CN203164402U

CN203164402U - Full digitalization multichannel single-board MRI spectrometer

Info

Publication number: CN203164402U
Application number: CN 201320097798
Authority: CN
Inventors: 潘文宇; 朱剑锋; 李璟
Original assignee: NINGBO XINGAOYI MAGNETISM CO Ltd
Current assignee: Xingaoyi Medical Equipment Co ltd
Priority date: 2013-03-04
Filing date: 2013-03-04
Publication date: 2013-08-28
Anticipated expiration: 2023-03-04

Abstract

The utility model relates to a full digitalization multichannel single-board MRI spectrometer. The MRI spectrometer is characterized by comprising a system master control module, a radiofrequency emitting module, a radiofrequency receiving module, and a gradient module. The system master control module is connected upwards with a host computer operated by a user, thereby realizing interaction of data and instructions. The radiofrequency emitting module, the radiofrequency receiving module, and the gradient module are connected upwards with the system master control module, and are connected downwards with a power amplification system. The power amplification system enhances transmitting/receiving signals. The system master control module is provided with a plurality of I/O interfaces used to monitor various parameters and output auxiliary control signals in an MRI system. The master control module, the radiofrequency emitting module, the radiofrequency receiving module, and the gradient module are integrated on a circuit board, and are connected with each other by circuit wiring. Compared with the prior art, the spectrometer is simple in structure, high in precision, small in size, and low in cost.

Description

Total digitalization hyperchannel veneer MRI spectrometer

Technical field

The utility model relates to a kind of totally digitilized hyperchannel veneer MRI spectrometer.

Background technology

Magnetic resonance imaging (Magnetic Resonance Imaging, MRI) be a kind of new and high technology in the medical image field, it utilizes the magnetic field of specific radio-frequency pulse and process space encoding, makes the proton resonance in the biosome produce signal, and machine is handled and imaging as calculated.Since coming out the seventies in 20th century, the MRI technical development is rapid, because but it has characteristics such as contrast height, the imaging of the many random layer bedding faults of imaging parameters, the pseudo-shadow interference of no bone, no ionising radiation, become one of state-of-the-art instrument in the imaging examination at present, be widely used in the clinical examination of partes corporis humani position.The MRI system can classify according to the intensity of main field: what magnetic field intensity was lower than 0.5T is low permanent-magnet type magnetic resonance, and magnetic field intensity is higher than the high-field magnetic resonance that is called of 1.0T, and main field is produced by superconducting coil.According to Larmor theorem:

B ₀Be main field strength,

Be gyromagnetic ratio, the proton gyromagnetic ratio of using for MRI is 42.58MHz/T, f ₀It is exactly resonant frequency.As seen, magnetic field intensity is more big, and resonant frequency is more high, and is just more high to the requirement of system signal processing power.

The MRI system comprises ingredients such as principal computer, spectrometer, power amplifier, main magnet, radio-frequency coil and gradient coil.Spectrometer is as the control platform of image scanning, it is the core component of whole M RI system, controlling generation, emission, reception and the processing of work schedule and the various signals of MRI system, the degree of perfection of its function has determined diversity and the convenience of image scanning, and the quality of its performance directly has influence on the quality of magnetic resonance image (MRI).

Traditional MRI spectrometer adopts analog circuitry processes in the control of emission, reception and the gradient signal of radiofrequency signal, circuit component is many, precision is lower, versatility is poor, along with the development of digital technology and the progress of IC chip manufacturing, the simulation spectrometer is just progressively eliminated by market.Existing Digital Spectrometer is mainly used in the low field MRI system, and faces the application demand of High-Field, all need introduce the analog frequency mixing unit usually on the basis of digital RF module, realizes the processing of total digitalization.In addition, conventional MRI spectrometer is formed by the polylith integrated circuit board, adopts bus mode to connect, and also needs the operation system usually, and resource consumption is big, complex structure, volume are big, expensive, in use in market certain limitation is arranged.

The utility model content

Technical problem to be solved in the utility model be at above-mentioned prior art provide that a kind of structure is simplified, precision height, volume is little, cost is low totally digitilized hyperchannel veneer MRI spectrometer.

The utility model solves the problems of the technologies described above the technical scheme that adopts: this total digitalization hyperchannel veneer MRI spectrometer, it is characterized in that: comprise main system control module, radiofrequency emitting module, Receiver Module and gradient modules, main system control module upwards links to each other with the principal computer of user's operation, realizes the mutual of data and instruction; Radiofrequency emitting module, Receiver Module and gradient modules upwards all link to each other with main system control module, and radiofrequency emitting module, Receiver Module and gradient modules all are connected with power amplifying system downwards, and power amplifying system is realized the enhancing of transmitting/receiving signal; Main system control module is provided with a plurality of I/O interfaces for the various parameters of monitoring MRI system and output auxiliary control signal; Main control module, radiofrequency emitting module, Receiver Module and gradient modules all are integrated on the circuit board, directly adopt wiring to link to each other each other.

