Bushong reading Ch 11 Flashcards
Contrast arises from what areas?
Light, dark and shades of gray on the x-ray image
What are the two principal characteristics of any image?
Spatial resolution and contrast resolution
Collimation improves…
Image contrast and reduces patient dose
What does reduced image contrast result from?
Scatter radiation
Grids with high frequency show…
Less distinct lines on images
What is the single largest factor in poor image quality?
Scatter radiation
What is the principal function of a grid?
To improve image contrast
What is the simplest type of grid?
Parallel
What is grid cutoff?
The undesired absorption of primary x-rays by the grid
What is the main disadvantage of parallel and crossed grids?
Grid cutoff
What type of grid is fabricated so that grid strips are parallel to the primary x-ray path across the entire image receptor?
Focussed grid
High ratio grids have less positioning __________ than low ratio grids
Latitude
What will happen if a grid is installed incorrectly and moves in the same direction as the grid strips?
Grid lines will appear
Greater positioning latitude is possible with what type of ratio grids?
Low ratio grids
The use of a moving grid instead of a stationary grid requires how much more patient dose?
15%
