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This work represents a comparative study of gas‐phase parameters and reactive‐ion etching kinetics for Si and Si and SiO2 in CF4 + O2 and C6F12O + O2 plasmas. An interest to the C6F12O gas is because it combines the low global warming potential (low environmental impact) and weakly studied dry etching performance. It was shown that the investigated gas systems showed similar effects of processing conditions on electron‐ and ion‐related plasma parameters as well as on the densities of F and O atoms. Etching experiments showed identical behaviors of Si and SiO2 etching rates as well as very similar SiO2/Si etching selectivities. The notable feature of the C6F12O + O2 plasma is only the systematically lower absolute etching rates that correlate with lower in F atom densities. [ABSTRACT FROM AUTHOR]

High-grade transformation of low-grade gliomas has long been a poor prognostic factor during therapy. In 2016, the World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS) adopted isocitrate dehydrogenase (IDH) mutation status in the classification of diffuse astrocytomas. The 2021 classification denoted glioblastomas as IDH-wildtype and graded IDH-mutant astrocytomas as 2, 3, or 4. Gemistocytic morphology, a large proportion of residual tumor, the patient's age, and recurrence after radiotherapy were previously mentioned as risk factors for high-grade transformation of low-grade gliomas. We report a 34-year-old male patient initially diagnosed with IDH-mutant grade 2 astrocytoma according to the 2021 WHO classification of CNS tumors. As the first surgical resection achieved gross total resection on postoperative MRI, no adjuvant therapy was given and regular follow-up was planned. On 1-year follow-up MRI, two new enhancing nodular lesions appeared at the ipsilateral brain parenchyma abutting the surgical resection cavity. Salvage craniotomy achieved gross total resection, and the pathologic diagnosis was IDH-mutant WHO grade 4 astrocytoma. We describe this tumor in terms of the previous WHO classification to evaluate the risk of high-grade transformation and discuss possible risk factors leading to high-grade transformation of low-grade astrocytoma., Competing Interests: Ho-Shin Gwak, the Editor-in-Chief of Brain Tumor Research and Treatment, was not involved in the editorial evaluation or decision to publish this article. All remaining authors have declared no conflicts of interest., (Copyright © 2024 The Korean Brain Tumor Society, The Korean Society for Neuro-Oncology, and The Korean Society for Pediatric Neuro-Oncology.)