Intracranial hypertension is a serious threat to the health of neurosurgical patients. At present, there is a lack of a safe and effective technology to monitor intracranial pressure (ICP) accurately and nondestructively. In this paper, based on near infrared technology, the continuous nondestructive monitoring of ICP change caused by brain edema was studied. The rat brain edema models were constructed by lipopolysaccharide. The ICP monitor and the self-made near infrared tissue parameter measuring instrument were used to monitor the invasive intracranial pressure and the reduced scattering coe±cient of brain tissue during the brain edema development. The results showed that there was a negative correlation between the reduced scattering coe±cient (690nm and 834nm) and ICP, and then the mathematical model was established. The experimental results promoted the development of nondestructive ICP monitoring based on near infrared technology.

Near-infrared (NIR) light has been shown to produce a range of physiological effects in humans, however, there is still no agreement on whether and how a single parameter, like the flicker frequency of NIR light, affects the brain. An 810 nm NIR LED was used as the stimulator. Fifty subjects participated in this experiment. Forty subjects were randomly divided into four groups. Each group underwent a 30-minute NIR LED radiation with four different frequencies (i.e., 0 Hz, 5 Hz, 10Hz and 20 Hz, respectively) on the forehead. The remaining 10 subjects formed the control group, in which they underwent a 30-minute rest period without light radiation. EEG signals of all subjects during each test were recorded. Gravity frequency (GF), relative energy change, and sample entropy were analyzed. The experimental groups had larger GF values compared to the control group. Higher stimulation frequency would cause larger growth of GF (F = 14.75, P < 0.001). The amplitude of alpha waves relative energy increased, while theta waves decreased remarkably in the experimental groups (p < 0.02), and the extent of increase/decrease was larger at higher stimulation frequency, compared to that of the control. Sample entropy of electrodes in the frontal areas were much larger than those in other brain areas in the experimental groups (p < 0.001). Larger frequency of the NIR LED light would cause more distinct brain activities in the stimulated areas. It indicates that NIR LEDlightmay have a positive effect onmodulating brain activity.These resultsmay help improve the design of photobiomodulation treatments in the future.

考虑到激光间质热疗时激光从内置在组织中的光纤输出且光束为有限宽光束,建立了内插光纤的双层球体组织模型;基于蒙特卡罗法获得无限窄光束在组织内的吸收值,利用入射光强与格林函数进行卷积计算,获得有限宽光束的光传输方程;以高斯光束和平圆光束为例,分别对比分析了考虑与不考虑内插光纤时组织对有限宽光束吸收情况的变化。结果表明:组织对平圆光束的吸收值较小、对高斯光束的吸收值较大,内插光纤对组织吸收平圆光束的影响较小,而对光子出射中心附近组织吸收高斯光束的影响较大。因此,采用高斯光束进行激光间质热疗时应考虑内插光纤对组织吸收光能的影响。所提模型更加接近激光间质热疗的实际情况,对准确预估激光间质热疗的热毁损范围具有重要的意义。

考虑到肿瘤的形状特征以及激光间质热疗时激光的传输方式为内置光源,首先建立了内插光纤的双层球体生物组织模型,然后假设光子从球体中心发射,建立了光子在组织内、球体边界及内插光纤表面的传输方式,最后采用Visual Studio软件编程,基于蒙特卡罗法对光在该组织模型中的传输进行仿真。仿真结果表明:光纤主要对光子出射端面附近的光子的运动产生影响;位于光子出射面下方的组织对光子能量的吸收大于出射面上方组织对光子能量的吸收;内层球体的半径越小,内边界的吸收值越大。与传统的蒙特卡罗方法相比,所建模型更接近于激光间质热疗的实际情况,对后续准确预估激光间质热疗的热毁损范围具有重要的实际意义。

Accurate placement of pedicle screw (PS) is crucial in spinal surgery. Developing new real-time intra-operative monitoring and navigation methods is an important direction of clinical application research. In this paper, we studied the spectrum along the fixation trajectory of PS in frequency domain to tackle the accuracy problem. Fresh porcine vertebrae, bovine vertebrae and ovine vertebrae were measured with the near-infrared spectrum (NIR) device to obtain the reflected spectrum from the vertebrae. Along the fixation trajectory of PS, average energy from different groups was calculated and used for identifying different tissues and compared to achieve the optimal recognition factor. Compared with the time domain approach, the frequency domain method could divide the spectra measured at different tissue points into different groups more stably and accurately, which could serve as a new method to assist the PS insertion. The results gained from this study are significant to the development of hi-tech medical instruments with independent intellectual property rights.

