Browsing by Author "Sahin, Sevim"

Now showing 1 - 2 of 2

Citation - WoS: 4
Effect of Multileaf Collimator Leaf Position Error Determined by Picket Fence Test on Gamma Index Value in Patient-Specific Quality Assurance of Volumetric-Modulated Arc Therapy Plans
(Springernature, 2021) Ceylan, Cemile; Inal, Serpil Yondem; Senol, Elif; Yilmaz, Berrin; Sahin, Sevim; Elektrik-elektronik Mühendisliği Bölümü
Aim The correlation between the MLC QA (IBA Dosimetry, Germany) results of the picket fence test created with intentional errors and the patient's quality assurance (QA) evaluation was investigated to assess the impact of multileaf collimator (MLC) positioning error on patient QA. Materials and methods The picket fence, including error-free and intentional MLC errors, defined in Bank In, Bank Out, and Bank Both were analyzed using MLC QA. The QA of 15 plans consisting of stereotactic radiosurgery (SRS), stereotactic body radiotherapy (SBRT), and conventionally fractionated volumetric-modulated arc therapy (VMAT) acquired with electronic portal imaging devices (EPID) was evaluated in the presence of error-free and MLC errors. The QA of plans were analyzed with 2%/2 mm and 3%/3 mm criteria. Results The passing rates of the picket fence test were 97%, 92%, 91%, and 87% for error-free and intentional errors. The criterion of 3%/3 mm wasn't able to detect an MLC error for either SRS/SBRT or conventionally fractionated VMAT. The criterion of 2%/2mm was more sensitive to detect MLC error for the conventionally fractionated VMAT than SRS/SBRT. While only two of SBRT plans had <90%, four of conventionally fractionated VMAT plans had a <90% passing rate. Conclusion We found that the systematic MLC positioning errors defined with picket fence have a smaller but measurable impact on SRS/SBRT than the VMAT plan for a conventionally fractionated and relatively complex plan such as head and neck and endometrium cases.
The Therapeutic Role of Ginseng in Promoting Hippocampal Neurogenesis and Ameliorating Cognitive Function Following Whole Brain Radiotherapy in Rats
(Springer/Plenum Publishers, 2025) Sahin, Sevim; Bayindir, Nihan; Ertas, Busra; Ceylan, Cemile; Elibol, Birsen; Ozkan, Alper; Sener, Goksel
Whole-brain radiotherapy (WBRT) is a prevalent technique for managing multiple intracranial metastases, however, the cognitive damage in long-term survivors due to WBTR is a critical concern that impacts patients' quality of life. Panax ginseng, a bioactive compound recognized for its neuroprotective benefits, also enhances cognitive functions, including memory and learning. This study aims to examine the potential protective effects of Panax ginseng supplementation on cognitive dysfunction and the levels of neurogenesis-related proteins in the hippocampus of rats that underwent WBRT, which was delivered as 3 fractions of 6 Gy (total dose 18 Gy) using a linear accelerator. Thirty-six male Sprague-Dawley rats were divided into three groups: radiation, ginseng treatment, and control. After 60 days of Panax ginseng administration (100 mg/kg), behavior tests (Morris water maze and novel object recognition) were performed, followed by western blot analysis of the hippocampus. Results indicated that Panax ginseng supplementation ameliorated radiation-induced cognitive impairments. Additionally, western blot analyses revealed that Panax ginseng promoted neuronal recovery and neuroplasticity processes in the hippocampus, simultaneously exhibiting a neuroprotective mechanism by reducing apoptosis and neurotoxicity markers. Panax ginseng ameliorates cognitive dysfunction after WBRT by enhancing neurogenesis and diminishing cell death in the hippocampus.