Focused Photoacoustic Imaging Analysis With Transducers In Different Frequencies And Its Application For Thyroid3D Imaging

In recent years, a novel medical imaging technology which has the advantages of noninvasive and secure detection, high resolution, excellent contrast as well as deep penetration imaging, has emerged. It is the photoacoustic imaging (PAI) that is based on photoacoustic (PA) effect. The structure and physiological information of human tissue can be obtained through detecting the outgoing ultrasound coming from the chromophores inside tissue excited by a pulsed laser light. PAI has provided a new imaging modality for clinical medical imaging, which has some unique advantages compared with other imaging techniques. Therefore, PAI is expected to be a highly promising medical imaging technology. In this thesis, based on a focused PA imaging system, we have mapped the light energy distribution inside mimic lesions, analyzed photoacoustic imagings with different frequencies and obtained3D PA imaging of human thyroid tissue. The main contents of this thesis are as follows:1. The mainstream of medical imaging technology and the development of PAI both in the domestic and international research are reviewed. Furthermore, the main problems in current PAI development and the significance of this research are discussed.2. The theoretical principles of PAI are described, including the mechanism of PA signal generation and the establishment of PA wave equation.3. Focused PA system and research approaches in our experiment are comprehensively introduced.4. Measurements of the light energy distribution inside mimic lesions using focused PA imaging are carried out, which can further reveal the optical properties and physiological features of lesions in the tissue. This method has provided a new approach for early cancer diagnosis.5. The features and differences of different frequency photoacoustic imaging are analyzed. Then, focused PA imaging technique is used to diagnose human gland noninvasively. Moreover,3D human thyroid PA imaging is realized, which is expected to be a potential clinical tool for increasing diagnostic accuracy and providing more effective technical support and solutions for thyroid treatment.