非致冷红外焦平面成像系统辐射测温技术研究

为了消除由非致冷红外焦平面自身温度变化造成的辐射测温偏差,提出了一种基于G-t(黑体辐射灰度-探测器工作温度)标准曲线进行辐射测温的新方法.该方法从热辐射理论和热像仪测温原理出发,利用实验测得的G-t标准温度关系曲线,并结合灰体表面真实温度的计算公式,最终实现了非致冷红外焦平面成像系统的高精度辐射测温.实验结果表明,当...     

基于Web端多节点红外热成像传感系统设计

随着全球新冠肺炎疫情的持续蔓延,非接触式测温在异常温度筛查中起到重要作用.针对目前红外热成像装置兼容性、便携性较差等问题,提出一种基于Web端的红外热成像多终端非接触测温方法.首先,将传感器获取到的数据经微处理器换算后得到温度矩阵存储在TF卡缓存文件中,之后采用动态颜色映射的方法利用Web技术将温度矩阵数据转换成对应的...     

红外人体测温精度补偿方法研究

针对现有人体测温方案测量精度低,使用条件受限等问题,研究了基于红外热成像的无接触人体测温精度补偿方法。综合考虑测温器件,测温环境对测量精度的影响,为解决常规测量方法存在的红外相机输出值随时间发生漂移,红外相机存在周期性斩波信号,温度测量距离不断变化,温度输出值存在频域噪声等多种问题,提出了综合性的温度测量精度补偿方法,有效降低了温度测量的误差。实验表明,通过本文的精度补偿方法,在不同距离下的人体温度测量误差不超过±0.2℃,可以实现人体温度的精确测量。     

基于红外测温的电气控制柜内部元件热缺陷严重程度的反问题识别

根据国家相关标准建立了电气控制柜内部元件发热故障的判断方法和标准.结合红外辐射理论分析了控制柜内部过热元件对壳体内表面的热辐射,得到了壳体内表面的辐射热流密度,并针对受热壳体建立了二维热传导模型.基于壳体表面的红外成像测温数据,运用L-M算法进行了导热反问题模拟研究,准确求解了控制柜内部元件在不同热缺陷程度时的发热温度...     

基于红外热像的钢水测温模型研究

基于热辐射测温原理,介绍了红外热像仪测温理论,为了提高钢水的测温精度,搭建了实验平台,经过实验获得不同温度下钢水的红外图像。利用Matlab软件提取图像的灰度均值,用最小二乘法和BP神经网络进行温度-灰度拟合曲线,从而得到红外热像测温的模型,使钢水测温误差达到了1%,最终达到测量精度和设计要求,此方法为熔融金属在线红外热像测温的研究打下了坚实的基础。     

基于近场光纤探针的活细胞无损测温方法研究

高精度的单细胞温度分布检测对于研究生命活动具有重要意义。为了实现高空间分辨率、高温度灵敏度的细胞测温,本研究团队基于原子力显微镜的扫描成像原理,将对温度敏感的量子点与音叉驱动的近场光纤探针相结合,提出了一种无损伤测量活细胞表面温度分布的方法;并以人脑星形胶质母细胞瘤细胞为研究对象,利用该方法检测了吞金纳米颗粒的固定细胞和未内吞金纳米颗粒的活细胞的温度分布。结果表明：在无金纳米颗粒作为附加热源的情况下,由活细胞内部产热引起的细胞表面最大温差超过0.5℃,而细胞与其外部环境间的温差大于2.5℃。所提活细胞无损测温方法的空间分辨率小于0.2μm,温度分辨率为0.16 nm/℃,为活细胞温度分布成像提供了新思路。     

