Voxeltool Voxtool Voxtool from General Electric.
Segmentation is done through lower and higher HU-thresholds.
Intersection, union, difference and delta-functions between manipulated models. I've crashed it only a few times. Restarting the program or rebooting clears occasional memory-problems. In the current version area-measurements require at least two contiguos slices which is also annoying. If the 3D-model has to use more than 60 512x512 image's space as virtual memory the program is too slow to use interactively.