Setup Variations Research Articles

Accelerated Low-Dose Total Skin Electron Beam Therapy Using the Modified Stanford Technique: An In Vivo Dosimetry Confirmation Study.

Purpose Low-dose total skin electron beam therapy (LD-TSEBT) has recently gained popularity in treating mycosis fungoides (MF) due to its reduced toxicity and favorable response rates. Combining accelerated LD-TSEBT with the modified Stanford technique (mST), a condensed cycling approach, offers a promising and convenient option. However, in vivo dosimetry data confirming the effectiveness of this approach is limited. We retrospectively analyzed in vivo data from patients who received accelerated LD-TSEBT using the mST for MF. Methods Patients treated with accelerated LD-TSEBT using the mST for MF were identified. Optically stimulated radiation dosimeters (OSLDs) were used to measure doses at 10 anatomical sites: vertex, larynx, right shoulder, right forearm, right hip, umbilicus, left medial thigh, right knee, left dorsal foot, and left dorsal hand. Measurements were aggregated and compared to the prescribed dose, using the European Organisation For Research And Treatment Of Cancer (EORTC) homogeneity tolerance criteria, whichaccountfor the American Association of Physicians in Medicine (AAPM) TG023 setup variability: ±20% of the prescribed dose. Patient characteristics, demographics, and disease details were also collected. Descriptive statistics were performed to evaluate clinical and dosimetric characteristics. Results Thirty-six patients were identified, and 360 OSLD measurements were recorded. The median of all OSLD measurements relative to the prescribed dose at all sites was 97.4%. The highest median delivered dose was recorded at the umbilicus (106%)and the lowest at the left dorsal hand (79%). After accounting for deviation at the left dorsal hand, 85.8% of all OSLD measurements met the homogeneity criteria at the other anatomic sites. Other patient metrics, such as height and BMI, did not impact the median delivered OSLD dose or number of anatomical sites per patient meeting the EORTC tolerance criteria. Conclusion Accelerated LD-TSEBT using the mST delivers accurate doses, with most subjects meeting the EORTC tolerance criteria. This study supports the use of OSLDs for in vivo dosimetry in patients undergoing this regimen, ensuring adequate dosing despite the truncated cycling approach.

Reproducibility and stability of voluntary deep inspiration breath hold and free breath in breast radiotherapy based on real-time 3-dimensional optical surface imaging system

BackgroundThe aim of this study was to evaluate the inter-fraction reproducibility and intra-fraction stability of breast radiotherapy using voluntary deep-inspiration breath hold (DIBH) and free breathing (FB) based on an optical surface imaging system (OSIS).MethodsSeventeen patients (510 breath-hold sessions) treated using a field-in-field (FiF) technique and twenty patients (600 breath-free sessions) treated with a volume-modulated arc therapy (VMAT) technique were included in this retrospective study. All the patients were positioned with the guidance of CBCT and OSIS, and also monitored with OSIS throughout the whole treatment session. Eight setup variations in three directions were extracted from the treatment reports of OSIS for all sessions and were subsequently manually introduced to treatment plans, resulting in a total of 296 perturbed plans. All perturbed plans were recalculated, and the dose volume histograms (DVH) for the target and organs at risk (OAR) were analyzed.ResultsThe OSIS and CBCT for both DIBH and FB treatments showed a good agreement of less than 0.30 cm in each direction. The intra-fraction respiratory motion data during DIBH were −0.06 ± 0.07 cm, 0.12 ± 0.15 cm, and 0.12 ± 0.12 cm in the lateral, longitudinal, and vertical directions, respectively; for FB, the respiratory motion data were −0.02 ± 0.12 cm, 0.08 ± 0.18 cm, and 0.14 ± 0.20 cm, respectively. For the target, DIBH plans were more sensitive to setup errors; the mean deviations in D95 for CTV were 39.78 Gy–40.17 Gy for DIBH and 38.46 Gy–40.52 Gy for FB, respectively. For the OARs, the mean deviations of V10, V20, and Dmean to the heart; V5, V20, and Dmean to the ipsilateral lung; and Dmean to the breast were lower for the FB plan compared with the DIBH plan.ConclusionBased on OSIS, our results indicate that both DIBH and FB can provide good reproducibility in the inter-fractions and stability in the intra-fractions. When the patient respiratory motion is large, the FB technology has greater possibility for the undercoverage of the target volume, while DIBH technology is more likely to result in increases in dose to OARs (the lung, heart, and contralateral breast).

