Page 255 - Biomedical Engineering and Design Handbook Volume 2, Applications
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234  DIAGNOSTIC EQUIPMENT DESIGN

                                                                      B
                                    B Gz                  y            G2

                                              y












                              z
                                                                           x



                                                B G1

                                                         φ











                                                                              z/a












                              FIGURE 8.3  A filamentary, single turn, saddle transverse gradient coil set is illustrated.
                              In addition, patterns for a typical unshieled transverse gradient coil is shown.

           8.3.3 Acoustic Noise
                       Time-varying magnetic field gradients spatially encode the anatomy of the patient in MR imaging.


                       Switched gradients may also produce acoustic noise. There are two sources of gradient-generated
                                                   l
                       acoustic noise. A conductor of length  carrying current I in a static magnetic field  B 0  will experi-

                       ence a force  F m  due to the magnet 48,49 :

                                                      F=Il ×  B 0                         (8.13)
                                                       m
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