X射线诱导声学计算机断层成像技术及其生物医学应用进展

X射线诱导声学计算机断层成像(XACT)作为近几年来发展起来的生物医学成像手段之一,因其具有低X射线辐射剂量、快速三维成像以及多角度可选采集等优点而受到广泛的欢迎,在生物医学成像方面具有很大的发展潜力。本文总结了XACT的发展背景及研究进程,并对成像原理进行了详细阐述,然后分别对基于单元探测器、环形探测器、半球形探测器以及平面矩形探测器的四种成像模式进行了系统的介绍,同时简单介绍了该技术在乳腺、前列腺及骨密度成像等生物医学领域中的应用。最后,我们对该技术在X射线剂量监控、质子治疗过程监控以及与同步辐射光源结合进行多模态成像等方面做出展望。多模态成像提供的多维、多尺度的影像学信息将为相关疾病的早期发现、诊断以及治疗监控、效果评估等提供重要参考。

随钻声波测井FDTD模拟及钻铤波传播特性研究

幅度大的钻铤波掩盖地层信号是困扰随钻声波测井技术的难题,认识钻铤波特性对于消除或有效降低钻铤波至关重要.记录岩石动电效应引起电磁场的随钻动电测井,被认为有望彻底解决钻铤波干扰问题.本文采用有限差分法,模拟不同钻铤、不同井孔结构的随钻声场,对比分析了单极源钻铤波的传播特性,阐明存在伴随钻铤波动电信号的原因.结果表明:钻铤声波在沿钻铤传播时向外部介质辐射能量,透过井壁进入地层的具有视钻铤波速度的声波,与地层纵横波一样可发生动电转化,因而可导致随钻动电测井时产生钻铤波速度的电磁信号.计算还表明,高频情况下,随钻声波测井钻铤波呈现两阶模式:具有低频截止频率的高阶钻铤波幅度较小,其速度略低于钻铤纵波速度;无截止频率的低阶钻铤波幅度较大,其波速在高频时甚至低于钻铤横波速度.这种频散特性和多阶模式特性,是径向多分层开波导结构的导波属性.

瞬态诱发耳声发射在新生儿听力筛选中的初步应用

目的:研究瞬态诱发耳声发射在新生儿听力筛选中的作用和价值。方法:采用ILO-88型耳动态分析仪测试了112例足月出生,无听力高危因素的新生儿,并用听性脑干反应和小儿行为测听方法进行随访和确诊。结果:112例中首次检测未通过率为8.9%。经过6～8个月随访1例为双耳感音神经性耳聋,检出率为8.8‰。结论:瞬态诱发耳声发射技术在新生儿听力筛选中有非常重要的意义。

强声激励下旋流火焰周期性流动结构的实验研究

强声波扰动下旋流流场的动态特征对于理解旋流火焰的非线性响应特性非常重要。基于超高重复频率脉冲串式激光器高速粒子示踪技术测量了强声激励下旋流火焰的动态流场,研究了旋流流场周期性涡结构和流场-火焰动态相互作用。周期性声波扰动会在旋流火焰内剪切层和外剪切层中引起固有涡结构。发现外部涡环在卷曲火焰锋面和改变火焰热量释放速率中起主要作用,而内部涡环分布在火焰根部并会影响中心回流区速度分布。定量提取了声诱导涡环的轨迹、涡量、环量、尺寸、出口速度以及加速度之间关系,发现强声激励下的出口速度和加速度决定了外部涡环的形成和脱落过程。

Er:YAG激光荡洗的研究与进展

在治疗牙髓病、根尖周病时,根管冲洗对于消毒主根管、根管峡部及侧支根管都是至关重要的。传统的注射器冲洗使用最广泛。由于根管系统错综复杂的三维结构,液体无法渗透到所有区域,所以该方法无法很好地冲走组织残留物、牙本质碎屑及玷污层。这会妨碍根管消毒,并影响根管填充材料的密封性能。激光激活冲洗已经成为一种有效的根管冲洗技术,铒:钇铝石榴石(Er:YAG)激光荡洗大大提高了清除根管内碎屑和消毒药物的效率。该文总结了Er:YAG激光荡洗技术在根管冲洗方面的效果和优势,并综述了Er:YAG激光荡洗技术在根管治疗中的应用现状。

