Dissertation to obtain the degree of Doctor of Philosophy in Biomedical EngineeringThis thesis addresses thermal medicine applications on murine bladder hyperthermia
and brain temperature monitoring. The two main objectives are interconnected by the
key physics in thermal medicine: heat transfer. The first goal is to develop an analytical
solution to characterize the heat transfer in a multi-layer perfused tissue. This analytical
solution accounts for important thermoregulation mechanisms and is essential to
understand the fundamentals underlying the physical and biological processes
associated with heat transfer in living tissues. The second objective is the development
of target-specific models that are too complex to be solved by analytical methods. Thus,
the software for image segmentation and model simulation is based on numerical
methods and is used to optimize non-invasive microwave antennas for specific targets.
Two examples are explored using antennas in the passive mode (probe) and active mode
(applicator).
The passive antenna consists of a microwave radiometric sensor developed for rapid
non-invasive feedback of critically important brain temperature. Its design parameters
are optimized using a power-based algorithm. To demonstrate performance of the
device, we build a realistic model of the human head with separate temperaturecontrolled
brain and scalp regions. The sensor is able to track brain temperature with 0.4
°C accuracy in a 4.5 hour long experiment where brain temperature is varied in a 37 °C,
27 °C and 37 °C cycle.
In the second study, a microwave applicator with an integrated cooling system is used to
develop a new electro-thermo-fluid (multiphysics) model for murine bladder
hyperthermia studies. The therapy procedure uses a temperature-based optimization
algorithm to maintain the bladder at a desired therapeutic level while sparing remaining
tissues from dangerous temperatures. This model shows that temperature dependent
biological properties and the effects of anesthesia must be accounted to capture the
absolute and transient temperature fields within murine tissues. The good agreement
between simulation and experimental results demonstrates that this multiphysics model
can be used to predict internal temperatures during murine hyperthermia studies
