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X-Ray Physics > XP Midterm > Flashcards

XP Midterm Flashcards

1
Q

What’s another term for SPATIAL QUALITY?

A

Geometric characteristics

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2
Q

What 3 factors must be correct to produce OPTIMUM CONTRAST?

A

Film type
Film processing
Exposure factors

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3
Q

Contrast is MEASURED and given a ____ value.

A

Numerical value

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4
Q

How is CONTRAST determined in FILM BASED IMAGING?

A

The difference between the OBJECT + BACKGROUND.

Ratio of brightness
“OBJECT : BACKGROUND”

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5
Q

How is CONTRAST determined in MAMMOGRAPHY?

A

A measured DENSITY LEVEL

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6
Q

DIGITAL IMAGE CONTRAST is obtained by

A

Proper digital processing

Adjustment of the display + window

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7
Q

What 2 compounds are used to ADD CONTRAST to low contrast objects in radiography?

A

Barium - high physical contrast
Iodine

*Good x-ray absorbers bc of ATOMIC # (size)

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8
Q

The source of MRI contrast is

A

Proton density
T1 LONGITUDINAL relaxation time
T2 TRANSVERSE relaxation time
Fluid movement

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9
Q

Do MRIs use x-rays?

A

Nope.

Uses the MAGNETIC field + radio frequency PULSES

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10
Q

NOISE ___ VISIBILITY of low contrast items.

A

Reduces

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11
Q

In NUCLEAR MEDICINE IMAGING, contrast depends on

A

Variation of radioactivity in a certain section of the body.

Differential uptake of the NUCLIDE + DISTRIBUTION …

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12
Q

What are associated with the differential uptake of the NUCLIDE + DISTRIBUTION?

A

the PHYSIOLOGICAL function

PATHOLOGICAL conditions.

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13
Q

ULTRASOUND PHYSICAL CONTRAST comes from

A

Echo made by differences in ACOUSTICAL IMPEDANCE of tissues

RBC movement

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14
Q

Define “Artifacts”

A

Objects that are NOT part of the patient, but are VISIBLE on the image

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15
Q

What is another term for “blur”?

A

Unsharpness

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16
Q

Projection imaging is ___ + ___

A

Radiography

Flouroscopy

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17
Q

Types of Tomographic Imaging

A 
Tomography
CT
MRI
PET
SPECT
Ultrasound

*produce slices

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18
Q

3D Imaging is COMPUTER BASED ___ + ___

A

CT

MRI

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19
Q

The amount of BLURRING is dependent upon

A

Blur characteristic of imaging modality

Selection of technique factors/protocol of procedure

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20
Q

____ CAMERA NUCLEAR MEDICINE produces the ____ NOISE.

A

Gamma Camera NM

Most noise

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21
Q

___ produces the LEAST NOISE.

A

Plain film radiography

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22
Q

Highest BLUR

A

Gamma camera nuclear medicine

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23
Q

Lowest BLUR

A

Mammography

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24
Q

Image noise + blur PRODUCE

A

“Curtain of invisibility”

“Window of invisibility”

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25
Q

Modalities with HIGH BLUR use ____ time to produce the image.

A

Longer

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26
Q

CT produces ___ or ___ of TISSUE information.

A

Voxels or

Cubes

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27
Q

The ability to detect an object generally INCREASES with

A

Background brightness

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28
Q

When VIEWER CONTRAST is LOW, what must the OBJECT have in order to be seen?

A

High SUBJECT contrast

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29
Q

Observer contrast sensitivity is effected by

A

Glare
Viewing distance
Object size
Background structure

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30
Q

MASKING extra light from around the IMAGE can

A

Improve visibility of DETAIL

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31
Q

Low contrast film (reduces/increases) NOISE?

A

Reduces

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32
Q

What is the main difference between DIGITAL and FILM RADIOGRAPHY?

A

Digital Imaging doesn’t have a DISTINCT or FIXED SENSITIVITY

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33
Q

What is “Image Integration” used for in FLUOROSCOPY?

A

To reduce noise

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34
Q

“Photon fluctuation” is dependent on

A

The photon concentration of exposure

35
Q

What are the MAJOR FACTORS that affect “Radiographic receptor sensitivity”

A

Film sensitivity
Screen CONVERSION efficiency
Screen ABSORPTION efficiency

36
Q

“Round Blur”

A

Intensifying screens of image intensifiers

37
Q

“Square Blur”

A

Digital imaging

*Includes CT

38
Q

“Elongation Blur”

A

Motion

39
Q

“Focal Spot Blur”

A

Various patterns

40
Q

What is the “Composite Modulation Transfer Function” used for?

A

To evaluate various components of an imaging system.

It’s a GRAPHICAL representation of the MODALITY BLUR.

41
Q

In order for ENERGY to be useful in imaging, what does it need to do?

A

Must be able to penetrate the body.

