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Fluoro Cram > Part 2: Equipment > Flashcards

Part 2: Equipment Flashcards

1
Q

What make fluoroscopy images brighter?

A

Image intensifiers

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2
Q

X-ray tubes in fluoroscopy usually operate at ___ to ___mA

A

3 to 5

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3
Q

Cathode filament and anode in X-ray tube are both made of what?

A

Tungsten

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4
Q

What makes tungsten a better producer of X-rays?

A

High melting point
High atomic number

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5
Q

Purpose of image intensifier

A

Electronically amplify brightness of the image

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6
Q

Purpose of each part of image intensifier:

  1. Vacuum bottle/glass envelope
  2. Input layer
  3. Electronic lens
  4. Output phosphor
A
  1. Keep air out
  2. Convert X-rays to electrons
  3. Focus the electrons
  4. Convert energy of electrons into visible light
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7
Q

Brightness gain is the ability of the ___ to increase the illumination level of the image

A

Image intensifier

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8
Q

Brightness gain is the product of what 2 things?

A

Minification gain

Flux gain

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9
Q

Minification gain is simply ___, NOT ___.

A

Increase in brightness or intensity

NOT improvement in quality

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10
Q

Does a smaller or larger image intensifier produce a better image?

A

Smaller

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11
Q

When is a 9” vs 6” mode used for image intensifiers?

A

9”: large anatomic areas

6”: better image quality but size is unimportant

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12
Q

What affects image intensifier image quality? (4)

A
  1. Quantum mottle
  2. Contrast
  3. Resolution
  4. Distortion
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13
Q

Mottle is more visible in a (high/low) resolution, (high/low) contrast system

A

High, high

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14
Q

Mottle can be adjusted by changing what two exposure factors?

A

kVp and mA

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15
Q

The ratio of brightness between two adjacent areas of a fluoroscopy image is called what?

A

Intensifier contrast

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16
Q

Is contrast better with cesium iodide or zinc cadmium sulfide tubes?

A

Cesium iodide

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17
Q

Contrast ratios for modern image intensifiers exceed ___

A

15:1

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18
Q

What happenes to an image intensifier if the input phosphor does not absorb all the photons in the X-ray beam?

A

Contrast is diminished

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19
Q

What happens to an image intensifier if there is retrograde light flow from the output phosphor?

A

Diminishes contrast

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20
Q

What portion of the image intensifier has the greatest resolution?

A

The central portion

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21
Q

Bigger intensifier = (more/less) distortion

Why?

A

More

Because the further an electron is from the center, the more difficult it is to focus

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22
Q

What kind of distortion is the consequence of projecting the image on a curved input phosphor to a flat output phosphor?

A

Pincushion distortion

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23
Q

When is pincushion distortion reduced?

A

When magnification modes are used

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24
Q

With pincushion distortion, the image is magnified to a greater extent towards the (center/periphery), resulting in ___.

A

Periphery

Vignetting

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25
Q

What part of the fluoroscopy unit keeps the light output of the image intensifier constant over variations of pt thickness and density (attenuation)?

A

Automatic brightness control (ABC)

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26
Q

The ABC interfaces with the ___ to adjust kVp and mA in a quick feedback loop

A

X-ray generator

27
Q

Operating fluoroscopy at higher kVp values results in what happening with the beam?

A

Increased transmission of the beam through the pt = less radiation required

28
Q

If kVp was increased by 15%, how much change in brightness would occur? How much would the ABC adjust the mAs?

A

15% increased in kVp = double brightness = mAs reduced by 50%

29
Q

What happens to image contrast as kVp is increased?

A

It degrades

30
Q

When should lower vs higher kVp be used?

A

Lower: low contrast objects/iodine based contrast (angio, chole, etc.)

Higher: high contrast/barium (GI, etc.)

31
Q

4 types of ABC circuits

A
  1. Variable mA, preset kVp
  2. Variable mA with kVp following
  3. Variable kVp with selected mA
  4. Variable kVp, variable mA
32
Q

What does being a closed circuit video system mean?

A

The video signals are transmitted via cables rather than air

33
Q

What does the vidicon tube of the vidicon camera contain?

A

The vidicon target

the electron gun

34
Q

How does the vidicon tube produce a television picture?

