30 Icon System Manual T02985_02_03
Safety (English)
3.6.2 Gradient Fields
Faraday's law (law of induction) establishes a relationship between the changes of a
magnetic field over time and an electrical rotational field. The frequency change of the
magnetic flux (switching on and off the gradient fields) induces an electrical field in the
tissue that shifts the charge in the nerve fibers of the tissue. This shift in charge dissipates
the resting membrane potential of the nerve fibers and my lead to peripheral nerve
stimulation. Currents induced inside conductors can also in-crease the local temperature
considerably (hot-spots).
Risk of peripheral nerve stimulation.
Never enter with your extremities inside the gradient coil while the system is
scanning.
Risk of burn injuries.
Do not touch the inner surface of a gradient coil during or shortly after running a
gradient sequence. Surface temperatures might cause burn injuries.
Do not enter the gradient field wearing conductive materials.
Risk of overheating of animals.
High duty cycle gradient schemes applied for a long duration lead to high temperatures at
the inner surface of the gradient coil. Depending on the animal setup and the remaining
air circulation, a lethal heating of the animal can occur.
Monitor and control the body temperature of the animal under investigation.
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