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CT Terminology
Understanding the lingo :)
Term | Definition |
---|---|
180-Degree linear interpolation (180LI) | Type of algorithm used for MSCT image reconstruction in which data is acquired from a shorter distance (180 degrees) away from the reconstructed slice location are interpolated. |
360-Degree linear interpolation (360LI) | Type of algorithm used for MSCT image reconstruction in which two sets of projection data acquired 360 degrees apart are used to form an image at a precise z-axis location. |
Absorbed dose | The amount of x-ray energy absorbed in a unit of mass. Measured in grays (Gy). |
Absorption Efficiency | The ability of an individual CT detector to absorb and measure the transmitted x-ray intensity incident upon it. Primarily controlled by the characteristics and physical makeup of the detector material. |
Adaptive Array | The type of MSCT detector array configured with the thinnest detectors at the center, surrounded by detectors of incrementally increasing widths along the z-axis. |
Advanced single-slice rebinning (ASSR) algorithm | Cone beam correction algorithm utilized to overcome potential attenuation calculation errors from the divergent beam of MSCT systems. |
Afterglow | The tendency of a scintillation-type CT detector to continue to glow in response to x-radiation after the exposure source has been terminated. |
Agatston Score | Quantification of the volume and density of calcium within the coronary arteries. As calculated during a CT coronary calcification (CAC) examination; the Agatston score is used to indicate a patient's risk of suffering a cardiac event. |
ALARA | Acronym for As Low As Reasonably Achievable; the cardinal principle of radiation dose reduction for all radiologic procedures, including CT. |
Algorithm | Mathematical filter applied to raw data during CT image reconstruction to remove blurring artifact inherent to back-projection. May also be referred to as "kernel." |
Aliasing | A form of streak artifact caused by an insufficient number of views (data samples) obtained during data acquisitions. |
Analog-to-digital-converter (ADC) | Component of the data acquisition system (DAC) responsible for converting the electronic signal emitted by the CT detectors into digital form. |
Archival | The storage of CT data in either hard (film) or soft (digital) form. |
Array Processor (AP) | Component of the CT computer system responsible for receiving raw scan data, performing all of the major processing of the CT image, and returning the reconstructed image to the storage memory of the host computer. |
Arterial Phase |