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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 ...
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 risks of CT scan radiation are especially important in patients undergoing recurrent CT scans within a short time span of one to five years. [ 157 ] [ 158 ] [ 159 ] Some experts note that CT scans are known to be "overused," and "there is distressingly little evidence of better health outcomes associated with the current high rate of scans."
For reference, current coronary artery angiography imaging is usually performed at 30 frames/second or 0.033 seconds/frame; EBT is far closer to this than mechanically swept CT machines. Signal-to-noise ratio and spatial resolution are also worse compared to conventional CT. [3]
In conventional CT machines, an X-ray tube and detector are physically rotated behind a circular shroud (see the image above right). An alternative, short lived design, known as electron beam tomography (EBT), used electromagnetic deflection of an electron beam within a very large conical X-ray tube and a stationary array of detectors to achieve very high temporal resolution, for imaging of ...
SPECT visualized by a MIP of a mouse Types of presentations of CT scans: - Average intensity projection - Maximum intensity projection - Thin slice (median plane)- Volume rendering by high and low threshold for radiodensity.
The partial volume effect can be defined as the loss of apparent activity in small objects or regions because of the limited resolution of the imaging system. It occurs in medical imaging and more generally in biological imaging such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT).
Cone-beam spiral computed tomography (CT) is a medical imaging technology that has impacted healthcare since its development in the early 1990s. [1] [2] This technology offers advancements over traditional fan-beam CT, including faster scanning speed, higher image quality, and the ability to generate true three-dimensional volumes, even with contrast-enhancement.