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 D98% and D2% differences of 15.7%-16.5% and 5.2%-14.5%, respectively. For a normal lung, volume differences at 5 Gy (V5Gy) and 20 Gy (V20Gy) 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 D98% and 1.4%-8.3% for the D2%. The difference of the V5Gy and V20Gy 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.