Yeast-Based Impedance Biodosimetry for Retrospective Assessment of Radiation Exposures

Saccharomyces cerevisiae yeast cells were investigated as fortuitous dosimeters for retrospective assessments of exposures following large-scale radiological or nuclear accidents. The radiation response of yeast cells was examined by using cellular metabolic activity and electrical impedance of the solution to evaluate dose. Active laboratory-grade dry yeast cells were used as the biological material as these samples are simple to handle and have a long shelf-life. A novel dosimeter design was developed with precise fabrication and measurement procedures to ensure reproducibility of samples was achievable. To assess the feasibility of impedance biodosimetry, a dose-response curve was developed by irradiating S. cerevisiae cells from 0.5 Gy to 8 Gy using a ¹³⁷Cs gamma source. The dose-response curve showed a linear relationship of dose with changes in the impedance response. Additionally, in a separate experiment, the detection limit of this technique was determined to be 300 mGy. Fading of the impedance signal was also investigated, where no noticeable decrease in the response over a 7-month period was observed. Finally, the impedance and radiation response of Fleischmann's® yeast was examined, and it was found that commercially available yeast exhibit a similar response to laboratory-grade yeast. S. cerevisiae cells were determined to be suitable and convenient samples to use for retrospective dosimetry applications since they are widely available and require no additional processing. In the event of a radiological accident, yeast-based impedance biodosimetry could be used as an alternative technique to evaluate initial dose estimates to exposed areas.