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However, a lumbar spine X-ray has a similar dose as a head CT. [150] Articles in the media often exaggerate the relative dose of CT by comparing the lowest-dose X-ray techniques (chest X-ray) with the highest-dose CT techniques. In general, a routine abdominal CT has a radiation dose similar to three years of average background radiation. [151]
It has a greater ionizing radiation dose burden than projection radiography; repeated scans must be limited to avoid health effects. CT is based on the same principles as X-ray projections but in this case, the patient is enclosed in a surrounding ring of detectors assigned with 500–1000 scintillation detectors [13] (fourth-generation X-ray ...
The data can be corrected for self-absorption artefacts using an X-ray absorption-contrast CT scan of the same sample. If the solid-state chemistry of the sample is changing during the XRD-CT scan, then other data acquisition approaches can be employed that can improve the temporal resolution of the method, such as the interlaced approach [13] [14]
Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object.Applications of radiography include medical ("diagnostic" radiography and "therapeutic radiography") and industrial radiography.
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 ...
This can either be used to increase the image quality at the same X-ray exposure level, or to lower the patient X-ray dose whilst maintaining the same image quality. Second, it is difficult to manufacture energy-integrating detectors with smaller pixel size than approximately 1×1 mm 2 without compromising dose efficiency.
The images may also be used to check for other requirements of some types of treatment, such as full or empty bladder, empty rectum, etc. [8] [27] The same cone beam beam source and detector can alternatively be used to take simple X-ray positioning images if the organ shows particularly well on X-ray or if Fiducial markers have been inserted ...
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 ...