Noninvasive detection and prediction method for temperature in ex vivo biological tissue based on opto-thermal-acoustic co-coupling

Significance: Photothermal therapy is a minimally invasive technique that utilizes near-infrared light to induce localized hyperthermia for the selective ablation of cancer cells. Its therapeutic efficacy is highly dependent on precise temperature regulation. Aiming at the problems of invasiveness, insufficient penetration depth existing in current temperature monitoring technologies, we propose an innovative solution. Aim: We propose a method that can be used to monitor the temperature inside ex vivo biological tissues during laser heating. Approach: By constructing an optothermal-acoustic multiphysics coupling model and combining it with our designed dual-optical path co-coupled photoacoustic-photothermal temperature monitoring system, noninvasive observation of the internal heat source distribution in tissues is achieved. On this basis, theoretical data and real data are fused to realize precision measurement of the temperature in the lesion area and adjacent tissues. Result: The results of ex vivo experiments show that this method achieves heat source intensity estimation with an error of less than 3.5% in ex vivo tissues at the millimeter to centimeter depth range, and the temperature measurement error at multiple different validation sampling points is within 0.25°C. Conclusion: The proposed method and system in this study can calculate the temperature inside ex vivo tissues during laser heating, offering a broader temperature measurement range compared with conventional photoacoustic thermometry. This method possesses certain academic value and is expected to provide technical reference for the research on target temperature sensing during photothermal treatment.