近红外反射光谱研究光透明剂渗透特性对胃组织光学透明的影响

为了解高渗溶液渗透特性对生物组织的光学透明进程的影响，探索光透明剂的安全有效浓度，用近红外反射光谱和相干光断层成像(OCT)研究了两种光透明剂丙三醇(甘油)和二甲亚砜(DMSO)以及二者的混合溶液[体积分数为80％的甘油水溶液，50％的DMSO水溶液，50％的甘油 20％的DMSO水溶液(GD1)和50％的甘油 30％的DMSO水溶液(GD2)]对胃黏膜组织的光学透明作用。结果表明，这四种溶液都能显著增强近红外光在胃黏膜组织中的穿透能力，光学透明的能力由低到高依次为体积分数为50％的DMSO，80％的甘油，GD1和GD2。发现生物组织光透明进程的快慢和效果与光透明剂的渗透所导致的组织的失水速率和程度成正比。     

光清透剂对激光疗效影响的实验研究

为了探究光清透剂在减少皮肤组织散射,提高到达靶组织激光能量方面的作用,利用皮肤仿体定量研究了可见-近红外波长下甘油的光清透效果。搭建了葡萄酒色斑激光治疗的体外模拟实验系统,研究光清透效果与多脉冲Nd∶YAG激光作用下血液凝结特性之间的定量关系。结果表明,0.5mL无水甘油涂抹在仿体表面10min后,在波长1064nm处仿体的漫反射率降低36.69%,透射率增加38.73%。将无水甘油涂抹在仿体表面4min后,仿体下毛细血管中血液凝结所需激光脉冲数目减少了25%。作用10min后,所需激光脉冲数目并未进一步减少,但血液凝结面积与4min时相比增加了34.1%。这说明甘油能有效提高病变血管对激光能量的吸收,改善葡萄酒色斑的疗效。     

整体器官的光透明成像方法综述

现代光学成像技术与荧光标记技术不断发展,为高分辨地获取生物组织三维结构信息提供了重要的工具。然而,大多数生物组织具有不透明特性,限制了光在组织中的穿透深度,进而限制了光学成像技术在大组织或整体器官成像中的应用。近年兴起的组织光透明技术通过多种物理、化学手段降低组织对光的衰减,增加光穿透深度,从而提高光学成像的成像深度与成像质量,为整体组织器官的三维成像提供了全新的思路。本文从离体组织光透明方法、大组织器官标记方法、三维整体成像技术三个方面,对整体器官的光透明成像方法进行综述。     

超声波和丙三醇对皮肤光透明性的影响

采用光学相干层析成像技术(OCT)系统对分别经低频超声波,80%甘油和二者同时作用于皮肤组织进行实时监测而获取图像,并运用计算机软件对皮下深度为0.012 mm处及表皮层OCT图像一维的灰度值进行皮肤组织的光学透明性的定量分析.结果表明.低频超声波和80%甘油相结合将有利于在短时间内改善生物组织的成像深度,两者在组织的光透明性方面具有协同效应.     

光动力作用效果的剂量学描述探讨

讨论肿瘤光动力治疗中光敏药物剂量、光剂量的描述和测量,利用光动力损伤剂量把光动力作用中光敏药物剂量、光剂量和组织氧浓度三者联系起来,分析说明定量讨论光动力作用效果的可行性和重要性,建立光动力作用效果与光敏药物剂量、光剂量、氧浓度以及组织光学参数的关联,所得到的定量关系对设计合理的光动力治疗方案有借鉴作用。     

仅有光开关还不足以形成透明网络

采用透明网络结构决不仅仅需要一套良好的光开关技术,网络部件及系统的设计人员还必须考虑透明网络动态光学路径的具体设计。     

基于空间频域成像的人体皮肤组织光学和生理参数的提取

人体皮肤组织的光学参数和生理参数对于众多疾病的检测与监测具有重要意义,基于空间频域成像技术提取光学、生理参数具有潜在的临床应用价值。空间频域成像技术需要至少在两个波长下提取氧合血红蛋白和脱氧血红蛋白浓度;在反演人体皮肤组织中的氧合血红蛋白和脱氧血红蛋白浓度时,皮肤中的黑色素会增加结果的不确定度。本课题组搭建了一套空间频域成像系统,在反演人体皮肤组织生理参数的算法中引入最小二乘法和最小误差准则,以解决不确定度问题。实验结果表明：该系统获得的梯度漫反射板的测量值与准确值线性相关,且获取的组织仿体的吸收系数与直接测量法获取的吸收系数的偏差在0.3%～9.6%之间,验证了该系统测量光学参数的有效性。通过对不同黑色素含量的组织仿体进行测量后发现,系统的测量浓度与配制浓度之间显著相关。血液仿体实验和动脉闭塞实验结果表明,系统测量的氧合血红蛋白、脱氧血红蛋白、总血红蛋白浓度以及血氧饱和度随时间变化的趋势符合血液实验变化趋势和闭塞条件的变化趋势,进一步验证了空间频域成像算法提取生理参数的准确性。在体和离体实验结果均说明空间频域成像方法可以用于组织体中血氧饱和度的测量,为实现相关疾病的无创、快速检测提供...     

