Effect of the glucono-δ-lactone concentration on the sensitivity and stability of PVA-GTA-I radiochromic gel dosimeter

The present study explored the influence of the varying concentrations of a proton generator, glucono-δ-lactone (GDL), promoting a cross-linking of the matrix to the dose-response of a PVA-GTA-I radiochromic gel dosimeter. This gel dosimeter was composed of iodide and polyvinyl alcohol crosslinked with glutaraldehyde (GTA) and combined with additives of GDL and fructose. Six sets of gel samples with GDL concentrations ranging from 50 to 300 mM was irradiated with 1–10 Gy doses using 137Cs gamma-rays. Dose response and temporal stability of the absorbance in the gel dosimeter as a function of the GDL concentration were investigated. The dose-response data showed good linearities in the dose range of 0–10 Gy from all GDL concentrations measured 48 h post-irradiation. The sensitivity became higher with increasing GDL concentration, but smaller increments were observed at higher GDL concentrations and then completely saturated around 250 mM. The recorded sensitivities from the PVA-GTA-I gel dosimeters were 3–4 times higher than PVA-I and LCV micelle gel dosimeters. Temporal stability data showed a similar trend in GDL concentrations of 100–300 mM, where a sharp increase of absorbance was seen in the first 24 h and then small fluctuations were observed up to 168 h post-irradiation. Meanwhile, the samples with 50 mM of GDL showed a gradual increase in absorbance after 48 h post-irradiation. Higher GDL concentrations tended to increase the rate of auto-oxidation.