Publications by authors named "Hakan Epik"

2 Publications

  • Page 1 of 1

Dosimetric comparison of anterior posterior-posterior anterior 2-field three-dimensional conformal radiotherapy, 4-field three-dimensional conformal radiotherapy and "forward" plan intensity modulated radiotherapy techniques in female lymphoma patients irradiated to neck and mediastinum.

J Cancer Res Ther 2018 Oct-Dec;14(6):1389-1396

Department of Radiation Oncology, Dokuz Eylül University Medical Faculty, Izmir, Turkey.

Aim: Dosimetric comparison of three different techniques in female lymphoma patients who had radiotherapy (RT) to the neck and mediastinum.

Setting And Design: Retrospective clinical study.

Materials And Methods: Computerized tomography-simulator images of eight patients were obtained retrospectively. Using 6 MV-X photon energy, RT plans were formed with three different techniques (anterior posterior-posterior anterior 2-field three-dimensional conformal RT [AP-PA 2-field 3D-CRT], 4-field 3D-CRT and "forward" plan intensity modulated RT [FPIMRT]). Comparisons were in terms of homogeneity index (HI), conformity index (CI), and inhomogeneity coefficient for planning target volume (PTV); mean lung dose, V, V, V, V for lung; D, V, V, V for heart; D, V, V, V for breast; D for spine; D, V, V, V, V for thyroid.

Statistical Analysis Used: Since nonparametric tests had to be used due to the study population being < 30, Friedman and Wilcoxon signed-rank tests were implemented in trilateral and bilateral comparison of techniques, respectively. For statistical significance, P value was required to be <0.05.

Results: When FPIMRT was compared with AP-PA and 4-field techniques with respect to, HI (AP-PA/FPIMRT P: 0.017; 4-field/FPIMRT P: 0.03) and CI (AP-PA/FPIMRT P: 0.018; 4-field/FPIMRT P: 0.042), FPIMRT was more advantageous. In addition, FPIMRT was found more useful in terms of D (AP-PA/FPIMRT P: 0.012; 4-Field/FPIMRT P: 0.012) for spinal cord and D (AP-PA/FPIMRT P: 0.012; 4-field/FPIMRT P: 0.012) for thyroid.

Conclusion: FPIMRT was superior in terms of PTV homogeneity and conformity. However, it was observed that for normal tissues, FPIMRT was advantageous only for spinal cord and thyroid; but it was not the most advantageous technique for some of the dose-volume parameters of the breast, lung, and heart.
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February 2019

Experimental and Simulation Analysis of Radiation of the Beta Emitting Sources in a Magnetic Field.

Mol Imaging Radionucl Ther 2017 Jun;26(2):53-61

Dokuz Eylül University Faculty of Medicine, Department of Nuclear Medicine, İzmir, Turkey.

Objective: The behavior of beta particles under the magnetic field was investigated both theoretically and experimentally based on the assumption of reducing the damage to the normal tissues created by using magnetic field in radionuclide therapy.

Methods: A water-filled spherical medium and a beta particle source was formed by using Geant4 simulation software for the theoretical study. After applying a homogenous magnetic field, the volume of points at which the particles interact with the medium was calculated by determining particle range. The range of beta particles was examined using yttrium-90 source and Gafchromic films for the experimental study. The setup was kept in normal room conditions and in the magnetic resonance imaging device. Then the irradiated films were analyzed by creating isodose curves.

Results: With the increase of the magnetic field, the number of hits at the center was increased, but the number of hits at the outer boundaries decreased inversely proportional to the strength of the magnetic field. The change perpendicular to the magnetic field was greater as compared to the change parallel to the magnetic field. The volume of hits of beta particles got smaller with the increase of the magnetic field.

Conclusion: When magnetic field is increased, the decrease in the number of interactions at the outer boundaries became more pronounced in the perpendicular direction to the magnetic field. The effect of magnetic field was more apparent for higher energy beta particles than lower energy particles.
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June 2017