Construction And Performance Test Of Diffusion Optical Imaging System

Diffuse optical tomography(diffuse optical tomography,DOT)is specific,dynamic,and sensitive to changes in tissue function.It also has the advantages of safety,reliability,and low cost.Therefore,near-infrared diffusion optical tomography has a wide range of application potential and research value.At present,the main applications of DOT technology are brain function imaging and breast imaging.For breast imaging,if the tissue becomes cancerous,it will have obvious vascularization characteristics and absorb light more strongly than normal tissue.Therefore,DOT technology can be used to visualize endogenous substances such as hemoglobin,water,and lipids in the mammary gland to obtain the differences in physiological parameters between tumor tissues and normal tissues.In view of the advantages of DOT imaging,this paper designs and builds a DOT imaging prototype system to further study DOT imaging and apply this technique to breast imaging.Based on this,it mainly completed the following tasks:Designed and developed a DOT imaging system,including hardware system implementation and software system development.The hardware system mainly includes three parts,namely the excitation module,the transmission module and the detection module.The realization of the hardware system includes the overall system structure design and hardware module selection.The software system mainly includes optical switch control program and data acquisition program.In order to use the high dynamic range of the PMT module in the system design process,an automatic gain control method of the PMT module is proposed,so that the PMT module can use different gains according to different detection positions,thereby improving the detection efficiency of the PMT module.Finally,the feasibility and accuracy of the method were verified by using the imitative experiment.In order to ensure the stable and efficient operation of the system,the system was tested for performance,including performance testing of each module device and overall system performance testing.The test of each module device mainly tests the working performance and the best working range of each device.The overall system performance test mainly tests the linearity and stability of the system.In order to eliminate systematic errors,two methods of normalization and differential measurement were used.The experiments of the two methods are verified by using the imitative experiment.The experimental results show that the differential measurement method is superior to the normalized measurement method.Test the influence of low-frequency sinusoidal signal modulation on signal-to-noise ratio and image reconstruction effect,and carry out relevant phantom experiments.Experimental results show that the introduction of low-frequency sine modulation signal can improve the signal-to-noise ratio and the quality of the reconstructed images.