![]() We sought to determine if changing HU threshold and adding absolute percent contrast washout (APW) criteria would identify adrenal adenomas better than current recommendations. This monograph is a valuable study on computed tomography that will be of interest to advanced students and researchers in the fields of biomedical engineering, medical electronics, computer science and medicine. Background: Current recommendations using Hounsfield units (HU) 10 to identify adrenal adenomas on unenhanced computed tomography (CT) miss 10-40 of benign adenomas. The absorption/attenuation coefficient of radiation within a tissue is used during CT reconstruction to produce a grayscale image. The information included in this chapter will enable readers to create a simulation environment in which virtual tomography projections can be obtained in all basic projection systems. Excerpt The Hounsfield unit (HU) is a relative quantitative measurement of radio density used by radiologists in the interpretation of computed tomography (CT) images. Tissues with high x-ray attenuation (such as bone. Tissues with low attenuation (such as air and fat) have a low HU number. A spectrum of gray tones is generated, from -1000 to +3000 (note: the upper limit is determined by the scanner type). These differences are converted into ‘CT numbers’, better known as Hounsfield units (HU). The author gives descriptions of the reconstruction methods related to tomography scanners with a parallel X-ray beam, trough solutions with fan-shaped beam and successive modifications of spiral scanners.Ĭomputed Tomography contains a dedicated chapter for those readers who are interested in computer simulations based on studies of reconstruction algorithms. The degree of x-ray attenuation depends on the tissue type. It discusses X-ray CT tomography from a historical point of view, the design and physical operating principles of computed tomography apparatus, the algorithms of image reconstruction and the quality assessment criteria of tomography scanners.Īlgorithms of image reconstruction from projections, a crucial problem in medical imaging, are considered in depth. ![]() operating voltage to calculate dose to an object in terms of Hounsfield units. Computed Tomography gives a detailed overview of various aspects of computed tomography. The CT Reconstruction tool offers a variety of algorithms and filters for. ![]()
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