IMAGE-GUIDED TREATMENT PLANNING FOR INTER VENTIONAL STEREOTAXIC THERAPY OF BRAIN-TUMORS

A treatment planning system for stereotactical neurosurgery has been d eveloped. A modular system has been designed which is readily extendab le. Different modalities of tomography (CT, MRI) can be correlated and presented simultaneously in transverse, frontal and sagittal reconstr uctions. The volumes of interest are segmented with respect to the dif ferent modalities, and the positions of the catheters are defined. The calculation of dose must be adapted to the physical requirements of t he therapy and is designed as an independent process. The calculated d ata are shown in various presentations. The treatment planning system is applied to intratumoral chemotherapy. The drug is encapsulated in s mall carriers for prolonged release and injected via catheters directl y into the tumor interstitium, bypassing the blood-brain barrier. The dose is calculated using the time-dependent, three-dimensional finite elements method. To achieve homogeneous temporal and spatial drug dist ribution it is necessary to use a great number of catheters due to the limited diffusion of drug, which is not practical in neurosurgery. Th erefore this therapy concept is useful for small volumes only. Interst itial hyperthermia and brachytherapy, in contrast to intratumoral chem otherapy, show successful clinical results.