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Finite element simulation of photoacoustic imaging of gastric tissue and the related tumor

Photoacoustic imaging (PAI) has recently emerged as a promising imaging modality for gastric cancer. In order to describe and study photoacoustic (PA) signal generation principles and study the effect of variation in PA parameters. This paper presents a finite element (FE)-based numerical simulation model of PAI of gastric tissue and the related tumor. This study attempts to describe how a commercially available Finite Element software (COMSOL), can serve as a single platform for simulating PA that couples the electromagnetic, thermodynamic and acoustic pressure physics involved in PA phenomena. A three-dimensional optical model of uniform gastric tissue embedded with spherical tumor and external irradiation short pulse laser point source was constructed. Four sets of simulation models were integrated together to describe the physical principles of PAI: 1) Diffusion equation was used to describe light propagation; 2) Temperature changes were simulated using bio-thermal equations; 3) With stress-strain model, the process of the PA signal generation could be simulated; 4) Pressure acoustics was used to simulate the propagation of acoustic pressure. In addition, point probes placed in the interior and boundary of the FE model can provide acoustic pressure data, which conforms to the rules of PA signal. This study not only confirm the effectiveness of the PA model, but also provide certain significance for better excitation and detection of PA signal.