Monte Carlo Simulation for Small Animal Irradiation Study---Optimized Photon Energy, Beam Physics, and Nanoparticle Applications

Recent technological advances in molecular imaging have facilitated research progress in several biomedical related applications such as the targeted drug development. Many imaging instruments with high spatial resolution such as micro CT systems in molecular imaging have been developed and dedicated to small animal model study. Scientists in different research disciplines have collaborated to use these molecular imaging devices to investigate markers in molecular (or cellular) levels for disease detection, diagnosis and tumor characterization for oncology animal models. However, there has been an unbalance and shortage of research reports for the irradiation investigations in small animal models. An irradiation system specifically designed for small animals will provide a research platform to explore the fundamental tumor kinetics in the local animal environment settings and tumor response assessment after irradiation. We wish to propose a three-year grant application dedicated to the small animal irradiation study. For the first year, we plan to adapt the scientific strategy of mathematical modeling and computer simulation to understand fundamental physics for the small animal irradiator. Several physical quantities such as percentage dose distribution, dose enhancement ratios, dose conformity will be calculated. Recent commercially available nanoparticles such as gold shell particles had been used as the imaging contrast agents in small animal models. However, their potential roles in small animal irradiation have not been well identified. Therefore, in the second year of the grant proposal, we will use Monte Carlo methods to examine the characteristics of theses nanoparticles. At the end of the grant proposal, we planned to perform some preliminary experiments including does measurement using film and gel. Also beam physics of Iridium-192 and other high dose rate (HDR) radiation sources used in human clinical brachytherapy treatments will be studied at the settings of small animal irradiation environment. Overall, the optimal parameters for the hardware settings (such as irradiation beam energy, source-to-axis distance, and source-to-surface distance) will be determined from our simulation models. After the simulation phase, we will shift to build the irradiation facility platform based on the simulation results. The final goal is to fulfill the final missing link of molecular medicine technology by building a platform for small animal irradiation experiments.

Project ID:PC9808-0562
External Project ID:NSC98-2314-B182-040