A method for planning treatment of intraoperative radiotherapy

Intraoperative ultrasonography (IOUS) is useful in planning treatment by intraoperative radiotherapy (IORT), since it clearly visualizes the contour of the tumor or the target volume. The depth of the tumor or the target volume can be measured by IOUS; therefore the optimum energy of the electron beam which contains them in 90% of the maximum dose of the isodose curve can be selected. The dose of radiation to the adjacent structures should be kept to a minimum. By the use of a treatment planning unit (Theraplan), the contours of the organ on the ultrasonography could be traced with a light pen, and the isodose curve of several electron energies could be demonstrated on the input image. Since this procedure required only a few minutes, the real time treatment by IORT could be planned. (author)