Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CT Scan > Axial VS Helical Scanning > Flashcards

Axial VS Helical Scanning Flashcards

1
Q

Scanning mode where the table stops at the scanning position and the tube rotates around the patient?

A

Conventional / Axial / Regular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Scanning mode where the patient is continuously moving in the z-axis direction while the tube rotates around?

A

Spiral / Helical Mode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Earliest scanning mode?

A

Step-and-shoot method

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Alternative name for Step-and-shoot scanning?

A

Axial Scanning
Conventional / Regular Scanning
Serial Scanning
Sequence Scanning

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

CT table moves to the desired location and remains stationary while the x-ray tube rotates within the gantry, collecting data

A

STEP-AND-SHOOT SCANNING

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Axial slices lie ___ to one another

A

parallel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The slice beginning matches

A

exactly the slice end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Perfect circles are formed that are ____ to z axis

A

perpendicular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Used by both third- and fourth-generation scanners

A

STEP-AND-SHOOT SCANNING

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

obtained data for one slice with each rotation (for early systems)

A

STEP-AND-SHOOT SCANNING

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How many degrees rotation did the third generation systems use for each acquisition for step and shoot scanning?

A

360 degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How many degrees rotation did the fourth generation systems use for each acquisition for step and shoot scanning?

A

400 degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

In all types of scanners using this method there is a slight pause in scanning between data acquisitions as the table moves to the next location. , referred to as the

A

interscan delay

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In early scanners the time for a complete cycle allowed only a single scan to be acquired

A

each time the patient held her breath.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Newer scanners shortened the cycle time dramatically, allowing axial scans to be

A

“clustered”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Grouping scans in clusters reduces what problem

A

Slice misregistration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Advantages of axial scanning mode?

A

Highest Image quality, superior to helical methods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why does step-and-shoot methods produces highest image quality

A

axial nature and the fact that the patient table remains stationary during data acquisition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Disadvantages of axial scanning?

A 
Adds to the total examination time
Less than 30 seconds
Not useful in contrast studies
Breathing creates motion artifact
Data reconstruction and reformation limited
Induce motion in patients organs
Misregistration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Delay inherent in axial scan sequences which is caused by the differences in patients breathes with each data acquisition?

A

Misregistration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

When was helical scanning introduced?

A

late 1980s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Alternative name for helical scanning?

A

Spiral or Continuous acquisition Scanning

23
Q

What did helical scanning eliminate?

A

Interscan delay

24
Q

three basic ingredients that define a helical scan process

A
  1. a continually rotating x-ray tube,
  2. constant x-ray output, and
  3. uninterrupted table movement.
25
Q

Helical scanning is often referred to as

A

volumetric scanning

26
Q

Refers to the fact that the end result of such a scanning method is a block of data, not separate slices, as occurs in traditional axial scanning?

A

Volumetric scanning

27
Q

Increasing the scan speed results in improved image resolution owing to the ability to obtain images with:

A

Improved iodinated contrast concentration.
Decreased respiratory and cardiac motion artifact.
Superior multiplanar and three-dimensional (3-D) reformation capabilities.

28
Q

Other advantages of helical scanning

A

Improving diagnostic accuracy.
Patient comfort.
Department productivity.

29
Q

What major improvements lead to the development of the helical scan?

A 
Slip ring design
More Efficient Tube cooling
Higher x-ray output
More efficient detectors
Smoother table movements
Software improvements for table motion
Improved raw data management
30
Q

allow the tube to move continually in the same direction

A

Newer systems slip rings

31
Q

eliminates cumbersome electrical cables and makes possible a data-gathering system using a continuous rotation of the x-ray source

A

Slip ring technology

32
Q

There is constant x-ray output throughout a helical scan acquisition that Can last more than 60 seconds without a pause for cooling.

A

More-Efficient Tube Cooling

33
Q

The tube makes a complete rotation in 1 second or less.

Overal decrease in mAs to one third (or less) compared to axial scan if the mA remained the same.

A

Higher X-ray Output

34
Q

allow the total radiation dose to be lower for both helical and axial scans done on the newer systems.

A

more-efficient detectors

35
Q

Motion artifact degrades images, and images are created while the table is in motion, helical scanning requires the table to move very smoothly.

A

Smoother Table Movement

36
Q

Manufacturers then since have created special software that adjusts for the smooth table motion

A

Special Software

37
Q

take the slant and blur out of are statistical methods that create images that closely resemble those acquired in a traditional axial mode

A

Interpolation

38
Q

Two most common schemes in interpolation

A

360° and the 180° linear interpolations (abbreviated 360LI and 180LI)

39
Q

Huge amounts of data are generated in a very short time

A

Improved Raw Data Management

40
Q

a parameter that is commonly used to describe the CT table movement

A

Pitch

41
Q

It is most commonly defined as the travel distance of the CT scan table per 360° rotation of the x-ray tube, divided by the x-ray beam collimation width

A

Pitch

42
Q

When the table feed and beam collimation are identical how much is the pitch?

A

1

43
Q

When the table feed is less than the beam collimation, pitch is?

A

Less than 1 and scan overlaps occur

44
Q

To maintain a pitch of 1, the table speed will vary according to

A

the slice thickness selected

45
Q

describes the relationship of the table speed to the slice thickness

A

Pitch

46
Q

As the pitch increases, so does the

A

slice angle

47
Q

is required to straighten the image and the effects of interpolation become more pronounced

A

More interpolation

48
Q

More interpolation effects to

A

image unsharpness and effective slice thickness blooming

49
Q

Increasing the pitch will result to

A
  • a scan covering more anatomy lengthwise for a given total acquisition time
  • reduce the radiation dose to the patient
50
Q

A decrease in pitch will

A

slows down the table speed

51
Q

will result in overlapping slices and will decrease the amount of anatomy covered per unit time and increase the radiation dose to the patient

A

A pitch of less than 1

52
Q

A pitch that is not commonly used

A

pitch of less than 1

53
Q

A compromise is necessary when the pitch is

A

extended beyond 1

54
Q

exchange for the shortened examination time and the reduced patient radiation dose comes

A

comes the loss of image sharpness and a decrease in the SSP

CT Scan (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions