Computed Tomography

Question 1

The number of photons absorbed by the detector and dependent on the physical properties of the detector face

Answer 1

Absorption Efficiency

Question 2

Filter the x-ray beam to reduce the radiation to the patient and help minimize image artifact and improve quality

Answer 2

Compensating filters

Question 3

Dose Reported to the FDA

Answer 3

Computed Tomography Dose Index (CTDI)

Question 4

Elements in a CT system that collect attenuation information and measures the intensity of the transmitted x-ray radiation along beam projected from the x-ray source to that particular detector element

Answer 4

Detector

Question 5

A direct plane is one that can be obtained by positioning the patient in a specific position

Answer 5

Direct Axial Plane

Question 6

A technique for expressing a waveform as a weighted sum of sines and cosines

Answer 6

Discrete Fourier Transform (DFT)

Question 7

A technique of interpolating helical scan data for SDCT systems using the 360° linear interpolation

Answer 7

360° Linear Interpolation

Question 8

Process of Moving the table by a specific measure

Answer 8

Table Incrementation

Question 9

An acute Impairment of renal function that follows the intravascular administration of contrast material for which alterations causes have been excluded

Answer 9

Contrast media-induced Nephropathy (CIN)

Question 10

Scanner Configuration that consists of a detector array and an x-ray tube that produces a fan shaped beam that covers the entire field of view and a detector array

Answer 10

third generation design

Question 11

It is determined how rapidly data are acquired and is controlled by gantry rotation speed, the number of detector channels in the system, and the speed with which the system can record changing signals.

Answer 11

Temporal Resolution

Question 12

When the table position is manually set at zero by the technologist

Answer 12

Table Referencing

Question 13

The difference between the measured CT number of a given tissue and the known value for that tissue

Answer 13

System Noise

Question 14

Low-voltage electrical contacts within the gantry designed to allow continuous rotation of an x-ray tube without the use of cables connecting internal and external components

Answer 14

Slip rings

Question 15

Detector rows that have variable widths and sizes

Answer 15

Adaptive / Nonuniform / Hybrid array

Question 16

Determines the extent a patient can be scanned without repositioning

Answer 16

Scannable range

Question 17

Size of detector opening

Answer 17

Detector aperture

Question 18

Entire collection of detectors included in a CT system

Answer 18

Detector array

Question 19

• Ability of a system to resolve, as separate form, small objects that are very close together.
• also call high contrast resolution or detail resolution

Answer 19

Spatial Resolution

Question 20

electromechanical devices that use a brushlike apparatus to provide continuous electrical power and electronic communication across a rotating surface, permitting the gantry frame to rotate continuously, eliminating the need to straighten twister system cables

Answer 20

Slip Rings

Question 21

The leakage of fluid from a vein into the surrounding tissue during IV contrast administration

Answer 21

Contrast Media Extravasation

Question 22

Process used to generate three-dimensional images that show the surface of a three-dimensional object

Answer 22

Shaded surface Display (SSD) or Surface rendering

Question 23

Early systems, which contained only a single row of detectors in the z axis, obtained data for one slice with each rotation

Answer 23

Single Detector Row CT (SDCT)

Question 24

The number of x-ray photons detected per pixel in CT

Answer 24

Single to nose Ratio (SNR)

Question 25

The process requires a scan acquisition, needle placement, another scan acquisition, adjustment of the needle, another scan acquisition, and so forth until the needle is confirmed to be in the correct location

Answer 25

sequential CT

Question 26

Factors that can be controlled by the operator and affect the quality of the image produced (e.g. mA, scan time, slice thickness, FOV, reconstruction algorithm, and kVp)

Answer 26

Scan Parameters

Question 27

Electronic component of CT scanner that measures remnant radiation exiting the patient, converting the radiation to an analog signal proportionate to the radiation intensity measured

Answer 27

Detector assembly

Question 28

A brief, persistent flash of scintillation that must be taken into account and subtracted before image reconstruction

Answer 28

Afterglow

Question 29

The disadvantage of solid state detector over xenon gas detector

Answer 29

Afterglow

Question 30

Changes the digital signal from the computer memory back to an analog format so that the image can be displayed on the monitor

Answer 30

Digital to analog converters (DAC)

Question 31

Measured from the middle of the one detector to the middle of the neighboring detector

Answer 31

Detector spacing

Question 32

They result when wide slices are used as source images

Answer 32

Stair-step artifacts

Question 33

Instructions that tell the computer what to do and when to do it

Answer 33

Software

Question 34

Ability of the detector to capture transmitted photons and change them to electronic signals

Answer 34

Detector efficiency

Question 35

Artifacts that relate to the cone-shaped beam required for MDCT helical

Answer 35

Cone beam artifacts

Question 36

Method of acquiring slices in which one slice abuts the next

Answer 36

Continuous

Question 37

Ability of the system to differentiate between objects with similar densities

Answer 37

Contrast detectability or low contrast resolution

Question 38

Included in the detector array and help to calibrate data and reduce artifacts

Answer 38

Reference Detector

Question 39

Determines how the data are filtered in the reconstruction process

Answer 39

Reconstruction algorithm

Question 40

Table movement per rotation divided by the selected slice thickness of the detector

Answer 40

Detector pitch

Question 41

The section of data selected for display on the image

Answer 41

Display field of view (DFOV)

Question 42

Process of creating a digital image from raw data

Answer 42

Reconstruction

Question 43

Processing of using the same raw data to later generate a new image

Answer 43

Retrospective Reconstruction

Question 44

Output device that allows the information stored in computer memory to be displayed

Answer 44

Display Monitor