Novel liquid dosimeters for low-energy electron beam irradiation in low and medium dose ranges

Low-energy electron beam irradiation, which refers to the treatment of matter with accelerated electrons at energies below 300 keV, is gaining attention for many applications in life sciences. In the scope of vaccine production, low-energy electron irradiation is an efficient and chemical free technology to inactivate viruses. Low-energy electron beam irradiation has also been proposed to be a powerful technique for its use in biotechnological processes. As biotechnological applications operate in an aqueous environment, there is an urgent need for accurate dose quantification in liquids, especially for low (<500 Gy) and medium doses (500-5000 Gy). This study investigated dye solutions of xylenol orange tetrasodium, 1,9-dimethylmethylene blue, resazurin sodium, and tartrazine for their suitability as radiochromic liquid dosimeters. The solutions were evaluated regarding their dose-response characteristics and storage stability prior to irradiation over a range of pH values and concentrations. The radiochromic dosimeters were irradiated with electrons with maximal energies of 200 keV and dose rates of 6.5 Gy/s to 45 Gy/s. Then, the absorbance was measured and response curves were plotted. The dye solutions of 1,9-dimethylmethylene blue and resazurin sodium covered a low to medium dose range from 100-1500 Gy and 100-1000 Gy, respectively. Tartrazine at pH 4 was suitable for quantification of doses from 100 Gy to 3500 Gy, which covers a wide dose range of biotechnological applications.