Calibration Method, Device, Computer Equipment and Storage Medium of Radio Frequency System

Abstract

The present application relates to a calibration method, device, computer device and storage medium for a radio frequency system. The method determines the relative delay between a radio frequency transmitting system and a radio frequency receiving system by obtaining the actual center time of the echo signal on each receiving channel and the theoretical center time of the echo signal, and then calibrating the relative delay. The above method can measure the relative delay of the radio frequency system only based on the actual center time and the theoretical center time of the echo signal. Compared with the traditional method for measuring the relative delay, it does not require complex means such as image or phase analysis. The above method is simpler and does not require the introduction of new hardware, greatly reducing the calibration cost.

Description

Technical Field

[0001] The present application relates to the field of nuclear magnetic resonance technology, and particularly to a calibration method, device, computer device, and storage medium for a radio frequency system. Background Art

[0002] With the development of nuclear magnetic resonance technology, magnetic resonance imaging systems have been widely used in the medical field. The radio frequency system is one of the core systems in the magnetic resonance imaging process. The radio frequency system includes a radio frequency transmitting system and a radio frequency receiving system. The radio frequency transmitting system is mainly responsible for generating and amplifying the radio frequency waveform signals defined in the pulse sequence program to complete the excitation of tissues, and the radio frequency receiving system receives the magnetic resonance signals from the magnetic resonance coil, amplifies and samples them to complete the digital acquisition of the magnetic resonance signals.

[0003] Currently, both the radio frequency transmitting system and the radio frequency receiving system have multiple levels of subsystems, and there are significant differences in their structures, operating powers, numbers of channels, etc. Therefore, the time intervals from receiving instructions to the instructions taking effect are not exactly the same, that is, a relative delay of instructions between the radio frequency transmitting system and the radio frequency receiving system is generated. Since all magnetic resonance imaging starts from the radio frequency pulse emission, after a series of encodings, the final purpose is to receive signals. Therefore, the relative delay of the radio frequency system will greatly affect the imaging quality and effect, and even prevent imaging. Therefore, many existing technologies have proposed methods for calibrating the relative delay of the radio frequency system to improve the magnetic resonance imaging quality.

[0004] However, most of the existing calibration methods are complex, and some calibration methods even require the introduction of new hardware, resulting in high calibration costs. Summary of the Invention

[0005] Based on this, in view of the above technical problems, it is necessary to provide a calibration method, device, computer device, and computer-readable storage medium for a radio frequency system that is simple and can effectively reduce the hardware calibration cost of the radio frequency system.

[0006] In a first aspect, the present application provides a calibration method for a radio frequency system. The method includes:

[0007] Obtaining the actual center time of the echo signal on each receiving channel;

[0008] Obtaining the theoretical center time of the echo signal on each receiving channel;

[0009] Determining the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual center time and the theoretical center time of the echo signal on each receiving channel;

[0010] Calibrating the relative delay.

[0011] In one embodiment, the correction for the relative delay includes:

[0012] If the relative delay is greater than a preset delay threshold, adjust the radio frequency (RF) transmission instruction of the RF transmission system or adjust the RF reception instruction of the RF reception system to correct the relative delay;

[0013] If the relative delay is not greater than the preset delay threshold, correct the relative delay by means of time-domain signal translation or frequency-domain phase compensation.

[0014] In one embodiment, the determination of the relative delay between the RF transmission system and the RF reception system according to the actual center time of the echo signal and the theoretical center time of the echo signal on each reception channel includes:

[0015] Determine the difference between the theoretical center time and the actual center time of the echo signal on each reception channel;

[0016] According to the difference between the theoretical center time and the actual center time of the echo signal on each reception channel, calculate the relative delay of each reception channel relative to the target transmission channel; the target transmission channel is the transmission channel used during the current acquisition among all the transmission channels included in the RF transmission system.

[0017] In one embodiment, the adjustment of the RF transmission instruction of the RF transmission system or the adjustment of the RF reception instruction of the RF reception system to correct the relative delay includes:

[0018] According to the relative delay of each reception channel in the RF transmission system relative to the target transmission channel, respectively adjust the sending time of the RF reception instruction of each reception channel or the sending time of the RF transmission instruction of the target transmission channel to correct the relative delay of each reception channel relative to the target transmission channel.

