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Radiosurgery for Mesial Temporal Lobe Epilepsy Following ROSE Trial Guidelines - A Planning Comparison Between Gamma Knife, Eclipse and Brainlab

G Narayanasamy

G Narayanasamy1*, D Cousins2 , W Garner2 , J Liu2 , X Zhang1 , S Morrill1 , S Maraboyina1 , L Peacock1 , F Xia1 , J Penagaricano1 , (1) University of Arkansas for Medical Sciences, Little Rock, AR, (2) University of Arkansas for Medical Sciences, Little Rock, AR


SU-I-GPD-T-629 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To generate stereotactic radiosurgery (SRS) plans in Gamma Knife (GK) for treatment of epilepsy and for comparison against highly non-coplanar beam arrangement in Eclipse and dynamic conformal arc plan in Brainlab.

Methods: 20 GK plans were produced on MRI scans for Rx=24 Gy to 50% isodose line based on Radiosurgery or Open Surgery for Epilepsy (ROSE) trial guidelines. The recommended maximum dose to brain stem (BS), optic apparatus (OA) were 10 Gy and 8 Gy, respectively for a prescription isodose volume (PIV) within 5.5 – 7.5 cc. Following transfer of contours from MRI to CT using rigid registration, CT based planning was performed using 2 methods: 20 highly non-coplanar conformal beam arrangement in Eclipse TPS and 5-dynamic conformal arc plan in Brainlab’s iPlan. The latter 2 methods were normalized to ensure PIV meet the ROSE trial criteria by utilizing 1 mm MLC margin outside the target.

Results: The volumes of the target were in the range of 4.0 – 7.7 cc. The mean ± SD of PIV, target coverage (%) were 6.6±0.9 cc, 82±3 % in GK; 7.1±0.3 cc, 79±9 % in Eclipse; and 7±0.4 cc, 70±10 % in Brainlab plans. The volumes of the PIV were significantly lower in GK than Eclipse and Brainlab (p-values<0.05). The coverage is significantly higher in GK than Brainlab (p-value<0.05), however did not display superiority over Eclipse (p-value=0.05). The mean of maximum doses to BS, OA were 10, 7.9 Gy in GK; 6.2, 4.5 Gy in Eclipse; and 6.3, 5.6 Gy in Brainlab plan. Both Eclipse and Brainlab based plans had significantly lower maximum doses to BS, OA (p-value<0.001).

Conclusion: All 3 SRS planning techniques for epilepsy adhered to the ROSE trial recommendations; GK plans had higher target coverage and significantly lower PIV.

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