Temperature monitoring utilising thermoacoustic signals during pulsed microwave thermotherapy: A feasibility study

Figures & data

Figure 1. An experimental set-up schematic of pulsed microwave thermotherapy and in situ temperature monitoring system. The coupling medium between sample and transducer is oil in a plastic bag.

Figure 2. Peak thermoacoustic pressure induced in water with various temperatures. The triangle represents experimental data and the circles are the Grüneisen coefficient. The solid line is the fitting curve of experimental data versus temperature while the dashed line is a fit to literature data [31].

Figure 3. Waveforms of the microwave-induced acoustic pressure for water at various temperatures.

Figure 4. (A, B and C) Dependence of the thermoacoustic pressure on the temperature, which shows goodness fit for linear regression. The test sample was freshly excised pork liver. The PRF is 15 Hz, 25 Hz, 35 Hz, respectively. R², goodness of fit. (D) Relationship between the rise of temperatures in ex vivo tissue and the pulse repetition frequency. The average power corresponding to the used PRF is 2.7 W, 4.5 W and 6.3 W respectively.

Figure 5. The calculated values (triangle) from thermoacoustic signals versus actual temperature recorded by a digital thermometer. The solid line represents the line of unity.

Figure 6. Pulsed microwave-induced acoustic pressure versus heating time with a pulse repetition frequency of 35 Hz. The inset image shows a sample made of agar and Fe₃O₄ particles.

Shah J, Park S, Aglyamov S, Larson T, Ma L, Sokolov K, Johnston K, Milner TS, Emelianov Y. Photoacoustic imaging and temperature measurement for photothermal cancer therapy. J Biomed Opt 2008; 13: 1–13

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