The development of sustainable and lead-free shielding materials is of increasing interest for diagnostic radiology facilities, particularly in low- and middle-income countries where cost, material availability, and environmental considerations are important factors. This study evaluates the radiation shielding performance of fired clay bricks (FCB), concrete, and stainless steel (SS) as alternative structural materials for X-ray facilities operating up to 150 kVp using Monte Carlo simulations with the PHITS code. Mass attenuation coefficients and effective atomic numbers were computed to characterize photon attenuation properties and guide the design of multilayer shielding assemblies. Two concrete-encapsulated assemblies were engineered: a standard composite (C8-FCB200-C8, 2.32 mm lead equivalent) and a steel-reinforced composite (SS2-C8-FCB200-C8, 2.73 lead equivalent). Their performance was benchmarked against a conventional 2 mm lead barrier. Photon flux distributions and effective dose rates (EDR) were evaluated at primary (Cell 20) and secondary (Cells 22, 24, 26) shielding boundaries for X-ray tube potentials ranging from 80 to 150 kVp. At 150 kVp, the lead reference barrier reduced the transmitted EDR to 7.09E-09 µSv/h at the primary barrier and below 1.79E-12 µSv/h at the secondary barriers. A comparative analysis of the EDR recorded behind the alternative barriers reveals that for the secondary barriers, the standard C8-FCB200-C8 configuration was fully adequate across the entire investigated tube voltage range (80 to 150 kVp). Conversely, for the primary barrier, the reinforced SS6-C8-FCB200-C8 composite is strictly required to provide sufficient shielding at 150 kVp. These results demonstrate the potential of locally available, lead-free composite materials as cost-effective and environmentally sustainable alternatives for radiation shielding in diagnostic radiology facilities while supporting optimisation and ALARA principles.
Consumer electronic radon monitors (ERMs) are increasingly used for residential screening, yet long-term field evaluations under real-world conditions remain limited. This study conducted a 98day collocation of 15 models of ERMs (3 units each; 45 total) alongside a calibrated research-grade reference instrument (AlphaGuard PQ2000) and two alpha-track detectors (Radtrak 3 ; Radonova) in the lowest lived-in space of an occupied single-family home in Waterloo, Ontario, Canada, while concurrently recording environmental parameters, including PM2.5, CO2, temperature, and relative humidity. The average radon concentration reported by the reference instrument was 99 Bq/m 3 , with a range from 62 -141 Bq/m 3 . The cumulative and real-time ERM performance was assessed using a variety of metrics. Performance varied substantially across and within models. Eight out of the fifteen models had two or more units that achieved a relative percent error (RPE) within ±25%, with the top performers achieving an RPE of 3-5% after 13 weeks of deployment, while several other devices under-or overestimated, from negative 47% to positive 220%. Most models showed acceptable intra-model repeatability with a coefficient of variation lower than 15%. For real-time performance, top-performing ERMs achieved Root Mean Square Error of 5 -6 Bq/m 3 , and moderate (ρ = 0.70 -0.77), statistically significant Spearman-rank correlations on two-day non-overlapping averages. Overall, selected ERMs can approximate long-term cumulative average concentrations under real-world conditions, making them appropriate for long-term radon risk screening. However, the variability in ERM performance also highlights the need for regulatory oversight and independent testing to protect building occupants from a false sense of security or false alarms.
This study quantified the activity concentrations of 226Ra, 228Ra, 40K, and the anthropogenic 137Cs in coffee and fresh produce from southeastern Brazil and assessed the associated ingestion dose to consumers.
Seventeen coffee samples and 27 fresh-produce items were collected from four municipalities representing distinct geological settings: Itatiaia and Rio de Janeiro (Rio de Janeiro state), and Poços de Caldas and Mariana (Minas Gerais state). Activity concentrations were determined by high-purity germanium (HPGe) gamma-ray spectrometry. Annual effective doses (E) and the Excess Lifetime Cancer Risk (ELCR) were calculated using consumption data from the Brazilian Household Budget Survey (IBGE) and dose coefficients from ICRP Publication 119.
