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    Dosimetric analysis of SIB whole brain radiotherapy planning: Comparison of coplanar VMAT and tomotherapy techniques
    (Wiley, 2025) Pepele, Eda Kaya; Temelli, Oztun
    Background Radiotherapy techniques have advanced significantly over the past few decades. Whole-brain radiotherapy combined with a simultaneous integrated boost (WBRT+SIB) is increasingly used to treat limited brain metastases. Purpose To retrospectively compare helical tomotherapy and coplanar volumetric modulated arc therapy (VMAT) for WBRT with a SIB-WBRT in patients with multiple brain metastases. Additionally, it emphasizes the importance of selecting appropriate evaluation indices when comparing SIB plans. Materials and methods Fifteen patients with 2- 3 metastatic lesions were retrospectively analyzed in this study. Treatment planning was performed using TomoHD and eclipse planning systems for tomotherapy and VMAT, respectively. Dose-volume histograms were used to assess the doses delivered to the target volumes and organs at risk (OARs). Quantitative metrics, including the homogeneity index (HI), conformity index (CI), and plan quality index (PQI), were used for the evaluation. Results Tomotherapy yielded significantly higher D98% values for both the planning target volume (PTV) WB and PTV_met compared with VMAT (p < 0.05). It also provided lower D-max and D-mean values for the lenses and eyes (p < 0.001 and p < 0.02, respectively). Tomotherapy was superior in terms of PTV whole-brain CI and PTV_met HI and CI (p < 0.05). However, no significant difference was observed in the PQI values between the techniques (p > 0.05). Conclusion Both tomotherapy and VMAT achieved acceptable target volumes and OAR doses in SIB applications. Tomotherapy showed advantages in terms of dose conformity and critical organ sparing. Moreover, this study highlights the impact of selecting appropriate evaluation indices on interpreting plan quality, particularly for complex treatment approaches such as SIB.
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    Sitagliptin Alleviates Radiation-Induced Kidney and Testis Degeneration in Rats
    (Multidisciplinary Digital Publishing Institute (MDPI), 2025) Celik, Huseyin; Temelli, Oztun; Ozhan, Onural; Taslidere, Elif; Dogru, Feyzi
    Background: Radiation-induced tissue degeneration is the most important side effect of radiotherapy. Sitagliptin with its anti-inflammatory and antioxidant capacity was tested in alleviating the radiation-induced cellular degeneration in kidney and testis tissues. Methods: Wistar albino rats were divided into four groups as control, radiation (RT), radiation + sitagliptin (RT + SGT), and sitagliptin + radiation (SGT + RT). The RT group received 8 Gy radiation. Sitagliptin was applied per os at a 10 mg/kg dose for 14 days to the SGT groups either after or before radiation. Results: Radiation induced marked oxidative stress in kidney and testis tissues, whereas sitagliptin partially restored several antioxidant parameters in the kidney and reduced MDA levels in the testis. Histologically, radiation caused degenerative changes in the renal tubules and glomerulus and the testicular seminiferous tubules, while sitagliptin treatment attenuated these changes in both organs. Caspase-3 expression increased significantly after radiation treatment in the kidney without substantial improvement by sitagliptin; however, VEGF expression, which was markedly reduced by radiation in both tissues, was restored in sitagliptin-treated groups. FGF expression suppressed in all irradiated groups as compared to the control with no significant differences among them. Conclusions: Overall, the results indicated that sitagliptin can be used to attenuate the degenerative effects induced by radiation. Sitagliptin use after radiation as compared to the before use showed significantly better results especially in the kidney tissue. © 2025 by the authors.