Radiation protection dosimetry最新文献

In this study, NaCl pellets read with optically stimulated luminescence were evaluated for their potential use as a point dosemeter in breast x-ray imaging. Dosimetry with NaCl pellets has previously been applied to various environmental and medical settings. NaCl pellets have potential in clinical breast dosimetry because they can enable multiple point measurements to be simultaneously conducted in a cost- and time-efficient manner. Using two digital mammography imaging systems, the air kerma response of the NaCl pellets for a standard breast setup was investigated. The air kerma response was observed to be linear, and mathematical fits were successfully used to estimate the cumulative incident air kerma during digital breast tomosynthesis. Deviations from a reference digital dosemeter were 6% and 8% for the two mammography systems, respectively. Measurements conducted at different angles of exposure showed that the NaCl pellets had no angular dependency in the range ± 15°. Finally, the uniformity of the beams was confirmed to avoid possible errors due to the uncertainty of the dosemeters' positions in the exposure field.

A mobile gamma spectrometer's series of pulse height distributions (gamma spectra) acquired when passing a point source contains enough information to derive the distance to the source, its shielding and activity. Two Excel routines, SODAC and SSC, have been developed to determine these source parameters. SODAC determines the source-road distance by finding the best fit of the measured series of the primary photon peak count rates to a count rate function characteristic of the distance to the source. A possible source shield reduces the primary count rate and raises the count rate from Compton scattered photons in the shield. SSC calculates the shield mass thickness for common building material using ratio functions of scattered to primary count rates obtained from measurements on known shielding geometries. SODAC then calculates the source activity. The technique was practically tested for 137Cs point sources but can also be applied to other gamma-emitting radionuclides.

The Nordic Society for Radiation Protection (NSFS) was founded in 1964 at the initiative of Rolf Sievert. Its task is to activate the exchange of knowledge and experience in the Nordic countries regarding protection against ionizing and non-ionizing radiation, for all kinds of occupational, medical, or public exposures. NSFS has always included members from all five Nordic countries and was a founding member of IRPA, the International Radiation Protection Association. Since 1966, NSFS has had regular meetings at 3- or 4-year intervals, in turn in each of the Nordic countries. In addition, NSFS has arranged various themed meetings. The meetings of the Society have been informal and collaborative and important for transfer of skills between generations. The activities have stimulated Nordic co-operation regarding nuclear safety research, nuclear waste, radioecology, medical radiology, and clinical physics, as well as Nordic postgraduate courses. NSFS lives up to the IRPA motto of being the international voice of the RP profession.

Carbon-14 often dominates the effective dose to the public from authorized discharges from Swedish nuclear power plants (NPPs). In contrast to air-borne releases, water-borne discharges of 14C are currently not routinely monitored at Swedish NPPs. We have measured 14C in Fucus spp. (brown algae, used as bioindicators of 14C) in shallow waters at the Swedish west coast from 2020 to 2024. At Ringhals NPP, 14C in Fucus spp. was up to ~50 per cent higher than at nearby marine reference sites and was also higher than observed in the nearby terrestrial environment. The local marine environment of Ringhals NPP showed high spatial and temporal variability in 14C. Carbon-14 in Fucus spp. was generally higher in Skagerrak than in the more southernly Kattegat, likely mainly due to influence from discharges from the spent nuclear fuel reprocessing plant in La Hague in France and from its counterpart in Sellafield in the UK.

There has been an increase in the activities of naval nuclear-powered vessels in the High North and vessels carrying radioactive waste along the Norwegian coastline. Previously, there have been incidents with such vessels in the sea area near Norway, which also require emergency handling from the Norwegian authorities. This article gives some examples of historical events that have been particularly interesting. The incidents include reactor or cooling system failures, fires and the actions of crews.

A field survey was conducted in Sweden with the purpose to revisit the ground deposition of Chornobyl 137Cs and the associated ambient dose equivalent rate, H* (10), at various measuring locations in the Gävle and Älvkarleby municipalities. The specific purpose was to compare the 137Cs deposition values as measured in situ using a field portable gamma spectrometer [3″(Ø) × 3″ NaI(Tl)-crystal] with the ex situ estimates obtained from gamma spectrometry of soil cores taken at the measuring locations. An additional purpose was to re-assess the effective ecological half-times of the Cs-contribution to the H* (10) and compare with a previous assessment done for data until 2013. The results show that ex-situ soil sample data exceed the 137Cs deposition values from the field portable NaI(Tl) gamma spectrometer by, on average, 50%. The discrepancy could mainly attributed to the difference between the actual field-of-view seen by the portable device at 1 m above ground compared with the calibration geometry of an infinite planar surface with a Cs ground penetration at 3 g cm-2. The H* (10) measurements collected in 2022 could indicate that the effective ecological half-time of 137Cs attributed ambient dose equivalent rate in the area ranges between 10 and 20 y instead of the 6.8 y obtained from the previous assessment of data between 1987 and 2013. The findings demonstrate, however, the usability of the portable field gamma spectrometer when used to characterize the long-term time dynamics of external doses from 137Cs in cases where the 137Cs dose contribution is well below normal background levels.