[0019] In one embodiment, the adjustment of the RF transmission instruction of the RF transmission system or the adjustment of the RF reception instruction of the RF reception system to correct the relative delay includes:

[0020] Calculate the average delay of the relative delays of all reception channels relative to the target transmission channel;

[0021] According to the average delay, uniformly adjust the sending time of the RF reception instruction of each reception channel or the sending time of the RF transmission instruction of the target transmission channel to correct the relative delay of each reception channel relative to the target transmission channel.

[0022] In one embodiment, if the RF receiving system receives multiple echo signals, determining the relative delay between the RF transmitting system and the RF receiving system according to the actual center time of the echo signal on each receiving channel and the theoretical center time of the echo signal includes:

[0023] Determining the difference between the actual center time of each of the multiple echo signals on each receiving channel and the theoretical center time of the corresponding multiple echo signals;

[0024] Obtaining the average difference of the differences on each receiving channel or the average difference weighted by the echo signal intensity of the differences;

[0025] Calculating the relative delay of each receiving channel relative to the target transmitting channel according to the average difference of the differences on each receiving channel or the average difference weighted by the echo signal intensity of the differences.

[0026] In one embodiment, adjusting the RF transmission instruction of the RF transmitting system or adjusting the RF reception instruction of the RF receiving system to correct the relative delay includes:

[0027] If the relative delay indicates that the instruction time of the RF receiving system is greater than the instruction time of the RF transmitting system, advancing the sending time of the RF reception instruction of the RF receiving system relative to the sending time of the RF transmission instruction of the RF transmitting system by the time corresponding to the relative delay, or delaying the sending time of the RF transmission instruction of the RF transmitting system relative to the sending time of the RF reception instruction of the RF receiving system by the time corresponding to the relative delay;

[0028] If the relative delay indicates that the instruction time of the RF receiving system is less than the instruction time of the RF transmitting system, delaying the sending time of the RF reception instruction of the RF receiving system relative to the sending time of the RF transmission instruction of the RF transmitting system by the time corresponding to the relative delay, or advancing the sending time of the RF transmission instruction of the RF transmitting system relative to the sending time of the RF reception instruction of the RF receiving system by the time corresponding to the relative delay.

[0029] In one embodiment, correcting the relative delay by means of time-domain signal translation or frequency-domain phase compensation includes:

[0030] Performing time-domain translation on the echo signal on the receiving channel and performing Fourier transform on the translated signal to complete the correction of the relative delay on the receiving channel;

[0031] Alternatively, perform a Fourier transform on the echo signal on the receiving channel, and perform phase compensation on the transformed signal to complete the correction of the relative delay on the receiving channel.

[0032] In one embodiment, the correction of the relative delay by means of time-domain signal translation includes:

[0033] Perform time-domain translation on the radio frequency signal on the transmitting channel, and perform a Fourier transform on the translated signal to complete the correction of the relative delay on the receiving channel.

[0034] In one embodiment, in the gradient system corresponding to the radio frequency transmitting system and the radio frequency receiving system, set the gradient to exist from the start to the end of the radio frequency pulse sequence emitted by the radio frequency transmitting system, and the gradient ramp time is greater than a preset time threshold from the start time of the first radio frequency pulse sequence.

[0035] In one embodiment, the obtaining of the actual center time of the echo signal on each receiving channel includes:

[0036] Obtain the sampling point corresponding to the maximum intensity value of the echo signal on each receiving channel, and several sampling points within a preset time range near the sampling point corresponding to the maximum intensity value;

[0037] Perform an averaging process on the moments corresponding to the sampling point corresponding to the maximum intensity value and several sampling points within a preset time range near the sampling point corresponding to the maximum intensity value, and determine the average moment as the actual center time of the echo signal on each receiving channel.

