The objective of this study was to compare radiation doses and imaging quality using Philips AlluraClarity (Philips Healthcare, Best, The Netherlands) X-ray system and an older generation reference system. AlluraClarity is a new generation fluoroscopy system designed to reduce radiation without compromising image quality, but reports of its use in pediatric patients are limited. Dose area products (DAP, mGy cm) and DAP/kg were compared in patients catheterized using Allura Xper and AlluraClarity systems over a year of use for each. Randomly selected studies from each system were assessed for image quality. The 430 patients imaged with Clarity were larger than the 332 imaged with Xper (median BSA: 0.74 vs. 0.64 m, p = 0.06), and median total fluoroscopic times (TFT) were similar (15.8 vs. 16.1 min, p = 0.37). Median DAPs were 8661 mGy cm (IQR: 18,300 mGy cm) and 4523 mGy cm (IQR: 11,596 mGy cm) with Xper and Clarity, respectively (p < 0.001). There was a reduction in median DAP in all procedure categories. After adjustment for BSA, TFT, and procedure type, using Clarity was associated with a 57.5% (95% CI 51.5-62.8%, p < 0.001) reduction in DAP for all procedures. Reductions did not significantly differ by weight (<10 kg, 10-40 kg, ≥ 40 kg). There was an adjusted percent reduction in DAP for each procedure category ranging from 39.0% (95% CI 25.6-50.1%, p < 0.001) for cardiac biopsies with or without coronary angiography to 67.6% (95% CI 61.2-72.8%, p < 0.001) for device occlusions. Mean overall imaging quality scores (4.3 ± 0.8 with Clarity vs. 4.4 ± 0.6 with Xper, p = 0.62) and scores based on specific quality parameters were similar in the two groups. Use of AlluraClarity substantially reduced radiation doses compared to the older generation reference system without compromising imaging quality in a pediatric cardiac catheterization lab.

ObjectiveDescribe the experiences and views of medical applicants from diverse social backgrounds following the closure of schools and universities and the cancellation of public examinations in the UK due to COVID-19.DesignCross-sectional questionnaire study, part of the longitudinal UK Medical Applicant Cohort Study (UKMACS).SettingUK medical school admissions in 2020.Participants2887 participants completed an online questionnaire from 8 April to 22 April 2020. Eligible participants had registered to take the University Clinical Admissions Test in 2019 and agreed to be invited to take part, or had completed a previous UKMACS questionnaire, had been seriously considering applying to medicine in the UK for entry in 2020, and were UK residents.Main outcome measuresViews on calculated grades, views on medical school admissions and teaching in 2020 and 2021, reported experiences of education during the national lockdown.ResultsRespondents were concerned about the calculated grades that replaced A-level examinations: female and Black Asian and Minority Ethnic applicants felt teachers would find it difficult to grade and rank students accurately, and applicants from non-selective state schools and living in deprived areas had concerns about the standardisation process. Calculated grades were generally not considered fair enough to use in selection, but were considered fair enough to use in combination with other measures including interview and aptitude test scores. Respondents from non-selective state (public) schools reported less access to educational resources compared with private/selective school pupils, less online teaching in real time and less time studying during lockdown.ConclusionsThe COVID-19 pandemic has and will have significant and long-term impacts on the selection, education and performance of our medical workforce. It is important that the views and experiences of applicants from diverse backgrounds are considered in decisions affecting their future and the future of the profession.

Physics based SRP (Solar Radiation Pressure) models using ray tracing methods are powerful tools when modelling the forces on complex real world space vehicles. Currently high resolution (1 mm) ray tracing with secondary intersections is done on high performance computers at UCL (University College London). This study introduces the BVH (Bounding Volume Hierarchy) into the ray tracing approach for physics based SRP modelling and makes it possible to run high resolution analysis on personal computers. The ray tracer is both general and efficient enough to cope with the complex shape of satellites and multiple reflections (three or more, with no upper limit). In this study, the traditional ray tracing technique is introduced in the first place and then the BVH is integrated into the ray tracing. Four aspects of the ray tracer were tested for investigating the performance including runtime, accuracy, the effects of multiple reflections and the effects of pixel array resolution.Test results in runtime on GPS IIR and Galileo IOV (In Orbit Validation) satellites show that the BVH can make the force model computation 30-50 times faster. The ray tracer has an absolute accuracy of several nanonewtons by comparing the test results for spheres and planes with the analytical computations. The multiple reflection effects are investigated both in the intersection number and acceleration on GPS IIR, Galileo IOV and Sentinel-1 spacecraft. Considering the number of intersections, the 3rd reflection can capture 99.12%, 99.14%, and 91.34% of the total reflections for GPS IIR, Galileo IOV satellite bus and the Sentinel-1 spacecraft respectively. In terms of the multiple reflection effects on the acceleration, the secondary reflection effect for Galileo IOV satellite and Sentinel-1 can reach 0.2 nm/s 2 and 0.4 nm/s 2 respectively. The error percentage in the accelerations magnitude results show that the 3rd reflection should be considered in order to make it less than 0.035%. The pixel array resolution tests show that the dimensions of the components have to be considered when choosing the spacing of the pixel in order not to miss some components of the satellite in ray tracing. This paper presents the first systematic and quantitative study of the secondary and higher order intersection effects. It shows conclusively the effect is non-negligible for certain classes of misson.

ObjectivesTo compare in UK medical students the predictive validity of attained A-level grades and teacher-predicted A levels for undergraduate and postgraduate outcomes. Teacher-predicted A-level grades are a plausible proxy for the teacher-estimated grades that replaced UK examinations in 2020 as a result of the COVID-19 pandemic. The study also models the likely future consequences for UK medical schools of replacing public A-level examination grades with teacher-predicted grades.DesignLongitudinal observational study using UK Medical Education Database data.SettingUK medical education and training.ParticipantsDataset 1: 81 202 medical school applicants in 2010–2018 with predicted and attained A-level grades. Dataset 2: 22 150 18-year-old medical school applicants in 2010–2014 with predicted and attained A-level grades, of whom 12 600 had medical school assessment outcomes and 1340 had postgraduate outcomes available.Outcome measuresUndergraduate and postgraduate medical examination results in relation to attained and teacher-predicted A-level results.ResultsDataset 1: teacher-predicted grades were accurate for 48.8% of A levels, overpredicted in 44.7% of cases and underpredicted in 6.5% of cases. Dataset 2: undergraduate and postgraduate outcomes correlated significantly better with attained than with teacher-predicted A-level grades. Modelling suggests that using teacher-estimated grades instead of attained grades will mean that 2020 entrants are more likely to underattain compared with previous years, 13% more gaining the equivalent of the lowest performance decile and 16% fewer reaching the equivalent of the current top decile, with knock-on effects for postgraduate training.ConclusionsThe replacement of attained A-level examination grades with teacher-estimated grades as a result of the COVID-19 pandemic may result in 2020 medical school entrants having somewhat lower academic performance compared with previous years. Medical schools may need to consider additional teaching for entrants who are struggling or who might need extra support for missed aspects of A-level teaching.