yes the voxel size is 1x1x1mm, thanks a lot.
Just curious, if the voxel size is other, such as 0.5mm x 0.5mm x 0.5 mm, then the first output would be still the voxels, but the second should be volume = voxels x voxel_size(0.5x0.5x0.5), is this correct? many thanks