ABSORBED DOSE MEASURMENTS USING POLYMER/GEL CHAMBERS

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DESCRIPTION: The investigators propose to test the feasibility of developing a gel-based dosimeter with tissue mimicking properties that would be read by change in NMR or optical signal due to an X-ray dose- related polymerization, as further described by their abstract: "This proposal aims to develop tissue-equivalent polymer-gel chambers as substitutes for conventional ionization chambers, and to establish the feasibility of designing simple photometers or bench-top NMR relaxometers to measure radiation doses accurately. X-ray, electron and heavy-charged-particle beams are routinely calibrated with ionization chambers, which present a complex theoretical problem: how to convert the electrical charge from air ionization to the energy absorbed per mass of tissue. The calibration of radiations above 1 MeV requires that the ionization chamber first be calibrated for 60Co gamma rays at a national or regional laboratory. Subsequently, this calibration factor and as many as a dozen other chamber-and radiation-dependent parameters are applied to obtain the tissue dose. The uncertainty in the tissue- dose determination is + 3%. The polymer-gel dosimeter is tissue (muscle) equivalent so that, after calibration at one energy, the dose-to-muscle at another energy is obtained without complex corrections. The overall goal of the proposed research is to demonstrate that small polymer-gel chambers can be reliably constructed and used to calibrate radiation bemas, and to design the instrumentation (optical or NMR relaxation measuring devices) needed to provide a novel, clinical dosimetry system." PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE