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Item V30 as a predictor for radiation-induced hypothyroidism: a dosimetric analysis in patients who received radiotherapy to the neck(BIOMED CENTRAL LTD, 2014-01-01) Akgun, Zuleyha; Atasoy, Beste M.; Ozen, Zeynep; Yavuz, Dilek; Gulluoglu, Bahadir; Sengoz, Meric; Abacioglu, UfukIntroduction: The purpose of this study is to evaluate the possible predictors of thyroid disorders after neck radiotherapy, with a focus on radiation dose-volume factors. Methods: Thyroid function was measured in 100 patients who had received radiotherapy to the neck, including the thyroid. All radiation-induced thyroid dysfunctions were determined with an endpoint of abnormal thyroid stimulating hormone (TSH), free triiodothyronine (fT3) and thyroxine (fT4) and thyroid peroxidase antibodies and (TPA). The total volume of the thyroid, mean radiation dose to the thyroid (Dmean) and thyroid volume percentage that received radiation doses of 10-50 Gy (V10-V50) were calculated in all patients. The evaluated risk factors for thyroid dysfunction included dose-volume parameters, sex, age, previous surgery, chemotherapy and comorbidity. Results: There were 52 patients with hypothyroidism and V30 (p = 0.03), thyroid volume (p = 0.01) and Dmean (p = 0.03) appeared to be correlated with hypothyroidism in univariate analysis. However, there was not association found in multivariate analysis for these factors. Conclusions: Thyroid disorders after radiation therapy to the neck still represent a clinically underestimated problem. V30 may be a useful tool for evaluating the risk of hypothyroidism when determining an individual patient's treatment.Item Gamma Knife Radiosurgery for Hemorrhagic Brainstem Cavernomas(TURKISH NEUROSURGICAL SOC, 2019-01-01) Ucuncu Kefeli, Aysegul; Sengoz, Meric; Peker, SelcukAIM: To assess treatment results of gamma knife radiosurgery (GKRS) for hemorrhagic brainstem cavernous malformations (BSCMs). MATERIAL and METHODS: A retrospective review of patients with hemorrhagic BSCMs, who were treated at the Acibadem Kozyatagi Hospital GKRS unit from May 2007 to October 2015 was performed. RESULTS: In total, 82 patients were identified. All patients had experienced at least one hemorrhagic event (range 1-3), and all of them presented with radiological evidence of hemorrhage. The median target volume was 0.3 ml, and the median marginal radiation dose was 12 Gy. The mean durations before and after surgery were 25.5 (range 1-204) months, and 50.3 (range 13-113) months, respectively. Pre-treatment hemorrhage rates were calculated from the date of first hemorrhage to the date of radiosurgery. There were 97 bleeds over 174.4 patient-years during the observation period, with an annual hemorrhage rate of 55.7\%. If the first bleed is excluded, the annual hemorrhage rate was 8.6\%. Only three patients demonstrated re-bleeding, which occurred at 3, 12 and 79 months after radiosurgery. Over a total follow up time of 344 patient-years the annual re-bleeding rate was therefore 0.87\%, indicating that the risk of BSCM hemorrhage was significantly decreased by radiosurgery. CONCLUSION: GKRS was a safe and effective treatment for symptomatic low volume BSCMs when a low marginal dose is used. A randomized controlled trial is needed that compares GKRS to observation if we want to establish the true efficacy of this treatment.Item Gamma Knife Radiosurgery for Arteriovenous Malformations: Clinical Series of 199 Patients(TURKISH NEUROSURGICAL SOC, 2017-01-01) Arslan, Ipek; Tezcanli, Evrim; Yilmaz, Meltem; Cizmeli, Olcay; Sengoz, Meric; Peker, SelcukAIM: Cerebral arteriovenous malformations (AVM) are pathological connections between arteries and veins without capillaries. Stereotactic radiosurgery (RS) is a proven and accepted treatment method for cerebral AVMs. Our objective was to analyze the factors influencing the clinical outcome in patients suffering from AVMs. MATERIAL and METHODS: We retrospectively reviewed 199 patients who were treated with Gamma-Knife RS for intracranial AVMs between 13 October 2005 and 31 October 2010. There were 89 male, 110 female patients with a median age of 32 years (range, 3-74 years). Obliteration was assessed with MRI angiography and DSA imaging. RESULTS: Complete obliteration rate after RS was 71 \% (141 out of 199), including second RS treatments. In terms of obliteration rates, there was no significant difference between patients younger and older than 21 years old (p=0.669). After RS, 3 patients died due to intracranial hemorrhage and 1 died of heart disease. Death from AVM was determined as 1.5 \%. Intracranial hemorrhage was observed in 7 (3.5 \%) patients post-RS. CONCLUSION: Obliteration was found to be associated with Spetzler-Martin Grade, Pollock-Flickinger Grade, AVM volume, RS dose, bleeding history before RS and no previous embolization before RS. Gamma knife RS is an effective treatment method for the treatment of AVMs both for pediatric and adult patients. It provides high obliteration and low mortality rates.Item Gamma Knife Radiosurgery for Tumors of the Endolymphatic Sac(TURKISH NEUROSURGICAL SOC, 2017-01-01) Ucuncu Kefeli, Aysegul; Yilmaz, Meltem; Sengoz, Meric; Peker, SelcukTumors of the endolymphatic sac are locally invasive temporal bone neoplasms. Radical surgical excision is the treatment of choiceItem Magnetic resonance image-guided adaptive stereotactic body radiotherapy for prostate cancer: preliminary results of outcome and toxicity(BRITISH INST RADIOLOGY, 2021-01-01) Ugurluer, Gamze; Atalar, Banu; Mustafayev, Teuta Zoto; Gungor, Gorkem; Aydin, Gokhan; Sengoz, Meric; Abacioglu, Ufuk; Tuna, Mustafa Bilal; Kural, Ali Riza; Ozyar, EnisObjective: Using moderate or ultra-hypofractionation, which is also known as stereotactic body radiotherapy (SBRT) for treatment of localized prostate cancer patients has been increased. We present our preliminary results on the clinical utilization of MRI-guided adaptive radiotherapy (MRgRT) for prostate cancer patients with the workflow, dosimetric parameters, toxicities and prostate-specific antigen (PSA) response. Methods: 50 prostate cancer patients treated with ultrahypofractionation were included in the study. Treatment was performed with intensity-modulated radiation therapy (step and shoot) technique and daily plan adaptation using MRgRT. The SBRT consisted of 36.25 Gy in 5 fractions with a 7.25 Gy fraction size. The time for workflow steps was documented. Patients were followed for the acute and late toxicities and PSA response. Results: The median follow-up for our cohort was 10 months (range between 3 and 29 months). The median age was 73.5 years (range between 50 and 84 years). MRgRT was well tolerated by all patients. Acute genitourinary (GU) toxicity rate of Grade 1 and Grade 2 was 28 and 36\%, respectively. Only 6\% of patients had acute Grade 1 gastrointestinal (GI) toxicity and there was no Grade 2G1 toxicity. To date, late Grade 1 GU toxicity was experienced by 24\% of patients, 2\% of patients experienced Grade 2 GU toxicity and 6\% of patients reported Grade 2 GI toxicity. Due to the short follow-up, PSA nadir has not been reached yet in our cohort. Conclusion: In conclusion, MRgRT represents a new method for delivering SBRT with markerless soft tissue visualization, online adaptive planning and real-time tracking. Our study suggests that ultra-hypofractionation has an acceptable acute and very low late toxicity profile. Advances in knowledge: MRgRT represents a new markerless method for delivering SBRT for localized prostate cancer providing online adaptive planning and real-time tracking and acute and late toxicity profile is acceptable.Item Dealing with the gray zones in the management of gastric cancer: The consensus statement of the Istanbul Group(AVES, 2019-01-01) Aytac, Erman; Aslan, Fatih; Cicek, Bahattin; Erdamar, Sibel; Gurses, Bengi; Guven, Koray; Falay, Okan; Karahasanoglu, Tayfun; Selcukbiricik, Fatih; Selek, Ugur; Atalar, Banu; Balik, Emre; Tozun, Nurdan; Rozanes, Izzet; Arican, Ali; Hamzaoglu, Ismail; Baca, Bilgi; Mandell, Nil Molinas; Saruc, Murat; Goksel, Suha; Demir, Gokhan; Agaoglu, Fulya; Yakicier, Cengiz; Ozbek, Ugur; Ozben, Volkan; Ozyar, Enis; Guner, Ahmet Levent; Er, Ozlem; Kaban, Kerim; Bolukbasi, Yasemin; Bugra, Dursun; Ahishali, Emel; Asian, Fatih; Boz-bas, Aysun; Hamzaoglu, Hulya; Karaman, Ahmet; Kucukmetin, Nurten Turkel; Vardareli, Eser Kutsal; Onder, Fatih Oguz; Sisman, Gurhan; Tiftikci, Arzu; Unal, Hakan