Laser speckle contrast imaging (LSCI) is an optical imaging method, which can monitor microvascular flow variation directly without addition of any ectogenous dye. All the existing laser speckle contrast analysis (LASCA) methods are a combination of spatial and temporal statistics. In this study, we have proposed a new method, Gaussian kernel laser speckle contrast analysis (gLASCA), which processes the raw images primarily with the Gaussian kernel operator along the spatial direction of blood flow. We explored the properties of gLASCA in the simulation and animal cerebral ischemia perfusion model. Compared with the other existing speckle processing methods based on spatial, temporal, spatial-temporal or anisotropic linear structure; the present gLASCA method has a high spatial-temporal resolution to respond the change of velocity especially in microvasculature. Besides, the gLASCA method obtains approximately 10.2% and 7.1% higher contrast-to-noise ratio (CNR) over the anisotropic linear method (aLASCA) in the simulation and experiment models. For these advantages, gLASCA could be a better method for local microvascular laser speckle imaging in terms of cerebral ischemia reperfusion, spreading depression and brain injury diseases.

采用反向并联肖特基二极管对设计了一种330 GHz二次谐波混频器。混频器电路采用微带结构，使用波导-微带探针耦合的形式进行过渡；采用50 μm厚的石英作为基板，有效减小了电路体积；采用HFSS和ADS对电路进行仿真和谐波平衡仿真。仿真结果显示，混频器在310~350 GHz范围内的变频损耗优于9.5 dB，所需本振(LO)功率为3 dBm，有效降低了对本振的要求。

以波长为720 nm处的散射光强I720为评估光学参数，探讨了激光热毁损过程中用远中心处双点光学参数实时评估近中心处热毁损效果的可行性。首先，对离体猪肝进行激光热毁损实验，实时采集距离毁损中心4，8，12 mm处的I720，当8 mm处的I720上升至初值的6倍时停止加热，共进行20组实验（A组），构建加热时间、8 mm和12 mm处I720上升倍数与4 mm处I720上升倍数的数学模型；然后，分别以4 mm处I720上升至初值的3、4、5、6倍为停止加热的条件，重复上述热毁损实验和实时数据采集，每种条件下各进行10组实验，共40组（B组）；最后，对B组实验的样本进行切片分析，建立I720上升倍数与毁损效果的对应关系。实验表明，利用加热时间、8 mm和12 mm处I720上升倍数估算4 mm处I720上升倍数的准确率可达90%以上。可用远离加热中心的双点光学参数实时评估近中心处激光热毁损效果。

Because the brain edema has a crucial impact on morbidity and mortality, it is important to develop a noninvasive method to monitor the process of the brain edema effectively. When the brain edema occurs, the optical properties of the brain will change. The goal of this study is to access the feasibility and reliability of using noninvasive near-infrared spectroscopy (NIRS) monitoring method to measure the brain edema. Specifically, three models, including the water content changes in the cerebrospinal fluid (CSF), gray matter and white matter, were explored. Moreover, these models were numerically simulated by the Monte Carlo studies. Then, the phantom experiments were performed to investigate the light intensity which was measured at different detecting radius on the tissue surface. The results indicated that the light intensity correlated well with the conditions of the brain edema and the detecting radius. Briefly, at the detecting radius of 3.0 cm and 4.0 cm, the light intensity has a high response to the change of tissue parameters and optical properties. Thus, it is possible to monitor the brain edema noninvasively by NIRS method and the light intensity is a reliable and simple parameter to assess the brain edema.

During neurosurgery, an optical probe has been used to guide the micro-electrode, which is punc-tured into the globus pallidus (GP) to create a lesion that can relieve the cardinal symptoms. Accurate target localization is the key factor to affect the treatment. However, considering the scattering nature of the tissue, the “look ahead distance (LAD)" of optical probe makes the boundary between the different tissues blurred and difficult to be distinguished, which is defined as artifact. Thus, it is highly desirable to reduce the artifact caused by LAD. In this paper, a real-time algorithm based on precise threshold was proposed to eliminate the artifact. The value of the threshold was determined by the maximum error of the measurement system during the calibration procession automatically. Then, the measured data was processed sequentially only based on the threshold and the former data. Moreover, 100 m double-fiber probe and two-layer and multi-layer phantom models were utilized to validate the precision of the algorithm. The error of the algorithm is one puncture step, which was proved in the theory and experiment. It was concluded that the present method could reduce the artifact caused by LAD and make the real boundary sharper and less blurred in real-time. It might be potentially used for the neurosurgery navigation.