Which statement about grids is true?

• A. They increase patient dose while decreasing scatter
• B. They have no effect on image quality
• C. They reduce scatter but increase patient dose
• D. They replace the need for collimation

Answer: (C)

Grids work by absorbing scattered photons inside the patient so they don’t reach the image receptor, which improves image contrast and overall image quality. However, they also attenuate part of the primary beam, so to maintain the same receptor exposure you must increase the exposure factors, which raises the patient dose. So grids reduce scatter and improve contrast, but at the cost of higher patient dose. They do not replace collimation, and they do have an effect on image quality, which is why this statement is the best fit.