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PACS - interpreting MDD and Borderline Guidance


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Classification of PACS has been covered from different angles in various posts. However I haven't found specifically what will help resolve a classification issue I'm having.

We have a PACS stand-alone software device used as a non-primary diagnostic aid for dental applications. We are in the early stages of CE marking this device. Using the MDD 93-42, Borderline Classification Guidance, and several other informal resources, we're not coming to a clear consensus on classification.

When evaluating the device per MDD Annex 9 Section 3, all rules leave the device as Class I (ie Rule 10 mentions "direct diagnosis of vital physiological processes.." where our device isn't a direct means to diagnosis nor are physiological conditions considered vital).

Going up to Annex 9 Section 2 (Implementing Rules), 2.3 states "Software, which drives a device or influences the use of a device, falls automatically in the same class." Our software connects to class iia and iib scanners, but does it "drive or influence" them?

This is where I get confused on the intention of the rule. Our software 1) displays the status of the scanner during acquisition, with all status information going from scanner -> software. 2) Upon starting acquisition, our software gives the "green light" to the scanner to initiate it's own acquisition protocol/parameters to complete the exam. Our device does not set any scanner parameters or directly turn it on or off; scanner must be prepared independently prior to acquisition. Where does this put us with "drive" or "influence"?

Now, looking at Borderline Classification Guidance, 8.4 (PACS) c(iii) states, "Standalone software, e.g. software which is used for image enhancement is regarded as driving or influencing the use of a device and so falls automatically into the same class. Other standalone software, which is not regarded as driving or influencing the use of a device, is classified in its own right". Our software DOES allow for the enhancement of images in a post-process fashion; again not setting scanner parameters such as exposure (risk associated with duration of radiation). I don't see where the added risk (bump in classification) is in this manner of image enhancement, as all raw images are displayed in the software as well. So, I'm not sure we meet the intention of this rule.

The Competent Authority we've just started speaking with claims that the "green light" we give to a 3rd party scanner "indicates that this software can control Extraoral X-ray units"

I would appreciate any input on this, as interpretation of these points has a huge impact on a small, low-risk device manufacturer. Thanks!


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We also manufacture software that falls under the PACS portion of the Borderline Manual. What kind of post-processing functions does your product allow? Also, is the "green light" required for the other unit to proceed with acquisition?


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Our device can sharpen, contrast, perio and endo filters, rotate, flip, invert, colorize, grayscale and emboss, and various combinations of basic adjustments - all while having the original image from the scanner available to easily switch back to.
On all extra oral 2b scanners, our "green light" isn't needed. Also, any images can be imported into the software free of 3rd party device pairing. The "green light" is needed for intraoral (2a) sensors in some cases.


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You mention a couple filtering functions, though I am unfamiliar with those specific types. Take a look at 8.4(b)'s language and see if that seems applicable:
(b) Where the post-processing of the image for diagnostic purposes is such as:
- image processing functions which alter the image data (e.g. filtering, multiplanar reconstruction, 3D reconstruction)
- complex quantitative functions (e.g. arterial stenosis evaluation, ventricular volume calculation, calcium scoring, automatic indication (detection) of potential lesions
If so, in related the Outcome section you may find your answer (emphasis mine):
(ii) Those types of PACS (b) which drive a device or influence the use of a source device fall automatically in the same class in accordance with implementing rule 2.3, which classifies them as Class IIa or IIb. If this type of PACS does not drive or influence the use of the source device, this type of PACS can be classified under rule 10 if such PACS are intended to allow direct diagnosis, classifying them as Class IIa.


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Thanks for your response.
I think the bottom line is determining the drive/influence applicability.
With our enhancement tools, we do meet the description you provide from the Borderline Guidance 8.4(b). I'm not sure what this guidance is concluding from meeting this definition of PACS type. It's unclear if you're directed to Outcome (ii) from this? If so, we're back to drive/influence interpretation.
I can make the argument for Rule 10 not applying, as our device is not intended for "direct diagnosis of vital physiological processes". It IS indicated as a diagnostic device, but explained further in the IFU to what end.


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Help me understand what you mean by 'The "green light" is needed for intraoral (2a) sensors in some cases.' In what way are the sensors dependent on it?
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