无扫描宽范围多波长成像测温技术

多波长测温是一种先进的辐射测温技术,其原理是假定发射率光谱模型,利用测得的多波长辐射与波长发射率函数关系,求得目标的真温和发射率。多波长成像测温技术通过探测目标的多波长辐射图像信息,反演计算得到目标的温场分布。针对基于彩色CCD的多波长成像测温不能适应非线性光谱发射率模型、测温动态范围较窄等不足,提出了一种基于光阑处非等比例滤色分光的四波长无扫描成像测温方法,有效压缩了波段成像带宽,形成了四个窄波段的成像探测,适用于非线性光谱发射率模型目标宽动态范围温场测量。根据提出的测温方法研制了四波长成像测温仪。测温仪主要由窗口、中性衰减片、四色滤光片、光学物镜镜头、可见/近红外集成传感器、测量控制单元及软件等部分组成。测温仪软件由目标四个波长的单色成像图像,得到目标的真温温场分布。在激光加热条件下对800~2500 ℃目标高温温场进行了试验测试,测量结果与热电偶数据比对表明误差小于1%,具有较高的准确度和较好的动态范围适应性。     

非线性灰度变换算法在红外测温系统中的应用

在红外测温系统中,针对传统线性灰度变换带来的测温误差,提出一种非线性灰度变换方法。该方法以探测单元非线性响应模型为基础,建立了非线性响应输出灰度值与温度值的计算公式,以解决输出动态范围小,线性灰度变换带来的测温误差大的缺点。理论分析表明:非线性灰度变换算法能够有效提高红外成像系统的测温精确度,在实际工程中具有较大的应用价值。     

红外热成像测温技术

本文在对热成像测温基本原理分析的基础上,进一步分析了热成像测温的误差及其校正方法,利用面源黑体对热像仪进行辐射定标,通过Qt软件在上位机上设计了一套基于非制冷红外热像仪的测温系统。     

基于表面测温等方差拟合的管内流量及温度识别

基于表面测温的管内流量及温度识别问题在红外无损检测领域还处于起步阶段，是目前红外无损检测技术从定性向定量发展的关键理论基础。针对目前流量识别结果较温度识别结果差和基于最小二乘拟合的识别方法精度有限的问题，使用Gnielinski关联式建立管道充分发展段的一维传热模型，并采用Levenberg-Marquardt （L-M）算法根据表面检测温度进行管内流体流量及温度的识别。通过理论推导和具体算例得，待识别参数的相对识别误差值与参数灵敏度最大值和参数真实值乘积的绝对值成反比关系，含测温误差的温度分布与基于最小二乘拟合得到的温度分布之间的方差不等于测温误差标准偏差的平方与测温点个数的乘积，同时提出了基于表面测温等方差拟合的管内流量及温度的识别方法。数值实验证明该方法在存在测温误差时仍可以精确识别出管内流量及温度。     

Temperature retrieval algorithm for brain temperature monitoringusing microwave brightness temperatures

A solution to the inverse problem of retrieving temperature from a set of microwave brightness temperatures together with a priori information regarding weighting functions and heat transfer within the infant head is introduced. The method offers the basis for non-invasive temperature monitoring appropriate for hypothermal neural rescue therapy     

Absolute Temperature Monitoring Using RF Radiometry in the MRI Scanner

Temperature detection using microwave radiometry has proven value for noninvasively measuring the absolute temperature of tissues inside the body. However, current clinical radiometers operate in the gigahertz range, which limits their depth of penetration. We have designed and built a noninvasive radiometer which operates at radio frequencies (64 MHz) with ~100-kHz bandwidth, using an external RF loop coil as a thermal detector. The core of the radiometer is an accurate impedance measurement and automatic matching circuit of 0.05 Omega accuracy to compensate for any load variations. The radiometer permits temperature measurements with accuracy of plusmn0.1degK, over a tested physiological range of 28degC-40 degC in saline phantoms whose electric properties match those of tissue. Because 1.5 T magnetic resonance imaging (MRI) scanners also operate at 64 MHz, we demonstrate the feasibility of integrating our radiometer with an MRI scanner to monitor RF power deposition and temperature dosimetry, obtaining coarse, spatially resolved, absolute thermal maps in the physiological range. We conclude that RF radiometry offers promise as a direct, noninvasive method of monitoring tissue heating during MRI studies and thereby providing an independent means of verifying patient-safe operation. Other potential applications include titration of hyper- and hypo-therapies     

