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Title: Radiotherapy dosimetry using a commercial OSL system

Abstract

A commercial optically stimulated luminescence (OSL) system developed for radiation protection dosimetry by Landauer, Inc., the InLight microStar reader, was tested for dosimetry procedures in radiotherapy. The system uses carbon-doped aluminum oxide, Al{sub 2}O{sub 3}:C, as a radiation detector material. Using this OSL system, a percent depth dose curve for {sup 60}Co gamma radiation was measured in solid water. Field size and SSD dependences of the detector response were also evaluated. The dose response relationship was investigated between 25 and 400 cGy. The decay of the response with time following irradiation and the energy dependence of the Al{sub 2}O{sub 3}:C OSL detectors were also measured. The results obtained using OSL dosimeters show good agreement with ionization chamber and diode measurements carried out under the same conditions. Reproducibility studies show that the response of the OSL system to repeated exposures is 2.5% (1sd), indicating a real possibility of applying the Landauer OSL commercial system for radiotherapy dosimetric procedures.

Authors:
; ; ; ;  [1];  [2];  [3];  [4]
  1. Programa de Qualidade em Radioterapia, Instituto Nacional de Cancer (INCA/MS), Rua do Resende 128 3 Andar. Centro. Rio de Janeiro, CEP: 20231-092, Rio de Janeiro (Brazil) and Nuclear Instrumentation Laboratory, COPPE/UFRJ, P.O. Box: 68509, 21941-972, Rio de Janeiro (Brazil)
  2. (IRD/CNEN), Av. Salvador Allende s/n, Rio de Janeiro, CEP: 22780-160, Rio de Janeiro (Brazil)
  3. (Canada)
  4. (Canada) and Physics Department, Carleton University, 1125 Colonel By Dr., Ottawa, Ontario K1S 5B6 (Canada)
Publication Date:
OSTI Identifier:
21120634
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 35; Journal Issue: 4; Other Information: DOI: 10.1118/1.2841940; (c) 2008 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; ALUMINIUM OXIDES; COBALT 60; DEPTH DOSE DISTRIBUTIONS; DOPED MATERIALS; DOSE-RESPONSE RELATIONSHIPS; DOSEMETERS; DOSIMETRY; ENERGY DEPENDENCE; GAMMA RADIATION; IONIZATION CHAMBERS; LUMINESCENCE; RADIATION PROTECTION; RADIOTHERAPY

