Fluoroscopy week 3 cont. Flashcards
what is a blotchy or grainy appearance caused by insufficient radiation to create a uniform image
quantum mottle
quantity of photons is controlled by the
mA and time settings
the most commonly used fluoroscopic viewing system is
video
video uses
closed circuit video
fluoro video cameral use a
vidicon or plumbicon tube or a charge-coupled device (CCD)
both tubes are _ in operation
similar
Plubicon tube has a _ time than a Vidicon tube
faster response
consists of a
control grid w/a cathod
cathode consists of pairs of _ serve to cause the election beam to scan the target in a path known as a
deflecting coils
Raster pattern
commercial TV uses
525 horizontal line pattern
High-resolution video systems now offer
1050 Line systems
for cathode the electron beam scans across the screen nearly _
1,000,000 times per min.
to avoid flicker each scan is divided into two halves 1st half is _ and 2nd half is
even # lines
odd # lines
what reduces the resolution and is the primary disadvantage of a video viewing system
Raster Pattern
The output phosphor of the image intensification tube is coupled with the face plate of the vidicon tube by fiber optics or optical lenses
Anode
for anode, the signal plate is thin enough to _ yet thick enough to _ out of the tube
transmit light
conduct the electronic signal
Vidicon tubes use _
Plumbicon tubes use _transmit light
conduct the electronic signal
Trisulfide
Lead oxide
what tube is connected to the output screen of the image intensification tube by either fiber optics or an optical lens system
vidicon tube
vidicon tube is unable to allow for
spot filming
light photons are transmitted to the
signal plate and target
spot filming requires an
optical lens system
CCD means
charge-coupled devise
what is a semiconducting device capable of storing a charge from light photons striking a photosensitive surface
ccd
when light strikes the photoelectric cathode of the CCD, electrons are released based on the
intensity of incident light
CCD’s have extremely fast _ which eliminates what
discharge time
image lag
CCD’s are useful in
cardiac catheterization
CCD’s are more sensitive than
video tubes
CCD’s work at
lower voltage (longer life)
CCD’s have what type of resolution
acceptable
True/False CCD’s don’t damage easily
true
video monitors are a
tv tube
what consists of a vacuum tube with a fluorescent phosphor coated on the inside of the front screen and a election gun with deflecting and focusing electromagnets
cathode ray tube
for the video monitor the electron gun is the
while the Anode is plated onto the
cathode
front screen
what follows the same raster pattern used by the camera
gun
phospher crystals emit
light when struck by e and transmit it as a visual image
what is the most restrictive element in the fluoro imaging chain resolution
video monitor
magnification of this image by the video camera or an optical system can increase
resolution significantly
video monitors operate in the _ and can emit
low kV
low energy x-rays
for video monitor, what can be adjusted with controls on the monitor itself
contrast and brightness
digital fluoroscopy is achieved through the use of a
thin film transistor
Thin film transistor replaces what
the image intensifier in nondigital fluoro systems
TFT is a _ unit with a _ connected to each pixel element
pixelated
photodiode
A unique feature of TFT’s is that they are relatively
insensitive to x-ray photons
what is added to the image receptor to increase sensitivity
Csl Scintillator element
what resolution isn’t as high as radiography
Why?
Digital Fluoro
the clinical value is outweighed by pt. exposure concerns
Dynamic systems are
recordings of fluoro images has been limited to cine film and videotape
