Anisotropy of Trabecular Bone from Ultra-Distal Radius Digital X-Ray Imaging: Effects on Bone Mineral Density and Age

Background: When applied to trabecular bone X-ray images, the anisotropic properties of trabeculae located at ultra-distal radius were investigated by using the trabecular bone scores (TBS) calculated along directions parallel and perpendicular to the forearm. Methodology: Data from more than two hundred subjects were studied retrospectively. A DXA (GE Lunar Prodigy) scan of the forearm was performed on each subject to measure the bone mineral density (BMD) value at the location of ultra-distal radius, and an X-ray digital image of the same forearm was taken on the same day. The values of trabecular bone score along the direction perpendicular to the forearm, TBSx, and along the direction parallel to the forearm, TBSy, were calculated respectively. The statistics of TBSx and TBSy were calculated, and the anisotropy of the trabecular bone, which was defined as the ratio of TBSy to TBSx and changed with subjects’ BMD and age, was reported and analyzed. Results: The results show that the correlation coefficient between TBSx and TBSy was 0.72 (p BMD and age was reported. The results showed that decreased trabecular bone anisotropy was associated with deceased BMD and increased age in the subject group. Conclusions: This study shows that decreased trabecular bone anisotropy was associated with decreased BMD and increased age.

Imaging Analysis of Trabecular Bone Texture Based on the Initial Slope of Variogram of Ultra-Distal Radius Digital X-Ray Imaging: Effects on Bone Mineral Density and Age

Background: When applied to trabecular bone X-ray images, a method for analyzing trabecular bone texture based on the initial slope of variogram (ISV) was used to assess the trabecular bone health. Methodology: Data from more than two hundred subjects were retrospectively studied. For each subject, a DXA (GE Lunar Prodigy) scan of the forearm was performed, and bone mineral density (BMD) value was measured at the location of ultra-distal radius, X-ray digital image of the same forearm was taken on the same day, and ISV value over the same location of ultra-distal radius was calculated. Pearson’s correlation coefficients were calculated to examine the correlation between BMD and ISV of the trabecular bones located at the same ultra-distal radius. ISV values changed with subjects’ age were also reported. Results: The results show that ISV value was highly correlated with the DXA-measured BMD of the same trabecular bone located at the ultra-distal radius. The correlation coefficient between ISV and BMD with the 95% confident was 0.79 ± 0.09. They also demonstrated that the age-related changes in trabecular bone health and differentiated age patterns in males and females, respectively. The results showed that the decrease in BMD was accompanied by a decrease in the initial slope of variogram (ISV). Conclusions: This study suggests that ISV might be used to quantitatively evaluate trabecular health for osteoporosis and bone disease diagnosis.

A cadaveric breast cancer tissue phantom for phase-contrast X-ray imaging applications

Background:As mammography X-ray imaging technologies advance and provide elevated contrast in soft tissues,a need has developed for reliable imaging phantoms for use in system design and component calibration.In advanced imaging modalities such as refraction-based methods,it is critical that developed phantoms capture the biological details seen in clinical precancerous and cancerous cases while minimizing artifacts that may be caused due to phantom production.This work presents the fabrication of a breast tissue imaging phantom from cadaveric breast tissue suitable for use in both transmission and refraction-enhanced imaging systems.Methods:Human cancer cell tumors were grown orthotopically in nude athymic mice and implanted into the fixed tissue while maintaining the native tumor/adipose tissue interface.Results:The resulting human–murine tissue hybrid phantom was mounted on a clear acrylic housing for absorption and refraction X-ray imaging.Digital breast tomosynthesis was also performed.Conclusion:Both attenuation-based imaging and refraction-based imaging of the phantom are presented to confirm the suitability of this phantom's use in both imaging modalities.

Rapid digitalization and panoramic evaluation of weld X-ray film

The computer evaluation of weld X-ray film is an attractive technique for weld seam NDT （ nondestructive testing）. To achieve this target, digitalization of film is the first step and automatic defect identification is another key technique. In this paper, a weld X-ray film digitalizing system has been established with linear array CCD and highlight LED light source. Its space resolution can reach 0. 04 mm/pixel and scanning speed can reach 100 mm/s for an industrial film. The transfer function curves of the system have been measured and the results indicate that its image gray resolution can reach 88 G/D at 4. 5D, and its dynamic range can be wider than 2. OD. In order to facilitate the evaluation of large welded structure, a panoramic evaluation algorithm is developed also. The algorithm includes image matching, image fusion and panoramic evaluation of the long linked film image.

