Characterization of the chemical stability of irradiated N-isopropylacrylamide gel dosimeter

An investigation of the normoxic NIPAM gel dosimeter has been undertaken. The NIPAM gel dosimeter used in the current study was mainly composed of gelatin, NIPAM, N,N'-methylenebisacrylamide (BIS), and distilled water. This study aims to measure the change in the chemical structure of the NIPAM gel dosimeter after irradiation via the C-13-NMR, H-1-NMR, and Fourier transform Raman (FT-Raman) spectra. The C-13-NMR experimental results show that the C = C bonds of NIPAM and BIS are at 126.74 and 131.62 ppm, respectively. The intensity of the C-C bond of the NIPAM gel dosimeter increases with the absorbed dose, and the dose-intensity curve of the C-C bond is determined by y = 0.0506 + 79.9(1-e(0.16x)) (R-2=0.9997). H-1-NMR and FT-Raman can also effectively determine the positions of the C = C bonds of NIPAM and BIS, and the intensity decreases as the absorbed radiation dose increases. Hence, C-13-NMR, H-1-NMR, and FT-Raman spectrometers can effectively detect the changes in the chemical structure of the polymer gel dosimeter after irradiation and successfully determine the D-50 dosage in the NIPAM gel dosimeter. Crown Copyright (c) 2013 Published by Elsevier Ltd. All rights reserved.