Temperature dependence of polymer-gel dosimeter nuclear magnetic resonanceresponse

The purpose of this study was to find a physical-mathematical description c apable to correct a polymer-get dosimeter relaxation rate R-2-dose response for different temperatures. Four different modifications of polymer-gel do simeters were used in this study. Samples with polymer-gel dosimeter in gla ss test vessels were homogeneously irradiated by Co-60 gamma photons. A mul ti-echo sequence with 16 equidistant echoes was used for evaluation of irra diated polymer-gel dosimeters. The sequence parameters were as follows: TR 2000 ms, TE 22.5-360.0 ms, slice thickness 5 mm, FOV 255 mm, one acquisitio n. The proposed description recommends to subtract R-2 response of the noni rradiated dosimeter from the total R-2-dose response. The relaxation rate f or the irradiated dosimeter can be expressed as a function of temperature a nd dose. The temperature dependence has an exponential behavior in the meas ured range. The proposed description allows to correct the measured NMR R-2 -dose responses for different temperatures. (C) 2001 American Association o f Physicists in Medicine.