P(VDF/TrFE)聚合物薄膜光波导的实验研究

采用棱镜耦合法和偏振反射技术研究了Ｐ（ＶＤＦ／ＴｒＦＥ）聚合物薄膜光波导特性。配制适当重量比浓度的Ｐ（ＶＤＦ／ＴｒＦＥ）溶液,通过提高极化时的温度,可制成均匀透明的极化聚合物薄膜平面波导。Ｐ（ＶＤＦ／ＴｒＦＥ）成膜后薄膜内部的晶界与晶粒对于其光学性质的影响可以获得较大改善。样品用旋涂法制备。研究了制备工艺对光学特性的影响。     

光-电-光转换技术是光学网络的竞争技术

据康宁公司的M.Krol说：光学网络的市场焦点已从扩容转向费效比合算的网络经营。大约40%的光学网络开销花费在无必要的光-电-光（OEO）转换上。2001年6月由美国光学学会在加州蒙特里举行的关于光交叉连接的联合讨论会上，Krol和其他发言人均认为，在现有技术的基础上，该问题的解决在于将网络通信量分成无光-电-光的传输层面和与光-电-光有关的服务层面（见图）。分岐在于如何做，各种解决办法往往跟随各装备供应商选定的元件技术路线。据Calient网络的J. Bowers说，在典型的美国光学网络节点，大约80%的通信量能用透明的光学转换传输，…     

金纳米棒的制备及其在光声成像中的应用

该文制备了巯基聚乙二醇（PEG）修饰的金纳米棒,该纳米材料在近红外区具有良好的光吸收特性,具备作为优良光声造影剂的潜质。该文通过透射电子显微镜（TEM）、紫外 可见（UV VIS）吸收光谱等测量手段对金纳米棒进行了形貌、结构、基本光学性能及光声成像效果等表征。实验结果表明,随着材料浓度的增加,体外光声信号的响应近似呈线性增长;经由PEG修饰,金纳米棒的生物相容性得到提高;PEG修饰后的金纳米棒对小鼠大脑皮层血管的成像效果得到提升。结果表明,PEG修饰的金纳米棒材料,在光声成像造影领域具有巨大的应用前景。     

Feasibility of sonophoretic delivery for effective skin optical clearing

In an attempt to find a noninvasive way to improve the efficacy of skin optical clearing with topical application of optical clearing agents (OCA), we exploited the effect of ultrasound on optical clearing of intact skin in vitro Changes in optical transmittance and diffuse reflectance of the porcine skin under different treatment procedures were measured by a UV/Vis/NIR spectrophotometer. Clearing capability of glycerol or propylene glycol was much improved with the simultaneous application of ultrasound with a frequency of 1 MHz and a power of 0.75 W over a 3-cm probe. Light transmittance at 470 and 1276 nm increased by 112%-128% and 54%-65%, respectively. The most significant effect was seen where skin was treated with the combination of ultrasound and the chemical enhancer azone, resulting in a 2.3-fold increase of optical clearing at 1276 nm. We demonstrate the feasibility of using sonophoretic delivery methods to improve skin optical clearing with topical application of OCA.     

Influence of glycerol on the mechanical reversibility and thermal damage susceptibility of collagenous tissues

Clinical procedures wherein supraphysiologic temperatures must be achieved in deep layers of tissue via light are often compromised by optical scattering and absorption. Optical clearing of tissue superficial to the target improves the efficacy of such procedures. Glycerol is an attractive chemical agent for achieving dramatic reductions in tissue turbidity, but its net effects on healthy tissue are not fully understood. In this paper, we investigate possible alterations of biaxial mechanical properties in a model collagenous tissue, bovine epicardium, induced by glycerol. Furthermore, we examine the effects of glycerol on the biaxial thermomechanical properties of epicardium constrained at near-physiologic length. It is seen that mechanical changes induced by glycerol are fully reversed upon rehydration in normal saline. Moreover, glycerol protects cleared tissue by increasing its thermal stability and minimizing thermal alterations of mechanical properties.     

