Computed Tomography Scan Parameters

Question 1

is a set of user selectable factors that determines the resultant CT image, the scan length, orientation, image size, thickness and increment, noise etc.

Answer 1

Scan parameters

Question 2

To change a specific scan parameter is also to change

Answer 2

the resultant images

Question 3

This is the position of the patient relative to the gantry and the patient couch

Answer 3

SUPINE
PRONE
LEFT OR RIGHT LATERAL DECUBITUS

Question 4

Where must the body part of interest be placed for CT scans

Answer 4

Isocenter

Question 5

Are specific points in the body that will determine the scan area

Answer 5

Anatomical landmarks in CT

Question 6

Anatomical landmark for Heat CT

Answer 6

glabella

Question 7

Anatomical landmark for Neck CT

Answer 7

thyroid cartilage

Question 8

Anatomical landmark for chest and neck CT

Answer 8

Sternal notch

Question 9

Anatomical landmark for Abdominal CT

Answer 9

Xiphoid Process

Question 10

the scanned projection radiograph, acquired by the CT system to allow the user to prescribe the start and end locations of the scan range

Answer 10

Scout image or the CT localizer radiograph

Question 11

These images are not cross-sectional in nature; rather they are very similar to images acquired with conventional radiographic projection techniques

Answer 11

Scout Image

Question 12

What does GE call scout imaging?

Answer 12

Scout

Question 13

What does Philips call scout imaging?

Answer 13

Surview

Question 14

What does Siemens call scout imaging?

Answer 14

Topogram

Question 15

What does Toshiba call scout imaging?

Answer 15

Scanogram

Question 16

What does Hitachi call scout imaging?

Answer 16

Scanogram

Question 17

Where is tube suspended during scout generation

Answer 17

above patient

Question 18

How is the tube positioned for Lat Scout?

Answer 18

90 degree angles to patient

Question 19

basically the length of the scan (hence the word scan length technologist sometimes refer to) measured in millimeters

Answer 19

Range

Question 20

This is planned on the scout image, also varies depending on the protocol selected and patient size

Answer 20

scan range

Question 21

Also called calibration field of view

Answer 21

Scan Field of View (SFOV)

Question 22

Diameter of the circular region within the scan plane over which projection data are collected

Answer 22

Scan Field of View

Question 23

It depends on the number of detectors activated to collect the data.

Answer 23

Scan Field of View

Question 24

How is scan field of view determined?

Answer 24

Number of detectors activated

Question 25

For best resolution, what is the best scan field of view size?

Answer 25

Smallest possible

Question 26

Directional coordinate systems have been called

Answer 26

RAS systems (Right-left, Anterior-posterior, Superior-inferior. )

Question 27

The body part included in the region of interest but outside the scan field of view will not have any data and not included in the scan

Answer 27

OUT OF FIELD artifact

Question 28

Determines how much raw data is used in displaying the acquired image

Answer 28

Display Field of View

Question 29

Display Field of View is also called

Answer 29

zoom or target

Question 30

Relationship of Display field of view with scan field of view

Answer 30

DFOV CAN BE EQUAL OR LESS OF SFOV

Question 31

Relationship of DFOV size and pixel, resolution and detail

Answer 31

Large DFOV, Large Pixels, = Low Spatial Resolution, Low visibility of detail

Question 32

Mode where the table stops at the scanning position and the tube rotates around the patient

Answer 32

Conventional/Axial/Regular Mode

Question 33

Patient continuously moving in the z-axis direction while the tube rotates around

Answer 33

Spiral/Helical

Question 34

Alternative name for reconstruction algorithms

Answer 34

Convolution kernels

Question 35

Various filters applied in filtered back projection reconstruction

Answer 35

Reconstruction Algorithm

Question 36

Various Types of Filter for soft tissue (abdomen , stonogram, muscles) Head – for the brain Bone – For osseous parts of the body Detail – for body parts that requires high spatial resolution (eg. Neck)

Answer 36

Standard

Question 37

Various Types of Filter for the brain Bone – For osseous parts of the body Detail – for body parts that requires high spatial resolution (eg. Neck)

Answer 37

Head

Question 38

Various Types of Filter for osseous parts of the body | Detail – for body parts that requires high spatial resolution (eg. Neck)

Answer 38

Bone

Question 39

Various Types of Filter for body parts that requires high spatial resolution (eg. Neck)

Answer 39

Detail

Question 40

Depending on the examination, the gantry housing can be tilted. This is mostly done in the axial scanning. The range of tilt depends on the position of the organs to be scan on the scout image

Answer 40

Gantry Angle

Question 41

What does lower kV do to the resultant CT image

Answer 41

Lower kV

Question 42

What happens to kV as it is lowered and how it affects noise?

Answer 42

Lower kV=more noise