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Author: search.filters.author.Oymak, EzgiHas files: Yes

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    Comparison of Helical and TomoDirect Techniques with Simultaneous Integrated Boost in Early Breast Cancer Patients
    (REPORTS OF PRACTICAL ONCOLOGY AND RADIOTHERAPY, 2023) Onal, Cem; Bozca, Recep; Oymak, Ezgi; Guler, Ozan Cem
    Background: The aim of the study was to perform dosimetric comparisons of helical (H) and TomoDirect (TD) plans for whole-breast irradiation (WBI) with simultaneous integrated boost (SIB) in early-stage breast cancer patients undergoing breast conserving surgery.Materials and methods: Fifty patients, 25 with left-side and 25 with right-side tumors, were determined for a treatment planning system for a total dose of 50.4Gy in 1.8Gy per fraction to WBI, with a SIB of 2.3Gy per fraction delivered to the tumor bed. The planning target volume (PTV) doses and the conformity (CI) and homogeneity indices (HI) for PTV(breast )and PTVboost, as well as organ-at-risk (OAR) doses and treatment times, were compared between the H and TD plans.Results: All plans met the PTV coverage criteria for the H plan, except for mean V107 of PTVbreast for TD plan. The H plan yielded better homogeneity and conformity of dose distribution compared to the TD plan. The ipsilateral mean lung doses were not significantly different between the two plans. The TD plans is advantageous for mean doses to the heart, contralateral breast and lung, spinal cord, and esophagus than the H plans. In both the H and TD plans, the right-sided breast patients had lower heart dose parameters than the left-sided breast patients. The TD plan is superior to the H plan in sparing the contralateral breast and lung by decreasing low-dose volumes.Conclusions: While the OAR dose advantages of TD are appealing, shorter treatment times or improved dose homogeneity and conformity for target volume may be advantageous for H plan.
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    Dosimetric Comparison of Volumetric Arc Therapy Methods for Stereotactic Body Radiotherapy in Liver Metastasis
    (2022) Oymak, Ezgi; Gueler, Ozan Cem; Oenal, Cem
    OBJECTIVE Volumetric arc therapy (VMAT) is advantageous for stereotactic body radiotherapy (SBRT) delivery; however, it is still unknown which rotational method is optimal for the treatment of liver metastases. This study aims to compare the dosimetric data of SBRT plans with VMAT techniques and helical tomotherapy (HT) in 18 liver metastasis patients. METHODS Three plans were generated: VMAT(M) was generated with Monaco Treatment Planning System (TPS), VMAT(E) with an Eclipse TPS, and HT plans were generated using a Hi-Art Tomotherapy system. The prescribed dose was 54 Gy delivered in three fractions. The planning target volume (PTV) doses and organs at risk (OAR) doses were compared between three plans. RESULTS All plans met the criteria for PTV coverage. Maximum PTV doses were significantly higher in VMAT(M) plan, and minimum PTV doses were significantly lower in VMAT(E )plan. The dose conformity and ho-mogeneity indices of PTV were better in VMAT(E) plan. Only mean bowel maximum dose was significantly higher in HT plan compared to VMAT(M) plan only. The liver D-mean were significantly higher in PTV larger than 50 cm3. Liver D-mean in PTV > 50 cm(3) was significantly less in VMAT(M )plan compared to HT (p=0.04) and VMAT(E) plans (p=0.04). CONCLUSION All three plans met the criteria for PTV coverage with no significant difference in OARs doses. VMAT(E) plan yielded better homogeneity and conformity in PTV compared to VMAT(M) and HT, and healthy liver tissue was better spared especially in larger tumors (> 50 cm(3)) with VMAT(E) plans.