Re: Medical RP Discussion

From: Ulrich Kliegis (Ulrich.Kliegis@kiel.netsurf.de)
Date: Tue Oct 08 1996 - 22:34:10 EEST


Alair Griffin wrote:
>
> We have taken MRI scan data, converted it using in-house proprietary
> software (and no it is not Materialize), produced the .STL file and
> built the RP part in ABS plastic on our FDM.

Are you aware that MRI is not suited for producing bone models? MRI
images do not represent the anatomy in a linear way. Distortions in
all three axes which are hardly, if ever correctable (several percent
of the image diagonal!) are caused by the physical imperfections,
mainly of the scanned object itself. Conducting structures like
vessels and isolating objects like bone lead to severe deviations of
the slice image from the assumed real anatomy. Never use MRI to
produce a prosthesis!

For bone, nothing but CT is the method to record the patient's
anatomy.

>
> We have taken a series of mostly wrist files and produced some
> really nice parts.

They may look nice, but did you assess the accuracy?

We have demonstrated the turn-around time to a
> group of radiologists. Basically, they FTPed the files on Friday,
> we did the scan conversion on Saturday, we built the part on Sunday,
> and delivered it to the radiologists on Monday.

We are able to turn CT data sets into models overnight. Verbally.
Using CNC milling of polyurethane foam. SL models take 12 hours more.
But only if demanded, and if every part of the gear works as specified.

>
> Issues for this type of RP service:
>
> I agree with the comment that was made about this kind of service
> requiring that the service bureau have staff with medical
> background. Insurance liability issues are a real concern also. Has
> anyone priced liability for the medical side of RP? I have, and it
> is pretty expensive.

At least if you do business in the US or Canada. But an established
quality management system is mandatory for this kind of business, no
matter where you are. The best QMS, however, does not help if the
medical knowledge lacks.

>
> Another problem facing medical RP relates to the RP processes. I
> don't feel that there is only one RP technique that I would use for
> medical RP. I feel that one needs a variety of processes to truly
> serve a future medical RP market.

I agree fully.

Cheers,

Ulli
----------------------------------------------------------
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Ulrich.Kliegis@kiel.netsurf.de
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Ulrich G. Kliegis Phone: +49 431 331144 Fax: +49 431 331146



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