42
Q

What’s the relationship between ENERGY and WAVELENGTH?

A

They’re INVERSELY proportional

43
Q

When is the chance of PHOTON ABSORPTION greatly enhanced?

A

If it encounters matter with ELECTRON ENERGY close to that of the PHOTON.

44
Q

High energy ELECTROMAGNETIC RADIATION is measured in

A

Multiples of electron volts

45
Q

The “Radio frequency” portion of the SPECTRUM is measured in

A

Frequency

46
Q

What is a POSITRON needed for?

A

To annihilate an electron

47
Q

Electrical circuits must contain a ___ & ___ connected by CONDUCTORS.

A

Source

Load

48
Q

“Alternating current” in North America is

A

Cycles between POSITIVE and NEGATIVE flow

60 times per SECOND

49
Q

Direct current flows in how many directions?

A

One
Uno
Un

50
Q

1 coulomb = ___ mAs

A

1000

51
Q

What 3 types of energy can ELECTRONS possess?

A

Kinetic energy
Potential energy
Rest mass

52
Q

What is “Kinetic Energy”

A

Energy in motion

53
Q

The ELECTRON is the ___ unit of mass.

A

Smallest unit

54
Q

What’s the difference between the POTENTIAL ENERGY between 2 conductors?

A

The voltage

55
Q

The AMOUNT of energy TRANSFERRED depends upon what 3 things?

A

Voltage
Current
Duration of transfer

56
Q

Conventional “Roentgen R”

A

SI Units COULOMB/kg

57
Q

SI Unit Gray

A

Convention RAD

58
Q

SI Becquerel

A

Conventional Curie

**?

59
Q

SI Sievert

A

Conventional REM

60
Q

The “Surface Integral Exposure” (SIE) is another way of expressing

A

Total exposure to the body

61
Q

The possible STOCHASTIC RISKS of cancer relate more to ____ as opposed to Fluoroscopy.

A

The Surface Integral Exposure

62
Q

What is an alternate name for “Surface Integral Exposure”?

A

Exposure Area Product

63
Q

Why is the “R” or “Roentgen” still used?

A
  • It honors the physicist that discovered x-ray
  • The units are CONVENIENT for MEDICAL imagining
  • It’s the right SIZE for imaging techniques
64
Q

“Photoelectric Interactions” happen most often when?

Competition of Photons

A

Photon energy > Electron binding energy

Slightly more

65
Q

The probability of “Photoelectric Interactions” is dependent on what?

(Competition of Photons)

A

Atomic # of the material

66
Q

“Compton Interactions” occur most often with

Competition of Photons

A

Electrons with LOW binding energy

67
Q

What is the “Linear Energy Transfer”?

A

The rate at which ELECTRONS transfer energy

68
Q

What is “Filtration”?

A

The SELECTIVE ATTENUATION of the photons according to their energy BEFORE entering the patient

69
Q

In terms of “Forward Scatter Radiation”, the BEAM SIZE or AREA of EXPOSURE impacts what?

A

The AMOUNT of forward scatter

70
Q

In terms of “Forward Scatter Radiation”, the BODY SECTION THICKNESS ____ the SIZE of what?

A

Increases the SIZE of the

SOURCE of scatter

71
Q

In terms of “Forward Scatter Radiation”, scatter is MORE PENETRATING with (higher/lower) kVp.

A

Higher kVp

72
Q

In terms of “Forward Scatter Radiation”, HIGHER kVp scatter contributes more to what?

A

The RADIATION penetrating the body

73
Q

In terms of “Forward Scatter Radiation”, LOW kVp PHOTONS are absorbed/scatter at the ____ of the body and DOES NOT impact ____.

A

Surface of the body

Doesn’t impact FORWARD SCATTER

74
Q

Photoelectric interactions occur with ___ BOUND ATOMS.

A

Tightly bound atoms

75
Q

___ + ___ increase with INCREASED kVp.

A

Compton

Forward scatter radiation

76
Q

Better scatter penetration happens when kVp is (increased/decreased)?

A

Increased

77
Q

The average range of a group of PHOTONS is ____ related to the ATTENUATION RATE (filtration).

A

Inversely related

78
Q

(Increasing/decreasing) the rate of attenuation by CHANGING PHOTON ENERGY or TYPE OF MATERIAL (increases/decreases) the average photon range.

A

Increasing the rate of attenuation

Decreases average photon range

79
Q

The average photon range is EQUAL to

A

the “Reciprocal Attenuation Coefficient”

80
Q

Average Photon Range

A

1/A.C.

81
Q

“Beam Quality”

A

The beam’s ability to PENETRATE

Stop humping the laser.

82
Q

What 2 things make each imaging method unique?

A
  1. Tissue characteristics visible in image

2. Viewing perspective

83
Q

What 3 things do blur affect?

A

Anatomical detail
Sharpness of objects
Spatial resolution

X-Ray Physics (2 decks)

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