Research on Influence of Electromagnetic Interference on X-Ray Digital Detection

X-ray digital imaging technology has found wide application owing to its advantages of real-time, visualization and rapid imaging. In substations the substantial electromagnetic interference has some influence on the live detection by the X-ray digital imaging technology, hindering the promotion of the technology in the detection of electric equipment. Based on a large number of field tests, the author carded out a series of researches on electromagnetic interference protection measures, image de-noising, and image enhancement algorithms.

An Improved Neural Network Method for Forearm Bone Imaging Segmentation

In this paper, we propose several improved neural networks and training strategy using data augmentation to segment human radius accurately and efficiently. This method can provide pixel-level segmentation accuracy through the low-level features of the neural network, and automatically distinguish the classification of radius. The versatility and applicability can be effectively improved by learning and training digital X-ray images obtained from digital X-ray imaging systems of different manufacturers.

3D-DSA与Dyna-CT在颅内支架置入术中的临床应用研究

目的探讨三维DSA血管成像(3D-DSA)及数字平板造影机的C臂旋转并断层重建技术(DynaCT)在颅内支架置入术患者中的临床应用。方法选择2019年1月-2020年6月厦门大学附属中山医院收治92例颅内动脉狭窄患者,所有患者均行颅内支架置入术治疗,分为对照组(n=38例)和观察组(n=54例)。对照组采用3D-DSA引导,观察组采用DynaCT引导,术后进行12个月门诊随访,比较两组改良Rankin量表(mRS)评分、手术成功率、并发症、支架再狭窄及斑块检出率。结果观察组术后4个月、8个月及12个月mRS评分、支架成形术耗时低于对照组(P<0.05);观察组Dyna-CT的术前规划、观察到支架表面图像与术中所见吻合,手术成功率为83.33%,高于对照组63.16%(P<0.05);两组围术期并发症发生率无统计意义(P>0.05);观察组手术后进行12个月门诊随访,患者支架再狭窄、血管狭窄部位斑块检出率低于对照组(P<0.05)。结论DynaCT用于颅内支架置入术中能改善患者症状,缩短支架成形术耗时,有助于提高手术成功率,未增加并发症发生率,能降低血管狭窄部位斑块检出率,值得推广应用。

Three-dimensional finite element simulation and reconstruction of jointed rock models using CT scanning and photogrammetry

The geometry of joints has a significant influence on the mechanical properties of rocks.To simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory experiments and numerical simulations.In this study,the computerized tomography (CT) scanning and photogrammetry were employed to obtain the internal and surface joint structures of a limestone sample,respectively.To describe the joint geometry,the edge detection algorithms and a three-dimensional (3D) matrix mapping method were applied to reconstruct CT-based and photogrammetry-based jointed rock models.For comparison tests,the numerical uniaxial compression tests were conducted on an intact rock sample and a sample with a joint simplified to a plane using the parallel computing method.The results indicate that the mechanical characteristics and failure process of jointed rocks are significantly affected by the geometry of joints.The presence of joints reduces the uniaxial compressive strength (UCS),elastic modulus,and released acoustic emission (AE) energy of rocks by 37%–67%,21%–24%,and 52%–90%,respectively.Compared to the simplified joint sample,the proposed photogrammetry-based numerical model makes the most of the limited geometry information of joints.The UCS,accumulative released AE energy,and elastic modulus of the photogrammetry-based sample were found to be very close to those of the CT-based sample.The UCS value of the simplified joint sample (i.e.38.5 MPa) is much lower than that of the CT-based sample (i.e.72.3 MPa).Additionally,the accumulative released AE energy observed in the simplified joint sample is 3.899 times lower than that observed in the CT-based sample.CT scanning provides a reliable means to visualize the joints in rocks,which can be used to verify the reliability of photogrammetry techniques.The application of the photogrammetry-based sample enables detailed analysis for estimating the mechanical properties of jointed rocks.

Microstructural Characteristics of Asphalt Concrete with Different Gradations by X-ray CT

The main objective of this paper is to evaluate the effects of asphalt concrete types on the microstructural characteristics at high-temperature. Suspend-dense structure and Skeleton-dense structure were selected to investigate the deformation of pavement at meso-scale. The internal microstructures of typical asphalt concretes, AC, SUP and SMA, were scanned by X-ray CT device, and microstructural changes before and after high-temperature damage were researched by digital image processing. Adaptive threshold segmentation algorithm（ATSA） based on image radius was developed and utilized to obtain the binary images of aggregates, air-voids and asphalt mastic. Then the shape and distribution of air-voids and aggregates were analyzed. The results show that the ATSA can distinguish the target and background effectively. Gradation and coarse aggregate size of asphalt mixtures have an obvious influence on the distribution of air-voids. The movements of aggregate particles are complex and aggregates with elliptic sharp show great rotation. The effect of gradation on microstructure during high-temperature damage promotes the research about the failure mechanism of asphalt concrete pavement.