[0038] In a second aspect, the present application also provides a calibration device for a radio frequency system. The device includes:

[0039] An acquisition module, configured to acquire the actual center time of the echo signal on each receiving channel and the theoretical center time of the echo signal;

[0040] A determination module, configured to determine the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual center time of the echo signal on each receiving channel and the theoretical center time of the echo signal;

[0041] A calibration module, configured to adjust the radio frequency transmission instruction of the radio frequency transmitting system or adjust the radio frequency reception instruction of the radio frequency receiving system to calibrate the relative delay.

[0042] In a third aspect, the present application also provides a computer device. The computer device includes a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, the method described in the first aspect above is implemented.

[0043] In a fourth aspect, the present application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, and when the computer program is executed by a processor, the method described in the first aspect above is implemented.

[0044] For the calibration method, device, computer device, and storage medium of the above radio frequency system, by obtaining the actual center time of the echo signal on each receiving channel and the theoretical center time of the echo signal, and determining the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual center time of the echo signal and the theoretical center time of the echo signal on each receiving channel, and then performing calibration on the relative delay. The above method can measure the relative delay of the radio frequency system only based on the actual center time and the theoretical center time of the echo signal. Compared with the traditional method for measuring the relative delay, it does not require complex means such as image or phase analysis. The above method is simpler and does not require introducing new hardware, greatly reducing the calibration cost. In addition, it has low requirements for the system state and no requirements for the initial value, and is more suitable for magnetic resonance systems with a parallel radio frequency transmitting system. Description of the Drawings

[0045] Figure 1 It is a schematic diagram of an application environment in an embodiment;

[0046] Figure 2 It is a schematic flowchart of a calibration method for a radio frequency system in an embodiment;

[0047] Figure 2A It is a schematic diagram of a magnetic resonance sequence provided in an embodiment;

[0048] Figure 3 For Figure 2 It is a schematic flowchart of an implementation manner of S104 in an embodiment;

[0049] Figure 4 For Figure 3 It is a schematic flowchart of an implementation manner of S201 in an embodiment;

[0050] Figure 5 For Figure 2 It is a schematic flowchart of an implementation manner of S102 in an embodiment;

[0051] Figure 6 For Figure 3 It is a schematic flowchart of another implementation manner of S201 in an embodiment;

[0052] Figure 7 For Figure 2 It is a schematic flowchart of another implementation manner of S102 in an embodiment;

[0053] Figure 7ASchematic diagram of a magnetic resonance sequence provided in an embodiment;

[0054] Figure 8 Flow schematic diagram of a calibration method for a radio frequency system in an embodiment;

[0055] Figure 9 Flow schematic diagram of a calibration method for a radio frequency system in another embodiment;

[0056] Figure 10 Internal structure diagram of a measuring device in an embodiment. Detailed implementation manners

[0057] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0058] The calibration method for the radio frequency system provided in the embodiments of the present application can be applied to an application environment as Figure 1 shown. The application environment includes: a radio frequency transmitting system 102, a radio frequency receiving system 104, and a measuring device 106. Among them, the radio frequency transmitting system 102 is mainly responsible for generating and amplifying the radio frequency waveform signal defined in the pulse sequence program to complete the excitation of tissues. The radio frequency receiving system 104 is mainly responsible for receiving the magnetic resonance signal from the magnetic resonance coil, amplifying and sampling it to complete the digital acquisition of the magnetic resonance signal. The measuring device 106 is used to measure the relative delay between the radio frequency transmitting system 102 and the radio frequency receiving system 104, and correct the relative delay by adjusting the radio frequency transmission instruction of the radio frequency transmitting system or the radio frequency reception instruction of the radio frequency receiving system. The measuring device 106 can be, but is not limited to, various personal computers, laptop computers, smart phones, tablet computers, Internet of Things devices, and portable wearable devices. The Internet of Things devices can be smart speakers, smart TVs, smart air conditioners, smart vehicle-mounted devices, etc. The portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc.

