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EN
Background Thermoluminescent detectors, type MTS-6, containing isotope ⁶Li (lithium) are sensitive in the range of thermal neutron energy; the ²³⁹Pu-Be (plutonium-and-beryllium) source emits neutrons in the energy range from 1 to 11 MeV. These seemingly contradictory elements may be combined by using the paraffin moderator, a determined density of thermal neutrons in the paraffin block and a conversion coefficient neutron flux to kerma, not forgetting the simultaneous registration of the photon radiation inseparable from the companion neutron radiation. The main aim of this work is to present the idea of calibration of thermoluminescent detectors that consist of a ⁶Li isotope, by using ²³⁹Pu-Be neutron radiation source. Material and Methods In this work, MTS-6 and MTS-7 thermoluminescent detectors and a plutonium-and-beryllium (²³⁹Pu-Be) neutron source were used. Paraffin wax fills the block, acting as a moderator. The calibration idea was based on the determination of dose equivalent rate based on the average kerma rate calculated taking into account the empirically determined function describing the density of thermal neutron flux in the paraffin block and a conversion coefficient neutron flux to kerma. Results The calculated value of the thermal neutron flux density was 1817.5 neutrons/cm²/s and the average value of kerma rate determined on this basis amounted to 244 μGy/h, and the dose equivalent rate 610 μSv/h. The calculated value allowed for the assessment of the length of time of exposure of the detectors directly in the paraffin block. Conclusions The calibration coefficient for the used batch of detectors is (6.80±0.42)×10⁻⁷ Sv/impulse. Med Pr 2017;68(6):705–710
EN
Objectives While working with cyclotrons used for the production of radiopharmaceuticals, workers can experience significant exposure to the adverse effects of ionizing radiation. The aim of this paper was to determine the typical level of such exposure received by such personnel while servicing cyclotrons. Material and Methods Exposure was assessed using TLD detectors placed in an anthropomorphic phantom, as well as dose meter to determine whole body and eye lens exposure. The phantom was placed in locations receiving the greatest exposure to ionizing radiation during service activities. The time spent by employees during servicing was assessed based on routine visits by service technicians. The obtained results were compared with readings of detectors worn by employees during service activities. Results The highest equivalent doses in the thoracic area were found to be received by the lungs (211.16 μSv/year). In the head and neck area, the highest dose was measured in the eye lens (3410 μSv/year). The effective dose for the whole body was found to be 1154.4 μSv/year, based on the phantom, and 149 μSv per service visit (1192 μSv/year), based on the dose meters carried by the workers. Conclusions Service workers are exposed to significant doses of ionizing radiation, representing a clear radiological protection issue. To reduce exposure to eye lenses, it is recommended to use protective goggles when working with highly-radioactive elements.
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