scholarly journals The management of error in ultrasound fetal growth monitoring

Ultrasound ◽  
2020 ◽  
pp. 1742271X2094574
Author(s):  
Nicholas J Dudley
Keyword(s):  
Image Quality ◽  
Measurement Method ◽  
Image Plane ◽  
Acceptance Testing ◽  
Growth Monitoring ◽  
Error Sources ◽  
Fetal Size ◽  
Potential Impact ◽  
Clinically Significant ◽  
Improving Accuracy

It is important to understand the uncertainty in fetal measurements when using them in the management of pregnancy. The aim of this essay is to provide background on errors and uncertainty, describing error sources and their potential impact, with guidance on improving accuracy. Errors can be systematic or random, arising from equipment, image plane selection, measurement method and caliper placement and influenced by image quality, training and experience. The uncertainty in measurements is larger than clinically significant differences in fetal size and growth. Errors can be reduced by implementing equipment acceptance testing, written procedures, training and audit.

scholarly journals CALCULATION OF A GLARE STOP FOR TWO-MIRROR EXTRA-FOCAL OBJECTIVE

2017 ◽  
Vol 8 (4) ◽  
pp. 327-333
Author(s):  
L. F. Zambrano ◽  
N. K. Artyukhina ◽  
L. V. Peroza
Keyword(s):  
Image Quality ◽  
Image Plane ◽  
Stray Light ◽  
Geometric Constructions ◽  
Calculation Algorithm ◽  
Second Stage ◽  
Mathematical Expressions ◽  
Intermediate Image ◽  
Two Stages ◽  
Light Beams

Recently, efforts to improve optical characteristics in canonical mirror systems, including aspherical surfaces and corrective aberration capabilities. At the same time, much attention is paid to the development of new optical schemes of two-mirror objectives. Development measures to protect the image plane from stray light and harmful flows with minimal vignetting and screening is one of the most perspective ways for improving the image quality objectives. The only method to eliminate or even reduce these non-constructive rays is to set glare stops. The aim of the work was an improving method for constructing a glare stop to protect the image plane and the creation of a calculation algorithm of glare stop for protecting the image plane based on two-mirror extra-focal objectives.The study was conducted in two stages. In the course of the first stage, the positions of screening and intermediate image plane were obtained, as well as the central screening coefficient. At the second stage, an arrangement for the position of glare stop is proposed using the algorithm calculation. Thus, mathematical expressions were achieved by geometric constructions. The relation of the screening coefficient with the distance between the surfaces of the mirrors and the height of the paraxial rays is established. А representation of vignetting diagram for two-mirror extra-focal objective with D/f´ = 1 : 1,3 and 2ω = 4° was realized. TheQestimation of vignetting of inclined light beams is k= 0,56.

A novel composite-structure-light 3D measurement method for improving accuracy based on two plus one phase shifting algorithm

Optik ◽  
2013 ◽  
Vol 124 (5) ◽  
pp. 461-465 ◽  
Author(s):  
Ai-ping Zhai ◽  
Yi-ping Cao ◽  
Zhen-fen Huang ◽  
Yu-hang He ◽  
Ming-teng Lu
Keyword(s):  
Composite Structure ◽  
Measurement Method ◽  
Phase Shifting ◽  
3D Measurement ◽  
Improving Accuracy ◽  
Structure Light

Study on Accuracy Measure of Trigonometric Leveling

2013 ◽  
Vol 329 ◽  
pp. 373-377 ◽  
Author(s):  
Xian Ping Zhou ◽  
Ming Sun
Keyword(s):  
Reference Value ◽  
Angle Measurement ◽  
Determination Method ◽  
Vertical Angle ◽  
Error Sources ◽  
Total Station ◽  
Long Period ◽  
Height Determination ◽  
Accuracy Measure ◽  
Improving Accuracy

How to reduce the errors of the total station in vertical angle measurement is a main problem for improving the accuracy of trigonometric leveling. The leveling method combining the total station with a tracking bar is becoming increasingly more popular, and also the limitations of the traditional trigonometric leveling method have been shown. After a long period of exploration, a new method is proposed for trigonometric leveling. The results show that the error sources of trigonometric leveling are reduced by the method combining with the total station on any spot, and also instrument height and prism height are unnecessarily measured in each determination, so that the field workload and the error sources for improving accuracy are reduced, and then the accuracy of trigonometric leveling is further improved and the speed of implementing the leveling becomes faster. This height determination method is with certain applicability and reference value in the practical work.

