In the treatment of a tumor (126) with radiation therapy (122) is enhanced by a weak magnetic field (130), the field strength time sequence of exposure and shape and contour of the magnetic field are varied to achieve desired results. In one separate aspect, exposure to a magnetic field (130) is continued after exposure to a free radical-creating therapy is ceased or diminished, thereby increasing the lifetimes of free radicals that have already been created. In another preferred embodiment a magnetic field (13) is strategically placed to avoid extending the lives of free radicals in tissue through which a free radical-creating beam must pass, to reach a tumor. This application discloses quantitative parameters for field strength and exposure time to create concentrations and reactivity of free radicals, including long-lived free radicals and discloses the use of shaped, contoured, and designed electromagnetic fields. A treatment planning station (200) is also disclosed.