IP
what is the main function of the image intensifier in a fluoroscopy unit?
convert the x-ray beam into bright visible light.
what is the job of the photocathode in an image intensifier of a fluoroscopy unit?
what is a flat-panel detector (FPD)?
modern solid-state image receptor used in digital imaging.
what is the biggest disadvantage of FPD's?
high cost
which cells are responsible for photopic vision?
cone cells
what is the sequence of image intensification?
x-rays-light-electrons-light-monitor
where is the electrostatic lens located in an image intensifier of a fluoroscopy unit?
along the full length of the image intensification tube
what type of systems are most flat-panel detectors (FPD)?
in-direct solid-state systems.
what are the advantages of FPD's?
better stability, lower patient dose, wider dynamic range.
what is scotopic vision?
low light or night vision
what does the input phosphor do in an image intensifier for a fluoroscopy unit?
converts incoming x-ray photons into light photons.
what is the job of the electrostatic lens in an image intensifier of a fluoroscopy unit?
directs or focuses the path of electron from the photocathode to the surface of the output phosphor.
how do indirect FPD systems work?
x-rays converted to light, and then converted to an electronic signal
what is brightness gain?
increase in image brightness in fluoro
which cells are responsible for scotopic vision?
rod cells
what material is the input phosphor in an image intensifier made of in a fluoroscopy unit?
what is the job of the output phosphor in an image intensifier of a fluoroscopy unit?
what is a flat-panel detector composed of?
thallium-activated cesium iodide
what is the formula for brightness gain?
BG= minification-gain x flux-gain
what is the apparent loss of detail and brightness at the edges of a fluoroscopic image called?
vignetting (pin cushion distortion)
where is the photocathode located in an image intensifier of a fluoroscopy unit?
bonded directly to the input phosphor.
what is the output phosphor made out of?
zinc cadmium sulfide (ZnCds)
What is the key difference between indirect versus direct FPD?
indirect= lower dose
direct= better spatial resolution.
what is photopic vision?
bright light vision
what does vignetting result in?
loss of resolution