Design On Some Modules Of Permanent Magnet MRI

The nuclear magnetic resonance can obtain the information of sample’s internal structure rapidly and accurately.Compared to other medical imaging equipment,The Magnetic Resonance Imaging can give transaxial, coronal and sagittal sections without damaging of organism.Because of low prices and easy maintenance,the open permanent magnet type of MRI is more and more important in medical examination.But as only a few large companies can provide MRI devices and the core technology grasps by the brandoutput country monopoly,the price of the MRIs is expensive.Thus,the self-study and design about the MRI has great significance.Based on the design of the open permanent magnet type of MRI,the paper completed the hardware and software design of some key modules,the main work are as follows:1、The design of the data transmission module. To satisfy the require of the receiver channel, this paper puts forward a designing program which uses STM32as a co-processor and LwIP as a protocol stack to achieve multichannel data transmission. Compared to the previous programs, this program greatly reduces the workload of the host processor FPGA, It is high real-time, modular and easy to expand. The paper will introduce the software and hardware platform of this program and the key of techniques. The result based on netio and on-line testing proves that this program meets the requirement of receiver channel and improves the manufacturing and maintainability of the system.2、The design of the transmitter module.The MRI of0.5T need to emission a carrier frequency of21.3MHz RF signal for the excitation of organism.The paper emphasizes on the hardware and software design of this module,from digital-analog conversion,filter model,quadrature modulation to power modulation.PCB and physical model are given.In software, arbitrary waveform generator based on FPGA and data transmission format are described.Finally,explains the test of this module in detail.3、The design of clock tree and power module.As a uniform hardware platform. we must consider the synchronization of the clock and the integrity of the power supply.The paper gives the hardware design of the clock module and highlight the key techniques of direct digital synthesis.The software design and test results are given.finally,the paper describes the hardware design of power module based on low dropout regulator, the hardware circuit and test results of this module are given.