Araştırma Çıktıları
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Item Estimation of secondary cancer risk after radiotherapy in high-risk prostate cancer patients with pelvic irradiation(WILEY, 2020-01-01) Haciislamoglu, Emel; Gungor, Gorkem; Aydin, Gokhan; Canyilmaz, Emine; Guler, Ozan Cem; Zengin, Ahmet Yasar; Yenice, Kamil MehmetWe aimed to estimate the risk of secondary cancer after radiotherapy (RT) in high-risk prostate cancer (HRPC) patients with pelvic irradiation. Computed tomography data of five biopsy-proven HRPC patients were selected for this study. Two different planning target volumes (PTV(1)and PTV2) were contoured for each patient. The PTV(1)included the prostate, seminal vesicles, and pelvic lymphatics, while the PTV(2)included only the prostate and seminal vesicles. The prescribed dose was 54 Gy for the PTV(1)with a sequential boost (24 Gy for the PTV2). Intensity-modulated RT (IMRT) and volumetric modulated arc therapy (VMAT) techniques were used to generate treatment plans with 6 and 10 MV photon energies with the flattening filter (FF) or flattening filter-free (FFF) irradiation mode. The excess absolute risks (EARs) were calculated and compared for the bladder, rectum, pelvic bone, and soft tissue based on the linear-exponential, plateau, full mechanistic, and specific mechanistic sarcoma dose-response model. According to the models, all treatment plans resulted in similar risks of secondary bladder or rectal cancer and pelvic bone or soft tissue sarcoma except for the estimated risk of the bladder according to the full mechanistic model using IMRT((6MVItem Multi-Institutional Outcomes of Stereotactic Magnetic Resonance Image Guided Adaptive Radiation Therapy With a Median Biologically Effective Dose of 100 Gy(10) for Non-bone Oligometastases(ELSEVIER INC, 2022-01-01) Kutuk, Tugce; Herrera, Robert; Mustafayev, Teuta Z.; Gungor, Gorkem; Ugurluer, Gamze; Atalar, Banu; Kotecha, Rupesh; Hall, Matthew D.; Rubens, Muni; Mittauer, Kathryn E.; Contreras, Jessika A.; McCulloch, James; Kalman, Noah S.; Alvarez, Diane; Romaguera, Tino; Gutierrez, Alonso N.; Garcia, Jacklyn; Kaiser, Adeel; Mehta, Minesh P.; Ozyar, Enis; Chuong, Michael D.Purpose: Randomized data show a survival benefit of stereotactic ablative body radiation therapy in selected patients with oligometastases (OM). Stereotactic magnetic resonance guided adaptive radiation therapy (SMART) may facilitate the delivery of ablative dose for OM lesions, especially those adjacent to historically dose-limiting organs at risk, where conventional approaches preclude ablative dosing. Methods and Materials: The RS Search Registry was queried for OM patients (1-5 metastatic lesions) treated with SMART. Freedom from local progression (FFLP), freedom from distant progression (FFDP), progression-free survival (PFS), and overall survival (LS) were estimated using the Kaplan-Meier method. FFLP was evaluated using RECIST 1.1 criteria. Toxicity was evaluated using Common Terminology Criteria for Adverse Events version 4 criteria. Results: Ninety-six patients with 108 OM lesions were treated on a 0.35 T MR Linac at 2 institutions between 2018 and 2020. SMART was delivered to mostly abdominal or pelvic lymph nodes (48.1\%), lung (18.5\%), liver and intrahepatic bile ducts (16.7\%), and adrenal gland (11.1\%). The median prescribed radiation therapy dose was 48.5 Gy (range, 30-60 Gy) in 5 fractions (range, 3-15). The median biologically effective dose corrected using an alpha/beta value of 10 was 100 Gy10 (range, 48-180). No acute or late grade 3+ toxicities were observed with median 10 months (range, 3-25) follow-up. Estimated 1-year FFLP, FFDP, PFS, and OS were 92.3\%, 41.1\%, 39.3\%, and 89.6\%, respectively. Median FFDP and PFS were 8.9 months (95\% confidence interval, 5.2-12.6 months) and 7.6 months (95\% confidence interval, 4.5-10.6 months), respectively. Conclusions: To our knowledge, this represents the largest analysis of SMART using ablative dosing for non-bone OM. A median prescribed biologically effective dose of 100 Gy10 resulted in excellent early FFLP and no significant toxicity, likely facilitated by continuous intrafraction MR visualization, breath hold delivery, and online adaptive replanning. Additional prospective evaluation of dose-escalated SMART for OM is warranted. (C) 2022 The Author(s). Published by Elsevier Inc. on behalf of American Society for Radiation Oncology.Item Patient-Reported Tolerance of Magnetic Resonance-Guided Radiation Therapy(FRONTIERS MEDIA SA, 2020-01-01) Sayan, Mutlay; Serbez, Ilkay; Teymur, Bilgehan; Gur, Gokhan; Zoto Mustafayev, Teuta; Gungor, Gorkem; Atalar, Banu; Ozyar, EnisPurpose Magnetic resonance-guided radiation therapy (MRgRT) has been incorporated into a growing number of clinical practices world-wide, however, there is limited data on patient experiences with MRgRT. The purpose of this study was to prospectively evaluate patient tolerance of MRgRT using patient reported outcome questionnaires (PRO-Q). Methods Ninety patients were enrolled in this prospective observational study and treated with MRgRT (MRIdian Linac System, ViewRay Inc. Oakwood Village, OH, United States) between September 2018 and September 2019. Breath-hold-gated dose delivery with audiovisual feedback was completed as needed. Patients completed an in-house developed PRO-Q after the first and last fraction of MRgRT. Results The most commonly treated anatomic sites were the abdomen (47\%) and pelvis (33\%). Respiratory gating was utilized in 62\% of the patients. Patients rated