Image-guided therapy planning for interventional stereotactic therapy of brain tumors

A treatment planning system for stereotactical neurosurgery has been developed. A modular system has been designed which is readily extendable. Different modalities of tomography (CT, MRI) can be correlated and presented simultaneously in transverse, frontal and sagittal reconstructions. The volumes of interest are segmented with respect to the different modalities, and the positions of the catheters are defined. The calculation of dose must be adapted to the physical requirements of the therapy and is designed as an independent process. The calculated data are shown in various presentations. The treatment planning system is applied to intratumoral chemotherapy. The drug is encapsulated in small carriers for prolonged release and injected via catheters directly 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 distribution it is necessary to use a great number of catheters due to the limited diffusion of drug, which is not practical in neurosurgery. Therefore this therapy concept is useful for small volumes only. Interstitial hyperthermia and brachytherapy, in contrast to intratumoral chemotherapy, show successful clinical results.