How to Choose the Right X-ray Collimator: Complete Selection Guide

The X-ray collimator, also known as the beam limiter or light beam diaphragm, controls the size and direction of the X-ray beam. It is essential for radiation safety and image quality. Choosing the wrong collimator can cause radiation leakage, poor image contrast and failed acceptance tests. Follow this guide to match the right collimator to your X-ray system.

Manual or motorized?

• Manual collimator — blades are adjusted with knobs. Simple structure, low failure rate, no control wiring. Best for mobile X-ray machines, U-arm systems, small clinics and veterinary X-ray equipment.
• Motorized collimator — motor-driven blades with remote control and optional PBL (automatic beam limiting) that matches the X-ray field to the detector. Best for fixed DR systems and high-volume hospital radiology departments.

Match the kV rating

Collimators are commonly available in 125 kV and 150 kV versions.

• Choose 125 kV for mobile and low-power systems.
• Choose 150 kV for high-power tubes used in chest and abdominal exams.
• Rule: the collimator kV rating must be equal to or higher than the maximum tube voltage.

Check the light field accuracy

• Industry standard: the light field must match the X-ray field within 2% of SID.
• LED light source is recommended — stable brightness and much longer service life than halogen lamps.
• For extremity exams, confirm the field can close down to a small size (e.g. 3 × 3 cm).

Verify the flange mount

• The flange size and mounting holes must match your tube housing. Different brands are not interchangeable — confirm the flange type before ordering.

Ask for compliance documents

• Require the IEC radiation safety test report, light-field accuracy test report, and CE/FDA documentation for export orders.

Quick selection summary

表格

Scenario	Recommended collimator
Mobile X-ray, U-arm, small clinic, veterinary	Manual, 125 kV, LED
Fixed DR, high-volume radiology	Motorized, 150 kV, optional PBL

Tip: never choose by price alone. Non-standard low-cost collimators often have poor light-field accuracy and thin lead blades, causing image scatter and radiation over-exposure.

Author:X Ray Collimator