Cherenkov Imaged Bio-morphological Features Verify Patient Positioning with Deformable Tissue Translocation in Breast Radiotherapy

PurposeAccurate patient positioning is crucial for precise radiotherapy dose delivery, as errors in positioning can profoundly influence treatment outcomes. This study introduces a novel application for loco-regional tissue deformation tracking via Cherenkov image analysis, during fractionated breast cancer radiotherapy. The primary objective of this research was to develop and test an algorithmic method for Cherenkov-based position accuracy quantification, particularly for loco-regional deformations which do not have an ideal method for quantification during radiotherapy. Methods and materialsBio-morphological features in the Cherenkov images such as vessels were segmented. A rigid/non-rigid combined registration technique was employed to pinpoint both inter- and intra-fractional positioning variations. The methodology was tested on an anthropomorphic chest phantom experiment via shifting treatment couch with known distances and inducing respiratory motion, to simulate inter-fraction setup uncertainties and intra-fraction motions respectively. It was then applied to a dataset of fractionated whole breast radiotherapy human imaging (n=10 patients). ResultsThe methodology provides quantified positioning variations, comprising two components: a global shift determined through rigid registration, and a two-dimensional variation map illustrating loco-regional tissue deformation quantified via non-rigid registration. Controlled phantom testing yielded an average accuracy of 0.83 mm for couch translations up to 20 mm in various directions. Analysis of clinical Cherenkov imaging data from ten breast cancer patients compared to their first imaged fraction revealed an inter-fraction setup variation of 3.7 ± 2.4 mm in the global shift and loco-regional deformation up to 3.3 ± 1.9 mm (95th percentile of all regional deformation). ConclusionsThis study introduces the use of Cherenkov visualized bio-morphological features to quantify the global and local variations in patient positioning based on rigid and non-rigid registrations. This new approach demonstrates the feasibility to provide quantitative guidance for inter-/intra-fraction positioning, particularly for the loco-regional deformations that have been unappreciated in current practice with conventional imaging techniques.

Telemedicine networks for acute stroke: An analysis of global coverage, gaps, and opportunities.

Despite the proven efficacy of telestroke in improving clinical outcomes by providing access to specialized expertise and allowing rapid expert hyperacute stroke management and decision-making, detailed operational evidence is scarce, especially for less developed or lower income regions. We aimed to map the global telestroke landscape and characterize existing networks. We employed a four-tiered approach to comprehensively identify telestroke networks, primarily involving engagement with national stroke experts, stroke societies, and international stroke authorities. A carefully designed questionnaire was then distributed to the leaders of all identified networks to assess these networks' structures, processes, and outcomes. We identified 254 telestroke networks distributed across 67 countries. High-income countries (HICs) concentrated 175 (69%) of the networks. No evidence of telestroke services was found in 58 (30%) countries. From the identified networks, 88 (34%) completed the survey, being 61 (71%) located in HICs. Network setup was highly heterogeneous, ranging from 17 (22%) networks with more than 20 affiliated hospitals, providing thousands of annual consultations using purpose-built highly specialized technology, to 11 (13%) networks with fewer than 120 consultations annually using generic videoconferencing equipment. Real-time video and image transfer was employed in 64 (75%) networks, while 62 (74%) conducting quality monitoring. Most networks established in the past 3 years were located in low- and middle-income countries (LMICs). This comprehensive global survey of telestroke networks found significant variation in network coverage, setup, and technology use. Most services are in HICs, and a few services are in LMICs, although an emerging trend of new networks in these regions marks a pivotal moment in global telestroke care. The wide variation in quality monitoring practices across networks, with many failing to report key performance metrics, underscores the urgent need for standardized, resource-appropriate, quality assurance measures that can be adapted to diverse settings.