Umit; Yapali, Suna; Acar, Sami; Agcaoglu, Orhan; Aghayeva, Afag; Akyuz, Ali; Atasoy, Deniz; Batik, Emre; Bayraktar, Ilknur Erenler; Bayram, Onur; Bilgic, Cagri; Bilgin, Ismail Ahmet; Can, Ugur; Dulgeroglu, Onur; Durukan, Ugur; Gencosmanoglu, Rasim; Gonenc, Murat; Gurbuz, Bulent; Kaya, Mesut; Omarov, Nail; Ozben, Volkan; Ozgur, Ilker; Ozoran, Emre; Sobutay, Erman; Uras, Cihan; Uymaz, Derya; Zenger, Serkan; Ozbek, Ugur; Yakicier, M. Cengiz; Afsar, Cigdem Usul; Bozkurt, Mustafa; Demir, Atakan; Er, Ozlem; Kanitez, Metin; Korkmaz, Taner; Mandel, Nil Molina; Mert, Askhan Guven; Ozer, Leyla; Sonmez, Ozlem; Tunali, Didem; Uluc, Basak Oyan; Yazar, Aziz; Yildiz, Ibrahim; Demirkurek, Cengiz; Guner, Ahmet Levent; Vardareli, Erkan; Armutlu, Aye; Baba, Fisun; Ersozlu, Ilker; Kapran, Yersu; Sahin, Davut; Abacioglu, Mehmet Ufuk; Bese, Nuran; Durankus, Nilufer Kilic; Gural, Zeynep; Ozyar, Enis; Sengoz, Meric; Sezen, Duygu; Caliskan, Can; Guven, Koray; Karaaslan, Ercan; Kizilkaya, Esref; Suleyman, Erdogan; Grp, IstanbulThe geographical location and differences in tumor biology significantly change the management of gastric cancer. The prevalence of gastric cancer ranks fifth and sixth among men and women, respectively, in Turkey. The international guidelines from the Eastern and Western countries fail to manage a considerable amount of inconclusive issues in the management of gastric cancer. The uncertainties lead to significant heterogeneities in clinical practice, lack of homogeneous data collection, and subsequently, diverse outcomes. The physicians who are professionally involved in the management of gastric cancer at two institutions in Istanbul, Turkey, organized a consensus meeting to address current problems and plan feasible, logical, measurable, and collective solutions in their clinical practice for this challenging disease. The evidence-based data and current guidelines were reviewed. The gray zones in the management of gastric cancer were determined in the first session of this consensus meeting. The second session was constructed to discuss, vote, and ratify the ultimate decisions. The identification of the T stage, the esophagogastric area, imaging algorithm for proper staging and follow-up, timing and patient selection for neoadjuvant treatment, and management of advanced and metastatic disease have been accepted as the major issues in the management of gastric cancer. The recommendations are presented with the percentage of supporting votes in the results section with related data.Item Gamma Knife Radiosurgery for Anterior Clinoid Process Meningiomas: A Series of 61 Consecutive Patients(ELSEVIER SCIENCE INC, 2020-01-01) Akyoldas, Goktug; Hergunsel, Omer Batu; Yilmaz, Meltem; Sengoz, Meric; Peker, SelcukOBJECTIVE: Gamma Knife radiosurgery (GKRS) outcomes for anterior clinoid process (ACP) meningiomas have not been specifically reported within any meningioma series. We present the initial and largest series in the literature that describes the presenting features, radiosurgery parameters, and radiologic and long-term clinical outcomes for 61 patients with ACP meningiomas treated with GKRS. METHODS: Medical records were reviewed for 61 consecutive patients at a single center who underwent GKRS for ACP meningioma between 2008 and 2016. RESULTS: Of 61 patients with ACP meningiomas, 49 (80\%) were treated with GKRS as primary treatment, and 12 (20\%) were treated with GKRS as an adjuvant therapy. Before GKRS, 29 patients presented with visual impairment and 50 patients presented with headache. Median patient age was 54.9 years. Median tumor volume was 3.2 cm(3), and median margin dose was 12.0 Gy. The median radiologic follow-up time after GKRS was 75 months. During follow-up, tumor volume regressed in 37 cases (61\%) and remained unchanged in 24 cases (39\%). None of the patients experienced tumor volume progression. Tumor volume <3 cm(3) was an independent predictor of tumor volume regression after GKRS (univariate analysis, P = 0.047Item Limited field adaptive radiotherapy for glioblastoma: changes in target volume and organ at risk doses(KOREAN SOC THERAPEUTIC RADIOLOGY \& ONCOLOGY, 2022-01-01) Senkesen, Oznur; Tezcanli, Evrim; Abacioglu, Mehmet Ufuk; Ozen, Zeynep; Cone, Derya; Kucucuk, Halil; Goksel, Evren Ozan; Arifoglu, Alptekin; Sengoz, MericObjective: