Tıp Fakültesi / Faculty of Medicine

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Author: search.filters.author.Onal, CemSubject: search.filters.subject.Dosimetry

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    Dosimetric Analysis of Testicular Doses in Prostate Intensity-Modulated and Volumetric-Modulated Arc Radiation Therapy at Different Energy Levels
    (2016) Onal, Cem; ArsIan, Gungor; Dolek, Yemliha; Efe, Esma; 0000-0002-2742-9021; 27623736; D-5195-2014
    The aim of this study is to evaluate the incidental testicular doses during prostate radiation therapy with intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc radiotherapy (VMAT) at different energies. Dosimetric data of 15 patients with intermediate-risk prostate cancer who were treated with radiotherapy were analyzed. The prescribed dose was 78 Gy in 39 fractions. Dosimetric analysis compared testicular doses generated by 7-field intensity-modulated radiotherapy and volumetric modulated arc radiotherapy with a single arc at 6, 10, and 15 MV energy levels. Testicular doses calculated from the treatment planning system and doses measured from the detectors were analyzed. Mean testicular doses from the intensity-modulated radiotherapy and volumetric-modulated arc radiotherapy per fraction calculated in the treatment planning system were 16.3 +/- 10.3 cGy vs 21.5 +/- 11.2 cGy (p = 0.03) at 6 MV, 13.4 +/- 10.4 cGy vs 17.8 +/- 10.7 cGy (p = 0.04) at 10 MV, and 10.6 +/- 8.5 cGy vs 14.5 +/- 8.6 cGy (p = 0.03) at 15 MV, respectively. Mean scattered testicular doses in the phantom measurements were 99.5 +/- 17.2 cGy, 118.7 +/- 16.4 cGy, and 193.9 +/- 14.5 cGy at 6, 10, and 15 MV, respectively, in the intensity-modulated radiotherapy plans. In the volumetric-modulated arc radiotherapy plans, corresponding testicular doses per course were 90.4 +/- 16.3 cGy, 103.6 +/- 16.4 cGy, and 139.3 +/- 14.6 cGy at 6, 10, and 15 MV, respectively. In conclusions, this study was the first to measure the incidental testicular doses by intensity-modulated radiotherapy and volumetric-modulated arc radiotherapy plans at different energy levels during prostate-only irradiation. Higher photon energy and volumetric-modulated arc radiotherapy plans resulted in higher incidental testicular doses compared with lower photon energy and intensity-modulated radiotherapy plans. (C) 2016 American Association of Medical Dosimetrists.
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    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.