CAMRT Radiography Practice Exam

What is the focusing range for a low grid ratio?

1. Larger focusing range

2. Smaller focusing range

3. No change in focusing range

4. Variable depending on equipment

The correct answer is: Larger focusing range

The correct answer is that a low grid ratio has a larger focusing range. Low grid ratios are designed to allow greater flexibility in terms of how far the imaging receptor can be positioned from the grid while still effectively reducing scatter radiation. This smaller degree of attenuation of scattered radiation offers a wider range for positioning the elements involved in imaging—essentially making it easier to align the x-ray beam and the detector without losing significant image quality. In contrast, higher grid ratios tend to narrow the focusing range because they require a more precise positioning to effectively clean up scatter, thus allowing less margin for error in alignment. The emphasis on precise alignment in high-ratio grids can lead to a more limited effective range, making low grid ratio systems advantageous for a variety of clinical settings where flexibility might be necessary.