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The Hounsfield unit (HU) scale is a linear transformation of the original linear attenuation coefficient measurement into one in which the radiodensity of distilled water at standard pressure and temperature is defined as 0 Hounsfield units (HU), while the radiodensity of air at STP is defined as −1000 HU.
A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. [2] The personnel that perform CT scans are called radiographers or radiology technologists.
This implies that two MIP renderings from opposite viewpoints are symmetrical images if they are rendered using orthographic projection. MIP is used for the detection of lung nodules in lung cancer screening programs which use computed tomography scans. MIP enhances the 3D nature of these nodules, making them stand out from pulmonary bronchi ...
Such an approach requires a large number of projections for each scan to obtain images with sufficient quality (in terms of artefacts and SNR). Hence, there is a clear trade-off between the rotation speed of the gantry (i.e. time resolution) and the quality of the reconstructed images.
The cannonball sign is a radiological term used to describe the presence of multiple, well-circumscribed, round opacities seen on X-ray or CT imaging, typically in the lungs. [1] This finding is most commonly associated with hematogenous metastases, where malignant cells spread to the lungs via the bloodstream, forming discrete nodules that ...
Modern detail-oriented scans such as high-resolution computed tomography (HRCT) is the gold standard in respiratory medicine and thoracic surgery for investigating disorders of the lung parenchyma . Contrasted CT scans of the chest are usually used to confirm diagnosis of for lung cancer and abscesses , as well as to assess lymph node status at ...
Low-dose high-resolution (1.25 mm) chest CT. HRCT is performed using a conventional CT scanner. However, imaging parameters are chosen so as to maximize spatial resolution: [1] a narrow slice width is used (usually 1–2 mm), a high spatial resolution image reconstruction algorithm is used, field of view is minimized, so as to minimize the size of each pixel, and other scan factors (e.g. focal ...
State of the art modern CT scanners with a scan rate of up to 320 mm/s can acquire all the images within a 1-second X-ray exposure, avoiding the problems of respiratory motion, cardiac motion and contrast draining from the pulmonary circulation during the study. Even though the actual scan may be completed in 1 second or less, considerable ...