ABR Imaging Physics and Equipment Flashcards
6 cards from real ABR practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 ABR Imaging Physics and Equipment flashcards as text
What is the primary source of image noise in computed tomography (CT) imaging?
Answer: Quantum noise from limited photon statistics
Quantum noise, arising from statistical fluctuations in the number of x-ray photons detected, is the dominant source of image noise in CT.
In CT imaging, what does the CT number (Hounsfield unit) of water equal?
Answer: 0 HU
By definition, water has a CT number of 0 Hounsfield units (HU), with air at −1000 HU and dense bone typically above +400 HU.
Which parameter most directly controls spatial resolution in a CT scanner?
Answer: Detector aperture and reconstruction kernel
Spatial resolution in CT is primarily determined by the detector aperture size and the reconstruction (convolution) kernel used in filtered back-projection.
What is the purpose of the modulation transfer function (MTF) in evaluating imaging system performance?
Answer: Quantifies spatial resolution by measuring how faithfully a system reproduces contrast at different spatial frequencies
The MTF describes how well a system transfers contrast from the object to the image as a function of spatial frequency, with higher MTF values indicating better resolution.
In digital radiography, what is the Detective Quantum Efficiency (DQE) a measure of?
Answer: How efficiently a detector converts incident x-ray quanta into useful image signal relative to an ideal detector
DQE measures the efficiency with which a detector uses the available x-ray quanta for image formation, accounting for both sensitivity and noise added by the detector.
What is the half-value layer (HVL) used to describe in diagnostic x-ray imaging?
Answer: The thickness of material that reduces x-ray beam intensity by 50%
The half-value layer (HVL) is the thickness of a specified material required to reduce the x-ray beam intensity to half its original value, and characterizes beam quality (hardness).