Electromagnetic-Guided MLC Tracking Radiation Therapy for Prostate Cancer Patients: Prospective Clinical Trial Results

Purpose To report on the primary and secondary outcomes of a prospective clinical trial of electromagnetic-guided multileaf collimator (MLC) tracking radiation therapy for prostate cancer. Methods and Materials Twenty-eight men with prostate cancer were treated with electromagnetic-guided MLC tracking with volumetric modulated arc therapy. A total of 858 fractions were delivered, with the dose per fraction ranging from 2 to 13.75 Gy. The primary outcome was feasibility, with success determined if >95% of fractions were successfully delivered. The secondary outcomes were ( 1 ) the improvement in beam-target geometric alignment, ( 2 ) the improvement in dosimetric coverage of the prostate and avoidance of critical structures, and ( 3 ) no acute grade ≥3 genitourinary or gastrointestinal toxicity. Results All 858 planned fractions were successfully delivered with MLC tracking, demonstrating the primary outcome of feasibility ( P Conclusions Electromagnetic-guided MLC tracking radiation therapy for prostate cancer is feasible. The patients received improved geometric targeting and delivered dose distributions that were closer to those planned than they would have received without electromagnetic-guided MLC tracking. No significant acute toxicity was observed.