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CT Scan > Module 1 > Flashcards

Module 1 Flashcards

1
Q

Allows the superimposition structure to be lurred and thus leaving the area of interest in maximum focus.

A

Axial tomography

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2
Q

Axial tomography is also called

A

Conventional tomography

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3
Q

2 types of axial tomography

A

sagittal and coronal

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4
Q

hounsfield unit also reffered to as

A

ct number

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5
Q

Goals of CT:

A

Overcome superimposition if structures
Improve image contrast
Measure small differences in tissue contrast

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6
Q

1st mathematically principle developed
It is possible to build up an image of two or three dimensional object from a large number of projections from different directions.

A

1917 by J. Radon

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7
Q

cross section portion of body scanned is called

A

slice/ cut

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8
Q

two dimensional array of numbers arranged in rows and columns is called

A

Matrix

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9
Q

Each square in matrix is called

A

Pixel or picture element

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10
Q

3D
represents tiny block of tissue called

A

voxel

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11
Q

numbers in the image matrix is called

A

ct number or hounsfield unit

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12
Q

restricts xray beam to specific area
controls slice thickness
reduce pt dose
improve image quality

A

Functions of Collimator

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13
Q

Advantage of this CT detector is to remain stable under pressure, cheaper, and easier to calibrate.
Can be used in third gen scanner.
60 - 87% absorption

A

Xenon gas detector

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14
Q

This gas must be kept under pressure in an aluminum casing

A

Xenon gas

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15
Q

Advantage of this CT detector is it has a high coefficient of 100%

A

Solid state crystal (Scintillation Detectors)

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16
Q

determines the radiation dose profile & pt radiation dose

A

Prepatient Collimator

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17
Q

determines the sensitivity profile & improves contrast

A

Postpatient/ Predetector Collimator

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18
Q

captures radiation beam from the patient & converts it into electrixal signals then be converted into binary information

A

CT Detector

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19
Q

Causes of ring artifacts

A

single detector
multiple detector
malfunction

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20
Q

The smaller the pixel size, the better the:

A

spatial resolution

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21
Q

Factors affecting Noise:

A

kVp & Filtration
Pixel size
Slice thickness
Detector efficiency
Pt dose

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22
Q

describes the amount of the CT number of a material is exactly proportional to the density of this material
must be calibrated frequently so that water is consistently represented by CT number 0

A

Linearity

23
Q

EMI Mark 1

A

1st Generation Scanner

24
Q

T/F
5th generation scanner uses translate-rotate principle

A

F
1st & 2nd generation

25
Q

for head ct scan only because abdomen or chest has motion

A

1st Generation

26
Q

more throughput, more information can be scanned
20 second image acquisition
able to rotate at 6°

A

2nd Generation

27
Q

complete rotation of XRT and detectors
scan time about .5 seconds or less

A

3rd Generation

28
Q

complete rotation of XRT around stationary detectors ring
fan beam geometry

A

4th Generation

29
Q

no XRT
uses electron gun
EBCT & DSR

A

5th Generation

30
Q

DSCT Scanner
Image moving structures such as heart
Minimize motion artifacts
Have multiple XRT and detectors

A

6th Generation

31
Q

number of line pairs per unit length is called

A

spatial frequency

32
Q

1 bar & its interspace of equal width

A

line pair

33
Q

Factors affecting Image Quality

A

Spatial resolution
Contrast resolution
Temporal resolution
Noise

34
Q

degree of blur or the ability to see the difference between two objects that are close together

A

Spatial resolution

35
Q

ability to differentiate between small differences in density within the image

A

contrast resolution

36
Q

Factors that improve Temporal resolution

A

Multidetector
Tube/Gantry rotation time
Dual source CT

37
Q

good for cardiac CT
freeze any motion of a scanned object

A

Temporal resolution

38
Q

scan parameters affecting contrast

A

slice thickness
reconstruction algorithm
image display (window width)

39
Q

scan parameters affecting spatial

A

SFOV
DFOV
Matrix
Reconstruction slice thickness
Detector aperture width
Slice thickness

40
Q

made of carbon filter
strong, rigid
doesn’t absorbs xrays coming from pt

A

patient couch/table

41
Q

quick heat transfer but heavy

A

all metal disk design

42
Q

base body is graphite
high heat storage capacity and faster anode cooling

A

brazed graphite anode disk

43
Q

can accommodate large, lightweight disks with large heat storage capacity and fast cooling rates

A

chemical vapor deposition graphite disk

44
Q

removes long wavelengths xrays
shapes the energy distribution across the radiation beam by using shaped filter

A

Filtration

45
Q

residual gas molecules present within the evacuated envelope

A

tube arcing

46
Q

topography

A

Allesandro Volta

47
Q

made many advances in rotational scanning

A

David E. Kuhl & Roy Q. Edwards

48
Q

derived a mathematical theory for image reconstruction
he also applied reconstruction technique in NucMed

A

Allan Mcleod Cormack

49
Q

inventor of clinical Computed tomography

A

Godfrey Hounsfiled 1967

50
Q

obtained readings from a specimen of Human brain

A

James Ambrose 1971

51
Q

1st whole body ct scanner

A

Robert Ledley 1974

52
Q

Major limitation of Radiography

A

Superimposition of anatomical structure
Radiography is qualitative rather than quantitative

53
Q

reduction of energy of xrays

A

attenuation

CT Scan (2 decks)

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