UC Irvine

Acoustic waves are induced via the thermoacoustic effect in objects exposed to a pulsed beam of both ionizing and non-ionizing radiations. This phenomenon has interesting potential applications in both radiotherapy dosimetry and treatment guidance as well as low-dose radiological imaging. The objective of this thesis is to further investigate the clinical translations of acoustic waves elicited by ionizing radiations, specifically X-rays, and heavy particle beams, exemplified by proton beams, and demonstrate their potential applications in the forms of X-ray-induced acoustic computed tomography (XACT) for diagnostic radiology and proton-induced acoustic (PAI) imaging for radiotherapy dosimetry and treatment monitoring.In clinical radiological imaging, absorption-based CT imaging has been an invaluable tool in medical diagnosis. However, CT requires a large set of projection data and high radiation dose to achieve superior image quality. X-ray induced Acoustic Computer Tomography (XACT) is a novel imaging modality that combines the high contrast of X-ray and the detailed resolution of ultrasound to achieve fast imaging in three dimensions (3D). Comparing to traditional X-ray CT, A 3D volumetric image can be obtained from a single X-ray projection with XACT imaging. For the first time, we report the experimental demonstration of three-dimensional XACT reconstruction from a single X-ray projection angle. Proton-induced acoustic imaging (PAI) is a novel and low-cost radiotherapy monitoring method designed for both clinical and FLASH-rate proton beams. The study, conducted both in a water tank and on an anthropomorphic phantom, aims to demonstrate that Photoacoustic Imaging (PAI) technology is fully capable of three-dimensional in vivo imaging for proton dose deposition from clinical dose rate to FLASH-ready dose rate. The fidelity of the current PAI system iteration was rigorously assessed in terms of Bragg peak shape and range within an ideal medium—water. Further substantiating its clinical applicability, the human phantom study provided insights into how PAI would operate in a formal clinical treatment setting.