Outcomes for children with relapsed ependymoma are poor. Re-irradiation is a potentially viable salvage option in these patients. Data were reviewed for 12 patients (median age 5.6 years) with relapsed ependymoma who received fractionated stereotactic radiosurgery (fSRS) following maximal surgical resection from 1995 to 2012. Four patients experienced a second recurrence, including 2 in-field and 2 distant failures. Median time to second recurrence (32 months) was significantly longer than time to first recurrence (24 months) (p = 0.008). Three-year local control was 89 %, and median event free survival from fSRS was 3.4 years. Radiation necrosis was observed in 6 patients, 3 who were symptomatic. In conclusion, fSRS offers durable response with a tolerable toxicity profile in children with recurrent EPN.
Electron paramagnetic resonance spectroscopy is used to observe hydroxyl radicals produced by an atmospheric pressure nonthermal plasma device at distances greater than 1 m from the discharge. The plasma device is an indirect treatment setup with closed loop airflow and hydrogen peroxide additives that is effective in deactivating bacteria on time scales of seconds. The generation of the detected hydroxyl radicals is shown to occur in secondary chemical processes near the point of delivery of the plasma treated air stream. The production of hydroxyl radicals is correlated with humidity of the air stream and ability to lyse bacterial membranes. The overall mechanisms of bacteria inactivation are found to be a combinatorial effect of effluent species. The results indicate the feasibility of selective plasma induced free radical delivery for biomedical applications even in the case of short-lived species like the hydroxyl radical.
Radiation necrosis is a well-described toxicity following radiation therapy in the brain. There is little data regarding the incidence of radiation necrosis in pediatric patients. We retrospectively reviewed our experience with 101 children with solid brain tumors. Radiation necrosis was diagnosed by examination of magnetic resonance imaging. Median follow-up for all patients was 13 months (range 3-51). Radiation necrosis occurred in 5% (5/101) of cases with a median time to onset of 1.2 months. In three of these children, the child was symptomatic, requiring management with steroids and bevacizumab. Radiation necrosis did not correlate with the administration of chemotherapy, age at treatment, or planning treatment volume. Our experience with pediatric patients treated with radiotherapy for solid brain tumor suggests that children may have an increased likelihood to develop radiation necrosis compared to adults.
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