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The determination of dose characteristics of ruthenium ophthalmic applicators using radiochromic film
Author(s) -
Taccini G.,
Cavagnetto F.,
Coscia G.,
Garelli S.,
Pilot A.
Publication year - 1997
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 - 10.1118/1.598117
Subject(s) - dosimetry , materials science , monte carlo method , standard deviation , dose profile , homogeneity (statistics) , nuclear medicine , optics , radiation , biomedical engineering , physics , mathematics , medicine , statistics
Ruthenium ophthalmic applicators are energetic beta ray sources, supplied in several shapes and dimensions, and used in intraocular tumor therapy. Because of their small dimensions, the determination of dosimetric characteristics represents a technical challenge. We developed a semi‐automatic method to define surface dose, dose distribution, and percentage depth dose of such applicators using radiochromic dosimetric media. These detectors consist of a thin (7 μm) radiation sensitive layer on polyester base (100 μm total thickness) changing color as a function of radiation exposure. Transmission images of exposed films were then grabbed with a TV‐digitizer system to obtain a gray‐level image from which dosimetric characteristics such as isodose distribution, dose values, and homogeneity of nuclide distribution were derived. Good agreement between experimental results and Monte Carlo simulation performed using the GEANT 3 code, appear to be a confirmation of the validity of the method. Moreover while manufacturer specifications of absolute and relative dose rates present a standard deviation error of ± 30 % on dose rate and ± 6 % on accuracy of relative dose values, the proposed method reduces the errors to ± 10 % and ± 4 % , respectively.