Fakülteler / Faculties

Permanent URI for this communityhttps://hdl.handle.net/11727/1395

Browse

Filters

2017 - 20203

Settings

Author: search.filters.author.Dolek, YemlihaSubject: search.filters.subject.Prostate cancer

Search Results

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Is It Essential to Use Fiducial Markers During Cone-Beam CT-Based Radiotherapy for Prostate Cancer Patients?
    (2017) Yildirim, Berna A.; Onal, Cem; Dolek, Yemliha; 0000-0001-6661-4185; 0000-0002-2742-9021; 27730453; V-5717-2017; D-5195-2014; HOC-5611-2023
    To compare soft-tissue cone-beam computed tomography (CBCT-P) and fiducial marker (CBCT-FM)-based image guided radiotherapy in prostate cancer patients. Sixteen prostate cancer patients were treated with volumetric modulated arc therapy. Manual alignment using CBCT-P and CBCT-FM was performed for each patient. Couch shifts were calculated and compared between methods in the left-right (x), superior-inferior (y), and anterior-posterior (z) directions. CBCT-P and CBCT-FM alignments were compared using 252 scans from the 16 patients. Mean displacement from zero was 2.4 +/- 1.3, 1.7 +/- 1.2, and 1.8 +/- 1.1 mm for CBCT-P and 2.3 +/- 1.3, 1.7 +/- 1.1 and 1.8 +/- 1.1 mm for CBCT-FM in the x, y and z directions, respectively. There was no difference in median displacement between CBCT-P and CBCT-FM; however, there was a significant positive correlation between CBCT-P- and CBCT-FM-based displacements in the x (r = 0.881; p < 0.001), y (r = 0.789; p < 0.001) and z (r = 0.856; p < 0.001) directions by linear regression analysis. Systematic deviations within each group were < 1 mm; however, random and systematic errors were similar in the x and y directions but larger in the z direction. Our study demonstrated that CBCT-FM was not superior to CBCT-P for image-guided radiotherapy in prostate cancer patients.
  • No Thumbnail Available
    Item
    Incidental testicular doses during volumetric-modulated arc radiotherapy in prostate cancer patients
    (2020) Onal, Cem; Bozca, Recep; Dolek, Yemliha; Guler, Ozan Cem; Arslan, Gungor; 0000-0001-6908-3412; 0000-0002-2742-9021; 32125635; AAC-5654-2020; D-5195-2014
    Purpose To compare the incidental testicular doses during volumetric-modulated arc therapy (VMAT) in patients receiving prostate-only and pelvic lymphatic irradiation. Materials and methods Testicular doses in 40 intermediate- and high-risk prostate cancer patients were determined on treatment planning system (TPS) using the VMAT technique at 6 MV. Scattered testicular doses were also measured by MOSFET detectors placed on testis surface. The testicular doses of patients treated with prostate-only and pelvic field irradiation were compared. Results The median testicular doses measured per 200 cGy fraction by TPS and MOSFET detectors were 1.7 cGy (0.7-4.1 cGy) and 4.8 cGy (3.6-8.8 cGy), respectively. The TPS doses and MOSFET readings showed a significant strong correlation (Pearson r = 0.848, p < 0.001). The testicular doses measured by TPS (1.34 +/- 0.36 cGy vs. 2.60 +/- 0.95 cGy; p < 0.001) and MOSFET (4.52 +/- 0.64 cGy vs. 6.56 +/- 1.23 cGy; p < 0.001) were significantly lower in patients with prostate-only irradiation than in those with pelvic field irradiation. The mean cumulative scattered dose for prostate-only field delivering 78 Gy was 1.8 Gy and that for pelvic field irradiation was 2.6 Gy, consistent with the reported findings. Conclusions The patients with prostate-only irradiation received lower testicular doses than those with additional pelvic field irradiation possibly due to the increased scattered doses in large field irradiation using the VMAT technique. The clinical response to increased incidental testicular doses due to pelvic field irradiation remains unknown, and it warrants further investigation.
  • No Thumbnail Available
    Item
    Role of 68-Ga-PSMA-PET/CT in pelvic radiotherapy field definitions for lymph node coverage in prostate cancer patients
    (2020) Onal, Cem; Ozyigit, Gokhan; Guler, Ozan Cem; Hurmuz, Pervin; Torun, Nese; Tuncel, Murat; Dolek, Yemliha; Yedekci, Yagiz; Oymak, Ezgi; Tilki, Burak; Akyol, Fadil; 0000-0002-2742-9021; 0000-0001-6908-3412; 32861704; AAE-2718-2021; D-5195-2014; AAC-5654-2020
    Purpose: To evaluate the distribution of metastatic lymph nodes (LN) detected on Ga-68-PSMA-positron emission tomography/computed tomography (PET/CT) in treatment-naive prostate cancer (PC) patients and to analyze the LN coverage rates of the pelvic fields defined in the GETUG trial and RTOG guidelines and a pelvic field extending superiorly from the L4/L5 interspace. Materials and methods: Ga-68-PSMA-PET/CT images obtained at diagnosis of 138 PC patients were retro-spectively analyzed. The number and locations of Ga-68-PSMA-positive LNs were co-registered with one single-planning CT. The numbers, locations, and sizes of LNs located outside the three pelvic volumes were investigated for the entire cohort and for patients with LN metastasis in the pelvic area only. Results: A total of 441 PSMA-PET-positive LN metastases were identified. The most frequent metastatic LNs were internal iliac LNs (25.2%). Para-aortic and presacral LNs outside the three pelvic fields were present in 20 (14.5%) and 22 patients (15.9%), respectively. The LN coverage rates according to the GETUG trial, the RTOG guidelines, and the pelvic field extending superiorly from L4/L5 were 44.2%, 52.2%, and 71, respectively, in the entire cohort and 51.7%, 61 and 83.1%, respectively, in patients with only pelvic LN metastasis. The number of metastatic LNs was a predictive factor for LNs located outside the three pelvic fields. Conclusions: Extending the cranial margin of the pelvic field from L5/S1 to L4/L5 increases the accuracy of pelvic field irradiation in approximately 20% of patients, highlighting the importance of proximal common iliac irradiation, particularly in patients with multiple LN metastasis. (C) 2020 Elsevier B.V. All rights reserved.