No abstract

-The exploitation of bistatic Doppler measurements for multistatic tracking is considered. It is found through simulation, that, while the velocity estimation of the standard extended Kalman filter is improved in monostatic situations and multistatic situations where measurement errors are small, a degradation in performance is observed in multistatic situations where the measurement errors are realistically large. A bistatic modification to the alternate EKF of Bizup and Brown [9] is proposed as a means of exploiting bistatic Doppler measurements in realistic multistatic situations.Simulation results confirm that the proposed filter outperforms the standard EKF and can produce significantly improved target velocity estimates when Doppler measurements are exploited in multistatic applications.

AIMS Limited data exists on outcomes following SRS for brainstem metastases (BSM). The purpose of this audit was to explore the use of SRS using Cyberknife for BSM at a single centre; reporting rates of toxicity and survival outcomes. METHOD Patients undergoing SRS for BSM from 2013 to 2021 were identified from a prospective database. Clinical characteristics were collected including; gender, age, histology and KPS. The use of previous WBRT, the volume and the dose delivered to the BSM were also recorded. All target volumes were peer reviewed by a neuro-radiologist. RESULTS 41 patients with a BSM were identified. The median age was 62 years (range 35-78). Histology was lung 15 (36.6%), breast 13 (31.7%) and other 13(31.7%). The median brainstem target volume was 0.36cc (range 0.01 – 5.63cc). 32 patients had single fraction (dose range 14.5 to 18Gy) and 9 patients had 3 fractions (dose range 17-24Gy). 7 patients had previous WBRT. Median overall survival was 242 days (range 19-1213). A radiological response or stable disease was seen in 26 out of 30 patients with post SRS imaging available for review. 2 patients developed a 6th nerve palsy. 12 patients required a prolonged course of dexamethasone. No statistically significant relationship was observed between patient age, brainstem lesion size or fractionation and the need for prolonged use of dexamethasone but there was a trend with lung cancer patients requiring prolonged dexamethasone (p=0.06). CONCLUSION Brainstem SRS is viable option with an acceptable late toxicity profile. Updated information on survival and local control will be presented.

No abstract