Radiographic Image Acquisition

Question 1

What does CR stand for in radiology?

Answer 1

Computed radiography

Question 2

Does CR require more or less radiaiton than analogue films?

Answer 2

less, although you get better quality with more radiation

Question 3

Can you re-use CR casettes?

Answer 3

yes, you can reset them and then use them again

Question 4

How does CR work?

Answer 4

Image plates are exposed to radiation,

the energy x-rays is trapped in the plate,

then this latent image is read out using a red laser

Question 5

How does the resolution of CR compare to analogue radiography?

Answer 5

less good, as the laser can only focus on a point so small, and then it will assume all light from that area is from the one point (some aliasing)

Question 6

What is used to resent CR cassettes?

Answer 6

a bright light source

Question 7

What is DR in radiography?

Answer 7

Digital radiography

Question 8

What’s the trade-off between thick or thin screens in DR?

Answer 8

thick screens have better absorption but a worse resolution (as the energy can go down at a bit of an angle)

Question 9

What are the basic components of a DR detecter

Answer 9

Phosphor to convert x-rays to light

Photodiode array: to convert light to an electric signal

Readout electronics

Question 10

What it a k-edge

Answer 10

a sudden increase in x-ray absorption when the energy of the X-rays is just above the binding energy of the innermost electron shell of an atom

Question 11

How does dual-energy imaging work?

Answer 11

digitally subtract certain tissues - by taking multiple sets of images with k-edges related to the materials trying to be imaged