磁共振成像系统(MRI)主磁场强度示值误差的测量结果不确定度

为了使医用磁共振成像系统(MRI)主磁场强度示值误差的测量结果不确定度评定合理,基于用高准确度等级磁场强度检测仪测量主磁场强度的数学模型,对其测量不确定度来源进行分析,列出了方差、灵敏系数及标准不确定度公式,从而给出了主磁场强度示值误差的合成不确定度和扩展不确定度。     

医用磁共振成像系统磁场强度示值误差测量结果不确定度评定

本文介绍了医用磁共振成像系统磁场强度示值误差测量结果的不确定度评定方法。     

医用诊断X射线辐射源空气比释动能率测量结果不确定度评定

医用诊断X射线辐射源是一种医院临床诊断和治疗中广泛使用的强制检定计量器具。文章采用9206E型医用诊断X射线辐射源检定装置作为主标准器,依据JJG 744—2004 《医用诊断X射线辐射源检定规程》、JJF 1059.1-2012《测量不确定度评定与表示》对X射线辐射源空气比释动能率测量结果不确定度进行评定,以确定其测量结果的准确性。     

医用原子吸收光谱仪灵敏度的测量不确定度评定

目的:为制定JJF (川) 163-2020《原子吸收多元素分析仪(医用)校准规范》,必须对医用原子吸收光谱仪的灵敏度评定测量不确定度。方法:建立了医用原子吸收光谱仪灵敏度的测量模型,建立了校准方法,分析了不确定度的来源,并分别评定了火焰原子化器和石墨炉原子化器的铜,锌,钙,镁,铁,钾,钠,铅和镉的不确定度。结果:铁元素的不确定度U=0. 004,其它元素的U=0. 003,k=2。结论:为医用原子吸收光谱仪评定灵敏度的测量不确定度,可以为编制医用原子吸收光谱仪的校准规范提供技术支持,并有着重要意义。     

药用低密度聚乙烯膜拉伸性能测试的不确定度评定

目的 对药用低密度聚乙烯膜的拉伸强度和断裂伸长率的测试结果进行不确定度评定。方法 依据JF1059.1-2012《测量不确定度评定与表示》,分析测量拉伸性能方法的不确定度来源,建立数学模型量化不确定度分量,计算合成标准不确定度。结果 拉伸强度的测量不确定度,纵向为（17±1）MPa,k=2;横向为（38±2）MPa,k=2。断裂伸长率的测量不确定,纵向为（181±5）%,k=2;横向为（470±23）%,k=2。结论在温湿度等条件不变的情况下,重复性测量对于不确定度结果的影响最大。     

空气比释动能测量值的不确定度评定

医用数字摄影(CR、DR)系统是医疗机构中最常见、最常用的检测设备，其准确性直接影响检测结果。本文根据JJF 1059.1-2012《测量不确定度评定与表示》,对DR系统中空气比释动能测量值不确定度因素进行分析与不确定度评定。     

医用数字摄影(CR、DR)系统X射线辐射源空气比释动能测量值的不确定度评定

本文分析了医用数字摄影(CR、DR)系统X射线辐射源空气比释动能测量值不确定度的主要来源,介绍了医用数字摄影(CR、DR)系统X射线辐射源空气比释动能测量值不确定度的评定步骤和方法,给出了评定结果。     

医用CT剂量指数测量结果的不确定度评定

为了使医用诊断计算机断层摄影装置（CT）X射线辐射源在模体中的剂量指数测量结果的不确定度评定合理。基于用带有100mm长杆电离室的积分剂量仪测量CT剂量指数的数学模型,对其测量不确定度来源进行分析,列出了方差、灵敏系数及标准不确定度的计算公式,从而给出了CT剂量指数测量的合成标准不确定度和扩展不确定度。     

医用诊断（CT）X射线辐射源剂量指数测量值不确定度的评定

本文介绍了医用诊断（CT）X射线辐射源剂量指数测量结果不确定度的评定及表达方式。     

卷烟主流烟气中烟碱测量不确定度的评定

依据测量不确定度评定指南,对卷烟主流烟气中烟碱的各测量不确定度分量进行评定,得出扩展不确定度（k=2）的结果为0.08mg;气相色谱测定标准工作曲线拟合是测量不确定度的最大影响因素,实验中应加以重视以确保测量结果的有效可靠。     

An investigation of the uncertainty in reproducing the units of pulsed electric and magnetic field strengths in a standard system for producing very-short electromagnetic pulses with a rise time of 20 psec

A method of reproducing the units of pulsed electric and magnetic field strength in a standard system with a pulse rise time of less than 20 psec, constructed using a “cone over a plane” field-generating system is considered. The components of the uncertainty in reproducing the units are analyzed. The extended uncertainty is not greater than 6.5%.     

