Room: Exhibit Hall
Purpose: To report our beta testing results on a new volumetric modulated arc therapy (VMAT) treatment planning module from BrainLab called â€œElements Cranial SRS.â€? This automated treatment planning module was specifically designed for complex cranial stereotactic radiosurgery (SRS) cases.
Methods: We evaluated Elements Cranial SRS via a retrospective analysis of previously treated intensity modulated radiosurgery (IMRS) and dynamic conformal arc therapy (DCAT) plans against Elements VMAT plans. Nine previously treated patients, planned by either DCAT or IMRS, including three acoustic neuroma cases, three pituitary adenoma cases, and three post-operative cavity cases were selected for retrospective re-planning. Minimally acceptable planning target volume (PTV) prescription dose coverage was 95%. The new VMAT plans were compared to these plans through conformity indices at 100%, 50%, and 25% of the prescription dose, as well as percent difference in ICRU defined near-maximum dose to six selected organs at risk (OARs). Total monitor units (MUs) and number of couch angles were evaluated for delivery efficiency.
Results: A significant improvement to the optic chiasm (p<0.05) was observed while no significant differences (p>0.05) in near maximum dose were seen for five of the six OARs investigated in comparing 2 arc VMAT plans with original plans DCAT and IMRS plans. Significant improvements in CI100 (p<0.05) were observed in VMAT plans while little statistical difference was found between VMAT plans and original plans for CI25 and CI50. These improvements were obtained with fewer MUs and reduced number of couch angles from an average of five to two in VMAT plans.
Conclusion: Elements Cranial SRS offers a fast and straightforward treatment planning experience and yields consistent results among planners with different experience levels. The plan quality surpasses existing DCAT and IMRS with more efficient treatment delivery, better high dose conformity, and no statistical difference in OAR avoidance for cranial SRS.
Funding Support, Disclosures, and Conflict of Interest: This research is supported by BrainLab through the research contract VUMC60978.