Fluoroscopy Flashcards
Fluoroscopy
dynamic radiographic examination, compared to diagnostic radiography; active diagnosis
who was credited with the invention of Fluoroscopy
Thomas A. Edison; 1896
what is the imaging receptor called for Fluoroscopy
Fluoroscopy screen
types of Fluoroscopy equipment
C-arms, so that the tube is always alined with the Floro. screen. under table units and over table units.
what is the carriage
arm that supports the equipment suspended over the table
are floroscreens only suspended over the table?
they can either be suspended over the table or placed under the table
how do Floro towers operate; technique wise?
longer period of time at a lower mA
what is the mA range?
.5-5.0mA
how does the X ray tube Floro. collimate
electronically controlled shutters
magnification gain formula
input screen diameter^2/ output screen diameter^2
Flux gain is the measurement of what
measurement of the increase in light photons due to the conversion efficiency of the output screen
how can brightness gain be calculated?
minification gain X flux gain
Automatically maintain satisfactory fluoroscopic image density and contrast, is referred to as
ABC= Automatic Brightness Control
what does ABC do
controls density compensation; vary the mA and kVp
how do you regulate the primary beam of a flouro
varying kVp, mA, and pulse time
resolution in flouro
depends on geometrical factors
types of distortion in flouro
size and shape
how is size distortion created
Magnification caused by OID
how is shape distortion seen
geometric problems in the shape of the image intensification tube
Vignetting effect
edge distortion prob. in image intensification tube
Quantum mottle in flouro ?
basically anything that is affecting the total number of photons arriving at the retina; radiation output, beam attenuation by the subject, the conversion efficiency of the input screen, magnification gain, flux gain, total brightness gain, viewing system, and the distance of the eye from the viewing system
Video Viewing systems
commonly used in fluoroscopic viewing system
it is made up of video camera attached to the image intensification tube output phosphor and a display monitor for viewing.
what is a video monitor in flouro
high- resolution output screen that receives the final processed signal from the fluoroscopic processor
what factors separate Digital fluoroscopy
high speed generator operating in a pulse progressive fluoroscopy mode; basically keeps the X-ray production of the X-ray tube in sync with the detector signal, so that pulses of the signal are received by the image processing unit.
interrogation time is what
the length of time required for the generator to come on and achieve the necessary kVp and mAs levels
Digital flouro pixels rage from
200 um and 300 um (1-2 Ip/mm)
what is the processor of most digital fluoroscopy systems?
8-bit processing capability
what is the amount of exposure to skin that a flouro system gives to the patient
1-3 R/min; should not exceed 10 R/min
lead gloves have what Pb/eq
.5 mm Pb/eq
lead aprons should have what Pb/eq
.5 mm Pb/eq
the slot where the gonad shild goes should have how much Pb/eq
.25 mm Pb/eq
image intensifier
increase brightness, which means no need for night vision (scotopic)
its unit is Lamberts (L)
brightness depends on mA(less than 5 mA not mAs remember (single phase)) kVp and part
what is the typical fluoro. intensity
2.1 R/min for each mA at 80 kVp, and NO more than 10R/min at table top
overhead intensity is?
mR
what is the process if the image intensifier
incident x-ray beam> input phosphor> emits light> photocathode> electrons> photoemission> electrostatic lens guide the electrons to stimulate the output phosphor>emits light
ABS
automatic brightness stabilization
AGC
automatic gain control; adjusts the degree of amplification of the electronic signal
does AGC affect patient dose
does not very patient dose
what is AGC affect on image noise
increases image noise
flux gain formula
of output light photons/ # of input light photons
magnification formula for conventional rad.
SID/SOD
what is the formula for fluoroscope magnification
ratio if the input diameter (without a square)
what are the advantages of multi field imaging
smaller area viewed magnification, dimmer, but improves image quality
how do we calculate patient dose
ratio of input diameter squared
distal end of the T.V camera
has an electrical gun that shoots electrons toward the proximal end. gun has a filament and via thermionic emission, emits electrons, then they go to the proximal end that has the target. light from the output Phosphor goes to the target. THE VIDEO SIGNAL CAN ONLY BE CREATED IF BOTH, THE LIGHT AND THE ELECTRONS HIT THE TARGT AT THE SAME PLACE AT THE SAME TIMEW
TV Monitor
monitor changes video signal to a visible image
units are lp/mm
what is Voxel?
volume of each pixel.
it is the weakest link to resolution
what is the order from highest to lowers dose
cassette spot film, cine, then spot film
how do you calculate minification
diameter of input^2/ diameter of output^2
when is Flux increased
when mA is increased
what is inside the TV monitor
cathode ray tube
where is a spot film cassette placed and what phase generator is used when taking the image
it is placed between the image intensifier and the patient
it uses a three phase generator
what are spot film 105, what generator is used and is it in continuous flouro when exposing the 105 film
basically like the ancient film rolls but twice or three times that size.
it exposes one frame at a time
it uses a single phase generator on exposure
photo signal from output phosphor of the Image intensifier then its converted to an image with spot film
optic system
used in early fluoroscopy.
uses reflective mirrors to direct the output screen image to the viewer
how is a cine film used, what generator does it use and is it a continuous flouro
cine films are used in Cath lab
uses a single phase generator
has a higher exposure dose than 105 film b/c of the continuous flouro; has better resolution as well
where is the optic system located
at the distal end of the image intensifier
where is the T.V camera located and how does it get to the computer
at the distal end of the image intensifier and can go from the image digitizer and send a digital signal to the computer or can go from T.V camera to TV monitor via video signal then to the computer via digital signal
where is the spot film camera
is at the distal end of the image intensifier
what are the cine sizes
35mm or 16mm cine
what are the spot film sizes
105, 90, and 70mm spot film
move much brighter does brightness Gian make an image
5000 to 20,000 times brighter
