9634110 Anvari In many therapeutic applications of lasers, it is desirable to induce photothermal destruction of subsurface targeted structures without damaging the overlying tissue. For example, successful laser treatment of certain skin disorders such as port wine stains (PWS), and hemangiomas requires selective destruction of subsurface targeted blood vessels while protecting the normal, overlying skin structures from thermal injury. The objective of the proposed research is development and optimization of cryogen spray cooling (CSC) to deliver short spurts of a cryogen (on the order of milliseconds) in conjunction with laser irradiation to protect superficial skin structures from thermal injury, while achieving photothermal destruction of subsurface targeted blood vessels. Further development of CSC in conjunction with laser irradiation will provide substantial relevant data to investigators interested in therapeutic procedures utilizing the laser or other radiative sources to induce spatially selective thermal damage in multi-layered composite structures. The specific objectives of this proposal are: 1) development of mathematical models to assist in optimization of CSC and laser irradiation parameters; 2) in-vivo, and in-vivo experimentation using collagen film and chicken comb models, respectively, to verify accuracy of the mathematical modeling, and demonstrate utility of CSC in conjunction with laser irradiation for spatially selective thermal damage; 4) design and construction of a compact, and portable prototype instrument to: a) allow delivery of cryogen and laser light through an optical fiber; and b) perform diagnostic measurements that determine depth of targeted blood vessels prior to selection of appropriate CSC and laser irradiation parameters; and 5) expansion of the Bio- and Biomedical-Engineering (BBME) concentration at Harvey Mudd College (HMC) engineering department. The preceding tasks will be accomplished through a joint effort with the Beckman Laser Institute and Medical Clinic (BLIMC) at University of California, Irvine (UCI). Scientists at BLIMC will collaborate on the development of a diagnostic procedure to determine depth or subsurface chromophores. Furthermore, facilities and instrumentation necessary for successful completion of the proposed research are available at BLIMC. The educational objectives will be achieved by student participation in algorithm and instrumentation development, in-vitro experimentation. The interdisciplinary nature of the project will allow development of educational materials for BBME courses at HMC that would include such topics as biomedical optics, heat transfer, laser-tissue interactions, biomedical instrumentation, and numerical optimization techniques. ***
