Outline of the module
This module provides a theoretical and practical guide to RF coil design. After introducing the required mathematical concepts and the theoretical engineering foundations the module starts with an introduction to resonant circuits and well known RF coil implementations. Based on the theoretical framework tools for electrical circuit analysis and full wave electromagnetic simulations will be introduced and applied to a simple realistic RF coil design tasks. Advanced topics such as multi-tuned coils and phased arrays will be introduced and possible implementations will be verified through simulations. The last part of the module will touch safety relevant information for coil builders such as specific absorption rate (SAR), the concept of integrated safety for medical devices and other relevant issues.
The module covers the following topics:
• Designing resonating circuits
• Building a basic RF coil
• Matching and tuning an RF coil on the bench
• Estimating SAR and SNR of an RF coil
• Designing phased arrays and double-resonant coils
• What is relevant for safety in RF coil development?
Learning objectives
At the end of this module, students will have knowledge of:
• Basic mathematical description of RF coil circuit elements
• Basic theory of resonant circuits
• Basic theory of 3D electromagnetic simulations
• Basic components of an RF lab and tools required for coil building
• Software packages for RF coil design
• Different concepts of volume coils
• Advanced concepts of multi-element coils
• Coils for multiple nuclei
• Fundamental knowledge of RF safety concepts
Content
The module will introduce the basic theory and practical knowledge required to design RF coils for MR imaging experiments. It covers the high frequency behaviour of lumped and distributed elements and their combination to form a resonant circuit. The issues of impedance matching for maximum power transfer during transmission and minimum noise degradation during reception will be explained. Additional circuits such as baluns, cable traps and PIN diode circuits are introduced and their purpose is illustrated. The module covers advanced coil design using circuit and 3D field simulations and explains the theory behind the simulation methods. It demonstrates the application of these tools for a realistic coil design task. A simple coil will be constructed and used to illustrate the laboratory equipment required to design coils (network analyser, noise figure analyser, oscilloscope, etc.) as well as explain the use of simple bench test equipment like pickup loops and other lab equipment.
The module will also introduce standard software packages for coil design and simulation of performance parameters. It will show how to use these for RF circuit design as well as how to obtain ideas about SNR and SAR performance. The software packages will also be used to analyse standard coil architectures like birdcage coils, TEM coils and phased arrays for transmission and/or reception. The theoretical part will be concluded by presenting the special requirements for x-nucleus imaging and dual tuned resonators.
This module will try to answer these questions in form of lectures, and in practical sessions in which they implement mathematical algorithms and apply them to common problems in RF coil design.
Overview of tasks and lectures
There will be 10 lectures of 2 hours distributed over 5 days.
• Introduction to RF coils
• Mathematical Foundations
• Theory of RF circuit design
• Components of an RF circuit in MRI
• Hardware for RF testing
• Simulation software: SAR and SNR
• Solenoids vs. Volume Coils
• Phased Arrays
• RF at Ultra-High Field Strength (pTX)
• Advanced Concepts: X-Nuclei, Multi-tuned Coils, Travelling Waves
Position within the programme
This is a unique module in this Master programme dealing with the theory and electronics needed for radiofrequency signal transmission and reception in MRI. This module is complementary to the general modules dealing with MRI physics, Ultra High-Field MRI, and MRI sequences.
Teaching format
Structure
The module is a one week-long residential module consisting of 10 lectures of 2 hours. Each day, the students will in addition perform implementation of computer algorithms relevant to one the lecture topics guided by tutors. Furthermore, the residential part is combined with a preparatory reading phase and post-module marked assignments corresponding in total to 12 additional ECTS.
Grading
Passing the module requires an 85% attendance to the lectures and practical sessions, and a satisfactory completion of the practical sessions and the module assignments. The module assignments will be summarised by the students in a written form which will be evaluated by the module coordinator(s).