[Pharmacokinetic and dosimetric characteristics of new radiopharmaceutical based on complexes of 103Pd and albumin microspheres].

Results of the study of absorbed dose formed in organs and tissues of mice after administration of new therapeutic radiopharmaceutical on the base of 103Pd and albumin microspheres (MSA) are presented. Pharmacokinetic parameters of preparation distribution in the body of animals were experimentally determined and then absorbed doses were calculated using MCNP code for the developed mathematical model of mouse. It was shown that absorption of 103Pd-MSA in tumor, physical properties of 103Pd and daughter radionuclide 103mRh provide a targeted irradiation of tumor as compared with the adjusting tissues and critical organs. In administration to tumor muscle tissue of the leg of experimental animals after 15 days following the injection of 103Pd-MSA the accumulated absorbed dose was 15 times less than corresponding one in tumor. In a critical organ (kidneys) the accumulated absorbed dose was 20 times less than in tumor. The work performed as a stage of pre-clinical testing of the radiopharmaceutical.

Calibration of EPR signal dose response of tooth enamel to photons: experiment and Monte Carlo simulation.

The experimental energy dependence of the electron paramagnetic resonance (EPR) radiation-induced signal at irradiation by photons in the energy range of 13 keV-1.25 MeV was analysed in terms of the absorbed dose in human tooth enamel. The latter was calculated using a Monte Carlo simulation of the photon and electron transport. The dependence of the calculated absorbed dose on the sample thickness was analysed. No energy dependence of the EPR signal on the absorbed dose in enamel was verified in the range of 37 keV-1.25 MeV. At 13 and 20 keV the EPR signal dose response was reduced by 8% probably due to sample powdering. Dose-depth profiles in enamel samples irradiated by 1.25 MeV photons in polymethylmethacrylate and aluminium build-up materials were calculated. It was concluded that secondary electron equilibrium conditions are better fulfilled for irradiation in aluminium, which makes this material preferable for calibration.

Dose reconstruction by EPR spectroscopy of tooth enamel: application to the population of Zaborie village exposed to high radioactive contamination after the Chernobyl accident.

Individual irradiation doses were determined by electron paramagnetic resonance spectroscopy of the tooth enamel of the inhabitants of Zaborie, the most contaminated inhabited settlement not evacuated after the Chernobyl accident. Dose determination was performed using a specially developed automatic spectrum processing procedure. Spectrum processing was carried out in different operating modes, and average results were taken in order to reduce the contribution of uncertainty in dose determination caused by spectrum processing. The absorbed doses determined in enamel were corrected to take into account the contribution of natural background radiation and to determine the individual excess dose due to radioactive contamination of the territory. Individual excess doses are compared to calculated individualized doses to teeth, estimated using the local radioactive contamination levels, dose rates, and information concerning individual behavior. The individual excess doses measured by electron paramagnetic resonance spectroscopy and the calculated individualized doses are fully independent. Mean square variation between results of two methods was found to be 34 mGy, which is consistent with error estimation for both methods. This result can validate both the methodology of signal processing presented here when using electron paramagnetic resonance dosimetry of tooth enamel for low doses and the methodology of individualized dose calculation.