FDA Guidance on Radiation Control Regulations: Models and Assembly Requirements

Table of content

The Food and Drug Administration (FDA or the Agency), the US regulating authority in the sphere of healthcare products, has published a guidance document dedicated to radiation control regulations. The document is intended to provide additional clarification and recommendations to be taken into consideration by manufacturers of diagnostic X-ray equipment and other parties involved in order to ensure compliance with the regulatory requirements set forth under the existing legal framework. 

At the same time, provisions of the guidance are non-binding in their legal nature, nor are they intended to introduce new rules or impose new obligations. Moreover, the authority explicitly states that an alternative approach could be applied, provided such an approach is in line with the relevant legislation and has been agreed with the authority in advance.

Accidental Radiation Occurrence (ARO)

The guidance, structured as a questions-and-answers document, provides important clarifications regarding the radiation-related incidents and the way they should be handled by the parties involved. 

Applicability of Reporting Requirements:

Question: Do ARO reporting requirements apply to foreign manufacturers?  

Answer: Yes, foreign manufacturers selling products in the U.S. must comply with ARO reporting requirements outlined in 21 CFR 1002.20.

Events Qualifying as AROs:

Question: Are rescans or restarts considered AROs?  

Answer: No, operator-initiated rescans, or restarts are not AROs. However, the following events must be reported as AROs:

• Radiation emitted without a valid operator command.
• Radiation emitted at incorrect technique factors.
• Radiation that does not cease upon command.

Thresholds for Reporting AROs:

Question: Is there a lower radiation emission threshold below which an ARO is not reportable?  

Answer: Any accidental radiation exposure must be reported unless:

• The leakage radiation from components stays within limits defined in 21 CFR 1020.30(k) and 1020.30(l).
• The exposure results from acceptable manufacturing, testing, or usage standards.

Events exceeding these limits must be reported, and the system may be deemed defective.

Records and Defects

The scope of the document also covers the aspects related to record-keeping requirements, as well as defects and regulatory approaches should they be subject to.

Question: Where should manufacturers maintain quality control and test result records?  

Answer: Manufacturers, including foreign entities, must maintain records at their facilities. These records must be accessible during FDA inspections and adhere to 21 CFR 1002.30(a).

Definition and Examples of Defects:

Question: What qualifies as a defect under 21 CFR 1003.2(b)?  

Answer: A defect is defined as a failure relating to the emission of electronic product radiation due to design, production, or assembly. Examples include:

• X-ray systems failing to emit radiation as intended during procedures.
• Components emitting radiation not conforming to design specifications.
• Systems requiring retakes due to radiation-related failures, causing unnecessary patient exposure.

Examples:

1. X-Ray Tube Failure Mid-Procedure: A defect exists if this failure leads to excess radiation or disrupts an interventional procedure.
2. Premature Tube Burnout: If caused by design, production, or assembly issues, it qualifies as a defect.

Question: Are failures unrelated to radiation (e.g., broken wheels) considered defects?  

Answer: No. Failures not affecting the emission of radiation, such as mechanical issues, are not considered defects under 21 CFR 1003.2(b).

Question: Are image artifacts considered defects?  

Answer: Not typically. Artifacts caused by patient motion, dense objects, or CT reconstruction are not defects. However, artifacts resulting from unexpected device movement during radiation exposure due to design, production, or assembly issues indicate a defect.

Question: Does a large focal spot size constitute a defect?  

Answer: Yes, if the focal spot exceeds specifications at the time of sale. If the issue arises from normal wear, misuse, or age, it may not qualify as a defect unless radiation exceeds acceptable leakage limits.

Corrective Actions

Question: Can manufacturers correct noncompliant systems while notifying the FDA?  

Answer: Yes. Manufacturers can begin corrective actions concurrent with FDA notification but must ensure these actions resolve the defect. If corrections fail, additional actions may be required under 21 CFR 1004.2 and 1004.6.

FDA Procedures Upon Defect Discovery:

When the FDA identifies a defect or noncompliance:

1. The manufacturer is notified in writing, including test results, defect details, and evidence supporting FDA’s findings (21 CFR 1003.11).
2. The manufacturer is given a reasonable timeframe to respond with evidence disputing the defect or noncompliance (21 CFR 1003.11(a)(3)).

If the defect is confirmed, manufacturers must:

• Notify affected users and the FDA (21 CFR 1003.10(b)).
• Repair, replace, or refund the cost of defective systems (21 CFR 1004.1).

Conclusion

In summary, the guidance emphasizes stringent oversight for AROs, defects, and record-keeping in diagnostic x-ray systems:

• ARO Reporting: All accidental exposures, except for specified exclusions, must be reported.  
• Record Maintenance: Quality control records must be accessible during inspections.  
• Defects: Failures caused by design, production, or assembly that compromise radiation safety or functionality qualify as defects.  
• Corrective Actions: Manufacturers must act promptly to address defects while maintaining regulatory compliance.

These guidelines are intended to ensure patient safety and the integrity of diagnostic x-ray systems in the U.S. market.

Source

https://www.fda.gov/media/119827/download

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