Part 2: Equipment

Question 1

What make fluoroscopy images brighter?

Answer 1

Image intensifiers

Question 2

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

Answer 2

3 to 5

Question 3

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

Answer 3

Tungsten

Question 4

What makes tungsten a better producer of X-rays?

Answer 4

High melting point
High atomic number

Question 5

Purpose of image intensifier

Answer 5

Electronically amplify brightness of the image

Question 6

Purpose of each part of image intensifier:

1. Vacuum bottle/glass envelope
2. Input layer
3. Electronic lens
4. Output phosphor

Answer 6

1. Keep air out
2. Convert X-rays to electrons
3. Focus the electrons
4. Convert energy of electrons into visible light

Question 7

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

Answer 7

Image intensifier

Question 8

Brightness gain is the product of what 2 things?

Answer 8

Minification gain

Flux gain

Question 9

Minification gain is simply ___, NOT ___.

Answer 9

Increase in brightness or intensity

NOT improvement in quality

Question 10

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

Answer 10

Smaller

Question 11

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

Answer 11

9”: large anatomic areas

6”: better image quality but size is unimportant

Question 12

What affects image intensifier image quality? (4)

Answer 12

1. Quantum mottle
2. Contrast
3. Resolution
4. Distortion

Question 13

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

Answer 13

High, high

Question 14

Mottle can be adjusted by changing what two exposure factors?

Answer 14

kVp and mA

Question 15

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

Answer 15

Intensifier contrast

Question 16

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

Answer 16

Cesium iodide

Question 17

Contrast ratios for modern image intensifiers exceed ___

Answer 17

15:1

Question 18

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

Answer 18

Contrast is diminished

Question 19

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

Answer 19

Diminishes contrast

Question 20

What portion of the image intensifier has the greatest resolution?

Answer 20

The central portion

Question 21

Bigger intensifier = (more/less) distortion

Why?

Answer 21

More

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

Question 22

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

Answer 22

Pincushion distortion

Question 23

When is pincushion distortion reduced?

Answer 23

When magnification modes are used

Question 24

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

Answer 24

Periphery

Vignetting

Question 25

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

Answer 25

Automatic brightness control (ABC)

Question 26

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

Answer 26

X-ray generator

Question 27

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

Answer 27

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

Question 28

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

Answer 28

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

Question 29

What happens to image contrast as kVp is increased?

Answer 29

It degrades

Question 30

When should lower vs higher kVp be used?

Answer 30

Lower: low contrast objects/iodine based contrast (angio, chole, etc.) Higher: high contrast/barium (GI, etc.)

Question 31

4 types of ABC circuits

Answer 31

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

Question 32

What does being a closed circuit video system mean?

Answer 32

The video signals are transmitted via cables rather than air

Question 33

What does the vidicon tube of the vidicon camera contain?

Answer 33

The vidicon target the electron gun

Question 34

How does the vidicon tube produce a television picture?

Answer 34

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

Question 35

What is the downside to vidicon tubes?

Answer 35

Image lag

Question 36

What is interlaced scanning in a closed circuit monitor system?

Answer 36

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

Question 37

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.

Answer 37

reduces enhances improvement

Question 38

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

Answer 38

525

Question 39

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

Answer 39

Horizontal resolution Vertical resolution Contrast Brightness Lag

Question 40

Horizontal resolution is the sum of what three things?

Answer 40

scan lines + frame rate + frequency rate

Question 41

Vertical resolution (lp/mm) = ?

Answer 41

# horizontal lines across the image _______________________________ 2 x diameter of object in mm

Question 42

Formula for the Kell factor

Answer 42

vertical resolution ___________________ # scan lines

Question 43

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

Answer 43

0.7

Question 44

What is lag?

Answer 44

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

Question 45

Is lag caused by the image intensifier?

Answer 45

No

Question 46

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

Answer 46

Plumbicon camera

Question 47

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

Answer 47

Smaller unit Lower power consumption Lower price Longer life Less lag

Question 48

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

Answer 48

Video tape recording Cinefluorography

Question 49

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

Answer 49

video disc recording.

Question 50

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

Answer 50

Photospot film cameras

Question 51

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

Answer 51

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

Question 52

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

Answer 52

12

Question 53

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

Answer 53

Both increased

Question 54

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

Answer 54

Always the individual spot film

Question 55

Where is the spot film positioned?

Answer 55

Between the pt and the image intensifier

Question 56

Spot-filming mA with conventional cassette

Answer 56

100+

Question 57

Analog-to-digital converter Digital-to-analog converter

Answer 57

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

Question 58

3 basic types of studies performed with digital fluoro. Which is most used?

Answer 58

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

Question 59

What type of imaging: Pros: instant playback, possible subsequent image enlargement Con: resolution is less than that of film

Answer 59

Digital photospot imaging

Question 60

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

Answer 60

20 rad/min

Question 61

High level fluoroscopy is generally used for what procedures?

Answer 61

Interventional/cardio/angio

Question 62

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

Answer 62

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

Question 63

High or low pt radiation dose? spot film photospot/digital cine videotape/disc

Answer 63

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

Question 64

Framing frequency for each: spot film photospot/digital cine videotape/disc

Answer 64

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