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Öğe Cardiotoxicity after the lymphoma(Istanbul Tip Fakultesi, 2022) Özen, Alaattin; Fayda, MerdanSUMMARY Radiotherapy (RT) is the cornerstone component of the current successful treatment of Hodgkin lymphoma (HL). Although RT has been used alone to cure in most patients in decades, combined modality regimes are preferred in most HL patients currently, besides early-stage lymphocyte predominance HL and for selected patients with classical HL who have contraindications to chemotherapy. Although clas-sic RT fields, doses, and techniques have fundamentally changed over the years, the heart is still an organ at risk, and patients with radiation-induced cardiovascular complications are increased in the long term. In this paper, we aimed to review literature about radiation-induced cardiotoxicity in lymphoma patients treated with mediastinal RT. © 2022.Öğe Clinical utility of a 1.5 T magnetic resonance imaging-guided linear accelerator during conventionally fractionated and hypofractionated prostate cancer radiotherapy(PMC, 2022) Türkkan, Görkem; Bilici, Nazlı; Sertel, Hüseyin; Keşküş, Yavuz; Alkaya, Sercan; Özkırım, Müge; Fayda, MerdanPurpose: To report our initial experience with 1.5 T magnetic resonance imaging (MRI) linear accelerator (LINAC) in prostate cancer radiotherapy in terms of its use in a radiation oncology clinic. Methods: The medical records of 14 prostate cancer patients treated with MRI-guided radiotherapy were retrospectively evaluated. The fraction time, adapt-to-position (ATP):adapt-to-shape (ATS) usage rate, machine-associated treatment interruption rate, median gamma pass rate, the percentage of planning target volume receiving at least 95% of the prescription dose coverage value of each ATS fraction, the effect of the learning curve on the fraction time and radiation-related acute gastrointestinal and genitourinary toxicities were evaluated. Results: Fourteen patients have completed their treatment receiving a total of 375 fractions. Six patients (42%) were treated with the moderately hypofractionated regimen, five patients (36%) with conventionally fractionated, and three patients (22%) with the ultra-hypofractionated radiotherapy regimens. The ATP : ATS usage ratio was 3:372. The median fraction time was 46 min (range, 24-81 min). For the 3%/3 mm criterion, median gamma pass rate was 99.4% (range, 94.6-100%). Machine-related treatment interruptions were observed in 11 (2.9%) of 375 fractions, but this interruption rate decreased from 4.1% to 0.8%, after an upgrade. Three patients (22%) had gastrointestinal and five patients (36%) had genitourinary toxicity. No ?grade 3 toxicity was observed. Conclusion: 1.5 T MRI-LINAC device could be used as a conventional LINAC device, when the conditions of the radiotherapy center are appropriate. MRI-guided prostate radiotherapy is safe and feasible, and high-quality studies with a larger number of patients and long-term results are needed to better evaluate this new technology.Öğe Computed tomography-guided optimization of needle insertion for combined intracavitary/interstitial brachytherapy with utrecht applicator in locally advanced cervical cancer(Elsevier Inc., 2021) Tambas, Makbule; Tavlı, Büşra; Bilici, Nazlı; Dizman, Aysen; Sertel, Hüseyin; Fayda, MerdanPurpose: There are no international guidelines for optimal needle insertion during interstitial intracavitary brachytherapy (IS-ICBT) for cervical cancer. We aimed to investigate the clinical feasibility and added value of computed tomography (CT) guidance to optimize needle insertion in IS-ICBT using the Utrecht applicator and to evaluate needle shifts. Methods and Materials: We enrolled 24 patients who were treated with IS-BT. Two CT scans each were performed for every patient: 1) after applicator insertion without needles (CTpreneedle); 2) after needle insertion (CTpostneedle). In addition to magnetic resonance imaging (MRI) after external-beam radiotherapy, CTpreneedle was used to determine optimal needle locations and insertion lengths based on applicator and organs at risk positioning on the day of treatment; CTpostneedle was used for IS-ICBT planning. The needle-channel axis was used as a reference to determine needle-shift evolution. Results: A total of 266 interstitial needles were inserted in 76 of 93 BT fractions with high intra- and interpatient variations in the number of inserted needles. Based on CTpreneedle findings, needle insertion was avoided in nine, four, two, and two patients at the first, second, third, and fourth fractions, respectively. The unloaded needle frequency was 4%. Average needle contribution to total dwell time was 37.2±19.2%. Shifting was observed in 68% of the needles (mean shift 2.0±2.3 mm), mostly in the posterior direction, and in needles with a larger insertion length. Needle reinsertion was not needed in any patient. No complication due to needle insertion was observed, except for minor vaginal bleeding in one patient after needle removal.