The Development Of A New Digital Magnetic Resonance Imaging Spectrometer Gradient Controller Based On PXIe Architecture

Magnetic resonance imaging(MRI)is a high-end imaging technology,since it introduced into clinical use in the 1980 s,due to its high resolution,non-ionizing radiation and other characteristics,it has increasingly shown its broad development prospects.Spectrometer is a high-end device that integrates advanced technologies in various disciplines such as machinery,electronics,and computers in the magnetic resonance imaging system.Its performance(noise,timing)will directly determine the quality of magnetic resonance imaging and Influence on medical diagnosis.The gradient controller is an important part of the spectrometer system.It mainly completes the calculation and generation of the gradient waveform.The resulting gradient waveform is amplified by the gradient amplifier to the coil to form a gradient field and completes the spatial positioning.In this paper,the basic of magnetic resonance physics,the working principle of spectrometer system and the important role of gradient controller are systematically studied.Based on the FPGA board card module PXIe-7972 and analog board NI-5741,combined with the basic principles of MRI and the generation mechanism of gradient magnetic field,a new generation of digital magnetic resonance spectrometer gradient controller was developed.The work includes the development of gradient controller,Eddy current compensation and gradient delay control.In terms of gradient controller,the basic functions and technical details of gradient controller are studied,and the basic functions of gradient controller are realized by using NI hardware.In terms of Eddy current,the reasons of Eddy current generation are analyzed in depth.The hardware scheme of measuring Eddy current based on PCB coil is proposed and the eddy current compensation function is realized.In the aspect of gradient delay,the causes of gradient delay and its influence on imaging are analyzed,and the solution is put forward,and the gradient delay control is realized.Finally,the gradient controller designed in this paper is connected to the alltech 1.5 T superconducting magnetic resonance systems.Through the GRE pulse sequence experiment,the water film image is finally obtained.