Wrong size on the 3D modell

Hi,

I have a CT on a dog that I doing a 3D modell from:
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And this is the result

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But the Word from the veterinary experts in that this wrong, the femur bone should be bigger. So the dimensions on the bone is not correct. We print this modell out and it does not look like reality, it needs to be perfect. Can it have with the position the dog have when the CT is taken? or can we trust the program to 100%?

Thanks in advice!
/Carolina

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Dear Caroline,

the size and proportion of the femur looks normal to me as a person who assembled over 200 pieces of dog skeletons. Some dogs (especialy mongrel dogs) can have interesting sizes according their bones.
Of course it is only my suggestion, not a software specific answer:)

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Slicer reconstructs models from volumes very robustly and accurately. DICOM image import is the only part of the workflow that might go wrong in case the scanner saves images that are not fully compliant to the DICOM standard.

  • What CT scanner brand/model do you use?
  • What image resolution and slice spacing was set in the scanner?
  • What image spacing values do you see in Volumes module / Volume Information / Image Spacing?
  • Did you use DICOM module to load the image? Did you get any warning when you loaded the image?
  • What Slicer version did you use?
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Thanks for your answer, I do this for a costumer and only geat the CT link by email. But I can check this up, but not any no warning when I load the image. yes I use the DICOM module to load the image.
Slicer 4.9.0.
Image spacing:
image

Thanks! //Carolina

You can find CT scanner manufacturer/model in DICOM fields: in DICOM module, select your image series and click Metadata button (look for Manufacturer and ManufacturerModelName fields). It is important to know this because clinical scanners implement DICOM standard correctly, but many microCTs, industrial, or pre-clinical devices have faulty implementation.

Please use at least Slicer-4.10.0.

2 Likes

Hi Ors Petnehazy!

Thanks for your answer!
Your comment meaning a lot! That is my opinion to, I have not seen this dog but on the CT it looks just like a typ of mongrel dog.

I will have a discussion with the veterinarian agen. It’s hard at first to get them to trust in the 3D-printing technology.

Thanks again! //Carolina

When you are developing a new workflow, with new devices, data formats, processing steps, etc. it is always advisable to use test data sets for that ground truth is available. For your case, you could start with scanning a rigid object, such as a bone phantom (or just any object that you can measure and compare to the final 3D-printed object).

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Hi Andras,

Thanks for your valuable information. This was a philips brillinace 16, how do I now If this CT have a fault in the implemantation? Or which CT-Scans how has that problem?

Thanks! Amazing, I will Think about that!

Philips Brilliance 16 is a widely used clinical scanner. Such systems export DICOM images correctly.

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Dear Carolina,

Sometimes we have struggles with our models as well, especially with this:)kutyacsont_es_%C3%A9rhal%C3%B3zat_02

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I would take a guess and say that your dicom z spacing is incorrect giving you a very elongated view of the hindlimb. I second @lassoan suggestion validating your input pipeline.

@Carolina3D you could also upload the data set to dropbox/onedrive and post the link so that we can check if there is anything suspicious there.

If that’s not possible then send us slice position/orientation data as described here: Problem with sagittal and coronal view from CCTA DICOM files

Is the data set consists of hundreds of files or just a couple of files?

Amazing job, impressing!

The link google drive:

The data set consists in 100 of files.

Thanks for your time and Amazing help!

Thank you for sending the slice positions. It shows that slice spacing is indeed 1.0mm, which is correct. Number of images is 359, which is also correct. So, it seems that the geometry should be good.

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Thanks for your expertise!