Stereotactic interstitial radiosurgery with a miniature X-ray device in the minimally invasive treatment of selected tumors in the thalamus and the basal Ganglia.

The aim of this study was to evaluate the role of interstitial radiosurgery (IR) using the photon radiosurgery system (PRS) in the treatment of selected tumors within the thalamus and the basal ganglia. The PRS is a miniature X-ray generator that was developed for interstitial irradiation. This series included 14 patients (5 with glioblastomas, 4 with low-grade astrocytomas and 5 with metastases) harboring spheroidal lesions with dimensions ranging from 13 to 42 mm (mean 30 mm). After stereotactic biopsy, a radiation dose ranging from 6 to 15.4 Gy (mean 11.3 Gy) was delivered at the target volume margins. Follow-up varied from 3 to 26 months (mean 10.2 months). In the group of glioblastomas, 3 patients died (3-12 months after the procedure) because of tumor progression, while the remaining had tumor control. Two patients with metastases died from systemic disease (4-9 months after the treatment), and 3 were alive and well at the end of the study. Local control was achieved in all metastases. Patients with low-grade astrocytomas were well and imaging studies showed tumor control PRS IR is a minimally invasive procedure for the treatment of selected glial or secondary brain tumors. Compared to conventional radiosurgery (brachytherapy and external radiosurgery), PRS IR presents dose delivery characteristics useful for the treatment of tumors in the thalamus and basal ganglia, without inconveniences such as handling radioisotopes, the need of expensive facilities and radiation protection measures. Although the clinical value needs further investigations, PRS IR seems to be effective in metastases while it provides less benefit in malignant gliomas. PRS IR could have a major role in the treatment of low-grade astrocytomas.