[Contribution of CT and MRI to radiation therapy]

The contribution of CT to radiation therapy has been enormous. The most basic contribution has been that CT has made almost all malignant tumors visible, which has improved radiation therapy not only in the planning phase but also in the effect-estimating phase. As some examples, CT has improved the effects of radiation therapy for cancer of the maxillary sinus and of the uterine cervix, and the results from our department have already been published. The contribution of MRI to radiation therapy should be very great in future wherever MRI diagnostics are established. Even now, however, its ability to visualize cross-sectional anatomy in any area is an aid to radiation therapy both in planning and in estimating the degree of effect.