Improving dose sensitivity of N-vinyl caprolactam polymer gel dosimeters with sodium chloride additive

In this work, the first evaluation of inorganic salt sodium chloride (NaCl) sensitizer material on N-vinyl caprolactam (NVCL) polymer gel dosimeter was presented and evaluated with different concentrations of NVCL monomer and different types of gelatins. The improved NVCL-NaCl dosimeters were exposed to radiation from a medical linear accelerator across various doses up to 20 Gy. By utilizing NMR spectroscopy, the relaxation rate (R₂) of the polymers was measured before and after irradiation. The dose response of the improved gel at different concentrations of NaCl, monomers NVCL, and at different types of gelatins were investigated. At a concentration of 6 wt% NaCl, the sensitivity of NVCL-NaCl was approximately 1.4 times higher than that of the same gel without NaCl, specifically within the linear dose response range of 0 to 10 Gy, which is significant result. Gelatin type A response is slightly higher than type B response by 3%, with increased sensitivity from 0.25 to 0.28 Gy⁻¹ s⁻¹. Additionally, the changes in the energy of the photons, the dose rate, and the temperature during irradiation did not notably affect the formulation of the NaCl-infused gel. the correlation between the absorbed dose and the resulting response remained consistent over a span of five days after the irradiation took place. NaCl acts as a good sensitizer and contributes significantly to the polymerization of the NVCL polymer samples after irradiation.