Dosimetric Results for Stereotactic Radiosurgery Using a Self-Shielded Gyroscopic Radiosurgery System for Meningioma Patients
Abstract
Purpose
This study presents dosimetric results for stereotactic radiosurgery (SRS) using a self-shielded gyroscopic radiosurgery system for meningioma patients.
Methods
Eighteen single-lesion meningioma patients, who were treated using Zap-X® Gyroscopic Radiosurgery® platform, were selected and divided into two groups (Group A [thirteen patients]: 25 Gy in 5 fractions, fractionated SRS (FSRS); Group B [five patients]: 15 Gy in a single fraction, SRS). Clinical plans performed in the Zap-X treatment planning system and independent dose calculations performed using an in-house tool and patient-specific quality assurance (PSQA) performed using SRS MapCHECK were reviewed and analyzed for each group.
Results
For Group A, mean age (range) was 60 years (35 years - 80 years) and mean planning target volume (PTV) (range) was 4.78 cc (2.10 cc - 9.38 cc). Mean (range) PTV coverage, prescribed isodose line, Paddick conformity index, gradient index, number of isocenters, number of beams, delivery time estimate per fraction and PSQA gamma passing rate were 99.5% (99.5% - 99.6%), 53.5% (50.1% - 61.3%), 0.89 (0.83 - 0.93), 2.64 (2.54 - 2.88), 11.8 (5 - 19), 208.5 (91 - 332), 43.6 min (24.5 min - 61.0 min) and 95.0% (91.5% - 98.4%), respectively. For Group B, corresponding values were 70 years (62 years - 75 years), 1.12 cc (0.77 cc - 1.99 cc), 99.5% (99.5% - 99.5%), 56.4% (50.6% - 62.8%), 0.89 (0.85 - 0.93), 2.95 (2.63 - 3.22), 7.2 (5 - 9), 102.4 (81 - 132), 33.9 min (27.3 min - 38.9 min) and 95.3% (91.1% - 100.0%). For all beams in both groups, independent dose calculations were <±0.02% of treatment planning system dose calculations.
Conclusion
Our experience with SRS and FSRS using the Zap-X system for meningioma patients demonstrated that treatment plans met our institutional planning goals and were concordant with independent dose calculations and PSQA.