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SU‐FF‐T‐208: Evaluation of a New Radiochromic Film/Flatbed Scanner System for Planar Clinical Dosimetry
Author(s) -
Goss M,
Oldham M
Publication year - 2007
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 - 10.1118/1.2760869
Subject(s) - scanner , dosimetry , reproducibility , materials science , irradiation , optics , linear particle accelerator , nuclear medicine , planar , ionization chamber , dose profile , physics , computer science , mathematics , ion , medicine , nuclear physics , computer graphics (images) , beam (structure) , statistics , quantum mechanics , ionization
Purpose: To assess the accuracy and practicality of using GAFCHROMIC® EBT Film in combination with an Epson flat‐bed scanner for the verification of advanced treatment techniques in radiation therapy. The combination of EBT with flat‐bed scanner may represent a low cost and convenient alternative to currently used dosimetry systems. Methods and Materials: First the scanner temporal stability and variability of light source over the scanning area was investigated. Next the dependence on color bit‐depth was investigated by conducting scans of the same film using different bit‐depth parameters. The dose response and stability of EBT film was investigated in the range 0 to 8Gy with 6MV photon beams, and a depth‐dose comparison was made using 16× electrons to known ion chamber measurements. Intra and inter‐batch film reproducibility was investigated as well as dependence of OD on temperature at irradiation over a range of 10°C. Results: The reproducibility of the Epson scanner was found to be highly stable, to within 1.01%, over all ranges of OD studied. A slight non‐uniformity in background was observed, but this background was consistent enabling efficient correction. 48‐bit color depth was adopted for all experiments. The dose response curve of EBT film was found to be non‐linear but stable (within 1.06%) from immediately after irradiation to within one week after irradiation. The electron PDD curve showed excellent agreement with clinical PDD tables at all depths with the linac data. A maximum intra‐batch OD difference of 1.88% was observed, while a maximum OD difference of 5.76% was observed for samples from the same batch. The temperature sensitivity was found to be small, with maximum difference of 1.03% in optical density over the range of 10°C. Conclusions: The Epson® 4990 Scanner/ GAFCHROMIC® EBT Film dosimetry combination appears an accurate and convenient dosimetry system for radiation therapy.