Small field measurements using electronic portal imaging device.

Purpose/Objective. Small-field measurement poses challenges. Although many high-resolution detectors are commercially available, the EPID for small-field dosimetry remains underexplored. This study aimed to evaluate the performance of EPID for small-field measurements and to derive tailored correction factors for precise small-field dosimetry verification.Material/Methods. Six high-resolution radiation detectors, including W2 and W1 plastic scintillators, Edge-detector, microSilicon, microDiamond and EPID were utilized. The output factors, depth doses and profiles, were measured for various beam energies (6 MV-FF, 6 MV-FFF, 10 MV-FF, and 10 MV-FFF) and field sizes (10 × 10 cm2, 5 × 5 cm2, 4 × 4 cm2, 3 × 3 cm2, 2 × 2 cm2, 1 × 1 cm2, 0.5 × 0.5 cm2) using a Varian Truebeam linear accelerator. During measurements, acrylic plates of appropriate depth were placed on the EPID, while a 3D water tank was used with five-point detectors. EPID measured data were compared with W2 plastic scintillator and measurements from other high-resolution detectors. The analysis included percentage deviations in output factors, differences in percentage for PDD and for the profiles, FWHM, maximum difference in the flat region, penumbra, and 1D gamma were analyzed. The output factor and depth dose ratios were fitted using exponential functions and fractional polynomial fitting in STATA 16.2, with W2 scintillator as reference, and corresponding formulae were obtained. The established correction factors were validated using two Truebeam machines.Results. When comparing EPID and W2-PSD across all field-sizes and energies, the deviation for output factors ranged from 1% to 15%. Depth doses, the percentage difference beyond dmax ranged from 1% to 19%. For profiles, maximum of 4% was observed in the 100%-80% region. The correction factor formulae were validated with two independent EPIDs and closely matched within 3%.Conclusion. EPID can effectively serve as small-field dosimetry verification tool with appropriate correction factors.

Identifying emissions hotspots and strategies to reduce real-world fuel use and emissions for passenger rail: A spatially resolved approach.

The objectives of this work are to model spatially resolved passenger locomotive fuel use and emission rates, locate emissions hotspots, and identify strategies to reduce trip train fuel use and emissions. Train fuel use and emission rates, speed, acceleration, track grade, and track curvature were quantified based on over-the-rail measurements, using portable emission measurement systems, for diesel and biodiesel passenger rail service on the Amtrak-operated Piedmont route. Measurements included 66 one-way trips and 12 combinations of locomotives, consists, and fuels. A locomotive power demand (LPD) based emissions model was developed based on the physics of resistive forces opposing train motion, taking into account factors such as speed, acceleration, track grade, and curvature. The model was applied to locate spatially-resolved locomotive emissions hotspots on a passenger rail route, and also identify train speed trajectories with low trip fuel use and emissions. Results show that acceleration, grade, and drag are the major resistive forces affecting LPD. Hotspot track segments have 3 to 10 times higher emission rates than non-hotspot segments. Real-world trajectories are identified that reduce trip fuel use and emissions by 13 % to 49 % compared to the average. Strategies for reducing trip fuel use and emissions include dispatching energy-efficient and low-emitting locomotives, using a 20 % blend of biodiesel, and operating on low-LPD trajectories. Implementing these strategies will not only decrease trip fuel use and emissions but reduce the number and intensity of hotspots and, thus, lowering the potential for exposure to train-generated pollution near railroad tracks. This work provides insights on reducing railroad energy use and emissions, which would lead to a more sustainable and environmental-friendly rail transportation system.

A pre-clerkship simulation-based procedural skills curriculum: decreasing anxiety and improving confidence of procedural skill performance.

INTRODUCTION: Pre-clerkship procedural skills training is not yet a standard across Canadian medical school curricula, resulting in limited exposure to procedures upon entering clerkship. While simulated skills training has been documented in the literature to improve performance in technical ability, anxiety and confidence have yet to be investigated despite their documented impact on performance and learning. This study therefore aims to evaluate the effect of pre-clerkship procedural skills training on medical student anxiety and confidence. METHODS: A procedural skills training program was designed based on an evidence-based near-peer, flipped classroom model of education. Ninety-two second-year medical students volunteered for the study. Fifty-six were randomized to the training group, and 36 were randomized to the control group. Students in the training group attended seven procedural skills tutorials over seven months. The control group represented the average medical school student without standardized procedural training. Student anxiety and confidence were assessed at the beginning and end of the program using the State Trait Anxiety Inventory and Confidence Questionnaires. RESULTS: Students who participated in the procedural skills program demonstrated greater reductions in their state anxiety and greater improvements in confidence compared to the control group. CONCLUSION: Longitudinal procedural skills training in the simulation setting has demonstrated improvements in anxiety and confidence among pre-clerkship medical students. These added benefits to training have the potential to ease medical students' transition into clerkship, while also contributing to a safer and more effective clinical experience. Therefore, future integration of standardized pre-clerkship procedural skills training within medical school curricula should be considered.