Kinetic modelling and mechanism elucidation of catalyst-free dimethyl terephthalate hydrolysis process intensification by reactive distillation

Polyethylene terephthalate (PET) is a widely used thermoplastic polymer in the packaging and materials industries, and is predicted to have continuous market growth in the future. Methods such as glycolysis and methanolysis of PET have been identified as promising approaches in sustainable chemical recycling of PET. The latter produces dimethyl terephthalate (DMT), which can be easily hydrolyzed to terephthalic acid (TPA) at elevated temperatures and pressures, and further reused for PET production. The aim of this study was to develop a kinetic model for the hydrolysis of dimethyl terephthalate, using the experimental data. Various reaction conditions (temperature, pressure, time) have been investigated and used to calculate the activation energies and reaction rate constants, while the variation in reactor setup with methanol (MeOH) removal was conducted to show its detrimental effect on the efficiency of the reaction and selectivity towards terephthalic acid. The first reaction step of DMT to monomethyl terephthalate (MMT) is relatively irreversible, while the second reaction step of MMT to TPA ceases, as soon as the equilibrium is reached. Highest yields of TPA (76.7 %) were obtained after 40 min at 265 °C, with MeOH removal, and the activation energy was calculated to be 95 and 64 kJ mol−1 for the first and second hydrolysis reaction step, respectively.

Establishing a dedicated UTI clinic: Challenges and a guide to success

IntroductionUrinary tract infections (UTIs) have a significant impact on quality of life for patients and present complex management issues that challenge healthcare systems. Recognizing these challenges, dedicated UTI clinics are being established to provide comprehensive care. We aimed to explore the key elements, challenges, and potential solutions in setting up and running UTI clinics. By drawing insights from discussions with specialists from existing centres, we seek to provide guidance for healthcare professionals intending to establish UTI clinics de novo. MethodsWe conducted a qualitative study involving discussions with medical specialists from UTI clinics (Switzerland, UK, Netherlands). Initial insights were gathered through group discussion, followed by refinement through email correspondence. Analyses focused on identifying key themes associated with successful clinic operation, challenges encountered, and strategies employed to overcome them. ResultsKey elements identified in the running of successful UTI clinics included multidisciplinary and patient-centred approaches, as well as staff dedicated to the management of UTI. Discussions highlighted the importance of combining expertise from urology, clinical infectious diseases, nursing and microbiology to address complex UTI cases effectively. Challenges identified encompassed logistical issues in establishing multidisciplinary clinics, waiting lists, knowledge gaps, and resource allocation. Strategies to address these challenges varied depending on the context. ConclusionsDespite variations in clinic setups and patient populations, the common goal of UTI clinics is to improve patient outcomes and reduce the burden on healthcare systems. Future efforts should focus on effectiveness of different operational models to optimise complex UTI management. Building prospective patient cohorts and collaborative data analysis are crucial steps toward filling knowledge gaps and improving patient care.

Analysing Double Shearing Mechanism in Fiberglass Rock Bolting Systems: a Comprehensive Analytical Model and Numerical Simulation Approach

An analytical method and numerical simulation were developed to investigate the shear performance of fiberglass rock bolts (20-tonne and 30-tonne) by conducting sixteen double-shearing tests with both clean and infilled shear interfaces. Following the preparation of the required samples, each test set-up was subjected to different ranges of pretension values. The infilled scenario involved 5 mm thick sandy clay infilled shear interfaces. The results of the double shearing tests unveiled that as pretension increased, so did the confining pressures at the shear interfaces for both clean and infilled joints. Also, an analytical model was developed utilising the Fourier transform, energy balance theory, and linear elastic theory. The result was an empirical relationship that could determine the double shear performance of fibreglass rock bolts in close agreement with the experimental data. Coefficients were incorporated to facilitate model calibration and tuning. Eventually, fast Lagrangian analysis of continua (FLAC) three-dimensional (3D) modelling was utilised to conduct numerical simulations of fibreglass rock bolts subjected to double shearing scenarios. The numerical model was calibrated against experimental data and then extended to conduct a sensitivity analysis on fibreglass rock bolts subjected to double shear test setup variations. Scenarios included rock bolt installation angles, shearing rates, and various host rock strengths. The results revealed that increasing the shear speed from the experimental test baseline yielded substantial displacement increases in the post-failure residual performance of the rock bolts. Changing the installation angle resulted in greater peak shear forces and extended residual zones. The least significant impacts were observed when changing the host rock UCS, suggesting neither rock bolt was drastically impacted by weak or strong host rocks.

