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Radiographic Technique I > Final > Flashcards

Final Flashcards

0
Q

What type of imaging has multiple source/detector arrays that make complete 360 degree rotations around the patient in the axial plane?

A

Modern CT scanners

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1
Q

What did Hounsfield and Mcleod invent in 1973?

A

CT

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2
Q

What makes the 2 dimensional image seen on axial data of the CT scanner?

A

Small Pixels

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3
Q

What unit is the reference for the depth of the CT slice (volume element)?

A

Voxel

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4
Q

The CT scanners can reformatt the image to sagittall, coronal, or 3D orientations. What is this referred as?

A

MPR = Multi Planar Reformatting

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5
Q

What’s the best quality visual image/orientation for the CT?

A

Axial (pixel)

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6
Q

What CT image (besides axial) can create a good quality image?

A

Isotropic Voxel

has the same depth, width, & height

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7
Q

What type of unit is used to describe the shade of grey that a tissue presents on the scan?

A

Hounsfield

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8
Q

What HU = 0?

A

Water

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9
Q

What HU = -1000?

A

Air

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10
Q

What HU = +400

A

Cancellous Bone

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11
Q

What HU = +700-2000

A

Cortical bone

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12
Q

What HU = +2500-3000

A

Metal

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13
Q

What is it called when emphasizing views of certain ranges in the HU scale (CT scan)?

A

Windowing

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14
Q

What tissue is at the low end of the HU scale?

A

Soft Tissue

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15
Q

What is emphasized at the higher value end of the HU scale?

A

Cortical and Medullary Bone

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16
Q

What do you call the part of the CT detector that cannot distinguish between different tissues?

A

Partial Volume Effect

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17
Q

What is the most common mechanical artifact in the CT scan?

A

Ring Artifact

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18
Q

What are 2 types of CT images that requires use of the 3D reformatting capacity of the scanner?

A

CT Colongraphy and Angiography

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19
Q

What’s the first step to creating an MRI image?

A

Strong magnetic field aligns the vector of spin of protons in the body

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20
Q

The strong magnetic field units range is ________.

A

0.3-3.0 Tesla

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21
Q

What “resonates” with the bodies protons, causing them to gain energy and precess (spin around their axis) at a higher energy?

A

A 2nd Radiofrequency

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22
Q

What happens when the 2nd radiofrequency is turned off?

A

The excess energy is emitted from each tissue according to its proton concentration

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23
Q

What characteristic of the tissue causes an MRI image?

A

Each tissue in the body has it’s own pattern of proton return to normal state

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24
Q

When the radiofrequency is turned off the proton energy is emitted from each tissue and converted into?

A

a visible image

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25
Q

Fat is the brightest in a T1 weighted image, therefore what are 3 examples of tissue signals (high vs. low signals)?

A
  1. Cord higher signal than CSF
  2. Medullary bone & Spinal cord are higher signal
  3. Water and cortical bone are lower signal
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26
Q

Water and edema have the brightest (high) signal in T2 weighted MRI images; therefore, what tissues will have high and what will have low signals?

A
  1. Nucleus pulposus and CSF is high

2. Medullary bone, spinal cord is low

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27
Q

What tissue is a low (dark) signal in both T1 & T2 MRI’s?

A

Cortical Bone

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28
Q

Does T1 or T2 have a better detailed image?

A

T1

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29
Q

What MRI system suppresses fat so that edematous tissue can be better evaluated?

A

STIR (Short Tau Inversion Recovery)

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30
Q

How do MRI differentiate structures (oppposed to density as used with the CT)?

A

High signal = bright
Low signal = dark
Intermediate = anywhere in between

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31
Q

Is it okay to have batteries or iron on/in a patient who needs an MRI?

A

NO

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32
Q

It’s important to be very still while taking a MRI; therefore, what type of patient cannot have a MRI?

A

Epileptic (Seizures), Reactive-PTSD

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33
Q

What are 4 MRI contraindications to implants of the cardiovascular system?

A
  1. Pacemaker
  2. Cardiac defibrillator
  3. Aneurysm clips
  4. Carotid artery vascular clamp
34
Q

What are 6 random contraindications for MRI’s?

A
  1. Neurostimulator
  2. Insulin or infusion pump
  3. Implanted drug infusion devise
  4. Bone growth/fusion stimulator
  5. Cochlear, otologic, or ear implant
  6. Some Tatoos (high metallic content)
35
Q

What imaging system uses x-rays?

A

CT

36
Q

MRI uses what for visual imaging?

A

Radiofrequency and magnets

37
Q

What imaging machine uses densities in tissues vs. signal intensity?

A

MRI - signal intensity

CT - densities

38
Q

Does CT or MRI provide exemplary detail?

A

CT

39
Q

What machine provides exemlary tissue differentiation?

