Editing Specific absorption rate (section)

=== MRI scanner SAR testing ===
For [[magnetic resonance imaging]] the limits (described in [http://webstore.iec.ch/Webstore/webstore.nsf/artnum/043851?opendocument IEC 60601-2-33]) are slightly more complicated:

{| class="wikitable" style="text-align: center;"
|-
| 
! Whole-body SAR
! Partial-body SAR
! Head SAR
! colspan="3" | Local SAR (a)
|-
! Body region →
| whole body
| exposed body part
| head
| head
| trunk
| extremities
|-
! Operating mode ↓
| (W/kg)
| (W/kg)
| (W/kg)
| (W/kg)
| (W/kg)
| (W/kg)
|-
! Normal
| 2
| 2–10 (b)
| 3.2
| 10 (c)
| 10
| 20
|-
! 1st level controlled
| 4
| 4–10 (b)
| 3.2
| 20 (c)
| 20
| 40
|-
! 2nd level controlled
| &gt;4
| &gt;(4–10) (b)
| &gt;3.2
| &gt;20 (c)
| &gt;20
| &gt;40
|-
! Short-duration SAR
| colspan="6" | The SAR limit over any 10 s period shall not exceed two times the stated values
|}
: '''Note''': Averaging time of 6 minutes.
: (a) Local SAR is determined over the mass of 10&nbsp;g.
: (b) The limit scales dynamically with the ratio "exposed patient mass / patient mass":
:: Normal operating mode: Partial body SAR = 10&nbsp;W/kg − (8&nbsp;W/kg × exposed patient mass / patient mass).
:: 1st level controlled: Partial body SAR = 10&nbsp;W/kg − (6&nbsp;W/kg × exposed patient mass / patient mass).
: (c) In cases where the orbit is in the field of a small local RF transmit coil, care should be taken to ensure that the temperature rise is limited to 1&nbsp;°C.