Flouroscopy

Question 1

Purpose of an image intensifier

Answer 1

amplify low x-ray signals

Question 2

how does an image intensifier work?

Answer 2

x-ray converted into light and then to electrons staright away by a phosphor with a photocathode at the back

electrons accelerated through the tube by ana electric field

electrons focused by a lens and make sure they don’t lose their spatial pattern

electron energy converted into light photons at the end of the image intensifier

Question 3

What are imaging artefacts in image intensifiers?

Answer 3

veiling glare

vignetting

S distortion

Question 4

What is veiling glare due to

Answer 4

due to scattering in the output window

Question 5

What is vignetting in image intensifiers?

Answer 5

Resolution/ brightness is best in the middle of the image

Question 6

What is S-distortion in Image intensifiers?

Answer 6

spatial warping of the image in an s-shape, due to magnetic field abnormalities/ the earth magnetic field

Question 7

What is contrast ratio in Image intensifiers?

Answer 7

describes the ability of the II to convey the contrast of an object.

Indirect measurement of veiling glare

Question 8

What does QDE stand for?

Answer 8

Quantum detection efficiency

Question 9

What is Quantam Deficiency Efficiency in Image Intensifiers?

Answer 9

fraction of incident x-ray photons that interact with the II

Question 10

What are the advantages of pulse vs continuous fluoroscopy?

Answer 10

Pulsed:

• more x-rays and thus better resolution,
• lower FPS.
• shorter exposure time so less blurring