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The body is largely cosopmed of water molecules which each contain two hydrogen nuclei or protons. When a person goes inside the powerful magnetic field of the scanner, the magnetic moments of these protons align with the direction of the field.A radio frequency electromagnetic field is then briefly turned on, causing the protons to alter their magnetization alignment relative to the field. When this field is turned off the protons return to the original magnetization alignment. These magnetization alignment changes create a signal which can be detected by the scanner. The frequency at which the protons resonate depends on the strength of the magnetic field. The position of protons in the body can be determined by applying additional magnetic fields during the scan which allows an image of the body to be built up. These are created by turning gradient coils on and off which creates the knocking sounds heard during an MRI scan.
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(VISITOR) AUTHOR'S NAME
Icha
MESSAGE TIMESTAMP
17 december 2014, 08:43:50
AUTHOR'S IP LOGGED
158.85.49.234
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