Evaluation of the dynamic mechanical behavior of polymer gel dosimeter

In this preliminary work, we present Magnetic Resonance Elastography (MRE) as a tool to study the mechanical properties of ‘MAGIC’ polymer-gel dosimeter. For this purpose, a set of gels were submitted to radiation doses from 10 to 30 Gy, and their responses to shear wave excitation were studied. We investigated the dynamic mechanical response (shear modulus) of the gel to driver frequency range of 100 to 250 Hz. The shear waves speeds in the gel were registered and converted to elastograms to show the radiation-induced changes in the elasticity distribution. To compare the elastograms behavior, parametric images of Nuclear Magnetic Resonance (NRM) spin-spin relaxation rate (R2=1/T2) were acquired and then converted to dose distribution maps. For the lowest and highest absorbed dose, a 2D correlation coefficient between these two imaging techniques ranged from 0.990 to 0.993, respectively. As expected, all gel dosimeters showed a monotonical increasing in its shear modulus as the values of absorbed dose and driver frequency increased. The results of this study showed that MRE elastograms have potential to visualize and quantify dose distribution in polymer gel dosimeters.