What is the purpose of using a grid with a higher grid ratio?

• A. To decrease patient dose
• B. To reduce exposure time
• C. To improve image contrast by absorbing more scattered radiation; requires higher exposure to maintain receptor exposure
• D. To simplify alignment

Answer: (C)

Using a grid helps remove scattered photons before they reach the image receptor, which improves image contrast. A higher grid ratio means there are more lead strips relative to the interspace, so even more scatter is absorbed. This gives a cleaner, higher-contrast image. But the grid also attenuates some of the primary beam, so to keep the receptor exposure the same you must increase the exposure (more mAs or adjusted technique). That means patient dose tends to increase with higher grid ratios. It doesn’t inherently shorten exposure time, and higher-ratio grids require careful centering to avoid grid cutoff, so they don’t simplify alignment.