scholarly journals A new method for CT dose estimation by determining patient water equivalent diameter from localizer radiographs: Geometric transformation and calibration methods using readily available phantoms

2018 ◽  
Vol 45 (7) ◽  
pp. 3371-3378 ◽  
Author(s):  
Da Zhang ◽  
Georgeta Mihai ◽  
Larry G. Barbaras ◽  
Olga R. Brook ◽  
Matthew R. Palmer
Keyword(s):  
New Method ◽  
Geometric Transformation ◽  
Equivalent Diameter ◽  
Dose Estimation ◽  
Ct Dose ◽  
Calibration Methods

scholarly journals Extraction and Visualization of Ocular Blood Vessels in 3D Medical Images Based on Geometric Transformation Algorithm

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Zhike Zhang ◽  
Shuixin Zhang ◽  
Hongyu Feng
Keyword(s):  
Blood Vessels ◽  
Input Signal ◽  
Medical Images ◽  
Vessel Segmentation ◽  
New Method ◽  
Geometric Transformation ◽  
High Contrast ◽  
Low Contrast ◽  
Resonance Response ◽  
Local Image

Data extraction and visualization of 3D medical images of ocular blood vessels are performed by geometric transformation algorithm, which first performs random resonance response in a global sense to achieve detection of high-contrast coarse blood vessels and then redefines the input signal as a local image shielding the global detection result to achieve enhanced detection of low-contrast microfine vessels and complete multilevel random resonance segmentation detection. Finally, a random resonance detection method for fundus vessels based on scale decomposition is proposed, in which the images are scale decomposed, the high-frequency signals containing detailed information are randomly resonantly enhanced to achieve microfine vessel segmentation detection, and the final vessel segmentation detection results are obtained after fusing the low-frequency image signals. The optimal stochastic resonance response of the nonlinear model of neurons in the global sense is obtained to detect the high-grade intensity signal; then, the input signal is defined as a local image with high-contrast blood vessels removed, and the parameters are optimized before the detection of the low-grade intensity signal. Finally, the multilevel random resonance response is fused to obtain the segmentation results of the fundus retinal vessels. The sensitivity of the multilevel segmentation method proposed in this paper is significantly improved compared with the global random resonance results, indicating that the method proposed in this paper has obvious advantages in the segmentation of vessels with low-intensity levels. The image library was tested, and the experimental results showed that the new method has a better segmentation effect on low-contrast microscopic blood vessels. The new method not only makes full use of the noise for weak signal detection and segmentation but also provides a new idea of how to achieve multilevel segmentation and recognition of medical images.

A New Calibration Method and Device for Certified Flow Measurements With Laser Velocimetry

2012 ◽  
Author(s):  
Katsuaki Shirai ◽  
Lars Büttner ◽  
Jürgen Czarske ◽  
Carsten Kykal
Keyword(s):  
Positional Information ◽  
Calibration Method ◽  
Calibration Procedure ◽  
Uncertainty Budget ◽  
New Method ◽  
Direct Access ◽  
Flow Measurements ◽  
Laser Velocimetry ◽  
Traceability Chain ◽  
Calibration Methods

We aim to establish traceability at calibration and hence to enable a certified flow measurement with a calibrated measurement system. A new calibration method is presented for laser velocimetry. We develop a simple, unique method which establishes traceability of its uncertainty. The device is transportable and calibratable by any users for their own instruments on-site. Our new method requires only a rotating disk and a precision linear stage providing positional information. In former calibration methods, the uncertainty of the orbit radius of a scattering object was dominant due to the difficulty of accessing the true center of the rotation. The diffuculty was solved in our new method. The new method provides an accurate estimate of the orbit radius and hence the velocity of the calibration object through a linear regression. The calibration constant is obtained even without the need of direct access to the absolute value of the rotation radius. The uncertainty budget is examined throughout the calibration procedure. The traceability chain is established once the traceabilities are maintained to the translation stage and the motor used for rotating the calibration disk. The new method has been realized with three different calibration setups and their performances were investigated. We demonstrate that the new calibration method can achieve uncertainty down to 0.1%.

CT dose estimation using Gafchromic XR-CT film: Models comparison

2011 ◽  
Vol 46 (12) ◽  
pp. 2052-2055 ◽  
Author(s):  
Ying-Lan Liao ◽  
Hui-Chuan Kao ◽  
Keh-Shih Chuang ◽  
Chih-Ping Chen ◽  
Hui-Yu Tsai
Keyword(s):  
Dose Estimation ◽  
Ct Dose ◽  
Models Comparison

New Method for Reducing Coal Mine Gas Disasters via Directional Drilling and Hydraulic Jet

2021 ◽  
Author(s):  
Dingqi Li ◽  
Shuren Wang ◽  
Yubo Chen ◽  
Mingzhong Wang ◽  
Xu Chang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
New Method ◽  
Equivalent Diameter ◽  
Gas Extraction ◽  
Drilling Machine ◽  
Directional Drilling ◽  
Soft Coal ◽  
Porosity And Permeability ◽  
The Cost

