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The characteristic identification factor of the vertebra at different positions was studied by spectroscopic technology.The spectral measurement system consists of computer,the integrated hand drill with dual-fiber probe(each fiber′s core diameter is 200 μm and the distance between the center of two fibers is 0.5 mm),halogen light source(wavelength is from 360 nm to 2 000 nm) and fiber optic spectrometer(detection wavelength: 200～1 100 nm).The diffuse reflectance spectrum and the reduced scattering coefficient of biological tissue could be obtained at the same time.Pig′s vertebra was chosen as experimental subject to measure the diffuse reflectance spectrum and scattering coefficient of different bone tissue on pedicle screw placement pathway.The characteristic identification factor was defined by analyzing the peak values,the size of the area and the slope of the spectrum in specific wavelength.We find that different bone tissue′s spectrums show different characteristics.The change of the peak values was 1.77 and the change of the area values was 2.13 times higher than that of scattering coefficient,respectively.At the range of 495 nm to 505 nm,the slope of spectrum of cortical bone and cancellous bone was positive.At the range of 520～535 nm,the slope of spectrum of cortical bone was positive,and the slope of cancellous bone was negative.It can be concluded that the peak value,the area and the slope obtained by analysis of spectrum′s characteristics could distinguish the difference between cortical bone and cancellous bone.

In the research of mouse traumatic brain edema,the near infrared spectroscopy effective detection depth is not clear.Aiming at that problem,Monte Carlo method was used to simulate the photon distribution in biological tissue.The photon′s effective detection depth was calculated from the photon distribution.The multi-layer model of mouse brain was obtained by the segmentation of MRI.The advanced value segmentation,narrowband level set were used to segment the scalp,the skull,cerebrospinal fluid,gray and white matter from the whole brain MRI.This segmentation method does not depend on templates.The tMCimg software,which is used to simulate the photons′ optical distribution in complex tissues,was modified to record the photons′ position and the photons′ energy used in the calculation of the effective detection depth.The effective detection depth was discussed with the different center distance of source and detector and radius of source.Effective detection depth in tissue is less than or equal to half of the distance source and detector and it increases with the radius of the source.The mouse brain edema model was built to verify the simulation.The result is important to the design of source and detector probe and the detection of the edema region.

A noninvasive monitoring method for brain edema based on near infrared photoelectric detection technology is proposed.The measurement principles and system composition of the monitoring instrument are studied.The light source of the instrument is 760 nm and 850 nm dual-wavelength LED,which is driven by constant current source module.The light signal,scattered from the tissue,is detected by OPT101.Then the signal is processed by phase-locked amplifier and filter circuit.The filtered data are sampled by data acquisition card and processed in the LabVIEW environment in computer.The proposed system can monitor the changes in the brain of hemoglobin on real time.The system is used to monitor the changes of light intensity and blood oxygen content of the model of brain edema in mouse.The relationship between the changes of light intensity and oxygen parameters and brain edema is studied.The experimental results show that the near infrared photoelectric detection technology can be used as the noninvasive monitoring method for brain edema.