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Evaluation of a computed radiography system for megavoltage photon beam dosimetry
Author(s) -
Olch Arthur J.
Publication year - 2005
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2012787
Subject(s) - dosimetry , quality assurance , calibration , materials science , dose profile , reproducibility , computed radiography , optics , medical imaging , digital radiography , linear particle accelerator , photon , beam (structure) , nuclear medicine , medical physics , radiography , image quality , computer science , physics , medicine , chemistry , nuclear physics , external quality assessment , pathology , quantum mechanics , chromatography , artificial intelligence , image (mathematics)
Computed radiography (CR) systems have been gaining adoption as digital replacements for film for diagnostic and therapy imaging. As a result, film processors are being removed from service, leaving a void for the medical physicists who use film and processors for two‐dimensional megavoltage beam dosimetry. This is the first report to evaluate the ability of a commercial CR reader and storage phosphor plate system to accurately quantitate absolute dose and dose distributions from a 6 MV photon beam. There are potential advantages and disadvantages of current CR systems compared to film systems. CR systems inherently produce a linear dose‐response over several logs of dose. However, the barium in the storage phosphor has a higher atomic number than the silver in film, resulting in significant energy sensitivity. The purpose of this work is to fully characterize the impact of these and other features of this CR system relevant to dosimetry. The tests performed and reported on in this study include uniformity of readout across a uniform field, geometrical accuracy, intra‐ and interday reproducibility, signal decay with time and with light exposure, dose‐to‐signal calibration, high dose effects, obliquity effects, perpendicular and parallel calibration results, field size and depth of measurement effects and the use of lead filters to minimize them, and intensity modulated radiation therapy quality assurance test results compared to that for film. Practical techniques are provided to optimize the accuracy of the system as a dosimetric replacement for film.