Automation limits operator contact during routine 18F-fluorodeoxyglucose (FDG) production, but residual manual tasks and nonroutine interventions may still determine occupational exposure. This study quantified workflow-specific effective dose during in-house FDG production at a hospital-based cyclotron facility. Production records from 39 batches performed from 4 July to 23 August 2024 were reviewed. Two radiological technologists were monitored during seven routine production sessions, and five pharmacists were monitored during 10 quality-control (QC) observations. Semiconductor electronic pocket dosimeters were worn at the head, chest, and abdomen; effective dose was estimated from the three 1-cm dose equivalent readings using a nonuniform exposure formula. For technologists, average effective dose was 0.4 ± 0.1 µSv per session for cyclotron operation and synthesis, 0.2 ± 0.1 µSv for transport, 1.1 ± 0.3 µSv for cleaning, and 1.6 ± 0.3 µSv for the total routine workflow. The average pharmacist QC dose was 2.5 ± 1.2 µSv per observation. Two of 39 batches (5.1%) required a nonroutine intervention. Event-related effective doses were 32.2 µSv for manual recovery after QC vial-transfer failure and 30.7 and 31.6 µSv for two operators recovering residual FDG after incomplete transfer. These values were approximately 19-20 times the average total routine technologist dose. Routine exposure was low, whereas infrequent disruptions produced disproportionate exposure. Radiation protection should therefore combine routine monitoring with prevention, rehearsal, shielding, and time-minimized procedures for manual QC and nonroutine recovery.

Radiation fields around collimated or shielded sources exhibit strong gradients whose accurate delineation is critical for worker protection and emergency response. Mobile robots can survey such fields, but they sample sparsely and irregularly along their trajectories, and it remains unclear which reconstruction method can be trusted, and where. Using a single dominant collimated source in a two-dimensional indoor setting, this study shows that the answer depends decisively on sampling geometry, and proposes a physics-guided Gaussian process (GP) that performs reliably under trajectory-constrained sampling. A tracked robot combining light detection and ranging (LiDAR)-based simultaneous localization and mapping (SLAM) with a γ dose-rate detector surveyed a collimated Cs-137 field in seven independent runs, and all methods were evaluated under both random hold-out (interpolation near visited locations) and spatial block cross-validation (extrapolation into unvisited regions); truth-referenced evaluation against a dense reference field is provided by Poisson-sampled simulations, while experimental accuracy is cross-validated on held-out measurements. Under uniform sampling, a multilayer perceptron (MLP) robustly outperformed GP variants (R2=0.95, stable across 18 seed combinations); under trajectory sampling, its advantage vanished at visited locations and reversed catastrophically in unvisited regions. The proposed physics-guided GP, which uses a fitted collimated-beam template as the GP mean with a Matérn 3/2 residual process, achieved the highest extrapolation R2 (median 0.61; best baseline 0.31), reduced the extrapolation error by 32-69% relative to all eight baselines, recovered interpretable source parameters, and provided predictive intervals with approximately calibrated region-level coverage (point-wise error ranking remains weak); a runtime fit-quality gate further renders the correctness of the embedded prior an observable quantity, so the method flags when its own assumptions fail. These results offer quantitative guidance for method selection in robotic radiation mapping under the as low as reasonably achievable (ALARA) principle.

Objectives: The objectives of this study were to investigate whether cone-beam computed tomography (CBCT) provides additional benefit in assessing periodontal infrabony defect topography, and whether assessment accuracy differed between clinicians in periodontology with different levels of experience. Background: A comprehensive assessment of the periodontal condition usually comprises clinical periodontal examination and two-dimensional radiographic evaluation. Whilst periapical radiographs are the most frequently employed for radiographic assessment of periodontal bone loss, they have some limitations in assessing infrabony defects. As a result, CBCT has been gaining attention recently as an adjunctive periodontal diagnostic modality that can overcome these limitations. It is well established that the use of CBCT for periodontal diagnosis is not routine and should only be reserved for judicious case selection in accordance with the as low as reasonably achievable (ALARA) principle. Given these considerations, studies evaluating whether CBCT provides any additional benefit in the assessment of periodontal infrabony defects remain limited, and no formal guidelines currently exist regarding its role or implementation in postgraduate periodontal education. Methods: Forty-six participants (26 residents and 20 specialists in periodontology) from three European Federation of Periodontology (EFP)-accredited centres were invited: King's College London (KCL), United Kingdom; KU Leuven, Belgium; and The University of Hong Kong (HKU), Hong Kong SAR, China. The participants were required to complete two case-based questionnaires on infrabony defect assessment, with a two-week washout period in between. Eight complex cases were presented, once with periodontal charting and periapical radiography (Questionnaire S1), and once with CBCT images in addition to the conventional data (Questionnaire S2). For all eight cases, an HKU panel performed reference-standard intra-surgical or CBCT measurements against which the participants' answers were scored. Results: Forty participants returned the questionnaires (25 residents and 15 specialists). The response rate was, therefore, 87.0%. Participants assessed the infrabony defects more accurately in Questionnaire S2 compared with Questionnaire S1 (the mean scores [%] were 69.8 ± 11.9 and 63.5 ± 11.8 respectively); the mean difference was statistically significant (p < 0.001). When comparing residents and specialists, the mean difference in scores (%) was 0.5 (95% CI: -7.4-8.5) for Questionnaire S1 and -2.5 (95% CI: -10.4-5.5) for Questionnaire S2, with neither difference reaching statistical significance (p > 0.05). However, a larger study is required to draw more definitive conclusions about differences between clinician groups. Conclusions: CBCT, adjunctive to conventional periodontal diagnostics, provided statistically significant additional benefit in assessing infrabony defect topography by increasing assessment accuracy. However, whether the magnitude of this improvement is clinically meaningful requires further research. This study shows that between residents and specialists in periodontology, there was no statistically significant difference in the accuracy of infrabony defect topography assessment; nonetheless, given the limited sample size, further work is needed to clarify potential between-group differences. Whilst keeping the ALARA principle in mind, this study highlights the need for further investigation into the value of CBCT in complex periodontal cases, emphasises the importance of defining its role in postgraduate periodontal education, and underscores the need for a larger-scale study involving additional EFP-accredited centres to enable more robust conclusions.

The principle of optimisation of protection is a cornerstone of the system of radiological protection (RP). The practical implementation and interpretation of optimisation, particularly at low doses and dose rates, is a long-recognised challenge and has often been subject to robust and spirited debate. At present, we seem to have unprecedented interest and momentum for reflection on RP recommendations and standards, and with it the opportunity to collaboratively develop creative solutions to such challenges in support of a sustainable future. Potential solutions should be informed by science as well as a wide range of social and economic factors and be thoroughly and critically evaluated accordingly. In the United States (US), Executive Orders have led to relevant proposed rule changes from the US Nuclear Regulatory Commission (NRC), including one entitled 'Reforming and Modernizing the NRC's Radiation Protection Framework'. This paper argues that the proposal is rushed, imprecise and insufficient by highlighting a few illustrative examples of how the proposed rule change as written is inconsistent with international (e.g. International Commission on Radiological Protection) and national (e.g. US National Council on Radiation Protection and Measurements) recommendations and guidance. For example, the proposal claims that adherence to regulatory dose limits provides a sufficient level of protection and that beyond prescribed actions at certain thresholds, there is no need for further incorporation of the prevailing circumstances (i.e. no need to optimise protection) below these dose limits. National authorities of course have the purview to decide what is most appropriate and effective from a regulatory standpoint, but diverging from the broader consensus requires a clear, thoughtful, thorough and transparent argument that is missing from the current proposal.