Fig. 1.

Impact of 3D conformal radiotherapy (RCT) versus ‘older’ techniques on normal tissue radiation dose. In patients with 3 target volumes (e.g. 3 metastatic lesions), the gross tumor volume lies in the range of 100–150 cm³. If simple treatment techniques are used (e.g. anterior-posterior opposing portals), a large amount of normal tissue receives the target dose. If conformal treatment techniques are used, the volume of irradiated normal tissue, and hence the risk of acute (and late) side effects, can be dramatically decreased.