Tıp Fakültesi / Faculty of Medicine

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2014 - 20193

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Author: search.filters.author.Dolek, YemlihaSubject: search.filters.subject.Brachytherapy

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    Uterine Perforation During 3-Dimensional Image-Guided Brachytherapy in Patients With Cervical Cancer Baskent University Experience
    (2014) Onal, Cem; Guler, Ozan Cem; Dolek, Yemliha; Erbay, Gurcan; https://orcid.org/0000-0002-2742-9021; https://orcid.org/0000-0001-6908-3412; https://orcid.org/0000-0002-1706-8680; 24407583; HOC-5611-2023; AAC-5654-2020; AAK-5370-2021
    Objectives This study aimed to determine the incidence and characteristics of uterine perforation at our department using 3-dimensional computed tomography (CT)-based brachytherapy (BRT). The characteristics of the patients presenting with perforation and impact of the perforation on the treatment course were also analyzed. Materials and Methods The clinical and radiologic data of 200 patients with biopsy-proven cervical cancer treated using CT-based BRT were retrospectively evaluated. All patients had undergone tandem-based intracavitary BRT, and 67 patients had undergone magnetic resonance imaging (MRI) before BRT. Results Of the 200 patients, 17 (8.5%) had uterine perforation. Of the 626 applications with CT images, 30 (4.8%) resulted in uterine perforation. The median age of patients with perforation was higher (68 years; range, 44-89 years) than that of the patients without perforation (59 years; range, 21-87 years), and the mean (SD) tumor size at diagnosis was larger in patients with perforation (7.0 [1.5] cm) than in patients without perforation (5.0 [1.5] cm). The most frequent perforation site was the posterior uterine wall (8 patients), followed by the fundus (5 patients) and anterior wall (4 patients). Of the 7 patients with a retroverted uterus, 4 had uterine perforation during BRT. In 67 patients with MRI delivered before BRT, only 3 (4%) had uterine perforation, and 2 of the 3 patients with uterine perforation had a retroverted uterus. However, of the 133 patients with no MRI evaluation before BRT, 14 (11%) had uterine perforation. No life-threatening complications or signs of intraperitoneal tumor cell seeding were observed. Conclusions Older age, larger tumors, a retroverted uterus, and a stenotic cervical os were all predisposing factors for uterine perforation during BRT. Preoperative MRI is a feasible and safe method to decrease the risks of uterine perforation and could be used preoperatively in centers where intraoperative ultrasonography is not used in routine practice.
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    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.
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    Effects of vaginal cylinder position on dose distribution in patients with endometrial carcinoma in treatment of vaginal cuff brachytherapy
    (2017) Ozdemir, Yurday; Dolek, Yemliha; Onal, Cem; 0000-0002-2218-2074; 0000-0002-2742-9021; 28725246; AAG-5629-2021; D-5195-2014
    Purpose: To investigate the impact of different cylinder positions on dosimetry of critical structures in patients with endometrial carcinoma undergoing three-dimensional image-based vaginal cuff brachytherapy (VCB). Material and methods: We delivered VCB at a dose of 4 Gy to a depth of 5 mm in the vaginal cuff of 15 patients using three different cylinder positions (neutral [N], parallel [P], and angled [A]) according to the longitudinal axis of the patient. We analyzed the dose-volume distribution and volumetric variability of the rectum and bladder. We converted the total doses to equivalent doses in 2 Gy (EQD(2)) using a linear-quadratic model (a/b = 3 Gy). Results: The mean rectum volume for the N, P, and A positions was 68.2 +/- 22.7 cc, 79.3 +/- 33.7 cc, and 74.2 +/- 29.6 cc, respectively. The mean rectum volume for the P position was significantly larger than that for the N position (p = 0.03). Relative to the N position, the A position resulted in a lower total EQD(2) in the highest irradiated 2 cc (D-2cc; p = 0.001), 1 cc (D-1cc; p = 0.004), and 0.1 cc (D-0.1cc; p = 0.047) of the rectum. Similarly, the P position resulted in a lower EQD(2) in the D-2cc (p = 0.018) and D-1cc (p = 0.024) of the rectum relative to the N position. In the bladder, the P position resulted in a higher EQD(2) in the D-2cc, relative to the N position (p = 0.02). There was no dosimetric difference between the P and A positions in either the rectum or the bladder. Conclusions: Vaginal cuff brachytherapy in the P and A positions is significantly superior to that in the N position in terms of rectum dosimetry. The bladder dose in the N position is considerably lower than that in the other positions.