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SU‐FF‐T‐356: Preliminary Investigations of a Leucomalachite Green Hydrogel for Three‐Dimensional Radiation Dosimetry
Author(s) -
Jordan K,
Avvakumov N,
Battista J
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 - 10.1118/1.2761020
Subject(s) - dosimeter , xylenol orange , materials science , dosimetry , cuvette , gelatin , irradiation , self healing hydrogels , attenuation , radiochemistry , analytical chemistry (journal) , optics , nuclear chemistry , chromatography , chemistry , nuclear medicine , medicine , biochemistry , physics , nuclear physics , polymer chemistry
Purpose: To develop a radiochromic hydrogel dosimeter based on the conversion reaction of leuco‐triphenyl‐methane dye to coloured dye. Method and Materials: A systematic examination of surfactants revealed that Triton X‐100 provided adequate solubility to keep leucomalachite green dissolved in 4% gelatin hydrogels. The gel dose response was increased by lowering the pH and by adding trichloroacetic acid. A cylindrical one litre volume sample was irradiated with a 12 MeV electron beam (Varian Clinac 2100C) to a dose of 30 Gy and scanned with a commercial optical cone beam CT scanner (Vista™, Modus Medical Devices Inc.). Results: The most radiation sensitive gel formulation contained: 4% gelatin, 6 mM Triton X‐100, 15mM trichloroacetic acid and 0.1 mM leucomalachite green. A dose response of 0.005 cm −1 Gy −1 was determined from irradiation of gel‐filled 1 cm pathlength polymethymethacrylate cuvettes and measurement of the optical attenuation improved at a wavelength equal to 633 nm. Comparison of the central axis gel attenuation coefficients normalized at depth of maximum dose (d max ) with TG21‐corrected ion chamber data, demonstrated agreement in the buildup region up to d max . However, the gel over‐responded at greater depths. Conclusion: Leuco dyes can be dissolved to provide transparent, colourless hydrogels by employing surfactants such as Triton X‐100. The current gel formulation has a dose response approximately 20 times lower than the ferrous xylenol orange system. It is suggested that photochemistry arising from the UV light generated by the Triton X‐100 scintillation fluorescence and the Cerenkov process are possible causes of a radiochromic artifact measured with electron beams. Conflict of Interest: Two of the authors (KJ, JB) have a licensing agreement with Modus Medical Devices Inc. concerning the commercialization of Vista™.