数字图像相关法在汽车门饰板低温气囊点爆试验中的应用

采用数字图像相关法对汽车门饰板在低温气囊点爆试验时的变形情况进行测试,绘制了材料在不同应变速率下的应变曲线,建立了气囊点爆时零件的位移及应变的实际图像与仿真分析结果的关联,并输出与仿真网格结点相对应的数据。结果表明:非接触式数字图像相关法既可以获得汽车门饰板材料不同应变速率下的应变曲线,又可以获得气囊点爆时高速碰撞产生的三维变形云图及数据。按照仿真网格要求划分云图,并且对齐点爆时间和坐标,输出的云图数据能够与仿真分析结果的数值进行逐点比对,可以清晰地了解仿真分析结果与实际试验结果的误差,为进一步优化仿真模型提供数据支持。

3D anisotropy in shear failure of a typical shale

It is inadequate to study the shear failure anisotropy of shale in only 2D space.Aiming at a 3D analysis,a series of direct shear tests was conducted on Longmaxi shale with three typical bedding orientations:arrester,divider and short-transverse orientations.During testing,acoustic emission(AE)and digital image correlation(DIC)techniques were simultaneously employed to monitor failure development,after testing,X-ray computed tomography(CT)scanning was adopted to acquire and reconstruct the fractures inside typical ruptured samples for more detailed analysis.The results indicated that the shear strength parameters exhibited 3D anisotropies and those of the arrester sample did not have equivalent shear strength parameters to the shale matrix.The maximum(minimum)shear strength and cohesion were obtained with the divider(short-transverse)orientation,and the internal friction angle reached its maximum(minimum)with the divider(arrester)orientation.Combining the AE,DIC and CT techniques,four characteristic stress levels that can capture the progressive shear failure process of shale rocks were identified,and the onset and accelerated development of shear damage-induced dilation were observed at the crack initiation and coalesce stress thresholds,respectively.During the crack coalescence stage,the dominated microcracking mechanism transferred from tensile-mode to shear-mode.For the arrester and divider orientations,more tensile-mode AE events were generated due to the microcracking along the vertical beddings.Compared with the divider samples,a more complex fracture network with a larger fracture area and volume was obtained in the arrester samples,whose strengths were smaller.

X射线平板探测器数字成像及其图像校准

为了提高X射线数字成像系统的图像质量 ,以基于平板探测器的X射线数字照相系统为研究对象 ,介绍了平板探测器自身影响图像质量的 4大因素 :随机噪声 ,偏置误差 ,像元响应不一致性和瑕疵像元等 ,分析了这些因素的成因及其对图像质量的影响 ,提出了相应的减小和消除这些影响的图像校准方法 .实验结果表明 :运用这些图像校准方法 ,可以有效地去除上述因素对图像质量的影响 ,显著提高平板探测器输出图像的质量 。

平板探测器X射线数字成像质量

以提高图像质量为目的,对平板探测器数字成像系统进行全面分析,探讨其成像质量的影响因素,认为几何结构和噪声是影响成像质量的主要因素,并建立相应的数学模型.以此为基础,采用约束最小二乘方滤波器对降质后的图像进行滤波复原.仿真结果表明,所建立的数学模型是有效的,复原后图像的质量一定程度上得到了改善.

西门子Artis zee系列血管造影系统优势分析

目的:对西门子Artis zee系列数字减影血管造影(DSA)系统的特点进行分析,找出其特有的优势供临床医务工作者诊疗参考。方法:通过学习该系统的维修手册,参加该机器的维修工程师培训,并通过实际医疗操作对比而获得对该系统的整体认识。结果:通过学习和临床对比,掌握该系统在系统设计、操作界面、安全防护及图像处理等方面具有一定的优势,可以促进临床心血管疾病的诊疗水平。结论:西门子Artiszee系列DSA系统在临床诊疗中具有显著的技术优势,可有效地应用于心血管造影的诊断和治疗中。

数字射线面阵探测器校正的优化技术

数字射线探测器的校正效果很大程度上影响到射线检测的图像质量,为避免图像质量出现不可控或严重劣化问题,对数字射线面阵探测器的校正及其优化技术进行了研究。分析了射线探测器的校正程序、射线探测器的信号转换过程,在此基础上,改变射线能量、射线强度,进行探测器的校正试验。实验结果表明:经有效校正处理后,探测器各像元间的不一致情况明显得到抑制,图像灰度值达到较均匀状态。探测器校正时,接收的射线强度高,可获得更高的图像信噪比,从而有利于提高图像质量。探测器校正时使射线能量与射线检测时的能量相同,可在射线检测时获得良好校正输出。通过试验分析可知,优化数字射线探测器校正方法的关键在于选取适合的校正因子;而对于图像质量已劣化的数字射线探测器输出,仍可采取措施使输出的图像质量得到改善,即先将劣化图像还原为特定射线辐照下探测器的响应,然后使用合适的校正因子对还原后的探测器响应进行校正。

