Development of fluorescein-based dosimeter for radiation processing applications

Dosimetry forms an inseparable part of radiation processing. Many dosimeters are available to cover wide range of doses used in radiation processing. These include the Fricke, ceric-cerous, alanine ESR Alanine (Electron Spin Resonance Technique), dichromate, and radiochromic films. Low-dose radiation processing applications (<2 kGy) such as insect disinfestation, shelf-life extension, and sprout inhibition use imported dosimeters. At present, radiochromic films/waveguides are used for low-dose applications; however, the dosimeters are costly and subject to sanctions and supply restrictions from country of origin. The present work discusses the development of system that can be used as a routine dosimeter for radiation processing facilities in the dose range of 200–2500 Gy. Iodine is generated by the action of radiolysis products of water on iodide and iodate present. Generated iodine halogenates fluorescein to erythrosine with the help of bicarbonate. Increase in absorbance due to the formation of erythrosine can be related to the absorbed dose and used in routine dosimetric applications. As the change is radiochromic, it advantageously provides a visual indication of dose received.