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Dr. Mike

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Everything posted by Dr. Mike

  1. Wow. Great tip. I'm definitely going to try it. Thanks!
  2. Here is an article on the benefits of using 3D printed temporal bones for surgical training https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6703115/
  3. This is outstanding. Thank you very much for sharing. Dr. Mike
  4. I agree. Even with polyjet, there is the issue of wall thickness. The leaflets are very thin and thus hard to print with any printing technology. With great difficulty I designed an 3D printed a customized sheep heart for flow testing of TAVR devices using elastic material.
  5. valchanov, is shrinking a factor with STL prints or just with FDM prints?
  6. Valchanov, I downloaded the file and took a look. I see right ventricular hypertrophy, a large VSD, pulmonary valve atresia/stenosis and an overriding aorta that is also on the right side. I think this is Tetrology of Fallot. It is a cool scan! Dr. Mike
  7. Is it a thin slice series? 791 seems very large, even for thin slices.
  8. Increase the threshold level. It looks like you are getting soft tissue included with your conversion. Make the threshold 300 or so and it should eliminate a lot of the soft tissue.
  9. Interesting. Can you give some examples of your work?
  10. I've found that printing anatomic parts with a single extruder is difficult, primarily due to limitations on supports with complex, organic geometries. Dual extruder with soluble interfaces is what I use if FDM is required. Stereolithography is also an option although it is messier and arguably requires more postprocessing. Anyone have success with a regular single extruder (excluding specialized setups like MMU)? Mike
    We printed this canine pelvis and lower extremities model with patellar subluxation for a customer in detailed white resin. The model came out great!
    We printed this model for a customer in white PLA. The print took quite a long time, but came out great!
  11. I think this is the biggest thoracic aneurysm I have ever seen. I am glad the patient survived!
  12. Valchanov, as always terrific post. Thanks for sharing!
  13. There shouldn't be. Just know that the unit of measurement is in millimeters. If you import the STL file into printer software and specify that the unit of measurement is cm, inches, or feet, your model will be HUGE. Hope this helps. Mike
  14. Flaviu, Can you go into more detail with your Palette 2 experience? The concept looked great in theory when it came out, but at the time I heard it was still problematic. Are you finding success now?
  15. If you are only interested in bone, the lower dose is probably fine. Make sure you get sequences with soft tissue reconstruction algorithm in addition to the standard bone algorithm. Edge enhancement with the bone algorithm causes speckling, which can make bone segmentation more difficult. See my blog article on selecting a good scan for 3D printing below for details. Look at the section on reconstruction kernel.
  16. A member recently messaged me a comment. I am posting the response here to help the general community: "Regarding democratiz3D, I like that it's simple to use. Being able to convert to even higher resolution STL files for free would be nice." My response: Do you know about our Ultra quality settings? If you set democratiz3D to use ultra quality, you will get an output STL with about 3 million polygons. That is super high resolution. Files of that resolution are difficult to even open on regular PCs because of the extreme detail. Ultra quality STLs take about an hour of server time to generate, and thus we cannot give them away for free. They are available with Premium subscriptions. However, you can still get them for free with our Pay or Share program. If you agree to share your STL with the community, we will pick up the tab for the conversion. It is free for you as our gift because you gave something to the community. Hope this helps! Dr. Mike
  17. Your guess is right. We can't associate shared files with photos of a person due to the need to maintain privacy. Good luck with your project and be sure to post the results here. I am sure the community will be interested in your work. Dr. Mike
  18. A member recently asked the following question: "Is there a skull that would work for someone who is interested in facial reconstruction sculpting or forensic sculpting? I searched some of the skulls but found most seem to have hollow spaces. " We have a variety of skulls available for download and 3D print -- several hundred at least. I am sure you can find something representative of what you need. I am not sure what you mean by "hollow spaces." A normal skull has many hollow spaces, including the paranasal sinuses, mastoid air cells, and of course the intracranial portion where the brain sits. Are you seeking something different? Dr. Mike
  19. A user asked us the following: "Is it possible to get kidneys and near by attached vascular and possible tumors cut out of a CT scan? " The answer is yes. This will probably require lots of time manually segmenting the various structures, but it is possible. It is easiest of the CT scan is with IV contrast and in thin slices. Attached is a picture of a custom print job we did for a medical device company. If you need a custom print print please contact us. If you want to learn more about custom models for medical device testing or other purposes, you can find more info here.
  20. A member asked us the following question: "I uploaded a NRRD file and was hoping to be able to download it as an STL - any advice?" You can use our democratiz3D service to automatically convert an NRRD into a 3D printable bone STL model. You can find more about democratiz3D here. There are many tutorials available here. Hope this helps.
  21. You are diving into the deep topic of medical imaging scans for 3D printing. I wrote a blog article on how to get the most out of your scan here. Take a look as it is very helpful. 3mm is not bad for a CT scan for 3D printing. In order to understand why the radiology department created 3 mm slices, you need to understand how CT scans work. Modern CT scanners do not acquire data in slices. Rather, the acquisition is helical. The patient moves in the scanner on the Z axis at a fixed speed, while the x-ray tube spins around that axis during acquisition. As a result, relative to the body, the x-ray tube moves around like a helix, i.e. corkscrew. The raw data from this acquisition is stored in memory in the CT scanner. It is then reconstructed into flat slices that can be of any thickness anywhere from 0.5 mm to 5 mm. Thinner slices are not always better however. There is a fixed number of x-ray photons that were acquired during the scan. When the slices are created after the fact, the data that those photons created is spread among the slices. If you have a lot of very thin slices then there are few photons per slice. Just like with a handheld camera when you shoot in low light, having a low number of photons results in a grainy image. The exact same things happen with a CT scanner. Thin slices tend to be very grainy and it can be difficult to detect abnormalities when the image quality is poor. Thicker slices on the other hand are fewer in number and have more photons per slice and thus are less grainy. Think of a nice photograph from a handheld camera on a bright sunny day. There are so many photons to make the image, the image is crystal clear. Thicker slices, while giving a higher quality image, are also thicker, and very small structures are harder to see. Therefore, if you had a CT scan and reconstructed 0.5 mm slices, those images would be much grainier and of lower quality than if you had reconstructed with 5 mm slices. When the scan is being taken the radiologist determines what slice thickness is the best for diagnosing the problem at hand. If you're getting a CT scan of the abdomen for appendicitis, you will get 5 mm slices. If you have a problem with your middle tier and are getting a CT scan of the mastoid, you'll probably get 0.5 mm slices. It should be noted that the raw data from the scan acquisition takes up a lot of memory. While the reconstructed slices are saved in the hospitals radiology system, the raw data from the scan is stored on the physical scanner itself. Typically after a few days that data is purged to make room for new scan data. So, after a few days it is not possible to generate any new slices from the scan, as the raw data has been purged. My guess is that 3 mm slices is as good as you are ever going to be able to get from your scan. To reduce the stairstep artifact, run a smoothing algorithm on your model. This should reduce that appearance. I hope this helps Dr. Mike
  22. 1) Nothing in this forum should be considered medical advice. 2) The scan shows some extent of pectus excavatum. Heart is a bit displaced as a result. 3) Evaluation of the heart itself is poor because the scan was not protocoled to examine the heart (i.e. no ECG gating). My guess is they were looking for PE, and there is no obvious one. Good luck
  23. If you increase the threshold value (150->250 Hounsfield units), that will tend to include less bone in the model. If decrease it, more bone will be included. Just want to check -- are you starting with a CT or an MRI. CTs work better. Hope this helps. Dr. Mike
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