Three-dimensional radiation treatment planning: Principles and practice

The clinical outcome in radiooncological treatment of malignant tumors such as glioblastomas and non-small-cell lung cancer is disappointing. In order to obtain a better local tumor control and survival rates, dose escalation seems to be an appropriate way. Especially in those anatomical sites where radiosensitive tissues surround the tumor a further increase of the total radiation dose with conventional radiotherapy is critical. In numerous stud ies 3-D treatment planning and its clinical realization as conformal radiot herapy demonstrated an improvement in dose distribution for the target volu me as well as the surrounding radiosensitive tissues compared with 2-D conv entional treatment planning. The high-dose region was very well conformed t o the tumor. Outside the tumor the radiation dose decreased steeply. For pr ostate cancer it has been shown that an increase of the total dose is toler able. The number of normal tissue complications remained low. We expect tha t 3-D treatment planning and conformal radiotherapy may substantially impro ve the therapeutic ratio. There is no doubt that oncology in general, and e specially radiooncology, may profit from this new technology in the near fu ture. Continued clinical research, however, is necessary to take full advan tage of this promising method.