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CT scans can be performed with different settings for lower exposure in children with most manufacturers of CT scans as of 2007 having this function built in. [170] Furthermore, certain conditions can require children to be exposed to multiple CT scans. [148] Current recommendations are to inform patients of the risks of CT scanning. [171]
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 ...
Such scans are most useful for tissues outside the brain, where location of tissues may be far more variable. For example, SPECT/CT may be used in sestamibi parathyroid scan applications, where the technique is useful in locating ectopic parathyroid adenomas which may not be in their usual locations in the thyroid gland. [14]
For example, because MRI has only been in use since the early 1980s, there are no known long-term effects of exposure to strong static fields (this is the subject of some debate; see 'Safety' in MRI) and therefore there is no limit to the number of scans to which an individual can be subjected, in contrast with X-ray and CT. However, there are ...
CT angiography is a contrast CT taken at the location and corresponding phase of the blood vessels of interest, in order to detect vascular diseases. For example, an abdominal aortic angiography is taken in the arterial phase in the abdominal level, and is useful to detect for example aortic dissection .
high strength (0.15 to 1.5 teslas) [4] are used to excite protons that produce the record results (like CT scan). It can show particular tissues more clearly than CT.; [4] video link: Linear accelerator: used in radiotherapy for cancer: Functional magnetic resonance imaging (fMRI) video link: Positron emission tomography (PET Scan) video link
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.
Computed tomography or CT scan (previously known as CAT scan, the "A" standing for "axial") uses ionizing radiation (x-ray radiation) in conjunction with a computer to create images of both soft and hard tissues. These images look as though the patient was sliced like bread (thus, "tomography" – "tomo" means "slice").