We introduce a novel approach to specify and edit volumes of interest (VOI for short)
interactively. Enhancing the capabilities of standard systems we provide tools to edit the VOI
by defining a not necessarily convex polyhedral bounding object. We suggest to use low-
level editing interactions for moving, inserting and deleting vertices, edges and faces of the
polyhedron. The low-level operations can be used as building blocks for more complex
higher order operations fitting the application demands. Flexible initialization allows the user …