CN203164401U - Gradient signal generator used for magnetic resonance imaging - Google Patents

Abstract

The utility model relates to a gradient signal generator used for magnetic resonance imaging. The gradient signal generator is characterized by comprising a DSP controller which is connected with a system bus, a FLASH storage which is connected with the DSP controller through a serial interface, three paths of digital analog converters whose input ends are connected with the DSP controller, and an interface circuit whose input ends are connected with output ends of the three paths of digital analog converters and output ends output three paths of X, Y, Z gradient signals required by magnetic resonance imaging scanning. Compared with the prior art, the gradient signal generator is advantaged in that a single DSP controller is a core of the gradient signal generator, the gradient signal generator comprises the FLASH, DAC, the analog interface circuit, etc., except the interfaces output finally must be analog circuits, other parts of the gradient generator enables full digitalization, and both of a digital portion and an analog portion use relatively less circuit components, and meanwhile circuit wiring is optimized, thereby realizing simplifying of structure and reduction of cost, and improving stability.

Description

A kind of generator of the gradient signal for magnetic resonance imaging

Technical field

The utility model relates to a kind of generator of the gradient signal for magnetic resonance imaging.

Background technology

Magnetic resonance imaging (Magnetic Resonance Imaging, MRI) be a kind of new and high technology in Medical Imaging, it utilizes the magnetic field of specific radio-frequency pulse and process space encoding, makes the proton resonance in biosome produce signal, and machine is processed and imaging as calculated.But because MRI has that contrast is high, the imaging of the many random layer bedding faults of imaging parameters, without the bone artifact disturb, without characteristics such as ionising radiations, become at present one of state-of-the-art instrument in imaging examination, be widely used in the clinical examination of partes corporis humani position.

Spectrometer is the Core Control Platform Based of magnetic resonance imaging system, comprises time schedule controller, radio-frequency signal generator, radio frequency receiver and gradient signal generator etc., is controlling generation, emission, reception and the processing of work schedule and the various signals of MRI system.Wherein, the gradient signal generator is the important component part of spectrometer, and it is responsible for producing the gradient magnetic signal, and the object in imaging space is carried out to 3-dimensional encoding (X/Y/Z direction), thereby provides positional information for image reconstruction.For magnetic resonance imaging, different imaging sequences need to produce different gradient waveforms, and the dirigibility of its function and the quality of performance, except affecting last picture quality, have also determined to apply the possibility of senior imaging sequence.

Traditional gradient signal generator is comprised of a large amount of electronic components, complex structure, and cost is higher.along with the development of integrated circuit technique, its structure has obtained simplification to a certain degree in recent years, but still can't break away from the dependence to the extensive programmable logic element such as FPGA, CPLD.

The utility model content

Technical problem to be solved in the utility model be for above-mentioned prior art provide that a kind of structure is simplified, perfect in shape and function, the generator of the gradient signal for magnetic resonance imaging that simultaneously there is superperformance.

The utility model solves the problems of the technologies described above adopted technical scheme: should, for the gradient signal generator of magnetic resonance imaging, it is characterized in that: comprise

Dsp controller, dsp controller has been used for storage, calculating and the output of digit gradient signal, the data bus of dsp controller is connected with the system bus of MRI spectrometer with address bus, and dsp controller also is connected with system bus in addition, be used for that the receiving system bus provides synchronous/trigger pip; Wherein, synchronizing signal is synchronous for the DSP clock system, and trigger pip is for the triggering that enables of gradient signal emission;

The FLASH storer, for storing the program firmware of dsp controller, be connected by serial line interface with dsp controller, when powering on, by serial line interface, program is loaded in DSP, and DSP is carried out to initialization;

The first digital to analog converter, convert the simulation gradient signal to for the digit gradient signal by the X road, and input end is connected with dsp controller, and output terminal is the single-ended gradient signal in X road of simulation;

The second digital to analog converter, convert the simulation gradient signal to for the digit gradient signal by the Y road, and input end is connected with dsp controller, and output terminal is the single-ended gradient signal in Y road of simulation;

The 3rd digital to analog converter, convert the simulation gradient signal to for the digit gradient signal by the Z road, and input end is connected with dsp controller, and output terminal is the single-ended gradient signal in Z road of simulation;

Interface circuit, this interface circuit is comprised of the operational amplifier filtering circuit, with the first digital to analog converter, the second digital to analog converter and the output terminal of the 3rd digital to analog converter, be connected, respectively X, Y, the Z road of the first digital to analog converter, the second digital to analog converter and the output of the 3rd digital to analog converter are simulated that single-ended gradient signal is amplified, filtering, and will simulate single-ended gradient signal and be converted to the analog differential gradient signal and exported.

