An Approximate Cone Beam Reconstruction Algorithm for Gantry-Tilted CT Using Tangential Filtering

FDK algorithm is a well-known 3D (three-dimensional) approximate algorithm for CT (computed tomography) image reconstruction and is also known to suffer from considerable artifacts when the scanning cone angle is large. Recently, it has been improved by performing the ramp filtering along the tangential direction of the X-ray source helix for dealing with the large cone angle problem. In this paper, we present an FDK-type approximate reconstruction algorithm for gantry-tilted CT imaging. The proposed method improves the image reconstruction by filtering the projection data along a proper direction which is determined by CT parameters and gantry-tilted angle. As a result, the proposed algorithm for gantry-tilted CT reconstruction can provide more scanning flexibilities in clinical CT scanning and is efficient in computation. The performance of the proposed algorithm is evaluated with turbell clock phantom and thorax phantom and compared with FDK algorithm and a popular 2D (two-dimensional) approximate algorithm. The results show that the proposed algorithm can achieve better image quality for gantry-tilted CT image reconstruction

Angiotensin-converting enzyme insertion/deletion polymorphism and susceptibility to Kawasaki disease: a meta-analysis.

Background: The angiotensin-converting enzyme (ACE) I/D polymorphism has been reported to be associated with Kawasaki disease(KD) ,but studies to date present conflicting results. Objectives: The aim of this study is to derive a more precise estimation of the association between the ACE I/D polymorphism and KD risk. Methods: PubMed,EMBASE,CNKI and Wangfang databases were retrievaled to identify for relevant studies from inception to May 2017.Pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated using Stata 12.0 software. Results: A total of 6 case-control studies comprising 634 patients and 458 controls were included in the meta-analysis,and we found a significant association between the ACE I/D polymorphism and KD risk(D vs I:OR = 0.81, 95%CI = 0.31-2.11;DD vs II: OR = 1.03, 95%CI = 0.42-2.54; DI vs II: OR = 1.44, 95%CI = 1.09-1.90; dominant model: OR = 1.43, 95%CI = 1.11-1.85; recessive model: OR = 1.21, 95%CI = 0.44-3.29 ).When stratified by sample size>200, this polymorphism is associated with an increased the risk of KD. Conclusion: The I/D polymorphism in the ACE gene may be associated with susceptibility to KD

ModelScope-Agent: Building Your Customizable Agent System with Open-source Large Language Models

Large language models (LLMs) have recently demonstrated remarkable capabilities to comprehend human intentions, engage in reasoning, and design planning-like behavior. To further unleash the power of LLMs to accomplish complex tasks, there is a growing trend to build agent framework that equips LLMs, such as ChatGPT, with tool-use abilities to connect with massive external APIs. In this work, we introduce ModelScope-Agent, a general and customizable agent framework for real-world applications, based on open-source LLMs as controllers. It provides a user-friendly system library, with customizable engine design to support model training on multiple open-source LLMs, while also enabling seamless integration with both model APIs and common APIs in a unified way. To equip the LLMs with tool-use abilities, a comprehensive framework has been proposed spanning over tool-use data collection, tool retrieval, tool registration, memory control, customized model training, and evaluation for practical real-world applications. Finally, we showcase ModelScopeGPT, a real-world intelligent assistant of ModelScope Community based on the ModelScope-Agent framework, which is able to connect open-source LLMs with more than 1000 public AI models and localized community knowledge in ModelScope. The ModelScope-Agent library\footnote{https://github.com/modelscope/modelscope-agent} and online demo\footnote{https://modelscope.cn/studios/damo/ModelScopeGPT/summary} are now publicly available

An approximate cone beam reconstruction algorithm for gantry-tilted CT

Abstract not reproduced here by request of the publisher. The text is available from: http://dx.doi.org/10.1117/12.653121

Data correction for gantry-tilted local CT

The gantry-tilted helical cone-beam computed tomography (CT) has an inherent problem that the relative shift of the region of interest (ROI) blurs the reconstructed image. This problem becomes more serious in the gantry-tilted local CT imaging due to the nature of local scanning. This paper proposes a new method to improve the gantry-tilted local imaging by correcting the local scanning data. Computer simulations show that the proposed method can enhance the local imaging performance to a certain extent in terms of the image sharpening and artifacts reduction

A reconstruction algorithm for helical CT imaging on PI-planes

In this paper, a Feldkamp type approximate reconstruction algorithm is presented for helical cone-beam Computed Tomography. To effectively suppress artifacts due to large cone angle scanning, it is proposed to reconstruct the object pointwisely on unique customized tilted PI-planes which are close to the data collecting helices of the corresponding points. Such a reconstruction scheme can considerably suppress the artifacts in the cone-angle scanning. Computer simulations show that the proposed algorithm can provide improved imaging performance compared with the existing approximate cone-beam reconstruction algorithms

An extended half-scan Feldkamp-type CT reconstruction

Abstract not reproduced here by request of the publisher. The text is available from: http://dx.doi.org/10.1117/12.653126

A new scheme and reconstruction algorithm for dual source circular CT

Circular cone beam scanning has been a most popular scheme for computed tomography (CT) imaging, which is simple and can achieve symmetric projection data of the interested object. Many algorithms have been developed for circular cone beam CT. Many of these are FDK type algorithms, which can achieve good reconstruction quality when cone angle is small but may cause image deformation and density reduction at off plane when the cone angle is large. With the recently introduced dual source circular cone beam CT, we can deal with this problem under a new dual source geometry. In this paper, we propose a novel reconstruction scheme dual source circular cone beam CT by placing X-ray sources on two circular planes perpendicular to the rotating axis. We propose a reconstruction algorithm for this scanning scheme and evaluate the scanning scheme and the reconstruction algorithm with a 3D Shepp Logan phantom and a disk phantom. Simulation results show that the proposed method can provide improved reconstruction image quality for both in plane and off plane of the object

Topside Ionospheric Structures Determined via Automatically Detected DEMETER Ion Perturbations during a Geomagnetically Quiet Period

In this study, 117,718 ionospheric perturbations, with a space size (t) of 20–300 s but no amplitude (A) limit, were automatically globally searched via software utilizing ion density data measured by the DEMETER satellite for over 6 years. The influence of geomagnetic storms on the ionosphere was first examined. The results demonstrated that storms can globally enhance positive ionospheric irregularities but rarely induce plasma variations of more than 100%. The probability of PERs with a space size falling in 200–300 s (1400–2100 km if a satellite velocity of 7 km/s is considered) occurring in a geomagnetically perturbed period shows more significance than that in a quiet period. Second, statistical work was performed on ion PERs to check their dependence on local time, and it was shown that 24.8% of the perturbations appeared during the daytime (10:30 LT) and 75.2% appeared during the nighttime (22:30 LT). Ionospheric fluctuations with an absolute amplitude of A A A > 100% mostly occurred at night and negative ones with A t = 120 s, and the occurrence probabilities of day PERs were always higher than that of nighttime ones before this point, while this trend was contrary after this point. Finally, distributions of PERs according to different ranges of amplitude and space scale were characterized by typical seasonal variations either in the daytime or nighttime. EIA only exists in the dayside equinox and winter, occupying two low-latitude crests with a lower Np in both hemispheres. Large WSAs appear within all periods, except for dayside summer, and are full of PERs with an enhanced amplitude, especially on winter nights. The WN-like structure is obvious during all seasons, showing large-scale space. On the other hand, several magnetically anomalous zones of planetary-scale non-dipole fields, such as the SAMA, Northern Africa anomaly, and so on, were also successfully detected by extreme negative ion perturbations during this time