Siemens MAGNETOM Avanto Operator's Manual page 119

SAR monitoring
MAGNETOM Avanto, MAGNETOM Verio | syngo MR E11
Print No. MR-01501G.621.02.02.02
Depending on the medical question, different coils are used for the
RF transmission (for example, head, extremity or body coil). The
different coils lead to different RF exposure situations for the patient.
Therefore, different SAR quantities and corresponding limits have
been established (for example, head SAR, whole body SAR, local SAR,
and SAR of the exposed part of the body). According to the guideline
for monitoring SAR, the software automatically determines the SAR
quantities to be monitored and applies the corresponding limits. For
the actual RF exposure situation, one of the above-mentioned SAR
quantities will show the highest "value to limit ratio". For example, in
the case of a head examination with a typical head coil, this will be
the global head SAR. If however, a transmitting coil with an
inhomogeneous RF field is applied, this will be the local SAR.
SAR limits are observed by a software monitoring function.
Look Ahead monitoring: Prior to each measurement, the values of
the SAR quantities to be observed are calculated (always as worst-
case values) and compared with the corresponding limit values. If one
of the calculated SAR values exceeds the corresponding limit, the
measurement cannot be started. The following dialog box appears at
the syngo Acquisition Workplace: SAR Limit(s) Exceeded!

To ensure accurate calculation of the SAR values, the weight and
height of the patient must be entered correctly during
registration.
MR system operation 5
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