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Title: Quality assurance and independent dosimetry for an intraoperative x-ray device

Abstract

Purpose: Quality assurance is an essential component of accurate and safe radiotherapy delivery, and should include measurements which are independent of manufacturer-provided calibration. However, the physical and dosimetric properties of the INTRABEAM compact mobile 50 kV x-ray source are different from conventional kilovoltage therapy units and few reports describe methods for independent checks, frequencies, or tolerances for quality assurance tests. Methods: Based on the available evidence and local experience, methods are described for determination of the key dosimetric parameters: beam quality, output, isotropy, and depth doses. Internal system checks are also described, along with measurements of long-term stability. Results: A small volume parallel plate ionization chamber in a liquid water tank is the gold standard for measurements with this unit, but solid water-equivalent materials, thermoluminescent dosimeters and radiochromic film can all be used as practical alternatives with an accuracy of 5%-10%. The main cause of measurement uncertainty is positioning of the detector in the steep dose gradient, but energy dependence should also be considered. Conclusions: A quality assurance schedule with suggested tolerances is proposed, which includes both internal tests, before each treatment and on a monthly basis, and independent tests every year or after servicing or recalibration.

Authors:
 [1]
  1. Radiotherapy Physics, Royal Free Hospital, London NW3 2QG (United Kingdom)
Publication Date:
OSTI Identifier:
22099085
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 39; Journal Issue: 11; Other Information: (c) 2012 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; 62 RADIOLOGY AND NUCLEAR MEDICINE; 60 APPLIED LIFE SCIENCES; ACCURACY; BRACHYTHERAPY; CALIBRATION; DEPTH DOSE DISTRIBUTIONS; DOSIMETRY; ENERGY DEPENDENCE; FILMS; IONIZATION CHAMBERS; QUALITY ASSURANCE; RADIATION DOSES; THERMOLUMINESCENT DOSEMETERS; WATER; X RADIATION; X-RAY SOURCES

Citation Formats

Eaton, D. J. Quality assurance and independent dosimetry for an intraoperative x-ray device. United States: N. p., 2012. Web. doi:10.1118/1.4761865.
Eaton, D. J. Quality assurance and independent dosimetry for an intraoperative x-ray device. United States. doi:10.1118/1.4761865.
Eaton, D. J. Thu . "Quality assurance and independent dosimetry for an intraoperative x-ray device". United States. doi:10.1118/1.4761865.
@article{osti_22099085,
title = {Quality assurance and independent dosimetry for an intraoperative x-ray device},
author = {Eaton, D. J.},
abstractNote = {Purpose: Quality assurance is an essential component of accurate and safe radiotherapy delivery, and should include measurements which are independent of manufacturer-provided calibration. However, the physical and dosimetric properties of the INTRABEAM compact mobile 50 kV x-ray source are different from conventional kilovoltage therapy units and few reports describe methods for independent checks, frequencies, or tolerances for quality assurance tests. Methods: Based on the available evidence and local experience, methods are described for determination of the key dosimetric parameters: beam quality, output, isotropy, and depth doses. Internal system checks are also described, along with measurements of long-term stability. Results: A small volume parallel plate ionization chamber in a liquid water tank is the gold standard for measurements with this unit, but solid water-equivalent materials, thermoluminescent dosimeters and radiochromic film can all be used as practical alternatives with an accuracy of 5%-10%. The main cause of measurement uncertainty is positioning of the detector in the steep dose gradient, but energy dependence should also be considered. Conclusions: A quality assurance schedule with suggested tolerances is proposed, which includes both internal tests, before each treatment and on a monthly basis, and independent tests every year or after servicing or recalibration.},
doi = {10.1118/1.4761865},
journal = {Medical Physics},
issn = {0094-2405},
number = 11,
volume = 39,
place = {United States},
year = {2012},
month = {11}
}