Application of respiratory motion management technology for patients with lung cancer treated with stereotactic body radiotherapy (Review)

Abstract

Respiratory-induced tumor motion is a major obstacle in the precise delivery of stereotactic body radiotherapy (SBRT) for lung cancer, often leading to geometric uncertainties, insufficient tumor coverage and increased radiation-induced toxicity such as pneumonitis, esophagitis and rib fractures. The present review systematically assesses motion management techniques used in lung SBRT, synthesizing evidence from 352 high-quality clinical studies published between 2000 and 2024. Selected studies included patients with non-small cell lung cancer treated exclusively with SBRT which incorporated strategies such as deep inspiration breath-hold, abdominal compression, respiratory gating and real-time tumor tracking, and often integrated with image guidance technologies such as 4DCT, cone beam CT and MRI. These techniques demonstrated notable reductions in planning target volume margins and normal tissue dose, leading to improved local control and lower toxicity rates, particularly in tumors with large motion amplitudes or proximity to critical structures. Despite these benefits, implementation remains variable due to patient-specific challenges, technical complexity and institutional resource differences. The present review highlights the clinical applications and limitations of each strategy, and proposes a decision-making framework to guide clinicians in selecting the most appropriate motion management strategy based on tumor characteristics, motion amplitude and patient-specific factors. The integration of respiratory motion management with advanced imaging is essential for optimizing therapeutic outcomes and safety in lung SBRT.

Keywords: non-small cell lung cancer; radiation pneumonitis; respiratory motion management; stereotactic body radiotherapy.

Figure 1.

Schematic illustration of four respiratory motion management strategies in lung stereotactic body radiotherapy. (A) Breath-holding (deep inspiration breath-hold): Patient holds a deep inspiration to stabilize tumor position by expanding the lungs and lowering the diaphragm. (B) Abdominal compression: External pressure limits diaphragmatic movement to reduce tumor motion. (C) Respiratory gating: Radiation is delivered only during selected phases of the breathing cycle, guided by internal or external surrogates. (D) Real-time tumor tracking: Tumor position is continuously monitored and the beam dynamically follows the moving target.