MWF Research Outcomes: Updating the Dosimetric Models used for SAR Compliance in the Extremities

As part of the MWF’s ongoing support for research, we recently completed a project to support an update to the dosimetric human body models used to assess SAR compliance in the extremities. Currently, Radio Frequency (RF) exposure standards as well as government regulations define different limits for the Specific Absorption Rate (SAR) induced in the body and in the extremities (or limbs). However, the numerical human body models standardised for RF exposure compliance evaluation in the IEC/IEEE 62704-2:2017 standard lack details of the body tissue definition that allow discriminating between the body and extremities, while many simulation tools allow for this evaluation provided corresponding tissue definitions are available.

Therefore, as part of the routine ‘maintenance’ update of  IEC/IEEE 62704-2:2017, we decided to develop and propose an updated model with the relevant body and extremity tissue definitions. The MWF engaged electromagnetic modelling experts Remcom to review the relevant standards and to produce updated models that can now be made available as part of the next revision of the standard.

The work resulted in detailed updates to the existing standard models, which included 14 tissue types present in the voxel meshes in the regions classified as extremity. The tissues in these extremities included: blood, blood vessel, body fluid, bone marrow, cancellous bone, cartilage, cortical bone, fat, ligament, muscle, nerve/spine, skin, toe and finger nails, and lymph and each was mapped and information provided on the relevant standard that they applied to.

The figure below shows an overview of the outcome for one of the models - with extremities defined according to the FCC, IEEE C95.1-2005, and ICNIRP standards in a different colour (although it is important to note that the IEEE C95.1-2005 extremities also include the FCC extremities and ICNIRP extremities encompass the entire arms and legs which include all the IEEE and FCC extremities).

The figure below shows an overview of the outcome for one of the models - with extremities defined according to the FCC, IEEE C95.1-2005, and ICNIRP standards in a different colour.