Stereotactic Radiotherapy in lung cancer using respiratory gating: technical applications, the role of TSRM and the potential of AI

Abstract

Stereotactic Body Radiation Therapy (SBRT) has emerged as a standard treatment option for early-stage lung cancer patients who are medically inoperable or at high surgical risk. The effectiveness of SBRT relies on the delivery of high ablative doses with sub-millimetric precision; however, respiratory-induced tumor motion remains a major challenge, potentially compromising target coverage and increasing toxicity to surrounding organs at risk (OARs). Respiratory gating techniques have been developed to mitigate these limitations by synchronizing radiation delivery with specific phases of the breathing cycle. This thesis aims to analyze the role of SBRT in lung neoplasms with a particular focus on respiratory gating, highlighting its technical applications, clinical and dosimetric benefits, the pivotal role of the Radiology Technician and the emerging contribution of Artificial Intelligence in treatment planning and delivery. A review of international guidelines (ESTRO, ASTRO, AAPM) was conducted, focusing on SBRT protocols for lung tumors, respiratory motion management strategies, and technological advancements. Technical aspects of phase-based, amplitude-based, breath-hold, and real-time adaptive gating were examined, along with their impact on treatment accuracy. Special attention was given to the operational responsibilities of the TSRM during simulation, patient positioning, 4D-CT acquisition, treatment delivery, and quality assurance.
Respiratory gating significantly reduces target volume margins and irradiation of healthy lung tissue, leading to improved dosimetric conformity and lower rates of radiation-induced toxicity, particularly pneumonitis. Clinical evidence demonstrates high local control rates and favorable outcomes in appropriately selected patients. AI-based systems, including real-time tumor tracking and automated contouring, further enhance precision and workflow efficiency, supporting adaptive treatment strategies.
SBRT with respiratory gating represents a model of precision radiotherapy in lung cancer management. The integration of advanced motion management and AI technologies reinforces the central role of the TSRM as a highly specialized professional, combining technical expertise, patient-centered care, and multidisciplinary collaboration to optimize treatment safety and effectiveness.