[Importance of computed tomography in irradiation planning for the thoracic region (author's transl)]

The target volumes, anatomical distances and isodose curves in 62 patients undergoing irradiation of the thoracic region have been defined and compared for treatment planning, using an idealized transversal body section on the one hand, and computed tomograms on the other hand. 74% revealed nonconformance of the target volumes, and correction on the radiation field was therefore necessary in 62%, according to the CT-findings. Computed tomograms are superior to conventional treatment planning because they present individual body sections. Thus, deviations of the peak doses amounted to more than 10%: in the region of the mediastinum 7%, in the region of th lungs 29%, and in the region of the spinal cord 13% of the cases.