Described main system control module comprises fpga chip, gigabit Ethernet control chip, PSRAM module, multi-channel A C and DAC converter, and wherein, gigabit Ethernet control chip, PSRAM module, multi-channel A C and DAC converter all link to each other with fpga chip.

Described radiofrequency emitting module comprises DUC module, DAC module and first interface circuit, and the input end of DUC module links to each other with fpga chip, and the output terminal of DUC module links to each other with the input end of DAC module, and the output terminal of DAC module links to each other with first interface circuit.

Described Receiver Module comprises ADC module, DDC module and second interface circuit, and the input end of ADC module links to each other with second interface circuit, and the output terminal of ADC module links to each other with the input end of DDC module, and the output terminal of DDC module links to each other with fpga chip.

Described gradient modules comprises DSP module, DAC module and the 3rd interface circuit, and the DSP module links to each other with fpga chip, and the input end of DAC module links to each other with the FPGA module, and the output terminal of DAC module links to each other with the 3rd interface circuit.

Compared with prior art, advantage of the present utility model is: all functional modules are integrated on the single circuit board, removed complicated total line traffic control, can compatiblely hang down field and high-field MRI systems simultaneously, and realized total digitalization in Signal Processing, broken away from the dependence to the analog frequency mixing unit, this spectrometer has characteristics such as structure is simplified, precision height, volume is little, cost is low, both can be used for the clinical medicine inspection, also can be advantageously used in the MRI investigation of R﹠D institution.

Description of drawings

Fig. 1 is that the functional module of totally digitilized hyperchannel veneer MRI spectrometer among the utility model embodiment connects block diagram;

Fig. 2 is that the circuit of totally digitilized hyperchannel veneer MRI spectrometer among the utility model embodiment connects block diagram.

Embodiment

Describe in further detail below in conjunction with the utility model of accompanying drawing embodiment.

Totally digitilized hyperchannel veneer MRI spectrometer as illustrated in fig. 1 and 2 comprises main system control module, radiofrequency emitting module, Receiver Module and gradient modules, and main system control module upwards links to each other with the principal computer of user's operation, realizes the mutual of data and instruction; Radiofrequency emitting module, Receiver Module and gradient modules upwards all link to each other with main system control module, and radiofrequency emitting module, Receiver Module and gradient modules all are connected with power amplifying system downwards, and power amplifying system is realized the enhancing of transmitting/receiving signal; Main system control module is provided with a plurality of I/O interfaces for the various parameters of monitoring MRI system and output auxiliary control signal; Main control module, radiofrequency emitting module, Receiver Module and gradient modules all are integrated on the circuit board, directly adopt wiring to link to each other each other.

Main system control module comprises fpga chip, gigabit Ethernet control chip, PSRAM module, multi-channel A C and DAC converter, and wherein, gigabit Ethernet control chip, PSRAM module, multi-channel A C and DAC converter all link to each other with fpga chip.Fpga chip is inner by programming, realize different logic functions, dock radiofrequency emitting module, Receiver Module and gradient modules respectively, simplify the structure on the one hand, reduce the wiring complexity, made being able to synchronously between each module realize in FPGA inside on the other hand.Consider that the function that fpga chip need realize is abundanter, and outward element is more, so fpga chip selects work clock to be not less than more than 400MHz, the logical block number 300K in the present embodiment, sheet internal storage capacity 8Mb is above, user's definable I/O number of pins is no less than 400 fpga chip.In main control module, FPGA makes an explanation to the scanning sequence of downloading from PC and parameter is distributed to other modules, after the scanning beginning, FPGA in accurate 3 tunnel trigger pips that produce of specific time point, controls radio-frequency transmissions by the sequence requirement respectively, radio frequency receives and the work of gradient modules coordinate synchronization.In scanning process, FPGA needs the magnetic resonance imaging K spatial data that Receiver Module obtains is carried out buffer memory and is uploaded to PC in real time.In addition, FPGA also realizes user-defined Working Status Monitoring, ecg-gating input, respiration gate control input, the output of radio frequency gate and other subsidiary functions by multi-functional I/O port.When carrying out Working Status Monitoring, FPGA is uploaded to PC with status information in real time, if fortuitous event with OnNow emergency protection handling procedure, ensures the safety of patient and magnetic resonance system.Ethernet control chip is responsible for realizing mutual between spectrometer and the PC, and in order to guarantee the transmission speed of multi-channel data, the chip that the utility model is selected for use is supported the gigabit Ethernet agreement.PSRAM is a kind of pseudo SRAM storer, and its storage inside particle is similar to SDRAM, and external interface is similar to SRAM.Compare with SDRAM, PSRAM does not need complicated control and flush mechanism, has promoted the convenience of using; Compare with SRAM, PSRAM has bigger capacity, and significantly the price of Jiang Diing has good cost performance.Based on above characteristics, PSRAM has obtained balance at capacity, speed, convenience and cost, therefore the utility model selects for use it as the main storage chip of spectrometer, more than the total volume 256Mb, it links to each other with FPGA, buffer memory imaging sequence parameter and the K spatial data after the Receiver Module acquisition process.Multi-functional I/O port is 16 passages altogether, comprise 4 road ADC, 4 road DAC and 8 way word I/O passages, wherein radio frequency output and the gate-control signal that receives be spectrometer to the essential control signal of radio-frequency (RF) power amplification, by digital I/O passage output, rest channels can be carried out self-defined according to user's needs.Common function comprises parameters such as monitoring of environmental temperature, radio frequency SAR value, power supply status, receives gates inputs such as electrocardio, breathing, output synchronously, clock signal of system etc.Performance requirement to A/D, D/A is not high herein, and cost and wiring are convenient considers that select ADC and the DAC chip of serial for use, precision is not less than 10bit, more than the sampling rate 100KSPS from saving.

