ESR tooth enamel retrospective dosimetry quoted as spin numbers

Abstract Instead of using a set standard samples of irradiated tooth enamel, retrospective doses to tooth enamel can be estimated by ESR (electron spin resonance, or EPR) dosimetry with the spin numbers. The efficiency factor (the sensitivity to gamma ray dose) of the dosimetric CO2− ESR signal in tooth enamel was tentatively obtained, using a diluted tempol benzene solution, to be 8.73 × 1016 spin/J (spin/kg/Gy), being equivalent to a G value (a spin number formed per 100 eV of absorbed energy) of 1.40. When a dosimetric system in a laboratory is calibrated with a standard with known spin numbers such as tempol, retrospective ESR tooth enamel ESR dosimetry is done without a set of irradiated tooth enamel standard samples.