Image-Guided Robotic Stereotactic Radiation Therapy with Fiducial-Free Tumor Tracking for Lung Cancer

Abstract

PurposeStereotactic body radiation therapy (SBRT) for early-stage lung cancer can be achieved with several methods: respiratory gating, body frame, or real-time target and motion tracking. Two target tracking methods are currently available with the CyberKnife® System: the first one, fiducial tracking, requires the use of radio-opaque markers implanted near or inside the tumor, while the other, Xsight® Lung Tracking System, (XLTS) is fiducial-free. With XLTS, targeting is synchronized directly with target motion, which occurs due to respiration. While the former method (fiducial tracking) is well documented, the clinical relevance of the latter (tracking without fiducials) has never been well described to this date.Patients and MethodsA study was performed at our department for each patient treated for lung cancer with CyberKnife using XLTS. Selection criteria were: primary or recurring T1 or T2 stage non-small-cell lung cancer (NSCLC) with 15–60 mm tumor size. Initial staging included CT-Scan and FDG-PET.ResultsFifty-one patients not amenable to surgery were treated with XLTS. Median follow-up was 15 months (range, 5–30 months). Median tumor size was 24 mm (range, 15–60 mm). Median total dose was 60 Gy (36–60 Gy) in three fractions. Actuarial overall survival was 85.5% (95% CI = 74.5–96%) at 1 year and 79.4% (95% CI = 64–94.8%) at 2 years. Actuarial local control rate was 92% (95% CI = 84–99%) at one1 year and 86% (95% CI = 75–97%) at 2 years.ConclusionLocal control and overall survival rates were similar to previous reports that used fiducials for tumor tracking. Toxicity was lower than most studies since tumor tracking did not require fiducial implantion. This fiducial-free method for respiratory motion tracking is a valid option for the most fragile patients.

Feasibility study of robotic hypofractionated lung radiotherapy by individualized internal target volume and XSight Spine Tracking: A preliminary dosimetric evaluation

“…[3] Both target tracking methods could be combined with the Synchrony real-time respiratory tracking system (RTS). [4] The technical basis of the RTS is a correlation model between an external breathing signal and internal target positions determined from stereoscopic x-ray imaging of the implanted fiducials or the tumor combined with the compensation of that motion by the robotic arm.…”

Evaluation of a cone beam computed tomography geometry for image guided small animal irradiation

“…To mimic human radiotherapy situation, we need deliver focal radiation to the tumor target while sparing normal tissues. One example requiring precision focal irradiation is to model the radiation induced lung injury by mimicking clinical stereotactic radiotherapy often delivered with CyberKnife non-coplanar radiation beams (Bibault, et al, 2012, Gibbs, et al, 2010). Another example is to investigate the synergetic effect of combining radiotherapy and immunotherapy (Zeng et al, 2013, Burnette et al, 2013).…”

Endobronchial treatment of peripheral tumors: ongoing development and perspectives

“…Nevertheless, there are alternative choices of tracking respiration which can reduce the indication for fiducial markers. The CYBERKNIFE ® (Accuray, Sunnyvale, CA, USA) allows to not using fiducial with Xsight Spine Tracking System (18)(19)(20). Other machines may require using fiducial markers to reduce the radiotherapy field.…”