Assessment of 90Sr concentration in dental tissue using thin-layer beta-particle detectors and verification with numerical calculations.

Electron paramagnetic resonance (EPR) measurements of tooth enamel can be used as an individual biological dosimeter for external dose assessment. However, the presence of 90Sr in the tooth tissues makes the task of interpreting EPR tooth dosimetry more complicated. The determination of the dose contribution of incorporated 90Sr in calcified tissue to the total dose measured by EPR is one of the main aspects of correct interpretation of EPR tooth dosimetry. In this work, experimental and numerical calculations were performed to convert the measured beta-particle dose rate to 90Sr concentration in calcified tissue. The cumulative beta-particle dose was measured by exposing artificially contaminated dentin and enamel to thin-layer alpha-Al2O3:C detectors in two different exposure geometries. Numerical calculations were performed for experimental exposure conditions using calculations of electron transport and secondary photons [Monte Carlo n-Particle Transport code version 4C2 (MCNP)]. Numerical calculations were performed to optimize the sample size and exposure geometry. The applicability of two different exposure conditions to be used in routine analysis was tested. Comparison of the computational and experimental results demonstrated very good agreement.