The gradient signal generator that the utility model is designed, before starting, scanning receives corresponding gradient parameter and instruction, calculating and emission that can the complete independently gradient signal after scanning starts, without user or other modules, intervened, its accuracy on scanning sequence is provided by system bus, and synchronous/trigger pip is ensured.

Described dsp controller, FLASH storer, digital to analog converter and interface circuit all are integrated on the same circuit board.

The chip that described dsp controller adopts is required to be the floating type DSP met the following conditions: dominant frequency is not less than 333MHz, support the 32bit data length, the floating-point operation ability is not less than 1.8GFLOPS, and ROM and RAM capacity all are not less than 2Mb in sheet, built-inly is no less than 3 synchronous serial interfaces.

Described FLASH storer employing capacity is at least the serial FLASH memory of 2Mb.

Described the first digital to analog converter, the second digital to analog converter and the 3rd digital to analog converter are the DAC chip met the following conditions: have the serial data input interface, support the input of two's complement form, precision 16bit is above, sampling rate is not less than 96KHz, signal to noise ratio (S/N ratio) higher than 100dB.

Operational amplifier in described interface circuit adopts be not less than ± 10V of output voltage range, and input offset voltage is no more than 100 μ V, and common-mode rejection ratio is not less than 100dB, and switching rate is not less than the chip of 2V/ μ s.

Compared with prior art, the utility model has the advantage of: the utility model be take the monolithic dsp controller as core, comprise FLASH, DAC and analog interface circuit etc., except the interface of last output is necessary for mimic channel, the remainder of gradient generator has been realized total digitalization, and no matter is numerical portion or simulation part, all used less circuit component, wiring is optimized simultaneously, has realized the reduction with cost of simplifying of structure, and improved stability.

The accompanying drawing explanation

Fig. 1 is for the circuit block diagram of the gradient signal generator of magnetic resonance imaging in the utility model embodiment.

Embodiment

Below in conjunction with accompanying drawing, embodiment is described in further detail the utility model.

Gradient signal generator for magnetic resonance imaging, is characterized in that: comprise

Dsp controller, dsp controller has been used for storage, calculating and the output of digit gradient signal, the data bus of dsp controller is connected with the system bus of MRI spectrometer with address bus, and dsp controller also is connected with system bus in addition, be used for that the receiving system bus provides synchronous/trigger pip;

The FLASH storer, for storing the program firmware of dsp controller, be connected by serial line interface with dsp controller, when powering on, by serial line interface, program is loaded in DSP, and DSP is carried out to initialization;

The first digital to analog converter, convert the simulation gradient signal to for the digit gradient signal by the X road, and input end is connected with dsp controller, and output terminal is the single-ended gradient signal in X road of simulation;

The second digital to analog converter, convert the simulation gradient signal to for the digit gradient signal by the Y road, and input end is connected with dsp controller, and output terminal is the single-ended gradient signal in Y road of simulation;

The 3rd digital to analog converter, convert the simulation gradient signal to for the digit gradient signal by the Z road, and input end is connected with dsp controller, and output terminal is the single-ended gradient signal in Z road of simulation;

Interface circuit, this interface circuit is comprised of the operational amplifier filtering circuit, with the first digital to analog converter, the second digital to analog converter and the output terminal of the 3rd digital to analog converter, be connected, respectively X, Y, the Z road of the first digital to analog converter, the second digital to analog converter and the output of the 3rd digital to analog converter are simulated that single-ended gradient signal is amplified, filtering, and will simulate single-ended gradient signal and be converted to the analog differential gradient signal and exported.

The dsp controller that the utility model adopts is the floating type DSP met the following conditions: dominant frequency is not less than 333MHz, support the 32bit data length, the floating-point operation ability is not less than 1.8GFLOPS, and in sheet, ROM and RAM capacity all are not less than 2Mb, built-in 3 synchronous serial interfaces (SPORT) that are no less than.FLASH memory span used is 2Mb, adopts serial line interface, and also available more jumbo other serial FLASH chips replace.Three digital to analog converters used have the serial data input interface, support the input of two's complement form, and more than precision 16bit, sampling rate is not less than 96KHz, and signal to noise ratio (S/N ratio) is higher than 100dB.The main IC chip used in interface circuit is operational amplifier, its key technical index should meet following requirement: be not less than ± 10V of output voltage range, input offset voltage is no more than 100 μ V, and common-mode rejection ratio is not less than 100dB, and switching rate is not less than 2V/ μ s.In addition, by regulating supporting electric capacity, resistance value in interface circuit, can obtain different signal filtering effect and enlargement factor.

