Hello
I have a problem with loaded ct scans. In te red window ct scany are properly visible but in green an yellow view ct scan are stretched or narrowed. I send screen with my problem.
Best,
Pawel
Please post what kind of files these are and how you loaded them (e.g. dicom, tiff, etc).
This Ct scans are tiff and I loaded them as tiff.
That explains a lot. Tiff files don’t track the spacing so you need to add it manually. In the Volumes → Volume Information you can add the spacing manually for the pixel and slice spacing. Or you may find SlicerMorph’s ImageStacks module useful.
Thank you:) I have different ct scans for several skulls and only one ct scan loaded good although these ct scan also are Tiff files.
I add the spacing manually and I think that is all good. Do I have to add in the Image spacing same value (e.g 30 mm) to all ct scan in windows (red , yellow and green) have this same proportion?
Best,
You have to check that with whoever provided you with the dataset. Often microCT scans are isotropic (same spacing along all axes), but not guaranteed to be that way.
Also spacing units are mm. I don’t think you have 30mm spacing in your scan. 30 micrometers perhaps? (=0.030mm). Again check this with whoever gave you the data.
Thank you for your help.
Do I understand correctly that the introduced good values in the Image spacing will cause that measurements made on ct scans will be correct? For example, I know that the skull is 40 mm lenght.
Correct data in the Image spacing will cause that measurements made on ct scans skull is also 40 mm length.
Yes, if the spacing is correct the measurements should be correct. But using a format such as tiff where you need to enter values manually there’s always room for human error. Better would be to work on the acquisition process to use a format where the spacing is automatically encoded (perhaps dicom) and do some test runs with calibration phantoms to be sure it’s working as expected.