The Use of Electron Spin Resonance Techniques to Determine Gamma Ray Exposure of Alpha-Keratin in Human Hair

This study explored the use of electron spin resonance (ESR) techniques to measure gamma ray exposure in human hair, specifically $\alpha$-keratin. Hair samples from six healthy white volunteers were irradiated with Co-60 gamma rays and analyzed. The study found that whole hair strands, rather than ground samples, provided reliable ESR signals, unaffected by ambient humidity. A linear dose response model was established with a correlation coefficient greater than 0.9 for doses between 47 Gy and 370 Gy. However, the lowest detectable dose of 47 Gy was not statistically significant at the 95% confidence level. The study also developed a model for the decay of the ESR signal, noting that the rate of decay varied between samples, likely due to biological differences. It was concluded that samples should be analyzed within 24 hours or stored in liquid nitrogen to ensure accurate dose estimation, as the ESR signal diminishes over time.