Development of a Numerical Model for Microbubble Enhanced Treatment in HIFU Therapy

Development of a Numerical Model for Microbubble EnhancedTreatment in HIFU Therapy High Intensity Focused UltrasoundHIFUis currently utilized in several modern therapeutic and surgical medical applicationssuch as for tissue ablation in the treatment of cancer and for benign prostatic hyperplasiaThe HIFU research frontier has now moved toward the treatment of deep seated solid tumors such as in liver and brain cancers because HIFU is a truly noninvasive form of localized ablative therapyTo eliminate pre focal damage due to induced cavitation activity along the pathwaymicrobubbles used as ultrasonic contrast agents have been proposed to be injected into the targeted region to promote heating through controlled bubble dynamics activity in the focal regionwhile reducing the HIFU source intensityThe behavior of such injected microbubbles and their interaction with the acoustic field has not been fully investigated experimentally or numerically due to the complex nonlinear interactions between the oscillating bubbles and the ultrasoundIn this SBIR Phase II effortcontinuation of the development of a novel numerical approach is proposed to help accurately characterize the acoustic and thermal field in microbubble enhanced HIFU under various conditionsThe numerical approach employs an EulerianLagrangian approach in which the bubbles are tracked in a Lagrangian fashionwhile the acoustic and thermal fields are resolved using a fixed grid Eulerian continuum approachThe heat deposition in the HIFU focal regioncontributed by both the ultrasound acoustic waves and the bubble oscillationswill be modeled by solving heat transport equationsThe two way coupling allows to predict the nonlinear acoustic field and bubble behaviors accurately and accounts for both bubble bubble and bubble fluid interactionA multi level parallelization algorithm using both Graphic Processing UnitGPUand Central Processing UnitCPUcomputation technology will be implemented to speed up the computationsThe developed numerical model has been successfully validated against experimental data available in the literature during Phase IIn Phase II in vitro and ex vivo experiments using machine perfused pig liver will be conducted at the University of Washington for further in depth validationThese will form an important stepping stone for future large animal studies followed by clinical trialsThe resulting product will be a computational tool useful to help researchers develop efficient microbubble enhanced HIFU for the treatment of deep seated solid tumorsThe tool will be also utilized by HIFU instrument manufacturers to selectusing parametric studiesefficient and safe designs and by medical researchers to design proper HIFU treatment protocol for cliniciansThe software will also be applicable to the modeling of other controlled cavitation bubbles such as those generated by shock wave lithotripter The resulting product will be a computational tool useful to help researchers develop efficient microbubble enhanced HIFU for the treatment of deep seated solid tumorsThe tool will be also utilized by HIFU system manufacturers to selectusing parametric studiesefficient and safe designs and by medical researchers to design proper HIFU treatment protocol for clinicians