Evaluation of a Novel 3D Proton Beam Tracking System Utilizing Radar Imaging

Proton therapy, a form of cancer treatment that involves the use of high-energy protons to destroy cancerous tissue, currently lacks a standardized method for physical quality assurance of the proton beam’s location, instead relying fully on computational simulations. The present thesis reports, to the author’s knowledge, the first evidence for the use of radar waves as a physical quality assurance method for proton therapy. This method works due to absorption and refraction interactions between the radar waves and the free electrons generated by interactions between the protons and the patient’s tissues during proton therapy treatment (similar to a plasma). Previous research has shown that radar waves can be used to image plasmas, but this has generally been used for the purposes of aircraft stealth or visualization of plasma movement within the ionosphere. However, this phenomenon has not currently been used for a medical application. The purpose of this thesis is to provide preliminary data that supports the use of radar waves to track the proton beam as well as address some of the challenges associated with the design of such a system (e.g., antenna placement, antenna shielding, electrical noise). The data in this thesis indicates that the 6 GHz radar system used for testing purposes is capable of detecting the presence of what is likely a relatively low-frequency plasma source (similar free electron generation to the proton beam), although significant modifications (e.g., carrier frequency) must be made to the system to image a patient.