Enhancing Fricke Xylenol Gel Dosimeter’s Response to Radiation with Optimized Preparation Methods

Abstract

Introduction: The fundamental principle of the Fricke gel dosimeter involves the oxidation of ferric ions upon exposure to radiation. However, a significant limitation of this dosimeter is the post-irradiation diffusion of ferric ions, which can result in the degradation of spatial dose information. Material and Methods: Gels were prepared using 300 bloom gelatin, deionized water, sulfuric acid, ferrous ammonium sulfate, and xylenol orange dye (Sigma-Aldrich). The solution was then poured into 10 ml plastic cuvettes. The gel samples were refrigerated at various temperatures for 1 to 10 days and irradiated within a water bath environment utilizing a telecobalt unit (Phoenix, Theratronics) employing parallel opposed beams. Spectrophotometric analysis at a wavelength of 585 nm was used to measured optical density changes with dose. This procedure was repeated across gel formulations prepared under differing pH conditions. Results: The gel’s optimum pH value, which was stored for 10 days at 5° C, showed a linear response up to 10 Gy, although the storage time was longer than that of the gels with low (0.3) and high pH (1.3). The auto oxidation rate was determined and found to be less for non-irradiated gel batches stored at 5° C in relation to the gel samples at room temperature and freezing temperature. Conclusion: The dose response of the dosimeter is highly dependent on its pH, composition, alkaline residuals, and pre-irradiation storing conditions. We observed the optimum pH is 1, at which the dosimeter shows a maximum response. Storing gel samples at 5°C notably reduces the Fe2+ to Fe3+ auto-oxidation rate. © (2025), (Mashhad University of Medical Sciences). All rights reserved.