Magnet PolarityWhich end of a scanner is the north or south pole?
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South and North poles
For convenience and standardization (but really no other good reason), the patient table end of a scanner is usually taken to be the South pole and the far back "service" end the North pole. The direction of the Bo field is therefore from front (−Z) to back (+Z) along the bore of the scanner. However, this is an entirely arbitrary choice and could vary by installation.
In the past clinical scanners had relatively large fringe fields, and when two or more scanners were sited near each other in a facility, some consideration had to be given to the polarity of each magnet. In these situations magnetic fringe fields and interactions were minimized by configuring the magnets so that the unlike poles faced each other. In the modern era with self-shielded scanners, this is not a significant issue for most clinical sites. However, with very high field (7+ Tesla) human and animal scanners now clustered together in research facilities, pole orientation may still be a planning consideration.
In the past clinical scanners had relatively large fringe fields, and when two or more scanners were sited near each other in a facility, some consideration had to be given to the polarity of each magnet. In these situations magnetic fringe fields and interactions were minimized by configuring the magnets so that the unlike poles faced each other. In the modern era with self-shielded scanners, this is not a significant issue for most clinical sites. However, with very high field (7+ Tesla) human and animal scanners now clustered together in research facilities, pole orientation may still be a planning consideration.
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