Araştırma Çıktıları

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Author: search.filters.author.Gungor, GorkemSubject: search.filters.subject.sbrt

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    Magnetic Resonance Imaging-Guided Online Adaptive Lattice Stereotactic Body Radiotherapy in Voluminous Liver Metastasis: Two Case Reports
    (CUREUS INC, 2022-01-01) Dincer, Neris; Ugurluer, Gamze; Korkmaz, Latif; Serkizyan, Anatolia; Atalar, Banu; Gungor, Gorkem; Ozyar, Enis
    Lattice Radiotherapy (LRT) is a technique in which heterogeneous doses are delivered to the target so large tumors can have optimal doses of radiation without compromising healthy tissue sparing. lb date, case reports and case series documented its application for bulky tumors mainly in the pelvic region. LRT not only provides dosimetric advantages but also promotes tumor control by triggering some radiobiological and immunological pathways. We report two cases of giant liver metastases for whom other treatment options were not suitable. We treated both patients with Magnetic Resonance Image-Guided Radiotherapy (MRgRT) with online adaptive LRT (OALRT) technique. Adaptive plans were generated before each fraction. Tumors were observed to have regressed interfractionally so the location and number of spheres were adapted to tumor size and daily anatomy of the surrounding organs at risk (OAR). Both patients had good treatment compliance without any Grade 3+ side effects. They are both under follow-up and report improvement. By reporting the first application of OALRT by using MRgRT in liver metastases, we show that MRgRT is a promising modality for LRT technique with better target and OAR visualization as well as online adaptive planning before each fraction according to the daily anatomy of the patient.
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    Magnetic Resonance Image-Guided Hypofractionated Ablative Radiation Therapy for Hepatocellular Carcinoma With Tumor Thrombus Extending to the Right Atrium
    (CUREUS INC, 2022-01-01) Dincer, Neris; Ugurluer, Gamze; Mustafayev, Teuta Zoto; Gungor, Gorkem; Atalar, Banu; Guven, Koray; Ozyar, Enis
    Hepatocellular carcinoma (HCC) presenting with tumor thrombus and inferior vena cave (IVC)/right atrium (RA) infringement point to an advanced-stage disease that is deemed inoperable. Stereotactic body radiotherapy is an emerging treatment option for this group of patients with promising outcomes in recent studies that are comparable to conventional treatment methods, namely, transarterial chemoembolization and transarterial radioembolization. Here, we report a case of HCC with RA extension through the IVC. The patient was referred to our clinic for treatment options, and he was found suitable for magnetic resonance imaging-guided radiotherapy (MRgRT). We treated the patient with MRgRT in five fractions to a total dose of 40 Gray. The tumor was tracked during the treatment sessions, and adaptive treatment planning was performed before each fraction. The patient tolerated the treatment well with no acute grade 3-4 toxicities. The last follow-up showed that the patient had a complete biochemical response and is now a candidate for an orthotopic liver transplant. To our knowledge, this report is the first to document the MRgRT treatment of an HCC with TT and RA extension. MRgRT is safe and feasible for this patient group and can be an effective bridging therapy for liver transplants.
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    First 500 Fractions Delivered with a Magnetic Resonance-guided Radiotherapy System: Initial Experience
    (CUREUS INC, 2019-01-01) Sahin, Bilgehan; Mustafayev, Teuta Zoto; Gungor, Gorkem; Aydin, Gokhan; Yapici, Bulent; Atalar, Banu; Ozyar, Enis
    Objectives Improved soft-tissue visualization, afforded by magnetic resonance imaging integrated into a radiation therapy linear accelerator-based radiation delivery system (MR-linac) promises improved image-guidance. The availability of MR-imaging can facilitate on-table adaptive radiation planning and enable real-time intra-fraction imaging with beam gating without additional exposure to radiation. However, the novel use of magnetic resonance-guided radiation therapy (MRgRT) in the field of radiation oncology also potentially poses challenges for routine clinical implementation. Herein the early experience of a single institution, implementing the first MRgRT system in the country is reported. We aim to describe the workflow and to characterize the clinical utility and feasibility of routine use of an MR-linac system. Methods The ViewRay MRIdian MR-linac system consists of a split-magnet 0.35 T MR-imaging scanner with a double focused multi-leaf collimator (MLC) equipped 6MV linear accelerator. Unique to the system are the control console integrated on-table adaptive radiation therapy (oART) planning capabilities as well as automated beam gating based on real-time intra-fraction MR imaging. From the first day of clinical implementation, oART was performed according to physicians' discretion when medically indicated. All fractions were delivered under real-time imaging with soft tissue-based automated beam gating with individualized gating boundary settings. Patients actively assisted in breath-hold beam gating with the help of custom designed prismatic glasses allowing sight of a computer monitor mounted on the back wall just behind the MRI system bore. Patient demographics and treatment experience, indications for MRgRT including diagnosis and disease site, radiation dose prescribed and fractionation scheme, utilization of oART, respiratory gating settings, as well as duration of each treatment phase were analyzed. Results Between September 2018 and May 2019, 72 patients with 84 tumor sites were treated with MRgRT in 500 total fractions. Median patient age was 66 years (range: 28-83 years). Among 84 tumor sites, the most frequently treated regions were upper abdominal and pelvic (n = 36, 43\% and n = 29, 34\%, respectively). The most common diagnosis was prostate cancer, with 14 patients treated. In 69 patients (93.2\%) oART was used at least once during a treatment course. Twenty-nine targets (43.1\%) with significant breathing-related motion were treated in breath-hold with patient visual feedback. Median prescribed dose was 36.25 Gy (range: 24-70 Gy) in median five fractions (range: 3-28 fractions). A gating boundary of 3 mm around a gating region of interest (gROI) was most commonly used (range: 3-5 mm) with 95\% of the gROI (range: 93-97\%) required to be within the gating boundary for the beam to automatically engage. Mean total treatment time was 47 min (range: 21-125 min) and mean beam-on time was 16.7 min (range: 6-62 min). Conclusions MRgRT afforded by an MR-linac system has been successfully implemented into routine clinical use at our institution as the first system of its kind in Turkey. While the overall number of patients treated and fractions delivered is still limited, we have demonstrated the feasibility of both on-table adaptive radiation therapy as well as automated real-time beam gating on a daily basis in acceptable time schedules.