Accuracy of 2D CT-Based Measurements of Rotational Alignment of the Femoral Component for Total Knee Arthroplasty

PurposeWe aimed to investigate the accuracy of two-dimensional computed tomography (2D-CT)-based methods for measuring rotational alignment of the femoral component during total knee arthroplasty in comparison to reference values for three-dimensional (3D) reconstruction.Materials and MethodsWe selected the “most protruding transepicondylar axis section,” “most protruding posterior condylar line section,” and “distal femoral cut section” on 2D-CT images for 100 knees. We investigated posterior condylar angle (PCA) and condylar twist angle (CTA) values using three different methods on 2D-CT and compared to these values to those obtained using a 3D model.ResultsThe mean PCA and CTA values were 2.8° and 7.0° on the 3D model and 2.0° to 2.1° and 5.9° to 6.0° on 2D-CT, respectively. Errors in PCA and CTA measurement included internal rotation of 0.8° and 1.1° with the 1-plane and 2-plane methods and 0.9° and 1.0° with the assumed resection method, respectively.ConclusionMean errors in PCA and CTA values measured using three different methods on 2D-CT were not significantly different. However, PCA and CTA values measured on 2D-CT were approximately 1° smaller than their 3D values. Thus, we suggest that adding 1° to the mean PCA and CTA values obtained from a single plane of 2D-CT would provide values similar to those obtained from 3D reconstruction.     

Patient-Specific Three-Dimensional Composite Bone Models for Teaching and Operation Planning

Background: Orthopedic trauma care relies on two-dimensional radiograms both before and during the operation. Understanding the three-dimensional nature of complex fractures on plain radiograms is challenging. Modern fluoroscopes can acquire three-dimensional volume datasets even during an operation, but the device limitations constrain the acquired volume to a cube of only 12-cm edge. However, viewing the surrounding intact structures is important to comprehend the fracture in its context. We suggest merging a fluoroscope’s volume scan into a generic bone model to form a composite full-length 3D bone model. Methods: Materials consisted of one cadaver bone and 20 three-dimensional surface models of human femora. Radiograms and computed tomography scans were taken before and after applying a controlled fracture to the bone. A 3D scan of the fracture was acquired using a mobile fluoroscope (Siemens Siremobil). The fracture was fitted into the generic bone models by rigid registration using a modified least-squares algorithm. Registration precision was determined and a clinical appraisal of the composite models obtained. Results: Twenty composite bone models were generated. Average registration precision was 2.0 mm (range 1.6 to 2.6). Average processing time on a laptop computer was 35 s (range 20 to 55). Comparing synthesized radiograms with the actual radiograms of the fractured bone yielded clinically satisfactory results. Conclusion: A three-dimensional full-length representation of a fractured bone can reliably be synthesized from a short scan of the patient’s fracture and a generic bone model. This patient-specific model can subsequently be used for teaching, surgical operation planning, and intraoperative visualization purposes.     

真空定位袋的质量保证与质量控制

目的：探讨放疗中真粉固定袋的质量保证和质量控制的内容与和方法。方法：（1）把真空袋抽成真空，分别使真空袋厚度为1cm、2cm、3cm…、10cm不等。放在治疗床上，调整各项参数，用能量为6MV和15MV的x线分别照射，然后拿掉真空袋，条件同上照射。计算出真窄袋的穿射因子。（2）真空袋对体表剂量的影响，首先测出一组不同厚度时的开放野的数值。再将4种不同的真空垫平放在有机玻璃模体上，再测出一组读数，求出体表剂量的增量。结果：（1）真空袋的厚度不同，穿射因子也不同。射线能量不同，穿射因子也有差异。（2）使用真空袋提高了皮肤表面的剂量。结论：对真空袋进行质量保证和质量控制，以保证放射治疗定位和剂量计算的精度。对新买的真空袋，医院应该对其检测后再使用。     

