The photonic NanoPhone, an all-optical array receiver containing several hundreds of small and sensitive yet inexpensive acoustic sensors, will be beneficial to at least two important medical applications. In proton therapy, the NanoPhone will enable the monitoring and adjustment of both the trajectory and the strength of the proton beam during treatment. In intravascular ultrasound imaging, it will afford a much higher lateral resolution than conventional piezo-based sensors do. Moreover, since the NanoPhone will be insensitive to electromagnetic interference (EMI), it will also be suitable for use in an MRI environment. This research project will focus primarily on its application in proton therapy.