Radiation protection dosimetry最新文献

We simulated the mm-wave exposure of a real 60 GHz communication module and validated it using near-field measurements in terms of the incident power density. Next, we numerically evaluated the absorbed power density in a layered tissue model using the finite-difference time-domain technique. The worst-case and realistic exposures were compared with the latest guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and of the Institute of Electrical and Electronics Engineers (IEEE). The worst-case exposure complied with the exposure guidelines for a distance larger than 14.5 mm. Realistic exposure is application dependent and exceeded the limits specified by exposure guidelines for data-intensive applications with duty cycle of 90% at distances smaller than 10.6 mm.

A γ-ray calibration field using a sealed 133Ba source for photon energy in the 300-400 keV range was established at the Japan Atomic Energy Agency to evaluate radiation protection devices under low dose rate conditions. To suppress low-energy γ-ray components, a 2-mm lead filter was applied. The photon fluence spectrum was measured using a CdTe spectrometer and an unfolding method, yielding a spectrum with a mean energy of 321 keV. Reference air kerma rates were determined using ionization chambers calibrated in a 137Cs field, with energy correction factors applied. Spectrometry using a CeBr₃ scintillation spectrometer combined with the G(E) function method was employed to validate these corrections. Spectrum-averaged conversion coefficients were derived from the measured spectrum, indicating equivalence to the N-400 radiation quality. This field provided air kerma rates from 0.22 to 2.13 μGy h-1, suitable for testing devices used in environmental monitoring and nuclear emergency response.

This study investigated the seasonal variations of indoor radon concentrations in parts of cities across different climate zones of China. Using solid state nuclear track detectors (SSNTDs), radon measurements were conducted over a 12-month period in 171 dwellings located in 15 provincial capital cities. The annual average indoor radon concentration was 81 Bq m-3, with the highest mean level recorded in the Severe Cold Area (99 Bq m-3) and the lowest in the Hot Summer Warm Winter Area (52 Bq m-3). A consistent seasonal pattern was observed across all zones, characterized by elevated concentrations in autumn and winter and lower levels in spring and summer. The mean winter-to-summer concentration ratio was 1.68, indicating a declining trend compared to earlier data from 1994 in China. This trend may be attributed to changes in ventilation practices associated with the widespread adoption of air conditioning. Seasonal correction factors were determined for different climate zones, ranging from 0.80 to 1.43. This study highlights the seasonal fluctuations of indoor radon and the necessity of applying appropriate correction factors when estimating annual average radon concentrations based on short-term measurements to reduce assessment bias. The findings provide critical data and a methodological foundation for accurately assessing and seasonally correcting indoor radon concentrations under diverse climatic conditions in China.

This study aims to evaluate the uranium concentration as an indicator of internal exposure to assess its potential biological effects, including DNA fragmentation and oxidative stress. Blood samples were collected from 80 individuals (40 residents and 40 from the control group) in Jisr Diyala district, Iraq, for uranium measurements. DNA fragmentation and malondialdehyde (MDA) concentration were estimated using the comet assay and MDA assay, respectively. The uranium concentration in the blood was significantly higher (605.90 ng l-1) in the residents compared to that in the control group (367.04 ng l-1). DNA fragmentation showed a 1.8-fold longer DNA tail, 2.4-fold larger tail area, 2-fold higher %DNA in the tail, and 3.3-fold higher tail moment in the resident group than in the control group. The mean MDA concentration was higher in the resident group (1.250) than in the control group (0.698). A positive correlation was observed between uranium concentration, DNA tail length, DNA tail moment, and MDA concentration. Increased uranium levels underline the importance of studying the associated health risks and biological effects.

The aim of this study was to assess the impact of a state-of-the-art 32 cm axial field-of-view GE Omni Legend PET/CT system on administered activity and image quality, and to update Diagnostic Reference Levels (DRLs). System performance was evaluated using NEMA NU 2-2018 measurements and EARL2 accreditation tests. A comparison with the previous 5-ring GE Discovery IQ scanner was performed to analyze the administered activity, scan duration and image quality with and without Artificial Intelligence driven reconstruction. A retrospective analysis of standard-sized adult examinations was conducted to derive updated DRLs values. Omni Legend demonstrated improved sensitivity and Noise Equivalent Count Rate, enabling up to 60% reduction in injected activity while maintaining or improving image quality. Deep learning reconstruction enhanced image quality, particularly at lower administered activities. The DRLs were lower than the national and international reference levels, supporting dose optimization in clinical practice.

