Research On Optical CT Imaging Technology

Optical CT is a new technique of computed tomography. Based on Near-Infrared Spectroscopy (NIRS), Optical CT gains optical properties of the tissue by measurements of the NIR light fluence. Because of its advantages such as non-invasion, safety, economy, simplicity, and portability, Optical CT is a prospective medical imaging method in the future.Firstly, in this paper the theory of light propagation and diffusion is introduced. The software of FEMLAB based on finite element method is used to simulate the NIR light fluence in the tissue, which is just the forward problem of Optical CT. Then the inverse problem of Optical CT is treated as an optimization problem. Simulated Annealing Genetic Algorithm is applied to parameter optimization of diffusion equation through MATLAB tool. Experimental results show the feasibility of the method.Furthermore, based on the research of optical imaging method, the circuit of Optical CT is designed in this paper. The circuit is composed of two parts: one is to modulate optical source and the other is to process faint photoelectricity signals. A light emitting diode is used as optical source, which has single wavelength. PIN photodiode is used as the photodetector.Last, because the slight optical signal of Optical CT usually immerses in the noise signals, a phase-locked amplifier using correlation function is proposed in this paper. The phase-locked amplifier can acquire the slight optical signal immersing in the noise signals. The phase-locked amplifier is realized through LabVIEW. Also, the simulation of the phase-locked amplifier is studied. Experimental results show that this amplifier is useful in acquiring the slight optical signal immersing in the noise signals. The research all above provides a favorable basis for the further research in Optical CT.