The primary goal of radiation therapy is to deliver a sufficient radiation dose to a target volume while minimizing the dose to surrounding healthy tissue. In this study the dose response of methacrylic acid-gelatin (MAG) polymer gel dosimeter using different type of anti-oxidants; ascorbic acid (AscA) and tetrakis-hydroxy-methyl-phosphonium chloride (THPC) is determined by using single spin echo sequence magnetic resonance imaging (MRI). The concentrations of methacrylic acid (MAA) were varied and using MRI, the optimal formulation that gives the maximum R2-dose response of the polymer gel upon irradiation was determined. The polymer gel was irradiated using a 6 MV photon from a linear accelerator (LINAC) for a dose range varying from 0 to 20 Gy. The transverse relaxation rates (R2) of the irradiated gels from MRI were read. A linear relationship between dose and R2 was obtained for a dose range of 0 to 20 Gy for MAG gel composed of ascorbic acid (MAGAS) and linear response from 0 to 10 Gy for MAG gel composed of THPC (MAGAT). The sensitivity of MAGAS showed lower sensitivity compared to MAGAT. The optimum concentrations for the MAGAS and MAGAT polymer gel were 6% MAA and 5% gelatin as it gave the highest sensitivity of 0.0989 s-1Gy-1 and 1.1180 s-1Gy-1 respectively. The results are compared to Multiple Spin Echo Sequence MRI.