Development Of Rotary Breast Diffusion Optical Tomography Equipment

Breast cancer is a type of malignant tumor with the highest incidence among women.Early diagnosis and treatment is very important for improving the survival rate of breast cancer patients.At present,the imaging detection methods widely used in clinical,such as mammography,breast MRI,are limited by their technical characteristics,there are defects such as high price,poor safety,etc.,making such detection methods unsuitable for breast cancer early screening work.Diffusion optical tomography(DOT),which is a new type of optical imaging technology that can provide highly specific functional imaging of tissues,and has the advantages of non-invasive,non-radiative,low cost and so on.In addition,because breast tissue is rich in fat and has a special shape,DOT technology has great advantages and potential in the early detection of breast cancer.This thesis focuses on the early detection of breast cancer,and develops a rotating multi-wavelength DOT imaging system for the problems of the traditional DOT system,such as the complex structure and poor channel consistency.The system supports two imaging modes,continuous wave and frequency domain,without optical fiber for optical transmission.Compared with traditional systems,it simplifies the system structure,reduces optical loss during transmission,improves channel consistency,and reduces system cost.The main work and innovations of this thesis are summarized as follows:1.A rotating DOT system design scheme is proposed.The rationality of the scheme,the feasibility of frequency domain imaging and the problems related to system design were studied.The feasibility of the scheme is verified,and it provides a reference basis for the subsequent system design.Through simulation comparison experiments,it is proved that the rotating system structure has the same imaging quality as the conventional system structure.Through simulation comparison experiments,it is proved that the rotating system structure and the conventional system structure have equivalent imaging quality.Through frequency domain simulation experiments,the feasibility of frequency domain imaging at 20-40MHz is verified.By designing simulation experiments with different parameters,the effects of different detector spacing and data collection density on imaging results were studied,and a reasonable range of detector spacing and data collection density was determined.Provide theoretical support for system design.2.Designed and built a rotating multi-wavelength DOT imaging system.Through the application of emerging optical devices and special circuit and system structure design,the system is defibrated,reducing the complexity of the system,reducing the optical loss during the transmission process,through the rotary structure design,the number of system light sources is reduced,The channel consistency is improved and the system cost is reduced;by introducing multiple light source wavelengths,the separation of different absorbing substances in the heterogeneous body can be achieved.The excitation module is designed based on low-power laser diodes,the detection module is designed based on SiPM and flexible PCB,the system is rotated by an electric rotating table,and the performance test of the core module of the system is carried out.In addition,the system’s supporting control software was developed to realize the switching control of the detection,the rotation control of the system and the data collection control.3.A variety of data correction and processing schemes are proposed to achieve the optimization of reconstruction quality.The phantom imaging experiments in continuous wave and frequency domain are designed to verify the effectiveness of the correction scheme and determine the imaging performance of the system.Aiming at the data error problem that affects the imaging quality caused by the system’s errors and other uncontrollable factors,a data correction scheme is designed:a normalized correction method is proposed,and by combining the conventional Bonn ratio correction method and the data processing method of channel elimination,the correction of the system data is-realized,and the imaging quality is effectively improved.Through continuous wave and frequency domain phantom experiments,the feasibility of the correction scheme is confirmed.The reconstruction results show that the system positioning error is less than 2mm,which can achieve accurate positioning of the heterogeneous body and achieve the design goals.