Coffee showed mean activity concentrations of 563 ± 26 Bq/kg (40K), 3.7 ± 0.6 Bq/kg (228Ra), and 1.4 ± 0.2 Bq/kg (226Ra), with a mean annual effective dose of 3.2E-02 mSv/year. Fresh produce exhibited marked regional variability, most notably for 228Ra: carrots from Itatiaia reached 27 ± 1.9 Bq/kg, nearly an order of magnitude above those from Poços de Caldas (3.3 ± 0.5 Bq/kg). 137Cs was below the detection limit in all samples, indicating negligible anthropogenic contamination.
All individual annual effective doses represented a negligible fraction of the 1 mSv/year public dose criterion recommended by the ICRP. The highest individual values were observed for cassava from Mariana (1E-02 mSv/year), followed by papaya (Mariana) and orange (Itatiaia) at 9E-03 mSv/year each, and onion from Poços de Caldas (6E-03 mSv/year). Cumulative annual effective doses obtained by summing all analyzed fresh-produce items were 5.9E-02 mSv/year (Itatiaia), 2.2E-02 mSv/year (Poços de Caldas), and 6.3E-02 mSv/year (Mariana); combined with the mean coffee dose (3.2E-02 mSv/year), the total remained below 1.0E-01 mSv/year (<10% of the criterion). ELCR values for individual items ranged from 4E-07 to 4E-05. For reference, the global average ingestion dose from natural radionuclides is approximately 0.29 mSv/year (UNSCEAR, 2000).
Diagnostic reference levels (DRLs) guide dose optimisation, yet paediatric computed tomography (CT) DRLs remain scarce, heterogeneous, largely anatomy-based. This study aimed to establish local paediatric DRLs for head, chest, and abdomen-pelvis CT according to European guidelines, compare them with European DRLs, and assess the feasibility of indication-based DRLs. This single-institution study included 604 of 829 CT acquisitions performed in children aged ⩽16 years in 2017 or 2022. DRLs, defined as the 75th percentiles of volumetric CT dose index (CTDIvol) and dose length product, were derived by age for head CT and by weight for body CT. Indication-based DRLs were explored for five indications. Local DRLs were compared with European and other recent values using 95% confidence intervals. Quantile regression was used to estimate DRL curves and identify predictors for cervical spine CT dose. Head CT DRLs were up to 33% lower than European levels (p< 0.05), and abdomen-pelvis CT DRLs up to 44% lower (p< 0.05), while chest CT DRLs did not differ significantly (p> 0.05). Compared with recent studies, head CT DRLs were lower (p< 0.05), whereas chest and abdomen-pelvis CT DRLs were higher for some groups. Higher doses were observed with older scanner. DRLs for craniosynostosis and chronic sinusitis CT were tenfold lower than those for head trauma or stroke CT. For cervical spine CT, weight was a stronger predictor of CTDIvol than age (pseudoR2= 0.72 vs 0.54). In conclusion, paediatric CT DRLs can be established at institutional level in accordance with European guidelines. The observed DRLs suggest successful implementation of optimisation strategies for head, whereas chest and abdomen-pelvis CT may offer further optimisation potential. Latest-generation scanners and paediatric protocols across the paediatric spectrum should be standard practice, and greater emphasis on indication-based DRLs can enable more precise and clinically relevant optimisation. Weight-based stratification is recommended for cervical spine CT DRLs.
