Abstract #1308

On the measurement errors in SAR supervision introduced by directional couplers

Stephan Orzada¹, Thomas M. Fiedler¹, Jan Kesting¹, Max Joris Hubmann^2,3, and Mark E. Ladd^1,4,5,6

¹Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, ²Faculty of Electrical Engineering and Information Technology, Otto‐von‐Guericke University, Magdeburg, Germany, ³Research Campus STIMULATE, Magdeburg, Germany, ⁴Faculty of Physics and Astronomy, Heidelberg University, Heidelberg, Germany, ⁵Faculty of Medicine, Heidelberg University, Heidelberg, Germany, ⁶Erwin L. Hahn Institute for MRI, Essen, Germany

Synopsis

Keywords: Safety, Safety, SAR Supervision; VOPs

Motivation: The literature does not present a framework for quantifying the error in SAR introduced by directional couplers, which are used for online SAR supervision.

Goal(s): The goal of this work is to find a framework for quantifying the error introduced by directional couplers in online SAR supervision.

Approach: Through reformulation of the mathematical problem, we show that the measurement errors can be translated into a new set of SAR matrices that can then be compared to the original SAR matrices to calculate the relative error.

Results: The results show that the coupling within transmit arrays has a large impact on the measurement error.

Impact: This work provides a framework for calculating the measurement error in SAR calculations introduced by the directivity of the directional couplers used to measure the forward power in parallel transmit systems.

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