Room: Exhibit Hall
Purpose: Edema following stereotactic-radiosurgery (SRS) is a known phenomenon. But, there is limited data correlating dosimetric predictors to edema risk. A retrospective study is performed to investigate the impact of dosimetric parameters on edema risk in meningioma patients receiving SRS.
Methods: A cohort of 54 patients with 61 meningioma lesions treated with single-fraction (n=46) or fractionated (n=8) SRS at our institution, from 2010-2017, were retrospectively analyzed for dosimetric-factors potentially predictive of edema risk. The average patient age was 58(Â±11) years. The development of edema was tracked pre- and three yearsâ€™ post-radiation treatment. The dose-volume histograms for target, normal-tissue, tissue (i.e. target and normal-tissue) and brain-planning target volume (brain-PTV) were exported from the delivered plans created in iPlan TPS. The brain-PTV was contoured on the same CT-dataset to estimate dose effects. The evaluated dose-metrics were V12Gy and V10Gy for organs-at-risk and volume, D99, D0.1cc for tumor.
Results: Non-symptomatic edema (NSE) and symptomatic edema (SE) respectively occurred in 11% and 18% patients. The Brain-PTV dose-metrics (V12Gy, V10Gy) were (5.0Â±13, 7.6Â±17)cc for no-edema (NE), (12Â±27, 15Â±32)cc for SE and (6.5Â±7.3, 11Â±9.5)cc for NSE. The normal-tissue dose-metrics (V12Gy, V10Gy) were (10Â±20, 6.5Â±15)cc for no-edema, (27Â±60, 20Â±47)cc for SE and (15Â±16, 10Â±12)cc for NSE. The evaluated tumor dose-metrics such as volume, D99 and D1cc were (3Â±4cc, 13.5Â±2.7Gy, 16.5Â±4.0Gy) for NE, (6.7Â±7.6cc, 13Â±3.7Gy, 17Â±6.4Gy) for SE and (6.1Â±5.5cc, 14Â±3.1Gy, 18Â±4.0Gy) for NSE. While a relatively larger volume of normal-tissue received dose>10Gy in edema patients vs. no-edema patients, this was non-significant (p>0.1 with ANOVA).
Conclusion: Among patients who developed edema after SRS for meningioma, the brain and normal-tissue volume>10-12Gy and the volume of tumor was relatively greater than patients who did not develop edema, although these differences were non-significant. Similar studies on a larger patient population will be useful to guide future patients receiving SRS for meningiomas.
Not Applicable / None Entered.