Browsing by Subject "Electromagnetic simulations"

Now showing 1 - 3 of 3

Open Access
FEM Based design and simulation tool for MRI birdcage coils Including eigenfrequency analysis
(2012) Gürler, Necip; İder, Yusuf Ziya
Radio Frequency (RF) birdcage coils are widely used in Magnetic Resonance Imaging (MRI). Before the actual construction of the coil, not only calculating the capacitance value, which is necessary for the coil to resonate at the desired frequency, but also modeling the birdcage coil in a 3D simulation environment and making electromagnetic analysis in the volume of interest have importance in terms of observing the resonance behavior of the coil, electromagnetic field distributions inside the coil, or specific absorption rate (SAR) distribution for any object. For this purpose, we have made two different electromagnetic analyses of low-pass and high-pass birdcage coils in COMSOL Multiphysics. These are frequency domain analysis and eigenfrequency analysis. We have also developed a software tool using MATLAB® to make these electromagnetic analyses easily and according to the userspecified parameters. Simulation results for these analyses are provided. For the experimental results, we have constructed a hand-made lowpass birdcage coil and measured the resonant modes of the coil for different capacitance values. Our eigenfrequency analysis tool calculates the resonant modes with high accuracy
Open Access
Log-periodic antenna design using electromagnetic simulations
(IEEE, 2003-06) Ergül, Özgür; Gürel, Levent
It is essential to complement theoretical antenna design recipes with the numerical results obtained from electromagnetic simulations. As such, the benefit of such a hybrid procedure is demonstrated by using the design of an LP antenna as a case study. It is shown that significant performance improvements can be obtained by applying corrections shown by the simulation results.
Open Access
Optimized RF safety monitoring for cerebellar magnetic resonance imaging at 7T
(2024-09) Mahmoudalilou, Elnaz Mahmoudi
The primary objective of this thesis is to develop optimized RF safety assessment techniques for cerebellar imaging using 7T MRI systems, with a specific focus on Spinocerebellar Ataxias (SCAs). Due to the unavailability of detailed electro- magnetic simulation data from the manufacturer, this study focused on predicting the electromagnetic behavior of the Nova 8Tx/32Rx coil’S 8 pTx channels to en- sure accurate and safe imaging. Accurate prediction of the coil’s electromagnetic performance is essential for both RF safety and imaging quality, particularly in managing RF exposure and minimizing tissue heating. The approach involved replicating the electromagnetic fields of the Nova coil through simulations, validating these predictions against experimental measure- ments, and implementing an algorithm for calculating the temperature-based Virtual Observation Points (tVOPs) in future works for rapid RF safety assess- ments. While the initial simulations captured key aspects of the coil’s B1+ field distribution, discrepancies between predicted and experimental results revealed challenges, especially in random-phase shimming configurations. The limitations of using ideal current sources and the reduced dataset for optimization highlighted the need for more comprehensive data and realistic models. The findings underscore the importance of integrating empirical measurements with refined simulations to bridge the gap between theoretical models and real- world performance. Future work should focus on enhancing current source mod- els, mitigating noise and experimental inaccuracies, and expanding the applica- tion of these techniques to broader clinical scenarios. By addressing these chal- lenges, this research can contribute to improving both the safety and quality of high-field MRI, ultimately advancing its reliability for both clinical and research applications.