in the treatment of a tumor with radiation therapy is enhanced by a weak magnetic field , 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 is continued after exposure to a free radical - creating therapy is ceased or diminished , thereby increasing the lifetimes of free radicals which have already been created . in another preferred embodiment a magnetic field 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 is also disclosed .