Technical Description, Phantom Accuracy, and Clinical Feasibility for Single-Session Lung Radiosurgery Using Robotic Image-Guided Real-time Respiratory Tumor Tracking

Abstract

To describe the technological background, the accuracy, and clinical feasibility for single session lung radiosurgery using a real-time robotic system with respiratory tracking. The latest version of image-guided real-time respiratory tracking software (Synchrony®, Accuray Incorporated, Sunnyvale, CA) was applied and is described. Accuracy measurements were performed using a newly designed moving phantom model. We treated 15 patients with 19 lung tumors with robotic radiosurgery (CyberKnife®, Accuray) using the same treatment parameters for all patients. Ten patients had primary tumors and five had metastatic tumors.All patients underwent computed tomography-guided percutaneous placement of one fiducial directly into the tumor, and were all treated with single session radiosurgery to a dose of 24 Gy. Follow up CT scanning was performed every two months.All patients could be treated with the automated robotic technique. The respiratory tracking error was less than 1 mm and the overall shape of the dose profile was not affected by target motion and/or phase shift between fiducial and optical marker motion. Two patients required a chest tube insertion after fiducial implantation because of pneumothorax. One patient experienced nausea after treatment. No other short-term adverse reactions were found. One patient showed imaging signs of pneumonitis without a clinical correlation.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. Longer follow-up is needed for definitive clinical results.

The CyberKnife radiosurgery system for lung cancer

“…However, in a later publication, they reported a pneumothorax rate of 16% after the placement of 72 fiducials in 25 patients [26]. Muacevic et al reported a chest tube insertion in two patients out of 15 after fiducial implantation owing to pneumothorax [27]. Whyte et al reported three patients with pneumothoraces; two were managed expectantly but one required chest tube placement [28].…”

CyberKnife: review of first 1,000 cases at a dedicated therapy center

“…In the Munich Center 35 patients harbouring small (<50 cc) lung tumors have undergone this procedure using 24 Gy in a single session procedure ( Table 4). The preliminary results are very promising and no significant treatment-related toxicity was found [3]. However, follow-up is too short for definitive assessment of clinical outcome (Fig.…”

“…Radiosurgical applications are evolving from standard neurosurgical indications (i.e., acoustic neurinomas, meningiomas, brain metastases, etc.) to extracranial indications [3]. Treating tumors of the lung, liver, kidney, etc., is particularly challenging because these organs are subject to respiratory movements.…”

Accelerated Partial Breast Irradiation: Using the CyberKnife as the Radiation Delivery Platform in the Treatment of Early Breast Cancer

“…Based on the correlation between the position of the LEDs and the internal fiducials, a correlation model predicts the location of the tumor throughout the respiratory cycle and moves the treatment beam to remain on target with the treatment volume. The system has been shown in end-to-end phantom tests to be accurate to within 1.5 mm (Muacevic et al, 2007; Wong et al, 2007). …”