3.5μm KTiOAsO4光参量振荡器温度调谐特性

对3.5μm KTiOAsO₄光参量振荡器(KTA-OPO)的温度调谐性能进行研究,仿真计算不同温度下KTA的相位匹配曲线,以及光束与z轴的夹角θ与调谐斜率的对应关系。仿真结果表明,随着θ值的增大,闲频光的峰值波长呈单调递增的趋势,调谐斜率呈单调递减的趋势,且I类相位匹配的调谐斜率普遍大于Ⅱ类。对于非临界相位匹配(NCPM)KTA-OPO,对其温度调谐性能进行理论和实验研究。实验结果表明,当温度从30℃升高到180℃时,在II类相位匹配的条件下,闲频光的峰值波长从3463nm移动到3474nm,调谐斜率为0.073nm/℃,理论上的调谐斜率为0.077nm/℃,实验与理论计算结果相符,说明非临界相位匹配KTA-OPO在不同温度下的中红外闲频光输出波长受到温度的影响小,环境适应性强。     

MRI-Compatible Pneumatic Robot for Transperineal Prostate Needle Placement

Magnetic resonance imaging (MRI) can provide high-quality 3-D visualization of prostate and surrounding tissue, thus granting potential to be a superior medical imaging modality for guiding and monitoring prostatic interventions. However, the benefits cannot be readily harnessed for interventional procedures due to difficulties that surround the use of high-field (1.5T or greater) MRI. The inability to use conventional mechatronics and the confined physical space makes it extremely challenging to access the patient. We have designed a robotic assistant system that overcomes these difficulties and promises safe and reliable intraprostatic needle placement inside closed high-field MRI scanners. MRI compatibility of the robot has been evaluated under 3T MRI using standard prostate imaging sequences and average SNR loss is limited to 5%. Needle alignment accuracy of the robot under servo pneumatic control is better than 0.94 mm rms per axis. The complete system workflow has been evaluated in phantom studies with accurate visualization and targeting of five out of five 1 cm targets. The paper explains the robot mechanism and controller design, the system integration, and presents results of preliminary evaluation of the system.     

采矿工人生理状况监测系统设计

采矿工人生理状况监测系统是工人矿井下作业时,进行实时、连续、长时间地采集、监测心电、呼吸、体温、血氧饱和度和体动等参数,并实现数据无线传输的系统。针对传统监控设备对工人状态掌控缺乏、矿难频发等重大问题,设计了一款无线、可穿戴、无创、低心理负荷的多参数采矿工人生理状况监测系统,以便准确地了解井下工人生理状况,及时预防危险状况发生,安全顺利地完成采矿工作。     

RF field visualization of RF ablation at the Larmor frequency

Radio-frequency ablation (RFA) is an effective minimally invasive treatment for tumors. One primary source of difficulty is monitoring and controlling the ablation region. Currently, RFA is performed at 460 kHz, for which magnetic resonance imaging (MRI) could play a role given its capability for temperature monitoring and tumor visualization. If instead the ablation were to be performed at the MRI Larmor frequency, then the MR capability for B(1) field mapping could be used to directly visualize the radio-frequency (RF) fields created by the ablation currents. Visualizing the RF fields may enable better control of the ablation currents, enabling better control of lesion shape and size and improving repeatability. We demonstrate the feasibility of performing RFAs at 64 MHz and show preliminary results from imaging the RF fields from the ablation. The post-ablation RF fields show an increase in current density in the ablated region, consistent with an increase in conductivity of the ablated tissue.     

Methods for providing probe position and temperature information onMR images during interventional procedures

Interventional magnetic resonance imaging (MRI) can be defined as the use of MR images for guiding and monitoring interventional procedures (e.g., biopsy, drainage) or minimally invasive therapy (e.g., thermal ablation). This work describes the development of a prototype graphical user interface and the appropriate software methods to accurately overlay a representation of a rigid interventional device [e.g., biopsy needle, radio-frequency (RF) probe] onto an MR image given only the probe's spatial position and orientation as determined from a three-dimensional (3-D) localizer used for interactive scan plane definition. This permits 1) “virtual tip tracking”, where the probe tip location is displayed on the image without the use of separate receiver coils or a “road map” image data set, and, 2) “extending” the probe to predict its path if it were directly moved forward toward the target tissue. Further, this paper describes the design and implementation of a method to facilitate the monitoring of thermal ablation procedures by displaying and overlaying temperature maps from temperature sensitive MR acquisitions. These methods provide rapid graphical updates of probe position and temperature changes to aid the physician during the actual interventional MRI procedures without altering the usual operation of the MR imager     