Small-scale physical modelling of vertically loaded, cyclically thermally-activated helical piles

To investigate the use of thermally-activated helical piles in shallow geothermal energy systems, a 1-g modelling study was conducted. Helical piles with either a single- or double- helix were installed in a medium dense, dry sand, and subjected to mechanical, thermal only and thermo-mechanical loading. The results indicate that during the thermal tests (1 – 3 cycles), a small upwards residual displacement was observed and pile head movements ranged between about 90% and 100% of the free expansion of the pile shaft above the shallowest helix, suggesting that the helices fixed the shaft and little restraint was offered by the surrounding soil. In the thermo-mechanical tests (30 thermal cycles), the pile head developed irrecoverable settlement as a function of the number of helices (more helices, less settlement) and initial load (higher load, greater settlement). No significant alteration in pile axial stiffness or resistance was found for piles with zero mechanical load that underwent only a few thermal cycles; however, an increase in stiffness and resistance, beyond that due to inherent variability in the test setup, was observed for piles with an initial load and following a large number of thermal cycles. The testing of thermally-activated helical piles in sand has confirmed that the response is similar to conventional piles and that thermal ratcheting effects can be managed by the application of suitable margins of safety in design and/or the use of multi-helix piles.

Effect of body contour changes on the setup and dosimetric accuracy of radiotherapy after cervical cancer surgery.

The body contour of patients with cervical cancer is prone to change between radiotherapy sessions. This study aimed to investigate the effect of body contour changes on the setup and dosimetric accuracy of radiotherapy. 15 patients with cervical cancer after surgery were randomly selected for retrospective analysis. The body contours on the once-per-week cone-beam computed tomography (CBCT) were registered to the planning CT (pCT) for subsequent evaluation. A body contour conformity index (CIbody) was defined to quantify the variation of body changes. The body volume measured by CBCT was collected, and its relative difference in reference with the first CBCT was calculated and denoted by ΔVn. The relative setup errors, denoted by ΔSELR, ΔSEAP, ΔSESI, and ΔSEvec for left-right, anterior-posterior, superior-inferior, and vectorial shifts, respectively, were defined as the difference in measured setup errors between the reference and following CBCTs. The planned dose was calculated on the basis of virtual CT generated from CBCT and pCT by altering the CT body contour to fit the body on CBCT without deformable registration. The correlations between body contour changes and relative setup errors as well as dosimetric parameters were evaluated using Spearman's correlation coefficient rs . CIbody was found to be negatively correlated with the superior-inferior and vectorial relative setup errors ΔSESI (rs = -0.448, p = 0.001) and ΔSEvec (rs = -0.387, p = 0.002), and no significant correlation was found between relative setup errors and ΔVn. Moreover, ΔVn was negatively correlated with ΔD2 (rs = -0.829, p < 0.001), ΔD98 (rs = -0.797, p < 0.001), and ΔTVPIV (rs = -0.819, p < 0.001). ΔD2, ΔD98, and ΔTVPIV were negatively correlated with ΔVn (p < 0.005). No correlation was found for other examined dosimetric parameters. The body contour change of patients could be associated with the setup variability. The effect of body contour changes on dose distribution is minimal. The extent of body change could be used as a metric for radiation therapists to estimate the setup errors.

Hoop Stress Elicited at Medial Tibial Crural Fascia Attachment During Passive Dorsiflexion: A Proof-of-Concept Study for Medial Tibial Stress Syndrome Causation.

Identification of a specific causal mechanism for medial tibial stress syndrome has been elusive, although there is a consensus that it may be caused by traction on the tibial periosteum elicited by soft tissues. The crural fascia (CF) attaches directly to the tibia throughout the length of the leg, encircling it in a grossly cylindrical fashion, and the leg may thus be viewed as a type of fluid-filled cylinder, subject to both longitudinal and hoop stresses. Prior researchers have not considered the possibility that strain on the medial tibia could be produced by the CF during gait and passive stretching, secondary to fluid pressure increases in the fascial compartments of the leg. The purpose of the present research was to verify the existence of measurable hoop strain in the CF of a cadaver donor at the medial tibial border during a heel cord stretch. Strain gauges were affixed to the CF of a cadaver donor to measure hoop and longitudinal strain during repeated heel cord stretches applied manually, and with measurements taken from each strain gauge separately. Passive heel cord stretches produced 182.96 × 10-3 mV/V and 138.00 × 10-3 mV/V hoop strain in the CF, in the distal third and middle third of the leg, respectively. A maximum longitudinal strain in the CF of the superficial posterior compartment of 75.00 × 10-3 mV/V was also produced. A heel cord stretch applied to a cadaver donor can elicit a measurable hoop strain within the CF attachment to the medial border of the tibia, in a grossly 2-to-1 manner consistent with the ratio of hoop to longitudinal strain seen with gases and liquids in a closed cylinder. Further research is indicated to replicate these results in multiple subjects, with variation in cadaver fixative and experimental set-up.