A

The electron gun produces the electron beam that is focused onto the vidicon target which produces the picture

35
Q

What is the downside to vidicon tubes?

A

Image lag

36
Q

What is interlaced scanning in a closed circuit monitor system?

A

The odd lines of the produced image are scanned first then the even lines are rescanned with the same image

37
Q

A vidicon camera (enhances/reduces) contrast by a factor of 0.8 and the monitor (enhances/reduces) contrast by a factor of 2.

This results in a net (improvement/deterioration) of the image contrast.

A

reduces

enhances

improvement

38
Q

Traditionally, how many scan lines per picture are produces with a fluoroscopy television system?

A

525

39
Q

What factors affect television image quality in the normal closed-circuit fluoro system? (5)

A

Horizontal resolution
Vertical resolution
Contrast
Brightness
Lag

40
Q

Horizontal resolution is the sum of what three things?

A

scan lines + frame rate + frequency rate

41
Q

Vertical resolution (lp/mm) = ?

A

horizontal lines across the image

_______________________________
2 x diameter of object in mm

42
Q

Formula for the Kell factor

A

vertical resolution
___________________
# scan lines

43
Q

What is the Kell factor for a 525 scan line system?

A

0.7

44
Q

What is lag?

A

When the television image is blurred when the fluoroscopic tower is moved rapidly

45
Q

Is lag caused by the image intensifier?

A

No

46
Q

Which type of camera is used for CV procedures due to better contrast and less motion blurring?

A

Plumbicon camera

47
Q

What are some advantages of the charge-coupled device (CCD) cameras?

A

Smaller unit

Lower power consumption

Lower price

Longer life

Less lag

48
Q

What are the two typical ways of recording dynamic (motion) images with analog devices?

A

Video tape recording

Cinefluorography

49
Q

There is an up to 95% patient dose reduction when utilizing ___ during fluoroscopy

A

video disc recording.

50
Q

____ photograph the image on the output phosphor of the image intensifier

A

Photospot film cameras

51
Q

Which has higher radiation dose rate per frame: fluoroscopy or spot film cameras?

Why?

A

Spot film cameras dose 20-50x higher per frame rate

Used much higher mA

52
Q

A 70mm roll film in a spot film camera can acquire up to ___ frames/sec.

A

12

53
Q

With an individual spot film camera, what happens to pt dose and image quality as film size increased?

A

Both increased

54
Q

Which has lower pt radiation exposure: an individual 105mm spot film or a cassette-loaded spot film?

A

Always the individual spot film

55
Q

Where is the spot film positioned?

A

Between the pt and the image intensifier

56
Q

Spot-filming mA with conventional cassette

A

100+

57
Q

Analog-to-digital converter

Digital-to-analog converter

A

ADC: converts the original data to store an image in digital processor memory

DAC: converts the stored digital image back into analog so it can be viewed

58
Q

3 basic types of studies performed with digital fluoro.

Which is most used?

A
  1. Mask mode fluoro (most used)
  2. K-edge fluoro
  3. Time interval difference imaging
59
Q

What type of imaging:

Pros: instant playback, possible subsequent image enlargement

Con: resolution is less than that of film

A

Digital photospot imaging

60
Q

Regulations limit the maximum tabletop dose rate of ____ when acquiring images without a recording device such as video tape.

A

20 rad/min

61
Q

High level fluoroscopy is generally used for what procedures?

A

Interventional/cardio/angio

62
Q

Rate the image intensification viewing systems from highest to lowest resolution:

optical mirror
videotape
video (real-time)
16mm cine film
35mm cine film
spot cassette
spot 105mm
spot 70mm
digital

A

highest: optical mirror
cassette spot
105mm spot
70mm spot
35mm cine
16mm cine
digital
video real-time
lowest: videotape

63
Q

High or low pt radiation dose?

spot film
photospot/digital
cine
videotape/disc

A

spot: high
photospot/digital: low
cine: high
videotape/disc: low

64
Q

Framing frequency for each:

spot film
photospot/digital
cine
videotape/disc

A

spot: 1/sec
photospot/digital: 12/sec
cine: 60/sec
videotape/disc: 60 rpm

Fluoro Cram (8 decks)

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