S.M. Abtahi - Shahid Beheshti University, Nuclear Engineering Faculty, Tehran, Iran
M. Shahriari - Shahid Beheshti University, Nuclear Engineering Faculty, Tehran, Iran
M.H. Zahmatkesh - Novin Medical Radiation Inc., Tehran, Iran
H. Khalafi - Nuclear Science and Technology Research Institute NSTRI), Tehran, Iran

Background: In gel dosimeters like other physical measurement instruments different parameters .such as sensitivity and resolution have to be evaluated However the resolution of gel dosimeter is strongly dependant to gel composition. The proper parameters and selection of optimum method in dose response readout can reduce noise and improve some important features such as contrast and spatial resolution considerably. Materials and Methods: One method for dose response readout in gel dosimetery is variation of magnetic properties of proton using magnetic resonance imaging( MRI). A major problem in this method, specially when dealing with small vials (or other gel container) is the serious reduction of contrast in edges when results in lost of dose in those region. Because of losing the spatial resolution in gel dosimetery, the image processing filters are not useful Results: In this study a new method contrast enhancement of gel dosimeter with MR image is presented. Contrast, dose error and spatial resolution in MAGICA gel dosimeter are also investigated.Conclusion: in doses lower than 17 Gy with imaging in water medium, a small reduction in spatial resolution is exchange to considerable increase of contrast in R2 map is important. In doses upper than17 Gy and importance of contrast and spatial resolution imaging in water is preferred

gel dosimeter- MAGICA- contrast- resolution- MRI