Shimming: Theory and Practice - UCLA-DOE
Shimming: Theory and Practice - UCLA-DOE
Shimming: Theory and Practice - UCLA-DOE
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Heres a simple example: 1 shim (z), 3 spatial positions<br />
a 1 a 1 z 1<br />
a 2 z 1 = a 2 z 1<br />
a 3 a 3 z 1<br />
A<br />
s<br />
a 1 z 1 – b 1<br />
a 2 z 1 – b 2<br />
a 3 z 1 – b 3<br />
To get the optimal shim settings, the square<br />
of this vector must be minimized.<br />
A . s - b<br />
Bruker uses 128x32x32 points (that is: 32 increments in each of the G x<br />
<strong>and</strong> G y dimensions, <strong>and</strong> 128 points in the acquisition) with a field of view<br />
of 28x6.4x6.4 mm.<br />
So there are 131,072 voxels, roughly 35,000 of which are contained in<br />
the sample.<br />
Each of these volume elements is 8.8 x 10 -9 liters.
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