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Computed tomography
Published in Ken Holmes, Marcus Elkington, Phil Harris, Clark's Essential Physics in Imaging for Radiographers, 2021
Hounsfield scaleIs based on air as the reference value of 0Is based on water as the reference value of 0Is based on bone as the reference value of 0Is based on metal as the reference value of 0.
Management of osteoporotic proximal humeral fractures
Published in Peter V. Giannoudis, Thomas A. Einhorn, Surgical and Medical Treatment of Osteoporosis, 2020
Osteoporosis cannot be defined in the acute situation. It is, however, important for the surgeon to have an idea about bone quality and hence of the stability of the osteosynthesis. A correlation exists between cortical thickness of the proximal humeral shaft and bone mineral density. A CT scan can be used to define bone density using the Hounsfield scale (8,9).
Computerized Tomography, Xeroradiography, Lymphography, and Xerolymphography in Diagnosis of Lymph Stasis
Published in Waldemar L. Olszewski, Lymph Stasis: Pathophysiology, Diagnosis and Treatment, 2019
The extremities are examined in the supine position using a Somatom 2 set (Siemens). A slice thickness is 4 or 8 mm with a scanning time of 5 s. The image is recorded on a diskette for later analysis. For contrast medium we use Iopamidol Bracco or Verografin Spofa 60%, 40 cc intravenously in the seconds of computerized tomographic slices. Both legs are examined side-to-side to eliminate the changes that normally occur in the muscular tissue distribution in the different parts of the leg. Tissue density measurements are made at different points in subcutaneous and muscular tissues and recorded using the Hounsfield scale and region of interest. A histogram of subcutaneous tissue also is analyzed. The edemas are objectively evaluated by measuring the thickness of the skin, subcutis, and extremity diameter. It is possible to estimate the volume of the tissue compartments from the cross-sectional areas the images recorded on normal X-ray films. We measure the diameter of extremity; the thickness of the skin, subcutis, and muscle compartment in millimeters; and the area of extremity in the slice investigated in square millimeters.
Neuroanniversary 2022
Published in Journal of the History of the Neurosciences, 2022
In 1972, the first clinical test of computer-assisted tomography scanning (CAT) was performed successfully. Sir Godfrey Newbold Hounsfield (1919–2004), an English electrical engineer born in Newark, Nottinghamshire, was essential in the development of CAT. He was awarded the 1979 Nobel Prize for Physiology or Medicine and was knighted in 1981. His name will be remembered in the eponym “the Hounsfield scale,” which is a quantitative measure of radiodensity used in evaluating CT scans.
Lipomatous pancreas facilitates late onset of renal cell carcinoma metastases
Published in Acta Chirurgica Belgica, 2021
T. Fahlbusch, A. M. Luu, C. Braumann, C. Lukas, W. Uhl, B. M. Künzli
Data were collected retrospectively at the St. Josef-Hospital, University-Hospital of the Ruhr-University Bochum, Bochum, Germany. We enrolled all patients that underwent surgery for PaMet derived from RCC between 2006 and 2018 in the study, using in-house electronic documentation services. All findings were confirmed histopathologically. Data about demographics, clinical symptoms, tumor specifications, radiological findings, surgical peri- and postoperative complications were evaluated (see Table 1). The St. Josef-Hospital is a high volume centre with more than 300 pancreatic operations (>200 resections) per year. All operations were performed by experienced senior surgeons. Follow-up information about survival times and comorbidities were conducted by internal monitoring for up to 48 months. Statistical data were analysed with SPSS V21.0 (SPSS Inc., Chicago, Ill, USA). Univariate analyses were performed using Mann–Whitney-U and Kruskal–Wallis-tests. Post hoc tests were calculated using ANOVA (Kruskal–Wallis-test). Postoperative complications and pancreatic fistulas (POPF) were evaluated according to the classification of Clavien-Dindo et al. and the ISGPF [5,6]. Computer tomography (CT) measurements were performed in portal venous phase and analyzed with the JiveX Demonstration Client (VISUS Health IT GmbH, Bochum, Germany). Pancreatic, splenic and subcutaneous fat densities were evaluated by using the Hounsfield scale. In CT any tissue can be measured in contrast to air and water. Resulting Hounsfield units (HU) are comparable [7]. Examinations were made using various thin-layer CTs and enhancement in the venous phase. In order to improve statistical validity, HU values of every pancreas were measured in the head, body and tail in non-tumorous tissue. Therefore, three data points were collated for each pancreas. As the spleen is ‘fat-free’, HU values were compared to splenic densities. Furthermore, the pancreatic results were compared to subcutaneous abdominal fat. In both cases, ratios (pancreas-to-spleen and pancreas-to-fat) were calculated [8].
Bulk Fill flow resin contraction using 3D finite element model and calibration by Fiber Bragg Grating measurement
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
Claudio Antunes Junior, Emílio Graciliano Ferreira Mercuri, Ana Paula Gebert de Oliveira Franco, Manoella Costa, Leandro Zen Karam, Hypolito José Kalinowski, Osnara Maria Mongruel Gomes
The reconstruction initiated with the software InVesalius, using the Hounsfield scale, being able to differentiate the materials that are part of the tooth. First, the material surfaces were selected individually and then a 3 D model was saved in STL (stereolithography) format.