近红外光谱技术在激光热疗监测中的应用研究

针对激光热疗中生物病变组织光学参数随温度变化的特点,将近红外光谱技术应用于激光诱导肿瘤间质热疗疗效监测,在线检测激光作用后生物病变组织的温度与光学参数的变化趋势,以此来对疗效进行评估。基于监测原理分析,设计实验系统,以肝癌小鼠皮下移植瘤为实验对象,研究不同激光功率和作用时间下,生物病变组织约化散射系数和温度的变化,并利用核磁共振成像技术对移植瘤术前、术后的影像进行对比。实验结果表明:病变组织的约化散射系数在激光热疗过程中呈上升趋势,起始阶段上升较快,达到一定数值后趋于稳定,整体变化趋势与温度变化趋势比较吻合,核磁影像对比也证实了治疗效果。因此,通过近红外光谱技术监测激光热疗中病变组织约化散射系数的变化可有助于指导临床激光热疗。     

Superparamagnetic Liposomes for MRI Monitoring and External Magnetic Field‐Induced Selective Targeting of Malignant Brain Tumors

Magnetic‐fluid‐loadedliposomes (MFLs) of optimized magnetic responsiveness are newly worked out from the entrapment of superparamagnetic maghemite nanocrystals in submicronic PEG‐ylated rhodamine‐labelled phospholipid vesicles. This nanoplatform provides an efficient tool for the selective magnetic targeting of malignant tumors localized in brain and non‐invasive traceability by MRI through intravascular administration. As assessed by in vivo 7‐T MRI and ex vivo electron spin resonance, 4‐h exposure to 190‐T m^–1 magnetic field gradient efficiently concentrates MFLs into human U87 glioblastoma implanted in the striatum of mice. The magnetoliposomes are then longer retained therein as checked by MRI monitoring over a 24‐h period. Histological analysis by confocal fluorescence microscopy confirms the significantly boosted accumulation of MFLs in the malignant tissue up to the intracellular level. Electron transmission microscopy reveals effective internalization by endothelial and glioblastoma cells of the magnetically conveyed MFLs as preserved vesicle structures. The magnetic field gradient emphasizes MFL distribution solely in the tumors according to the enhanced permeability and retention (EPR) effect while comparatively very low amounts are recovered in the other cerebral areas. Such a selective targeting precisely traceable by MRI is promising for therapeutic applications since the healthy brain tissue can be expected to be spared during treatments by deleterious anticancer drugs carried by magnetically guided MFLs.     

用于检测皮瓣移植术后血红蛋白浓度的多方位反射式无创测试系统

血红蛋白浓度作为衡量皮瓣移植手术部位恢复状 况的重要指标,能较好地反映血液流通状态。目前 常见的术后血运监测方法限于对皮肤温度、颜色和肿胀程度等物理观察和经验诊断,或仅通 过血氧饱和度 粗略判断,未见对血红蛋白浓度的实时监测。本文设计并搭建了一种用于检测皮瓣移植术后 血红蛋白浓度 的多方位反射式无创测试系统,通过对样本数据的采集分析引入修正系数,实现了血红蛋白 浓度的无创检 测。实验结果表明,6名志愿者连续10次测量结果的标准偏差较小; 40组测量值与真值的相关性良好;皮 肤加热后采集的血红蛋白浓度对温度变化灵敏,说明系统具有较好的稳定性、精确性和有效 性。项目组将 与河南大学淮河医院合作,对皮瓣移植术后患者的血红蛋白浓度进行临床检测,进一步校准 数据并研发小 型化便携式测量仪器,为术后护理提供更加可靠的依据。