Augment low-field intra-operative MRI with preoperative MRI using a hybrid non-rigid registration method

Background

Preoperatively acquired diffusion tensor image (DTI) and blood oxygen level dependent (BOLD) have been proved to be effective in providing more anatomical and functional information; however, the brain deformation induced by brain shift and tumor resection severely impairs the correspondence between the image space and the patient space in image-guided neurosurgery.

Method

To address the brain deformation, we developed a hybrid non-rigid registration method to register high-field preoperative MRI with low-field intra-operative MRI in order to recover the deformation induced by brain shift and tumor resection. The registered DTI and BOLD are fused with low-field intra-operative MRI for image-guided neurosurgery.

Results

The proposed hybrid registration method was evaluated by comparing the landmarks predicted by the hybrid registration method with the landmarks identified in the low-field intra-operative MRI for 10 patients. The prediction error of the hybrid method is 1.92 ± 0.54 mm, and the compensation accuracy is 74.3 ± 5.0%. Compared to the landmarks far from the resection region, those near the resection region demonstrated a higher compensation accuracy (P-value = .003) although these landmarks had larger initial displacements.

Conclusions

The proposed hybrid registration method is able to bring preoperatively acquired BOLD and DTI into the operating room and compensate for the deformation to augment low-field intra-operative MRI with rich anatomical and functional information.     

The thin plate spline robust point matching (TPS-RPM) algorithm: A revisit

This paper reviews the TPS-RPM algorithm (Chui and Rangarajan, 2003) for robustly registering two sets of points and demonstrates from a theoretical point of view its inherent limited performance when outliers are present in both point sets simultaneously. A double-sided outlier handling approach is proposed to overcome this limitation with a rigorous mathematical proof as the underlying theoretical support. This double-sided outlier handling approach is proved to be equivalent to the original formulation of the point matching problem. For a practical application, we also extend the TPS-RPM algorithms to non-rigid image registration by registering two sets of sparse features extracted from images. The intensity information of the extracted features are incorporated into feature matching in order to reduce the impact from outliers. Our experiments demonstrate the double-sided outlier handling approach and the efficiency of intensity information in assisting outlier detection.     

基于OpenGL的快速原形制造系统仿真

随着计算机技术的发展,可视化仿真和快速原形制造RPM已经成为CAD/CAM仿真领域的热点.文中介绍了RPM可视化仿真系统的总体结构和软件设计思想,为了实现数控机床加工零件产品的快速原形制造系统,提出了一种基于AutoCADRl4、VisualC 6.0和OpenGL语言的RPM技术实现方案.该方案利用VisualC 6.0作为系统开发平台,使用目前通用的3D图形API标准,可以方便地将AutoCADRl4输出的STL文件利用OpenGL进行三维真实感显示,并可以根据需要实现各种视图变换操作.最后给出了一个仿真结果,验证了该系统的性能.     

A modernized and versatile startup reactivity measuring system installed at NPP Paks and its application for subcritical systems

In 2004 the Hungarian Paks NPP completed a project for upgrading the reactivity measuring system applied during reactor startup experiments. Almost all components of the previous system were replaced, only ex-core ionisation chambers remained unaltered. New hardware and software components were introduced for neutron flux signal handling, for data acquisition, as well as for measurement evaluation and data presentation. High-precision picoamper meters were installed at each reactor unit, current signals are handled by a portable signal processing unit. The system applies an accurate on-line reactivity calculation algorithm based on the point-kinetic model with six delayed neutron groups. Detailed off-line evaluation and analysis of startup measurements can be performed on the portable unit, as well.The paper describes the architecture, data acquisition modules, services and man–machine interface of the new system. Functions and results are illustrated with measured data recorded during a startup of Unit 3. In 2003 and 2004 the RMR was installed and tested at all Paks NPP units successfully and now it is in regular use during unit startups.The second part of the paper illustrates an extension of the new system to perform reactivity measurements using the well-known Rossi-α and Feynman-α statistical methods. The modified system was needed to estimate the reactivity of a subcritical system formed by damaged fuel assemblies stored at the fuel service pit of Paks Unit 2. Theoretical background of the applied algorithms is outlined, then results of validation tests and on site measurements are treated. The measurements have shown that the subcriticality of the damaged fuel was sufficiently deep if the high boron concentration in the fuel service pit was maintained.     

新型实用快速成型技术及其应用

叙述了快速成型技术的发展，介绍了几种典型的快速成型技术及原理，展望了快速成型技术的应用及前景．     

严寒荒漠地带大口径RPM管道的应用

RPM管道是采用高模量增强纤维和合成树脂及高质量的石英砂组合的一种复合材料管,具有寿命长、抗侵蚀性能高、适应地基变形能力好、便于运输和安装等优点.本文以北疆某供水工程倒虹吸应用大口径RPM管道为例,就工程管道选用、施工工艺和质量控制方面做了系统的介绍.工程实践证明,只要设计结构合理、质量控制措施到位,在特殊环境的大型工...     

缠绕夹砂玻璃钢管（RPM管）的成型工艺参数分析

本文简要介绍了缠绕夹砂玻璃钢管（ＲＰＭ管）的管壁结构型式，并对其成型工艺过程及其参数作了分析探讨。     

TC655在风扇速度控制中的应用

本文介绍了风扇速度控制器TC655芯片的主要特性、工作过程。并给出了它的应用电路和CPU程序设计流程图。     

Real-time air monitoring of occupational exposures to particulate matter among hairdressers in Maryland: A pilot study

Hairdressers are exposed to particulate matter (PM), a known air pollutant linked to adverse health effects. Still, studies on occupational PM exposures in hair salons are sparse. We characterized indoor air PM concentrations in three salons primarily serving an African/African American (AA) clientele, and three Dominican salons primarily serving a Latino clientele. We also assessed the performance of low-cost sensors (uRAD, Flow, AirVisual) by comparing them to high-end sensors (DustTrak) to conduct air monitoring in each salon over 3 days to quantify work shift concentrations of PM_2.5, respirable PM (RPM), and PM₁₀. We observed high spatial and temporal variability in 30-min time-weighted average (TWA) RPM concentrations (0.18–5518 μg/m³). Readings for the uRAD and AirVisual sensors were highly correlated with the DustTrak (R² = 0.90–0.99). RPM 8-hour TWAs ranged from 18 to 383 µg/m³ for AA salons, and 9–2115 µg/m³ for Dominican salons. Upper 95th percentiles of daily RPM exposures ranged from 439 to 2669 µg/m³. The overall range of 30-min TWA PM_2.5 and PM₁₀ concentrations was 0.13–5497 and 0.36-,541 μg/m³, respectively. Findings suggest that hairdressers could be overexposed to RPM during an 8-hour shift. Additional comprehensive monitoring studies are warranted to further characterize temporal and spatial variability of PM exposures in this understudied occupational population.     

快速原型技术现状与发展趋势研究

该文简要介绍了快速原型技术的原理、快速原型技术的特点,阐述了国内外现状及发展趋势。