The new article addresses the aspects related to the accessories and components of diagnostic x-ray equipment, including the approach to be applied with respect to compatibility matters.

The Food and Drug Administration (FDA or the Agency), the US regulating authority in the sphere of healthcare products, has published a guidance document intended to provide additional recommendations and clarifications to be considered by assemblers of diagnostic x-ray equipment in order to ensure the safety and proper operations of such products. The document is non-binding in its legal nature, nor is intended to introduce new rules or impose new obligations. Moreover, the authority explicitly states that an alternative approach could be applied, provided it is in line with the current regulatory requirements and has been agreed with the authority in advance. 

The guidance is structured as a questions-and-answers document by the virtue of which the authority provides answers to the most important questions raised by the industry with respect to diagnostic x-ray devices. The scope of the guidance covers, inter alia, the aspects related to restrictions on the assembly of components. First of all, the authority states that the certification status of the components in a system influences the ability of an assembler to legally install additional components into an existing system. 

Applicable Requirements 

According to the guidance, the rules and requirements to be considered with respect to the assembly and reassembly of diagnostic x-ray equipment are set forth by the regulation 21 CFR 1020.30(d). The authority further emphasizes the following key points: 

  • A new system, consisting of all unused components, may only be assembled with all certified or all uncertified components. 
  • The entire system could consist of all uncertified components provided these components have never been used in an x-ray system. 
  • The system could be assembled from all the certified components provided they are compatible with each other (the said compatibility should be confirmed by the respective documentation). 
  • In the case of an existing system comprised of uncertified components being reassembled, new components could be either all certified or all uncertified. 
  • In case of a system containing at least one certified component being reassembled, all the replacement or additional components should be certified. 
  • Exchange of an uncertified component for an identical uncertified component or reinstallation of any component following repair of the component to its original condition is not considered assembly or reassembly for the purpose of the Performance Standards. 


Accessory Component 

The guidance describes in detail the concept of “accessory comment”, and also provides additional clarifications regarding the reporting obligations triggered by the installation of an accessory component. 

According to the applicable regulation, an accessory component stands for:

  • A component used with diagnostic x-ray systems…that is not necessary for the compliance of the system with applicable provisions…but which requires an initial determination of compatibility with the system, or
  • A component necessary for compliance of the system with applicable provisions of this subchapter but which may be interchanged with similar compatible components without affecting the system’s compliance, or 
  • A component compatible with all x-ray systems with which it may be used and that does not require compatibility or installation instructions. 

Under the general rule, in case the component being installed has been duly certified by its manufacturer, the reporting of such installation is not required. Furthermore, components covered by the scope of the first and second clauses above are not subject to reporting when used for another diagnostic x-ray system within the same healthcare institution. At the same time, a report will be required in case of a permanent relocation into a system placed at a new address. In such a case, the appropriate report of assembly will be required to verify compliance with the applicable regulatory requirements, as well as the instructions of the manufacturer. A slightly different approach should be applied with respect to components falling within the scope of the third category since they do not require assembly to be used – if this is confirmed by the instructions communicated by the manufacturer, the respective obligations on reporting and certification will not apply. 


Another important concept described in the guidance is “compatibility”. The authority acknowledges that diagnostic x-ray systems could be comprised of components manufactured by different medical device manufacturers and even at different times. In order to ensure their proper operations when being used together, as well as the overall safety and effectiveness of the system in general, all the manufacturers involved should provide a statement of compatibility. 

As further explained by the FDA, there are three definitions of compatibility that apply to diagnostic x-ray systems: 

  • Operational or Functional Compatibility – any combination of components could be interconnected, provided the operational functions of the system were not impaired to an extent objectionable to the user. It is important to mention that the above definition is different from the one introduced by the Performance Standards. The authority additionally emphasizes that it is no longer acceptable to rely on operational or functional compatibility only when installation involves certified components. 
  • Manufactured Specified Compatibility, which means that when compatible components are brought together following the manufacturer’s assembly and testing instructions, the finished subassembly or system will meet the requirements of the Performance Standards. The latter provides that it is the responsibility of the manufacturers of individual components or systems to specify the compatibility of certified components, otherwise the component will be deemed non-compatible.  The use of non-compatible components should be duly reflected in the assembler’s forms.  
  • Noncompatible. According to the guidance, any components that rely on the performance or characteristic(s) of other components for which no compatibility has been stated are considered to be non-compatible.

The authority also mentions that each time the concept is used in the guidance, it is presumed to refer to the manufacturer specified compatibility. 

As explained by the authority, it is not necessary for compatibility to be stated between any and all components of a system. Instead, compatibility statements are required of components manufacturers only when the interconnection or use together of those components depends on their compatibility. 

In summary, the present FDA guidance highlights certain specific aspects related to assembly. For instance, the document describes the approach to be applied when determining compatibility between the components of a diagnostic x-ray system and also describes the general principles to be followed in terms of components and accessories. 




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