Abstract
While Volumetric Modulated Arc Therapy (VMAT) has become the standard ofcare for complex radiotherapy treatment planning, manual optimization remains a
highly complex and time consuming process. HyperArc addresses these limitations
as a highly automated, specialized extension of modern VMAT. Utilizing a single
isocenter technique and pre-optimized, non-coplanar arc trajectories, HyperArc stan-dardizes the planning workflow to maximize target dose conformity while minimizing
exposure to surrounding organs at risk. Based on these geometric and automated ad-vantages, we hypothesized that HyperArc would yield superior dosimetric outcomes
compared to VMAT in two complex clinical scenarios: multilevel head and neck can-cer, and whole-brain radiotherapy with hippocampal sparing.
To evaluate this, a comparative dosimetric analysis was performed across twopatient cohorts. In the multilevel head and neck cohort (n=2), VMAT was found
to be superior at maintaining standard clinical goals, achieving 56 out of 64 goals
compared to 51 for HyperArc. Conversely, in the whole brain with hippocampal
sparing cohort (n=4), HyperArc successfully outperformed VMAT, meeting 28 out of
29 clinical objectives versus VMAT’s 20 out of 29. A subsequent follow-up analysis
of the whole brain with hippocampus sparing cohort revealed that, upon normaliza-tion, dose gradients within the hippocampal region were dosimetrically comparable
between the two modalities 1,154.8 cGy for HyperArc vs. 1183.35 cGy for VMAT.Ultimately, however, HyperArc provided an improved, standardized workflow that
significantly increased planning e!ciency and reproducibility. Specifically, HyperArc
required an average of fewer optimization objectives at 8.25 compared to VMAT’s
22.75, which minimizes manual planner intervention. HyperArc for this set of plans
also used fewer monitor units at 733.4 MU compared to 834.4 MU for VMAT; this
translates to a faster treatment delivery times and can ultimately reduce scatter.