Interstitial laser immunotherapy (ILIT) is designed to use photothermal and immunological interactions for treatment of metastatic cancers. The photothermal effect is crucial in inducing anti-tumor immune responses in the host. Tissue temperature and tissue optical properties are important factors in this process. In this study, a device combining interstitial photoacoustic (PA) technique and interstitial laser photothermal interaction is proposed. Together with computational simulation, this de