Radiofrequency emitting module comprises DUC module, DAC module and first interface circuit, the input end of DUC module links to each other with fpga chip, the output terminal of DUC module links to each other with the input end of DAC module, the output terminal of DAC module links to each other with first interface circuit, in order to satisfy senior demands of applications, the radiofrequency emitting module of the utility model design has separate binary channels output, and radio-frequency transmissions adopts the method for quadrature amplitude modulation to produce the required radio-frequency pulse of magnetic resonance imaging.In radiofrequency emitting module, fpga chip is responsible for amplitude, frequency and the phase parameter of buffer memory baseband waveform and carrier wave, DUC module and DAC module are disposed accordingly, and when the trigger pip of radio-frequency transmissions arrived, control DUC module and the work of DAC module produced the radio-frequency pulse after the modulation.The built-in DDS of DUC module is modulated to the baseband waveform of low frequency on the high frequency carrier, and the parameter that can regulate comprises amplitude, frequency and phase place.The DAC module is responsible for the digital RF waveform transformation after the modulation is become simulating signal.First interface circuit carries out filtering with radiofrequency signal and amplifies laggard line output.DUC module and DAC module can be independently two chip blocks of difference, also can be integrated chips.In order to connect up convenient and to simplify structure, the utility model has been selected the integrated chip of inner integrated DUC and DAC for use, form binary channels for totally two, each passage can dispose separately and export, and for the application requirements of compatible High-Field and low magnetic resonance imaging, chip is selected and need be met the following conditions: the baseband waveform precision of DUC module is not less than 14bit, the frequency modulation (PFM) scope should be not less than 0～150MHz, minimum frequency modulation precision is less than 1Hz, minimum phase modulation precision is less than 0.1 °, the precision of DAC module is not less than 14bit, and the digital-to-analog conversion sampling rate is higher than 400MSPS.

Described Receiver Module comprises ADC module, DDC module and second interface circuit, and the input end of ADC module links to each other with second interface circuit, and the output terminal of ADC module links to each other with the input end of DDC module, and the output terminal of DDC module links to each other with fpga chip.The analog magnetic resonance signal that spectrometer receives is at first carried out filtering and amplification by interface circuit, carries out analog to digital conversion through ADC then and becomes digital signal.Magnetic resonance signal is a kind of modulation signal, and its useful signal is modulated on the high frequency carrier, need carry out real part I and the imaginary part Q of quadrature demodulation to obtain signal, and quadrature demodulation realizes by DDC.The NCO(digital controlled oscillator that DDC is built-in) produces that frequency is identical with carrier wave, the two-way reference signal of quadrature in phase, multiply each other required baseband signal real part IR and the imaginary part QR of acquisition imaging respectively with magnetic resonance signal.ADC and DDC can be two chips independently, also can be integrated a slice chips.For simplified structure and raising stability, what the utility model was selected for use is the integrated chip of inner integrated ADC and DDC, every chip has two input channels, share two and realize that four-way receives, and satisfies the requirement of main flow magnetic resonance multi-channel quadrature receiving coil (0 °, 90 °, 180 °, 270 °).In order to meet the needs of magnetic resonance imaging, chip performance should meet the following conditions: the ADC precision is not less than 14bit, and sampling rate is not less than 100MSPS, and the built-in NCO frequency coverage of DDC is not less than 0～150MHz, and minimum frequency modulation precision is less than 1Hz.After two-way baseband signal IR and QR entered FPGA, further high frequency noise was removed in filtering, carried out multistage extraction according to the requirement of imaging array resolution and reduced data transfer rate, obtained real part IK and the imaginary part QK of K spatial data.The K spatial data is buffered in by FPGA among the PSRAM of main system control module, is responsible for being uploaded to PC by main control module again.FPGA also is responsible for ADC and DDC are carried out parameter configuration and trigger control in addition.

