Experimental application of virtual (artificial) reality computer systems in using diagnostic images in the planning of radiotherapy regimes. Here, a scientist at the University of North Carolina is using a headset to view a virtual (computer-generated) 3-D images of the lungs (red) revealing two groups of parallel radiotherapy beams converging on the tumour (yellow) located in the upper lobe of the lung at left. In this type of radiotherapy, several beams are directed at the tumour in sequence from several points around the body. The treatment regime might be accurately planned using the virtual patient prior to treatment in earnest.