Citation Formats

Viamonte, A., Rosa, L. A. R. da, Buckley, L. A., Cherpak, A., Cygler, J. E., Instituto de Radioprotecao e Dosimetria, Department of Medical Physics, Ottawa Hospital Regional Cancer Centre, 503 Smyth Rd., Ottawa, Ontario K1H 1C4, and Department of Medical Physics, Ottawa Hospital Regional Cancer Centre, 503 Smyth Rd. Ottawa, Ontario K1H 1C4. Radiotherapy dosimetry using a commercial OSL system. United States: N. p., 2008. Web. doi:10.1118/1.2841940.
Viamonte, A., Rosa, L. A. R. da, Buckley, L. A., Cherpak, A., Cygler, J. E., Instituto de Radioprotecao e Dosimetria, Department of Medical Physics, Ottawa Hospital Regional Cancer Centre, 503 Smyth Rd., Ottawa, Ontario K1H 1C4, & Department of Medical Physics, Ottawa Hospital Regional Cancer Centre, 503 Smyth Rd. Ottawa, Ontario K1H 1C4. Radiotherapy dosimetry using a commercial OSL system. United States. doi:10.1118/1.2841940.
Viamonte, A., Rosa, L. A. R. da, Buckley, L. A., Cherpak, A., Cygler, J. E., Instituto de Radioprotecao e Dosimetria, Department of Medical Physics, Ottawa Hospital Regional Cancer Centre, 503 Smyth Rd., Ottawa, Ontario K1H 1C4, and Department of Medical Physics, Ottawa Hospital Regional Cancer Centre, 503 Smyth Rd. Ottawa, Ontario K1H 1C4. 2008. "Radiotherapy dosimetry using a commercial OSL system". United States. doi:10.1118/1.2841940.
@article{osti_21120634,
title = {Radiotherapy dosimetry using a commercial OSL system},
author = {Viamonte, A. and Rosa, L. A. R. da and Buckley, L. A. and Cherpak, A. and Cygler, J. E. and Instituto de Radioprotecao e Dosimetria and Department of Medical Physics, Ottawa Hospital Regional Cancer Centre, 503 Smyth Rd., Ottawa, Ontario K1H 1C4 and Department of Medical Physics, Ottawa Hospital Regional Cancer Centre, 503 Smyth Rd. Ottawa, Ontario K1H 1C4},
abstractNote = {A commercial optically stimulated luminescence (OSL) system developed for radiation protection dosimetry by Landauer, Inc., the InLight microStar reader, was tested for dosimetry procedures in radiotherapy. The system uses carbon-doped aluminum oxide, Al{sub 2}O{sub 3}:C, as a radiation detector material. Using this OSL system, a percent depth dose curve for {sup 60}Co gamma radiation was measured in solid water. Field size and SSD dependences of the detector response were also evaluated. The dose response relationship was investigated between 25 and 400 cGy. The decay of the response with time following irradiation and the energy dependence of the Al{sub 2}O{sub 3}:C OSL detectors were also measured. The results obtained using OSL dosimeters show good agreement with ionization chamber and diode measurements carried out under the same conditions. Reproducibility studies show that the response of the OSL system to repeated exposures is 2.5% (1sd), indicating a real possibility of applying the Landauer OSL commercial system for radiotherapy dosimetric procedures.},
doi = {10.1118/1.2841940},
journal = {Medical Physics},
number = 4,
volume = 35,
place = {United States},
year = 2008,
month = 4
}
  • Purpose: In highly-conformal radiotherapy, due to the complexity of both beam configurations and dose distributions, traditional in vivo dosimetry is unpractical or even impossible. The ideal dosimeter would be implanted inside the planning treatment volume so that it can directly measure the total delivered dose during each fraction with no additional uncertainty due to calculation models. The aim of this work is to verify if implantable metal oxide semiconductors field effect transistors (MOSFETs) can achieve a sufficient degree of dosimetric accuracy when used inside extracranial targets undergoing radiotherapy treatments using the Cyberknife system. Methods: Based on the preliminary findings ofmore » this study, new prototypes for high dose fractionations were developed to reduce the time dependence for long treatment delivery times. These dosimeters were recently cleared and are marketed as DVS-HFT. Multiple measurements were performed using both Virtual Water and water phantoms to characterize implantable MOSFETs under the Cyberknife beams, and included the reference-dosimetry consistency, the dependence of the response on the collimator size, on the daily delivered dose, and the time irradiation modality. Finally a Cyberknife prostate treatment simulation using a body phantom was conducted, and both MOSFET and ionization readings were compared to Monte Carlo calculations. The feasibility analysis was conducted based on the ratios of the absorbed dose divided by the dose reading, named as ''further calibration factor'' (FCF). Results: The average FCFs resulted to be 0.98 for the collimator dependence test, and about 1.00 for the reference-dosimetry test, the dose-dependence test, and the time-dependence test. The average FCF of the prostate treatment simulation test was 0.99. Conclusions: The obtained results are well within DVS specifications, that is, the factory calibration is still valid for such kind of treatments using the Cyberknife system, with no need of further calibration factors to be applied. The final accuracy of implantable MOSFETs when used for such kind of treatments was estimated to be within {+-}4%. Additional investigations using dose/fraction higher than 12 Gy, different beam configurations, and tracking systems could extend the present findings to other kind of treatments. MOSFET technology was proven to have high versatility in fast adaptation of existing detectors to new applications. It is plausible to expect a general feasibility of implantable MOSFET technology for in vivo dosimetry of the extracranial-targets treatments using the Cyberknife, provided each particular application will be validated by suitable both physical and clinical studies.« less
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