1. What is Grid Ratio?

The grid ratio is a fundamental parameter in radiology that describes the relationship between the height of the lead strips (h) and the distance between them (d) in an anti-scatter grid. It's a unitless value that affects the grid's performance in improving image contrast.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( h \) — Height of lead strips (mm)
• \( d \) — Width of interspace between lead strips (mm)

Explanation: The ratio determines how effectively the grid removes scattered radiation while allowing primary radiation to pass through.

3. Importance of Grid Ratio

Details: Grid ratio affects image contrast and patient dose. Higher ratios provide better scatter rejection but require higher exposure factors. Typical ratios range from 5:1 to 16:1 in medical imaging.

4. Using the Calculator

Tips: Enter the lead height (h) and interspace width (d) in millimeters. Both values must be positive numbers. The calculator will compute the ratio which is unitless.

5. Frequently Asked Questions (FAQ)

Q1: What are typical grid ratio values in radiography?
A: Common ratios are 5:1, 6:1, 8:1, 10:1, 12:1, and 16:1, with higher ratios used for higher energy applications.

Q2: How does grid ratio affect image quality?
A: Higher ratios improve contrast by better scatter rejection but may increase image noise and require higher patient dose.

Q3: What's the relationship between grid ratio and Bucky factor?
A: Higher grid ratios typically have higher Bucky factors (ratio of total to primary radiation), requiring increased exposure.

Q4: When would you use a low ratio grid?
A: Low ratio grids (5:1-8:1) are used in mobile radiography or pediatric imaging where dose is a concern.

Q5: How does grid ratio relate to grid frequency?
A: Grid frequency (lines/cm) is independent of ratio. A grid can have high frequency but low ratio or vice versa.