Theoretical Simulation of Temperature Elevations in Tumors Using Monte Carlo Method and Comparison to Experimental Measurements During Laser Photothermal Therapy

Nanotechnology using gold nanoshells or nanorods is a newly developed hyperthermia approach and has been tested in the past several years in cancer treatment.^1–2 Gold nanorods have a diameter of ∼10 nm and an aspect ratio of approximately four. By varying the geometric ratio, the nanostructures can be tuned to have strong absorption and scattering to a specific laser wavelength. Designing an optimal treatment protocol of laser photothermal therapy requires understanding of gold nanorod deposition inside the tumor after injection, its resulted specific absorption rate (SAR) distribution, and the ultimate temperature field in the tumor during the treatment. Recent microCT studies by our group have suggested that the gold nanorod solution injected into PC3 prostatic tumors results in an almost uniform distribution of the gold nanorods in the tumors.³ The Monte Carlo method has been used in the past to determine the heating pattern (SAR) of laser-tissue thermal interaction.⁴ However, the accuracy of the theoretical simulation of the temperature fields in tumors relies on precise measurements of the optical properties of the tumors with nanorods presence.