In vivo preclinical X-ray micro-computed tomography (μCT) imaging is widely used to obtain three-dimensional anatomical information of small animals. However, the potential for radiation exposure to influence experimental outcomes necessitates accurate dose estimation. The aim of this study was to develop a robust and reproducible method for estimating and evaluating absorbed doses in small animals undergoing preclinical in vivo μCT imaging. Absorbed doses were measured at four separate positions within a dedicated polymethyl methacrylate phantom using MCP-N (LiF, Cu, P) thermoluminescence dosemeters (TLDs) and a novel type of optically stimulated luminescence dosemeter (OSLD) made from household salt (NaCl). The findings were benchmarked against the vendor's absorbed dose estimates, revealing a discrepancy between the measured and provided values. The results for the OSLDs followed a similar trend to the TLDs, though significant statistical differences were found between the luminescent dosemeters and the vendor values. In this study, a method for measuring the absorbed doses from μCT systems was presented. The results indicate a need for thorough dose measurements prior to performing longitudinal imaging studies.

Samples of Fucus serratus and Fucus vesiculosus have been regularly collected at Särdal (56.76 N, 12.63E) on the Swedish west coast since 1967, for most of the time, every two months. In 2020, sampling of Fucus spp. was extended to 44 other locations along the Swedish west, south, and east coast for comparison with Särdal data. At seven of these locations, water samples and extra samples of Fucus spp. were also taken for 3H analysis. Measurements have been performed by gamma spectrometry, or by radiochemical separation followed by low background beta measurements, alpha spectrometry or accelerator mass spectrometry. Time variations of the measured concentrations of various radionuclides (3H, 14C, 60Co, 99Tc, 129I, 131I, 134Cs, 137Cs, 236U, 238U, 239Pu, and 240Pu) are reported. The concentrations have been correlated with emissions from the nuclear fuel reprocessing facilities at Sellafield (UK) and La Hague (France). Contributions from the nuclear power plants in Ringhals and Barsebäck have also been identified, as has fallout from Chernobyl still stored mainly in the sediments and water of the Baltic Sea. In recent decades, studies have shown increasing levels of 129I and 236U and decreases in 137Cs, 99Tc, and 239 + 240Pu concentrations over time. The 14C analyses show an impact of anthropogenic 14C from activities other than atmospheric nuclear weapons tests in the 1950s and 1960s. The considerable variation in the concentration of different radionuclides over time and along the coasts warrants further studies to determine the possible origin of these radionuclides and to map background data in the event of future releases.

The Swedish Radiation Safety Authority has presented a report on severe accident scenarios at the European Spallation Source (ESS) for dimensioning the emergency preparedness zones around the facility. The source-term in the scenario consisted of more than 80 tungsten-target spallation products with physical half-life (T½) exceeding 1 hour. The purpose of this study is to establish which of these radionuclides will become of highest importance in terms of the radiological consequences to residents in areas affected by an accident release. In analogy with accidents at nuclear power plants, where the fission product 137Cs is a key nuclide for estimating projected external doses to affected residents, a corresponding key nuclide for ESS is required for the emergency preparedness. Using existing accident source terms in combination with reported values on ecological half-times of the gamma emitter 137Cs, the external dose rates and cumulative doses per unit initial ground deposition of the suggested key-nuclide (182Ta) could be estimated. In terms of 50 y dose from a dry deposition of the released source-term, 172Lu (T½ = 6.7 d, supported by 172Hf with T½ = 1.87 y) contributes up to 50% of the 50 y dose, depending on the ecological half-times for the element. The isomer 178nHf (T½ = 31 y) is the second largest contributor to gamma-ray dose, followed by 182Ta (T½ = 115 d), that contribute with about 15% and 10% of the 50 y dose, respectively. The results thus suggest that 172Hf/172Lu may be more suitable for long-term follow-up of projected doses from accidental ESS releases than 182Ta.

This study evaluates the dosimetric performance of GD-302M radiophotoluminescent glass dosemeters (RPLGDs) under high-energy X-rays (6-15 MV) as a potential alternative to thermoluminescent dosemeters for radiotherapy audits in China. Key properties-dose linearity, uniformity, reproducibility, energy response, fading, build-up effects, and signal depletion-were systematically assessed using a medical linear accelerator under reference conditions. The results demonstrated excellent dose linearity (R2 = 0.9987, 1-4 Gy), uniformity (coefficient of variation = 0.9%), and reproducibility (standard deviation = 0.42%). Energy-dependent variations remained within 1.3%, while fading effects showed a cumulative signal loss of 3% over 110 d. Unpreheated RPLGDs retained 98% of preheated signals after 30 d, with minimal signal depletion per readout (0.016%). A water-to-solid phantom conversion coefficient of 0.998 was established. The total experimental uncertainty was 2.4%. These findings validate RPLGDs as a stable, reproducible, and cost-effective tool for enhancing radiotherapy quality assurance in resource-constrained settings.