Cardiac Injury in COVID-19: A Systematic Review of Relevant Meta-Analyses.

Background: Cardiac injury (CI) is not a rare condition among hospitalized patients with coronavirus disease 2019 (COVID-19). Its prognostic value has been extensively reported through the literature, mainly in the context of observational studies. An impressive number of relevant meta-analyses has been conducted.

Thromboprophylaxis in Patients with COVID-19: Systematic Review of National and International Clinical Guidance Reports.

Background: Venous Thromboembolism (VTE) is common among patients with severe Coronavirus Disease 2019 (COVID-19). Anticoagulation in hospitalized COVID-19 patients has been associated with survival benefit; however, the optimal thromboprophylaxis strategy has not yet been defined.

Objective: To identify published guidance reports by national and international societies regarding thromboprophylaxis strategies in COVID-19 patients in different settings (outpatients, hospitalized, post-discharge).

Venous thromboembolism in the era of COVID-19.

Coronavirus disease 2019 (COVID-19) does not only affect the respiratory system but appears to be a systemic disease. Venous thromboembolism is a common manifestation in hospitalized patients with COVID-19 with a reported incidence that is significantly higher compared to other acute viral infections. The pathophysiology mechanisms have not been fully explored and autopsy studies might enhance our understanding on this topic.

Monte Carlo reference data sets for imaging research: Executive summary of the report of AAPM Research Committee Task Group 195.

The use of Monte Carlo simulations in diagnostic medical imaging research is widespread due to its flexibility and ability to estimate quantities that are challenging to measure empirically. However, any new Monte Carlo simulation code needs to be validated before it can be used reliably. The type and degree of validation required depends on the goals of the research project, but, typically, such validation involves either comparison of simulation results to physical measurements or to previously published results obtained with established Monte Carlo codes.

Floppy eyelid syndrome: the coventry experience.

Purpose: Floppy eyelid syndrome is a condition that is difficult to identify and diagnose and with no clear guidelines on its management. We propose a method of reliably grading this syndrome and have proposed a management algorithm based on the grading.

Materials And Methods: Retrospective data collection of patients diagnosed with Floppy eyelid syndrome and treated under the care of a single oculoplastic surgeon over a 9 year period.

Evaluation of clinical full field digital mammography with the task specific system-model-based Fourier Hotelling observer (SMFHO) SNR.

Purpose: The purpose of this work is to evaluate the performance of the image acquisition chain of clinical full field digital mammography (FFDM) systems by quantifying their image quality, and how well the desired information is captured by the images.

Methods: The authors present a practical methodology to evaluate FFDM using the task specific system-model-based Fourier Hotelling observer (SMFHO) signal to noise ratio (SNR), which evaluates the signal and noise transfer characteristics of FFDM systems in the presence of a uniform polymethyl methacrylate phantom that models the attenuation of a 6 cm thick 20/80 breast (20% glandular/80% adipose). The authors model the system performance using the generalized modulation transfer function, which accounts for scatter blur and focal spot unsharpness, and the generalized noise power spectrum, both estimated with the phantom placed in the field of view.

Material-specific transfer function model and SNR in CT.

This study presents an analytical model for the edge spread function (ESF) of a clinical CT system that allows reliable fits of noisy ESF data. The model was used for the calculation of the material-specific transfer function TF and an estimation of the signal transfer and the signal-to-noise ratio (SNR) in 2D. Images of the Catphan phantom were acquired with a clinical Siemens Somatom Sensation Cardiac 64 CT scanner combining four different x-ray tube outputs (40, 150, 250 and 350 mAs) with four different reconstruction filters, which covered the range from very smooth (B10s) to very sharp (B70s).

Reducing radiation dose to the female breast during CT coronary angiography: a simulation study comparing breast shielding, angular tube current modulation, reduced kV, and partial angle protocols using an unknown-location signal-detectability metric.

Purpose: The authors compared the performance of five protocols intended to reduce dose to the breast during computed tomography (CT) coronary angiography scans using a model observer unknown-location signal-detectability metric.

Methods: The authors simulated CT images of an anthropomorphic female thorax phantom for a 120 kV reference protocol and five "dose reduction" protocols intended to reduce dose to the breast: 120 kV partial angle (posteriorly centered), 120 kV tube-current modulated (TCM), 120 kV with shielded breasts, 80 kV, and 80 kV partial angle (posteriorly centered). Two image quality tasks were investigated: the detection and localization of 4-mm, 3.

Monte Carlo study of the effects of system geometry and antiscatter grids on cone-beam CT scatter distributions.

Purpose: The proliferation of cone-beam CT (CBCT) has created interest in performance optimization, with x-ray scatter identified among the main limitations to image quality. CBCT often contends with elevated scatter, but the wide variety of imaging geometry in different CBCT configurations suggests that not all configurations are affected to the same extent. Graphics processing unit (GPU) accelerated Monte Carlo (MC) simulations are employed over a range of imaging geometries to elucidate the factors governing scatter characteristics, efficacy of antiscatter grids, guide system design, and augment development of scatter correction.