骨功能适应性重建模型及数值模拟

骨骼会受到力学因素的影响和调控,发生骨功能适应性重建。建立模拟骨重建的数值模型,定量地研究骨重建过程,有着重要的临床应用价值。目前,骨功能适应性重建模型可分为两大类：力学模型和生理模型。对这两类重建模型的原理、算法和应用等做详细论述。力学模型通过假设力学环境与骨结构之间的函数关系来预测骨重建,但不考虑其真实的生物学过程。基于不同的重建激励主要有两种力学模型：骨力学稳态模型和骨损伤修复模型。生理模型则试图从微观层次阐明骨重建的力学-生物学机制,骨重建是由破骨细胞、成骨细胞等各种骨组织细胞完成,有以基本多细胞单位的形式作用或细胞独立分开作用两种观点。这些重建模型结合有限元法应用在许多有关骨重建问题的数值计算中。通过比较分析多个数值应用的模拟结果,还讨论了重建控制方程中各参数值的设置对重建结果的影响。     

基于VTK的医学图像网格化建模系统开发

开发了一套基于VTK的集医学图像处理、三维重建、有限元网格生成功能为一体的软件系统,实现了从医学图像到有限元网格解剖真实的几何建模.系统通过读取医学切片图像,在图像预处理、分割、表面重建、平滑与简化后生成解剖真实的几何模型和有限元网格.系统可输出CAD、RP/RM、有限元体网格文件,为基于医学图像的生物力学仿真、基于数值模拟的外科手术规划、快速成型与制造服务.     

放射治疗网络系统质量保证体系的设计和应用

目的：设计和应用放射治疗网络系统的质量保证体系。方法：放疗网络采用局域网、客户机服务器模式．基于PACS开发，将放疗过程中的相关设备通过网络联系存一起一患者的资料包括治疗资料和影像学资料统一在一个完整的数据库里。结果：质量控制体系包括网络安全体系、不同用户的权限设定、MU计算的质量保证、TPS计算的MU的质量保证、数据传输和数据备份的质量保证五个部分。结论：质量保证体系的应用能避免放疗网络系统的产生差错．是放疗网络系统的重要组成部分。     

Development and Validation of CT-Based Radiomics Signature for Overall Survival Prediction in Multi-organ Cancer

Journal of Digital Imaging - The malignant tumors in nature share some common morphological characteristics. Radiomics is not only images but also data; we think that a probability exists in a set...     

Model-Based Sensorimotor Integration for Multi-Joint Control: Development of a Virtual Arm Model

An integrated, sensorimotor virtual arm (VA) model has been developed and validated for simulation studies of control of human arm movements. Realistic anatomical features of shoulder, elbow and forearm joints were captured with a graphic modeling environment, SIMM. The model included 15 musculotendon elements acting at the shoulder, elbow and forearm. Muscle actions on joints were evaluated by SIMM generated moment arms that were matched to experimentally measured profiles. The Virtual Muscle^TM (VM) model contained appropriate admixture of slow and fast twitch fibers with realistic physiological properties for force production. A realistic spindle model was embedded in each VM with inputs of fascicle length, gamma static (γ_stat) and dynamic (γ_dyn) controls and outputs of primary (I_a) and secondary (II) afferents. A piecewise linear model of Golgi Tendon Organ (GTO) represented the ensemble sampling (I_b) of the total muscle force at the tendon. All model components were integrated into a Simulink block using a special software tool. The complete VA model was validated with open-loop simulation at discrete hand positions within the full range of α and γ drives to extrafusal and intrafusal muscle fibers. The model behaviors were consistent with a wide variety of physiological phenomena. Spindle afferents were effectively modulated by fusimotor drives and hand positions of the arm. These simulations validated the VA model as a computational tool for studying arm movement control. The VA model is available to researchers at website .     

浅探影响虚拟参考咨询服务质量的因素

服务是参考咨询的生命力。通过分析虚拟参考咨询服务的特点和服务方式,探讨了影响虚拟参考咨询服务质量的因素,指出提高虚拟参考咨询服务能力的基本对策。     

Quality Control Limits for Dilution and Disk Diffusion Susceptibility Tests of Trovafloxacin against Eight Quality Control Strains

A 10-laboratory collaborative effort was designed to generate data to propose quality control limits for susceptibility tests of trovafloxacin. Broth microdilution, agar dilution, and disk diffusion tests were evaluated with eight different control strains. All tests were reproducible, and control limits are proposed.     