After the gradient signal generator powers on, at first dsp controller loads the program firmware of preserving in FLASH, carries out system initialization.After initialization completes, dsp controller is downloaded the gradient signal correlation parameter in the MRI scanning sequence by address and data bus from system bus, then start the calculating of digit gradient signal, content is followed successively by: basic waveform is calculated, according to the direction of any appointment, is carried out the angle rotation, for the pre-emphasis of eliminating vortes interference, process and superpose for the shimming first order biasing of compensating image space main field unevenness.The data that above calculating comprises X, Y, Z tri-tunnel gradients.After gradient calculation completes, because the digital to analog converter reception is serial input, in dsp controller, according to sampling rate and the data precision of digital to analog converter, configured 3 SPORT interfaces, the digital gradient data have been exported to digital to analog converter with serial mode.The bit synchronization signal of 3 interfaces and frame synchronizing signal are all used the homology clock in dsp controller herein, and carry out precise synchronization, guarantee three tunnel gradient outputs consistance in time.Three way weighted-voltage D/A converters convert digit gradient signal to single-ended simulation gradient signal.Interface circuit is first to the output of the three way weighted-voltage D/A converters amplification that gains, then signal is carried out to low-pass filtering, then single-ended signal is converted to differential signal, finally exports the required X of MRI scan, Y, Z tri-road gradient signals.

Claims (6)

1. the generator of the gradient signal for magnetic resonance imaging, is characterized in that: comprise

Dsp controller, dsp controller has been used for storage, calculating and the output of digit gradient signal, the data bus of dsp controller is connected with the system bus of MRI spectrometer with address bus, and dsp controller also is connected with system bus in addition, be used for that the receiving system bus provides synchronous/trigger pip;

The FLASH storer, for storing the program firmware of dsp controller, be connected by serial line interface with dsp controller, when powering on, by serial line interface, program is loaded in DSP, and DSP is carried out to initialization;

The first digital to analog converter, convert the simulation gradient signal to for the digit gradient signal by the X road, and input end is connected with dsp controller, and output terminal is the single-ended gradient signal in X road of simulation;

The second digital to analog converter, convert the simulation gradient signal to for the digit gradient signal by the Y road, and input end is connected with dsp controller, and output terminal is the single-ended gradient signal in Y road of simulation;

The 3rd digital to analog converter, convert the simulation gradient signal to for the digit gradient signal by the Z road, and input end is connected with dsp controller, and output terminal is the single-ended gradient signal in Z road of simulation;

Interface circuit, this interface circuit is comprised of the operational amplifier filtering circuit, with the first digital to analog converter, the second digital to analog converter and the output terminal of the 3rd digital to analog converter, be connected, respectively X, Y, the Z road of the first digital to analog converter, the second digital to analog converter and the output of the 3rd digital to analog converter are simulated that single-ended gradient signal is amplified, filtering, and will simulate single-ended gradient signal and be converted to the analog differential gradient signal and exported.

2. the generator of the gradient signal for magnetic resonance imaging according to claim 1, it is characterized in that: described dsp controller, FLASH storer, digital to analog converter and interface circuit all are integrated on the same circuit board.

3. the generator of the gradient signal for magnetic resonance imaging according to claim 1, it is characterized in that: the chip that described dsp controller adopts is required to be the floating type DSP met the following conditions: dominant frequency is not less than 333MHz, support the 32bit data length, the floating-point operation ability is not less than 1.8GFLOPS, ROM and RAM capacity all are not less than 2Mb in sheet, built-inly are no less than 3 synchronous serial interfaces.

4. the generator of the gradient signal for magnetic resonance imaging according to claim 1, it is characterized in that: described FLASH storer employing capacity is at least the serial FLASH memory of 2Mb.

5. the generator of the gradient signal for magnetic resonance imaging according to claim 1 is characterized in that: described the first digital to analog converter, the second digital to analog converter and the 3rd digital to analog converter be the DAC chip met the following conditions: there is the serial data input interface, support the input of two's complement form, precision 16bit is above, sampling rate is not less than 96KHz, signal to noise ratio (S/N ratio) higher than 100dB.

6. the generator of the gradient signal for magnetic resonance imaging according to claim 1, it is characterized in that: the operational amplifier in described interface circuit adopts be not less than ± 10V of output voltage range, input offset voltage is no more than 100 μ V, common-mode rejection ratio is not less than 100dB, and switching rate is not less than the chip of 2V/ μ s.

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