B. Ciesielski

The second international intercomparison on EPR tooth dosimetry

Eighteen international EPR laboratories participated in the second intercomparison programme. Each participant had to prepare enamel samples and evaluate the absorbed dose from molars that were irradiated in vitro in the range 0-1000 mGy. The objective of the programme was to bring together all methods which are currently applied by different laboratories for EPR dose reconstruction and to demonstrate the present state of dosimetry. An overview of the essential features of the different methods is presented. The current accuracy of EPR tooth enamel dosimetry under defined conditions of irradiation is evaluated

EPR dosimetry in nails—A review

ABSTRACT Electron paramagnetic resonance (EPR) biodosimetry is based on quantitative measurements of the effects of radiation in biological materials. These effects have a form of stable free radicals and the concentration of these radicals is dependent on the absorbed dose. Recent studies suggest a possibility of using EPR signals generated by ionizing radiation in nails for radiation dosimetry. This article provides a critical review of reported measurement procedures and methods used to relate quantitative features of the measured spectra with the absorbed dose. The preliminary part of this article gives basic information about the structure and composition of nails and contains a brief description of the history of the use of EPR spectroscopy in determining the doses absorbed by irradiated persons. The main part of the article provides characterization of EPR signals generated by mechanical cutting of nails and by radiation and presents factors responsible for the magnitude and changes in these signals. Practical applications of EPR dosimetry in nails in reconstruction of doses absorbed by victims of radiation accidents are addressed. In the final part of the article prospective future research in the field of EPR dosimetry in nails is discussed.

The effect of dose and water treatment on EPR signals in irradiated fingernails

Fast and precise retrospective dosimetry is crucial in making decisions about medical procedures and safety measures in radiation accidents. Electron paramagnetic resonance (EPR) spectroscopy has a potential as one of available biodosimetry methods for use in victims of such incidents. In this study, authors present the findings on EPR dosimetry in fingernails. Authors describe changes of EPR signals in unirradiated and irradiated nails in time after cutting and the effect of water on the mechanically induced and radiation-induced EPR signals measured ex vivo in the fingernails. The effect of dose on amplitude of the EPR signal was measured in nails that were soaked for 10 min in water after their irradiation. The obtained dose-response curves, which reflect changes in concentration of the radiation-induced RIS5 radicals, reach their maximum for doses of 40-60 Gy.

Application of EPR dosimetry in bone for ex vivo measurements of doses in radiotherapy patients

In the present study, bone samples from three patients treated in radiotherapy facilities in Poland were used for the determination of doses absorbed during radiotherapy. The samples were obtained during surgical treatments of patients performed due to medical indications. For the purpose of retrospective dosimetry, sensitivity of the radiation-induced EPR signal was individually calibrated in the samples by re-irradiation of the samples with known doses. The doses reconstructed in bones extracted within 6 months after irradiation were consistent with those calculated by treatment planning systems. The dose reconstructed in the bone removed 6 y after radiotherapy was ∼14% lower than the calculated one.

Effects of water treatment and sample granularity on radiation sensitivity and stability of EPR signals in X-ray irradiated bone samples

The article describes effects of sample conditions during its irradiation and electron paramagnetic resonance (EPR) measurements on the background (BG) and dosimetric EPR signals in bone. Intensity of the BG signal increased up to two to three times after crushing of bone to sub-millimetre grains. Immersion of samples in water caused about 50 % drop in intensity of the BG component followed by its regrowth in 1-2 months. Irradiation of bone samples produced an axial dosimetric EPR signal (radiation-induced signal) attributed to hydroxyapatite component of bone. This signal was stable and was not affected by water. In samples irradiated in dry conditions, EPR signal similar to the native BG was also generated by radiation. In samples irradiated in wet conditions, this BG-like component was initially much smaller than in bone irradiated as dry, but increased in time, reaching similar levels as in dry-irradiated samples. It is concluded that accuracy of EPR dosimetry in bones can be improved, if calibration of the samples is done by their irradiations in wet conditions.