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Determination of the 4 mm Gamma Knife helmet relative output factor using a variety of detectors
Author(s) -
Tsai JenSan,
Rivard Mark J.,
Engler Mark J.,
Mignano John E.,
Wazer David E.,
Shucart William A.
Publication year - 2003
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 - 10.1118/1.1567736
Subject(s) - detector , physics , variety (cybernetics) , optics , dosimetry , gamma ray , nuclear medicine , medical physics , nuclear physics , mathematics , medicine , statistics
Though the 4 mm Gamma Knife helmet is used routinely, there is disagreement in the Gamma Knife users community on the value of the 4 mm helmet relative output factor. A range of relative output factors is used, and this variation may impair observations of dose response and optimization of prescribed dose. To study this variation, measurements were performed using the following radiation detectors: silicon diode, diamond detector, radiographic film, radiochromic film, and TLD cubes. To facilitate positioning of the silicon diode and diamond detector, a three‐dimensional translation micrometer was used to iteratively determine the position of maximum detector response. Positioning of the films and TLDs was accomplished by manufacturing custom holders for each technique. Results from all five measurement techniques indicate that the 4 mm helmet relative output factor is 0.868 ± 0.014 . Within the experimental uncertainties, this value is in good agreement with results obtained by other investigators using diverse techniques.