their experience as positive or at least tolerable with mean scores of 1.0-2.8. The most common complaint was the temperature in the room (61\%) followed by paresthesias (57\%). The degree of anxiety reported by 45\% of the patients significantly decreased at the completion of treatment (mean score 1.54 vs. 1.36,p= 0.01). Forty-three percent of the patients reported some degree of disturbing noise which was improved considerably by use of music. All patients appreciated their active role during the treatment. Conclusion This evaluation of PROs indicates that MRgRT was well-tolerated by our patients. Patients' experience may further improve with adjustment of room temperature and noise reduction.Item Secondary cancer risk after whole-breast radiation therapy: field-in-field versus intensity modulated radiation therapy versus volumetric modulated arc therapy(BRITISH INST RADIOLOGY, 2019-01-01) Haciislamoglu, Emel; Cinar, Yunus; Gurcan, Fatih; Canyilmaz, Emine; Gungor, Gorkem; Yoney, AdnanObjective: In this study, we used the concept of organ-equivalent dose (OED) to evaluate the excess absolute risk (EAR) for secondary cancer in various organs after radiation treatment for breast cancer. Methods: Using CT data set of 12 patients, we generated three different whole-breast radiation treatment plans using 50 Gy in 2Gy fractions: three-dimensional conformal radiotherapy with a field-in-field (FinF) technique, intensity modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT). The OEDs were calculated from differential dose-volume histograms on the basis of the ``linear-exponential,{''} ``plateau,{''} and `'full mechanistic{''} dose-response models. Secondary cancer risks of the contralateral breast (CB), contralateral lung (CL), and ipsilateral lung (IL) were estimated and compared. Results: The lowest EARs for the CB, CL, and IL were achieved with FinF, which reduced the EARs by 77\%, 88\%. and 56\% relative to those with IMRT, and by 77\%, 84\%, and 58\% relative to those with VMAT, respectively. The secondary cancer risk for FinF was significantly lower than those of IMRT and VMAT. OED-based secondary cancer risks for CB and IL were similar when IMRT and VMAT were used, but the risk for CL was statistically lower when VMAT was used. Conclusion: The overall estimation of EAR indicated that the radiation-induced cancer risk of breast radiation therapy was lower with FinF than with IMRT and VMAT. Therefore, when secondary cancer risk is a major concern, FinF is considered to be the preferred treatment option in irradiation of whole-breast. Advances in knowledge: Secondary malignancy estimation after breast radiotherapy is becoming an important subject for comparative treatment planning.When secondary cancer risk a major concern, FinF technique is considered the preferred treatment option in whole breast patients.Item 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 Re-Irradiation of Non-Small Cell Lung Cell Cancer Recurrences with Stereotactic Body Radiotherapy(2016-01-01) Atalar, Banu; Sahin, Bilgehan; Gungor, Gorkem; Aydin, Gokhan; Yapici, Bulent; Ozyar, EnisItem Improvement of conformal arc plans by using deformable margin delineation method for stereotactic lung radiotherapy(WILEY, 2018-01-01) Gungor, Gorkem; Demir, Melek; Aydin, Gokhan; Yapici, Bulent; Atalar, Banu; Ozyar, EnisPurpose: Stereotactic body radiotherapy (SBRT) is an established treatment technique in the management of medically inoperable early stage non-small cell lung cancer (NSCLC). Different techniques such as volumetric modulated arc (VMAT) and three-dimensional conformal arc (DCA) can be used in SBRT. Previously, it has been shown that VMAT is superior to DCA technique in terms of plan evaluation parameters. However, DCA technique has several advantages such as ease of use and considerable shortening of the treatment time. DCA technique usually results in worse conformity which is not possible to ameliorate by inverse optimization. In this study, we aimed to analyze whether a simple method-deformable margin delineation (DMD)-improves the quality of the DCA technique, reaching similar results to VMAT in terms of plan evaluation parameters. Methods: Twenty stage I-II (T1-2, N0, M0) NSCLC patients were included in this retrospective dosimetric study. Noncoplanar VMAT and conventional DCA plans were generated using 6 MV and 10 MV with flattening filter free (FFF) photon energies. The DCA plan with 6FFF was calculated and 95\% of the PTV was covered by the prescription isodose line. Hot dose regions (receiving dose over 100\% of prescription dose) outside PTV and cold dose regions (receiving dose under 100\% of prescription dose) inside PTV were identified. A new PTV (PTV-DMD) was delineated by deforming PTV margin with respect to hot and cold spot regions obtained from conventional DCA plans. Dynamic multileaf collimators (MLC) were set to PTV-DMD beam eye view (BEV) positions and the new DCA plans (DCA-DMD) with 6FFF were generated. Three-dimensional (3D) dose calculations were computed for PTV-DMD volume. However, the prescription isodose was specified and normalized to cover 95\% volume of original PTV. Several conformity indices and lung doses were compared for different treatment techniques. Results: DCA-DMD method significantly achieved a superior conformity index (CI), conformity number (CIPaddick), gradient index (R-50\%), isodose at 2 cm (D-2 (cm)) and external index (CD) with respect to VMAT and conventional DCA plans (P < 0.05 for all comparisons). CI ranged between 1.00-1.07 (Mean: 1.02)