低场永磁MRI导引聚焦超声肿瘤消融系统的研究

研究了低场永磁磁共振(Magnetic Resonance Imaging,MRI)导引的高强度聚焦超声(High Intensity Focused Ultrasound,HIFU)系统,使两者融合为一体。把磁共振的磁体设计为U字形,这样HIFU治疗头就可以放置于磁共振开口的上方;同时,在磁兼容、磁共振的快速成像、磁共振的测温、相控阵换能器、HIFU的治疗计划等方面做了一些研究。研究结果表明,在低场永磁的磁共振导引下,可以实现系统的所有设计功能,系统定位的图像比上一代B超导引的HIFU清晰,提高了实用性。     

Modified Global Flower Pollination Algorithm‐based image fusion for medical diagnosis using computed tomography and magnetic resonance imaging

Recently, the computed tomography (CT) and magnetic resonance imaging (MRI) medical image fusion have turned into a challenging issue in the medical field. The optimal fused image is a significant component to detect the disease easily. In this research, we propose an iterative optimization approach for CT and MRI image fusion. Initially, the CT and MRI image fusion is subjected to a multilabel optimization problem. The main aim is to minimize the data and smoothness cost during image fusion. To optimize the fusion parameters, the Modified Global Flower Pollination Algorithm is proposed. Here, six sets of fusion images with different experimental analysis are evaluated in terms of different evaluation metrics such as accuracy, specificity, sensitivity, SD, structural similarity index, feature similarity index, mutual information, fusion quality, and root mean square error (RMSE). While comparing to state‐of‐art methods, the proposed fusion model provides best RMSE with higher fusion performance. Experiments on a set of MRI and CT images of medical data set show that the proposed method outperforms a very competitive performance in terms of fusion quality.     

Towards Single Biomolecule Imaging via Optical Nanoscale Magnetic Resonance Imaging

Nuclear magnetic resonance (NMR) spectroscopy is a physical marvel in which electromagnetic radiation is charged and discharged by nuclei in a magnetic field. In conventional NMR, the specific nuclei resonance frequency depends on the strength of the magnetic field and the magnetic properties of the isotope of the atoms. NMR is routinely utilized in clinical tests by converting nuclear spectroscopy in magnetic resonance imaging (MRI) and providing 3D, noninvasive biological imaging. While this technique has revolutionized biomedical science, measuring the magnetic resonance spectrum of single biomolecules is still an intangible aspiration, due to MRI resolution being limited to tens of micrometers. MRI and NMR have, however, recently greatly advanced, with many breakthroughs in nano‐NMR and nano‐MRI spurred by using spin sensors based on an atomic impurities in diamond. These techniques rely on magnetic dipole–dipole interactions rather than inductive detection. Here, novel nano‐MRI methods based on nitrogen vacancy centers in diamond are highlighted, that provide a solution to the imaging of single biomolecules with nanoscale resolution in‐vivo and in ambient conditions.     

水听器法的医用超声声场参数测量不确定度分析

提出了一种基于水听器法测量医用超声声场参数的测量装置,可通过扫描声场获取IEC 61157国际标准所要求的声场中峰值负声压等医用超声诊断设备的声输出参数.同时以一种B型超声诊断仪为例,对声场中声压的测量不确定度进行分析,分别给出A类、B类测量不确定度及标准不确定度,并对影响测量结果的主要因素进行了评定,得出当声压测定结果为1.456 4MHz时,其最小扩展不确定度可为0.215 0MHz.     

