Single-session lung radiosurgery using robotic image-guided real-time respiratory tumor tracking.

Abstract

Objective: To describe the clinical feasibility for single session lung radiosurgery using a real-time robotic system with respiratory tracking. Methods: We treated 62 patients with 75 lung tumors with robotic radiosurgery (CyberKnife®, Accuray). Twenty-two patients had primary tumors and 40 had metastatic tumors. Forty-two patients underwent computed tomography-guided percutaneous placement of one fiducial directly into the tumor. Ten patients were treated using spinal tracking, and in another ten patients fiducial free lung tumor tracking (Xsight lung, Accuray Inc.) was performed. All patients were treated with single session radiosurgery to a dose of 22 - 24 Gy. The median tumor volume was 15 cc (1.5 – 64 cc). The last 23 patients were planned with a new Monte Carlo treatment planning algorithm. Follow-up CT scanning was performed every two months. Results: All patients could be treated with the automated robotic technique. The 6-, 12-, 24 actuarial local tumor control rate was 98%, 88% and 88%, respectively. The median follow up time was 10 months (range: 0.4 – 30 months). Six patients (10%) required a chest tube insertion after fiducial implantation because of pneumothorax. Four patients experienced nausea after treatment. No other short-term adverse reactions were found. Fifteen patients showed Grade 1 and one patient Grade 2 signs of pneumonitis. No Grade 3 or grade 4 toxicity was detected. Conclusions: Single-session radiosurgery for lung tumor tracking using the described technology is a stable, safe, and feasible concept for respiratory tracking of tumors during robotic lung radiosurgery in selected patients. The single fraction approach is convenient for the patient and does not interfere with concomitant systemic treatments. Longer follow-up is needed for definitive clinical results.