ACTA

Temperature Measurement Using Passive Harmonics during High Intensity Focused Ultrasound Exposures in Porcine Tissue

Hu Dong^{a, b}, Shengyou Qian^a, Qiaolai Tan^a, Xiao Zou^a, Bei Liu^a
^aCollege of Physics and Information Science, Hunan Normal University, Changsha 410081, PR China
^bDepartment of Information and Engineering, Changsha Normal University, Changsha 410100, PR China

Received: February 26, 2018; in final form July 14, 2018

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It is important to deliver suitable thermal dose to target region during high intensity focused ultrasound therapy,and ultrasonic non-invasive temperature measurement is an easily accepted approach to monitor the temperature fields during the treatment process. Traditional method usually required another source for monitoring besides high intensity focused ultrasound source. This paper was based on passive scattering harmonics for high intensity focused ultrasound temperature measurement, and it could avoid the influence of treatment sources on temperature measurement. The purpose of this paper is to investigate the relationship between the nonlinear harmonic amplitude and temperature in porcine tissue (muscle and liver). The optical fiber hydrophone was used to receive passive scattering harmonics from high intensity focused ultrasound irradiation in porcine tissue, and the temperature of tissue in focal region was measured with a thermocouple needle at the same time. The relationship between harmonic amplitude and temperature was analyzed. Experimental results indicate that the values of amplitude for fundamental wave P₁, the second harmonic P₂, the third harmonic P₃, the ratios of P₂/P₁, P₃/P₁, and P₃/P₂ decrease while temperature increases in the focal region of porcine tissue, and the slope of P₂/P₁, P₃/P₁, and P₃/P₂ have obvious decline at the beginning of temperature measurement, but their slope become flat as temperature increases, and the slope of P₂/P₁, P₃/P₁, and P₃/P₂ drop faster in porcine muscle than in liver. This study may potentially be used as an non-invasive method of temperature monitoring for ultrasonic thermal therapy in real-time.

DOI:10.12693/APhysPolA.134.524
topics: high intensity focused ultrasound, temperature measurement, passive harmonic