Experiencing COVID-19 at a large district level hospital in Cape Town: A retrospective analysis of the first wave.

Background: The coronavirus disease 2019 (COVID-19) pandemic in tertiary hospitals from South Africa and world wide have been well described, but limited data are published on the findings. This article aimed to describe patients admitted to a large district hospital in Cape Town, South Africa, during the first wave of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Infections. To compare the clinical features and further investigate survivors and deceased COVID-19 patients. Methods: A single centre retrospective review of clinical records and laboratory data of patients admitted with a positive SARS-CoV-2 polymerase chain reaction (PCR) from April 2020 to August 2020. Results: A total of 568 patients with a positive SARS-CoV-2 PCR were admitted to the study centre for one night or longer and of these patients 154 (27%) died of COVID-19. The median age of patients who died of COVID-19 was 66 years and 53 years for survivors. Hypertension, diabetes mellitus and obesity were the commonest comorbidities in patients who survived and died of COVID-19. There were no major differences when comparing the severity of infiltrates on chest X-rays (CXR) of COVID-19 survivors with deceased patients. More than half (58%) of deceased patients died within 3 days following admission to hospital. A substantial number of patients who died of COVID-19 had associated acute kidney injury (n = 79, 51%). Conclusion: Acute kidney injury had a high prevalence amongst patients who died of COVID-19. Delays in transfer to intensive care unit (ICU), limited ICU capacity and disease severity contributed to a substantial number of patients dying within 3 days of admission.

A linear array silicon pixel detector: images of a mammographic test object and evaluation of delivered doses.

We present images of a mammographic test object obtained using a linear array silicon pixel detector capable of single-photon counting. The detector pixel size was 200 x 300 microns2 and images were acquired by scanning the test object between the laminar detector and the x-ray source with a scanning step of 100 microns. A molybdenum anode tube was used with two different filtrations: 2 mm aluminium and 25 microns molybdenum. Conventional film-screen images were also obtained in order to compare spatial and contrast resolution. In our digital images it is possible to recognize low-contrast details having dimensions smaller than or equal to the dimensions of details visible by means of a clinical mammographic unit. The detection of microcalcifications smaller than 150 microns was possible only when using the Mo filtration. However a copper wire of 50 microns diameter was detectable when embedded in a simulated tissue. We discuss in detail the mean glandular doses (MGDs) delivered during the image acquisition. The MGDs necessary to obtain good-quality images are always smaller than at a conventional mammographic unit. Since MGDs depend on the x-ray spectrum, the dose reduction becomes larger when the applied spectrum is harder than in film-screen acquisition (Al filtration and 35 kVp).

Mammography with synchrotron radiation: phase-detection techniques.

The authors evaluated the effect on mammographic examinations of the use of synchrotron radiation to detect phase-perturbation effects, which are higher than absorption effects for soft tissue in the energy range of 15-25 keV. Detection of phase-perturbation effects was possible because of the high degree of coherence of synchrotron radiation sources. Synchrotron radiation images were obtained of a mammographic phantom and in vitro breast tissue specimens and compared with conventional mammographic studies. On the basis of grades assigned by three reviewers, image quality of the former was considerably higher, and the delivered dose was fully compatible.