Grid selectivity is defined as the ratio of primary radiation transmitted through the grid to secondary radiation transmitted through the grid.

Grid selectivity is defined as the ratio of primary radiation transmitted through the grid to secondary radiation transmitted through the grid.

• A. The ratio of primary radiation transmitted through the grid to secondary radiation transmitted through the grid
• B. The ratio of primary to scattered radiation transmitted through the grid
• C. The ratio of transmitted photons to absorbed photons in the grid
• D. The ratio of grid thickness to interspace width

Answer: (A)

Grid selectivity shows how well a grid discriminates between the useful primary photons and the unwanted scatter that pass through it. It’s defined as the ratio of primary radiation transmitted through the grid to secondary (scatter) radiation transmitted through the grid. When a grid allows more primary photons to reach the image receptor while absorbing most of the scattered photons, this ratio is high, leading to better image contrast. The concept highlights why grids are used: to reduce scatter reaching the image receptor without excessively attenuating the primary beam. In practice, increasing grid ratio or proper alignment tends to improve selectivity because more scatter is absorbed relative to primary transmission, though overall primary transmission may drop and require exposure adjustments.

Grid selectivity shows how well a grid discriminates between the useful primary photons and the unwanted scatter that pass through it. It’s defined as the ratio of primary radiation transmitted through the grid to secondary (scatter) radiation transmitted through the grid. When a grid allows more primary photons to reach the image receptor while absorbing most of the scattered photons, this ratio is high, leading to better image contrast. The concept highlights why grids are used: to reduce scatter reaching the image receptor without excessively attenuating the primary beam. In practice, increasing grid ratio or proper alignment tends to improve selectivity because more scatter is absorbed relative to primary transmission, though overall primary transmission may drop and require exposure adjustments.