Glossary Terms

Question 1

180-degree linear interpolation

Answer 1

Type of algorithm use for multi slice computed tomography image reconstruction in which data acquired from a shorter distance away from the reconstructed slice location are interpolated

Question 2

360 degree linear interpolation

Answer 2

Type of algorithm to use for multi slice computed tomography image reconstruction in which two sets of projection #DATA acquired 360° apart are used to form an image as precise z-axis location

Question 3

The amount of x-ray energy absorbed in a unit of mass

it is measured in grays (Gy)

Answer 3

Absorbed dose

Question 4

The ability of an individual CT detector to absorb and measure the transmitted Xray intensity incident upon it primarily controlled by the characteristics and physical make up of the detector and material

Answer 4

Absorption efficiency

Question 5

The type of multi scan computed tomography detector array configured with the thinnest detectors at the center surrounded by detectors of incrementally increasing widths along the Z-axis

Answer 5

Adaptive array

Question 6

Cone beam correction algorithm utilize to overcome potential attenuation calculation errors from the divergent beam of multi scan computed tomography systems

Answer 6

Advanced single-slice rebinning algorithm (ASSR)

Question 7

The tendency of scintillation type CT detector to continue to glow in response to x radiation after the exposure source has been terminated

Answer 7

Afterglow

Question 8

Quantification of the volume and density of calcium within the coronary arteries as calculated during a CT coronary artery calcification examination the score is used to indicate a patient’s risk of suffering a cardiac event

Answer 8

Agatston score

Question 9

Acronym for as low as reasonably achievable the cardinal principle of radiation dose reduction for all radiologic procedures including city

Answer 9

ALARA

Question 10

Mathematical filter applied to raw data during CT image reconstruction to remove blurring artifact inherent to back projection may also be referred to as a kernel

Answer 10

Algorithm

Question 11

A form of streak artifact caused by an insufficient number of views obtained during data acquisition

Answer 11

Aliasing

Question 12

A component of the data acquisition system (DAS)responsible for converting the electronica signal emitted by the CT detectors into digital form

Answer 12

Analog to digital converter (ADC)

Question 13

The storage a CT data in either hard film or soft digital form

Answer 13

Archival

Question 14

A 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

Answer 14

Array Processor (AP)

Question 15

Period of peak arterial enhancement after the bolus IV administration of Iodinated contrast material

Answer 15

Arterial phase

Question 16

What arterial phase occurs approximately 25 to 35 seconds after the initiation of contrast agent administration

Answer 16

Hepatic

Question 17

A form of noise on the CT image resulting from errors during the measurement of transmitted radiation by the detectors

Answer 17

Artifact

Question 18

A neurologic sign characterized by loss of muscular coordination

Answer 18

Ataxia

Question 19

The reduction in intensity of a radiation beam as it passes through a substance

Answer 19

Attenuation

Question 20

The value assigned to an object quantifying its ability to attenuate an x-ray beam

Answer 20

Attenuation coefficient

Question 21

CT system software used to adjust the milliamperage (mA)throughout an acquisition to reduce patient radiation does to a minimum

Answer 21

Automatic tube current modulation ( ATCM)

Question 22

CT system software used to adjust the tube voltage (Kvp) based upon the changing patient attenuation along the scan acquisition range to reduce patient radiation does to a minimum

Answer 22

Automatic tube voltage selection (ATVS)

Question 23

The mathematical process of CT image reconstruction whereby ray sun data are projected back onto a matrix

Answer 23

Back-projection

Question 24

The phenomenon whereby low energy photons are absorbed as the x-ray beam passes through an object resulting in an increase in the average photon energy of the beam

Answer 24

Beam hardening

Question 25

The ratio of table feed per gantry rotation to the total collimation use during acquisition with a multi scan CT system

Answer 25

Beam pitch

Question 26

The dimension of the primary beam in the longitudinal z-axis as controlled by the pre-patient collimator

Answer 26

Beam width

Question 27

The process of electronically combining signal from adjacent detector elements to provide a reconstructed CT image that is thicker than the individual detector width

Answer 27

Binning

Question 28

The number of information bits that is contained within each pixel

Answer 28

Bit depth

Question 29

A measurement of renal function determined as the amount of nitrogen in the blood in the form of the waste product area

Answer 29

Blood urea nitrogen (BUN)

Question 30

What is the normal range of BUN in adults

Answer 30

7-25 mg/dL

Question 31

A type of filter added to the CT x-ray tube to compensate for the cylindrical shape of most body parts the filter is thicker at the ends and help shape the beam to reduce patient radiation exposure

Answer 31

Bow-tie filter