How to Measure Focal Spot Size Using a DR Panel – Quick Guide!

31 Jul.,2025

Measuring the focal spot size of an X-ray tube using a digital radiography (DR) panel. By employing a slit in conjunction with the DR detector and applying geometric magnification calculations, operators can accurately determine the actual focal spot dimensions. The step-by-step procedure details experimental setup, image acquisition, and data analysis.

 

Ever wondered how to accurately measure the focal spot size  of your X-ray tube using a DR (Digital Radiography) panel? Here's a simple method to do it!  

What You'll Need:
✔ DR panel (flat-panel detector)  
✔ X-ray machine  
✔ slit (for precise measurement)
✔ Software measurement tools

Steps:
1. Set Up the Slit
   - Place a small slit in front of the X-ray tube.  
   - Ensure it's perpendicular to the beam.  

2. Position the DR Panel
   - Place the DR panel at a known distance from the focal spot.  

3. Take an Exposure
   - Use low mA/s to avoid saturation.  
   - The image will show a magnified blur representing the focal spot.  

4. Measure the Blur Width
   - Use imaging software to measure the FWHM (Full Width at Half Maximum) of the blurred edge.  

5. Verify with Standards
   - Compare results with manufacturer specs.  

Why This Matters:
✅ Ensures image sharpness and system performance.  
✅ Helps in QC (Quality Control) and compliance testing.  

Have you tried this method? Any tips or alternative techniques? Share below!