About CT slices

I have a question, that is, medical CT images are slice images, and the shooting interval is uncertain. How does slicer software fit these slice images into three-dimensional models, and there will be an interval between slices

The distance between slices is usually a DICOM parameter so should be there

Yes, I know that the distance between slices is a parameter, which is saved in the NII file. However, this is only the shooting interval of labeled slices. However, there is no image capture data for the distance between intervals. How do we show the images at this interval