Fluoroscopy Test Questions and Answers All Correct
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Course
Fluoroscopy
Institution
Fluoroscopy
Fluoroscopy Test Questions and Answers All Correct
Where is the tower connected? - Answer- To the x-ray tube mount
What does the image intensifier do? - Answer- Increases brightness of image
How much can modern image intensifiers increase brightness? - Answer- 8000 times
What does the i...
Fluoroscopy Test Questions and
Answers All Correct
Where is the tower connected? - Answer- To the x-ray tube mount
What does the image intensifier do? - Answer- Increases brightness of image
How much can modern image intensifiers increase brightness? - Answer- 8000 times
What does the input screen do? - Answer- Absorbs x-ray photons and emits light
photons
What does the photocathode do? - Answer- Absorbs light photons and emits electrons
Where are the electrons accelerated from the photocathode move to? - Answer- Toward
the anode and output screen
What focuses the electrons? - Answer- Electrostatic lenses
What does the output screen do? - Answer- Absorbs the electrons and emits light
photons
What is the input phosphor made of? - Answer- Glass, titanium, steel or aluminum and
coated with cesium iodide crystals
Why are cesium iodide crystals used? - Answer- They have high x-ray photon
absorption and light emission characteristics
How big is the input phosphor? - Answer- 10-35 cm in diameter
How much exit radiation leaving the patient does the input phosphor absorb? - Answer-
About 66%
What does the concave structure of the input phosphor do? - Answer- Enhances
sharpness of the image
What is the phenomenon called when photoelectrons of the photocathode are stuck by
light? - Answer- Photoemission
Where are the electrostatic lenses located? - Answer- Along the inside of the
photocathode
, What range of kVp charges the electrostatic lenses? - Answer- 25-35 kVp
What does the concave structure of the photocathode do? - Answer- Reduces distortion
by maintaining distance between all points on the input screen and output phosphor
What is the focal point? - Answer- The precise location where the photoelectrons cross
What are the parts of the image intensifier? - Answer- Output phosphor, anode(+), glass
envelope, electrostatic lenses(-), photocathode (-), input phosphor
How does the image intensifier convert (starting from bottom with x-ray photons)? -
Answer- X-ray photons, light, photoelectrons, focal point, light
What is brightness gain? - Answer- Measurement of the increase in image brightness or
intensification achieved by the conversions in the image intensification tube
The total gain in brightness comes from a combination of what? - Answer- Acceleration
if photoelectrons (flux gain) and compression of the image size (minification gain)
What is flux gain? - Answer- Ratio of number of light photons at the output phosphor to
the number of x-ray photons at the input phosphor
What is the formula for flux gain? - Answer- = # of output light photons /
# of input x-ray photons
What is minification gain? - Answer- Ratio of light from input phosphor to light at the
output phosphor
Minification gain varies from ____ to ___ - Answer- 40 to 90
What is the formula for minification gain? - Answer- = input phosphor diameter^2/
Output phosphor diameter^2
What is the formula for total brightness gain? - Answer- =flux gain * minification gain
Typical image intensifiers have brightness gains of _____ to _____ - Answer- 5,000 to
30,000
What does automatic brightness control do? - Answer- Maintains the fluoroscopic image
density and contrast at a constant brightness by regulating the radiation output of x-ray
tube
What is magnification? - Answer- Increase in size of an object which allows better
visualization if small structures
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