Four quadrant gradient magnetic field coils are typically used in magnetic resonance imaging (MRI) systems to generate gradient magnetic fields in all three dimensions (x, y, and z). These coils are designed to produce varying magnetic fields across the imaging volume, enabling spatial encoding of the MR signal, which is crucial for producing detailed images of the body.
Each coil set consists of multiple individual coils arranged in a specific configuration to generate gradients along the x, y, and z axes.
The specific design and arrangement of these coils can vary depending on the MRI system manufacturer and the desired imaging specifications. They are often constructed using copper wire wound around cylindrical or rectangular forms and placed strategically within the MRI machine to produce the desired gradient fields.
Overall, the four quadrant gradient magnetic field coils work together to produce precise spatial encoding of the MR signal, allowing for the creation of detailed images with high resolution and contrast.
https://mriquestions.com/x--and-y--gradients.html
is a good exemple. If you want more details, you may find then in patent papers.
Maillot Patrice
Thank you very much.
This is a relevant source.
I am particularly interested in the design and structure of Golai saddle coils. How did that type of coil come about, and how is the gradient magnetic field they create determined? Where could I get it?
20 years ago, I visited the Siemens factory in Erlangen. Taking pictures is not allowed...
https://www.jpier.org/issues/volume.html?paper=15072306
Article Design and fabrication of a new multi-loop saddle coil for 1.5 T MRI
Article Optimization of saddle coils for magnetic resonance imaging
etc
Maillot Patrice
Thank you very much!
These works will benefit me.
Why is taking pictures not allowed?
Can they be used by citing the Creative Commons license?
The second citation is for a rf coil, not a gradient coil. It is a design that has been used for a long time. Sets for this design (then termed Golay coils), as in the first citation) can be used for X and Y gradients (so combined with a Maxwell coil pair for the Z gives the three main axis).
How the coils interact with the magnet, magnet shim coils and the eddy currents this produces are a function of how they are driven, shielded, etc.
BioMedical Magnetic Resonance Technology (Chen and Hoult 1989 - ISBN 0-85274-118-9) has a good introduction to this.
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