Correction Factor Research Articles

Commissioning small fields in lung using Monte Carlo corrected film measurements.

Current commissioning of radiotherapy treatment planning systems with heterogeneous phantoms generally measures the dose delivered in solid water downstream of the lung material. The dose delivered directly in lung material is important to characterise the uncertainty of lung stereotactic body radiotherapy (SBRT) treatments, but film measurements require a correction to accurately measure dose to lung. Monte Carlo (MC) modelled corrections were applied to film measurements used for commissioning of lung SBRT. Medium dependent correction factors, kmed, were established using 6 and 10 MV simulations to account for film being calibrated in water but measuring in regions of lung material. The correction factors are dependent on energy, field size, and position. To avoid the onerous requirement of modelling each individual beam to correctly match penumbra an alternative approach is presented where the correction is applied as a function of isodose level for a nominal field size. Improvement in central axis dose agreements was seen for all field sizes, with the largest improvement of 7% observed for 6MV 1×1cm2 field. Application of position dependent corrections improved the percentage of points passing a 5%/1mm or 3%/1mm gamma assessment in all cases, whilst a uniform central axis correction did not improve the passing rate in most cases. MC simulations provide a method for correcting dose measured in lung materials allowing more accurate comparison with treatment planning system doses. In this work a generic approach to correct small field film lung measurements as a function of isodose levels is presented.

An original medical logistics robot system design for the complex environment of hospitals with dynamic obstacles

Purpose COVID-19 has aggregated the need for a non-contact medical logistic system. A non-contact robot with self-navigation ability has greatly enhanced the efficiency of the medical logistic system. This paper aims to design a new medical logistics robot system for the complex environment of hospitals with dynamic obstacles. Design/methodology/approach Targeting a medical logistics robot system for a large-scale hospital environment, this study proposed a dynamic obstacle avoidance system to reduce the robot’s delay time as well as frequent route switching. In the algorithm, this study proposed a new loop closure detection with an artificial correction factor. Moreover, this study presented enhanced 3D object detection, improving detection accuracy in hospital environments. Findings Experimental results confirm that the robot can move along its global path and reach its destination without colliding with stationary or moving obstacles. Originality/value The medical logistics robot system has safe and stable performance in real hospital scenarios. The implementation verifies that the robot has effectiveness and reliability in both hardware and software design.

A Novel LC-MS/MS Method for the Measurement of Elexacaftor, Tezacaftor and Ivacaftor in Plasma, Dried Plasma Spot (DPS) and Whole Blood in Volumetric Absorptive Microsampling (VAMS) Devices

Background: The combination of ivacaftor, tezacaftor and elexacaftor (ETI) is approved for patients with cystic fibrosis (CF) aged two years and older and at least one F508del mutation in the CFTR gene. Variability in ETI treatment response has been repeatedly reported, and its reasons are unclear and understudied. Objectives: We present a novel liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the rapid and simultaneous quantification of ETI in plasma, dried plasma spots (DPS), and whole blood volumetric absorptive microsampling (VAMS). Methods: The method utilizes a rapid extraction protocol with 200 μL methanol after the addition of deuterated internal standards. Chromatographic separation was achieved using a reversed-phase Hypersil Gold aQ column (Thermo Fisher Scientific). The method was validated according to ICH (International Council on Harmonisation) guidelines M10 for bioanalytical method validation, demonstrating linearity in the concentration range 0.020–12.000 µg/mL. It was also proved accurate and reproducible with no matrix effect. This method was applied to anonymized samples from patients undergoing ETI treatment: eight plasma and DPS and five VAMS samples were analyzed. Results: ETI concentrations measured in plasma and DPS were interchangeable, whereas ETI concentrations in VAMS were lower than in plasma, as expected for molecules with high plasma protein binding (99%). A correction factor based on the hematocrit value was used to calculate the equivalent plasma concentration from VAMS concentrations. Conclusions: This method is suitable for pharmacokinetic (PK) studies and could facilitate the centralization of samples to specialized laboratories, supporting multicenter studies.

