Which condition increases the signal-to-noise ratio in radiography?

• A. Scatter is present
• B. Excessive kilovoltage peak (kVp) is used
• C. Radiographic grids are utilized
• D. Patient receives an optimal radiation dose

Answer: (C)

Reducing scatter improves the signal-to-noise ratio. A radiographic grid absorbs much of the scattered photons produced inside the patient, so far fewer of these unwanted photons reach the image receptor. That means the useful signal—the primary photons that carry actual image information—becomes clearer relative to the background noise, raising the SNR and improving image contrast. If scatter is present, it adds fog to the image and lowers SNR. Using too high kVp can increase scatter and reduce contrast, which also harms SNR. While aiming for an appropriate dose helps overall image quality, the direct way to boost SNR among these options is to use a radiographic grid, keeping in mind that exposure often needs adjustment to compensate for the grid’s attenuation.