How does an increased grid ratio affect radiographic image contrast?

How does an increased grid ratio affect radiographic image contrast?

• A. Decreased contrast
• B. Increased contrast
• C. No change
• D. Increased noise

Answer: (B)

Increasing the grid ratio makes the grid more effective at absorbing scattered photons produced in the patient. Scatter adds a gray haze to the image and washes out the differences between light and dark areas. By blocking more of this scatter, a higher grid ratio reduces fog and enhances the true differences in attenuation, so contrast improves. Therefore, image contrast increases with a higher grid ratio. The other options don’t fit because they imply no improvement or a different issue; while a grid can require more exposure to maintain density (and thus can affect noise if not compensated), the primary effect on contrast is its scatter-killing action that sharpens the image.

Increasing the grid ratio makes the grid more effective at absorbing scattered photons produced in the patient. Scatter adds a gray haze to the image and washes out the differences between light and dark areas. By blocking more of this scatter, a higher grid ratio reduces fog and enhances the true differences in attenuation, so contrast improves. Therefore, image contrast increases with a higher grid ratio. The other options don’t fit because they imply no improvement or a different issue; while a grid can require more exposure to maintain density (and thus can affect noise if not compensated), the primary effect on contrast is its scatter-killing action that sharpens the image.