DIRS Laboratory 76-3215
October 29, 2018 at 3:00am
ZICHAO HAN
Ph.D. Thesis Defense
Abstract: 

Prostate cancer is currently the second leading cause of cancer death in American men. Diagnosis of the disease is based on persisting elevated prostate-specific antigen (PSA) levels and suspicious lesion felt on digital rectal examination (DRE), prompting transrectal ultrasound (TRUS) imaging guided biopsy. This method, however, has long been criticized for its poor sensitivity in detecting cancerous lesions, leading to the fact that these biopsies generally are not targeted but systematic multi-core in nature that try to sample the entire gland. The thesis presents a new modality that, in combination of ultrasound (US) imaging with multi-wavelength photoacoustic (PA) imaging, improves the physician’s ability to locate the suspicious cancerous regions during biopsy.

Here, building further on the innovation of an acoustic lens based focusing technology for fast PA imaging, a novel concept with the use of a polyvinylidene fluoride (PVDF) film that incorporates US imaging into our existing PA imaging probe is presented. The method takes advantage of the lens based PA signal focusing technology, while simultaneously incorporates US imaging modality without interfering with the current PA imaging system design and structure. Simulation and experimental support on tissue equivalent phantoms is provided in detail. The thesis also elaborates on the signal-to-noise ratio (SNR) improvement of the US imaging component by driving the film with frequency modulated (FM) signals. In addition, a custom-designed US simulation software that is developed to explore and evaluate various system design options is discussed. The dual modality transrectal probe is only intended as a first step. The long term goal of the study is to facilitate locating the cancer region in-vivo with PA imaging, transfer it to co-registered US image, and use the real-time US imaging for needle guidance during biopsy.