Particle settling in a shear-thinning, viscoelastic fluid in the presence of wall effects

The settling of particles in fluids is a widespread phenomenon and commonly involves accounting for the effects of walls. Particle settling and wall effects are well understood for Newtonian fluids but the consequences of non-Newtonian fluid properties on particle settling are less well known. Here, we present the results from a set of experiments quantifying wall effects on particle settling within quiescent shear-thinning and viscoelastic (non-Newtonian) fluids for sphere-to-tube diameter ratios λ≤0.3. We find that wall effects on particle settling are reduced in non-Newtonian fluids and settling velocities are poorly predicted by conventional wall-corrected Stokes’ equations. We show that deviations in settling velocity are due to both the shear-thinning and viscoelastic properties of the fluid. Supported by our experimental dataset, we are able to show that calculating the shear-rate based on the particle diameter length-scale corresponds to an apparent viscosity that appropriately accounts for shear-thinning effects. A further correction factor for viscoelastic behaviour based on λ and the Weissenberg number, Wi, is applied, and shows good agreement with all experimentally measured velocities. Together, we provide a quantitative method to accurately predict the terminal settling velocity of particles in shear-thinning, viscoelastic fluids up to sphere-to-tube diameter ratios of 0.3.

New relationships between macroseismic intensity and local magnitude for the volcanic region of Mt. Etna (Italy)

Abstract The volcanic region of Mt. Etna (Italy) has a well-documented historical seismic activity, with records of seismic and volcanic events on the volcano dating back to late 1633. This historical data, covering a time span longer than that recorded by instrumental seismological data, is a testament to the reliability of the intensity-magnitude relations, the only means to obtain macroseismic information, the sole indicator of the energy released by earthquakes. Previous studies in the literature have proposed various methods for converting epicentral intensity into macroseismic magnitude for the Etna region. Still, these methods were based on older datasets with limited instrumental data. The updated relationship proposed in the paper significantly improves the accuracy of macroseismic magnitude estimates, aligning them more closely with local magnitudes calculated for recent earthquakes. The study uses a dataset of 58 volcano-tectonic events from 1997 to 2018, with magnitudes between 2.5 and 4.8 and intensities ranging from IV to VIII on the EMS scale. The instrumental magnitudes were obtained from the Mt. Etna seismic catalogue and the Italian seismological database, while macroseismic data were sourced from the macroseismic catalogue of Etnean earthquakes. In the volcanic area of ​​Etna, macroseismic epicenters are often located very close to the sites where the maximum intensity is observed, this is due to the strong attenuation of seismic energy and the shallowness of the epicenters. For this reason, the epicentral intensity is generally assumed to be equal to the maximum intensity. The new relationship is tailored explicitly for shallow earthquakes (H ≤ 3 km), which are the most recurrent. It includes a correction factor for depth, making it applicable to deeper events and enhancing its relevance in real-world scenarios.

Part-scale numerical simulation for laser-powder directed energy deposition: experimental calibration

Abstract To increase the environmental sustainability of products, the repair and refurbishment of damaged or obsolete components can be carried out using additive manufacturing (AM) processes. The Laser-powder directed energy deposition (LP-DED) process is an interesting candidate due to its many potential applications, particularly for the repair of metal parts. For a more thorough knowledge and understanding of the process, numerical approaches are necessary to avoid extensive and costly experimental campaigns. In this work, an original 3D thermal FEM model is proposed to predict the temperature during the LP-DED process at the macroscopic scale. The numerical simulation was based on the layer-by-layer method using an equivalent volumetric heat source and then using the superlayer method. The predicted temperature is compared with experimental temperature measurements during the deposition of stainless steel (316L) single-bead walls and multi-layer squares. The experimental results showed the influence of process parameters and deposition strategy on the temperature, which reached a maximum around 220 °C. The numerical simulation showed an overestimation of the temperature of about 120 to 200 °C compared to the experiments for all the tests carried out. A correction factor was applied to the numerical heat source which allowed to reduce the discrepancies to 50 °C. Finally, the superlayer approach led to a reduction of computational time at the expense of accuracy. Current limitations highlighted the importance of the definition of the equivalent heat source definition and boundary conditions. The chosen approach (layer-by-layer vs. superlayer) depends on the applications and the studied geometry.