Mathematical Model and Error Analysis of Coordinate Measuring Arm with Revo Revolving Body

2011 ◽  
Vol 52-54 ◽  
pp. 156-161 ◽  
Author(s):  
Lei Zhao ◽  
Shu Gui Liu
Keyword(s):  
Mathematical Model ◽  
Measurement Accuracy ◽  
System Model ◽  
Error Sources ◽  
Spherical Domain ◽  
New Type ◽  
Space Coordinate ◽  
Improving Accuracy ◽  
Revolving Body ◽  
The Mathematical Model

A new type of coordinate measuring arm with a Revo revolving body which can realize quick measuring in spherical domain has high stability, fast measuring speed and high accuracy compared with common coordinate measuring arm. We use the method of space coordinate transformation to solve the problem that the transformation matrix can’t be got from Revo body to test head by DH method, and apply DH theory to build the mathematical model of system. The system model is verified right by sketching. The error model is built and the effect of measurement accuracy from all error sources is deeply analyzed. It presents a theory foundation for further researching on improving accuracy of this new type of coordinate measuring arm.

scholarly journals A novel method to assess the spatiotemporal image quality in fluoroscopy

2021 ◽  
Author(s):  
Pascal Monnin ◽  
Anaïs Viry ◽  
Jérôme Damet ◽  
Marie Nowak ◽  
Veronika Vitzthum ◽  
...  
Keyword(s):  
Image Processing ◽  
Image Quality ◽  
Temporal Resolution ◽  
Temporal Frequency ◽  
Image Plane ◽  
Dynamic Imaging ◽  
Rectilinear Motion ◽  
Multiple Parameters ◽  
Frame System

Abstract Objectives. The planar formulation of the noise equivalent quanta (NEQ) and detective quantum efficiency (DQE) used to assess the image quality of projection images does not deal with the influence of temporal resolution on signal blurring and image noise. These metrics require correction factors based on temporal resolution when used for dynamic imaging systems such as fluoroscopy. Additionally, the standard NEQ and detector DQE are determined on pre-processed images in scatter-free conditions for effective energies produced by additional aluminium or copper filters that are not representative of clinical fluoroscopic procedures. In this work, we developed a method to measure “frame NEQ” and “frame system DQE” which include the temporal frequency bandwidth and consider the anti-scatter grid, the detector and the image processing procedures for beam qualities with scatter fractions representative of clinical use. Approach. We used a solid water phantom to simulate a patient and a thin copper disc to measure the spatial resolution. The copper disc, set in uniform rectilinear motion in the image plane, assessed the temporal resolution. These new metrics were tested on two fluoroscopy systems, a C-arm and a floor-mounted cardiology, for multiple parameters: phantom thicknesses from 5 to 20 cm, frame rates from 3 to 30 fps, spatial and temporal image processing of different weights. Main results. The frame NEQ correctly described the image quality for different scatter conditions, temporal resolutions and image processing techniques. The frame system DQE varied between 0.38 and 0.65 within the different beam and scatter conditions, and correctly mitigated the influence of spatial and temporal image processing. Significance. This study introduces and validates an unbiased formulation of in-plane NEQ and system DQE to assess the spatiotemporal image quality of fluoroscopy systems.

Improving accuracy for measuring the ship's magnetic moment in the far field

2021 ◽  
pp. 67-72
Author(s):  
Aleksei A. Zateev ◽  
Yury M. Ivanov ◽  
Valentin G. Semenov
Keyword(s):  
Magnetic Moment ◽  
Measurement Method ◽  
Hysteresis Loops ◽  
New Method ◽  
Far Field ◽  
Standard Samples ◽  
Order Of Magnitude ◽  
Differential Magnetometer ◽  
Improving Accuracy ◽  
The Magnetic Field

The magnetic moment of the ship is measured to control its protection from magnetic mines and to control the stealth by the magnetic field. A modification of the measurement method using a three-component differential magnetometer is considered. Using computer simulation, the errors of the new method are compared with those of the known analogues and its advantage in accuracy is established (almost by an order of magnitude). It is shown that the new method can also be used for magnetic models of ships and standard samples of magnetic materials to determine their components of the hysteresis loops by magnetization.

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