Specific Absorption Rate Optimization in Microwave Cancer Hyperthermia via Local Power Synthesis Algorithm

. 2025 Aug 28;17(17):2813. doi: 10.3390/cancers17172813

Algorithm 2 Adaptive Threshold Search for APA Optimization

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Inputs: Electric field matrix $[E_{N}]$ , input power $P_{0}$ , reference input resistance $R_{0}$ , tumor region $T$ with radius $r_{t}$ , healthy region $H$ with radius $r_{h}$
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Fixed Gaussian peak amplitude $A_{0}$ at tumor center $(x_{t}, y_{t}, z_{t})$ with the maximum achievable intensity
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Candidate set ${t h_{u p}^{(i)}}$ to control hotspot suppression
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Outputs: Optimal excitation vector ${[\tilde{b}]}^{★}$ and selected threshold $t h_{u p}^{★}$
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Determine the dominant polarization component $ν$ of $[E_{N}]$
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for each $t h_{u p}^{(i)}$ in candidate set do
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Compute standard deviation $σ_{0} = r_{h} {(2 log (A_{0} / t h_{u p}^{(i)}))}^{- 1 / 2}$
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Compute $t h_{l o w}^{(i)} = A_{0} \cdot exp (- r_{t}^{2} / (2 σ_{0}^{2}))$
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Construct Gaussian field $[E_{t}]$ with parameters $A_{0}$ and $σ_{0}$ and polarization $ν$
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Run APA Optimization (Algorithm 1) with $([E_{t}], t h_{l o w}^{(i)}, t h_{u p}^{(i)})$
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Compute metrics $V_{10 %}^{H}$ and $V_{50 %}^{H}$
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Store results in $Q (t h_{u p}^{(i)}, V_{10 %}^{H}, V_{50 %}^{H})$
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end for
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Identify $t h_{u p}^{★}$ via Pareto trade-off between $V_{10 %}^{H}$ and $V_{50 %}^{H}$
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Return corresponding excitation vector ${[\tilde{b}]}^{★}$