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Result : Searchterm 'Magnetic Field' found in 5 terms [] and 219 definitions []
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Magnetic FieldForum -
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(H) The region surrounding a magnet (or current carrying conductor) is equipped with certain properties like that a small magnet in such a region experiences a torque that tends to align it in a given direction. Magnetic field is a vector quantity; the direction of the field is defined as the direction that the north pole of the small magnet points when in equilibrium.


MRI Safety Guidance
A magnetic field produces a magnetizing force on a body within it. Although the dangers of large magnetic fields are largely hypothetical, this is an area of potential concern for safety limits. Formally, the forces experienced by moving charged particles, current carrying wires, and small magnets in the vicinity of magnet are due to magnetic induction (B), which includes the effect of magnetization, while the magnetic field (H) is defined so as not to include magnetization. However, both B and H are often loosely used to denote magnetic fields.
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• Related Searches:
    • Larmor Frequency
    • Spin
    • Eddy Currents
    • Gradient Coil
    • Alignment
 
Further Reading:
  Basics:
Magnet basics
   by my.execpc.com    
Magnetic Field
   by hyperphysics.phy-astr.gsu.edu    
Magnetic Field
   by en.wikipedia.org    
How strong are magnets?
   by my.execpc.com    
  News & More:
Two stuck to MRI machine for 4 hrs
Tuesday, 11 November 2014   by www.mumbaimirror.com    
Commission proposes to revamp rules to protect EU workers from harmful electromagnetic fields
Tuesday, 14 June 2011   by finchannel.com    
Magnetic fields drive drug-loaded nanoparticles to reduce blood vessel blockages in an animal study
Monday, 19 April 2010   by www.eurekalert.org    
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Radiology  (9) Open this link in a new windowUltrasound  (2) Open this link in a new window
Magnetic Field Mapping
 
The mapping of the magnetic field by measuring or imaging the spatial distribution of magnetic field strength, can be performed by scanning with a probe and handles a large range of field strengths, but is slow and tedious. Accurate field maps can be made by measuring the Larmor frequency as a function of position.
The field must be homogeneous enough to allow MR imaging to be performed, than the magnetic field can be mapped by different methods.
1. The adaptation of chemical shift imaging.
2. The faster one measures the change in signal phase in an image obtained with a gradient echo pulse sequence resulting from a change in echo time TE, which is proportional to the local field strength.
Also useful is a spin echo pulse sequence with data collection from two time locations of the readout gradient and the data acquisition interval, where each having a known shift of the acquisition center away from the spin echo.
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MRI Safety Resources 
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Gradient Magnetic Field
 
A small linear magnetic field applied in addition to (superimposed on) the large static magnetic field in a MRI scanner. The strength (amplitude) and direction of the gradient fields change during the scan, which allows each small volume element (voxel) within the imaging volume to resonate at a different frequency. In this way, spatial encoding may be performed.
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Further Reading:
  Basics:
Magnetic Field
   by hyperphysics.phy-astr.gsu.edu    
Electrical eddy currents in the human body: MRI scans and medical implants
   by www.phy.olemiss.edu    
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News  (76)  Resources  (16)  Forum  (18)  
 
Magnetic Field Gradient
 
Magnetic field gradients are used to change the strength of the magnetic field Bo in a certain direction. Gradients are used in MR imaging with selective excitation to select a region for imaging and also to be able to encode the location of MR signals received from the object being imaged. The field strength is measured in Tesla per meter (T/m).
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• View the DATABASE results for 'Magnetic Field Gradient' (28).Open this link in a new window

 
Further Reading:
  Basics:
Magnetic Field
   by hyperphysics.phy-astr.gsu.edu    
Searchterm 'Magnetic Field' was also found in the following services: 
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Radiology  (9) Open this link in a new windowUltrasound  (2) Open this link in a new window
Gradient Magnetic Field Symbols
 
Gx, Gy, Gz - conventional symbols for gradient magnetic field. x, y, z denote spatial direction component of gradient, i.e. direction along that the field changes.
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