Radiation-Induced Acoustic Imaging System Development and Applications

Abstract

This thesis reports the development of three different radiation induced acoustic imaging systems excited by a pulsed laser, X-ray, and electric field respectively. Firstly, a laser induced photoacoustic imaging system for non-destructive testing (pNDT) is presented in Chapter I. The pNDT is comprised of three major components: picosecond pulsed laser based ultrasonic actuator, ultrasound receiver, data processing and computing subsystem. A CFRP composted was scanned and both the micro-scale and macro-scale damage are detected and localized with spatial resolution of 100 µm. Secondly, an X-ray-induced acoustic tomography (XACT) system was developed for bone imaging in Chapter II. A 500 KHz ultrasound transducer was used to obtain a 3D image of a chicken bone placed underneath the -ray source. The first XACT biological bone sample was linearly scanned with 12-posiiton increments. The image was then obtained with a back-projection reconstruction algorithm. The chicken bone was successfully reconstructed, demonstrating the potentials of XACT systems in bone density in vivo imaging. Thirdly, a new imaging modality, electroacoustic tomography (EAT), was designed for electrical therapy monitoring. The acoustic signals generated by high-voltage pulsing electrical fields during electrical therapies were detected and analyzed. The optimal parameters for effective EA signal generation were found. The results demonstrated the potentials of the pNDT system in ultra-high resolution CFRP NDT, the XACT system in fast 3D bone imaging, and the EAT system in real-time electric therapy monitoring.