Veterinary Radiography: Grid Types, Functions, and Parameters

What is the primary purpose of using a grid in radiography?

To reduce scatter radiation reaching the film and improve image quality.

At what depth of solid tissue is the use of a grid recommended?

When the area to be radiographed is equal to or above 10cm, or 15cm for the chest.

What materials are used in the construction of a grid?

Thin strips of lead alternating with strips of radiolucent materials like plastic or aluminum, encased in aluminum.

What is the effect of using a grid on film fogging?

It reduces film fogging and improves image quality.

What are the two broad groups of grids?

Stationary grids and moving grids.

What is a parallel grid?

The simplest type of grid where the strips are vertical and parallel, which can lead to grid cut-off.

How does a focused grid differ from a parallel grid?

A focused grid has central strips that are vertical, with side strips sloping to account for beam divergence, preventing grid cut-off.

What is a pseudo-focused grid?

A grid that is intermediate in efficiency and price, with vertical strips that get progressively shorter towards the edges.

What is the advantage of crossed-hatch parallel grids?

They absorb more scatter radiation by having strips running in both directions at 90-degree angles.

What is the function of moving grids?

To eliminate visible parallel lines on the radiograph by oscillating during exposure.

What is the grid factor?

The increase in mAs required when using a grid, typically 2.5 to 3 times the original value.

How does the number of lines per centimeter affect grid performance?

More lines per centimeter result in finer grid lines and less disruption to the image.

What is the grid ratio?

The ratio of the height of the strips to the width of the radiolucent interspace, affecting efficiency and cost.

What problems can arise from improper use of a grid?

Issues like bending of lead strips, incorrect focal-film distance, or using the grid upside down can lead to image cut-off.

What happens if a grid is used back to front?

The primary beam will be absorbed on the edges, leading to an image with adequate exposure in the middle but varying densities at the edges.

What is the recommended grid ratio for practice grids?

Typically between 5:1 to 10:1, with more powerful machines using ratios up to 16:1.

What is the role of the Potter-Bucky diaphragm?

It is a mechanism that allows for the movement of the grid during exposure to eliminate grid lines.

Why is it important to follow the manufacturer's recommendations for grid use?

To ensure optimal performance and avoid issues like image cut-off or grid malfunction.