Chyuzo Miyazawa

A close correlation between electron spin resonance (ESR) dosimetry from tooth enamel and cytogenetic dosimetry from lymphocytes of Hiroshima atomic-bomb survivors

PURPOSE To estimate gamma-ray doses received by Hiroshima atomic bomb survivors using electron spin resonance (ESR) of tooth enamel and to compare the results with cytogenetic data. MATERIALS AND METHODS Tooth enamel ESR was performed for 100 teeth donated from 69 Hiroshima survivors, and conventional cytogenetic examinations were conducted for 61 of the tooth donors. To evaluate possible contamination from dental X-ray exposure, which primarily affects the tooths buccal surface, each tooth was divided into buccal and lingual parts for subsequent independent enamel isolation and ESR measurement. RESULTS Almost 20 teeth showed considerably larger buccal doses than lingual doses, but most of these discrepant teeth were incisors and canines. The results are probably attributable to solar light exposure. In contrast, the buccal and lingual doses found in molars were similar. Conventional translocation data of lymphocytes and ESR-estimated doses of 40 donors of molars showed the dose-response for translocations to be almost the same as that expected from in vitro gamma-ray irradiation experiments. CONCLUSIONS Both tooth enamel ESR and lymphocyte cytogenetics are useful measures for individual biodosimetry of acute radiation exposure, even half a century after the exposure occurred.

Human tooth dosimetry for gamma-rays and dental x-rays using ESR

The effect of secondary electron equilibrium on the ESR dosimetry of x- and gamma-ray irradiation has been studied by using acrylic plates to simulate the soft tissue of the human mouth. Dental x-rays create a different ESR signal pattern at the front surface of the tooth vs the back surface. The effect on radiation build-up of the acrylic plate on gamma-irradiation is dominant at the front but is not appreciable at the back side of the tooth.

Dental ESR dosimetry of a medical physicist who received occupational radiation exposure for almost 40 Y.

Abstract— Dose distribution in the oral region of a medical physicist who received occupational radiation exposure for almost 40 y was determined retrospectively by electron spin resonance measurements of 24 tooth enamel samples using a calibration curve method. The result is considered to agree well with the value estimated from the record of his occupational exposure, including the measured values of personnel monitors. Doses to twelve of the above samples were determined by the additive re-irradiation method. The measured values obtained by the two methods agreed with the exception of one sample.