Optical properties of polymerization N-(3-methoxypropyl) acrylamide polymer gel dosimeters for radiotherapy

The purpose of this paper is to evaluate the dosimetric properties of N-(3-methoxypropyl) acrylamide (NMPA) polymer gel dosimeter using UV-vis spectrophotometry as a simple and low-cost method.

The gel samples have been irradiated to various doses using a medical linear accelerator with 6 MV beam energy. The optical density of un-irradiated and irradiated NMPA polymer gel dosimeters in terms of absorbance at 500 nm was investigated by UV-vis spectrophotometry.

The absorbance values of the gel samples were increased linearly with increasing dose in the dose range between 2 and 20 Gy. A remarkable improvement in the dose response was noticed after the addition of various concentrations of glycerol. The impact of dose rate, beam energy and the post-stability of the exposed gels was studied and found consistent with the previous study using nuclear magnetic resonance results (energy independent and dose rate independent, stable up to one week).

The results of the independent experimental spectrophotometry and nuclear magnetic resonance analyses indicate that the NMPA polymer gel dosimeter has good and consistent dosimetric features for radiotherapy dosimetry.

The ionizing radiation-induced polymerization of gel samples leads to a change in the absorbance of the irradiated gel samples. This study introduces the first characterization of NMPA gel dosimeter by means of UV-vis spectrophotometer.