A

MRI

40
Q

What machine can be reformatted from axial data?

A

CT

41
Q

What machine requires multiplanar image acquisition?

A

MRI

42
Q

What machine is the fastest?

A

CT (MRI not so fast)

43
Q

Can any machine take images on patients with metal or battery implants?

A

Yes, CT

44
Q

What machine is best for unstable patients?

A

CT

45
Q

What are other names for radionuclide imaging?

A

Scintigraphy and Bone scan

46
Q

What do patients ingest or get injected for Scintigraphy?

A

Radioisotopes chelated to substances that are inert

47
Q

What is the most common radioisotope used in bone scans?

A

Technetium 99

48
Q

Technetium 99 is referred to as a _______ that acts characteristically in the body and will circulate to areas of high physiologic function.

A

Tracer

49
Q

How can a Scintingraphy be useful (what does it identify)?

A

Areas of abnormally high or low metabolic activity in organs and bones

50
Q

What are 3 types of scintigraphy?

A
  1. 2D
  2. SPECT (single photon emission tomography)
  3. Hybrid SPECT
51
Q

What are “Hot Spots” in scintigraphy?

A

Areas of high metabolic activity

52
Q

What are “cold spots” in scintigraphy?

A

Area lacking vascular supply (abcess or avascular necrosis)

53
Q

What is unique about Hybrid SPECT?

A

It combines CT or MRI with scintigraphy to gain anatomic and physiological comparison

54
Q

What are the 3 types of bone scans?

A

Whole body, Limited, Three-phase

55
Q

What bone scan is used for systemic bone disorders (ie. metastasis, arthritis, etc.)?

A

Whole body (images the entire skeleton)

56
Q

What bone scan is used for fractures (occult/stress)?

A

Limited (images a specific region)

57
Q

What bone scan images flow, blood pool, delayed images and is used for infection (osteomyelitis vs. cellulitis)?

A

Three Phase

58
Q

What patient population benefits from the 3-phase bone scan for detecting early infection?

A

diabetic patients

59
Q

How much Technetium 99m-MDP has an effective dose of 3 mSv whole body?

A

20 mCi

60
Q

What’s the half life, biological half life, and effective half life for Technetium-99m-MDP?

A

6 hour half life
24 hour biological half life
4.8 hour effective half life

61
Q

Describe the effective half life of Technetium-99m-MDP?

A

It’s total half life is 6 hours; however, the isotope is decaying & the body has started to clear it throught the urinary system.

62
Q

Are bone scans sensitive or specific for increased bone metabolism?

A

Highly sensitive (poorly specific)

63
Q

What imaging uses sound waves to bounce of internal structures?

A

Ultrasonography

64
Q

What information bounces off the internal structures that allows an image to be seen?

A

Echos

65
Q

What causes the sound waves to “bounce back” to the ultrasound transducer?

A

Changes in tissue density (solid vs. cysts)

66
Q

When using an Ultrasonography where is the Transducer placed?

A

On the skin over the area of interest

67
Q

What’s placed between the skin and the Transducer in order to facilitate sound wave transmission from Transducer?

A

Ultrasonic gel

68
Q

What is unique about Ultrasonography?

A

It’s a real time study (structures viewed under active or passive motion) and can orient the image that’s not orthogonal

69
Q

Ultrasonography is dynamic and image quality is highly dependent on what/whom?

A

The technician

70
Q

Does US use ionizing radiation?

A

NO

71
Q

What are the strengths of US?

A
  • Obstetric evals
  • Internal organ eval
  • Large joints
  • Muscles, tendons, ligaments around joints
  • Intaoperative application
72
Q

What is identification is limited with US?

A

Spinal evaluation, perispinal structures, and measuring muscle volume

73
Q

What does the film look like when the film has too much contrast?

A

Appears too White and Black (over-exposed)

74
Q

How would you correct a film with too much contrast?

A

increase kVp by 15% and dividing mAs by 2

75
Q

When a film has too little contrast (too grey overall, washed out, dull) how is it corrected?

A

lowering kVp, which will require mAs by 2x to correct density

76
Q

What landmark can be checked for film density?

A

ID blocker

77
Q

If the film is too dark what could be the cause?

A

Processor

78
Q

How would the density be fixed if the film is too dark?

A

Decrease the mAs (Leave the kVp alone)

79
Q

What would be the consequence of excessive mAs &/or kVp, high developer temperature, chemicals too strong?

A

Film appears overexposed

80
Q

What happens if the prossesor chemicals were just changed or replenishment rate is too high?

A

The film appears overexposed

81
Q

Bone pathology substantially reducing bone density does what to film image?

A

Overexposed appearance

82
Q

Mis-measurement of the patient results in a wrong technique causing what?

A

Errors in density

Radiographic Technique I (2 decks)

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