Development Of Compact Multi-wavelength Diffusie Optical Breast Imaging Equipment Based On SiPM

The latest cancer statistics show that breast cancer is the highest incidence of malignant tumors in women,and has become the biggest threat to women's life and health.At present,clinical breast cancer detection methods,such as mammography and ultrasound imaging,have some shortcomings in safety,specificity and comfort.Diffuse optical tomography(DOT),which is based on the difference of optical parameters between cancerous and normal tissues,has higher sensitivity and specificity for breast tumors.It can provide abundant functional information and has good application prospects in early breast cancer detection and evaluation of neoadjuvant chemotherapy.However,the existing DOT imaging system are much too complex in structure and expensive.The objective of this study is to develop a compact multi-wavelength DOT imaging system based on silicon photomultipliers(Si PM).Compared with the traditional imaging system,this system reduces the complexity of the structure and the cost.This research involves hardware design,system building,program development and performance testing.The work that been done in this thesis are as follows:1.The feasibility study of diffuse optic detection technology based on SIPM is carried out.Traditional DOT systems usually use photomultiplier tubes(PMTs)as detectors,and use optical fiber to couple the receiving optical signal,which results in complex system structure and high cost,and limited the application of DOT in clinic.Aim at this problem,a new photoelectric detector Si PM is used instead of PMT,which can effectively reduce the complexity and cost of the system structure.In order to verify the feasibility of using Si PM for diffuse optic detection,the relationship between received signal strength and optical transmission distance in continuous wave mode is tested by using the Si PM working circuit.In frequency domain,the relationship between amplitude and phase of received signal and optical transmission distance is obtained.The experimental results are in good agreement with the theoretical results obtained from the analytical solution of the diffusion equation,which indicates that it is feasible to use Si PM for diffuse optic detection.2.Design and development of multi-wavelength DOT imaging equipment based on Si PM.For the hardware,32 three-wavelength LED is used as excitation and 32 Si PM as detection.A set of three-wavelength breast DOT imaging equipment with continuous wave mode is developed.The working circuit of each module is designed and manufactured.For the software,a set of software is developed to control the operation of the equipment,which?realizes the digital control switching of the excitation light source channels and 32-channel parallel acquisition.The performance of each part is tested to ensure that its performance meets the requirements of the equipment.Finally,the system integration is completed.The total time of data acquisition in 32 channels for three wavelengths is 53 seconds,and the signal-to-noise ratio is more than 60 d B.3.Phantom experiments are carried out to verify the imaging performance of the device.The method of differential measurement is used to correct the data and eliminate the system error.In order to test the performance of the equipment,this thesis designs several phantoms with different number and depth of heterogeneous,and carries out imaging experiments.The results show that the equipment can locate the heterogeneous and get the reconstructed image.The locating error is not more than 2 mm and the effective imaging depth is not less than 38.8 mm.