Novel Fricke gel dosimeter based on polyethylene oxide and sodium thiocyanate

The Fricke solution, consisting of ferrous ammonium sulfate in aqueous sulfuric acid , serves as a widely used chemical dosimeter for gamma rays , X-rays, and high-energy electrons. It is recognized as a reference standard dosimeter in radiation chemistry and can measure absorbed doses without calibration, provided metrological traceability is not required. Modifying the conventional Fricke dosimeter involved incorporating a gelling agent , enabling the measurement of the volumetric distribution of the absorbed dose. Additionally, ion indicators such as xylenol orange were included to improve gel stability and facilitate optical analyses for dosimetric calculations. This study proposes a new Fricke gel formulation using polyethylene oxide (PEO) as the gelling agent and sodium thiocyanate as the ion indicator. After exposure to a cobalt-60 source at the Gamma Irradiation Laboratory of the Nuclear Technology Development Center in Belo Horizonte, Brazil, dose-response evaluation via spectrophotometry showed that the PEO-based Fricke gel with sodium thiocyanate exhibited a linear dose-response under gamma radiation. The PEO-based dosimeter demonstrated a higher sensitivity compared to Fricke gel formulated with agarose as the gelling agent. • A new PEO-based Fricke dosimeter formulation with sodium thiocyanate has been development. • Sodium thiocyanate was used as an ion indicator in this formulation. • The dose profile was obtained from spectrophotometry.