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SU‐GG‐T‐308: Polymer Cross‐Linking and Sensitivity Enhancement in Normoxic Polymer Gels Used for Three‐Dimensional Dosimetry
Author(s) -
Martin R,
BenComo J,
Heard M,
Martin M,
Kaluarachchi K,
Wells N,
Sadagopan R
Publication year - 2008
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 - 10.1118/1.2962060
Subject(s) - polymer , dosimetry , materials science , irradiation , methacrylic acid , sensitivity (control systems) , analytical chemistry (journal) , monomer , chemistry , nuclear medicine , chromatography , composite material , nuclear physics , physics , medicine , electronic engineering , engineering
Purpose: To discuss the relation between cross‐linking and sensitivity enhancement in normoxic polymer gels in a dose range suitable for intensity modulated radiotherapy, based on considerations related to actual sensor preparation methods and a theoretical description of the optical behavior of irradiated polymer gel when dose maps are obtained through optical CT. Method and Materials: Two set of samples of MAGIC gel (9% in weight of methacrylic acid) were prepared at 37°C and 45°C and irradiated with a60 Co and 6 MV photon beams to doses in the range from 0.1 to 5 Gy. The samples were scanned in an optical CT. Non‐irradiated samples were also scan. A theory based on the number of sites for water solvation, which takes into account polymer cross‐linking, is introduced in order to explain the observed changes in the optical density. The slope of the polymer gel response to dose is a measurement of sensitivity and it is analyzed for the actual experimental conditions as well as those for the optimum in connection to cross‐linking phenomena. Conclusion: The analysis showed a proper monotonic behavior for the polymer gel response and maximum sensitivity when cross‐linking occurs in an important fraction in the preparation process.