A new polymer gel for magnetic resonance imaging (MRI) radiation dosimetry

New composition polymer gels, the N-vinylpyrrolidone argon (VIPAR) gels, we re developed and investigated as MRI dosimeters. VIPAR gels were irradiated in the dose range of 0-12 Gy by a 6 MV x-ray linear accelerator and MR-sca nned in a 1.5 T magnetic resonance imager. A linear relationship was found between absorbed dose and spin-spin relaxation rate R-2. The dose sensitivi ty was found to be similar to 0.1 s(-1) Gy(-1) for a gel composition of 4% w/w in N-vinylpyrrolidone, 4%, w/w in N, N'-methylene-bisacrylamide, 5% w/w in gelatine type A and 87% w/w in water. This dose sensitivity was stable with time and did not deteriorate even when a boost radiation dose of 2.5 G y was applied 15 days after the first irradiation. Good reproducibility of these results was observed when a new batch of gels was produced and used f or corresponding measurements and analysis.