Brainscape's Knowledge GenomeTM

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


See full index

Ct Review Class > Ch.2 Ct Image Formation > Flashcards

Ch.2 Ct Image Formation Flashcards

1
Q

Digital images are?

P 4

A

Numerical representations of an object that can be recognized and processed by a computer

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

First step generating digital image of an object?

P 4

A

Divide the object into a grid of small regions

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

Pixel

A

Picture element that’s each small region of a grid

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

Rows and columns allows us to ?

P 4

A

Associate the location of specific structure within the object being imaged with specific pixel or group of pixels

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

Matrix

P 4

A

Grid of pixels

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

2nd step generating image

A

Sample the object in order to differentiate structures within the object and assign various shades of gray to the pixels representing the structure

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

X-ray photons that pass thru the body are measure by ______and converted into ______?

P 6

A

Detectors

Electric signals

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

Integer

P 6

A

Posit e or negative whole numbe

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

Value of integer determined by?

P 6

A

Signals strength

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

Display hardware

A

Assigns specific gray level to region of Ct image from which attenuation information was detected

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

Projection

A

View of anatomical cross section from particular vantage point

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

Ct scanning methods

P 8

A

Localizer
Conventional
Helical

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

Localizer scan

P 9

A

Obtained with stationary X-ray tube and patient table in motion

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

Why localizer scan ?

P 9

A

Aligns cross sectional slices with specific anatomical structures

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

Views used with localizer?

A

Ap
Lateral
Oblique

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

Length of anatomical coverage with localizer depends on?

P 9

A

Speed of table

Amount time X-ray is on

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

Ct localizer scan the anatomical structure appears? P 10

A

Superimposed

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

Ap localizer image used? P 10

A

Planning to specify perfectly transverse slices

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

Lateral localizer is used? P 10

A

Intend to angle gantry to specific oblique slices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which ct yields the best quality image free of helical artifacts?

P12

A

Conventional ct

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

Conventional ct used today?

12

A

Neurological studies involving temporal bones

Obese patients

Cardiac calcium scoring

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

Conventional ct the tube rotates around the patient while the table?

A

Stationary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Raw data

P 13

A

Data measured at each projection placed in computer file

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Single row detector

A

P 13

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

When performing a conventional scan , raw data from ____ cross sectional slice location is collected during a single rotation of the gantry?
P 13

A

One

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Multi row detectors

A

P14

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

When performing a conventional scan of multi row detector scanner , the raw data is from ______ cross sectional slice locations collected during a single rotation of the gantry

A

Several

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Raw data sample formula

A

Rows of detectors x # of detectors X projections required

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Helical scan

P 16

A

X-rays beam spiral or corkscrew paths around patients body as the table advances through the gantry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Most commonly used ct today?

A

Helical scan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Several advantages of helical ct

P 16-17

A 
Faster studies
More coverage in breath hold
No missed anatomy 
Less contrast agent needed
Arbitrary slice positioning 
Ideal data for post processing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Disadvantage of helicL scan?

P18

A

Artifacts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Helical path single row detector scanner in which thickness of X-ray beam _______ the thickness of the final slice

A

Equals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

The helical path on multi row detector scanner in which thickness of X-ray beam is ________ over four rows of detectors

A

Divided

35
Q

Interpolation

A

Mathematical problem in helical ct that changes helical data into raw data reconstructing it into final images

36
Q

Most ct aytms today use reconstruction method called ?

P 21

A

Filter back projection

37
Q

Two steps of filtered back projection?

P 21

A

Applying filter to raw data and back projection

38
Q

Back projection p21

A

Calculation used for reconstructing final images from raw data by adding together the attenuation information collected from all projections

39
Q

Through back,projection _______profiles are added together p 22

A

Attenuation profiles

40
Q

Convolution p 23

A

Reconstruction filter is Applied to raw data during image reconstruction

41
Q

Kernel p 23

A

Reconstruction filter

42
Q

Two reconstruction filters? P 23

A

Sharp

Smooth

43
Q

Sharp filter p 23

A

Improves definition of the edges of structures but doesn’t minimize grainy or speckled appearance of image

44
Q

Smooth filter p 23

A

Minimizes grainy appearance of noise in image so that the contrast between tissues can be better distinguished but does not improve edge definition

45
Q

Sharp reconstruction filter are often us for ? P 24

A

Musculoskeletal detail ( high contrast area)

46
Q

Smooth reconstruction filters are often used for ? P 24

A

Low contrast areas such as abdomen and brain

47
Q

If back projection was applied to raw data without convolution , what happens to tissues? P 24

