Chapter 14 Scatter Control & Beam Restriction Flashcards
What is the purpose of an x-ray grid?
To absorb scatter radiation and improve image contrast.
What is the grid ratio formula?
Grid ratio = height of lead strips / distance between them.
Higher grid ratios result in better image contrast but require what?
Higher patient dose to compensate for x-ray absorption.
What is the purpose of grid frequency?
To describe the number of lead strips per inch or cm in a grid.
What effect does air-gap technique have on scatter radiation?
Reduces scatter, improving contrast without a grid.
What is the primary disadvantage of using grids?
Increased patient dose.
What type of grid pattern is most effective at scatter reduction?
Cross-hatched grid.
What happens if a focused grid is improperly aligned?
Grid cutoff, causing underexposed image areas.
What is the function of a Bucky grid?
Moves the grid during exposure to blur grid lines.
How does higher kVp affect scatter radiation?
Increases scatter, requiring a grid for contrast improvement.
What is the purpose of beam restrictors like collimators?
To limit the x-ray field size, reducing scatter radiation.
What is a penumbra in x-ray imaging?
The blurred edge of an image caused by x-ray beam divergence.
What does contrast improvement factor (K) measure?
The effectiveness of a grid at improving contrast.
What type of grid cutoff occurs when the grid is angled?
Off-level grid cutoff.
What is the primary function of automatic exposure control (AEC)?
To automatically terminate exposure when the correct amount of radiation is received.
What happens when SID is too short with a focused grid?
Grid cutoff occurs.
What are the two main types of beam restrictors?
- Collimators
- Aperture diaphragms
Why is scatter control important?
It improves image contrast and reduces radiation dose.
What grid ratio is best for low kVp techniques?
Low-ratio grids (e.g., 5:1 or 6:1).
What is the main function of a variable aperture collimator?
It allows the adjustment of x-ray field size to reduce patient dose.