Abstract Gas extraction is an important topic because of poor permeability and high gas seam in coal mines. A new method for reducing stress and improving permeability of coal seam was proposed to reduce the cost of gas extraction and danger of coal and gas outbursts. In this method, the roadway in coal floor was replaced with directional main borehole, directional branch boreholes were used to replace crossing holes, and soft coal was mined along soft sub layers using a directional drilling machine and a directional hydraulic jet. The numerical simulation showed that the porosity and permeability of coal seam significantly improve after soft sub layers being removed by the directional hydraulic jet. The application of the proposed method and its supporting equipment was carried out under the special gas conditions of Hudi Coal Mine. Results show that the soft coal is mined efficiently along the soft sub layer using the main borehole, branch boreholes, and directional hydraulic jet. Compared the hydraulic punching in the borehole with the ordinary drilling machine, the average speed of mining soft sub layers increased from 0.5 t/h to 3.6 t/h, the equivalent diameter of mining soft sub layers increased from 1.2 m to 7.6m, and the average flow of gas extraction increased from 0.41 m3/d to 6.25 m3/d. The conclusions obtained in this study can provide a reference to the similar coal mining methods.

New Continuous Dynamic Coupling for Three Component Modeling of Tool–Holder–Spindle Structure of Machine Tools With Modified Effected Tool Damping

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Mohammad Faraji Ghanati ◽  
Reza Madoliat
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Beam Theory ◽  
New Method ◽  
Equivalent Diameter ◽  
Dynamic Coupling ◽  
Tool Holder ◽  
Joint Parameters ◽  
Continuous Dynamic ◽  
Element Method

In machine dynamics, the tool point frequency response functions (FRFs) are employed to predict the stable machining conditions. In this paper, a combined analytical–experimental substructuring procedure is proposed to determine the tool point FRFs usable for different holder–tool configurations. Contact interface of holder–spindle and tool–holder is modeled using translational and rotational springs and dampers spread in the length of contact surface. These joint parameters are defined using finite element method. This enables the analyst to introduce the contact stiffness and damping in more detail with taking into consideration the variations of normal pressure in the tool–holder and holder–spindle joints. The dynamic analysis of the holder is done using Timoshenko beam theory by Tchebyshev method. The tool dynamics is modeled based on Euler–Bernoulli beam theory using the method of equivalent diameter. For the purpose of shifting the tool stability lobes to a higher level, tool damping parameter is modified by internal frictional damper and the effect is analyzed by analytical methods and experimental study. After joint parameters are defined continuously by finite element method, a new method for continuous dynamic coupling is presented. The method employs the measured spindle-machine FRFs and analytical models of the tool and holder to predict the tool tip FRFs. In this new method, continuous coupling in two separate domains of response model and modal model is presented. Such structural modeling avoids us to do complex modal tests for a different set of combinations of the holder and tool with specific milling machine. An experimental case study is provided to demonstrate the applicability of the proposed method in dynamic modeling of machine tool.

scholarly journals Model-based dose reconstruction for CT dose estimation

2017 ◽  
Vol 44 (9) ◽  
pp. e255-e263 ◽  
Author(s):  
Mingye Wu ◽  
Zhye Yin ◽  
Bruno De Man
Keyword(s):  
Dose Reconstruction ◽  
Dose Estimation ◽  
Model Based ◽  
Ct Dose

scholarly journals Methods of CT Dose Estimation in Whole-Body 18F-FDG PET/CT

2015 ◽  
Vol 56 (5) ◽  
pp. 695-700 ◽  
Author(s):  
Y. Inoue ◽  
K. Nagahara ◽  
Y. Tanaka ◽  
H. Miyatake ◽  
H. Hata ◽  
...  
Keyword(s):  
Fdg Pet ◽  
Whole Body ◽  
Dose Estimation ◽  
Ct Dose ◽  
Pet Ct ◽  
18F Fdg ◽  
Fdg Pet Ct

scholarly journals A New Method of Wavelength Calibration for LAMOST by Combining Short- and Long-Exposure Spectral Lines

2012 ◽  
Vol 29 (1) ◽  
pp. 66-71 ◽  
Author(s):  
G. H. Ye ◽  
J. Zhu ◽  
Z. F. Ye
Keyword(s):  
Spectral Lines ◽  
New Method ◽  
Short Exposure ◽  
Selected Lines ◽  
Wavelength Calibration ◽  
Calibration Methods

AbstractIn wavelength calibration using arc lines, the normal approach is to use the strongest unsaturated lines, leaving weak lines unused. A new method is proposed in this paper, which not only utilizes the strong spectral lines, but also makes most use of weak spectral lines. In order to validate the effectiveness of the method we propose, experiments are performed on simulated spectra. Firstly, two kinds of spectra are generated: one with a short exposure and another with a long exposure. Secondly, calibration lines are chosen from the short exposure and long exposure spectra separately according to some rules. Thirdly, the initial wavelength calibration is completed by using the selected short-exposure lines. Fourthly, the approximate centroids of the selected long-exposure lines are obtained by utilizing the result of the initial wavelength calibration. These are then adjusted iteratively to obtain the centroids. Finally, the selected lines from the short- and long-exposures are combined to obtain the final wavelength calibration. Compared with traditional calibration methods which only use short exposures and strong lines, the proposed method is shown to be more accurate.

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