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The currently used low dose CT scan results in a radiation exposure of about 2 millisieverts (equal to roughly 20 two-view chest x-rays). [11] It has been estimated that radiation exposure from repeated screening studies could induce cancer formation in a small percentage of screened subjects, so this risk should be mitigated by a (relatively ...
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.
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 ...
Quantitative CT scans are primarily used to evaluate bone mineral density at the lumbar spine and hip. In general, solid phantoms placed in a pad under the patient during CT image acquisition are used for calibration. These phantoms contain materials that represent a number of different equivalent bone mineral densities.
Contrast CT, or contrast-enhanced computed tomography (CECT), is X-ray computed tomography (CT) using radiocontrast. Radiocontrasts for X-ray CT are generally iodine-based types . [ 1 ] This is useful to highlight structures such as blood vessels that otherwise would be difficult to delineate from their surroundings.
Though CT uses a higher amount of ionizing x-radiation than diagnostic x-rays (both utilising X-ray radiation), with advances in technology, levels of CT radiation dose and scan times have reduced. [9] CT exams are generally short, most lasting only as long as a breath-hold, Contrast agents are also often used, depending on the tissues needing ...
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This has the potential reduce the amount of X-ray dose from a contrast scan by removing the need for a reference scan before contrast injection. Although spectral CT is already clinically available in the form of dual-energy scanners, photon-counting CT offers a number of advantages.