A Comparative Analysis of Helical Tomotherapy Planning with Active Versus Total Bone Marrow Sparing Using Dual-Energy Computed Tomography

Purpose: This study aims to compare helical tomotherapy (HT) plans using active bone marrow (ABM) sparing contouring versus traditional bone marrow (BM) sparing contouring using dual-energy computed tomography (DECT) in the treatment of gynecologic (GYN) cancers. The goal is to evaluate the effects of using ABM contours in optimization on organs at risk (OAR) and planning target volumes (PTVs). Methods: The study involved creating HT plans for GYN cancer patients, utilizing both ABM and BM contouring techniques. DECT was used to distinguish between active and inactive bone marrow. Dosimetric comparisons were made between BM and ABM sparing plans. Statistical analyses were completed to evaluate the differences between planning with TBM and ABM sparing contours. Results: The results indicated that planning with ABM contours consistently resulted in lower doses to bone marrow, particularly V40, with statistically significant reductions observed. The effect sizes for these reductions were moderate. For other organs at risk, ABM plans showed minimal differences compared to TBM plans. Both plans achieved comparable target coverage, with no significant differences in PTV doses. Conclusions: ABM sparing contouring using DECT in HT planning for GYN cancers effectively reduces bone marrow dose and potential hematologic toxicity without compromising target coverage. Future research should focus on larger cohorts and the incorporation of advanced imaging modalities to further refine ABM delineation and validate these findings. Additionally, clinical side effects of ABM sparing plans should be observed.