The effect of current amplitude and multi-electrode stimulation on eSRT for auditory fitting in cochlear implants with pulse-width loudness coding

Objective Neurophysiologic measures like the electrically evoked Stapedius Reflex Threshold (eSRT) offer valuable insights into personalized responses to Cochlear Implant (CI) stimuli. This study evaluates the effects of stimulation current amplitude and the number of stimulating electrodes on eSRT and its correlation with the Most Comfortable Loudness level (MCL or C-level) in all-polar, pseudo-monophasic, pulse-width loudness coded stimulations. Approach The study was conducted on seventeen adult patients with Oticon Medical implants. In these implants, current amplitude remains constant while loudness is coded through pulse-width. Stimulation amplitudes were set to low (default clinical) and high values, using single or multi electrode groups of 1, 3, and 5 (G1, G3, and G5) across five cochlear regions, spanning from apical to basal. For each amplitude and group, the eSRT detection rate and correlation with MCL were analyzed regionally and overall. Results Higher eSRT detection rates were observed in the contra-lateral ear, with G3 and G5 significantly enhancing detection over G1 for both low and high amplitudes. The current amplitude facilitated eSRT invocation, particularly for G1 and patients with higher MCLs. The correlation between eSRT and MCL was relatively high (r = 0.64–0.87) across all conditions, indicating accurate MCL estimation from eSRT at both low and high amplitudes. Discussions Among all condition interactions (amplitude, side, electrodes), low-amplitude contra-lateral G5 and high-amplitude contra-lateral G3 showed optimal modes for estimating MCL from eSRT, with linear slopes near 1.0, and detection rates of 54% and 63%, respectively. High-amplitude contra-lateral G5 further increased detection to 68%, though with a slope of 0.8, requiring a correction factor. These findings provide insights into eSRT mechanisms and its application in pseudo-monophasic all-polar CI programming. Conclusion The eSRT detection rate can be improved in pulse-width modulation cochlear implants by using multi-electrode stimulation and/or increasing the stimulation amplitude beyond the default clinical value, without significantly affecting the correlation coefficient between eSRT and MCL.

Our Experience in the Correction of Acetabular Dysplasia Using the Proposed Modification of Pelvic Osteotomy

Introduction. The proper application of pelvic osteotomies for the surgical treatment of developmental dysplasia of the hip (DDH) plays a key role in correcting acetabular dysplasia and preventing secondary hip osteoarthritis. For the correct application of pelvic osteotomies, it is mandatory to understand the three-dimensional morphology of the acetabulum and accurately determine the direction of acetabular dysplasia correction. Currently, there is no described pelvic osteotomy, which can improve femoral head coverage in any direction without significant technical limitations. Objective. This study aims to evaluate the outcomes of the modified Salter pelvic osteotomy performed at the Department of Reconstructive Orthopedics and Traumatology for Children and Adolescents at the SI “Institute of Traumatology and Orthopedics of NAMS of Ukraine.” Materials and Methods. 21 patients with DDH aged 2-6 years were selected for the retrospective study; 3-D acetabular morphology was assessed with further application of the proposed modified Salter osteotomy for correcting acetabular dysplasia. Results. A methodology for assessing the 3-D morphology of the acetabulum and determining the correction vectors for acetabular dysplasia was developed and implemented; the mid-term postoperative results after applying the proposed modification of Salter pelvic osteotomy were evaluated. The modification demonstrated significant improvement in acetabular parameters: preoperative acetabular index (AI) was 46.8 ± 12°, postoperative AI was 24.3 ± 5.1°, with a mean correction of 23.1 ± 4.9°. Further positive dynamics were observed: AI at 6 months postoperatively was 19.8 ± 4.7°, and at the final follow-up examination, it reached 15.6 ± 4.4°, while Wiberg’s angle improved to 23.3 ± 3.9°. Excellent and good clinical outcomes were observed in 57.2% and 33.3% of cases, respectively, with radiological outcomes showing excellent and good results in 66.7% and 23.8% of cases. A relatively high rate of femoral head avascular necrosis (AVN) (33.3%) correlated with a high percentage of patients with complete hip dislocation (61.9%). However, most patients with AVN (23.8%) subsequently experienced near-complete or complete restoration of femoral head structure and shape. Conclusions. 3-D acetabular morphology assessment is a key factor for the successful surgical correction of residual acetabular dysplasia in DDH cases. The proposed modification of the Salter pelvic osteotomy provides excellent and good mid-term clinical and radiological outcomes in most cases.

Development and Validation of a Time-Varying Correction Factor for QT Interval Assessment in Drug-Resistant Tuberculosis Patients.

