Automated Treatment Planning for Lymphocyte Preservation Radiotherapy: Sparing Blood-Bearing Organs Linked to Survival In NSCLC
Abstract
Purpose
To identify blood-bearing organs whose mean blood dose is significantly associated with OS in non-small cell lung cancer (NSCLC), and to evaluate the feasibility of sparing these organs during treatment planning.
Methods
A retrospective analysis was performed on 155 NSCLC patients treated with concurrent chemoradiotherapy. Hematological Dose (HEDOS) framework was used to estimate blood dose to 19 organs, delineated with an in-house AI auto-segmentation algorithm. Mean blood dose from the seven highest contributing organs was tested for association to OS using Cox proportional hazards regression. A lymphocyte depletion and recovery model was fitted to median absolute lymphocyte counts (ALC) at pre-treatment, nadir, 60 and 120 days, estimating the lymphocyte radiosensitivity and recovery rate. A 10-patient replanning study was conducted introducing additional dose constraints for aorta and pulmonary arteries (PA). Both clinical and blood dose-optimized plans were generated by a clinically deployed automated planning system, developed in-house. Predicted ALCs for both plans were estimated using the lymphocyte depletion and recovery model.
Results
The median OS (N=155) was 1.8 years with interquartile range (IQR) of 2.9 years. Mean blood dose to lung, heart, aorta and PA significantly predicted worse OS (Hazard ratios=1.1-5.3; p-values=0.003-0.02). In the blood-dose optimized plans (N=10), mean doses to aorta and PA were reduced by a median (IQR) of 3.0 (2.3) Gy and 3.6 (4.3) Gy, respectively. Target coverage and all clinical dose constraints were satisfied. The lymphocyte sensitivity and recovery were estimated as 0.36 Gy-1 and 0.0075 day-1, respectively. Blood dose-optimized plans consistently yielded higher predicted ALCs than original clinical plans, with maximum lymphocyte sparing of approximately 8%.
Conclusion
Mean blood dose to lung, heart, aorta and PA significantly predicted worse OS in NSCLC patients. Introducing aorta and PA dose constraints was feasible without compromising clinical standards and may result in improved lymphocyte preservation and treatment outcomes.