How does an increased grid ratio affect radiographic image contrast?

How does an increased grid ratio affect radiographic image contrast?

• A. Decreased Contrast
• B. Grid Ratio Does Not Affect Image Contrast
• C. Increased Contrast
• D. Increased Quantum Mottle

Answer: (D)

Raising grid ratio reduces scatter reaching the image receptor. With more lead absorption, the fog from scattered photons decreases, making the differences between dense and less dense tissues stand out more clearly, so image contrast improves. A higher grid ratio also means fewer primary photons reach the receptor, so exposure often needs to be increased to maintain brightness; if exposure isn’t increased, image noise (quantum mottle) can become more noticeable. The direct effect of higher grid ratio is improved contrast, while increased mottle is a potential consequence of not compensating exposure.

Raising grid ratio reduces scatter reaching the image receptor. With more lead absorption, the fog from scattered photons decreases, making the differences between dense and less dense tissues stand out more clearly, so image contrast improves. A higher grid ratio also means fewer primary photons reach the receptor, so exposure often needs to be increased to maintain brightness; if exposure isn’t increased, image noise (quantum mottle) can become more noticeable. The direct effect of higher grid ratio is improved contrast, while increased mottle is a potential consequence of not compensating exposure.