A database for estimating organ dose for coronary angiography and brain perfusion CT scans for arbitrary spectra and angular tube current modulation.

Purpose: The purpose of this study was to develop a database for estimating organ dose in a voxelized patient model for coronary angiography and brain perfusion CT acquisitions with any spectra and angular tube current modulation setting. The database enables organ dose estimation for existing and novel acquisition techniques without requiring Monte Carlo simulations.

Methods: The study simulated transport of monoenergetic photons between 5 and 150 keV for 1000 projections over 360° through anthropomorphic voxelized female chest and head (0° and 30° tilt) phantoms and standard head and body CTDI dosimetry cylinders.

Signal detection and location-dependent noise in cone-beam computed tomography using the spatial definition of the Hotelling SNR.

Purpose: Quality assurance in computed tomography (CT) is commonly performed with the Fourier-based modulation transfer function (MTF) and the noise variance, while more recently the noise power spectrum (NPS) has increased in popularity. The Fourier-based methods make assumptions such as shift-invariance and cyclostationarity. These assumptions are violated in real clinical systems and consequently are expected to result in systematic errors.

TU-E-217BCD-01: X-Ray Spectra for Breast CT.

Purpose: To study a range of x-ray spectra with regard to their suitability for dedicated breast CT, taking into account realistic tube loading limitations.

Methods: A simple theoretical model was used to get a preliminary indication of the best mono-energetic x-ray energy as a function of object size. That model was extended to poly-energetic spectra and used to study a range of object sizes, tube voltages, filter materials, and filter thicknesses.

Alfentanil sedation for oculoplastic surgery: the patient experience.

Purpose: A number of agents have previously been reported to be safe and effective for sedation and analgesia in ophthalmic surgery under local anaesthesia, but there has been no previous patient-focused assessment of this form of conscious sedation. We present a patient satisfaction survey, including a validated pain score, for patients undergoing oculoplastic procedures under local anaesthesia with alfentanil sedation.

Methods: A prospective, non-randomized, questionnaire-based study of the experience, satisfaction and pain scores of consecutive patients undergoing oculoplastic procedures under local anaesthesia with alfentanil sedation at University Hospital, Coventry, UK, under the care of one Consultant Oculoplastic Surgeon between 2006 and 2009.

Computational high-resolution heart phantoms for medical imaging and dosimetry simulations.

Cardiovascular disease in general and coronary artery disease (CAD) in particular, are the leading cause of death worldwide. They are principally diagnosed using either invasive percutaneous transluminal coronary angiograms or non-invasive computed tomography angiograms (CTA). Minimally invasive therapies for CAD such as angioplasty and stenting are rendered under fluoroscopic guidance.

Periorbital Masson's tumor: a case series.

Intravascular papillary endothelial hyperplasia (IPEH) or Masson's tumor is an unusual variety of benign vascular tumor. Involvement of periorbital area is uncommon. We report 2 cases of periorbital IPEH and review relevant literature.

penMesh--Monte Carlo radiation transport simulation in a triangle mesh geometry.

We have developed a general-purpose Monte Carlo simulation code, called penMesh, that combines the accuracy of the radiation transport physics subroutines from PENELOPE and the flexibility of a geometry based on triangle meshes. While the geometric models implemented in most general-purpose codes--such as PENELOPE's quadric geometry--impose some limitations in the shape of the objects that can be simulated, triangle meshes can be used to describe any free-form (arbitrary) object. Triangle meshes are extensively used in computer-aided design and computer graphics.

Singular value description of a digital radiographic detector: theory and measurements.

The H operator represents the deterministic performance of any imaging system. For a linear, digital imaging system, this system operator can be written in terms of a matrix, H, that describes the deterministic response of the system to a set of point objects. A singular value decomposition of this matrix results in a set of orthogonal functions (singular vectors) that form the system basis.

Vitreous loss during phacoemulsification in glaucoma patients: long-term intraocular pressure control.

Purpose: To assess the long-term effect of vitreous loss during phacoemulsification on intraocular pressure (IOP) control in glaucoma patients.

Setting: Birmingham and Midland Eye Centre, City Hospital, Birmingham, United Kingdom.

Methods: In this study, 26 glaucoma cases with vitreous loss during phacoemulsification were identified from operative room records.

Anisotropic imaging performance in breast tomosynthesis.

We describe the anisotropy in imaging performance caused by oblique x-ray incidence in indirect detectors for breast tomosynthesis based on columnar scintillator screens. We use MANTIS, a freely available combined x-ray, electron, and optical Monte Carlo transport package which models the indirect detection processes in columnar screens, interaction by interaction. The code has been previously validated against published optical distributions.

Monte Carlo simulation of a realistic anatomical phantom described by triangle meshes: application to prostate brachytherapy imaging.

Purpose: Monte Carlo codes can simulate the transport of radiation within matter with high accuracy and can be used to study medical applications of ionising radiations. The aim of our work was to develop a Monte Carlo code capable of generating projection images of the human body. In order to obtain clinically realistic images a detailed anthropomorphic phantom was prepared.