铒激光活化根管冲洗技术的研究进展

根管治疗术是目前治疗牙髓病和根尖周病最有效和最常用的方法,其中根管冲洗是根管治疗的重要组成部分。目前,临床上常常应用注射器、声波、超声波等方法和联合各种冲洗液(生理盐水、NaClO、EDTA等)进行根管冲洗。然而,上述临床方法对根管不规则区域和根尖1/3的冲洗效果尚不能达到理想的临床预期效果。随着对激光研究的不断深入,发现水和羟磷灰石对波长为2940nm的掺铒钇铝石榴石(Er:YAG)激光有高度亲和力。因此,有学者提出利用铒激光活化根管冲洗是提高根管冲洗效果的一种有效手段。本文聚焦于铒激光活化根管冲洗技术的最新研究进展:光子诱导光声流(PIPS)技术和冲击波增强发射光声流(SWEEPS)技术。探讨铒激光活化根管冲洗技术在清除根管内玷污层、牙体硬组织碎屑、根管内细菌、防止冲洗液根尖挤出等方面的能力,并对铒激光活化根管冲洗技术的研究背景、技术原理以及相关临床研究进展进行简要的介绍,以期为临床选择相关根管清洁方式提供新思路。

Er:YAG激光桩道预处理的研究进展

本文回顾了Er:YAG激光活化根管冲洗技术的最新研究进展,包括光子诱导光声流(photon initiated photoacoustic streaming, PIPS)技术和冲击波增强发射光声流(shock wave enhanced emission photoacoustic streaming, SWEEPS)技术,探讨Er:YAG激光预处理桩道的原理、优点以及对纤维桩粘接强度的影响,以期为临床选择适宜的桩道处理方法提供新思路。

Spiral Waves and Multiple Spatial Coherence Resonances Induced by Colored Noise in Neuronal Network

Gaussian colored noise induced spatial patterns and spatial coherence resonances in a square lattice neuronal network composed of Morris-Lecar neurons are studied.Each neuron is at resting state near a saddle-node bifurcation on invariant circle,coupled to its nearest neighbors by electronic coupling.Spiral waves with different structures and disordered spatial structures can be alternately induced within a large range of noise intensity.By calculating spatial structure function and signal-to-noise ratio(SNR),it is found that SNR values are higher when the spiral structures are simple and are lower when the spatial patterns are complex or disordered,respectively.SNR manifest multiple local maximal peaks,indicating that the colored noise can induce multiple spatial coherence resonances.The maximal SNR values decrease as the correlation time of the noise increases.These results not only provide an example of multiple resonances,but also show that Gaussian colored noise play constructive roles in neuronal network.

Ultrasound Elastography of Ethanol-induced Hepatic Lesions:In Vitro Study

Objective To study the value of ultrasound elastography in evaluation of ethanol-induced lesions of liver. Methods Alcohol with a dose of 2 ml was injected into a fresh porcine liver under ultrasound guidance to create stiff necrosis. Then freehand elastography of the lesion from the identical scan plane was obtained with SONOLINE Antares system using VF10-5 probe at about every 30 seconds till 6 minutes later. The original high quality radiofrequency data were acquired through an ultrasound research interface which was provided by the ultrasound system. Then, corresponding elastograms were produced offline using cross-correlation technique and compared with gross pathology findings. Results Gray-scale sonogram showed a hyperechoic area with acoustic shadow below appeared immediately after alcohol injection. The hyperechoic area tended to be diffuse and its boundary to be illegible with time. On the contrary, the ethanol-induced lesion in elastogram appeared as a low swain hard region surrounded by high strain soft hepatic tissues, with clear but irregular boundaries. Sequential elastograms with the sketched lesion boundaries showed that the lesion area increased in the first 3 minutes after ethanol injection, and then reached a plateau which corresponding to gross specimen. Conclusion Ultrasound elastography is capable of detecting and evaluating the diffusion of ethanol-induced hepatic lesion, and more sensitive and accurate than routine sonography.