Tachycardia associated with active tuberculosis (TB) often diminishes when patients recover from TB. Elevated heart rate (HR) may lead to sub-optimal correction, complicating the assessment of QT prolongation when using standard correction factors (CFs), such as Fridericia's formula (QTcF). Olliaro has proposed a CF for QT interval correction in pre-treatment TB patients. However, the QT-HR correlation changes as HR decreases during treatment, indicating the need for time-varying correction. We developed an HR model to capture the HR normalisation during successful treatment. Subsequently, a time-varying CF was constructed using the estimated HR change rate. The performance of CFs to make corrected QT (QTc) independent from HR was evaluated by linear regression analyses of QTc versus HR within defined time bins. The final HR model included asymptotic change in HR attributed to time on treatment, circadian rhythm cycles, M2 (bedaquiline-metabolite) concentration, and patient covariates. The time-varying CF decreased from 0.4081 to 0.33, with a half-life of 7.74 weeks. The slope (QTc/HR vs. Time) derived from the time-varying correction was not significantly different from 0 (95%CI -0.003 to 0.002), and the intercept was not significantly different from 0 (95%CI -0.089 to 0.006), demonstrating successful QT correction from pre-treatment to the end of treatment. The time-varying CF effectively captures the dynamic QT-HR relationship during TB treatment, reducing the risk of misdiagnosing QT prolongation or unnecessary discontinuation of treatment. By addressing underestimation and overestimation issues in QT interval assessment, this method enhances drug evaluation in clinical trials and supports improved treatment decisions for TB patients.

A gamma-ray imaging method for multiple radionuclides and low-activity radioactive sources.

Gamma-ray coded-aperture imaging technology has important applications in the fields of nuclear security, isolated source detection, and the decommissioning of nuclear facilities. However, artifacts can reduce the quality of reconstructed images and affect the identification of the intensity and location of radioactive sources. In this paper, a gamma-ray coded-aperture imaging method based on primitive and reversed coded functions (PRCF) was proposed to reduce imaging artifacts. Building on this, the PRCF method was improved by integrating energy spectral information collected by the detector. By selecting energy intervals corresponding to characteristic energies of different radioactive sources for data filtering, the imaging capability of the PRCF method was further enhanced for multiple radioactive sources. Through simulation, the selection range of the correction factor in the PRCF method was determined. Single-source and multi-source imaging experiments were conducted using the self-built coded-aperture imaging system based on a CdZnTe pixel detector, and the selection criteria for the energy interval ranges of different radioactive sources were established. Compared with the conventional maximum likelihood expectation maximization (MLEM) method, the improved PRCF method not only effectively reduced artifacts and enhanced the imaging quality, but also ensured the accuracy of imaging results for multiple radioactive sources. Moreover, through imaging experiments using low-activity 137Cs and high-activity 241Am and 133Ba, it was demonstrated that the PRCF method can achieve low-count imaging in complex environments, providing a solution for imaging low-activity radioactive sources.

Intensity corrections for grazing-incidence X-ray diffraction of thin films using static area detectors.

Grazing-incidence X-ray diffraction (GIXD) is the technique of choice for obtaining crystallographic information from thin films. An essential step in the evaluation of GIXD data is the extraction of peak intensities, as they are directly linked to the positions of individual atoms within the crystal unit cell. In order to obtain reliable intensities independent of the experimental setup, a variety of correction factors need to be applied to measured GIXD raw data. These include the polarization of the incident beam, solid-angle variations, absorption effects, the transmission coefficient and the Lorentz correction. The aim of this work is to provide a systematic compilation of these intensity corrections required for state-of-the-art GIXD setups with static area detectors. In a first step, analytical formulae are derived on the basis of theoretical considerations. The obtained intensity corrections are then applied to measured GIXD raw data from samples with different textures, including a single crystal and thin films containing either randomly distributed or oriented crystallites. By taking advantage of the symmetries inherent in the different types of textures, integrated peak intensities are determined, and these are compared with intensities calculated from single-crystal diffraction data from the literature. Accurate intensity corrections promise an improved quality of crystal structure solution from thin films and contribute to achieving accurate phase and texture quantifications from GIXD measurements.

