A Core Body Temperature Retrieval Method for Microwave Radiometry when Tissue Permittivity is Unknown.
A Core Body Temperature Retrieval Method for Microwave Radiometry when Tissue Permittivity is Unknown.
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当组织介电常数未知时微波辐射测量的核心体温反演方法。
DOI：
10.1109/jerm.2022.3171092
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发表时间：
2022
影响因子：
--
通讯作者：
Kiourti,Asimina
中科院分区：
文献类型：
--
作者：
Tisdale,Katrina;Bringer,Alexandra;Kiourti,Asimina
本文提出了一种新的方法，用于核心温度反演时，人体组织层的复介电常数和传热参数未知的微波辐射测量。以前的工作提出了核心温度反演的方法，但这些方法没有考虑相关电磁和热参数的群体变化，这可能会增加测量误差，超过临床可接受的0.5 °C限值。Pennes的六层人体头部模型的生物热模型结合相干电磁模型模拟实验数据。为了恢复核心温度，然后使用非线性最小二乘优化来最小化模拟实验数据与物理温度的指数模型和相干电磁模型之间的差异。通过使用20个频率从1-5 GHz，核心温度检索，同时占人口的介电常数和热参数的变化。蒙特卡罗模拟，其中的热参数和介电常数根据文献推导，人口代表性的分布和核心体温从18到46 °C变化，用于评估检索方法的效用。不同的天线方向图进行了测试，以探讨对检索精度的影响。该反演方法在仅热参数未知时的反演误差<0.1 °C，在热参数和介电常数未知时的反演误差<0.5 °C，在临床可接受的0.5 °C误差范围内。这些结果有助于医学微波辐射测量领域的进展，使其成为一种临床上可行的无创测量方法，在测量所有患者时都是准确的。
This paper presents a novel method for core temperature retrieval using microwave radiometry when complex permittivity and heat transfer parameters of the tissue layers of the human subject are unknown. Previous works present methods for core temperature retrieval, but these methods do not account for population variation in the relevant electromagnetic and thermal parameters, which can increase measurement error beyond the clinically acceptable limit of 0.5 °C. Pennes’ bioheat model of a six-tissue-layer human head model combined with a coherent electromagnetic model simulate experimental data. To retrieve core temperature, nonlinear least squares optimization is then used to minimize the difference between the simulated experimental data and an exponential model for physical temperature and the coherent electromagnetic model. By using 20 frequencies spanning from 1-5 GHz, core temperature is retrieved while accounting for population variation in the permittivity and thermal parameters. A Monte Carlo simulation in which the thermal parameters and permittivity vary according to literature derived, population-representative distributions and the core body temperature varies from 18 to 46 °C is used to assess the utility of the retrieval method. Different antenna patterns are tested to explore the effect on retrieval accuracy. The retrieval method has a retrieval error of <0.1 °C when only the thermal parameters are unknown and a retrieval error of <0.5 °C when the thermal parameters and permittivity are unknown, which is within the clinically acceptable error range of 0.5 °C. These results help progress the field of medical microwave radiometry toward being a clinically viable noninvasive measurement that is accurate when measuring all patients.