CT-based simulation with laser patient marking.

A CT-based simulator has been assembled based on a commercial CT scanner, virtual simulation software developed at the University of North Carolina and a laser drawing device to transfer the radiation portals from the virtual simulator to the patient. The simulation process can be completed in approximately 1 h; under most cases, the treatment portals can be designed and the patient marked in one session. The device has an inherent accuracy of +/- 1 mm. The portal projection accuracy in clinical cases is observed to be better than 2 mm.