DORADOselect 4 is based on patented technology (EP 0687443, US5657386) and allows isocenter marking without table movement as well as MLC field marking. DORADOselect 4 uses 5 moving lasers: 2 laser for the lateral lines at the sides, 2 lasers forming the transversal line and one laser for the sagittal line in the ceiling system. The rails at the sides may be mounted on the wall or put up as a post.