Tissue temperature distribution measurement and laser immunotherapy for cancer treatment

Abstract

Temperature distribution in tissue can be a crucial factor in laser treatment for inducing immunization responses. In this study, Magnetic Resonance Imaging (MRI) was used to measure thermal temperature distribution in target tissue in laser treatment of metastatic tumors. It is the only feasible method for in vivo, non-invasive temperature distribution measurement. The measurement was conducted using phantom gel and tumor-bearing rats. The thermal couple measurement of target temperature was also was used to calibrate the relative temperature increase. The phantom system was constructed with a dye-enhanced spherical gel embedded in uniform gel phantom, simulating a tumor within normal tissue. Irradiation by an 805-nm laser increased the system temperature. Using an MRI system and proper algorithm processing for small animal studies, a clear temperature distribution matrix was obtained. The temperature profiles of rat tumors, irradiated by the laser with a power in the range of 2-3.5W and injected with a light-absorbing dye, ICG, and an immunoadjuvant, GC, were obtained. The temperature distribution provided in vivo thermal information and future reference for optimizing dye concentration and irradiation parameters to reach the optimum tumor destruction and immunization effects.