(Sunday, 7/14/2019) 1:00 PM - 2:00 PM
Room: Stars at Night Ballroom 4
Purpose: This study aims to generate and compare 4 SRS planning techniques for treatment of Mesial temporal lobe epilepsy (MTLE) under Radiosurgery or Open Surgery for Epilepsy (ROSE) guidelines using GammaKnife (GK), Eclipse non-coplanar conformal (NCC), Brainlab dynamic conformal arcs (DCA), and Eclipse VMAT plan.
Methods: Twenty GK plans with prescription dose 24 Gy obeyed ROSE trial recommended maximum doses to brainstem, optic apparatus (OA) of 10 and 8 Gy, respectively and prescription isodose volume (PIV) within 5.5 – 7.5 cc. Eclipse plan using 20 highly NCC beams, Brainlab iPlan plan using 5 DCA, and Eclipse VMAT plan with 4 arcs were generated by experienced planners. Volume of 12Gy to normal brain (V12) was evaluated. Wilcoxon signed rank test was used to study statistical significance at 0.05 threshold.
Results: The volumes of the target were in the range 4.0 – 7.4 cc. Mean ± SD of conformity index (CI) and gradient index (GI) were 1.2±0.1 and 3.4±0.3 in GK, 1.3±0.2 and 3.7±0.4 in Eclipse NCC, 1.3±0.3 and 4.4±0.6 in Brainlab DCA, and 1.3±0.1 and 3.8±0.2 in Eclipse VMAT plans. PIV and V12 (associated with neurotoxicity) was significantly lower in GK than Eclipse NCC, Brainlab DCA, and Eclipse VMAT plans (p-values<0.002). Highest maximum doses to brainstem and OA were 10.9 and 8.7 Gy in GK, 10.3 and 7.8 Gy in Eclipse NCC, 10.4 and 8.2 Gy in Brainlab DCA, 9.9 and 7.8 Gy in Eclipse VMAT plans. All 3 linac based plans had significantly lower maximum doses to BS, OA than GK (p-value<0.001).
Conclusion: All 4 SRS planning techniques adhered to the ROSE trial recommendations in producing clinically deliverable plans for MTLE. GK plans had significantly lower PIV and V12, but suffered from higher maximum dose to brainstem and optic apparatus.
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