INTRODUCTION: Les cursus de pré-externat des facultés de médecine canadiennes ne prévoient pas systématiquement de formation sur les habiletés techniques avant, si bien qu'à leur arrivée à l'externat, les étudiants ont une exposition limitée aux gestes techniques. Tandis que l'amélioration des aptitudes techniques par la simulation est bien documentée, il n'y a aucune étude sur l'effet de ces simulations sur l'anxiété et la confiance malgré leur impact avéré sur la performance et l'apprentissage. Cette étude vise donc à évaluer l'effet d'une formation sur les habiletés techniques au pré-externat sur l'anxiété et la confiance des étudiants en médecine. MÉTHODES: Une formation sur les habiletés techniques a été conçue sur la base d'un modèle d'enseignement fondé sur les données probantes, par les quasi-pairs suivant une approche de classe inversée. Quatre-vingt-douze étudiants en deuxième année de médecine ont participé à l'étude sur une base volontaire. Cinquante-six d'entre eux ont été répartis au hasard dans le groupe qui devait recevoir la formation, et 36 dans le groupe contrôle. Les étudiants du groupe qui a reçu la formation ont assisté à sept tutoriels étalés sur une période de sept mois. Le groupe témoin représentait l'étudiant en médecine moyen sans formation normalisée axée sur les habiletés techniques. L'anxiété et la confiance des étudiants ont été évaluées au début et à la fin du programme à l'aide du questionnaire State Trait Anxiety Inventory (questionnaire sur l'anxiété chronique et réactionnelle) et d'un questionnaire sur la confiance. RÉSULTATS: Chez les étudiants qui ont participé au programme de formation sur les habiletés techniques, la baisse de l'anxiété et l'amélioration de la confiance en soi ont été plus importantes que chez les étudiants du groupe contrôle. CONCLUSION: La formation longitudinale axée sur les habiletés techniques en contexte de simulation a eu des effets positifs en ce qui concerne l'anxiété et la confiance chez les étudiants en médecine au pré-externat. La formation offre l'avantage supplémentaire de faciliter la transition des étudiants en médecine vers l'externat, tout en contribuant à rendre l'expérience clinique plus sûre et plus efficace. Il serait donc intéressant pour les facultés de médecine d'intégrer dans le cursus une formation normalisée axée sur les habiletés techniques au pré-externat.

Characterizing Fuel Use and Emission Hotspots for a Diesel-Operated Passenger Rail Service.

Spatially varying diesel locomotive fuel use and emission rates (FUERs) are needed to accurately quantify local emission hotspots and their health impacts. However, existing locomotive FUER data are typically not spatially resolved or representative of real-world locomotive operation. Therefore, existing data are of limited use in quantifying the spatial variability in real-world FUERs. The objectives of this work are to quantify spatial variability in locomotive FUERs and identify factors differentiating hotspots from non-hotspots. FUERs were measured based on real-world measurements conducted for the Piedmont passenger rail service using a portable emission measurement system. FUERs were quantified based on 0.25 mile track segments on the Piedmont route. Hotspots were defined as segments in the top quintile of segment-average FUERs. On average, hotspots contributed 40-50% to trip fuel use and emissions. Hotspots were typically associated with low-to-medium speed, and high acceleration and grade. In contrast, non-hotspots were associated with high speed, and low acceleration and grade. Hotspots were typically located near populated areas and, thus, may exacerbate air pollutant exposure. The method demonstrated here can be applied to other passenger train services to assess key trends in hotspot locations and factors that explain the occurrence of hotspots.

Identifying essential procedural skills in Canadian undergraduate medical education.

INTRODUCTION: We conducted a national survey to characterize current Canadian procedural skills training in Undergraduate Medical Education (UGME). The goals were to identify the most important procedures students should know upon graduation and assess clinician-educator perceptions regarding implementation of a pre-clerkship procedural program. METHODS: We distributed the survey to physician-educators across Canada's 17 medical schools. Respondents were directed to an individualized survey that collected demographic data, physician-educator responses on essential procedural skills, as well as physician-educator opinions on the value of a pre-clerkship procedural training program. RESULTS: The response rate for this survey was 21% (42 out of 201 distributed surveys were completed). The top 10 most important procedures identified by physician-educators included IV Access, Airway Management, Local anesthesia/field block, Casting, Spontaneous Vaginal Delivery, Testing for STIs, Phlebotomy, Suturing of Lacerations, Nasogastric Tube Insertion, and Venipuncture. Physician-educators supported a pre-clerkship procedural program. CONCLUSIONS: Identifying the most crucial procedural skills is the first step in implementing a competency-based procedural skills training program for Canadian medical students. With the list of essential skills, and the support for physician-educators in developing a pre-clerkship procedural skills curriculum, hopefully there can be future development of formalized curricula.

