Electromagnetic Simulations and RF Safety
Pioneering the Next Generation of MRI Technology
Our research is shaping the future of medical imaging through advanced electromagnetic simulations and innovative software and hardware designs. We focus on driving transformative research initiatives, including the development of next-generation magnet designs for MR guided particle therapy, the engineering of high-performance radio frequency (RF) antennas for multi-channel MRI, and the advancement of comprehensive MR safety assessments. By bridging the gap between fundamental theoretical electrodynamics and applied engineering, we drive rapid, cost-efficient, and cutting-edge product designs in the medical physics space. We don't just simulate—we translate these numerical models into physical, high-performance hardware ready for medical imaging.
The Electromagnetic Environment in MRI
In MR systems, fields from various bands of the electromagnetic spectrum are utilized to create high-resolution images. These include a static magnetic field that polarizes the spin ensembles and switched magnetic field gradients operating at frequencies up to 10 kHz for precise spatial localization. Furthermore, radio frequency (RF) antennas generate fields at the Larmor frequency for spin excitation, and capture the MR signals.
Multiphysical Modelling, Simulation, and Optimization: Why Simulations Matter
Numerical simulations have become an indispensable tool not only for the design optimization of complex antennas but also for rigorous compliance testing. Extracting the entire three-dimensional field distribution allows us to visualize realistic exposure scenarios and gather crucial data that is impossible to measure in comparable detail. In fact, for compliance testing, the numerical computation of RF fields in high-resolution anatomical body models is currently the most practical way to obtain realistic SAR distributions required to guarantee adherence to localized SAR limits.
Because human tissue absorbs RF energy as heat, rigorous safety assessments are critical. International guidelines, such as the IEC standards, specify strict limits to prevent tissue damage, and safety assessments are generally based on the local specific absorption rate (SAR). However, since SAR only reflects the absorbed power and is not directly proportional to actual temperature rise, our approach goes a step further. We leverage advanced bio-heat transfer equations to evaluate the exact localized tissue temperature and thermal dose in addition to SAR. This comprehensive methodology ensures that the next-generation technologies we build are as safe as they are powerful.
Research Areas
Our research seamlessly integrates computational modeling, algorithmic optimization, software developing, and hands-on hardware engineering.
- Development of MR systems for MR guided Particle therapy: We are researching and developing novel magnet structures utilizing High-Temperature Superconductors (HTS). We are integrating MRI with Particle Therapy that enable real-time, high-precision image guidance during cancer treatments (Project ARTEMIS - Adaptive radiotherapy with MR-guided ion beams, funded by the Federal Ministry of Research, Technology and Space [BMFTR]).
- 14 T - The next generation of MRI: At the absolute frontier of imaging science, 14 T is the next and most powerful MRI generation ever built for human imaging. In close collaboration with the DYNAMIC consortium in the Netherlands, we are tackling the unique electromagnetic challenges of these ultra-high fields to unlock unprecedented image resolution and redefine the future of medical imaging (Project funded by DFG).
- RF Antenna Engineering for Multi-Channel MRI: Simulation-based design and optimization of advanced multi-channel RF transmitter arrays for diverse field strengths (e.g., low-field in 0.55 T and ultra-high-field in 7 T) to achieve superior image quality and homogeneous spin excitation. As part of the EU-funded project "MRexcite" we are working together with the Erwin L. Hahn Institute in Essen on the development of an integrated transmission system with 32 channels for whole-body MRI at 7 T.
- RF Safety Assessment: Enhancing traditional safety assessments by evaluating localized tissue temperature and thermal dose alongside SAR, providing a more comprehensive understanding of patient safety during complex MR examinations.
- Simulation-based compatibility testing of medical implants
- Algorithmic Optimizer Development: Creating intelligent optimization algorithms for automated antenna tuning and decoupling—an essential solution for maximizing the imaging performance and stability of complex, multi-channel coil arrays.
- Anatomical Body Models: To guarantee the precision and reliability of our electromagnetic and thermal simulations, we continuously develop high-resolution, realistic anatomical body models.
- Empirical Validation: Bridging the gap between theory and reality by conducting precise, measurement-based validations to confirm complex simulation models and results.
CST SAR Matrix Export
The DKFZ in cooperation with Dassault Systèmes shares a software to calculate SAR matrices (Q-matrices) from simulations in CST Studio Suite. Please contact Dr. Fiedler for a download link.
Publications of the group
Ready to innovate with us?
Are you looking for a dynamic environment where you can truly make an impact on cutting edge technology? We are always on the lookout for motivated students to join our research group. Whether your passion lies in coding, writing intelligent algorithms, or running complex computational physics simulations, we offer the flexibility to tailor a Bachelor’s/Master's thesis or student project that perfectly aligns with your strengths and career goals.
Send a brief message with your CV, current transcript and interest to us. Further information can be found at Teaching.
Contact
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Dr. Thomas Fiedler
Group leader
