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Using 3D printer to recreate bones

SASchaffer

Plastic
Joined
Feb 16, 2016
Hello- I have a good friend who is a forensic anthropologist. Ever seen the TV show 'Bones?' That what she does- helps identify people by analyzing their bones. We have been discussing using a 3D printer to reproduce bones from blue-light scans. If we work this process out, it can allow her to 'send'/'receive' samples to/from colleagues all over the world. It's a really cool idea- if it is accurate enough.
My interest is in the metrological error and the printing error that will be present in the process.
If you consider the bone's original surface as the basic surface (nominal), what kind of profile tolerance can I expect from 3D printed parts? Anyone doing anything like this?
Thanks for your comments!
 
Hundreds, if not thousands of people are already doing this (if we're counting the medical community around the globe) for surgical anatomical topography. What tolerance depends on the geometry and the mechanical properties of the mat'l.
 
A Stratasys uPrint SE plus will be better than .005" on a bone OD say. In FDM printing with good printers, small features can be a little distorted as you get down towards the resolution of the extrusion, but the diameter of a 2" cylinder for example is remarkably accurate. The limitation is the resolution of the scan process. We segment from CT data so the limitation is usually the layer spacing in CT, typically with slices every 1mm and the surface is interpolated from these. These are off live patients, there are research CTs that are way higher resolution and as they say in forensic radiology, the dead don't have dose limits (higher scan energy = more radiation = better resolution). N.B. CT followed by segmenting with freeware like inVesalius is way less hassle than 3D scanning if you are in an institution that has a research CT. The key is that current resolution is way better than surgeons or radiologist we've worked with would worry about for planning a cancer tumour excision for example. I'd say for bones, and we've done a lot of them, you really want a printer with support material since there's a lot of complex geometry. Tibias and such are maybe OK but skulls, particularly the sinus detail, would be a nightmare without support material.

I think this field needs to define carefully what is needed. How much can you learn from printing bones, were you lose fine detail in the scan, and are there situations where printing the soft tissue as well would be useful This is where a lot of clinical printing wants to go. The holy grail for surgical planning right now would be to do one print with bone that behaved like bone - hard like ABS but brittle for drilling, and then in the same model print one or more types of soft tissue, that feels like brain, and then tumour, for example or at least is a different colour.
 
@rcoope:
Thank you. Your last paragraph is what we are looking to explore. How 'barebones' (see what I did there? :)) can a research unit get with their scanner and printer and still be able to have useful results. What do you use your printing for? What industry are you in?
 
We're a biomedical research facility embedded within a couple of big city hospitals and connected to the university. We're doing some surgical planning models and some bone guides for cutting up fibulas for jaw reconstructions. All clinical research projects so covered under ethics etc but done on actual cases. Nothing requiring fine resolution; surgeons need it to be millimeter precision not .05mm. In what you're proposing I'd be worried about missing small details like scratches or other mechanical damage unless you have extremely high resolution.

One area of interest in general is creating very large digital data sets and using machine learning to correlate them with other data. We had a meeting this very morning on how MRI brain tumour data could be analyzed for correlations with genomic information fed back into the machine learning algorithm to see if you could predict the genomic status from the MRI view of a tumour. People likewise are doing this with pathology slide scans and pretty much everything else that produces images. There might be some interesting things you could do with a large set of 3D models of bones for which there was also other information such as pathology analysis. It would be more of an imaging project than a 3D printing project though.

There's a guy at the University of Washington who is doing CTs of all of the different fish in the sea (ideally). Lots of interesting digital skeleton pics get put up on twitter.
 








 
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