SU‐E‐T‐628: Dosimetric Evaluation of Proton Arc Therapy for Brain Stereotactic Radiotherapy

Purpose: The aim of this study is to evaluate the dosimetric comparison of proton arc therapy based on dose‐volume histograms (DVH) analysis obtained by brainstereotactic radiotherapy plans. Methods: Treatment plans using dynamic conformal arc therapy and proton arc therapy were generated for 10 patients with brain metastases. Single‐dose radiosurgery(SRS) and fractionated stereotactic radiotherapy (FSRT) were used. The mean doses were 13.5 Gy for the SRS group and 36 Gy in 6 fractions for the FSRT group. The delivered prescription doses to 100% isodose line were chosen on the basis of tumor size and location. The normal tissue complication probability (NTCP) and equivalent uniform dose (EUD) were investigated for each treatment plans. Results: The normal braindose at V5 and V10 was significantly decreased using proton arc therapy compare to dynamic conformal arc therapy. The radiobiological parameters of NTCP and EUD showed a complete tumorcontrol limiting the organs at risk damage. Proton arc therapy shows good target coverage compare to dynamic conformal arc therapy. Conclusions: In this study, we present that proton arc therapy was superior to dynamic conformal arc therapy in stereotactic radiotherapy. The low doseradiotherapy could be the best way for young children.