胰岛素,C肽RIA检测中的室内质量控制

本文介绍了胰岛素、Ｃ肽ＲＩＡ检测中的三种室内质控方法，即质控血清监测法，两样本Ｙｏｕｄｅｎ图监测法和标准曲线参数监测法，并对其结果做了初步分析。三种室内质控方法的应用，保证了每一批测定结果的准确可靠，提高了不同批实验结果的可比性。本文还对胰岛素、Ｃ肽ＲＩＡ检测中使用的试剂盒进行了方法评价。胰岛素、Ｃ肽测定的批内ＣＶ分别为５．４８％和９．９８％；批间ＣＶ分别为１０．５４％和１４．５６％；平均回收率分     

免疫检验的质量控制分析

目的 对临床免疫检验质量控制措施进行分析.方法 从标本的采集、仪器设备的使用以及可能影响检验结果几方面分别进行论述.结果 影响临床免疫检验结果的因素有内源性因素和外源性因素,可以从样本选择、样本浓度以及质控方法几方面加强临床免疫结果的控制.结论 免疫检验前阶段的质量控制是容易被忽视的环节,需要引起足够的重视,才能确保检验结果的准确性和可靠性.     

Numerical Study of High-Frequency Oscillatory Air Flow and Convective Mixing in a CT-Based Human Airway Model

High-frequency oscillatory ventilation (HFOV) is considered an efficient and safe respiratory technique to ventilate neonates and patients with acute respiratory distress syndrome. HFOV has very different characteristics from normal breathing physiology, with a much smaller tidal volume and a higher breathing frequency. In this study, the high-frequency oscillatory flow is studied using a computational fluid dynamics analysis in three different geometrical models with increasing complexity: a straight tube, a single-bifurcation tube model, and a computed tomography (CT)-based human airway model of up to seven generations. We aim to understand the counter-flow phenomenon at flow reversal and its role in convective mixing in these models using sinusoidal waveforms of different frequencies and Reynolds (Re) numbers. Mixing is quantified by the stretch rate analysis. In the straight-tube model, coaxial counter flow with opposing fluid streams is formed around flow reversal, agreeing with an analytical Womersley solution. However, counter flow yields no net convective mixing at end cycle. In the single-bifurcation model, counter flow at high Re is intervened with secondary vortices in the parent (child) branch at end expiration (inspiration), resulting in an irreversible mixing process. For the CT-based airway model three cases are considered, consisting of the normal breathing case, the high-frequency-normal-Re (HFNR) case, and the HFOV case. The counter-flow structure is more evident in the HFNR case than the HFOV case. The instantaneous and time-averaged stretch rates at the end of two breathing cycles and in the vicinity of flow reversal are computed. It is found that counter flow contributes about 20% to mixing in HFOV.     

采用Evolution CDR补偿重建技术提高骨断层图像质量方法学研究

目的 应用Evolution CDR补偿技术对骨断层图像质量的改善进行评价.方法 随机选择32例骨断层显像,分别进行全时采集OSEM迭代处理,1/2时采集OSEM处理以及1/2时采集Evolution处理和全时采集Evolution处理.通过盲法读片,对三种不同图像采集处理技术获得图像进行图像质量评分.结果 1/2时采集Evolution重建图像质量与全时采集OSEM重建图像质量相当;而全时采集Evolution重建的图像质量明显优于全时采集OSEM重建.结论 Evolution重建技术通过对CDR补偿,能降低图像噪声,明显改善图像质量,或者在得到与全时采集OSEM迭代重建相当的图像质量的情况下,可以大大降低采集时间.     

股骨头缺血性坏死骨瓣移植过程的有限元模拟

基于临床上的一例股骨头三期缺血性坏死患者的单侧CT图像数据，建立了股骨近端的三维有限元模型，包括：正常模型、坏死模型和修复模型。并基于医学OF图像数据，分别对三种有限元模型赋予材料性质。最后应用有限元软件，对股骨头缺血性坏死骨瓣移植手术过程进行了数值模拟。分析结果表明，切除掉坏死区域后，股骨头近端的位移及应力值均增加较大，而采用骨瓣移植手术，可以有效地减少股骨近端的位移及应力值，使其更接近正常状态。说明了该手术方法安全可靠并行之有效。