Once a VOI has been defined, several tools are available for its modification. The tools operate on the different definition levels:
•Operations on the entire VOI level like scaling change all contours in all slices at once.
•Operations on the ROI level change all contours in one slice at once.
•Operations on the contour level only change the selected contour in the current slice.
For each of the levels there is a toolbar illustrated below. Note that the ROI and CTR toolbars need to be toggled as they share the same location. To switch them please activate the indicated button at the top.
Contour VOIs are formed from a stack of planar ROIs, which themselves consist of a set of contours per slice. On each of these three levels a set of similar operations are supported via the toolbar:
•Scaling: The shape can be adjusted by dragging the edges of the object bounding box.
•Clearing: The contents of the object is cleared, but the object continues to exist and can be used again for a new definition.
•Copy/Paste: An object can be copied to the clipboard, and then pasted into an empty object on the same hierarchy level.
•Mirroring: An object can be mirrored with respect to the central axes of the image volume.
•Propagation: The aim of propagating an object is to easily get a copy of an existing object in a neighboring slice or frame. Propagation can work in both directions.