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mikefazz last won the day on March 12

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About mikefazz

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  • Birthday 07/28/1980

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  1. I've looked a little into FDA approved materials and am interested in what it takes for a material to be considered safe for surgical guides. The dental material above adheres to the following: EN-ISO 10993-1:2009/AC:2010, EN-ISO 20795-1:2013, EN-ISO 7405:2009/A1:2013 The material guidel!ne from taulman3d (http://taulman3d.com/guidelne-spec.html) meets: ISO 11607-1: 2006, ISO 10993, USP Class VI, USP <661>, DMF (Drug Master File) number 16525 Taulman3d also has nylon 680 (http://taulman3d.com/nylon-680-spec.html) CAS Reg. No. 51995-62-1 meets: 21CFR177.1500 / CFR177.1395 testing follows regulations 21 CFR Parts 210, 211 and 820 Now I realize just because the material is approved doesn't mean it is approved after printed as it has to 'go through' the machine so that may require a COA. Of course any advice here is not taken as 'legal advice' just interested in what it takes to be able to properly produce surgical guides. From my understanding it is mostly a requirement of the client to get FDA approval, I would expect a surgical guide to be at least class 2 and likely class 3.
  2. I haven't worked with a tiff stack but I wonder where it gets the voxel size values from? I would check the tiff meta data and see what values are there. Guessing images are in DPI and fiji reads the values as mm... but then I would think the voxel size would be much smaller. I would expect the same result from ImageJ but worth a try too.
  3. So I have seen some questions here on embodi3D asking how to work with MRI data. I believe the main issue to be with attempting to segment the data using a threshold method. The democratiz3D feature of the website simplifies the segmentation process but as far as I can tell relies on thresholding which can work somewhat well for CT scans but for MRI is almost certain to fail. Using 3DSlicer I show the advantage of using a region growing method (FastGrowCut) vs threshold. The scan I am using is of a middle aged woman's foot available here The scan was optimized for segmenting bone and was performed on a 1.5T scanner. While a patient doesn't really have control of scan settings if you are a physician or researcher who does; picking the right settings is critical. Some of these different settings can be found on one of Dr. Mike's blog entries. For comparison purposes I first showed the kind of results achievable when segmenting an MRI using thresholds. With the goal of separating the bones out the result is obviously pretty worthless. To get the bones out of that resultant clump would take a ridiculous amount of effort in blender or similar software: If you read a previous blog entry of mine on using a region growing method I really don't like using thresholding for segmenting anatomy. So once again using a region growing method (FastGrowCut in this case) allows decent results even from an MRI scan. Now this was a relatively quick and rough segmentation of just the hindfoot but already it is much closer to having bones that could be printed. A further step of label map smoothing can further improve the rough results. The above shows just the calcaneous volume smoothed with its associated surface generated. Now I had done a more proper segmentation of this foot in the past where I spent more time to get the below result If the volume above is smoothed (in my case I used some of my matlab code) I can get the below result. Which looks much better. Segmenting a CT scan will still give better results for bone as the cortical bone doesn't show up well in MRI's (why the metatarsals and phalanges get a bit skinny), but CT scans are not always an option. So if you have been trying to segment an MRI scan and only get a messy clump I would encourage you to try a method a bit more modern than thresholding. However, keep in mind there are limits to what can be done with bad data. If the image is really noisy, has large voxels, or is optimized for the wrong type of anatomy there may be no way to get the results you want.
  4. Version 1.0.0

    Here is my right hand segmented and smoothed. All bones are included separately as well as combined together. The Radius, Ulna, and Soft Tissue have also been cut to make printing easier. The combined bones stl is with the arm bones cut. Segmentation of wrist bones wasn't ideal due to the somewhat low resolution of the scan... smoothing may be a bit excessive there to account for this. Refer to the shared scan volume to see the original data.


  5. Mikes Hand

    Version 1.0.0


    This is a subvolume from an abdomen CT scan from a 32 year old male. I happened to have my hand in the field of view (probably since I had just re-injured my shoulder from a skiing fall). Voxel Size: 0.835mm in plane 1.6mm out of plane


  6. Looks like good quality, is this with PVA and is the viewed side the top or support side? My experience with using PVA as a support is good but the interface is a bit rough. I know the UM3 uses a different PVA than I have used which may do a better job with the interface.
  7. It seems you're in luck I have a few scans from max inversion, internal rotation and plantar flexion to max eversion, external rotation and dorsiflexion... part of my masters thesis actually. They are MRI's so creating 3D models is not as easy as with CT scans. Visually the foot model you made looks good considering it came from 2D images. BTW the terms pronation and supination are better used for upper extremity than feet, the group I worked at which studies foot biomechanics doesn't use them as they are not well defined for lower extremities.
  8. Version 1.0.0


