Principles of fluroscopy equipment and function

Question 1

name 4 reasons why fluoroscopy would be used

Answer 1

1) need for dynamic imaging
2) Diagnosis
3) Asses function
4) Guide intervention

Question 2

Name the three configurations that the fluoroscopy equipment can be

Answer 2

1) under-couch tube
2) over-couch tube
3) C-arm

Question 3

Name 3 advantages for the under-couch tube

Answer 3

1) lead skirt to reduce scatter
2) able to reduce object to detector distance as much as possible
3) Conventionally used for angiography

Question 4

name 5 disadvantages to the under-couch tube

Answer 4

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

Question 5

name 5 advantages to the over-couch tube

Answer 5

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

Question 6

name 4 advantages for the C-arm

Answer 6

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

Question 7

`Name the disadvantage of the C-arm

Answer 7

1)need to be aware where the x-ray tube is pointing

Question 8

what 7 things make up the image intensifier?

Answer 8

1) attenuated x-ray beam
2) input phosphor
3) photocathode
4) Focusing electrodes
5) Output phosphor
6) Video camera
7) TV

Question 9

what does the input phosphor do

Answer 9

converts x-ray photons into fluorescent light

Question 10

what is the input phosphor made of

Answer 10

caesium iodide

Question 11

what is the input phosphor coupled to

Answer 11

the photocathode

Question 12

what does the input phosphor do to the thickness of the phosphor

Answer 12

increases the thickness- therefore more photons absorbed and converted into light

Question 13

what is the photocathode made of

Answer 13

caesium antimony

Question 14

what does the photocathode to

Answer 14

converts light into electrons

Question 15

What two things happen in the vacuum tube

Answer 15

1) electrons are accelerated from the cathode to the anode

2) then focused down in size by focusing electrodes

Question 16

what is the output phosphor made of

Answer 16

silver activated zinc-cadmium sulphide

Question 17

what happens in the output phosphor

Answer 17

electrons hit the output phosphor and are turned into green light

Question 18

how many light photons are there in the output phosphor per incident electron

Answer 18

2,000

Question 19

name the two reasons why the resultant image is brighter and smaller

Answer 19

1) Flux gain

2) minification gain

Question 20

what is flux gain

Answer 20

for every light photon generated at the input phosphor there are (x100) light photons at the output phosphor

Question 21

what is minification gain

Answer 21

same photons but in a smaller area

Question 22

23cm II has output window of

Answer 22

1.5-6cm

Question 23

what is the minification gain of 23cm II

Answer 23

120

Question 24

what is the purpose of the automated brightness control (3 points)

Answer 24

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

Question 25

name 5 examples of procedures that use fluoroscopy

Answer 25

1) GI studies
2) angiography
3) ERCP
4) HSG
5) Theatre

Question 26

name three types of GI studies

Answer 26

1) barium enema
2) barium swallow
3) water soluble studies

Question 27

name two types of theatre

Answer 27

1) orthopaedic

2) Pacing theatre