Monte Carlo simulation of secondary neutron and photon dosimetry-specifically the ambient dose equivalent H*(10)-is central to radiation protection in pencil-beam scanning (PBS) proton therapy. We report particle and heavy ion transport code system (PHITS) version 3.35 calculations of H*(10) for proton beams from 70 to 250MeV incident on a water phantom representative of the Ion Beam Applications Blue Phantom, scored at 11 emission angles at 80 cm using International Commission on Radiological Protection Publication 74 fluence-to-dose conversion coefficients. Results are normalised to peak absorbed dose, yielding the quantity H*(10)/D [nSv Gy-1] relevant to facility shielding and patient out-of-field dose estimation. The distal Bragg-peak range R80 was benchmarked against independent Geant4/Gate calculations, agreeing within -0.56% to -3.61% and meeting the ±3% clinical criterion for energies⩾ 100MeV. Enabling the low-energy neutron event-generator mode changed secondary-neutron yields by less than 0.2%, indicating that default settings are adequate for these radiation-protection estimates. The H*(10)/D angular distribution showed a forward maximum near 40° and a backward maximum at 180°; the forward-to-lateral ratio H*(40°)/H*(90°) rose from 1.1 at 70 MeV to 2.5 at 250MeV-the forward peak becoming the global maximum above 150 MeV-while neutrons exceeded photons at 90° by factors of 22.9-56.2. A representative PBS nozzle model was added to quantify the effect of beam-line components; the simulated forward energy dependence and neutron spectral composition agree with published pencil-beam-scanning measurements, while absolute magnitudes remain lower owing to the single-pencil bare-phantom geometry. For a 150 MeV spread-out Bragg peak, H*(10)/D was 4.8-6.2× higher than the monoenergetic beam, reflecting the larger number of protons required per unit dose. The dose-normalised dataset provides a systematic, practical reference for PHITS users in proton therapy radiation protection.
Medical radiation workers constitute the largest occupational group exposed to man-made ionising radiation, yet much of the evidence on cancer risk derives from early high-dose practice eras that differ substantially from contemporary conditions. This narrative review synthesises evidence from cohort studies of medical radiation workers across occupational exposure eras, with emphasis on epidemiologic approaches, observed cancer risk patterns, and sex-specific differences. Epidemiologic methods have evolved from proxy-based exposure indicators to quantitative dose-response modelling using excess relative risk, supported by improved dosimetry and organ-dose reconstruction. Early high-dose cohorts consistently demonstrate elevated risks for radiosensitive cancers, including breast cancer, haematopoietic malignancies, and non-melanoma skin cancer. In contrast, contemporary cohorts exposed under current protection standards accumulate low cumulative doses and show small, often non-significant dose-response estimates with wide confidence intervals. These findings reflect both reductions in occupational exposure and the limited statistical power of epidemiologic studies at low dose levels, where excess risks are difficult to detect and dose-response shape cannot be clearly distinguished. Available evidence does not indicate consistent sex-based differences in radiation-related cancer risk at occupational exposure levels. Overall, while advances in dosimetry have improved exposure assessment, the ability to quantify cancer risk under contemporary low-dose conditions remains constrained. The findings support the effectiveness of current radiation protection practices while highlighting persistent uncertainty in estimating risks at low occupational doses.
This study investigates how much the conventional quantity value (true value) of the operational quantityHp(3), defined in International Commission on Radiation Units and Measurements (ICRU) 47 and 51, changes for oblique radiation incidence when a rotation around the horizontal instead of the commonly used vertical axis of the cylinder phantom is performed. For this, conversion coefficientshpK(3) andhpD(3), for photons and betas, respectively, were calculated for both vertical (usual) and horizontal rotations of the cylinder phantom for mono-energetic photons from 2 keV to 10 MeV and for reference beta-particle fields with mean energies from 0.54 MeV to 1.2 MeV (and maximum beta energies from 1.4 MeV to 3.3 MeV). From the results, the ratio of the values for horizontal and vertical rotations were determined. To complement these, the corresponding ratios for the protection quantity equivalent dose to the lens of the eye,Hlens, defined in International Commission on Radiological Protection 116, were calculated and compared with the results forHp(3). For photon fields most relevant in lens monitoring, i.e. especially in interventional radiology, it turned out thatHp(3) is only slightly (up to ∼10%) smaller when rotating around a horizontal instead of the commonly used vertical axis. Larger differences only occur for small photon energies (below ∼20 keV) and large angles of radiation incidence (75°) whereHp(3) is reduced to practically zero for a horizontal rotation compared to the normal (vertical) rotation. For reference beta-particle fields, the differences between vertical and horizontal rotations are also mostly below 10% - due to the rather broad angular distribution of the beta fields resulting in only small differences of the 'effective' path length in the cylinder phantom. In contrast, the differences of the dose to the lens of the eye,Hlens, are rather large for both photons and betas and always significantly larger than forHp(3). From the author's point of view, these findings do not impose the necessity to update theHp(3) by distinguishing between the (usual) vertical and a horizontal rotation axis. Nevertheless, the data presented may serve ICRU to judge whether an updated definition of the operational quantityHp(3) should be considered. If so, International Standardization Organization needs to provideHp(3) values for horizontal rotations of the cylinder phantom for reference radiation fields and International Electrotechnical Commission needs to extend their dosemeter type-test procedures to horizontal rotations.
