Ch. 5: Indirect Conversion

Question 1

What are the two steps in indirect conversion?

Answer 1

X-rays are converted to light, then light is converted to an electrical signal.

Question 2

What materials are used as scintillators in indirect conversion?

Answer 2

Gadolinium oxysulfide (Gd2O2S) or thallium-doped cesium iodide (CsI[Tl]).

Question 3

What is the phosphor layer called in indirect conversion?

Answer 3

The scintillation layer.

Question 4

What is the difference between structured and unstructured scintillation layers?

Answer 4

Unstructured layers scatter more light, reducing resolution, while structured layers guide light more efficiently.

Question 5

What device converts light into electrical charge in indirect conversion?

Answer 5

A photodetector, such as a hydrogenated amorphous silicon (a-Si:H) photodiode array.