Optimizing immobilization, margins, and imaging for lung stereotactic body radiation therapy

Abstract

The simultaneous advancement of technologies for the delivery of precisely targeted radiation therapy and the paradigm shift to substantial hypofractionation have led to significant improvements in the treatment of early stage non-small cell lung cancer (ES-NSCLC). Stereotactic body radiation therapy (SBRT) has become a well-established option for the treatment of ES-NSCLC and is now becoming widely available within the radiation oncology community. Implementation of this technique, however, requires highly accurate target delineation, thorough evaluation of tumor motion, and improved on-board imaging at the time of treatment for patient alignment, each of which is critical for successful tumor control and mitigation of risks to normal tissues. In this article, we review updates and issues related to immobilization and image guidance for SBRT in the treatment of ES-NSCLC.

Keywords: Radiation; image guidance; margins; motion management; non-small cell lung cancer (NSCLC).

Figure 1

Lung motion with and without abdominal compression. Axial (A,B) and coronal (C,D) CT images of a patient with a right lower lobe stage I non-small cell lung cancer planned for SBRT with contours after CT simulation of GTV (red), iGTV (blue) and PTV (green). (A,C) CT simulation without motion mitigation; (B,D) CT simulation with abdominal compression. SBRT, stereotactic body radiation therapy; GTV, gross tumor volume; iGTV, internal GTV; PTV, planning target volume; CT, computed tomography.