Skull stripping usually refers to removing everything outside the brain in MRI images. Probably itk-skullstripping performs this operation. In CT images the problem is completely different, much easier, as the skull can be segmented by simple global thresholding.
You can find a fully automatic method (you need to run automatic steps, which can be easilty automated) for 3D. The problem is harder to implement in 2D and CT image acquisitions are very rarely limited to a single slice, but if needed then you could develop a similar method (segment the skull, close the gaps, and extract the largest cavity).