Real time monitoring of Rn-222 in workplaces and estimation of working time correction factor

The potential of electronic monitors for evaluating radon exposure is still not fully harnessed, and tests under real conditions are scarce. Ten workplaces were continuously monitored for a year with the radon measurement network of Sofia University, with calibrated and metrologically assured RadonEye +2 monitors. In 7 of the workplaces the average activity concentration of radon during the working time was significantly lower than the total time average. This difference is attributed to behavioral patterns. The ratio of the working time and the total time average (called working time correction factor kWT) for the whole year ranged from 0.71 to 0.98. Its weekly values varied significantly with coefficients of variation between 9 and 28%. Therefore, using short term estimates of kWT to correct the total time radon average determined by passive detectors could lead to bias.The workplaces also exhibited different seasonal radon patterns, although most were offices with similar schedules. In most pairs of workplaces the monthly averages were correlated very weakly or even negatively. This indicates that seasonal radon variations could be specific to each workplace. The value of kWT also varied with the season, suggesting that seasonal variations of radon during working hours might differ from those observed with passive integrating detectors.Overall, long-term follow-up by metrologically assured electronic monitors could help to improve and personalize the estimate of radon exposure of workers. These monitors could potentially support smart anti-radon systems with optimal operation schedules, thereby contributing to the reduction of the energy impact of buildings.

A theoretical study on the mechanism and rate constants of luteolin and selenium dioxide.

This study investigates the reaction mechanism of luteolin with selenium dioxide in ethanol. Through a detailed search for transition states and thermodynamic energy calculations, it was found that the reaction proceeds via two possible pathways, leading to the formation of products P1 and P2, respectively. A common feature of both pathways is that the first elementary step results in the formation of the intermediate INT1. Kinetic calculations indicate that, within the temperature range of 273 to 340K, the apparent rate constant (k2) for the formation of intermediate INT1 is significantly larger than those of k3 and k4, and all three rate constants increase substantially with temperature. Interestingly, the product P1 from the first pathway is thermodynamically and kinetically feasible, and is in complete agreement with experimental results. In contrast, the product P2 from the second pathway contains a Se-O-Se ether bond, which exhibits dynamic stability in its molecular structure. In conclusion, this study not only validates the experimental findings but also provides theoretical guidance for the synthesis of novel organoselenium compounds. All calculations were performed using the DFT/M06-2X/6-31G(d,p) method. The solvent effect was considered by applying the IEFPCM model in all calculations. The free energy (∆G) of each compound at 298.15K was obtained with a correction factor of 0.967. The apparent rate constants for each step were calculated over a temperature range from 273.15 to 373.15K using transition state theory.

Buckling analysis of orthotropic plates with various boundary conditions using a new hyperbolic shear displacement model: an analytical approach

PurposeThis paper introduces a closed-form solution for analyzing the buckling behavior of orthotropic plates using a refined plate theory with four variable parameters, leveraging a new hyperbolic shear displacement model.Design/methodology/approachThe proposed theory incorporates a quadratic variation of transverse shear strains across the plate’s thickness and satisfies zero traction boundary conditions on both the upper and lower surfaces without employing shear correction factors. The governing equations are derived from the principle of minimum total potential energy. Closed-form solutions for rectangular plates, with two opposite edges simply supported and the remaining two edges subjected to arbitrary boundary conditions, are obtained using the state space approach to the Levy-type solution. Comparative studies are conducted to validate the accuracy of the obtained results.FindingsThe paper successfully examines and discusses in detail the effects of boundary conditions, loading conditions, variations in modulus ratio and thickness ratio on the critical buckling load of orthotropic plates.Originality/valueThis study presents a novel and precise method for evaluating the buckling behavior of orthotropic plates. The refined plate theory, without the need for shear correction factors, offers significant insights and improvements in understanding the critical buckling load under various conditions, contributing valuable knowledge to the field of structural analysis.

