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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.
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 ...
Quantitative computed tomography (QCT) is a medical technique that measures bone mineral density (BMD) using a standard X-ray computed tomography (CT) scanner with a calibration standard to convert Hounsfield units (HU) of the CT image to bone mineral density values. [1]
The Hounsfield unit (HU) scale is a linear transformation of the original linear attenuation coefficient measurement into one in which the radiodensity of distilled water at standard pressure and temperature is defined as 0 Hounsfield units (HU), while the radiodensity of air at STP is defined as −1000 HU.
X-ray computed tomography (CT), or Computed Axial Tomography (CAT) scan, is a helical tomography technique (latest generation), which traditionally produces a 2D image of the structures in a thin section of the body. In CT, a beam of X-rays spins around an object being examined and is picked up by sensitive radiation detectors after having ...
The computed tomography dose index (CTDI) is a commonly used radiation exposure index in X-ray computed tomography (CT), first defined in 1981. [1] [2] The unit of CTDI is the gray (Gy) and it can be used in conjunction with patient size to estimate the absorbed dose.
The Haller index, created in 1987 by J. Alex Haller, S. S. Kramer, and S. A. Lietman, [1] is a mathematical relationship that exists in a human chest section observed with a CT scan. It is defined as the ratio of the transverse diameter (the horizontal distance of the inside of the ribcage ) and the anteroposterior diameter (the shortest ...
The Agatston score, named after its developer Arthur Agatston, is a measure of calcium on a coronary CT calcium scan. [7] The original work, published in 1990, [8] was based on electron beam computed tomography (also known as ultrafast CT or EBCT). The score is calculated using a weighted value assigned to the highest density of calcification ...