Spiral Wave in Small-World Networks of Hodgkin-Huxley Neurons

The effect of small-world connection and noise on of Hodgkin-Huxley neurons are investigated in detail. Some the formation and transition of spiral wave in the networks interesting results are found in our numerical studies, i） The quiescent neurons are activated to propagate electric signal to others by generating and developing spiral wave from spiral seed in small area. ii） A statistical factor is defined to describe the collective properties and phase transition induced by the topology of networks and noise, iii） Stable rotating spiral wave can be generated and keeps robust when the rewiring probability is below certain threshold, otherwise, spiral wave can not be developed from the spiral seed and spiral wave breakup occurs for a stable rotating spiral wave. iv） Gaussian white noise is introduced on the membrane of neurons to study the noise-induced phase transition on spiral wave in small-world networks of neurons. It is confirmed that Ganssian white noise plays active role in supporting and developing spiral wave in the networks of neurons, and appearance of smaller factor of synchronization indicates high possibility to induce spiral wave.

Optimal Initialization of a Quantum System for an Efficient Coherent Energy Transfer

For an energy transfer network, the irreversible depletion of excited electron energy occurs through either an efficient flow into an outer energy sink or an inefficient decay. With a small decay rate, the energy transfer efficiency is quantitatively reflected by the average life time of excitation energy before being trapped in the sink where the decay process is omitted. In the weak dissipation regime, the trapping time is analyzed within the exciton population subspace based on the secular Redfield equation. The requirement of the noise-enhanced energy transfer is obtained, where the trapping time follows an exact or approximate 1/F- scaling of the dissipation strength F. On the opposite side, optimal initial system states are conceptually constructed to suppress the 1/F-scaling of the trapping time and maximize the coherent transfer efficiency. Our theory is numerically testified in four models, including a biased two-site system, a symmetric three-site branching system, a homogeneous one- dimensional chain, and an 8-chromophore FMO protein complex.

Effect of Asymmetry of Dichotomous Noise on Transport of Particles

In this paper, an additive dichotomous noise model and a multiplicative dichotomous noise model are investigated for the effect of the asymmetry of the additive and multiplicative dichotomous noises on the transport of the particles, in the presence of spatial symmetry and asymmetry, respectively. It is shown that, in the presence of spatial asymmetry, the asymmetry of the dichotomous noise can weaken or enhance the transport of the particles; while in the absence of spatial asymmetry, the nonzero current induced by the noise＇s asymmetry is ＂symmetric＂ around the zero current. In addition, a current reversal can be produced by controlling the noise＇s asymmetry parameter; and we find that, for some values of the noise＇s asymmetry parameter, the multiplicative dichotomous noise can more easily induce the transport of the particles than the additive dichotomous noise.

Simulation of thermal field induced by concave spherical transducer in multi-layer media

High intensity focused ultrasound(HIFU)therapy is an effective method in clinical treatment of tumors,in order to explore the bio-heat conduction mechanism of in multi-layer media by concave spherical transducer,temperature field induced by this kind of transducer in multi-layer media will be simulated through solving Pennes equation with finite difference method,and the influence of initial sound pressure,absorption coefficient,and thickness of different layers of biological tissue as well as thermal conductivity parameter on sound focus and temperature distribution will be analyzed,respectively.The results show that the temperature in focus area increases faster while the initial sound pressure and thermal conductivity increase.The absorption coefficient is smaller,the ultrasound intensity in the focus area is bigger,and the size of the focus area is increasing.When the thicknesses of different layers of tissue change,the focus position changes slightly,but the sound intensity of the focus area will change obviously.The temperature in focus area will rise quickly before reaching a threshold,and then the temperature will keep in the threshold range.

