Thermal strain between ultrashort laser pulse and tumor using finite element analysis

Photoacoustic imaging technology is an emerging functional imaging method in the field of biomedical applications. It combines the light absorption characteristics of tissues with the advantages of ultrasonic detection, and has the advantages of strong contrast, high sensitivity, and deep imaging depth. Therefore, this article uses the finite element software COMSOL Multiphysics to study the thermal expansion process of the photoacoustic effect caused by the interaction of ultrashort laser pulses with tissues. In COMSOL, a laser with a pulse width of 5 ns and a wavelength of 532 nm is used as the excitation light source. Use mathematics module, heat transmission module, solid mechanics module and pressure acoustics module to simulate the process of photothermal conversion-thermal expansion-generation of ultrasound in the photoacoustic imaging of the Gastric tissue-tumor system. In this way, the photoacoustic signal and its image are obtained. This research focuses on exploring the thermal expansion process in the photoacoustic effect.