Background and PurposeMagnetic Resonance (MR)-only radiotherapy enables the use of MR without the uncertainty of MR–Computed Tomography (CT) registration. This requires a synthetic CT (sCT) for dose calculations, which can be facilitated by a novel Zero Echo Time (ZTE) sequence where bones are visible and images are acquired in 65 seconds. This study evaluated the dose calculation accuracy for pelvic sites of a ZTE-based Deep Learning sCT algorithm developed by GE Healthcare.Materials and MethodsZTE and CT images were acquired in 56 pelvic radiotherapy patients in the radiotherapy position. A 2D U-net convolutional neural network was trained using pairs of deformably registered CT and ZTE images from 36 patients. In the remaining 20 patients the dosimetric accuracy of the sCT was assessed using cylindrical dummy Planning Target Volumes (PTVs) positioned at four different central axial locations, as well as the clinical treatment plans (for prostate (n = 10), rectum (n = 4) and anus (n = 6) cancers). The sCT was rigidly and deformably registered, the plan recalculated and the doses compared using mean differences and gamma analysis.ResultsMean dose differences to the PTV D98% were ≤ 0.5% for all dummy PTVs and clinical plans (rigid registration). Mean gamma pass rates at 1%/1 mm were 98.0 ± 0.4% (rigid) and 100.0 ± 0.0% (deformable), 96.5 ± 0.8% and 99.8 ± 0.1%, and 95.4 ± 0.6% and 99.4 ± 0.4% for the clinical prostate, rectum and anus plans respectively.ConclusionsA ZTE-based sCT algorithm with high dose accuracy throughout the pelvis has been developed. This suggests the algorithm is sufficiently accurate for MR-only radiotherapy for all pelvic sites.
Summary The ground conditions associated with old mineshafts are reviewed. Both the resistivity and magnetic geophysical methods have been applied to the search for old mineshafts. Magnetic methods are preferred because they can be applied to the occasionally difficult terrain conditions likely to be associated with disused shafts. Two case histories of the application of the magnetic method in the Newcastle upon Tyne area are given in detail.
Abstract Background Current automated planning solutions are calibrated using trial and error or machine learning on historical datasets. Neither method allows for the intuitive exploration of differing trade-off options during calibration, which may aid in ensuring automated solutions align with clinical preference. Pareto navigation provides this functionality and offers a potential calibration alternative. The purpose of this study was to validate an automated radiotherapy planning solution with a novel multi-dimensional Pareto navigation calibration interface across two external institutions for prostate cancer. Methods The implemented ‘Pareto Guided Automated Planning’ (PGAP) methodology was developed in RayStation using scripting and consisted of a Pareto navigation calibration interface built upon a ‘Protocol Based Automatic Iterative Optimisation’ planning framework. 30 previous patients were randomly selected by each institution (I A and I B ), 10 for calibration and 20 for validation. Utilising the Pareto navigation interface automated protocols were calibrated to the institutions’ clinical preferences. A single automated plan (VMAT Auto ) was generated for each validation patient with plan quality compared against the previously treated clinical plan (VMAT Clinical ) both quantitatively, using a range of DVH metrics, and qualitatively through blind review at the external institution. Results PGAP led to marked improvements across the majority of rectal dose metrics, with D mean reduced by 3.7 Gy and 1.8 Gy for I A and I B respectively ( p < 0.001). For bladder, results were mixed with low and intermediate dose metrics reduced for I B but increased for I A . Differences, whilst statistically significant ( p < 0.05) were small and not considered clinically relevant. The reduction in rectum dose was not at the expense of PTV coverage (D 98% was generally improved with VMAT Auto ), but was somewhat detrimental to PTV conformality. The prioritisation of rectum over conformality was however aligned with preferences expressed during calibration and was a key driver in both institutions demonstrating a clear preference towards VMAT Auto , with 31/40 considered superior to VMAT Clinical upon blind review. Conclusions PGAP enabled intuitive adaptation of automated protocols to an institution’s planning aims and yielded plans more congruent with the institution’s clinical preference than the locally produced manual clinical plans.
Ventricular tachycardia is an irregular heartbeat conventionally treated using invasive cardiac catheter ablation and medication. However, when standard treatments have been exhausted, cardiac SABR provides a final treatment option to this high-mortality condition. Complex diagnostic mapping and planning scans enable multi-disciplinary target delineation for a 25Gy single fraction. However, organs at risk (OAR) near the target make this treatment challenging to plan and deliver. Publications from cardiologists report the efficacy of cardiac SABR, however there is limited data on the treatment delivery and image matching of this complex procedure.
Acinetobacter baumannii is an opportunistic gram-negative bacterial pathogen that causes many nosocomial infections in immunocompromised individuals. Common infections include catheter-associated urinary tract infections, ventilator-associated pneumonia, skin and soft tissue infections, and bloodstream infections that often lead to septicemia. Increasing multidrug resistance (MDR) in A. baumannii warrants new approaches to understanding its virulence mechanisms and pathogenicity. As a first step in infection, A. baumannii can attach to host cells, providing a surface for the bacteria to grow and perhaps facilitating biofilm formation and subsequent tissue invasion. In this study, we evaluated antibiotic resistance and characterized biofilm formation, attachment, invasion, and surface protein RNA transcription profiles of A. baumannii clinical isolates. Some isolates were resistant to commonly prescribed antibiotics, with six of the seventeen showing MDR. We found that 16 of the 17 strains produce biofilms in varying amounts; all strains were able to adhere to and invade A549 pulmonary cells in high levels; and some of the strains exhibited genes associated with biofilm formation, attachment, and invasion. Levels of biofilm formation, attachment to A549 cells, and invasion of A549 were not associated with the presence or absence of target genes ompA, abaI, pga operon, bap, csuE, or blaPER-1. Virulence of A. baumannii clinical isolates increases due to their ability to produce biofilms and to attach to and invade host cells. It is important to elucidate further mechanisms of virulence in order to better treat A. baumannii infections and to prevent transmission and future outbreaks. We aimed to elucidate new information on the pathogenicity of A. baumannii that could lead to new therapeutic treatments for these infections.
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