ESTRO 2024 - Abstract Book

S891

Clinical - CNS

ESTRO 2024

Conclusion:

Re- irradiation of recurrent BM is safe, with no G≥3 acute toxicity and radionecrosis in less than 1% of re -treated lesions, in our experience. It was effective with initial responses in 86.7% of pts. The re-irradiation in a median of 5 fractions likely accounted for the good toxicity result; however a longer follow-up, and a prospective study are needed to confirm these results.

Keywords: brain metastasis, re-irradiation, SRT

2130

Poster Discussion

Comparison of fractionated SRS treatment quality amongst multiple stereotactic delivery platforms

Alonso La Rosa 1 , Rupesh Kotecha 1,2,3 , D Jay D. Wieczorek 1,2 , Yongsook C. Lee 1,2 , Kathryn E. Mittauer 1,2 , Stephanie Key 4 , Nema Bassiri-Gharb 1 , Sreenija Yarlagadda 1 , Tugce Kutuk 1 , Chuanyu Zhou 5 , Michael W. McDermott 6,3 , Minesh P. Mehta 1,2 , Alonso N. Gutierrez 1,2 , Ranjini Tolakanahalli 1,2 1 Miami Cancer Institute. Baptist Health South Florida, Radiation Oncology, Miami, USA. 2 Herbert Wertheim College of Medicine, Florida International University, Radiation Oncology, Miami, USA. 3 Herbert Wertheim College of Medicine, Florida International University, Translational Medicine, Miami, USA. 4 ZAP Surgical Systems, Inc, Sales and Marketing, San Carlos, USA. 5 ZAP Surgical Systems, Inc, Software Engineering, San Carlos, USA. 6 Miami Cancer Institute. Baptist Health South Florida, Neurosurgery, Miami, USA

Purpose/Objective:

Various specialized intracranial FSRS platforms are available but a contemporary comprehensive cross-platform comparison of standardized dosimetric objectives for large brain metastases (BMs) and/or post-operative BMs cavities treated with FSRS has not been performed. The objective of this study is to compare pre-specified dosimetric planning metrics for FSRS treatment plans generated using Gamma Knife® (GK), CyberKnife® (CK), Volumetric Modulated Arc Therapy (VMAT), MR-guided Linac (MRL), and ZAP-X for large intracranial targets (metastases and resection cavities).

Material/Methods:

Twenty patients (10 with large intact BMs treated to 27 Gy in 3 fractions and 10 resection cavities treated to 30 Gy in 5 fractions) treated on GK with FSRS were re-planned with CK, VMAT, MRL intensity-modulated radiation therapy (IMRT), and ZAP-X. For intact brain metastases, the gross tumor volumes (GTVs) were defined on enhancing disease; for postoperative cavities, the GTVs were defined as the resection cavities and a 2 mm expansion was used to generate the clinical target volumes (CTVs) Plans were optimized not to exceed organ-at-risk (OAR) dose constraints and achieve a minimum target coverage (TC) of ≥ 99.5% while maximizing the Paddick Conformity Index (PCI) and