Temperature distribution analysis using a combination of near-infrared laser, gold nanorods, and surface cooling equipment

Metastatic diseases are the primary causes of death among cancer patients. Photothermal therapy, which combines near-infrared lasers, gold nanorods (GNRs), and skin surface cooling equipment, is a promising local treatment for breast cancer, as well as head and neck cancer. However, in this treatment, accurate predictions of the temperature distributions within organisms and uniform distributions of GNRs within tumors are often difficult. This study focused on evaluating composite heat transfer characteristics when laser irradiations were combined with GNRs, and a surface cooling method was applied. The temperature distributions were analyzed using agar as a bio-simulated material. The experimental results revealed that the combination of laser irradiation, GNR injection, and surface cooling could achieve higher temperatures near the GNR injection sites at low surface temperatures. The obtained temperature distributions were quantitatively analyzed using the thermal damage function. When the laser power was set to create a tumor area temperature greater than 45 °C, the tumor area could be treated without causing skin damage when injecting GNRs into the tumor area and cooling the surface. This study demonstrates the effectiveness of this therapy in local treatments of cancer.