Backscatter factor (BSF) is a critical correction parameter in radiation dosimetry, accounting for dose enhancement due to photon scattering within irradiated media; however, systematic evaluations beyond the ISO slab phantom remain limited. In this work, BSFs were comprehensively estimated for all ISO-recommended phantoms-slab, cylindrical, pillar, and rod-over a photon energy range of 10 keV-2 MeV and multiple field sizes using the FLUKA Monte Carlo code with an air-kerma-based formalism. The results show a strong coupled dependence of BSF on photon energy and beam size, with a characteristic peak in the intermediate energy range (∼40-80 keV) and geometry-driven variations and field-size sensitivity-maximized in the slab phantom and minimized in the rod due to scattering volume constraints, while cylindrical and pillar phantoms exhibit intermediate behaviour. To extend these results to realistic irradiation conditions, a Python-based standalone tool was developed using PCHIP interpolation and fluence-weighted averaging to compute spectrum-averaged BSFs for ISO 4037 beams, diagnostic and therapeutic spectra, and user-defined spectra, demonstrating deviation within 0%-2.3% with published data. The study provides a BSF dataset across all ISO phantoms along with a validated computational framework, enabling improved accuracy in dosimeter calibration and determination of operational quantities such asHp(3) andHp(0.07). The Python-based standalone executable of the BSF software, compatible with both Windows and Linux platforms, along with its complete source code, is provided as open-access supplementary data.
Accurate estimation of external radiation exposure is essential in nuclear medicine (NM) for occupational safety and regulatory compliance. Point-source models are widely used because they are simple and require limited input data; however, their accuracy can degrade when radioactive material is distributed over extended line, surface, or volume geometries. This study evaluates point-source approximation error across a range of extended-source models, beginning with non-attenuating line and disc geometries and extending to attenuating finite-thickness slab and laterally viewed cylindrical volume sources. Absolute dose-rate examples were calculated using a Tc-99 m gamma constant, while relative error and correction-factor results were expressed using geometry- and attenuation-dependent parameters. For non-attenuating line and disc sources, point-source approximations can overestimate exposure by up to approximately 100% when source dimensions exceed the exposure distance. A practical threshold was identified: when the source dimension-to-distance ratio is less than one, point-source errors remain below 5%; above a ratio of 1, line or disc models should be considered or the point-source estimate corrected using the factors provided. For attenuating finite-thickness slab sources, an analytical correction factor was derived that separates into a lateral-extent term governed by the source diameter-to-distance ratio, and an attenuation-thickness term governed by. Together, these two dimensionless parameters allow point-source error to be mapped across combinations of source size, distance, attenuation coefficient and slab thickness. For laterally viewed cylindrical sources, kernel-based volume integration showed that point-source error depended jointly on,and, whereis the surface-to-point distance. The 20% error region narrowed markedly as, indicating that patient-scale attenuating cylinders cannot be assessed from distance alone. Representative Tc-99 m examples showed modest error for a 5 ml syringe-scale cylinder at 1 m, but substantial overestimation for a patient-torso-scale cylinder. Comparison with published measured patient dose-rate studies showed that the patient-torso cylindrical model produced values of a similar order of magnitude to measured 1 m patient dose rates, whereas point-source estimates were generally higher. This paper provides practical correction factors, error-threshold maps and model-selection guidance to support more appropriate selection of source models in NM exposure assessments.