A prospective study on the correlation of right atrial pressure determined non-invasively via inferior vena cava versus tricuspid E/e among patients undergoing dobutamine stress echocardiography

Abstract Background Right atrial pressure (RAP) gives insight to a patient's cardiovascular hemodynamics and pulmonary status. It is used to estimate the pulmonary arterial pressure (PAP), but since its definite measurement requires right heart catherization, physicians tend to rely on non-invasive modalities such as echocardiography. Aside from the IVC method, secondary indices, such as tricuspid E/e' and hepatic vein flow pattern, may also be employed to estimate RAP. Methodology: This was a prospective observational single-center study done from November 2023 until April 2024 which included a total of 55 adult patients who underwent dobutamine stress echocardiography (DSE). Baseline characteristics and echocardiographic parameters were obtained, and RAP values using IVC (RAP IVC) and tricuspid E/e’ (RAP E/e’) methods were compared. The correlations of the derived systolic and mean PAP values using the two methods were also determined. Results The RAP IVC and RAP E/e’ values had statistically significant difference. The cut-off values used for tricuspid E/e’ overestimate RAP when compared with the IVC method. Analysis on sPAP values had mixed results as to the detection of pulmonary hypertension (PH). Grading of PH severity using derived mPAP values from the two methods also showed statistically significant difference. Lastly, our post-hoc analysis manifested that increasing dobutamine dose has a statistically significant effect to RAP determined via echocardiography. Conclusion At the time of this writing, estimating RAP using the tricuspid E/e’ method is not a good alternative to the IVC method. In addition, derived sPAP and mPAP values using tricuspid E/e’ also did not correlate with those determined using the IVC method. Higher tricuspid E/e’ cut-off values, larger sample size, and possible need for correction factors in the derivation of sPAP and mPAP may lead to better correlation between the two methods. Finally, our post-hoc analysis showed that dobutamine >10 mcg/kg/min can cause IVC dilatation and/or plethora, hence caution is needed when interpreting presence of IVC dilatation and/or plethora, and RAP and PAP estimates which were obtained using echocardiography among patients on dobutamine support. Demographic and clinical profile Algorithm of procedures

Correction factors for prey size estimation from PenguCams.

The use of animal-borne cameras enables scientists to observe behaviours and interactions that have until now, gone unseen or rarely documented. Researchers can now analyse prey preferences and predator-prey interactions with a new level of detail. New technology allows researchers to analyse prey features before they are captured, adding a new dimension to existing prey analysis techniques, which have primarily relied on examining partially or fully digested prey through stomach flushing. To determine prey size, the video footage captured needs a correction factor (pixel:mm ratio) that allows researchers to measure prey dimensions using image measuring software and convert the pixels to actual measurements. This in turn will help estimating the prey energy content. This method requires a reference object with known dimensions (such as beak measurements) to ground truth your distance. Using PenguCams we determined the correction factor by measuring a 2 cm section of 1 mm grid paper from video footage taken at known distances (10, 20, 30, 40, 50, 60 cm) in different salinities ranging from air and fresh water, up to 35 psu in 5 psu increments while controlling for temperature and pressure. We found no significant difference between correction factors of water at different salinities. However, due to their considerable differences in refraction index, correction factors contrast between water and air. Linear equations modelled from correction factors at tested distances help predict correction factors between tested distances and, therefore, enable a wider application of this research. We provide examples from PenguCam footage taken of Humboldt (Spheniscus humboldti), Tawaki (Eudyptes pachyrhynchus) and King (Aptenodytes patagonicus) penguins to illustrate the use of identified correction factors. This study provides a tool for researchers to further enhance their understanding of predator-prey interactions.

Assessment of a New CT Detector and Filtration Technology: Part 1 - X-ray Beam Characterization and Radiation Dosimetry.

This study evaluated beam quality and radiation dosimetry of a CT scanner equipped with a novel detector and filtration technology called PureVision Optics (PVO). PVO features miniaturized electronics, a detector cut with microblade technology, and increased filtration in order to increase x-ray detection and reduce image noise. We assessed the performance of two similar 320-detector CT scanners: one equipped with PVO and one without. Beam quality was measured by determining the half-value layer (HVL) and effective energy (Eeff) for both scanners using all tube voltages (80 kV, 100 kV, 120 kV, 135 kV) and bowtie filters (small, medium, large) available. Energy correction factors were identified for optically stimulated luminescent dosimeters (OSLDS) compared to a calibrated ionization chamber. Surface and internal doses were measured for an anthropomorphic CT angiography head phantom and a cadaver head scanned with CTDIvol matched as close as possible at the conventional (55.1 mGy) and PVO (55.4 mGy) CT scanners. For all scan settings, the PVO scanner showed significantly higher HVL (range, 4.33-11.02 mm Al) and effective energy (range, 39.4-68.0 keV) values compared to the conventional scanner (HVL, 4.19-8.25 mm Al; effective energy, 38.4-55.2 keV). For equivalent CTDIvol values, the energy-corrected surface skin and lens doses were on average 6.7% lower with the PVO scanner than the conventional scanner (P < 0.01). PVO technology yielded higher HVL and effective energies and, for the same CTDIvol, resulted in lower surface organ doses, indicating a potential for reduced patient radiation exposure in clinical settings.

