Enforcement Policy for Positive-Beam Limitation Requirements in Diagnostic X-Ray Systems
This guidance outlines the enforcement policy for Positive-Beam Limitation (PBL) requirements in diagnostic X-ray systems following the May 3, 1993 amendment to the Performance Standard. The amendment allows assemblers to install manual beam-limiting devices (BLD) in stationary, general-purpose radiographic x-ray (GP) systems, eliminating the mandatory PBL requirement while maintaining PBL requirements for systems equipped with it.
Recommended Actions
- Update testing procedures based on system configuration (with/without table, PBL/manual BLD)
- Document any user modifications to PBL systems
- Implement proper testing methods for maximum EER measurements with large field image intensifiers
- Consider field coverage limitations when testing systems with small target angle X-ray tubes
- Maintain records of installation dates and system modifications
- Ensure compliance with applicable Performance Standard requirements for systems equipped with PBL
- Train testing personnel on the updated requirements and procedures
Key Considerations
Non-clinical testing
- Routine testing of GP systems with x-ray table should continue using Abovetable X-Ray Source Radiographic Systems (AR) test procedure
- For GP systems without table and equipped with manual BLD, use Vertical Cassette Radiographic Systems (VC) test procedure
- For GP systems without table but equipped with PBL, use Chiropractic Supplement to the AR procedure (ARB)
- Verify PBL mode functionality at installation and during testing
Safety
- PBL systems must prevent exposure until proper collimation is achieved
- PBL must operate correctly at designated source-image receptor distances (SID)
- Users can modify systems under 21 CFR 1020.30(q)(2) if modifications don’t result in non-compliance
Other considerations
- Maximum Entrance Exposure Rate (EER) measurements must be properly conducted for large field image intensifiers
- Special considerations apply for small target angle X-ray tubes regarding field coverage limitations
Relevant Guidances
- Radiation Control Requirements and Interpretations for Diagnostic X-ray Equipment
- X-Ray Equipment Performance Standards and Radiation Safety Requirements
- Safety and Performance Requirements for Cabinet X-ray Security Screening and Industrial Quality Control Systems
- Harmonization of Performance Standards for Diagnostic X-Ray Imaging Systems and Components with IEC Standards
- Performance Standards for Diagnostic X-Ray Systems and Major Components
Related references and norms
- 21 CFR 1020.31(g): Performance Standard for Diagnostic X-Ray Systems and Their Major Components
- 21 CFR 1020.30(q)(2): Modifications by system owners
Original guidance
- Enforcement Policy for Positive-Beam Limitation Requirements in Diagnostic X-Ray Systems
- HTML / PDF
- Issue date: 1993-10-13
- Last changed date: 2020-03-17
- Status: FINAL
- Official FDA topics: Medical Devices, Radiation-Emitting Products, Postmarket, Investigation & Enforcement
- ReguVirta summary file ID: 13de13b96f0d69900fe33542aa95c115
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