不同结构生物组织光透明作用比较

为了了解生物组织不同结构对光透明进程的影响,利用光相干断层成像术(OCT)和近红外光谱(NIR)对肌肉组织(猪骨骼肌)和上皮组织(猪胃黏膜)经丙三醇处理后的光透明效果进行了比较研究。结果表明,这两种组织的光相干断层成像术成像深度和内层次结构的成像对比度均得到改善;肌肉组织和胃黏膜组织的光透射率分别增加了21%和16%,而漫反射率分别降低了33%和21%;这两种结构组织的光透明效果(肌肉组织较好)和进程(肌肉组织较快)与各自的失水率和失水动力学成正相关,肌肉组织失水过程为先快后慢;胃黏膜组织的失水过程为先慢后快;肌肉组织的总失水率大于胃黏膜组织。这表明结构不同的生物组织的光透明效果存在差异,必须考虑其内部结构的影响。     

Medical imaging with a microwave tomographic scanner

A microwave tomographic scanner for biomedical applications is presented. It consists of a 64-element circular array with a useful diameter of 20 cm. Electronically scanning the transmitting and receiving antennas allows multiview measurements with no mechanical movement. Imaging parameters-a spatial resolution of 7 mm and a contrast resolution of 1% for a measurement time of 3 s-are appropriate for medical use. Measurements on tissue-simulating phantoms and volunteers, together with numerical simulations, are presented to assess the system for absolute imaging of tissue distribution and for differential imaging of physiological, pathological, and induced changes in tissues     

Determination of optical properties of superficial volumes of layered tissue phantoms

Previously, we reported the design of a new diffusing probe that employs a standard two-layer diffusion model to recover the optical properties of turbid samples. This particular probe had a source-detector separation of 2.5 mm and performance was validated with Monte Carlo simulations and homogeneous phantom experiments. The goal of the current study is to characterize the performance of this new method in the context of two-layer phantoms that mimic the optical properties of human skin. We analyze the accuracy of the recovered top layer optical properties and their dependences on the thickness of the top layer of two-layer phantoms. Our results demonstrate that the optical properties of the top layer can be accurately determined with a 1.6 mm source-detector separation diffusing probe when this layer thickness is as thin as 1 mm. Monte Carlo simulations illustrate that the interrogation depth can be further decreased by shortening the source-detector separation.     

Multislice tomographic imaging and analysis of human breast-equivalent phantoms and biological tissues

A laser transillumination tomographic system, consisting of electrical, optical, mechanical, and software components, to obtain multislice images of tissue-equivalent breast phantoms and biological tissues, is developed. The tissue-equivalent phantoms are prepared from paraffin wax mixed with wax color pigments by matching their surface backscattered profiles as measured by multiprobe laser reflectometer, with that of respective tissues. The optical parameters of these phantoms are determined by matching their reflectance profiles with that as obtained by Monte Carlo simulation of optical scattering. For multislice tomographic analysis conical breast phantoms of height 80.0 mm and 80.0 mm base diameter with inclusions of different optical properties and dimensions are developed. The resolution of the inclusions in the tomograms depends on their sizes and optical parameters. The minimum size of the inclusion as detected by this procedure in a slice of diameter 50.0 mm is 3.0 mm. The structural variation as observed in the tomograms of phantoms of combination of biological tissues indicates its possible applications in detecting the abnormalities developing in human healthy soft tissues.     

Muscle-equivalent phantom materials for 10-100 MHz

New tissue-simulating materials that are aqueous solutions are described. Glycine is used to obtain the large permittivity of muscle at frequencies below 100 MHz. The lack of suspended solids simplifies preparation, and ensures the dielectric properties are homogeneous, stable, and reproducible. The solutions are transparent, facilitating placement of probes for measuring temperature or electric field. The optical clarity of the phantom mixture may also be desirable in a quick assessment of RF applicators by the use of liquid crystalline display sheets     

基于LS-SVM测量生物组织光学参量的实验研究

为了实现无损测量生物组织光学参量,利用CCD技术结合最小二乘支持向量机,对测量组织模拟液的光学参量进行了实验研究。通过实验测量了组织模拟液的表面漫反射光分布,建立了漫反射光分布与光学参量间的最小二乘支持向量机回归模型,该模型实现了小样本条件下对组织模拟液光学参量的预测误差仅为5%。结果表明,最小二乘支持向量机结合CCD测量技术能够准确测量组织模拟液的光学参量。     

由漫射图像测量生物组织的光学特性

为了获取生物组织的光学特性参量,采用CCD无损测量系统来获得生物组织的漫反射图像,通过数据分析获取组织表面的漫射光分布,首先对具有不同光学特性参最的组织模拟液进行测量,用实验所得数据训练神经网络,并用另一组实验数据对神经网络的有效性和精确度进行了验证,然后对牛肉、猪肉以及人体表皮组织在633nm光照下进行了测量,由经实...