Testing Methods for Masonry Cores: A way forward to increase reliability of mechanical properties evaluation

The assessment of unreinforced brick masonry structures and infrastructure is a worldwide challenge for the development of resilient urban areas and preservation of historical assets. Among other factors, the estimation of mechanical performance of masonry in existing construction is of importance. However, the characterisation effort does not always satisfy the requirements from structural analyses point of view, i.e. need of elastic, strength and toughness properties, and/or from technical point of view, i.e. use of conventional technical expertise and limited invasiveness. In this respect, the new RILEM Technical Committee CTM aims at promoting the use of tests on masonry cores for the evaluation of compression and shear properties of unreinforced masonry with regular units. Upon a state-of-the-art review, a database of previous experimental test series will be created to identify influencing factors (e.g., core’s geometry, boundary conditions). Selected testing procedures will be compared at various international institutes for a variety of masonry types typically used in existing structures and infrastructure. By comparing results with standardise tests, correction factors will be identified. Eventually, testing guidelines to characterise masonry with core specimens will be defined and shared within the research and engineering community.

Attix free-air chamber correction factors computed using EGSnrc.

A cylindrical free-air chamber, the Attix FAC, is used for absolute air-kerma measurements of low-energy photon beams at the University of Wisconsin Medical Radiation Research Center. Correction factors for air-kerma measurements of specific beams were determined in the 1990s. In order to measure air-kerma rates of beams in development, new correction factors must be computed. We aimed to compute monoenergetic correction factors for air-kerma measurements with the Attix FAC that could be used to determine corrections for arbitrary polyenergetic beams. A model of the Attix FAC was created in the Monte Carlo code, EGSnrc. The EGSnrc user codes, egs_fac, and egs_chamber, were utilized to calculate aperture transmission, scatter, collecting rod electron loss, and wall electron loss correction factors for incident monoenergetic photon beams with energies between 5 and 50keV. Beam-specific correction factors were then derived from the monoenergetic correction factors and compared with the currently accepted values. Correction factors were computed in 0.5keV intervals. The newly calculated beam-specific correction factors and the old conventional values agreed within 0.1% for all beams investigated. The process for determining monoenergetic correction factors for air-kerma measurements with a free-air chamber is detailed in this work. Beam-specific correction factors can then be calculated if photon spectra are known. This process can be carried out for any free-air chamber, given specific materials and dimensions for modeling.

Ethanol and the Limitations of the Osmol Gap.

The osmol gap can help detect and manage those with toxic alcohol exposure, and it is altered by all alcohols including ethanol. The optimal correction for ethanol that would allow accurate detection of an alternative alcohol is unclear. We conducted a prospective cohort study to assess baseline variations in osmol gap, and then to assess the validity of 2 commonly used coefficients (correction factors) for ethanol. Twenty-two healthy volunteers received a body mass-based dose of oral ethanol that targeted an estimated peak blood ethanol concentration >200 mg/dL. We measured laboratory values prior to ethanol administration and at 2, 4, and 6 hours after ingestion. We considered an osmol gap >10 or <-10 abnormal and an osmol gap of >10 after correction as a false positive. Four of the 22 subjects (18%) had an osmol gap >10 at baseline. Following ethanol ingestion and across 66 timepoints (N=66), there were 14 abnormal osmol gap tests (21%) when corrected with an ethanol coefficient of 4.6, and 31 (47%) abnormal tests when corrected using the Purssell ethanol coefficient of 3.7. The mean difference between the baseline and the post-ethanol corrected osmol gap was lower with the molecular weight correction factor of 4.6 compared with the Purssell correction factor of 3.7 (0.2 versus 11.0; P<.001). Our data show that the osmol gap is occasionally elevated absent ingestion of any alcohol, and using an ethanol correction coefficient of 4.6 produced a better clinical osmol gap input albeit still with some variation.