Radiation protection dosimetry最新文献

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.

Limited data exists on radiation exposure to trauma and orthopaedic (T&O) surgeons using modern imaging equipment and personal protective equipment (PPE) in theatre. This study investigated radiation doses to the chest and axilla during routine orthopaedic trauma practice by issuing 189 T&O surgeons with two thermoluminescent dosemeters each (worn on chest and axilla) for a continuous 3-month period. Surgeons also completed a survey on demographics, radiation safety training, PPE type and availability to assess links with radiation doses. No surgeon received a total dose resulting in them exceeding the 20 mSv/year dose limit set by the UK Health and Safety Executive's Ionizing Radiation Regulations 2017. Radiation exposure was not significantly linked to demographics or training. 58.8% of surgeons had not received formal radiation safety training within the past 3 years, and 90% were not routinely dose monitored. National guidance on radiation safety training and behaviours would reduce variability and ensure workplace safety.

This study aimed to design and characterize a compressible phantom that simulates adipose, glandular, and mixed breast tissues for mammography applications. Samples were prepared using paraffin gel wax, silicone oil, glass microspheres, and silicone. The linear attenuation coefficients and effective atomic numbers calculated at 15 keV were 0.986 cm-1 and 5.97 for adipose tissue, 1.381 cm-1 and 7.81 for glandular tissue, and 1.772 cm-1 and 6.91 for the mixed sample. Densities and Young's modulus values obtained from computed tomography and compression tests were 0.89 g·cm-3 and 24.75 kPa for adipose, 0.98 g·cm-3 and 31.26 kPa for glandular, and 0.95 g·cm-3 and 26.27 kPa for the mixed composition. Mammographic images were satisfactory, and the calculated mean glandular dose values closely matched those extracted from Digital Imaging and Communications in Medicine (DICOM) headers, with mixed and glandular samples showing similar values to patient data. Slight deviations from previously published results suggest potential areas for further refinement of phantom properties.

This study compared radiation dose, vascular enhancement, and contrast-to-noise ratio (CNR) of 256-multidetector row computed tomography (MDCT) at 70 kVp with deep-learning reconstruction (DLR) to 64-MDCT at 80 kVp with ASiR of cardiac CT angiography (CCTA) in infants with congenital heart disease. The contrast medium (CM) was 266 mg/kg for the 256-MDCT group and 600 mg/kg for the 64-MDCT group. In the 256- and 64-MDCT groups, the median values were 0.45 and 0.75 mGy for adjusted volume CT dose index (P < .05) and 4.98 and 8.00 mGy-cm for dose length product (P < .05). Despite a 49% CM reduction in the 256-MDCT group, vascular enhancement and CNR showed no significant differences (P > .05). The 256-MDCT at 70 kVp with DLR can maintain vascular CT enhancement and CNR while reducing CM by 49% and radiation dose by 41% in infant CCTA, compared with 64-MDCT at 80 kVp with ASiR.

Children receive high radiation doses during interventional cardiology procedures and their sensitivity to radiation is higher than that of adults. A 4-year follow-up study was conducted in two large cardiovascular hospitals and a pediatric polyclinic with the objective of providing typical values. The median values of 454 cases obtained for fluoroscopy time, cumulative reference point air kerma (Ka,r) and air kerma-area product (PKA) by age range were 5.6 min, 53.6 mGy, and 4.1 Gy cm2 for <1 y; 4.3 min, 77.9 mGy, and 7.2 Gy cm2 for 1 to <5 y; 4.0 min, 41.4 mGy, and 7.4 Gy cm2 for 5 to <10 y; 4.4 min, 90.1 mGy, and 16.1 Gy cm2 for 10 to <16 y, respectively. The median values of 144 cases obtained for Ka,r and PKA by weight bands were 84.4 mGy and 7.4 Gy cm2 for <15 kg, 25.8 mGy and 3.7 Gy cm2 for 15-30 kg, 46.4 mGy and 9.2 Gy cm2 for 30-50 kg, and 154.0 mGy and 25.6 Gy·cm2 for >50 kg. Our results can serve as a dose comparison with local practice and as a basis for optimization between facilities.

Brain computed tomography (CT) is commonly performed in pediatric patients; however, radiation exposure to radiosensitive organs such as the lens and thyroid remains a major concern. This prospective study investigated the impact of gantry tilt on organ doses using thermoluminescent dosemeters. A total of 67 pediatric patients undergoing brain CT were divided into four age groups: 0-18 months, 18 months-5 y, 5-10 y, and 10-17 y. In vivo lens and thyroid doses were measured with and without gantry tilt, and their correlation with volume CT dose index (CTDIvol) was assessed. Significant positive correlations were observed between CTDIvol and both lens and thyroid doses. With gantry tilt, mean lens doses were 2.19-5.73 mGy and thyroid doses 0.68-0.99 mGy, compared with 10.89-29.30 mGy and 1.29-3.72 mGy, respectively, without tilt. Gantry tilt parallel to the supraorbital-meatal baseline substantially reduced organ doses, particularly to the lens, and should be considered as a practical optimisation technique in pediatric neuroimaging.

Examining occupational exposure to external ionizing radiation in radiotherapy facilities is crucial for evaluating regulatory compliance and technological progress. This study analysed exposure records for 158 workers at the Ocean Road Cancer Institute from 2019 to 2023, focusing on whole-body dose (Hp (10)) data. Over the 5-year period, radiotherapists, medical physicists, oncologists, nurses, engineers, nuclear medicine specialists, radiologists, and office attendants received an average effective dose of 0.60 ± 0.34 mSv, ranging from 0.1 to 1.3 mSv. The number of workers increased from 91 in 2019 to 158 in 2023. Doses exceeding 5 mSv represented only 8% of the total collective dose, with most individual doses remaining below 1 mSv. The annual average effective dose was below the global average, reflecting satisfactory radiation protection at the facility.

This study examined the levels of gamma-emitting natural radionuclides in soils from 11 paddy fields across Taiwan's primary rice-producing regions and assessed the potential radiological risk to farmers. The mean activities of 40K, 232Th, and 226Ra in the 66 soil samples were 591.0 ± 133.8, 45.4 ± 10.2, and 30.9 ± 6.6 Bq/kg, respectively, with variations among sites attributed to geological differences. The average activity ratios of 40K/226Ra (19.3) and 40K/232Th (13.1) were higher than global soil averages, suggesting a soil composition enriched in potassium-rich minerals, such as feldspar and mica. A strong positive correlation observed among 40K, 226Ra, and 232Th activities indicated a common geological origin. The radiological hazard was assessed by calculating the annual effective dose using the United Nations Scientific Committee on the Effects of Atomic Radiation (2010) methodology. The mean effective dose for farmers was estimated to be 46.5 ± 9.9 μSv/y, a value significantly below the public dose limit of 1000 μSv/y.