Assessment of Physical Lung Dose-Volume Parameters in Patients Receiving Split Course Radiation Therapy for Advanced-Stage Non Small Cell Lung Cancer: Dosimetric Effect of Active Breathing Control and Clinical Implications: Analytical Research, Case-Control

ABS TRACT Objective: Active breathing control (ABC) system ser- ves as a viable technique for the management of respiratory motion by providing reproducible breath-holding. Herein, we assess physical lung dose-volume parameters of V20 (total lung volume receiving ≥ 20 Gy) and mean total lung dose (MLD) in a series of patients receiving split course radiation therapy (SCRT) for advanced-stage non-small cell lung cancer (NSCLC) with the incorporation of the ABC system. Material and Methods: A series of 22 patients receiving ABC-guided SCRT for advanced-stage NSCLC were evaluated for physical lung dose-volume parameters of V20 and MLD. Two different radiation therapy plans have been generated for every patient with and without the incorpora- tion of the ABC system to investigate the dosimetric impact. Results: Mean V20 and MLD were 32.3% and 2,104 cGy, respectively at free- breathing. Mean V20 and MLD were 24.7% and 1,697 cGy, respectively with the incorporation of the ABC system. The decrease in V20 and MLD was 23.53% and 19.34%, respectively. Conclusion: Our study shows improved normal lung tissue sparing by incorporation of ABC system in SCRT of advanced-stage NSCLC. The reduction in V20 and MLD may have clinical implications. Improved normal lung tissue sparing by use of the ABC system may result in an improved toxicity profile of radiation delivery and thereby enable dose escalation in selected patients. Admittedly, clinical follow-up of patients should be performed to elucidate clinical reflections of dosimetric gains achieved by the ABC system.