ECG stress test induced atrial ischemia in a patient with old inferior myocardial infarction due to a distal coronary artery lesion

A 78-year-old man with a history of mitral valve prolapse underwent echocardiography during his cardiological check-up examination in 2011 in a symptom-free stage. Echocardiography revealed akinesis of the inferior septum and inferobasal free wall as a novel finding suggesting a distal right coronary artery （RCA） lesion （Figure 1）. The systolic left ventricular function was normal. Earlier echocardiographies did not show wall motion abnormalities.

马来酸依那普利致声音嘶哑

1病历摘要男,60岁。以声音嘶哑2个月、加重1周为主诉入院。患者于入院前2个月出现声音嘶哑,症状呈波动性,似乎晨起较轻,每日9：00后加重,尤为进食后。与劳累无关,无进食呛咳,无吞咽困难。无头晕头痛,无恶心呕吐。

Er∶YAG激光光子增强的光声流效应技术清理根管玷污层效果的体外研究

目的观察不同Er∶YAG激光技术对根管内壁玷污层的清理能力,探究光子增强的光声流效应(shock wave enhanced emission photoacoustic streaming,SWEEPS)技术对根管内壁玷污层的清理效果。方法示波器精确测定Er∶YAG激光不同工作模式的脉冲波形。收集人离体第三磨牙(85颗),使用机用ProTaper Universal镍钛锉进行根管预备至30号(锥度0.09),建立玷污层模型,并使用5.25%次氯酸钠在预备过程中进行冲洗。分别应用Er∶YAG激光SWEEPS技术与光子诱导的光声流效应(photon-induced photoacoustic streaming,PIPS)技术激活17%EDTA,清理离体牙根管内壁玷污层30 s和60 s。将激光激活荡洗后的样本沿牙体组织长轴纵向劈开,扫描电镜分别观察距离根尖孔1、4及8 mm的根管内表面并进行评分。红外热像仪记录两种不同Er∶YAG激光技术激活荡洗时离体牙外表面的温度变化。结果 SWEEPS技术是一种双脉冲Er∶YAG激光工作模式,该技术对距离根尖孔4 mm及1 mm的玷污层清理效果优于PIPS技术(P <0.05)。红外热像仪检测发现两种Er∶YAG激光技术在激活荡洗过程中对牙周膜的热负效应差异无统计学意义(P> 0.05)。结论与PIPS技术相比,应用Er∶YAG激光SWEEPS技术可对根中段及根尖段玷污层有更好的清理效果,同时不增加对牙周膜的热负效应。

利用SEM观察Er:YAG激光活化冲洗对根管内玷污层清理效果的体外研究

目的:通过扫描电子显微镜(scanning electron microscope, SEM)观察3%次氯酸钠联合Er:YAG激光活化冲洗对根管内玷污层的清除效果。方法:选择40颗离体前磨牙,采用机动ProTaper镍钛锉进行根管预备至F3后根据处理方案的不同随机分为4组(n=10)。A组:5 mL 0.9%生理盐水处理60 s;B组:5 mL 3%次氯酸钠溶液处理60 s;C组:5 mL 17%EDTA溶液处理60 s;D组:5 mL 3%次氯酸钠溶液+Er:YAG激光活化冲洗60 s。用SEM观察根管内玷污层的去除情况并进行评分。结果:D组玷污层清除效果优于A、B、C组,差异具有统计学意义(P<0.05);同组内根管内玷污层的清除情况为根上1/3>根中1/3>根尖1/3;D组在根尖1/3玷污层的去除效果显著优于A、B、C组;差异均有统计学意义(P<0.05)。结论:3%次氯酸钠联合Er:YAG激光活化冲洗可更有效去除根管内玷污层,相较于传统化学冲洗方法,在清理根尖1/3处玷污层时更具优势。