This study aimed to investigate the tumor volume changes occurring during limited-field radiotherapy (RT) for glioblastoma patients and whether a volume-adapted boost planning approach provided any benefit on tumor coverage and normal tissue sparing. Materials and Methods: Twenty-four patients underwent simulation with magnetic resonance (MR) and computed tomography (CT) scans prior to RT (MR\_initial, CT\_initial) and boost treatment (MR\_adapt, CT\_adapt). For the boost phase, MR\_initial and MR\_adapt images were used to delineate GTV(2) and GTV(2\_adapt), respectively. An initial boost plan (Plan\_initial) created on CT\_initial for PTV2 was then reoptimized on CT\_adapt by keeping the same optimization and normalization values. Plan\_adapt was generated on CT\_adapt for PTV(2\_adapt )volume. Dose volume histogram parameters for target volumes and organs-at-risk were compared using these boost plans generated on CT\_adapt. Plan\_initial and Plan\_adaptive boost plans were summed with the first phase plan and the effect on the total dose was investigated. Results: Target volume expansion was noted in 21 0 /c, of patients while 791b had shrinkage. The average difference for the initial and adaptive gross tumor volume (G1V), clinical target volume (CTV), and planning target volume (PTV) volumes were statistically significant. Maximum dose differences for brainstem and optic chiasm were significant. Healthy brain tissue V-10 and ipsilateral optic nerve maximum doses were found to decrease significantly in Plan\_adaptive. Conclusion: Results of this study confirm occurrence of target volume changes during RT for glioblastoma patients. An adaptive plan can provide better normal tissue sparing for patients with lesion shrinkage and avoid undercoverage of treatment volumes in case of target volume expansion especially when limited-fields are used.Item Dosimetric evaluation of VMAT and helical tomotherapy techniques comparing conventional volumes with clinical target volumes based on new ESTRO ACROP post-mastectomy with immediate implant reconstruction contouring guidelines(BMC, 2022-01-01) Goksel, Evren Ozan; Tezcanli, Evrim; Arifoglu, Alptekin; Kucucuk, Halil; Senkesen, Oznur; Abacioglu, Ufuk; Aslay, Isik; Sengoz, MericBackground The ESTRO-ACROP Consensus Guideline (EACG) recommends implant excluded clinical target volume (CTVp) definitions for post-mastectomy radiation therapy after implant-based immediate breast reconstruction (IBR). The purpose of this study is to investigate the effectiveness of Helical Tomotherapy (HTp) and Volumetric Modulated Arc Therapy (VMATp) treatment techniques in terms of CTVp coverage and reduced organ at risk (OAR), normal tissue and implant doses when CTVp was used for treatment planning as the target structure instead of conventional CTV. Methods Eight left-sided and eight right-sided breast cancer patients who underwent IBR after mastectomy were included in this study. Planning CT data sets were acquired during free breathing and patients were treated with HT technique targeted to conventional CTV. Retrospectively, CTVp was delineated based on EACG by the same radiation oncologist, and treatment plans with HTp and VMATp techniques were generated based on CTVp. For each patient, relevant dosimetric parameters were obtained from three different treatment plans. Results There was no statistically significant difference on target coverage in terms of, PTVp-D95, PTVp-Vpres, homogeneity index (p > 0.05) between HTp and VMATp plans. But, the conformity numbers were significantly higher (HTp vs VMATp, 0.69 +/- 0.15 vs 0.79 +/- 0.12) for VMATp (Z = - 2.17, p = 0.030). While HTp significantly lowered Dmax and Dmean for LAD (LAD-D-max: chi(2) = 12.25, p = 0.002 and LAD-D-mean: chi(2) = 12.30, p = 0.002), neither HTp nor VMATp could reduce maximum and mean dose to heart (p > 0.05). Furthermore, heart volume receiving 5 Gy was significantly higher for VMATp when compared to HTp (21.2 +/- 9.8 vs 42.7 +/- 24.8, p: 0.004). Both techniques succeeded in reducing the mean dose to implant (HTp vs HT, p < 0.001Item GAMMA KNIFE RADIOSURGERY FOR RECURRENT HIGH GRADE GLIOMAS(OXFORD UNIV PRESS INC, 2014-01-01) Peker, Selcuk; Kabalay, Ipek Arslan; Tezcanli, Evrim; Yilmaz, Meltem; Sengoz, Meric