Photoacoustic And Ultrasound Dual-Modality Imaging System And Its Preliminary Application For Gastric Cancer

Photoacoustic(PA)imaging is a new medical imaging technology,with high contrast of optical imaging and high resolution of ultrasound imaging.It has been widely used in tumor detection,brain imaging,blood flow measurement and other aspects.Based on this background,this thesis focuses on the problem of PA imaging in the early detection of gastric cancer,and conducts a preliminary study including the light absorption and distribution of gastric tissue,the construction of imaging system,and the imitation experiment.This thesis mainly carried out the following aspects of work:Firstly,the current mainstream medical imaging technologies is introduced.The progress of the research on PA imaging at domestic and abroad is summarized.Afterwards,the research background of this topic and the significance of this topic are explained.Secondly,some theories of photoacoustic imaging technology are introduced,including the generation conditions of photoacoustic effect,the basic principle of photoacoustic imaging,and the derivation process of the photoacoustic wave equation.Then introduced the imaging system built in the laboratory and measured the resolution of the system.Thirdly,a comparative analysis of ultrasound imaging and PA imaging is made.The contrast analysis is mainly from three aspects:the imaging principle,signal detection and the reconstruction algorithm.Fourthly,the basic principle of Monte Carlo simulation is introduced.The optical model distribution of gastric wall tissue is constructed.The transmission distribution of light in gastric wall tissue and gastric tumor is simulated.The light energy distribution in the stomach wall and the stomach tissue was obtained preliminary,and the influence of the change of the optical parameters on the light energy distribution was obtained.Finally,the imaging experiments of the isolated pig stomach tissues were carried out,and the ultrasonic images and the PA images of the samples were obtained.And the experiments have proved that PA imaging technology is feasible for the detection of gastric cancer.Although there are some limitations of the experiment,but also provide a certain basis for the follow-up researches.