Friday, November 17, 2006
EM simulation cuts cost of MRI enclosures
Electromagnetic simulation substantially reduced the cost of the protective shields surrounding magnetic resonance imaging (MRI) suites at one Chicago hospital.
Electromagnetic simulation substantially reduced the cost of the protective shields surrounding magnetic resonance imaging (MRI) suites at one Chicago hospital. Use of 3D electromagnetic simulation software, from Vector Fields, enabled engineers at Lindgren RF Enclosures to quickly evaluate different shield materials and thicknesses to achieve the desired level of protection at the lowest price. Also by using simulation as part of the design process they were able to ensure that the shields would provide adequate protection prior to installation, eliminating the need for costly post installation modifications.
Information collated also helped system selection at the initial purchasing stage.
An MRI system generates an image of the body through the use of a very strong magnetic field, which causes every molecule in the body to align within the magnetic field.
The RF signals cause the molecules to vibrate which pickup coils detect.
Since different tissues vibrate in response to different frequencies, an image of the tissues can be generated by the system pulsing at different radio frequencies.
An MRI scan resembles an X-ray but is better for viewing soft tissues such as liver and heart.
The magnetic field of the MRI system is so strong that it would extend great distance and without shielding, present a potential health hazard, particularly to people with pacemakers and metal implants.
Similarly electronic and other imaging systems may be disrupted by the magnetic filed.
Shielding is also necessary to protect the MRI system from the effect of large metal objects such as metallic trolleys or even vehicles passing outside, all of which may affect imaging.
As surroundings and fixtures are particular to an installation each MRI shield is unique.
Time consuming calculations are normally needed to see how well the enclosure would contain the field but even then, exact results would not be known until the shield had been built and readings taken.
The simulation makes the calculations both easier and more accurate and makes it economically viable to check a variety of designs, shapes and materials.
Reduced design times means lower costs, optimised designs lower build costs and post installation modifications are also minimised.
Lindgren engineers chose Opera software from Vector Fields because its graphical user interface makes it easy to 'ring the changes' modelling many MRI systems and configurations.
In addition its powerful scripting language makes it possible to automate the analysis, facilitating evaluation of all the designs.
The package also offers outstanding technical depth and a very robust solver that converges to a solution in even the most complex geometries.
A 2D model of the proposed shield was generated from MRI system data and the architect's plans of the locations and then extended into 3D.
The 3D model was detailed and realistic, and included openings for such as windows and doors.
The program can then divide the model into finite elements.
A comprehensive library of materials data, including B-H properties is held within the Vector Fields system, which equates input data on the particular material parameters, chemical composition, material state from heat-treatment etc as entered by the engineers.
Tosca, a electromagnetic analysis solver, also from Vector Fields, then predicted how well the shield would perform.
Tosca shows where any shield material is saturated by graphs, histograms and contour plots of the magnetic field superimposed on the model, clearly indicating where the material is inadequate and where surplus.
Corrections then re-evaluated provided the final cost effective solution.
Not only did the software package enable Lindgren to optimise several systems for the same hospital, but also assisted in the initial purchase evaluation by being able to quantify costs, build schedules and many other aspects of different types of machine.
The software simulation package from Vector Fields is designed for analyses of any EMI screen currently essential under EEC regulations for all equipment generating radio frequency and electromagnetic fields.
Vector Fields offers a consultancy service particularly for customers with only an occasional requirement for this type of analysis.
Electromagnetic simulation substantially reduced the cost of the protective shields surrounding magnetic resonance imaging (MRI) suites at one Chicago hospital. Use of 3D electromagnetic simulation software, from Vector Fields, enabled engineers at Lindgren RF Enclosures to quickly evaluate different shield materials and thicknesses to achieve the desired level of protection at the lowest price. Also by using simulation as part of the design process they were able to ensure that the shields would provide adequate protection prior to installation, eliminating the need for costly post installation modifications.
Information collated also helped system selection at the initial purchasing stage.
An MRI system generates an image of the body through the use of a very strong magnetic field, which causes every molecule in the body to align within the magnetic field.
The RF signals cause the molecules to vibrate which pickup coils detect.
Since different tissues vibrate in response to different frequencies, an image of the tissues can be generated by the system pulsing at different radio frequencies.
An MRI scan resembles an X-ray but is better for viewing soft tissues such as liver and heart.
The magnetic field of the MRI system is so strong that it would extend great distance and without shielding, present a potential health hazard, particularly to people with pacemakers and metal implants.
Similarly electronic and other imaging systems may be disrupted by the magnetic filed.
Shielding is also necessary to protect the MRI system from the effect of large metal objects such as metallic trolleys or even vehicles passing outside, all of which may affect imaging.
As surroundings and fixtures are particular to an installation each MRI shield is unique.
Time consuming calculations are normally needed to see how well the enclosure would contain the field but even then, exact results would not be known until the shield had been built and readings taken.
The simulation makes the calculations both easier and more accurate and makes it economically viable to check a variety of designs, shapes and materials.
Reduced design times means lower costs, optimised designs lower build costs and post installation modifications are also minimised.
Lindgren engineers chose Opera software from Vector Fields because its graphical user interface makes it easy to 'ring the changes' modelling many MRI systems and configurations.
In addition its powerful scripting language makes it possible to automate the analysis, facilitating evaluation of all the designs.
The package also offers outstanding technical depth and a very robust solver that converges to a solution in even the most complex geometries.
A 2D model of the proposed shield was generated from MRI system data and the architect's plans of the locations and then extended into 3D.
The 3D model was detailed and realistic, and included openings for such as windows and doors.
The program can then divide the model into finite elements.
A comprehensive library of materials data, including B-H properties is held within the Vector Fields system, which equates input data on the particular material parameters, chemical composition, material state from heat-treatment etc as entered by the engineers.
Tosca, a electromagnetic analysis solver, also from Vector Fields, then predicted how well the shield would perform.
Tosca shows where any shield material is saturated by graphs, histograms and contour plots of the magnetic field superimposed on the model, clearly indicating where the material is inadequate and where surplus.
Corrections then re-evaluated provided the final cost effective solution.
Not only did the software package enable Lindgren to optimise several systems for the same hospital, but also assisted in the initial purchase evaluation by being able to quantify costs, build schedules and many other aspects of different types of machine.
The software simulation package from Vector Fields is designed for analyses of any EMI screen currently essential under EEC regulations for all equipment generating radio frequency and electromagnetic fields.
Vector Fields offers a consultancy service particularly for customers with only an occasional requirement for this type of analysis.
# posted by Swathi @ 10:41 PM 