Gradient modules comprises DSP module, DAC module and the 3rd interface circuit, and the DSP module links to each other with fpga chip, and the input end of DAC module links to each other with the FPGA module, and the output terminal of DAC module links to each other with the 3rd interface circuit.The DSP module receives the parameter relevant with gradient in the next imaging sequence of fpga chip transmission, carries out the calculating of gradient waveform accordingly, comprises the pre-emphasis calculating of basic waveform calculating, direction transformation, shimming biasing and compensation of eddy currents influence etc.The DSP module is selected and need be met the following conditions: floating type, support the above data length of 32bit, and dominant frequency is not less than 400MHz, and total storage space is not less than 4Mb in the sheet, supports DMA data transmission and external interrupt.Fpga chip is responsible for controlling the work of DSP module, and the gradient correlation parameter is passed to the DSP module, and obtains the result of gradient calculation.On the one hand, because gradient data comprises X, Y, Z three tunnel, and the gradient data of DSP module output is three the tunnel to export at interval, so fpga chip need be distributed data, the data of every road gradient is buffered in respectively among the FIFO.On the other hand, the data of DSP module output walk abreast, and the input of DAC is serial, so FPGA need carry out also-go here and there conversion (PSC earlier, Parallel-Series Convert), transfers data to DAC again, and be equipped with corresponding bit synchronization and frame synchronization clock.DSP and DAC control by the trigger pip of FPGA output, to finish synchronous coordination work according to the requirement of scanning sequence.DAC realizes the digital-to-analog conversion of gradient waveform, because the accuracy requirement to gradient signal is higher in the magnetic resonance imaging, so chip is selected and need be met the following conditions: the serial input, precision is not less than 20bit, and conversion ratio is not less than 100KHz, and signal to noise ratio (S/N ratio) is higher than 100dB.The 3rd interface circuit be responsible for to gradient signal amplify, filtering and single-ended transfer difference handle, Shu Chu X, Y, Z three tunnel gradients are differential analog signal at last.

The totally digitilized hyperchannel veneer spectrometer of the utility model design is core with the monolithic fpga chip, received and the gradient modules co-ordination by master control module controls radio-frequency transmissions, radio frequency, all functions are integrated on the single circuit board, the output of binary channels radio frequency, the four-way acquisition of magnetic resonance signals, compatible low and high field system can satisfy main flow magnetic resonance imaging demands of applications.

Claims

1. totally digitilized hyperchannel veneer MRI spectrometer, it is characterized in that: comprise main system control module, radiofrequency emitting module, Receiver Module and gradient modules, main system control module upwards links to each other with the principal computer of user's operation, realizes the mutual of data and instruction; Radiofrequency emitting module, Receiver Module and gradient modules upwards all link to each other with main system control module, and radiofrequency emitting module, Receiver Module and gradient modules all are connected with power amplifying system downwards, and power amplifying system is realized the enhancing of transmitting/receiving signal; Main system control module is provided with a plurality of I/O interfaces for the various parameters of monitoring MRI system and output auxiliary control signal; Main control module, radiofrequency emitting module, Receiver Module and gradient modules all are integrated on the circuit board, directly adopt wiring to link to each other each other.

2. totally digitilized hyperchannel veneer MRI spectrometer according to claim 1, it is characterized in that: described main system control module comprises fpga chip, ethernet control chip, PSRAM module, multi-channel A C and DAC converter, wherein, ethernet control chip, PSRAM module, multi-channel A C and DAC converter all link to each other with fpga chip.

3. totally digitilized hyperchannel veneer MRI spectrometer according to claim 2, it is characterized in that: described radiofrequency emitting module comprises DUC module, DAC module and first interface circuit, the input end of DUC module links to each other with fpga chip, the output terminal of DUC module links to each other with the input end of DAC module, and the output terminal of DAC module links to each other with first interface circuit.

4. totally digitilized hyperchannel veneer MRI spectrometer according to claim 2, it is characterized in that: described Receiver Module comprises ADC module, DDC module and second interface circuit, the input end of ADC module links to each other with second interface circuit, the output terminal of ADC module links to each other with the input end of DDC module, and the output terminal of DDC module links to each other with fpga chip.

5. totally digitilized hyperchannel veneer MRI spectrometer according to claim 2, it is characterized in that: described gradient modules comprises DSP module, DAC module and the 3rd interface circuit, the DSP module links to each other with fpga chip, the input end of DAC module links to each other with the FPGA module, and the output terminal of DAC module links to each other with the 3rd interface circuit.