Araştırma Çıktıları

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Author: search.filters.author.Goksel, Evren Ozan

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    A Dosimetric Plan Study to Increase the Dose from 63 Gy to 70 Gy in Early-Stage Glottic Larynx Cancer
    (KARE PUBL, 2020-01-01) Okutan, Murat; Sengul, Burak; Koksal, Canan; Goksel, Evren Ozan; Toraman, Kubra Ozkaya; Demir, Bayram; Altun, Musa
    OBJECTIVE The present study aims to compare the treatment plan parameters of different radiotherapy techniques {[}3D-Conformal Radiotherapy (3D-CRT), Dynamic - Intensity Modulated Radiotherapy (D-IMRT), Intensity Modulated Arc Therapy (IMAT) and Helical Tomotherapy (HT)] in Early-Stage Glottic Larynx (EGL) cancer to increase the treatment dose from 63 Gy to 70 Gy. METHODS The dose prescription was defined as 2.12 Gy per fraction to a total of 33 fractions. 95\% of Planning Treatment Volume-63 Gy (PTV-63) and Planning Treatment Volume-70 (PTV- 70) treatment volumes received the treatment dose of at least 63 and 70 Gy, respectively. The conventional-boost technique was used for 3D-CRT and the simultaneous integrated boost technique was used for other techniques. RESULTS The doses obtained from carotid arteries, thyroid and submandibular glands using IMRT, IMAT, and FIT were significantly lower than 3D-CRT. The study results pointed out the possibility of giving a treatment dose of 70 Gy to the PTV of EGI. with all planning techniques, with some advantages and disadvantages between them. All IMRT techniques provided superiority to 3D-CRT on the doses of the carotid artery, the thyroid gland, the submandibular glands, and the pharyngeal constrictor muscles with less variation between them. CONCLUSION The IMAT and 3D-CRT techniques yielded lower monitor unit values compared to other techniques. Normal tissue radiation exposure was lowest with the 3D-CRT technique. We recommend to increase the treatment dose from 63 Gy to 70 Gy in the radiotherapy of EGL cancer but to select the technique according to the patient's condition.
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    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, Meric
    Objective: 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.
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    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, Meric
    Background 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 < 0.001