The new article clarifies the requirements pertaining to the date of manufacture and also highlights the measurement-related matters.
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.
In particular, the document provides guidance on determining the “date of manufacture” for diagnostic x-ray equipment and outlines specific measurement requirements under the relevant performance standards. These requirements are vitally important for ensuring compliance with regulatory standards and ensuring equipment safety.
All the information is provided in a format of questions and answers in order to assist the parties involved in understanding the relevant regulatory requirements and the way they should be followed.
Date of Manufacture
Question: How does a manufacturer determine if their system must comply with updated standards?
Answer: Compliance with updated performance standards depends on the date of manufacture:
- A system certified on or after June 10, 2006, must comply with updated standards.
- If all certified components of a system were manufactured on or after June 10, 2006, the system must comply.
- Replacing a single component in a pre-2006 system does not require the entire system to meet updated standards. However, the new component must comply with standards applicable at its manufacturing date.
Examples:
- Example 1: A 2007 air kerma display replacing a 2005 display in a fluoroscopic system must meet 2007 standards, but the system as a whole does not need to comply with post-2006 updates.
- Example 2: A 2007 fluoroscopic system incorporating a 2005 air kerma display must meet post-2006 standards for the system, even if the display predates these standards.
For CT systems, the date of manufacture is defined as the manufacturing date of the CT gantry (21 CFR 1020.30(a)(3)).
Impact of Relocation:
Question: Does relocating and reassembling a system change its date of manufacture?
Answer: No. A system retains its original date(s) of manufacture even if disassembled and reassembled at a new location.
For more information, manufacturers are encouraged to refer to the Assembler’s Guide to Diagnostic X-Ray Equipment developed by the authority.
Measurements
The scope of the document also covers the aspects related to measurements in the context of x-ray devices.
Test Programs for Quality Control:
Question: Must manufacturers use test programs exactly as described in the regulations?
Answer: Manufacturers must generally follow test programs described in the regulations. However:
- Alternate test procedures may be proposed via a written application (21 CFR 1010.13).
- FDA accepts validated alternate procedures if they ensure compliance. Manufacturers must document and justify alternate methods in their quality control records (21 CFR 1002.30(a)(2)).
Rounding Test Results:
Question: Can test results slightly exceeding limits be rounded to fall within compliance?
Answer: No. Regulatory limits are absolute and cannot be exceeded. Manufacturers should set stricter internal action limits to ensure compliance.
Example: If a maximum air kerma rate is measured at 88.1 mGy/min and the limit is 88 mGy/min, the system is non-compliant.
Measurement Criteria for Technique Factors:
Question: What does “measurement criteria” mean regarding technique factors?
Answer: Measurement criteria define how technique factors like peak tube potential and tube current are determined. Manufacturers must provide specific measurement criteria in their documentation for meaningful comparisons (21 CFR 1020.30(h)(3)(viii)).
Example: Exposure time measurement for three-phase equipment may vary between manufacturers and must be clearly defined.
Linearity Requirements:
Question: Does the linearity requirement apply to the system as a whole or individual components?
Answer: The linearity requirement applies to the x-ray system as a whole. Testing is limited by the manufacturer’s rating of the system’s limiting component (21 CFR 1020.31(c)).
Leakage Radiation Measurement:
Question: Can the main beam be blocked during leakage measurement?
Answer: Yes. Radiation passing through the beam-limiting device aperture is not considered leakage radiation and can be blocked at the exit to measure leakage from the diagnostic source assembly (21 CFR 1020.30(b)).
Conclusion
In summary, the document emphasizes the following key points:
- Date of Manufacture: Defines compliance with updated standards. Changes in system location or repairs do not affect the original manufacturing date.
- Measurements: Manufacturers must follow or validate test procedures, ensure results meet absolute regulatory limits and define criteria for technique factors. Leakage measurements and linearity requirements apply system-wide with specific considerations.
The guidance provides additional clarifications to be followed in order to ensure that manufacturers and assemblers maintain compliance with FDA standards, fostering the safe and effective use of diagnostic x-ray equipment.
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