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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.
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.
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 ...
Aspirin in men 45 to 79 and women 55 to 79 for cardiovascular disease; Colon cancer screening by colonoscopy, occult blood testing, or sigmoidoscopy in adults 45 to 75. [11] Low-dose CT scans for adults 55 to 80 at increased risk of lung cancer; Osteoporosis screening via bone dual-energy X-ray absorptiometry (DEXA) in women over 65
Most radiation therapy is planned using the results of a 3D CT scan. A 3D scan largely presents a snapshot of the body at a particular point in time, however due to the time of the acquisition, in which the patient is likely to have moved in some way (even if only breathing), there will be an element of blurring or averaging in the 3D scan. [ 6 ]
“The dose is really dependent on the patient.” Until more research is done, the jury is still out on whether the general population would benefit from taking daily aspirin to prevent colon cancer.
As an example, each mm 2 of a CT detector may receive several hundred million photon interactions per second during a scan. [ 4 ] To avoid saturation in areas where little material is present between the X-ray source and the detector, the pulse resolving time must be small compared to the average time between photon interactions in a pixel.