| 摘要 |
A magnetic resonance imaging magnet, gradient coil, and RF coil assembly is controlled by a workstation (40). The workstation (40) includes an operator input (46, 48) and a display system (58) including a video monitor (44) for displaying human-readable images reconstructed from magnetic resonance data. A scan/reconstruction rack (50) includes a scan processor (60) which controls scan parameters and a reconstruction processor (64) and associated hardware for reconstructing received magnetic resonance signals into the image representation. A scan sequencer (52) includes a master microcode board (90) which controls the scan sequencer in accordance with instructions received from the scan processor (60). The scan processor loads a series of codes describing gradient and RF waveform profiles into memories (130) of each of a plurality of profile channels (100, 102, 104, 106, 110, 112, 114). Associated state machines (126) of each channel under control of a clock (138) step the pulse information from the memory (130) to respective output registers. The outputs from four of the channels for controlling the magnetic field gradients are connected to an obliquer (94) which processes the four outputs with a matrix to generate x, y, and z gradient components. The gradient components are connected through digitally controlled pre-emphasis circuits (150) to the gradient coils. The rest of the channels are connected to a frequency synthesizer (116) which provides frequency information for driving the radio frequency coil.
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