X射线DR技术在铝合金铸件检测中的应用

本文简要介绍了DirectDigit Radiography(DR)X射线直接数字化成像检测技术及DR检测的基本原理,并从工艺应用角度对数字成像的表征参数如空间分辨力、像素、密度分辨力、密度分辨力与空间分辨力的关系、信噪比(SNR)、量子探测效率(DQE)等进行了工艺性解释说明;同时,该文还结合一套真实在用的典型面板探测器DR成像检测系统的工艺实践,总结出铝合金铸件的X射线DR检测特征和铝合金铸件常见缺陷的DR图像特征,给出了铝合金铸件典型缺陷DR图像,对同类检测项目具有重要的参考意义。

时变热辐射环境下高温合金蜂窝板三维热变形测量

轻质、高强和隔热性能优良的蜂窝合金板结构已广泛用于航空航天领域,其在模拟瞬态气动热环境下的热变形是高速飞行器热防护结构设计的重要参数之一.首先,用自行研制的红外辐射瞬态气动热实验模拟系统模拟与其服役环境类似的时变热辐射环境,用新型"主动成像"三维数字图像相关(3D-DIC)测量方法对高温合金蜂窝板结构试件在时变热辐射环境下不同时刻的三维热变形进行了测量.其次,为保证三维数字图像相关测量方法能有效实施,提出一种制作稳定的大面积高温散斑新方法,该方法制作的高温散斑能在整个实验过程中保持稳定,可作为高温变形的有效载体.最后,用Hoff等效刚度理论计算高温合金蜂窝板在稳态时的最大翘曲位移.研究结果表明:210 mm×210 mm的高温合金蜂窝板在单侧面辐射加热条件下其面内变形为均匀热变形,而离面变形为轴对称的翘曲变形,在900℃时其最大离面翘曲位移约为1.6 mm;Hoff等效刚度理论计算结果与实验结果相吻合.

2种平板探测器在床旁摄影的临床应用对比研究

目的 :探讨数字化X线摄影(digital radiographpy,DR)无线平板探测器在床旁检查中的临床应用价值。方法 :回顾性对比分析由无线平板探测器和有线平板探测器分别采集的175张床旁胸部正位片,依照X线的照片评分标准利用双盲法对X线照片进行质量分类,并统计其各自所占的比例。结果:2种探测器分别采集的175张床旁胸部正位片中,使用无线平板探测器采集的图像甲级片率为93.1%,乙级片率为6.9%,无丙级片及废片;使用有线平板探测器采集的图像甲级片率为81.1%,乙级片率为15.4%,丙级片率为3.5%,无废片。结论:DR无线平板探测器所采集的图像能提供更加优质的影像资料,而且操作更加方便,更有利于提高床旁检查的图像质量。

数字平板技术成就了能量减影

通过介绍DSA中双能量减影的基本原理和发展过程,论述由于数字平板式X射线诊断设备(DR)的技术发展,使能量减影获得了新生,真正开始在临床中应用。

土工平面应变仪压力室的改进

现有的平面应变试验仪都不能很好地解决接触摩擦的问题,试验中土样与约束面板之间存在较大的摩擦力影响变形测量的准确性。在总结平面应变仪发展历程的基础上,根据加载方式将平面应变仪分为4类,分析了现有的平面应变试验仪的特点和存在的问题;介绍了一种改进的平面应变仪的压力室。改进后的压力室在前、后约束面板与土样之间分别增设一层厚约3 mm的密封水膜。在试验过程中,包裹土样的橡皮膜与密封水膜的硅胶膜紧密贴合而不直接与面板贴合,可以消除土样与面板之间的摩擦。同时,新型的压力室还可应用于土样变形数字图像测量系统,实时测量土样表面的变形分布,可以比较精确地测量土样的表面变形、剪切带的形成过程及特征。分别使用改进的压力室和未改进的压力室对福建标准砂进行平面应变试验,前者测得的应力-应变关系曲线的峰值比后者低约60%。制备相同干密度的土样分别进行不同围压条件下的三轴试验和平面应变试验测取土样的抗剪强度,使用改进压力室得到的抗剪强度参数与三轴试验测得的结果很接近,而使用未改进的压力室测得结果则明显不合理。