Brainscape's Knowledge GenomeTM

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


See full index

Ct Review > Physcics > Flashcards

Physcics Flashcards

1
Q

Window width

A

•allows the adjustment of gray scale

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

Window level

A

•sets the density of the image

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

Ct numbers are usually provided in the form of

A

•hounsfield units

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

First generation Ct scanners rotated in increments of

A

•180 degrees

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

Analog to digital converter

A

•responsible for transforming analog signal from the detectors into a digital form for the computer

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

Average hounsfield unit number for bone

A

•+1000

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

Eliminates the need for cables, allows for continues gantry rotation

A

•slip rings

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

Purpose of CT focal spot size

A

•influences spatial resolution

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

Artifact unique to multislice CT (MSCT)

A

•cone beam artifact

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

A 16-slice system is capable of acquiring ______ images

A
  • 16 images

* 16 slice possesses 16 data channels and is capable of acquiring 16 images per gantry rotation.

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

Threshold setting

A

•used to include/exclude info during 3D reconstruction of a Ct scan

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

Main controlling factor of Effective mAs

A
  • pitch the table speed is the main controlling factor

* effective mAs= mAs/pitch

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

X,Y,Z

A
  • X Sagittal plane
  • Y coronal plane
  • Z axial plane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How Ct tube creates X-rays

A
  • tube consist of a cathode and and anode

* electrons travel from cathode and strike the anode made of tungsten

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

When the tech manipulates the mA it changes what inside the tube

A

•changes the cathode filament temperature

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

The typical kVp for Ct

A

•120 kV

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

Reducing the tube rotation does what

A

•decreases pt radiation dose

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

Equation for determining the linear dimension of each pixel

A

•DFOV display field of view / matrix

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

The window setting levels for the brain should be displayed at

A
  • +50 HU

* the brain is soft tissue so should be displayed at about +50 HU

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

Back projection method of reconstruction major disadvantage

A

•star artifact

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

Pencil thin X-ray beam is associated with

A

•first generation CT scanners

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

A modern CT scanner possess a spatial resolution of up to

A

•25 lp/mm

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

High resolution comb

A

•acts as a grid removing unwanted scatter

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

Number of pixels used to display image

A

•matrix

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

Quality control

A

•corrective actions to improve performance

26
Q

Selecting a Small filament improves

A

•spatial resolution

27
Q

MSCT is capable of differentiating adjacent objects with attenuation differences as small as _______HU

A

•3HU

28
Q

Possible artifact from beam hardening

A

•polyenergetic X-ray beam artifact varying photon energy

29
Q

With MSCT what determines the width of the reconstructed section

A

•detector collimation

30
Q

HU value for a pixel whose attenuation is less than water would be considered

  • positive
  • high contrast
  • negative
  • low contrast
A

•negative

31
Q

DFOV

A
  • display field of view
  • controls the amount of scanned information to be displayed on the matrix
  • a small DFOV will magnify the CT image on the display monitor
32
Q

The bit depth of a digital imaging system defines the number of information bits contained with each

A

•pixel

33
Q

All modern MSCT systems typically employ what type of detectors

A
  • solid state scintillation

* accurately record X-ray energy from any angle

34
Q

Partial volume artifact is related to

A

•cupping

35
Q

3 factors that affect scatter

A
  • field size
  • part thickness
  • kVp
  • directly related as factors increase scatter increases
36
Q

Pixel

A
  • picture element composed of x and y axis

* 2D

37
Q

Air HU

A

•-1,000

38
Q

Bone HU

A

•1,000

39
Q

Blood HU

A

•40 HU

40
Q

CSF HU

A

•15 HU

41
Q

Fat HU

A

•-50 to -100 HU

42
Q

Slice thickness and spatial resolution relation

A
  • inversely related

* as slice thickness increases spatial resolution decreases.

43
Q

Beam shaping filter does what

A
  • hardens the beam

* removes low energy photons

44
Q

Pre pt collimator

A
  • Located just before X-ray hits the pt
  • controls field size on the pt
  • controls con beam
45
Q

Pre-detector collimator

A
  • located under pt after X-rays pass pt

* controls slice thickness at the detector array

46
Q

Matrix

A
  • made up of multiple pixels arranged in volume and rows

* as matrix number increases, image resolution increases

47
Q

Voxel represents

A
  • a volume of tissue

* 3D

48
Q

Compton scatter

A

•removal of an outer orbit election by X-ray photon

49
Q

Photoelectric effect

A
  • removal of an inner orbital electron by an interacting X-ray photon
  • outer shell fills in void
50
Q

Short wavelength and high frequency =

A

•high energy

51
Q

Long wavelength and low frequency =

A

•low energy

52
Q

Beam hardening

A

A streaking artifact commonly due to the beam changes in quality as it passes through different densities

53
Q

Inherent filtration of the CT X-ray aluminum tube housing

A

•1.2mm

54
Q

Dimensions of voxel

A

•calculated by pixel x section width

55
Q

Pre patient collimator

A
  • determines the range the z axis

* longitudinal collimation

56
Q

Post pt collimator

A
  • aka pre detector collimator
  • beam width
  • determines slice thickness
57
Q

Detector that contains narrow elemrs flanked by wider detectors is called

A

•hybrid array

58
Q

The two best factors resulting in equal lengths in all directions

A
  • section width thinnest detector collimation to produce thin slices
  • using the smallest DFOV
  • minimizing these two factors results in equal voxel all around
59
Q

Ring artifact typically caused by

A

•faulty detector

60
Q

Spatial resolution has the ability to

A

•image small objects

61
Q

The term ______ is used to describe each sample of ray sum measurement made by DAS data acquisition system

A

•view

62
Q

CTDI volume

A
  • CT dose index

* measures the radiation output from the CT scanner

Ct Review (8 decks)

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