[Comparison evaluation of polymer gel with a water phantom.]

We have investigated the properties of three polymergels: G gel, A gel, and C gel. These polymer gels changed only the chemical reagent for the gel. The water equivalence was determined by comparing the polymer gels macroscopic photon and electron interaction cross sections over the energy range from 10 KeV to 50 MeV and by Monte Carlo modeling of percentage depth doses. Polymer gels have a chemical reagent for the gel and monomer concentration and therefore their mass density is up to 1.70-2.91 % higher than water. This results in differences between the cross section ratios of the polymer gels and water of up to 0.01-3.00 % for the attenuation coefficients ratio and relative stopping power throughout the energy range. Monte Carlo modeling was done for the polymer gels to model the electron and photon transport resulting from a 6 MV photon beam. The absolute percentage differences between each gel and water were within 1 % of the relative percentage differences. The results showed that the A gel formulation had the most suitable water equivalence of the polymer gels investigated due to its lower mass density measurement compared with G gel and C gel.