Which grid type consists of two sets of parallel lead strips?

The grid type that consists of two sets of parallel lead strips is known as a crossed grid. This design allows for improved cleanup of scattered radiation by having one set of lead strips oriented in one direction, while the second set is oriented at a right angle to the first. The crossed grid configuration is particularly effective in minimizing scatter but requires precise alignment of the X-ray beam to the grid, as it cannot accommodate image misalignment in either direction.

In contrast, linear grids have only one set of lead strips aligned in parallel, which is simpler to use but not as effective in scatter reduction compared to crossed grids. Focused grids are designed to be used at specific distances and have strips that are angled to align with diverging X-ray beams, making them different from crossed grids. Non-focused grids feature parallel strips without consideration for the angle of the X-ray beam, which reduces their efficiency in scatter cleanup compared to focused or crossed grids.