Initial Evaluation of Krylov Optimizer for ZAP-X Stereotactic Radiosurgery
Abstract
Purpose
A new optimizer is planned for the ZAP-X stereotactic radiosurgery (SRS) treatment planning system (TPS) upgrade version 1012, utilizing a Krylov algorithm. In this study, ZAP-X TPS 1012 beta version is evaluated against the current TPS version 1011 along with Edge SRS on a single plan for dosimetric comparison.
Methods
A single Brain Metastases plan was selected for this study, consisting of six targets. Three plans were created using 1012, 1011, and single isocenter Edge SRS. All plans were optimized under the same constraints to reach ≥ 99% coverage on the target for 24 Gy in 3 fractions. The plans were compared with each other for gross target volume (GTV) coverage, conformity index (CI), and gradient index (GI), and for dose constraints on organs-at-risks (OARs) as recommended by Timmerman 2021.
Results
The average GTV CI for 1012 was 1.22 ± 0.13, for 1011 was 1.22 ± 0.12, and for Edge was 1.25 ± 0.17. The average GTV GI for 1012 was 3.3 ± 0.8, for 1011 was 3.3 ± 0.7, and for Edge was 4.5 ± 1.3. The average OAR dose to 0.035 cm3 volume for 1012 was 89 ± 17 cm3, for 1011 was 90 ± 50 cm3, and for Edge was 90 ± 20 cm3. The Brain volume (Brain - GTV) receiving 1200 cGy (V1200cGy) for 1012 was 10.07 cm3, for 1011 was 24.61 cm3, and for Edge was 19.18 cm3. The treatment time for 1012 was 60 minutes, for 1011 was 50 minutes, and for Edge was 30 minutes.
Conclusion
ZAP-X TPS version 1012 demonstrates an improvement in plan quality compared to 1011. Plans made by 1012 may reduce Brain V1200cGy significantly, with possible longer treatment time compared to 1011 and single isocenter Edge.