Browsing by Author "Arslan, Gungor"

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Cardiac angiosarcoma treated with 1.5 Tesla MR-guided adaptive stereotactic body radiotherapy-Case report and review of the literature
(2022) Noyan, Asli; Yavas, Guler; Arslan, Gungor; Yavas, Cagdas; Onal, Cem; 0000-0002-2742-9021; 36027835; D-5195-2014
Introduction: Cardiac angiosarcoma is a very rare disease. As a result of their nonspecific presentation symptoms, and the lack of consensus in treatment, caution should be taken in both diagnosis and treatment. The role of radiotherapy (RT) is debatable due to the continuous movement of the heart, which makes it difficult to safely deliver high radiation doses to the target volume.Presentation of case: The case of a 16-year-old boy with cardiac angiosarcoma that recurred one year after surgery and was treated with chemotherapy is presented. The patient received high field 1.5-Tesla (magnetic resonance) MR-Linac treatment in 5 fractions with a dosage of 25 Gy to the tumor bed and 30 Gy to the recurrent nodules using the simultaneous integrated boost technique. The patient tolerated the treatment well and had stable disease two months later. Discussion: MR-guided radiotherapy, particularly in the case of cardiac malignancies, allows for direct tumor visualization with high soft tissue image resolution capacity. Furthermore, modern RT techniques allow for the full therapeutic window to be used by achieving superior dose distributions, allowing for dose escalation stra-tegies with tolerable toxicity rates.Conclusion: Magnetic resonance guided RT allows direct visualization of the target during treatment delivery, allowing for higher-dose administration with less damage to healthy tissue near the tumor. This treatment strategy is a viable option in selected patients with cardiac angiosarcoma.
Comment on Hunt et al, "Feasibility of magnetic resonance guided radiotherapy for the treatment of bladder cancer"
(2021) Yavas, Guler; Yavas, Cagdas; Arslan, Gungor; Onal, Cem; 33912694
Dosimetric comparison of vaginal vault brachytherapy vs applicator-guided stereotactic body radiotherapy with volumetric modulated arc therapy and helical tomotherapy for endometrium cancer patients
(2019) Yildirim, Berna Akkus; Dolek, Yemliha; Guler, Ozan Cem; Arslan, Gungor; Onal, Cem; 0000-0001-6908-3412; 0000-0001-6661-4185; 0000-0002-2742-9021; 30551844; AAC-5654-2020; D-5195-2014
We performed this dosimetric study to compare a nonstandard volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) techniques with high-dose rate (HDR) brachytherapy (BRT) plan of vaginal vault in patients with postoperative endometrial cancer (EC). Twelve postoperative patients with early stage EC were included in this study. Three plans were performed for each patient; dosimetric and radiobiological comparisons were made using dose-volume histograms and equivalent dose for determining the planning target volume (PTV) coverages in brachytherapy and external beam radiotherapy, and organs-at-risk (OARs) doses between three different delivery techniques. All the plans achieved adequate dose coverage for PTV; however, the VMAT plan yielded better dose conformity, and the HT plan showed better homogeneity for target volume. With respect to the OARs, the bladder D-2cc was significantly lower in the BRT plan than in the VMAT and HT plans, with the highest bladder D-2cc value being observed in the HT plan. However, no difference was observed in the rectum D-2cc of the three plans. Other major advantages of the BRT plan over the VMAT and HT plans were the relatively lower body integral doses and femoral head doses as well as the fact that the integral doses were significantly lower in the BRT plan than in the VMAT and HT plans. This is the first dosimetric comparison of vaginal vault treatment for EC with BRT, VMAT, and HT plans. Our analyses showed the feasibility of stereotactic body radiotherapy technique as an alternative to HDR-BRT for postoperative management of EC patients. (C) 2018 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.
Effects of Setup Errors on Dose Distribution for Tangential Wedge Field and Field-in-Field Techniques During Breast Irradiation
(2014) Sonmez, Aydan; Onal, Cem; Sonmez, Serhat; Arslan, Gungor; Parlak, Cem; Topkan, Erkan; Yavuz, Melek
This study is aimed to evaluate the effects of setup errors on dose distribution for target volume and healthy tissue within the irradiated volume and also critical surrounding organs for breast radiotherapy (RT) using both the tangential field and the field-in-field (FIF) technique. Ten patients with breast cancer were enrolled. For each patients two plans were generated; tangential field plan and FIF-plan. The setup errors were simulated for a series of displacements of +/- 5 mm and +/- 10 mm in superior-inferior (x-axis), medial-lateral (y-axis), and anterior-posterior (z-axis) directions and dose volume comparisons were made both between and within groups. The most prominent changes were observed in setup errors at z-axis. In wedge plan, 10-mm setup error at the +z axis caused a significant decrease in tumor coverage compared with the plan with no setup error (96.5% vs. 99.2%; p= 0.01). The 5 and 10 mm setup errors at the +z-axis resulted in significantly higher healthy tissue doses in wedge plans compared with FIF plans. The setup errors along z-axis had a significant effect on the dose distribution for target volume and also to the lungs. The setup error in the isocenter should be kept strictly below 5 mm.
Incidental testicular doses during volumetric-modulated arc radiotherapy in prostate cancer patients
(2020) Onal, Cem; Bozca, Recep; Dolek, Yemliha; Guler, Ozan Cem; Arslan, Gungor; 0000-0001-6908-3412; 0000-0002-2742-9021; 32125635; AAC-5654-2020; D-5195-2014
Purpose To compare the incidental testicular doses during volumetric-modulated arc therapy (VMAT) in patients receiving prostate-only and pelvic lymphatic irradiation. Materials and methods Testicular doses in 40 intermediate- and high-risk prostate cancer patients were determined on treatment planning system (TPS) using the VMAT technique at 6 MV. Scattered testicular doses were also measured by MOSFET detectors placed on testis surface. The testicular doses of patients treated with prostate-only and pelvic field irradiation were compared. Results The median testicular doses measured per 200 cGy fraction by TPS and MOSFET detectors were 1.7 cGy (0.7-4.1 cGy) and 4.8 cGy (3.6-8.8 cGy), respectively. The TPS doses and MOSFET readings showed a significant strong correlation (Pearson r = 0.848, p < 0.001). The testicular doses measured by TPS (1.34 +/- 0.36 cGy vs. 2.60 +/- 0.95 cGy; p < 0.001) and MOSFET (4.52 +/- 0.64 cGy vs. 6.56 +/- 1.23 cGy; p < 0.001) were significantly lower in patients with prostate-only irradiation than in those with pelvic field irradiation. The mean cumulative scattered dose for prostate-only field delivering 78 Gy was 1.8 Gy and that for pelvic field irradiation was 2.6 Gy, consistent with the reported findings. Conclusions The patients with prostate-only irradiation received lower testicular doses than those with additional pelvic field irradiation possibly due to the increased scattered doses in large field irradiation using the VMAT technique. The clinical response to increased incidental testicular doses due to pelvic field irradiation remains unknown, and it warrants further investigation.