Which type of grid is designed for specific source-to-image distance (SID) ranges?

The focused grid is specifically designed to be most effective for certain source-to-image distance (SID) ranges. This type of grid is constructed with lead strips that are angled so that the primary x-ray beam is properly aligned with the lead strips as it passes through. This alignment minimizes the amount of scatter radiation that reaches the image receptor, enhancing image quality.

The design of the focused grid allows it to function optimally at a designated SID by ensuring that the x-rays that strike the grid parallel to its lead strips are the ones that will create the best image quality. Outside of that specific SID range, image quality can degrade, or the grid may cause increased exposure to the patient due to unnecessary absorption of the primary beam. This makes focused grids particularly suited for specific techniques and imaging protocols where controlling scatter is crucial.

Other options present valid types of grids but do not adhere to the specific SID requirement:

• The crossed grid consists of two sets of lead strips positioned at right angles to each other and is designed to capture scatter more effectively in multiple directions but does not have an SID-specific design.

• The parallel grid has lead strips arranged parallel to each other, which means it can be used over a wide SID range but is less efficient in reducing scatter compared to a