A radiographic grid with a k-factor of 1 would offer no change in image contrast.

• A. Increased image contrast
• B. No change in image contrast
• C. Decreased image contrast
• D. Variable depending on grid ratio

Answer: (B)

Grids affect image contrast by reducing scatter that reaches the film, and the grid factor (k-factor) describes how the exposure must be adjusted when a grid is used. If the k-factor is 1, it means using the grid does not change the amount of exposure needed to produce the same film density as without the grid. In that case, the balance between primary photons and scattered photons reaching the receptor is unchanged, so the amount of scatter reaching the film—and thus the image contrast—remains the same. Therefore, there is no change in image contrast. In practice, grids usually alter exposure (k > 1) and improve contrast, but a k-factor of 1 implies no contrast change.