Image Production & Processing Flashcards

What is the result of using a grid with the central ray directed off-center laterally (lateral decentering)?

Answer: Grid cutoff (decreased density across the entire image)

Lateral decentering causes grid cutoff because the primary beam hits the grid lines at an angle, resulting in uniform decrease in density across the image.

Which image quality factor describes the ability of an imaging system to display two closely spaced objects as distinct structures?

Answer: Spatial resolution

Spatial resolution (detail) is the ability to display small, closely spaced objects as separate entities — measured in line pairs per mm (lp/mm).

What type of image processing reduces high-frequency noise while preserving overall image structure in digital radiography?

Answer: Smoothing (low-pass filtering)

Smoothing (low-pass filtering) reduces high-frequency quantum noise by averaging adjacent pixel values, at the cost of some fine detail.

Which artifact appears as a regular, wavy interference pattern when a stationary grid is used with an oscillating digital detector?

Answer: Moiré pattern

The moiré pattern is an interference artifact caused by the interaction of the grid frequency with the sampling frequency of the digital detector.

In film-screen radiography, what is the primary function of the intensifying screen?

Answer: To convert x-ray energy to visible light, reducing patient dose

Intensifying screens convert x-ray photons into visible light, which exposes the film far more efficiently than direct x-ray exposure, greatly reducing required radiation.

What does the modulation transfer function (MTF) describe in radiographic imaging?

Answer: How faithfully the imaging system reproduces spatial frequencies (sharpness)

MTF quantifies how well an imaging system transfers contrast at different spatial frequencies, representing the system's overall sharpness performance.