Parameter Diversity Induced Multiple Spatial Coherence Resonances and Spiral Waves in Neuronal Network with and Without Noise

Diversity in the neurons and noise are inevitable in the real neuronal network.In this paper,parameter diversity induced spiral waves and multiple spatial coherence resonances in a two-dimensional neuronal network without or with noise are simulated.The relationship between the multiple resonances and the multiple transitions between patterns of spiral waves are identified.The coherence degrees induced by the diversity are suppressed when noise is introduced and noise density is increased.The results suggest that natural nervous system might profit from both parameter diversity and noise,provided a possible approach to control formation and transition of spiral wave by the cooperation between the diversity and noise.

不同根管冲洗方法及冲洗时间对管间峡区清理效果的研究

目的 比较4种根管冲洗方法对3D打印树脂牙管间峡区的清理效果,并优化冲洗时间参数。方法 研究于2021年11月至2022年6月在深圳市人民医院口腔医学中心实验室进行。选取80颗预备后的具有相同管间峡区的3D打印树脂牙经简单随机抽样分成4组,每组20颗,分别记为侧方冲洗组(使用传统的侧方注射器冲洗)、超声组[使用超声活化冲洗(ultrasonically activated irrigation,UAI)系统冲洗]、EDDY声波组(使用EDDY声波活化系统冲洗)、PIPS激光组[使用光子诱导光声流(photon-initiated photoacoustic streaming,PIPS)激光系统冲洗]。将4组树脂牙按照分组方式进行终末冲洗(单次冲洗时间为20 s)后,测量并比较管间峡区内容物剩余长度和冲洗液渗入长度。再选取60颗预备后的具有相同管间峡区的3D打印树脂牙随机分为3组,每组20颗,根据单次冲洗时间记为5 s组、10 s组和30 s组,选用管间峡区内容物剩余长度和冲洗液渗入长度测量结果最优的根管冲洗方法进行冲洗,并比较各冲洗时间组管间峡区清理效果指标。结果 各根管冲洗方法组管间峡区的内容物剩余长度、冲洗液渗入长度总的比较,差异均有统计学意义(F值分别为20.470、16.571,均P <0.001);其中,EDDY声波组、PIPS激光组管间峡区的内容物剩余长度小于侧方冲洗组和超声组,冲洗液渗入长度大于侧方冲洗组和超声组,且EDDY声波组的这两项清理效果指标结果还优于PIPS激光组,差异均有统计学意义(均P <0.05)。使用EDDY声波活化系统冲洗的各冲洗时间组管间峡区清理效果比较,仅内容物剩余长度总的比较,差异有统计学意义(F=13.441,P <0.001)。其中,EDDY声波组(单次冲洗时间为20 s)管间峡区内容物剩余长度显著少于5 s组、10 s组和30 s组,30 s组内容物剩余长度小于5 s组,差异均有统计学意义(均P <0.05);其他各冲洗时间组间比较,差异无统计学意义(P> 0.05)。结论 3种新型辅助根管冲洗方法对管间峡区的清理效果均优于传统侧方注射器冲洗,其中以使用EDDY声波活化系统冲洗且单次冲洗时间为20 s时对管间峡区的清理效果较佳。

Lévy noise induced stochastic resonance in an FHN model

This paper aims to investigate the stochastic resonance （SR） in an FitzHugh-Nagumo （FHN） model with an additive LEvy noise numerically. The non-Gaussian LEvy noise is a kind of general random noise which is different from the usual Gaussian noise, and it has small fluctuations with the unpredictable jumps to describe the random fluctuations in an FHN model. SR is determined by the signal-to-noise ratio （SNR）, and the numerical simulation results show the occurrence of the SR phenomena in the given FHN system. The influence of various parameters of the LEvy noise and the FHN model on the SR will be exam- ined, and some mechanisms of the LEvy noise-induced SR are presented which are different from those of the Gaussian noise.