ESTRO 38 Abstract book

S694 ESTRO 38

procedures, which included surgery (12 patients), repeat gamma knife alone (5 patients), or a combination of repeat gamma-knife and surgery (3 patients). Of the patients receiving additional treatments, 14 experienced pain relief at their most recent follow up. Conclusion Complete pain control following GK treatment for TG neuralgia at one year was found to be 56% in our cohort. It is difficult to discern the actual control rate from the 1999-2006 cohort due to significant loss to follow-up, perhaps due to symptom resolution. 66% of patients in our cohort required additional procedures for pain management, including surgery and repeat GK. Future directions include reviewing more recent cases from 2006- 2018, which may have improved follow up and documentation due to implementation of the electronic medical record. EP-1263 Hippocampal avoidance in WBRT for Metastases – Comparative Neurocognitive and Dosimetric Assessment V. Pareek 1 , R. Bhalavat 1 , M. Chandra 1 1 Jupiter Hospital, Radiation Oncology, Mumbai, India Purpose or Objective Hippocampus is associated with formation and storage of new memory and irradiation of the same during whole brain radiotherapy in brain metastases leads to decline in the neurocognitive function. Recent advancements in radiation delivery in form of IMRT, Hippocampal avoidance has been made possible. We analyze feasibility of hippocampal sparing and associated neurocognitive and Between June 2016 to December 2017, 125 patients diagnosed radiologically and clinically with brain metastases were included in the study. Mini Mental State Examination (MMSE) and quality of life assessment with EORTC BN20 questionnaire were assessed along with dosimetry. Patients were assessed at baseline and followed by at 1, 3 and 6 months respectively. Factors were compared with the historical group with relation to quality of life especially neurocognitive functioning. Wilcoxon test for multiple comparisons was calculated to detect significant differences in global QoL scores. Dose received in WBRT was 30Gy in 10 fractions in both arms with boost of 9Gy in single metastases. Results Median age of accrued 125 patients was 48 years. Median D100% and Dmax to contralateral hippocampus was 7.1Gy and 16.7Gy. With IMRT, the doses to other critical structures were reduced. Patients treated with IMRT were found to have achieved desired dose constraints to hippocampus. Assessment of neurocognitive function between two groups, there was no difference at 1 month after treatment, however, difference was seen at 3 and 6 months favouring hippocampal avoidance. No difference noted in other aspects of quality of life between two groups. No severe toxicities (Grade 3 and 4) were noted in either group. Median survival in the HA-WBRT arm was found to be 10.1 months. Conclusion Conformal avoidance of hippocampus during WBRT is associated with improved neurocognitive function and quality of life. IMRT has found to provide better dosimetric outcomes in HA-WBRT dosimetric assessment. Material and Methods

(acceptable deviation per RTOG 0631, prefer >90%) in all cases. Contours were based on the International Spine Radiosurgery Consortium Consensus. Objectives are based on RTOG 0631 protocol. OAR objectives for single fraction are: spinal cord V10Gy<0.35 cc, V14Gy<0.03 cc, partial cord V10Gy<10% and cauda equina V16Gy<0.03cc. Dose spillage objectives for single fraction are volume of 105% isodose out of PTV <3 cc (V105% out of PTV <3cc), V115% out of PTV 0.0 cc, and conformity index < 1.5. OAR objectives for three fractions are based on NRG BR001 protocol: spinal cord V22.5Gy<0.03cc, V13Gy<1.2cc, cauda equina V25.5Gy<0.03cc and V21.9Gy<5cc. Dose spillage objectives were the same as the single fraction cases. Linac-based MRI guided SABR plans were generated for the Co-60 MRI guided SABR cases using vendor supplied software Results Co-60 . Organ at risk (OAR) objectives were met in all cases. However, dose spillage for Co-60 plans would often be considered unacceptable by RTOG 0631 protocol: median V105% out of PTV: 23.7 cc (11.4 cc - 33 cc) and median V115% out of PTV: 2.2 cc (0.0 cc – 8.2 cc). Treatment was delivered considering that this dose spillage was mostly into para-spinal soft tissues and not into OARs. No adverse effects have been observed, and all cases had excellent visualization of spinal anatomy with real-time patient motion tracking and gating. Linac . All OAR objectives were met in all cases. Does spillage for linac plans were either per RTOG 0631 protocol or acceptable deviation in all cases. Median V105% out of PTV: 1.35cc (0.18 cc – 3.0 cc) with V115% out of PTV 0.0cc. Conclusion Co-60 MRI-guided SABR achieves an adequate target coverage and OAR sparing for spinal osseous metastases. Treatments are safe, well tolerated, and excellent setup and real-time guidance of treatment are observed. However, dose spillage guidelines were not achieved in many Co-60 delivered cases due to MLC width and cobalt penumbra. However, dose spillage guidelines can be met with newer generation linac-MRI systems. MRI guidance can improve safety and dose escalation for spine SABR given clear visualization of the cord and other structures during treatment. EP-1262 Use of Gamma Knife Radiosurgery for Treatment of Trigeminal Neuralgia D. Fabian 1 , J. Palmer 2 1 The Ohio State University, Radiation Oncology, Columbus, USA ; 2 Palmer, Radiation Oncology, Columbus, USA Purpose or Objective Gamma Knife radiosurgery (GK) has been shown to relieve symptoms of trigeminal neuralgia (TN). Success rates have been reported to range between 70-90% at a follow up of 19-75 months. Our objective was to evaluate the success rate of GK for TN treatment in our institution and to evaluate the need for additional procedures. Our hypothesis was that the need for additional treatments would be high. Material and Methods We identified 50 cases of refractory TG treated with GK at our institution from 1999-2006. These patients were retrospectively chart-reviewed and assessed for subjective pain control and need for medical management. Average GK dose was 38 Gy to the 50% isodose; the median dose was 40 Gy to the 50% isodose. Of these 50 cases, only 30 patients had adequate follow up at 1 year. Results Of the patients with adequate one-year follow up, 17 reported adequate control of their pain following the procedure (56%). 10 (33%) patients reported control at 2 years post first gamma knife treatment and 6 patients (13%) reported control at 5 years post first gamma knife treatment. 20 patients were reported to have additional

Electronic Poster: Clinical track: Haematology

EP-1264 Patterns of care for orbital MALToma in Korea throughout 2016: a multicenter cross-sectional study