CONTEXTE: Nous avons mené un sondage à l'échelle nationale pour caractériser les compétences procédurales canadiennes dans la formation médicale de premier cycle. L'objectif était de reconnaître les plus importantes procédures que les étudiants devaient connaître à la fin de leur formation et d'évaluer les perceptions des cliniciens éducateurs au sujet de la mise en œuvre de leur programme procédural avant les stages. MÉTHODES: Nous avons distribué le sondage à des médecins éducateurs dans les 17 écoles de médecine du Canada. Les répondants ont été dirigés vers un sondage individualisé qui recueillait les données démographiques, les réponses des médecins éducateurs sur les compétences procédurales essentielles, ainsi que les opinions des médecins éducateurs sur la valeur du programme de formation procédurale avant les stages. RÉSULTATS: Le taux de réponse à ce sondage a été de 21 % (42 des 201 sondages distribués ont été remplis). Les dix plus importantes procédures recensées par les médecins éducateurs comprenaient l'accès IV, l'assistance respiratoire, le bloc anesthésie locale/champ, le moulage de plâtre, l'accouchement spontané par voie vaginale, les tests d'ITS, la phlébotomie, la suture des lacérations, l'insertion d'une sonde nasogastrique et la ponction veineuse. Les médecins éducateurs soutenaient un programme procédural avant les stages. CONCLUSIONS: Établir les compétences procédurales les plus essentielles représente la première étape dans la mise en œuvre d'un programme de formation dans les compétences procédurales fondé sur les compétences pour les étudiants canadiens en médecine. Avec la liste de compétences essentielles et le soutien des médecins éducateurs dans le développement d'un programme de compétences procédurales avant les stages, nous espérons qu'un programme structuré sera élaboré.

Geospatial Variation of Real-World Tailpipe Emission Rates for Light-Duty Gasoline Vehicles.

Spatial variability in real-world on-road tailpipe light-duty gasoline vehicle nitrogen oxides, hydrocarbon, carbon monoxide, and carbon dioxide emission rates, the locations of emissions hotspots, and factors that explain spatial variability are quantified. A sample of 205 vehicles were measured on four predefined round-trip study routes using Portable Emission Measurement Systems. The trips on each route were divided into segments, averaging 1/4 mile in length. Segment-average emission rates were estimated based on measured 1 Hz emission rates. Emission hotspots are defined as segments with ≥90th percentile of segment-average emission rates. The hotspots have average emission rates 2-4 times greater, depending on the pollutant, than other segments. Hotspots are of heterogeneous characteristics including road attributes and vehicle activity metrics. For example, some hotspots were on arterial roads with an upstream signalized intersection and positive road grade, whereas some hotspots were on interstates with positive grade. Vehicle activity metrics, including average vehicle specific power and relative positive acceleration, help identify the hotspots. To reliably identify a fleet-average hotspot, data are needed for at least 36-130 vehicles, depending on the pollutant.

Investigating the Electronic Portal Imaging Device for Small Radiation Field Measurements.

PURPOSE: With the advent of state-of-the-art treatment technologies, the use of small fields has increased, and dosimetry in small fields is highly challenging. In this study, the potential use of Varian electronic portal imaging device (EPID) for small field measurements was explored for 6 and 15 MV photon beams. MATERIALS AND METHODS: The output factors and profiles were measured for a range of jaw-collimated square field sizes starting from 0.8 cm × 0.8 cm to 10 cm × 10 cm using EPID. For evaluation purpose, reference data were acquired using Exradin A16 microionization chamber (0.007 cc) for output factors and stereotactic field diode for profile measurements in a radiation field analyzer. RESULTS: The output factors of EPID were in agreement with the reference data for field sizes down to 2 cm × 2 cm and for 2 cm × 2 cm; the difference in output factors was +2.06% for 6 MV and +1.56% for 15 MV. For the lowest field size studied (0.8 cm × 0.8 cm), the differences were maximum; +16% for 6 MV and +23% for 15 MV photon beam. EPID profiles of both energies were closely matching with reference profiles for field sizes down to 2 cm × 2 cm; however, penumbra and measured field size of EPID profiles were slightly lower compared to its counterpart. CONCLUSIONS: EPID is a viable option for profile and output factor measurements for field sizes down to 2 cm × 2 cm in the absence of appropriate small field dosimeters.