperative radiation therapy}},
url = {{http://dx.doi.org/10.1118/1.1315317}},
doi = {{10.1118/1.1315317}},
volume = {{27}},
year = {{2000}},
}