A

Image would have blurry edges and they be more difficult to differentiate

48
Q

Iterative reconstruction p 25

A

Cycle of correction calculations which maybe applied during image reconstruction to reduce image noise and which allows greatly reduced dose to be used without compromising image quality

49
Q

Noise

A

Grainy appearance on image

50
Q

Important clinical significance of iterative reconstruction ? P 26

A

Significant less radiation dose while maintaining optimal image quality

51
Q

Cone beam artifact p 27

A

spreading of photons long patient table results in spoke or star like appearance

52
Q

Cone beam reconstruction p 28

A

Reconstruction algorithm designed for multi row scanner to collect more than four slices in a single rotation

53
Q

Back projection is used on ______row detectors and on multi row detectors that collect no more than _____slices in one rotation . Cone beam reconstruction applied to all other mdct scanners.
P 28

A

Single

Four

54
Q

When ct image is reconstructed it viewed on? P 29

A

Operators console

55
Q

Raw data is obtained on raw data device on?

A

Host computer

56
Q

Retrospective reconstruction p 29

A

Requires raw data, which is lost once that portion of raw data storage device is overwritten

57
Q

On mdct scanner, a retrospective reconstruction is common,y used to modify reconstructed ? P 30

A

Slice thickness

58
Q

Most Ct images are acquired in which orientation? P 31

A

Transverse

59
Q

Multiplanar reconstruction p 31

A

Allows Reconstruction of images in planes that would be difficult or impossible to acquire

60
Q

Multiplanar reconstruction requires ____ data ? P 31

A

Image data

61
Q

Steps of multiplanar reconstruction? P 31

A
  1. Region interest scanned to obtain transverse slices using helical imaging
  2. Raw data reconstructed using filtered back projection or cone beam reconstruction and transverse imaging viewed on operators console
  3. Multiplanar reconstruction initiated
  4. Stacks transverse images on top each other generate volume anatomical imaging
  5. Line places across stack transverse imaging indicating location of new image
62
Q

Why curved cut line allowed on multiplanar reconstruction? P 32

A

Enables tracing curved structure such as vessel so that structure is displayed in cross section

63
Q

Contiguous p 33

A

Slices with no gaps

64
Q

Why must images be contiguous in multiplanar reconstruction p33

A

No gaps in images

65
Q

Which type images best used for post processing techniques? P 33

A

Helical

66
Q

3D shaded surface display p 34

A

Reconstructs images of the surfaces of the anatomical structure

67
Q

3d SSD program process ? P 34

A

Stacks transverse slices to form a volume of anatomical data which must be contiguous

Dependent of determining difference of tissues being scanned through a threshold

68
Q

In 3d SSD , types of tissues are separated by ______ settings?
P 34

A

Threshold settings

69
Q

What is threshold value set to during 3d SSD? P 34

A

Equal to ct number of tissue on which we want to surface rendering

70
Q

Volume rendering p 35

A

Incorporates information from entire image data set , rather from the surface into processed image enabling visualization of structures above and below the surface

71
Q

Voxels in volume rendering p 35

A

Each voxel assigned opacity value as function of its density

72
Q

Each pixel in volume rendering p 35

A

Represents the sum of the contributions of each voxel along a ray passed through image data set

73
Q

Maximum intensity projection p37

A

Generated from transverse slices of a cta study by projecting the brightest pixels onto a plane

74
Q

Angiography p 37

A

Used to evaluate the vessels and is acquired with helical scan and timed iodinated contrast

75
Q

Most accurate mip results are obtained when ? P 38

A

Small volume of interest is selected

76
Q

Volume of interest p 38

A

In mip, affect way vessels appear

77
Q

Volume of interest increased? P 38

A

Additional anatomical structures and noise are included in the data upon which the mip algorithmn is applied - apparent vessel diameter of the mip image may decrease

78
Q

Ct images are filmed or transferred to ____ or ____? P 40

A

Viewing station or pacs

79
Q

Ct uses _____ film? P 40

A

Single emulsion

80
Q

Window adjustments allow,us? P 40

A

High resolution detail or soft tissue contrast by varying brightness and contrast settings

81
Q

Most ct systems today use a _______ camera ? P 40

A

Laser

82
Q

Laser camera expose the image displayed on monitor directly onto _____ with a laser p 40

A

Film

83
Q

Benefits of laser camera p 40

A

Less scattered light

Superior contrast

Ct Review Class (7 decks)

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