RADT-06. SPARING OF MOTOR STRUCTURES IN ADJUVANT RADIATION THERAPY AFTER RESECTION OF BRAIN METASTASES: APPLICATION OF NTMS-DERIVED DTI-BASED MOTOR FIBER TRACKING IN ADJUVANT STEREOTACTIC RT TREATMENT PLANNING

Abstract BACKGROUND Resection of brain metastases (BM) close to the motor cortex and corticospinal tract (CST) bears a significant risk for treatment-related morbidity. Navigated transcranial mapping (nTMS) combined with diffusion-tensor-imaging (DTI) based fiber tracking (DTI-FTTMS) is valuable tool guide neurosurgeon along CST preserve function. This study aims proof practicability DTI-FTTMS in local adjuvant stereotactic RT planning management BM. Method: Pre-surgical generated DTI-FTTMS-based reconstructions 24 patients 25 resected BM were incorporated into system elastic fused imaging. The was delineated as volume (PRV-FTTMS). Fractionated intensity-modulated (IMRT) plans (7 x 5 Gy) retrospectively calculated then optimized PRV-FTTMS. Areas covered by target (PTV) not spared (overlap). RESULTS In regular mean dose (Dmean) complete PRV-FTTMS 5.4 ± 2.5 Gy. Regarding portions within 8.75 Gy (25% prescription dose) isodose level Dmean 18.2 4.3 after plan optimization 13.1 3.8Gy (-28.0%, p < 0.001). Within 17.5 (50%) line reduced 31.7% from 24.3 3 16.6 4.8 (p< There no decline effective treatment dose, PTV 36.9 0.7 vs. 37.7 1.4Gy (p=0.013) adaption. coverage (V35Gy(%)*100) did change optimization: 0.99 (p=0.43). Dose constraints organs at all met both plans. CONCLUSION tracts could be implemented cavities resection A reduction structures critical levels seems possible without reducing dose. However, functional benefit needs investigated prospectively clinical trials.