At CERN the maintenance and dismantling of high-energy particle accelerators generate waste that is potentially radioactive. When activity levels are negligible, waste can be released from regulatory control through clearance procedures. However, radiological characterisation is challenging due to the diversity of activation scenarios, radionuclide inventories, and material compositions. We address this complexity by developing a data-driven probabilistic approach that combines activation simulations with classical machine learning. This study applies the method to irradiated electric cables, with a particular focus on defining threshold values for measurable quantities (activity, dose rate, and mass) that determine clearance eligibility. The proposed method offers operational advantages by simplifying measurement and decision-making procedures and is consistent with international guidance on clearance.
In the area of research on electromagnetic fields (EMFs) and health, decision makers and practitioners face an increasingly complex information landscape, characterised by high publication volumes, heterogeneous methods and the occasional spread of oversimplified claims. 'Spotlight on EMF Research', offered by the German Federal Office for Radiation Protection (BfS), wants to support the EMF-interested community by providing regular, structured assessments of selected scientific publications.Spotlight on EMF Researchoffers concise summaries and critical commentaries, brief Literature Suggestions, comprehensive literature lists, and a quarterly newsletter aimed at regulators, advisory bodies, scientists, and other expert users. This article describes the underlying rationale and workflow, including regular database searches, AI-assisted categorisation, and an interdisciplinary editorial and review process. It also presents descriptive data on the screened and featured literature and summarises early user feedback. We discuss the systematic limitations and potential selection biases of the format, its implications for risk communication in a changing media landscape, and howSpotlight on EMF Researchcomplements existing scientific EMF literature information services.
Escalating geopolitical instability and the persistent risk of radiological or nuclear incidents highlight an urgent need for resilient global radiation emergency preparedness. In such crises, rapid and reliable biological dose assessment is indispensable for triage, therapeutic stratification, and long-term health surveillance. While the dicentric chromosome assay remains the gold standard for biodosimetry, its labour-intensive nature, limited throughput, and variability in implementation constrain large-scale responsiveness. Emerging approaches, including DNA-DSB repair foci analysis and G0-phase premature chromosome condensation combined with fluorescencein situhybridisation, offer promising acceleration, yet lack universally harmonised validation frameworks. Despite the existence of regional and international initiatives, global biodosimetry capacity remains fragmented, with heterogeneous protocols, uneven infrastructure, and limited interconnectivity. This commentary contends that isolated excellence is insufficient in the face of potential mass-casualty scenarios that transcend national boundaries. We propose the establishment of a formally integrated global biodosimetry consortium anchored in coordinated interlaboratory comparisons, standardised protocols aligned with IAEA and ISO guidance, shared digital platforms, and sustained training programmes. Modelling suggests that coordinated activation of existing laboratories could increase triage capacity by orders of magnitude compared to isolated national responses. A globally harmonised biodosimetry framework is not merely a technical aspiration; it is a strategic imperative. Integration will enhance scientific rigour, operational scalability, and collective resilience against radiological emergencies of unprecedented scale.
Occupational dosimetrists are asked to estimate and assign effective dose for radiation workers' dose of record. An informal poll taken at a recent International Commission on Radiological Protection (ICRP) virtual workshop suggests there may be confusion or misconceptions among those practicing in the field of radiation protection as to which dose(s) should be assigned to a worker's record as described, defined, and recommended by the ICRP. Multiple ICRP publications make clear that the effective dose assigned to a worker's record should be that which the Reference Person would theoretically receive if they received the same radiation exposure as the worker. This paper briefly reviews the basis for ICRP's recommendation regarding dose of record and discusses challenges that may result with certain departures from ICRP recommendations.
