Protoacoustics - Validation of proton range verification system for monitoring cancer treatments

Abstract:  An increasingly popular method for cancer treatment is proton radiation. Relative to conventional x-ray therapy, proton therapy is advantageous because protons have a limited range, called the Bragg peak (BP), which spares distal normal tissues. Despite its specificity, proton therapy carries some risk. For example, when there is an error in the range and the radiation under- or over-shoots, a drastically different dose is delivered. Due to this risk, a critical need exists to verify the proton range. Due to range uncertainty, proton treatment plans do not take full advantage of the proton's sparing capabilities. This becomes a clinically challenging issue, especially in deep seated tumors. For example, in the Central Nervous System (CNS) there are many organs at risk (OARs) such as the optic nerves, optic chiasm, brainstem, pituitary, and cochlea which abut the target site. Our application is focused on Protoacoustics, is the measurement of acoustic waves generated by clinical proton beams. Measurement of the arrival time of these kHz signals provides a simple and inexpensive method for real-time, in vivo monitoring of proton irradiation. Herein, we propose to develop a protoacoustic method for monitoring proton range in vivo by measuring the time-of-flight (TOF) of the pressure wave. We have discovered a novel role that applies this thermo-acoustic phenomenon to proton range-verification. The successful development of protoacoustic range-verification will provide greater confidence in proton range and consequently allowing smaller margins, improved sparing of healthy tissue and improved patient outcomes to build the foundation for Protoacoustics as a method for changing how proton therapy is monitored with improved targeting and decreased side effects.