Implantable wireless micro-devices for enhancing radiation treatment efficacy

Radiation therapy administered with surgery and/or chemotherapy is a powerful method to treat cancer. Effective radiation therapy requires a multidisciplinary effort from several fields such as physics, mathematics, computer science, and radiation biology. Among the important parameters for an effective treatment one can include: (1) verification of the delivered dose to the tumor, (2) measurement of tumor interstitial pressure, (3) in-situ generation of oxygen and (4) real-time tracking of tumor locations. This thesis describes our work in the design and implementation of four microdevices that help the radiation oncologist achieve a more effective delivery of treatment. The first chapter is devoted to cancer terminology, treatment methodology, and the importance of the aforementioned parameters in radiation therapy. After establishing the needs of developing each of these microdevices (designed specifically to address the abovementioned parameters) in the first chapter; design criteria, fabrication processes, and experimental results of each individual microdevice will be presented in the subsequent chapters. Finally, recommendations for future work will be discussed in the last chapter. Experimental methods, test procedures, and the output characteristics of each of these micro-devices will be presented. These include a self-biased solid state radiation sensor based on resistance modulation, a magnetic tracking system composed of four planar coils for excitation and a 2-D magnetoresistive magnetic sensor, an interstitial pressure sensor using a hermitic sealed capacitive pressure sensor with an incorporated Guyton chamber, and an ultrasonically powered in situ micro oxygen generator