Examining the Effects of Embodiment on Working Memory Performance in VR

This study investigates the impact of immersive virtual reality (VR) environments on working memory task performance and the role of embodiment in VR. Sixteen participants engaged in N-back tasks presented either on a computer screen or in VR. Participants were assigned to one of four conditions: non-VR, VR without mimicking, VR with mimicking, or VR with mimicking and virtual mirror. Statistical analyses revealed no significant differences in sense of embodiment or task performance among the VR conditions. Additionally, there were no significant changes in working memory performance across conditions. While the findings suggest that variations in VR setups may not affect embodiment or task performance, the study’s preliminary nature emphasizes the need for larger sample sizes for more conclusive results. Further research is warranted to validate these findings and explore the effects of VR interventions on cognitive outcomes.

Optimal Correction Strategy of Image Guided Radiation Therapy Including the Paraortic Lymph Node Region in Patients With Cervical Cancers

The clinically accepted planning target volume margin for radiation therapy to the paraortic nodal region in cervical cancer patients is 5 mm. However, the comprehensive alignment and variability from the pelvic bone to all lumbar vertebrae are undetermined. This study aims to quantify the residual setup errors between the pelvic bone and lumbar vertebrae and determine the optimal correction strategy for patients with cervical cancer. Fifteen patients underwent pretreatment mega-voltage computed tomography scans (375 total fractions). Residual setup errors and required margins for each lumbar vertebra were calculated based on registrations accounting for pelvic rotation and translation. The systematic residual errors (1 SD) at L1, L2, L3, L4, and L5 using pelvic bone registration were 6.5, 4.9, 3.1, 1.5, and 0.6 mm in the anterior-posterior (AP) direction, 3.1, 2.3, 1.4, 0.6, and 0.3 mm in the right-left direction, and 2.7, 2.2, 1.7, 1.0, and 0.5 mm in the superior-inferior direction, respectively. The residual setup errors were the largest in the AP direction. Registration based on the pelvic bone required margins in the AP direction of 16.0, 12.1, 7.7, 3.6, and 1.3 mm for L1, L2, L3, L4, and L5, respectively, whereas registration based on L3 required margins of 8.8, 4.8, 4.4, 7.1, and 7.7 mm for L1, L2, L4, L5, and pelvic bone, respectively. Considerable local setup variability was found in patients with cervical cancer. After reviewing the corrective strategies, we determined that L3-based registration effectively minimized the required margins.

Forecasting PM10 Concentrations Using Artificial Neural Network in Imphal City

In this study, a forecasting system is developed for predicting PM10 levels in Imphal City over the next three days (+1, +2, and +3 days) using artificial neural networks (ANN). The experimental findings indicate that the ANN model can achieve reasonably accurate predictions of air pollutant levels. Moreover, optimizations in model performance are explored through variations in input parameters and experimental setups. Initially, predictions for each of the +1, +2, and +3 days are made independently using the same training dataset. Subsequently, cumulative predictions for +2 and +3 days are generated using previously predicted values from preceding days, yielding improved prediction accuracy. Additionally, the study identifies the optimal size of the training dataset, determining that using data spanning 3 to 15 past days yields the minimum error rates in predicting pollutant concentrations. Finally, the investigation includes the consideration of days-of-week as an input parameter, which enhances forecast accuracy noticeably.

Quality assurance and other challenges in paediatric radiotherapy: Accurate delivery of craniospinal radiotherapy.

Cranio-spinal radiotherapy (CSI) is used to treat central nervous system malignancies in paediatric, adolescent/young adult (AYA), and adult patients. Its delivery in the paediatric/AYA population is particularly challenging across different age groups. This study aims to assess the setup variations and dosimetric impact of CSI in paediatric and AYA patients. This retrospective analysis included, 10 paediatric and AYA patients (aged 4-25) who underwent volumetric modulated arc therapy (VMAT) CSI between 2016 and 2022. Patient characteristics, diagnoses, prescribed CSI doses, and fractionation details were assessed. CT simulation and treatment planning followed standard protocols with setup errors were quantified by comparing daily treatment setup images with the planned position. The study evaluated the dosimetric impact on target volumes and organs at risk (OARs). The setup errors were identified, ranging from 0.5 to 6.2 mm in different directions, especially in the cranio-caudal direction. Despite these variations, there was minimal impact observed on the coverage of clinical target volumes (CTV) and doses to OARs (<1% relative change). Ensuring precise setup in paediatric and AYA patients undergoing CSI is essential to maintain adequate CTV coverage. Although occasional substantial setup variations occurred during treatment, they had a limited impact on CTV coverage and OAR doses when infrequent. Appropriate planning target volume (PTV) margins can effectively compensate for occasional shifts. However, systematic errors could compromise treatment quality if undetected. Regular off-line review of patient set-up trends is recommended.

