Analog Vs. Digital
How do digital images differ from analog images?
Digital images are composed of pixels with discrete values
Air kerma is best described as what?
Energy absorbed in air measured in gray
Which factor has the greatest influence on spatial resolution in digital imaging?
Pixel size
What type of noise is caused by the random arrival of x-ray photons?
Metastable trapped electrons
Which digital imaging system replaced screen-film?
CR
What is the primary purpose of KSTD?
Represent a standardized reference exposure
Pixel bit depth primarily affects what image property?
Contrast resolution
Which type of noise originates from the patient's anatomy?
Anatomic noise
What is the primary function of the infrared laser in the CR reader?
Stimulate the trapped electrons to emit light
What was the major advancement provided by computed radiography (CR)?
It converted screen-film radiography to a digital format
Which value represents the actual exposure received by the image receptor?
KTGT
How many gray levels are available in a 10-bit imaging system?
1024
Increasing SNR generally requires what?
Higher patient exposure due to more mAs
Which CR reader component ensures consistent spatial resolution?
Laser beam diameter
How does the latent image exist in digital imaging?
Briefly until processing occurs
A deviation index of -2 indicates what?
Underexposure
If the field of view decreases while matrix size remains constant, what happens to pixel size?
It decreases
Detective Quantum Efficiency (DQE) describes what?
Efficiency of converting x-rays into an image signal
CR imaging plates must be erased to do what?
Remove residual latent images
Exposure latitude refers to what detector characteristic?
The detector's range of recordable exposures
What should DI not be used as the sole indicator of image quality?
It does not account for image noise and artifacts.
Modulation transfer function (MTF) is a measure of what?
Spatial frequency accuracy
Which system generally has the highest DQE?
Direct DR using amorphous selenium
Elimination of light spread