Varian Medical Systems (Switzerland)

Objective.The generalized equivalent uniform dose (gEUD) is a well-established metric for radiotherapy dose optimization, particularly for normal tissues. However, the lack of theoretical clarity in its application has often led to empirical use in clinical practice. This study aims to reformulate gEUD-based optimization in a theoretical framework using the gEUD curve concept, and to develop a robust optimization strategy tailored for stereotactic radiation therapy (SRT), with a specific focus on bone and spinal metastases.Approach.We interpreted the gEUD as a smooth function of itsa-parameter, forming a continuous curve whose deformability decreases with increasinga. Based on this understanding, we proposed two methods: the multiple gEUD objective (MgEUDO) for optimizing the remaining volume at risk, and the selective gEUD objective (SgEUDO) for critical organs at risk. These methods were retrospectively evaluated in 22 patients who received five-fraction SRT (35 Gy total prescription).Main results.Using consistent gEUD-based optimization, all cases achieved clinically favorable dose distributions. Compared to conventional normal tissue objective constraints, the proposed strategy reduced mean dose to surrounding tissues by 10%, while improving tumor dose coverage by 0.6%. SgEUDO further achieved 39% and 37.5% mean dose reductions in the left and right kidneys, respectively.Significance.Our theoretical and practical refinement of gEUD optimization enables systematic control of dose distribution with reduced inter-planner variability. The combined MgEUDO and SgEUDO strategies provide a generalizable and clinically effective framework for high-precision radiotherapy.

Az Első Dunagőzhajózási Társaság (a továbbiakban: DGT) által a Mohács-Pécsi Vasút (a továbbiakban: MPV) mellékvágányaiként, a történelmi Magyarország első iparvasút-hálózataként megépült Pécsi Bányavasutak 1854–1944 közötti gazdasági szerepének bemutatása. A szakirodalmakban és a dokumentumfilmek többségében a vonalak szinte csak említésként jelennek meg, holott azok nélkülözhetetlen szerepet töltöttek be a pécsi bányavidék működtetésében a szénszállítmányok célba juttatásával.

Online adaptive radiation therapy (ART) offers a paradigm shift in radiotherapy by enabling adjustments to the planned dose based on daily anatomical variation. In the context of cone-beam computed tomography (CBCT) for online ART on a standard linac, thoracic and abdominal treatment sites in particular present unique challenges due to the typically large treatment volumes, mobile anatomy, scatter-induced image quality degradation, and hounsfield unit (HU) limitations. A recent hardware and software upgrade for a standard linac, Varian TrueBeam (TB) v4.1 HyperSight, seeks to overcome these challenges through implementation of a larger kV imager panel (i.e., 43×43 cm), increased gantry speed (i.e., from 6 to 9°/s), and improved HU accuracy. However, investigation of the new upgrade is essential to harness the full potential of these advancements. We report on physical characterization and a digital Monte Carlo (MC) model of the new imaging system hardware. The open-source GEANT4 Application for Tomographic Emission (GATE) MC toolkit, which allows scintillation systems, including CBCT, to be accurately modeled, was utilized. All physical components of the new TB upgrade were modeled from vendor-provided geometry and material specifications. The model was validated using physical measurements acquired on the upgraded system. Specifically, the modulation transfer function (MTF), noise power spectrum (NPS), profiles across the physically larger detector, scatter-to-primary ratio (SPR), and loss in spatial resolution as a function of the increased gantry speed and an object's distance from isocenter. The latter was quantified using the pixel distance between the 15% and 85% intensities of the over-sampled edge spread function (ESF) for source-to-edge-phantom distances (SEPDs) of 80, 100, and 120 cm. Focal spot motion was also characterized by the MTF at SEPD of 100 cm. The MTF50 was 0.901 and 0.889 mm-1 for the measurement and simulation, respectively, for a 125 kVp beam. The normalized root mean square error (nRMSE) was 0.013. While small, the model displayed degraded spatial resolution accuracy for other beam qualities. The general trend of the physically measured normalized noise power spectrum (nNPS) curves was reproduced with the model at all beam energies; however, a small systematic offset was observed. Excellent agreement was observed between central-image x- and y-profiles of measured and MC-generated projections, indicating correct modeling of the larger imaging detector. Simulated SPRs closely agreed with those of measurement. The measured ESF widths for the 6 and 9°/s acquisitions were both 2.5 pixels, indicating no reduction in spatial resolution in the projection space as a result of the increased acquisition speed. The effect of focal spot blurring due to increased gantry speed was accurately modeled, considering ESF width differences no larger than 0.5 pixels were observed for all SEPDs. Decreased spatial resolution in projection images was observed for SEPDs of 80 and 120 cm compared to 100 cm. The MC model of the novel TB 4.1 HyperSight upgrade accurately reproduced physical measurements acquired on the new system. The model will be used alongside physical testing on the new TB platform, working towards an online CBCT-based ART protocol for thoracic and abdominal treatments.

