Volume calculations are inconsistent on Bone CTs

I am using slicer to separate cortical and trabecular bone in CT scans from morphosource. I use the threshold effect to first identify the cortical bone then use the wrap solidify tool to creat a segment with all bone volume. Then I go to quantification → segment statistics to obtain the volumes in mm^3.

However, on some bone scans the total volume comes out at 5700 mm^3 and then another scan of a bone the same length will give a volume of only 1800.

Any ideas of what I am doing wrong? The segments are cleaned up to ensure no background measurement. The ratio between the two is always roughly correct so i do nbot think it is a measurement error but rather a scaling one.

Thanks in advance!

Is this the same species?

Make sure you import the data with the correct scale.