MLC tracking for lung SABR is feasible, efficient and delivers high-precision target dose and lower normal tissue dose

Background and purposeThe purpose of this work is to present the clinical experience from first-in-human trial real-time tumor targeting via MLC tracking for stereotactic ablative body radiotherapy (SABR) lung lesions.Methods materialsSeventeen patients with stage 1 non-small cell cancer (NSCLC) or metastases were included in a study electromagnetic transponder–guided SABR (NCT02514512). Patients had transponders inserted near tumor. An plan was generated planning target volume (PTV) expanded 5 mm end-exhale gross (GTV). A clinically approved comparator PTV 4DCT-derived internal (ITV). Treatment delivered using standard linear accelerator continuously adapt based on transponder motion. Treated volumes reconstructed dose compared between ITV-based treatment.ResultsAll seventeen successfully treated (70 successful fractions). treatment delivery time averaged 8 minutes. The start CBCT end 22 16/17 smaller than (range ?1.6% 44% reduction, ?0.6 18 cc). Reductions mean (27 cGy) V20Gy (50 cc) statistically significant (p < 0.02). Reconstruction doses confirmed improvement GTV D98% 0.05) planned plans.ConclusionThe first treatments have been performed patients. feasible, efficient delivers high-precision lower normal tissue dose.