Brainscape's Knowledge GenomeTM

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


See full index

CT Registry > Image Production > Flashcards

Image Production Flashcards

1
Q

Focal spot size range

A

0.5 and 1.2 mm

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

mA range

A

30 - 800 mA

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

Photon fluence

A

Quantity of x-ray photons passing through a specified area (mAs value directly controls photon fluence)

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

Photon flux

A

The rate at which a quantity of x-ray photons (fluence) passes though a unit area over a unit of time

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

Effective mAs

A

Calculated mAs per acquired slice with a MSCT system

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

Effective mAs formula

A

mAs / pitch

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

kVp range

A

70 - 150 kVp

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

Beam pitch formula

A

table feed per rotation / total collimation

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

Crystal materials

A
  • Cesium iodide
  • Cadmium tungstate
  • Ceramic gadolinium
  • Oxysulfide
  • Scintillating gemstone
  • Bismuth germanate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

First generation

A
  • Pencil beam
  • Two detectors
  • Translate (1 degree) and rotate (rectilinear or translate-rotate scanning)
  • Head imaging only
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Second generation

A
  • Fan beam
  • Increase in number of detectors
  • Greater increments of rotation
  • Translate and rotate (rectilinear or translate-rotate scanning)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Third generation

A
  • Fan beam
  • Expanded curvilinear array of detectors rotates with tube
  • Rotate-rotate geometry
  • Rotate only
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Fourth generation

A
  • Fan beam
  • Stationary circular detector array
  • Rotate-stationary geometry
  • Only tube rotates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Linear attenuation coefficient

A

Value assigned to ability of an object to attenuate x-ray beam

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

Examples for cone beam reconstruction algorithms (Used to overcome beam divergence)

A
  • Feldkamp-Davis-Kress (FDK)

- Advanced single-slice rebinning (ASSR)

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

CT number formula

A

((ut - uw)/uw) x K

K - contrast factor, 1000

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

HU Dense bone

A

3000

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

HU Muscle

A

50

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

HU White matter

A

45

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

HU Gray matter

A

40

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

HU Blood

A

45

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

HU CSF

A

15

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

HU Water

A

0

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

HU Fat

A

-100

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

HU Lungs

A

-200

26
Q

HU Air

A

-1000

27
Q

Max number of pixel CT numbers

A

2^k

k is bit number

28
Q

Method of externally viewing a 3-D reconstructed object

A

Orthographic volume rendering

29
Q

Viewpoint of being within the lumen of the object

A

Perspective volume rendering (also referred to as immersive rendering)

30
Q

3 general types of noise

A
  • Quantum noise
  • Electronic system noise
  • Artifactual noise
31
Q

2 main types of digital image compression

A
  • Lossless (reversible) compression

- Lossy (irreversible) compression

32
Q

The average energy of photons in the x-ray beam is represented in units of:

A

kilo-electron volts (keV)

33
Q

kVp also known as:

A

Potential difference

34
Q

Intensity also known as:

A

Quantity

35
Q

Energy also know as:

A

Quality or hardness

36
Q

Contrast resolution also known as:

A

Low-contrast detectability or sensitivity of the system

37
Q

What is the most important factor influencing contrast resolution in CT?

A

Image noise

38
Q

Aliasing is cause by:

A

Under-sampling

39
Q

Rotation time

A

0.2 - 1 sec

40
Q

Gantry includes

A
  • X-ray tube
  • Detectors (detector array)
  • Collimators
  • High-voltage generator
  • ADC
  • DAS
  • Slip ring
41
Q

Angle of the tube and detectors in relationship to the patient position during scout acquisition

A

Azimuth

42
Q

Overranging or z-axis overscanning

A

Applying radiation dose before and after the acquisition volume to ensure sufficient data collection for the interpolation algorithms of helical CT reconstruction

43
Q

Isotropic

A

Voxels with equal dimensions along the x-, y-, and z-axes

44
Q

CT system’s response to a spatial frequency

A

Modulation transfer function (MTF)

45
Q

In-plane spatial resolution of modern MDCT system can reach levels of:

A

25 lp/cm or more

Able to resolve objects smaller than 1 mm

46
Q

MDCT systems are capable of differentiating adjacent objects with attenuation differences as small as:

A

3 HU

47
Q

Spatial resolution is improved by:

A
  • Small focal spot size
  • Small detector size
  • Edge enhancing reconstruction algorithm (bone or lung)
  • Small DFOV
  • Large matrix size
  • High sampling frequency
  • Thinnest beam collimation (acquisition slice thickness)
  • Decreased pitch
  • Reconstruct with thinnest detector collimation
  • Increased rotation time
  • Thinnest acquisition and reconstruction slice thickness
48
Q

Contrast resolution is improved by:

A
  • Use of contrast to augment inherent subject contrast
  • Smaller part
  • Increased technical factors
  • *Thin beam collimation (to reduce scatter)
  • Soft tissue reconstruction algorithm
  • Narrow WW
  • Thicker detector collimation (to reduce noise due to decrease in photon flux in decreased section width)
  • Decrease noise
  • Thicker acquisition and reconstruction slice thickness
49
Q

Noise is improved by:

A
  • Increase photon flux (increase technical factors)
  • Increase voxel dimension (but risk partial volume effect)
  • Decrease pitch
  • Better detector sensitivity and efficiency
  • Smaller part (or utilize ATCM)
  • Soft tissue reconstruction algorithm
50
Q

Temporal resolution is improved by:

A
  • Decrease rotation time
  • Increase acquisition slice thickness
  • Increase pitch
  • Segmenting data acquisition process
  • Physiologic gating
51
Q

Nyquist theorem

A

Data sampling frequency must be at least twice the object’s spatial frequency in order for the object to be resolved by the CT system (related to spatial frequency)

52
Q

SSP, PSF, FWHM

A

Longitudinal spatial resolution

53
Q

MTF

A

In-plane spatial resolution

54
Q

Average photon energy of primary beam used in CT

A

Approximately 70 keV

55
Q

Analytic methods of CT image reconstructions include:

A

Filtered back-projection and Fourier transform method

56
Q

Linear attenuation coefficient of water

A

0.206

57
Q

Effective section width is at:

A

FWHM of the SSP

58
Q

Io

A

Incident intensity

59
Q

I

A

Transmitted intensity (intensity of radiation passing through the tissue )

60
Q

A form of parallel processing used by a computer to improve computation speed

A

Pipelining

61
Q

CT system power output

A

60-100 kW

CT Registry (4 decks)

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