Sodium chloride (NaCl) has been proposed as a retrospective and prospective dosemeter for optically stimulated luminescence (OSL) dosimetry. The potential for NaCl pellets for individualisedin situdose assessment during a radiological or nuclear emergency was enhanced by their suitability with a portable OSL reader. The current paper studies the possibility of developing a public dosimetric badge, based on NaCl pellets and commonly available low-cost materials. Copper, aluminium and polylactic acid were tested for reducing the overresponse to low x-ray energies, and the results indicated that copper is the best candidate-material for filtering purposes. Furthermore, the ratio between filtered and unfiltered samples may potentially be used to determine the mean energy of the exposure field in some circumstances. In addition, the NaCl pellets exhibit constant response for air kerma rates between 0.006 and 1.9 Gy min-1. The fading of the pellets does not present any energy dependence. Air kerma reconstruction with three stimulation modes was investigated, and the reconstructed air kerma deviated from the nominal value between 0.8 and 7.9%, which were within measurement uncertainties. The discrepancy between Monte Carlo simulations of the exposed pellets and the experimental data is possibly due to the intrinsic luminescent efficiency of the salt, which in the current study is assumed constant for the entire energy regime. Alanine, exposed together with the NaCl pellets, was studied for the intercomparison and air kerma rate experiments, and showed accurate air kerma reconstruction, with deviation from the actual doses within ∼1σ, and no significant variation with the air kerma rate. Analysis of the alanine dose estimations investigated the conventional peak-to-peak method alongside a fitting method, which did not lead to any improvements in measurement accuracy.
Occupational radiation exposure during fluoroscopy-guided dorsolumbar spine surgery was evaluated using ATOM phantoms and carbon-doped aluminium oxide () nanoDot optically stimulated luminescence (OSL) dosemeters. A controlled 50-acquisition protocol (comprising anteroposterior, oblique, and lateral projections) was used to map organ-specific doses for an operating surgeon at 50 cm from the C-arm isocentre. The expanded measurement uncertainty was 7.6% (). In the unprotected configuration, the highest equivalent doses occurred in the thoracic region, specifically the breasts (0.0430 mSv/procedure), oesophagus (0.0335 mSv/procedure), lungs (0.0230 mSv/procedure), and stomach (0.0280 mSv/procedure). Standard protective equipment (0.5 mm Pb-equivalent) reduced these organ doses by 27.3%-42.9%. However, these reduction factors characterise the complete geometric setup rather than the intrinsic attenuation of individual shielding devices. Based on International Commission on Radiological Protection Publication 103 tissue-weighting factors, the calculated effective dose was 0.152 mSv per simulated procedure. Illustrative workload extrapolations () yielded cumulative annual effective doses of 14.58 mSv yrfor 96 procedures and 36.45 mSv yrfor 240 procedures. These scenario-based projections are highly specific to the evaluated setup, table height, and acquisition parameters. The findings support the utility of local kerma-area product-normalised dose audits, rigorous individual monitoring, and the consideration of conditional Category A classification for high-volume spine surgeons where comparable exposures are verified by local clinical practice.
After nuclear power plant decommissioning, remediation is required to ensure that radiation doses from residual radioactivity in remaining buildings do not exceed 0.1 mSv yr-1, and decontamination below this legal criterion may be considered from the as low as reasonably achievable (ALARA) perspective. Accordingly, this study conducted an ALARA evaluation of remedial actions for the reuse of remaining buildings at Kori Unit 1 to determine the need for additional remediation and to identify the optimal remedial action. Evaluation factors were identified based on the ALARA Action Level methodology of NUREG-1757 and analyses of U.S. license termination plans and were redefined to reflect site-specific characteristics. Cost factors were derived for selected remedial actions, ALARA Action Levels were calculated, and the impact of the level of decontamination was analysed. The results showed that all remedial actions yielded ALARA Action Levels greater than unity, indicating that decontamination below the derived concentration guideline level is unnecessary. Shaving exhibited the lowest ALARA Action Level and was identified as the remedial action closest to satisfying the ALARA principle. These results are expected to support ALARA-based planning of remediation activities following nuclear power plant decommissioning.
