Blender for virtual surgery planning I'm trying to see if I can use Blender for virtual surgery planning.
I have an STL model of the patient's skull. I would like to cut out pieces of the skull and manipulate them. Here's an example of the cuts I would like to make 

What would be the easiest way to achieve this?

It seems to me that the easiest way would be if I could just draw the cut lines on the model. I think it would be enough if I could split just the outer surface with a curve.

So far I have tried using boolean operations to make the cuts. I can snap the vertices to the surface and then create a solid which I can use for the boolean operations. I'm just wondering if there's a more elegant solution to this problem.
Thank you for the advice!

I used the grease pencil to mark the cut lines and booleans to split the skull into pieces.
At first I drew the outline of the cuts on the skull, then decimated the mesh so I could edit the boolean meshes in real time. It worked quite well. It would be really nice if I could just draw the cut lines on the model.
Here is the end result-->