Major colorectal surgery with Hugo™ RAS: initial experience of a German center and a review of the literature

The recently introduced Hugo RAS robotic platform has mostly been used for well standardized urologic and gynaecologic procedures. Experience with this new system in general surgery and especially in major colorectal surgery is very limited. This is a retrospective series of the first 25 consecutive non-selected colorectal surgeries performed at a single German center. The lessons learned from our initial experience are presented along with a systematic review of the currently available literature on this topic. Ten sigmoid and seven rectal resections, four right and one left hemicolectomies, two Hartmann’s reversals and an abdominoperineal resection were performed in 14 women and 11 men at the median age of 66 years for 12 benign findings and 13 malignancies. All procedures were performed using four robotic ports and a single 12 mm assistant port. Median docking, console and total operative times were 12, 170 and 270 min. Median blood loss was < 100 ml, and median stay was 8 days. The literature review identified five case series with a total of 23 colorectal procedures: 9 right and 1 left hemicolectomies, 5 ileocaecal, and 4 rectal and 4 sigmoid resections. Results corresponded to ours despite variations in setup used by different authors. A wide spectrum of major colorectal surgery can be safely and effectively performed with the Hugo RAS, even in a cohort of non-selected patients. Ongoing software and hardware upgrade, introduction of robotic energy devices and increasing surgical experience are expected to facilitate procedures and reduce duration of surgery.

Expert consensus on clinical application of inhaled nitric oxide therapy (2024 edition)

Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator that has been used in newborns, children, and adults with various cardiopulmonary diseases to reduce pulmonary artery pressure and improve oxygenation. Currently, there are numerous brands of iNO devices on the market with significant differences in performance, as well as variations in connection and setup. Additionally, adverse reactions such as methemoglobinemia may occur during iNO treatment. Therefore, the safety and efficacy of this treatment need to be ensured in clinical practice. To address these concerns and standardize the clinical application of iNO therapy, the Respiratory Care Group of Chinese Thoracic Society and Respiratory Therapist Working Group of Respiratory Career Development Committee, Chinese Association of Chest Physician have organized relevant experts to develop an expert consensus on the clinical application of iNO therapy based on the latest research progress and clinical operational experience. This consensus includes 11 expert consensus recommendations on indications and contraindications of iNO, selection and connection of iNO devices, dose selection and therapeutic effect evaluation of iNO, adverse effects and occupational protection during iNO treatment, transport of patients with iNO, weaning of iNO, cleaning, disinfection and maintenance of iNO devices, and iNO clinical use process and records. The aim is to improve the cognitive and practical ability of clinical practitioners for the standardized application of iNO therapy, so as to ensure the safety and effectiveness of clinical application of iNO therapy.

Mass, Density, and Radius of Asteroid (16) Psyche from High-precision Astrometry

We characterize asteroid (16) Psyche using high-precision astrometry, including the recent Gaia Focused Product Release. The gravitational perturbations of Psyche on other asteroids can be observable in the case of mutual encounters. Using a least squares approach, we estimate the mass of Psyche by fitting astrometric data of asteroids that come within 0.05 au of Psyche. Combining the resulting individual estimates, we find GM = 1.601 ± 0.017 km3 s−2. This result is robust against variations in the orbit determination setup and specific data set used. The volume and equivalent radius of Psyche are currently constrained by occultations and radar and optical imaging to (5.75 ± 0.19) × 106 km3 and 111−0.5+2 km, respectively. Given the volume of Psyche, our mass estimate corresponds to a bulk density of 4172 ± 145 kg m−3, which is compatible with an M-type taxonomic classification. Finally, the phase-dependent photocenter offset is visible in the residuals of Gaia astrometric observations of Psyche. This effect is consistent with the size of Psyche.

Comparing immobilisation devices in gynaecological external beam radiotherapy: improving inter-fraction reproducibility of pelvic tilt.