The MATROSHKA-R experiment conducted onboard the International Space Station provided invaluable data on depth-dose distributions for critical human organs exposed to the low Earth orbit (LEO) radiation environment. In this study, a high-fidelity computational model of a tissue-equivalent spherical phantom and a refined geometric representation of the Zvezda module were developed using the Geant4 Monte Carlo toolkit. In contrast to previous studies that relied on simplified cylindrical crew module models, our approach successfully and simultaneously reproduced the measured dose distributions in both the surface pocket detectors and the internal container detectors of the phantom. By correlating phantom depths with anatomical organ positions, organ-specific absorbed doses and dose equivalents were estimated. Simulations revealed that galactic cosmic rays contribute over 60% of the total dose equivalent across all organs, with contribution increasing with depth and reaching up to 81% at specific internal positions. The simulated organ dose equivalents showed close agreement with empirical data, validating the spherical phantom's utility for organ-level radiation studies. This work provides a more realistic computational basis for interpreting MATROSHKA-R measurements, and establishes a validated framework for future organ-level dosimetry studies in low-Earth orbit.
Owing to the high radiation exposure associated with computed tomography (CT) examinations and the image quality degradation caused by conventional radiation shielding materials, this study evaluated the dose reduction performance and image quality maintenance potential of a newly developed lead-free composite shielding material. This material was composed of bismuth, tungsten, tungsten carbide, aluminium, and polyurethane. Phantom-based dose measurements demonstrated that the shielding material achieved dose reduction rates ranging from 17.6% to 37.6%, depending on tube voltage. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and changes in tube current-time product (mAs) under a scout-based automatic exposure control (AEC) protocol were analysed according to the presence or absence of the shielding material across regions. For the clinical evaluation, CT scans were performed on four patients. Furthermore, the images were reviewed to evaluate whether this material affected image quality. The shielding material exhibited radiation reduction levels comparable to those reported in previous studies. SNR and CNR analyses showed minor statistical variations in certain regions; however, most differences were not statistically significant, and even significant differences remained within a range that did not compromise diagnostic image quality. Under the scout-based AEC protocol, the use of the shielding material resulted in less than 1% variation in mAs values. No visually perceptible artefacts or clinically significant image quality degradation were observed. The proposed composite shielding material demonstrated the potential to mitigate some limitations of conventional shielding materials and showed preliminary clinical feasibility as an adjunctive strategy for radiation dose reduction in CT examinations.
Fecal radiobioassay is a crucial and sensitive tool for estimating internal exposure and intake of actinides following radioactive or nuclear incidents. This study developed an analytical method to determine ²³⁷ Np in feces, utilizing TEVA resin for separation and purification, followed by detection with inductively coupled plasma mass spectrometry (ICP-MS). By introducing ²⁴² Pu as a chemical homologue tracer, which shares similar chemical behavior with ²³⁷ Np in the tetravalent state, we effectively monitored the chemical recovery of the target nuclide. We systematically optimized sample pretreatment steps, such as calcination temperature and redox conditions, along with key parameters in the TEVA resin separation process, including sample acidity and elution volume, significantly enhancing the separation and purification efficiency of ²³⁷ Np. Experimental results indicated average chemical recoveries of 79% for ²³⁷ Np and 82% for ²⁴² Pu. Furthermore, multiple repeated experiments effectively verified the method's accuracy and reliability. The established analytical procedure is practical and yields stable results, providing robust technical support for accurately quantifying ²³⁷ Np in feces, with significant applications in radiation protection and public health monitoring.
Rogwe Clarke, CBE, passed away 9 April 2026 at an age of 82 years following a short illness. He is survived by his wife and a son and a daughter and their families. His distinguished career as Directif of the UK National Radioloogical Protection Board (NRPB) and Chairman of the International Commission on Radiological Protection (ICRP) is outlined.
