Pioneering Change in Radiotherapy With Biological Adaptive Radiotherapy for Lung Volumetric Modulated Radiotherapy (VMAT) Patients

Aims: To introduce a Biological Adaptive Radiotherapy (BART) framework that incorporates biological effects into adaptive planning, quantify the impact of a short intrafraction interruption on biologically effective dose (BED) in stage III non-small cell lung cancer treated with volumetric modulated arc therapy (VMAT), and evaluate a compensation strategy designed to restore target BED while respecting organs-at-risk (OAR) constraints. Methods: We analysed lung non-small cell cancer patients with stage III treated using VMAT with two full arcs. A microdosimetric kinetic model (MKM) was used to calculate BED reductions caused by a 120-minute interruption after the first arc. Compensation plans were generated by converting deviations in biological dose into physical dose adjustments, which were optimised using a treatment planning system (TPS). Dose–volume histograms (DVHs) and other metrics were compared for plans with and without interruptions and after BART compensation. Results: Interruption An interruption caused BED reductions in planning target volume, with the dose difference of the D_98% and D_2% differences of 15.7%-16.5% and 5.2%-14.5%, respectively. For a normal lung, volume differences at 5 Gy (V_5Gy) and 20 Gy (V_20Gy) ranged from 0.7% to 2.2% and 0.3% to 4.7%, respectively. With dose compensation, the dose differences reduced to 0.8%-1.4% for the D_98% and 1.4%-8.3% for the D_2%. The difference of the V_5Gy and V_20Gy also decreased to 1.0%-4.1% and 0.4%-2.6%, respectively. Spinal cord dose constraints were met across all plans. Conclusion: The BART framework effectively compensates for BED reductions due to short-term treatment interruptions, preserving therapeutic efficacy and adhering to organ at risk (OAR) constraints. This innovative approach represents a transformative advancement in adaptive radiation therapy by integrating biological considerations, enhancing treatment precision and personalisation.