Room: AAPM ePoster Library
To fully automate the treatment planning and delivery process of hippocampal-sparing whole brain irradiation (HS-WBRT) by combining HyperArc technology (HyperArc™ Varian Medical System) and RapidPlan knowledge-based planning model (RapidPlan™ Varian Medical System).
HyperArc (HA) technology provides automated settings for the location of isocenter, a standard set of non-coplanar beams (full arc at couch 0, half arcs at couch 3150, 450 and 2700) and collimator angles, and allows automated delivery on the machine. The publicly available RapidPlan (RP) model for WBRT-HS automatically generates optimization objectives based on dose-volume histogram (DVH) estimates.
Nine patients previously treated with HS-WBRT were re-planned using HA geometry and RP optimization objectives (HA-RP). Planning target volumes (PTV) and organs at risk (OAR) outlined following NRG-CC001 guidelines were used during optimization and no other planning pseudo-structures were created. HA-RP plans were compared with conventional RP plans.
All HA-RP plans were generated in < 30 minutes and achieved target coverage, dose homogeneity and OAR constraints “per protocol” with no plan being in the “variation acceptable” range. In general, HA-RP performed better (mean ± St Dev) for target dose homogeneity (D2% minus D98% divided by prescription dose) compared to RP plans (0.14±0.02 vs 0.19±0.01, p< 0.01). The volume of PTV receiving the prescription dose was comparable between HA-RP and RP plans (95.8±0.8% vs 95.3±1.0%, p=0.16). Additionally, the hippocampi's maximum dose was equivalent between the two planning modalities (12.9±0.7 vs 12.5±0.6, p=0.14), while the D100% dose was slightly higher, but not clinically significant for the HA-RP plans vs. RP plans (7.96±0.19 vs 7.77±25, p=0.03).
HA technology combined with RP model provides fully automated planning and delivery for HS-WBRT. The auto-generated plans together with automated treatment delivery increase planning consistency and efficiency and ultimately improves patient care by delivering a quality complex treatment safely in a shorter time.