    MRI of a middle aged female held in maximum external rotation, eversion, and dorsiflexion. Not weight bearing other than necessary to hold foot in position. Relatively low quality scan: 1.5T MRI 0.7mm slice spacing 0.566 x 0.566 pixel spacing


  9. Version 1.0.0


    MRI of a middle aged female held in Neutral Orientation. Not weight bearing other than necessary to hold foot in position. Relatively high quality scan: 1.5T MRI 0.5mm slice spacing 0.566 x 0.566 pixel spacing


  10. Version 1.0.0


    MRI of a middle aged female held in maximum internal rotation, inversion, and plantar flexion. Not weight bearing other than necessary to hold foot in position. Relatively low quality scan: 1.5T MRI 0.7mm slice spacing 0.566 x 0.566 pixel spacing


  11. Well for my particular case its hard to say as I don't wear it 24/7. I swap between it and the cloth type. With tendonitis the printed brace is rigid and restrictive. Important for a broken bone but not so much for a soft tissue injury where it is important to have just limited mobility. I may tweak the design some more to give a bit more comfort and flexibility. Yes the early designs were far from usable/comfortable took some trial and error to get it right.
  12. While I haven't done this before from similar projects I can think of a fairly simple procedure: 1. Create 3D model of anatomy to do surgery on 2. Create cylinders to represent drill bits and place/orient them where you want 3. Create a block that will represent the jig and orient it so it overlaps the anatomy 4. Do boolean subtractions to remove the cylinders (create holes) and intersecting anatomy (create reference surface) Mike
  13. I would concur I mentioned thresholding for viewing data but that doesn't work well for MRI which does have a larger variety of 'styles' compared to CT. I would definitely start with orthogonal views but that may not be all that novel.
  14. 3D Printed Wrist Brace

    So I began to develop some pain in my right wrist which was later diagnosed as tendinitis. At the same time I had been looking at the CT scan of my abdomen and noticed they also captured my right hand as it was resting on my stomach during the scan (I had injured my right shoulder again). I recalled a concept project a while back I had seen: the CORTEX brace. It presented the idea of replacing the typical plaster cast with a 3D printed one which would prevent the issues of sweating and itchiness… as well as be much more stylish (though not allowing people to sign your cast). I had wanted to apply this to prosthesis sockets initially but never got past the idea stage. Looking around for how to create the ‘webbing’ style I found that meshmixer had the necessary capabilities. So I now had all the tools needed to make my own brace to partially immobilize my wrist. Once the surface model is created and loaded into meshmixer the first step is to cut off anatomy that you don't want in the model using 'plane cut'. Once the general shape of the brace is created the next step is to consider how the brace will be taken on and off. For my design I wanted to have one piece that is flexible enough to slide my wrist in. To create the 'slot' I found that I did a boolean in blender as meshmixer would crash when I tried to create the slot. With the brace model and slot in place the next step was to offset the surface since creating the voroni mesh would generate the tubes on both sides of the surface. This is done back in meshmixer and is fairly computationally intensive so partially reducing the mesh density first is a good idea. The next step is to further decimate the mesh to get the desired voroni mesh pattern. This takes a bit of playing around to get the desired style. Too dense and the resulting web structure will not have many openings which will be stronger but not as breathable. Too rough and the model may not conform to the surface well causing pressure points. The final step is to take the reduced mesh and web like structure using the 'make pattern' feature within meshmixer. There are various settings to be applied within this feature but setting 'Dual Edges' then adjusting the pipe size to double your offset will result in the inner edge of the webbing to just touch the skin of the initial model. Having never made a brace/cast before it took me a few iterations to get a design which I could easily don and doff (put on and take off). I also found that I could make a brace that held my wrist very rigidly but would be too restrictive. Also material selection became important. Initially I used ABS which is more flexible than PLA and I had it in a nice pink skin color. It turned out to be too rigid for the style I was designing. I found PETT (taulman t-glass) to work well as it had a lower modulus of elasticity meaning it was more flexible than ABS. After using the brace on and off for a few weeks I have found that it fits well and is surprisingly comfortable. I have taken a shower with it on as well as slept with it on. It doesn’t seem to smell as bad as the cheap and common cloth type braces. The main downsides have been taking it on and off is a bit challenging still and it is more restrictive of my motion as it behaves somewhere between a brace and a cast. There is definitely a great deal of potential for this type of cast though widespread adoption would require further technical development to simplify the process.
  15. At my rate for the 3D printing part it would cost under $100 and take less than a day to print (calculated around 13 hours).