Principles of fluroscopy equipment and function Flashcards
name 4 reasons why fluoroscopy would be used
1) need for dynamic imaging
2) Diagnosis
3) Asses function
4) Guide intervention
Name the three configurations that the fluoroscopy equipment can be
1) under-couch tube
2) over-couch tube
3) C-arm
Name 3 advantages for the under-couch tube
1) lead skirt to reduce scatter
2) able to reduce object to detector distance as much as possible
3) Conventionally used for angiography
name 5 disadvantages to the under-couch tube
1) mostly operated from the tube itself
2) higher dose to user due to tube position
3) more enclosed for the patient
4) limited access to the patient
5) unable to angle the tube
name 5 advantages to the over-couch tube
1) usually operated form behind the control panel
2) able to lower closer to the floor
3) easy to use ad standard tube for table work
4) easy to access the patient
5) lower dose
name 4 advantages for the C-arm
1) can be either over-couch or under-couch
2) mobile C-arm can be used in theatre
3) patient doesn’t need to move as much
4) Replacing over and under-couch tubes
`Name the disadvantage of the C-arm
1)need to be aware where the x-ray tube is pointing
what 7 things make up the image intensifier?
1) attenuated x-ray beam
2) input phosphor
3) photocathode
4) Focusing electrodes
5) Output phosphor
6) Video camera
7) TV
what does the input phosphor do
converts x-ray photons into fluorescent light
what is the input phosphor made of
caesium iodide
what is the input phosphor coupled to
the photocathode
what does the input phosphor do to the thickness of the phosphor
increases the thickness- therefore more photons absorbed and converted into light
what is the photocathode made of
caesium antimony
what does the photocathode to
converts light into electrons
What two things happen in the vacuum tube
1) electrons are accelerated from the cathode to the anode
2) then focused down in size by focusing electrodes
what is the output phosphor made of
silver activated zinc-cadmium sulphide
what happens in the output phosphor
electrons hit the output phosphor and are turned into green light
how many light photons are there in the output phosphor per incident electron
2,000
name the two reasons why the resultant image is brighter and smaller
1) Flux gain
2) minification gain
what is flux gain
for every light photon generated at the input phosphor there are (x100) light photons at the output phosphor
what is minification gain
same photons but in a smaller area
23cm II has output window of
1.5-6cm
what is the minification gain of 23cm II
120
what is the purpose of the automated brightness control (3 points)
1) it is important that fluoroscopy procedures follow the ALARP principle
2) Brightness will change with the part of the body- some areas are more radiolucent than others
3) A monitoring device samples the brightness of the image output and adjusts mA or kV accordingly
name 5 examples of procedures that use fluoroscopy
1) GI studies
2) angiography
3) ERCP
4) HSG
5) Theatre
name three types of GI studies
1) barium enema
2) barium swallow
3) water soluble studies
name two types of theatre
1) orthopaedic
2) Pacing theatre
