ABR ABR Imaging Physics and Equipment

Question 1

What is the primary source of image noise in computed tomography (CT) imaging?

Accepted Answer

Quantum noise from limited photon statistics

Answer

Electronic noise from the detector

Answer

Patient motion

Answer

Scatter radiation

Question 2

In CT imaging, what does the CT number (Hounsfield unit) of water equal?

Accepted Answer

0 HU

Answer

1000 HU

Answer

-1000 HU

Answer

500 HU

Question 3

Which parameter most directly controls spatial resolution in a CT scanner?

Accepted Answer

Detector aperture and reconstruction kernel

Answer

mAs setting

Answer

kVp setting

Answer

Pitch factor

Question 4

What is the purpose of the modulation transfer function (MTF) in evaluating imaging system performance?

Accepted Answer

Quantifies spatial resolution by measuring how faithfully a system reproduces contrast at different spatial frequencies

Answer

Measures image noise spectrum

Answer

Evaluates detector uniformity

Answer

Characterizes temporal resolution

Question 5

In digital radiography, what is the Detective Quantum Efficiency (DQE) a measure of?

Accepted Answer

How efficiently a detector converts incident x-ray quanta into useful image signal relative to an ideal detector

Answer

The fraction of x-rays absorbed by the detector

Answer

The dynamic range of the detector

Answer

The spatial resolution at the detector surface

Question 6

What is the half-value layer (HVL) used to describe in diagnostic x-ray imaging?

Accepted Answer

The thickness of material that reduces x-ray beam intensity by 50%

Answer

The depth of maximum dose in tissue

Answer

The layer where scatter is maximum

Answer

The distance over which mAs doubles