焦耳天平（量子质量基准）磁场系统的不确定度分析

基于焦耳天平激励线圈系统的具体结构,分析了磁场系统几何中心磁场强度的不确定度分量,磁场的相对合成标准不确定度ΔH/H达到1.8×10^-3。证明了影响焦耳天平磁场最大的不确定度分量来源于线圈中加载电流的不确定度u(I),它对磁场的相对合成标准不确定度ΔH/H影响达到1.8×10^-3,因此推荐采用高稳定的恒流源来较少焦耳天平磁场的不确定度。     

Decay time characteristics of La2O2S:Eu and La2O2S:Tb for use within an optical sensor for human skin temperature measurement

We focus on the development of a remote temperature sensing technology, i.e., an optical laser-based sensor, using thermographic phosphors for medical applications, particularly within an electromagnetically hostile magnetic resonance imaging (MRI) environment. A MRI scanner uses a strong magnetic field and radio waves to generate images of the inside of the body. The quality of the image improves with increasing magnetic resonance; however, the drawback of applying a greater magnetic strength is the inducement of heat into the body tissue. Therefore, monitoring the patient's temperature inside MRI is vital, but until now, a practical solution for temperature measurement did not exist. We show europium doped lanthanum oxysulphide (La(2)O(2)S:Eu) and terbium doped lanthanum oxysulphide (La(2)O(2)S:Tb) are both temperature sensitive to a low temperature range of 10-50 degrees C when under ultraviolet (UV) excitation. The emission spectra and decay time characteristics of these phosphors were demonstrated. The results indicate that La(2)O(2)S:Eu has a quenching rate of 13.7 m degrees C(-1) and 4 m degrees C(-1) at 512 nm and 538 nm, respectively. In addition, La(2)O(2)S:Tb has a lower quenching rate of 4.19 m degrees C(-1) at 548 nm due to its faster decay time.     

Improvement of magnetic induction-wire sawing process using a magnetic system

Magnetic induction-free abrasive wire sawing is a hybrid process that applies a homogeneous magnetic field to transport more abrasives into the sawing channel. This causes the performance of wire sawing significantly improved. Magnetic field strength is a key factor in determining the magnetic force acting on the magnetic abrasives, then affecting the quantity of abrasives adsorbed on the saw wire surface. However, the background magnetic induction strength produced by two permanent magnets is limited in this process. To further investigate the influence of magnetic field strength on the wire sawing performance, a magnetic system, which is based on the magnetic circuit design principle and the structure of single-wire sawing machine, is designed and fabricated. The magnetic field characteristics of the designed magnetic system are investigated both by numerical simulations and experiments. An experimental setup that installs the fabricated magnetic system on the single-wire sawing machine is built to conduct the magnetic induction-wire sawing experiments. The results show that the optimal magnetic induction strength is about B₀?=?135?mT. In this case, the kerf loss is decreased by 10% compared to the free abrasive wire sawing technology without a magnetic field.     

Magnetic properties of Ni–Co–Cr-base Elgiloy

The Ni–Co–Cr-base Elgiloy is one of the commonly used engineering materials. Most applications rely on its high strength, ductility, corrosion resistance and excellent fatigue life over a wide temperature range. However, in the medical application of cerebral aneurysm clips, the alloy is often subjected to strong magnetic fields associated with magnetic resonance imaging (MRI). Its paramagnetic behavior meets MRI safety requirements, but is the source of relatively large artifacts and thus less MRI-compatible for MRI procedure involving the brain. This article reports superconducting quantum interference device (SQUID) measurements on the magnetic properties of a series of Elgiloy wires in either as-drawn or heat-treated conditions. Furthermore, low-temperature calorimetry was employed to reveal the existence of submicroscopic clusters containing ferromagnetic elements such as Ni or Co in the macroscopically paramagnetic matrix. © 1999 Kluwer Academic Publishers     

计算机核磁共振成像技术研究

磁共振成像(Magnetic Resonance Imaging简称MRI),是继CT之后医学影像诊断技术的又一重大进展。它的基本原理来自于1946年美国学者Bloch和Purcell的发现:在外磁场的作用下,某些绕主磁场(外磁场)进动的自旋的质子(包括人体中的氢质子)在短暂的射频电波作用下,进动角增大,当射频电波停止后,那些质子又会逐渐恢复到原来的状态,并同时释放与激励波频率相同的射频信号,这一物理现象被称为核磁共振。Bloch和Purcell因这一贡献而获得1952年的诺贝尔物理奖。时隔27年后,英国学者Lauterbur利用这一原理,通过在主磁场中附加一个梯度磁场,并逐点诱发核磁共振无线电波,然后经过复杂的计算机处理与重建,获得一幅二维的磁共振图像。