Radiotherapy widely uses the polymer gel dosimeter. The advantage of polymer gel dosimetry is the mapped 3D absorbed dose
distribution that other dosimeters cannot achieve. The Acrylamide (AAm) is a frequently used monomer; however, the extreme
toxicity of Acrylamide (ORL-RAT LD50: 124 mg/kg) raises a concern. Therefore, this study developed a new type of Propylene
acid based gel dosimeter, named DEMBIG gel. The following outlines the aim of this study: (1) using two-point formulation
to find the optimal scan parameter of MRI according to the best sensitivity and linearity (correlation coefficient) of DEMBIG
gel, (2) using the optimal scan parameter of MRI to observe the properties of DEMBIG gel, and (3) verifying the three-dimensional
(3D) dose distributions of radiotherapy. This study obtained three major results: 1. The scan protocol of MRI was established.
2. The preliminary results of DEMBIG gel were: (1) The range of absorbed dose of DEMBIG gel: 0–20 Gy. (2) The sensitivity
and correlation coefficient of DEMBIG gel at verification as slope: 0.181 sGy−1, R2:0.997. (3) There is no energy dependency of the DEMBIG gel. 3. The dose difference was 3% in the three-dimensional (3D) isocenter
dose in clinical radiotherapy. These data show that DEMBIG gel is a potential candidate for the 3D dosimeter.