Color isodose curve plotter applied to beam focus radiography.

An apparatus was constructed to facilitate superimposition of the beam focus radiogram upon the axial transverse tomogram, in order to guide subsequent radia tion therapy more accurately. The apparatus automatically draws six isodose curves in three colors, by plotting the relative doses of the beam focus radiogram. In addition, the isodose chart was made at the same magnification as that of the axial transverse tomogram. A satisfactory and reliable technique was achieved. The accuracy and the reproducibility of the apparatus was good. Clinical applica tion of this method to a case of hypophyseal tumor is described.