具有独立延时功能的脉冲序列发生器

摘要

在磁共振成像(Magnetic Resonance Imaging,MRI)系统中,谱仪是中心控制单元,其脉冲序列发生器输出的多通道指令分别控制各硬件部件协调工作,从而采集数据并重建图像,各硬件部件之间的相对延时会影响磁共振图像的质量或导致系统无法采集到图像.为了解决这一问题,本文设计了每个输出通道均具有可调延时功能的脉冲序列发生器,每一路通道的最大延时值为819μs,延时步进值为50 ns,可实现对相对延时的精确补偿.由于延时功能是通过在脉冲序列发生器每个输出通道上添加独立延时电路实现的,因此具有结构简单,灵活性高的优点.%Spectrometer is a key control unit in magnetic resonance imaging (MRI) systems. Pulse programmer of the spectrometer outputs multi-channel instructions to control each hardware component separately, and to coordinate work, collect data, and reconstruct image. Relative time delay among the hardware components may disable the system, or affect the quality of the images acquired. This work designed a pulse programmer whose output channels all boasted adjustable time delay capability. The maximal time delay for each channel was 819 μs, and the step time delay was 50 ns. As such, accurate compensation to relative time delay could be achieved. By adding independent delay circuits on every output channel of the pulse programmer, adjustable time delay capability was achieved. The pulse programmer proposed has the advantages of simple structure and high flexibility.