ESTRO 2025 - Abstract Book

S692

Clinical - CNS

ESTRO 2025

Conclusion: These preliminary results provide valuable prospective data in an area where the published literature is dominated by retrospective studies. We have modelled the relationship of BED 10 and local control, which remains significant independently of tumour size. Our results are similar to those reported in the literature[4], lending weight to our data-set as representative of the wider BM-SRS population. The SAFER study is recruiting 375 patients for 2-years of follow-up.

Keywords: brain metastases, stereotactic radiosurgery

References: 1. Liu, Q., X. Tong, and J. Wang, Management of brain metastases: history and the present. Chin Neurosurg J, 2019. 5 : p. 1. 2. Linskey, M.E., et al., The role of stereotactic radiosurgery in the management of patients with newly diagnosed brain metastases: a systematic review and evidence-based clinical practice guideline. J Neurooncol, 2010. 96 (1): p. 45-68. 3. Redmond, K.J., et al., Tumor Control Probability of Radiosurgery and Fractionated Stereotactic Radiosurgery for Brain Metastases. Int J Radiat Oncol Biol Phys, 2021. 110 (1): p. 53-67. 4. Loo, M., et al., Dose-Response Effect and Dose-Toxicity in Stereotactic Radiotherapy for Brain Metastases: A Review. Cancers (Basel), 2021. 13 (23).

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Digital Poster Features of PET/CT with fluoroethyltyrosine interpretation after proton radiation therapy of patients with IDH wildtype glioblastoma Elena Gromova 1 , Nikita Kataev 2 , Nikolay Vorobyov 2,3 , Daniil Susin 1 , Marina Linnik 2 , Nataliia Martynova 2 , Anastasiya Panasyuk 2 , Natalia Berezina 4 , Kirill Suprun 5,6 1 Radiology, MIBS, Saint Petersburg, Russian Federation. 2 Proton Therapy, MIBS, Saint Petersburg, Russian Federation. 3 Chair of oncology, SPbU, Saint Petersburg, Russian Federation. 4 Administrative, MIBS, Saint Petersburg, Russian Federation. 5 Surgery, MIBS, Saint Petersburg, Russian Federation. 6 Surgery, SPbU, Saint Petersburg, Russian Federation Purpose/Objective: To identify the features of PET/CT with fluoroethyltyrosine in patients with IDH wildtype glioblastoma who received proton therapy as part of adjuvant chemoradiation treatment. Material/Methods: We evaluated 17 PET/CT c FET studies in 13 patients 3-18 (median 5.5, SD 12) months after proton therapy. PET/CT was performed at the decision of the neuro-oncologist for differential diagnosis of radionecrosis and tumor progression. PET-CT was performed according to the standard protocol: scanning 20 min after RFP injection, scanning time 20 min. The evaluation was performed by semi-quantitative method, with TBTmax calculation, as well as with comparison with MRI data and irradiation plans. Radiation therapy was delivered to all patients with a scanning pencil beam using 2 5/13 (38%) or 3 8/13 (62%) fields. In 10/13 (76.9%) cases, at least one of the fields was not coplanar. Two radiation therapy regimens were used: 45 Gray for 15 fractions and 60 Gray for 30 fractions (112.5-120.0 BED) Cases of RFP hyperfixation foci outside the initial volume of high (D95%) dose were considered separately - the zones of their occurrence, correlations between the necrosis site and the direction of proton therapy fields were determined separately.