To avoid absorption of the remnant X-ray beam by lead strips within a grid cassette, how should the central ray be angled?

Angling the central ray along the long axis of the grid is the optimal approach because it aligns the beam with the orientation of the lead strips within the grid. Grids are designed to absorb scatter to improve image contrast, and their lead strips typically run in a specific direction. When the central ray is angled along this direction, it minimizes the likelihood of the remnant X-ray beam being absorbed by the lead strips, ensuring that as much of the beam passes through as possible. This technique enhances the overall image quality by allowing more diagnostic information to reach the image receptor while reducing artifacts that could arise from improper angling.

When the central ray is not aligned properly—such as angling it perpendicular or along the short axis of the grid—it can lead to significant absorption of X-rays by the grid, resulting in a reduction of the density of the image and possibly causing grid cutoff. Therefore, angling along the long axis is crucial for maintaining image quality and ensuring an adequate representation of the anatomical structures being examined.