About segmentation and three-dimensional reconstruction for CT

I have a question. CT images are scanned and photographed at a certain interval. For example, it is a plane scan at an interval of 1mm. When we segment, we can only segment the target area of the scanning surface. For the images with a vertical interval of 1mm that are not scanned, what is the basis for interpolation and filling?

I’m not exactly sure what you are asking. Could you add a drawing to make things more clear? Mark the “target area of the scanning surface”, and the “interpolation and filling” you are interested in. Thank you!