Öğe Development of independent mu/treatment time verification algorithm for non-imrt treatment planning: a clinical experience(Amer Inst Physics, 2018) Tatlı, Hamza; Yücel, Derya; Yılmaz, Sercan; Fayda, MerdanThe aim of this study is to develop an algorithm for independent MU/treatment time (TT) verification for non-IMRT treatment plans, as a part of QA program to ensure treatment delivery accuracy. Two radiotherapy delivery units and their treatment planning systems (TPS) were commissioned in Liv Hospital Radiation Medicine Center, Tbilisi, Georgia. Beam data were collected according to vendors' collection guidelines, and AAPM reports recommendations, and processed by Microsoft Excel during in-house algorithm development. The algorithm is designed and optimized for calculating SSD and SAD treatment plans, based on AAPM TG114 dose calculation recommendations, coded and embedded in MS Excel spreadsheet, as a preliminary verification algorithm (VA). Treatment verification plans were created by TPSs based on IAEA TRS 430 recommendations, also calculated by VA, and point measurements were collected by solid water phantom, and compared. Study showed that, in-house VA can be used for non-IMRT plans MU/TT verifications.Öğe Dosimetric comparison of volumetric-modulated arc therapy and dynamic conformal arc therapy in three-fraction single-isocenter stereotactic radiosurgery for multiple brain metastases(KARE PUBL, 2022) Türkkan, Görkem; Bilici, Nazlı; Sertel, Hüseyin; Tavlı, Büşra; Özkırım, Müge; Fayda, MerdanAbstract OBJECTIVE The objective of the study was to compare single-isocenter volumetric-modulated arc therapy (VMAT) and dynamic conformal arc therapy (DCAT) techniques in patients who received multifraction stereotactic radiosurgery (SRS) for multiple brain metastases. METHODS Twenty-one patients who were treated with a radiation dose of 27 Gy in three fractions were replanned. Roth VMAT and DCAT plans with single isocenter were obtained for each patient. Plan quality indices, cumulative monitor unit (MU) values, maximum dose for organs at risk, and mean dose, V19.6(Gy), and V23.1(Gy) for healthy brain tissue were compared. RESULTS The conformity index (11=0.0002), gradient index (p=0.003), maximum dose for brainstem (p=0.016) and mean dose (p=0.00007), V19.6(Gy) (p=0.00006), and V23.1(Gy) (p=0.00006) values for healthy brain tissue were significantly superior in the VMAT technique, compared to DCAT technique. In addition, a trend toward significance for achieving lower maximum dose value to the optic nerves and/or pathway was observed with VMAT (11=0.073). DCAT provided significantly lower MU values (3097.14 vs. 1479.09; p=0.00006). CONCLUSION VMAT was able to provide better target conformity and lower risk of brain radionecrosis at least dosimetrically in multifraction SRS for patients with multiple brain metastases. DCAT may he chosen in patients with relatively poor performance status or low tolerance to long-lasting radiotherapy sessions.Öğe GAS5 oligonucleotides as therapeutic agents in breast cancer(Ame Publ Co, 2016) Fayda, Merdan; Gezer, UğurAlthough relatively less is known about the long non-coding RNA (lncRNA) than the essential protein coding genes, several of them have organismal functions such as lethal knockouts, apoptosis etc. (1,2). Growth arrest specific genes 5 (GAS5) has proven to be pro-apoptotic in breast cancer (BC) cell lines (3). In their paper entitled “The hormone response element mimic sequence of GAS5 lncRNA is sufficient to induce apoptosis in breast cancer cells” published in March issue of Oncotarget by Pickard and Williams (4) report that an oligonucleotide representing the hormone response element mimic (HREM) sequence within GAS5 alone is able to promote the apoptosis of BC cells similar to fulllength GAS5.Öğe Having ypN0 may not be enough to abandon the Postmastectomy Radiotherapy (PMRT) in Her-2 positive patients(Elsevier Ireland Ltd, 2023) Fayda, Merdan[Abstract Not Available]
