During the research and clinical studies, we have worked hard on how to explain something difficult in an intiuitive and instructive ways. Many things has been tried and we have come up with a special voxel based "Green Lighting" system.
This tutorial system guides the user through a series of steps in different surgical procedures. This is done by presenting the next layer that needs to be drilled away as colored green. Now the user just need to remove this bone and when done take in the next step. In the background the system monitors the amount removed inside and outside the reference volume.