A PHP Error was encountered

Severity: Warning

Message: file_get_contents(https://...@pubfacts.com&api_key=b8daa3ad693db53b1410957c26c9a51b4908&a=1): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests

Filename: helpers/my_audit_helper.php

Line Number: 176

Backtrace:

File: /var/www/html/application/helpers/my_audit_helper.php
Line: 176
Function: file_get_contents

File: /var/www/html/application/helpers/my_audit_helper.php
Line: 250
Function: simplexml_load_file_from_url

File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3122
Function: getPubMedXML

File: /var/www/html/application/controllers/Detail.php
Line: 575
Function: pubMedSearch_Global

File: /var/www/html/application/controllers/Detail.php
Line: 489
Function: pubMedGetRelatedKeyword

File: /var/www/html/index.php
Line: 316
Function: require_once

A Method for Reducing Secondary Field Effects in Asymmetric MRI Gradient Coil Design. | LitMetric

Goal: This research introduces an original method for the design of MRI gradient coils that reduces secondary field effects created by eddy current coupling. The method is able to deal with asymmetric coils and provides a new way to ensure a reduction in the magnitude of the eddy current induced fields.

Methods: New constraints are introduced at the surface of passive objects to bind the normal field component below a given value. This value is determined by first treating the passive surface as an active surface, and then, calculating the ideal stream function on that surface to produce the desired secondary field. Two coils were designed, one to image the knee and the other to image the head and neck.

Results: The secondary field was analyzed using linear regression and was found to improve the secondary field from 10.41 to 0.498 mT/m and from 7.84 to 0.286 mT/m in the examples used. The power loss in the passive structure also decreased to below 1% of the original value using the new method.

Conclusion: The method shows the ability to constrain the field to values below the minimum seen under the traditional approaches.

Significance: This will allow the design of asymmetric systems with highly linear, reduced magnitude of secondary fields and may lead to better image quality.

Download full-text PDF

Source
http://dx.doi.org/10.1109/TBME.2015.2479230DOI Listing

Publication Analysis

Top Keywords

secondary field
20
field effects
8
mri gradient
8
eddy current
8
field
7
secondary
6
method
4
method reducing
4
reducing secondary
4
effects asymmetric
4

Similar Publications

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!