RTHP-16. RADIATION INDUCED SIGNAL CHANGES ON MAGNETIC RESONANCE IMAGING IN ADULT PATIENTS WITH BRAIN TUMORS TREATED WITH PENCIL BEAM SCANNING PROTON THERAPY

摘要

OBJECTIVES: We report radiation induced signal changes (RIC) on MRI in adult patients with brain tumors treated with pencil beam scanning proton therapy (PBS-PRT).METHODSAll patients > 18 years receiving standard fractionation RT (4554 GyE) for a primary brain tumor with > 6 month follow-up were included. Post-RT MRIs were compared to the pre-RT scans. RIC was defined as new contrast enhancement (CET1W) and/or T2-FLAIR (T2W) changes MRI outside the GTV (CTCAE v4.0 grading was used). Monte Carlo, RBE (relative biologic effectiveness), and LET plan evaluation pre-RT were performed. Tumor, clinical and treatment factors were analyzed.