A dosimetrie method for implanting solid radioactive material in continous and parallel lines (needles or wire) is described. An axial tomogram through the center of the area to be irradiated, and perpendicular to the needles or wires, provides an accurate representation of their distribution. The dose delivered to various points of the tomographie layer can be calculated from standard isodose curves. The method has been used in cases of carcinoma of the oropharynx, it is accurate and time-saving and may be applied to other sites.