Monitoring radiation doses is critical for safety in nuclear medicine (NM) departments. This study assessed personal and ambient radiation doses during routine NM procedures and compliance with International Commission on Radiological Protection (ICRP) limits at the new NM department of Abu Ali Sina Hospital, Shiraz, Iran. Between March and April 2024, 500 procedures involving 99mTc and 131I were performed. Personal dose equivalents Hp(10), Hp(3), and Hp(0.07) were measured for staff using calibrated TLD-100 dosemeters. Ambient doses were monitored across the department. Measured doses included 11.19 mSv (fingers), 14.62 mSv (hands), 0.11 mSv (whole body), and 0.03 mSv (eye lens), with Technologist 2 showing the highest hand dose. Ambient monitoring showed the highest dose rate (1.19 μSv/h) in the waiting area near the hot lab, mainly from post-injection patients. While all doses remained within ICRP limits, the findings indicate the need for improved shielding and optimized workflow to minimize extremity and environmental exposure.

In recent years, more and more electronics have been exposed to the mixed radiation field. The radiation resistance of electronics has been paid more and more attention to and the China Spallation Neutron Source (CSNS) linac tunnel provides a natural mixed radiation field. One of the radiation hotspots induced by beam loss when the CSNS linac regularly operates is the debuncher component in the beamline. The radiation level around the debuncher was measured by dose monitors and simulated by the FLUKA code simultaneously. The results of measurement and simulation are consistent, which means that the model simulated by the FLUKA code is consistent with the actual situation. The energy spectrum of the mixed radiation field at CSNS was first simulated by the FLUKA code. The mixed radiation field is composed of charged and neutral hadrons (protons and neutrons), photons, and electrons over a range of energies. This radiation field is suitable for the radiation damage effect tests of electronic components operating in the mixed radiation environment, especially for the electronic components used in the accelerator tunnel.

Radiochromic films are a reliable tool for quantifying ultraviolet exposure dose. When used without modification, these films enable a simple, low-cost measurement of accumulated dose over time which is amenable to personal exposure monitoring. This study presents two methods to expand the utility of these films for dosimetry applications. One approach utilized an ultraviolet radiation attenuator to effectively extend the usable dose range of radiochromic films. The attenuators have the added advantage of obscuring the film from view so the color change of the film due to increasing exposure dose is not visible. The practical use of these films with attenuators over prolonged exposure periods is highlighted as a case study in this manuscript. A second modification is the addition of a structure to limit the dose received by the film to an 80° field of view. Limiting the field of view of the film dosemeter provides for an estimate of the dose received by the eyes, accounting for protection provided by the ocular cavity, and the use of a dosemeter with a restricted field of view is included in recommendations for commissioning of ultraviolet lighting installations. Radiochromic films, when used in conjunction with these tools, offer an effective solution for extended dose ranges and eye-specific ultraviolet dose measurement in indoor spaces utilizing germicidal ultraviolet technologies.

Californium neutron sources are fairly common and appreciated in ionizing radiation metrology. Due to the concomitant presence of different neutron-emitting radionuclides, the isotopic composition of the source ought to be known for an accurate estimation of neutrons emitted by the source in time. This becomes more important with the ageing of the source, because the 252Cf predominant contribution reduces in favour of other neutron-emitting radionuclides. This work illustrates a methodology to estimate the relative neutron emission of the most important nuclides. The advantage of the suggested approach lies in the use of a set of dose-rate measurements spanning several years, typically available at laboratories, since periodical checks of the field are performed. The method illustrated was applied to a californium source present at Paul Scherrer Institute calibration laboratory, yielding an estimation of the ratio of the neutrons emitted by 252Cf and 250Cf. Since for calibration laboratories any alteration of the neutron energy distribution emitted by the source could influence the response of detectors, available data on neutron spectra emitted by these nuclides have also been compared.

Clinical audits have been implemented in Finland to healthcare organizations over 20 years. We introduce the outcomes of fourth round external clinical audits on medical radiological procedures following the implementation of the EU Directive (Basic Safety Standards). We analyzed 31 external clinical audits on radiological practices in 2018-2022. The summarized strengths and recommendations from the audits were collected from the main auditing organization's database. 306 recommendations were given, 18% related to definitions of responsibilities, 16% to internal procedural guidelines, 16% to personnel education, and 25% to quality assurance and utilization of self-assessments of radiological procedures. Private and small organizations received less recommendations than large and public operators. Moreover, 215 strengths were reported, focusing on the clarity of responsibilities (21%) and excellence in quality assurance (15%). Reaching and maintaining feasible radiological diagnostic accuracy by consideration of radiation safety requires continuous quality assurance and development facilitated, and monitored by clinical audits.