The aim was to determine which immobilisation device improved inter-fraction reproducibly of pelvic tilt and required the least pre-treatment setup and planning interventions. Sixteen patients were retrospectively reviewed, eight immobilised using the BodyFIX system (BodyFIX®, Elekta, Stockholm, Sweden) and eight using the Butterfly Board (BB) (Bionix Radiation Therapy, Toledo, OH, USA). The daily pre-treatment images were reviewed to assess setup variations between each patient and groups for pelvic tilt, pubic symphysis, sacral promontory and the fifth lumbar spine (L5). Compared with the planning CT, pelvic tilt for most patients was within ±2° using the BodyFIX and ± 4° for the BB. The Butterfly Board had a slightly higher variance both for patient-to-patient (standard deviation of the systematic error) and day-to-day error (standard deviation of the random error). Variance in position between individual patients and the two stabilisation devices were minimal in the anterior-posterior (AP) and superior-inferior (SI) direction for the pubic symphysis, sacral promontory and L5 spine. Re-imaged fractions due to pelvic tilt reduced by about half when BodyFIX was used (39.1% BB, 19.4% BodyFIX). One patient treated with the BB required a re-scan for pelvic tilt. Three patients required a re-scan for body contour variations (two using BodyFIX and one with the BB). BodyFIX resulted in a more accurate inter-fraction setup and efficient treatment and is used as the standard stabilisation for gynaecological patients at our centre. It reduced the pelvic tilt variance and reduced the need for re-imaging pre-treatment by half.

The role of wave setup on extreme water levels around Australia

Estimates of extreme sea levels have mainly been derived using atmospheric and tidal forcing only, but surface gravity waves are a key process that can cause a substantial elevation of mean sea level at the coast. In this paper a coupled wave-circulation model was used to simulate storm surge and wave setup across a broad range of coastal topographies and storm types around Australia. The main aim was a practical assessment of the benefits and limitations of using a coupled wave-surge model to determine wave effects for extreme sea level studies on the continental scale. The simulations included: tropical cyclones Yasi (2011) and George (2007) on the northeast and northwest coasts of Australia; Cyclone Alby (1978) that underwent extratropical transition in southwest Australia; and a large extratropical winter storm in the Southern Ocean (2016). Predicted wave setup was highly variable both spatially and temporally, with values up to 0.45 m, 35% of maximum storm surge height, and 9% of incident significant wave heights. In general, where storm surge heights were smaller, the relative importance of wave setup increased in the presence of large waves. The model best resolved wave setup in shallow gently sloping coastal areas, whilst unrealistically low values were predicted for steep coastlines. Predictions improved when wave setup was included for most sites and events, however, these wave effects were often secondary to other assumptions implicit in modeling extreme events. This was especially true for tropical cyclones where reliable wind forcing was not available. The results showed similar contributions from wave setup to other studies but highlighted the high temporal and spatial variability of wave setup across a wider variety of storms and coastal morphologies. The results also revealed that the maximum wave setup did not always coincide with the maximum storm surge. Overall, the coupled wave-surge model presented a useful tool to predict extreme water levels including wave setup when accurate depth and atmospheric data are available, however, significant challenges still exist to model this process at the continental scale.

Sum rule comparison of narrowband and broadband sum frequency generation spectra and comparison with theory

Earlier sum frequency generation (SFG) experiments involve one infrared and one visible laser, and a measurement of the intensity of the response, yielding data on the surface sensitive properties of the sample. Recently, both the real and imaginary components of the susceptibility were measured in two different sets of experiments. In one set, a broadband infrared laser was used, permitting observations at very short times, while in another set the infrared laser was narrowband, permitting higher spectral resolution. The differences in the spectrum obtained by the two will be most evident in studying narrow absorption bands, e.g., the band due to dangling OH bonds at a water interface. The direct comparisons in the integrated amplitude (sum rule) of the imaginary part of the dangling OH bond region differ by a factor of 3. Due to variations in experimental setup and data processing, corrections were made for the quartz reference, Fresnel factors, and the incident visible laser wavelength. After the corrections, the agreement differs now by the factors of 1.1 within broadband and narrowband groups and the two groups now differ by a factor of 1.5. The 1.5 factor may arise from the extra heating of the more powerful broadband laser system on the water surface. The convolution from the narrowband SFG spectrum to the broadband SFG spectrum is also investigated and it does not affect the sum rule. Theory and narrowband experiments are compared using the sum rule and agree to a factor of 1.3 with no adjustable parameters.