Three-dimensional Photoacoustic Tomography For The Distribution Of Drug Delivery In Vitro

Photoacoustic imaging(PAI)is a new composite biomedical imaging technology which combines optical and acoustic characteristics.It not only inherits the high optical tissue contrast of traditional optical imaging,and can realize the specific functional imaging of biological tissue,but also because it detects ultrasonic signals excited by pulsed light,compared with pure optical microscopic imaging,The imaging mode breaks through the limit of optical diffraction and has a larger imaging depth.The spatial resolution and image characteristics of photoacoustic imaging are related to the scanning mode of the system,the frequency response of ultrasonic probe,numerical aperture and other factors.it can reach the order of millimeter to micron,and different system design schemes can be adopted according to different purposes.Photoacoustic imaging is widely used in the fields of early nondestructive testing of cancer,research and development of related drugs,and therapeutic testing.By combining with targeted contrast media,photoacoustic imaging can perform specific functional imaging with high resolution,high imaging depth and high sensitivity to the distribution of targeted contrast agents in tumors,and to study the formation of tumors at the molecular level.It is of great scientific significance to investigate the mechanism and therapeutic effect of related drugs in the treatment of tumor.1.General situation,principle and classification of photoacoustic imaging.In this paper,the advantages of photoacoustic imaging compared with other commonly used medical imaging methods are described,and the research progress of photoacoustic imaging as a new imaging method in tumor pathology and treatment monitoring is reviewed.However,since the photoacoustic signal of the blood of the tumor and surrounding tissue is often submerged by the photoacoustic signal targeting the contrast agent,even if the appropriate wavelength is selected,in the process of photoacoustic imaging of the body,in addition,the photoacoustic signal of the blood of the tumor and the surrounding tissue is often submerged by the photoacoustic signal of the tumor and the surrounding tissue.The back detection mode used in vivo photoacoustic imaging is not conducive to the detection of tumor tissue from more angles,so it can not effectively evaluate the distribution of contrast agents in the tumor.For this reason,the method of photoacoustic tomography is proposed to detect the distribution of targeted contrast media in tumor in vitro.In this paper,a cylindrical scanning three-dimensional photoacoustic tomography(PAT)system based on linefocusing probe was built,the performance of the system was tested,and the distribution of contrast medium in mouse tumor in vitro was studied.The main contents include the following aspects:1.General situation,principle and classification of photoacoustic imaging.This paper describes the advantages of photoacoustic imaging compared with several other commonly used medical imaging methods,and summarizes the research progress of photoacoustic imaging as a new imaging method in tumor pathology and treatment monitoring.2.The principle of photoacoustic generation and propagation is discussed.In addition,two different reconstruction algorithms of photoacoustic tomography are presented,and their advantages and disadvantages are compared.3.Study on two-dimensional photoacoustic tomography.In this paper,the photoacoustic tomography system used in this paper is described in detail,and two-dimensional photoacoustic tomography of imitating body scanning data is carried out by using this system with two different algorithms,and the results of image reconstruction are demonstrated and analyzed.It lays a good experimental foundation for three-dimensional imaging.4.Three-dimensional photoacoustic tomography of mouse tumor in vitro.In this paper,a three-dimensional photoacoustic tomography system based on linear focused ultrasonic transducer is built.The method of three-dimensional tomography is introduced in detail,and the influence of the performance parameters of the ultrasonic transducer on the final resolution of the system is given.Two different scanning methods are introduced and their advantages and disadvantages are compared.After that,the three-dimensional photoacoustic tomography system built in this experiment is used to test the hair imitation.The photoacoustic three-dimensional tomography of mouse tumor containing ICG was performed with this system.Through the analysis of the scanning experimental results,the possibility of the application of the photoacoustic imaging system in the detection of tumor drug distribution was evaluated.