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However, coronal images require the person to hyperextend their neck, which must be avoided if any possibility of neck injury exists. [8] CT scans of the head increase the risk of brain cancer, especially for children. As of 2018, it appeared that there was a risk of one excess cancer per 3,000–10,000 head CT exams in children under the age ...
Fig.1: Basic principle of tomography: superposition free tomographic cross sections S 1 and S 2 compared with the (not tomographic) projected image P Median plane sagittal tomography of the head by magnetic resonance imaging. Tomography is imaging by sections or sectioning that uses any kind of penetrating wave.
A CT scan can be performed in under a second and produce rapid results for clinicians, with its ease of use leading to an increase in CT scans performed in the United States from 3 million in 1980 to 62 million in 2007. Clinicians oftentimes take multiple scans, with 30% of individuals undergoing at least 3 scans in one study of CT scan usage. [36]
Of the CT scans, six to eleven percent are done in children, [168] an increase of seven to eightfold from 1980. [167] Similar increases have been seen in Europe and Asia. [167] In Calgary, Canada, 12.1% of people who present to the emergency with an urgent complaint received a CT scan, most commonly either of the head or of the abdomen.
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 ...
Traditionally CT and MRI scans produced 2D static output on film. To produce 3D images, many scans are made and then combined by computers to produce a 3D model, which can then be manipulated by the physician. 3D ultrasounds are produced using a somewhat similar technique. In diagnosing disease of the viscera of the abdomen, ultrasound is ...
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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]