基于超声衰减系数的微波热疗无损测温

Noninvasive temperature estimation of microwave hyperthermia based on ultrasound attenuation coefficients

目的热疗的引导、疗效及剂量控制都需要温度监测,本文旨在探索一种基于超声衰减系数的微波热疗无损测温新方法。方法利用水浴加热实验系统,以新鲜体外猪肝组织为研究对象,通过采集不同温度下的超声原始回波信号,分析不同温度下组织的超声衰减系数,建立超声衰减系数与温度相关性模型,用于微波加热实验过程中温度的检测。结果超声衰减系数与温度相关性模型为:超声衰减系数=0.513×温度-0.80。超声衰减系数在微波热疗低温段(≤50℃)测温误差较小(<5℃),在高温段(>50℃)测温误差较大(>10℃)。结论超声衰减系数可用于常规热疗无损测温。微波热疗温度分布不均使得检测较为困难。利用正常与热凝固组织超声衰减系数的差异进行热凝固区的检测具有一定优势。

Objective Temperature monitoring is essential for hyperthermia guidance,treatment efficacy and thermal dose control The objective of this study is to explore a new method for noninvasive temperature estimation of microwave hyperthermia based on ultrasound attenuation coefficients （UAC）.Methods In this study,water bath heating experiments were performed to fresh in vitro porcine liver tissues,and the original ultrasonic echo signals at different temperatures were collected.The UAC of porcine liver tissues at different temperatures were analyzed,and the correlation between UAC and temperature was derived for temperature estimation in microwave heating experiments.Results The correlation between UAC and temperature was：UAC =0.513 × Temperature-0.80.Temperature estimation based on UAC for microwave hyperthermia had a smaller error （＜5℃） in the temperature range of ≤50℃,and a bigger error （＞ 10℃） in the temperature range of ＞ 50℃.Conclusions The UAC might be used for noninvasive temperature estimation of mild hyperthermia.It was difficult to accurately estimate the temperature because of the heterogeneity of temperature distribution in microwave hyperthermia.It might be a potential approach for detecting thermal coagulation zones based on the difference between the UAC of normal and coagulated tissues.