What material is NOT typically used for interspace in grids?

In the context of grids used in radiography, the interspace material plays a crucial role in reducing scatter radiation while allowing primary radiation to pass through. Each material chosen for interspacing has specific properties that contribute to the grid's effectiveness.

Lead is not utilized as an interspace material primarily due to its high density and tendency to absorb significant amounts of primary radiation, which undermines the grid's purpose. If lead were used as the interspace material, it would create more attenuation of the useful X-ray beam, thus reducing the image quality rather than enhancing it. A grid needs interspaces that provide a pathway for primary radiation while effectively absorbing scatter, and lead fails to serve that role effectively.

In contrast, materials such as aluminum are lightweight and allow for the passage of primary radiation while still being effective at reducing scatter. Air is also used in some grid designs as it is non-obstructive to the X-ray beam. Wood can be employed as an interspace material in specific grid designs, though it is less common today due to durability concerns compared to metals and plastics. Hence, these other materials are selected specifically for their ability to support the grid's function without interfering with the desired radiation characteristics.