Abstract The Faroe Islands are home to descendants of a North Atlantic founder population with a unique history shaped by both migration and periods of relative isolation. Here, we investigate the genetic diversity, population structure, and demographic history of the islands by analyzing whole genome sequencing data from 40 participants in the Faroe Genome Project. This represents the first whole genome sequencing panel of this size from the Faroe Islands. We observed numerous putatively functional private alleles, including stop gain variants and high impact missense variants in the cohort. Faroese individuals had a higher proportion of their genomes contained in long runs of homozygosity than other European groups, including Finnish, suggesting a more recent or stronger bottleneck in the Faroese population. Signals of positive selection were identified at loci containing genes that play roles in vitamin D and dietary fat absorption and DNA repair, while increased diversity on lactase persistence haplotypes was observed. Fine-scale analysis of haplotype structure in modern and ancient European genomes revealed genetic affinities with ancient Iron Age individuals from the North and West of Europe, providing evidence for potential contributions to the Faroese gene pool from Celtic and Viking populations as well as information about the temporal order in which these events happened. This study highlights the impact of evolutionary processes, such as ancient admixture, founder events, and positive selection, on the present-day genetic architecture of North Atlantic founder populations like the Faroe Islands.

BackgroundDual‐energy cone‐beam CT (DE‐CBCT) has become subject of recent interest due to the ability to produce virtual monoenergetic images (VMIs) with improved soft‐tissue contrast and reduced nonuniformity artifacts. However, efficient production and optimization of VMIs remains an under‐explored part of DE‐CBCT's application.PurposeThis work reports on the creation of DISC (dual‐energy image synthesizer for CBCT), a newly developed, open‐source user interface to efficiently produce and optimize VMIs with the eventual goal of clinical application.MethodsTwo sets of CBCT scans of a Catphan 604 phantom were acquired sequentially (80 and 140 kVp) using the on‐board imager of a commercial linear accelerator. Material decomposition into aluminum (Al) and polymethyl‐methylacrylate (PMMA) basis materials in the projection‐domain and reconstruction with the Feldkamp–Davis–Kress (FDK) algorithm of basis material images were performed in the open‐source Tomographic Iterative GPU‐based REconstruction (TIGRE) Matlab toolkit. Using DISC, a series of VMIs were generated via linear combinations of the basis material images without reconstructing individual VMIs at different energies. Hounsfield units (HU) were computed using an energy‐dependent fit over the range of 20–150 keV. VMI energies that maximized contrast‐to‐noise ratio (CNR) for various materials and minimized nonuniformity artifacts were determined with 1 keV precision.ResultsOptimal CNR values for all material inserts ranged from 55 to 62 keV, showing an average CNR enhancement of 25% over the polychromatic images. Optimal uniformity is observed at 65 keV. Computed HUs show good agreement with theoretical values, with root‐mean‐squared error of 16 HU across the range of energies and materials.ConclusionA spectrum of VMIs from DE‐CBCT was efficiently produced with 1 keV precision using DISC. Optimal energies for both soft tissue contrast and nonuniformity reduction were quickly computed with high precision. Future work will expand DISC to generate other DE‐derived image types and will explore the acquisition and optimization of DE patient images.

In online-adaptive proton therapy planning based on cone beam computed tomography (CBCT), CT number errors can pose challenges. We propose an approach for coping with CT number uncertainties by increasing range robustness settings (RRS) in online-adaptive planning. This was compared to our trigger-based offline (TB-Offline) adaptive approach, and to daily replanning using in-room CT-on-rails (CTOR). For 23 head-and-neck cancer patients, a CTOR and CBCT were acquired in a single fraction. CTOR contours were copied rigidly onto the CBCT. CBCT-based plans were generated with 3, 6, 8, 10, and 12% RRS, each with 1mm setup-RS, followed by a forward dose calculation on the reference CTOR. This was compared to dose distributions from our TB-Offline approach (3mm/3% SRS/RRS), also recomputed on the CTOR. Coverage (voxelwise-minimum) of the primary clinical target volume (CTV7000) and elective lymph nodes (CTV5425) and grade≥II normal tissue complication probabilities were compared between strategies. When going from RRS=3% to RRS=10%, the population 90th percentiles of CTV5425 V94% improved from 89.6% to 96.4%, and CTV7000 V94% from 92.8% to 96.4%. Substantial coverage loss (V94%<95%) with CBCT-based online adaptive and RRS=10% was observed in 1/23 evaluated patients for CTV7000 and 2/23 for CTV5425. This was an improvement compared to 3/23 and 4/23 with TB-Offline. Moreover, for RRS=10% the average risk of xerostomia improved by 2.4 percentage point compared to TB-Offline. Robust optimization with increased range robustness settings effectively mitigated dose degradation from CT number errors in CBCT-based online-adaptive proton therapy.

Emotional competence is what results and enhances our personal, relational and professional performance, andwhat ultimately helps us attain an overall increase in our quality of life Emotional competencies determine howwe manage ourselves. An emotional competence (EC) is a learned capability based on emotional intelligencethat results in outstanding performance at work. This study was conducted to assess the emotional competenceamong school teachers of selected schools at Trivandrum. The objectives of the study were to assess the emotionalcompetence among school teachers, and find out the association between emotional competence andselected demographic variables among school teachers. Quantitative descriptive design was adopted for thestudy and hundred teachers were selected by convenient sampling technique. Data collection tool was structuredquestionnaire to collect the socio demographic variables and PEC scale to assess emotional competenceamong school teachers. The data was analysed by using descriptive and inferential statistics. The study revealedthat 87% school teachers have average emotional competence, 10% had good emotional competence and 3%had poor emotional competence The chi-square value showed that there was a significant association foundbetween emotional competence and years of teaching experience of the teacher’s(p&lt;0.05).