[0059] In the above application environment, since both the radio frequency (RF) transmission system 102 and the RF reception system 104 have multiple levels of subsystems and there are significant differences in terms of their structures, operating powers, number of channels, etc., the time intervals from receiving an instruction to the instruction taking effect are not exactly the same. Since all magnetic resonance imaging starts with the emission of RF pulses, undergoes a series of encodings, and ultimately aims at receiving signals, the absolute value of the instruction delay has little impact, while the relative value has a greater impact on the imaging effect. For example, if the instruction delays of both the RF transmission system 102 and the RF reception system 104 are 1 s, and the actual magnetic resonance phenomenon occurs 1 s after the instruction, but since their relative delay is 0 s, it does not affect the imaging effect. However, if the delay of the RF transmission system is 1 s and the delay of the RF reception system is 0 s, it may result in no echo generation when the RF reception system is turned on. Based on this problem, the correction method proposed in this application mainly targets the relative delay generated by the RF system. The following embodiments specifically illustrate this correction method.

[0060] In one embodiment, as Figure 2 shown, a correction method for an RF system is provided. Taking the case where this method is applied to the Figure 1 measurement device as an example, the method includes the following steps:

[0061] S101, obtaining the actual central moment of the echo signal on each receiving channel.

[0062] Among them, the echo signal is the time-domain signal on the receiving channel in the RF reception system. The actual central moment of the echo signal is the receiving moment corresponding to the center point of the echo signal on the receiving channel in the RF reception system. If the position of the center point of the echo signal corresponds to the position of the peak value of the echo signal, the actual central moment of the echo signal is also the actual peak moment of the echo signal. The actual central moment of the echo signal can be obtained by analyzing the time-domain signal on the receiving channel. In this embodiment, when the RF reception system has M RF receiving channels, the receiving moment corresponding to the waveform center point of the echo signal on each receiving channel is analyzed to obtain the actual central moment of the echo signal on each receiving channel.

[0063] S102, obtaining the theoretical central moment of the echo signal on each receiving channel.

[0064] Among them, the theoretical central moment of the echo signal is determined according to the RF sequence and the Bloch equation. Specifically, the central moment at which the echo signal appears with the maximum intensity can be calculated using the Bloch equation according to the sequence used, that is, the theoretical central moment of the echo signal.

[0065] An exemplary illustration of the above actual central moment and theoretical central moment is as follows. For example, as Figure 2ASchematic diagram of a magnetic resonance sequence, where the RF axis represents the radio frequency transmission system, the Grad axis represents the gradient system, and the ADC axis represents the radio frequency reception system. The shapes of the radio frequency pulses and echo signals shown on the RF axis are only for illustration purposes. The gradient can be on any physical axis and exists from the start to the end of the sequence. The wavy signal indicates repetition. The squares on the ADC axis represent the start and end of reception. The equivalent center time of the radio frequency pulse can be obtained by solving the Bloch equation. Denote the equivalent center time of the first radio frequency pulse as 0, and the equivalent center time interval between the first radio frequency pulse and the second radio frequency pulse as t1. According to the principle of magnetic resonance, the echo signal appears at the moment of 2t1 (the moment corresponding to point A in the figure). Align the center time of the square on the ADC axis with the moment of 2t1 when the echo signal appears, then this 2t1 is the theoretical center time of the echo signal, that is, use the center time of the square on the ADC axis as the theoretical center time of the echo signal. The reception moment corresponding to the center point of the echo signal on the ADC receiving channel of the radio frequency reception system (the moment corresponding to point B in the figure) is the actual center time of the echo signal.

[0066] S103. Determine the relative delay between the radio frequency transmission system and the radio frequency reception system according to the actual center time of the echo signal on each receiving channel and the theoretical center time of the echo signal.

[0067] When the measuring device obtains the actual center time of the echo signal on each receiving channel and the theoretical center time of the echo signal, it can further perform a difference operation on the actual center time of the echo signal and the theoretical center time of the echo signal on each receiving channel, and determine the relative delay between the radio frequency transmission system and the radio frequency reception system corresponding to each receiving channel as the obtained differences.

[0068] S104. Correct the relative delay.

[0069] When the measuring device measures the relative delay between the radio frequency transmission system and the radio frequency reception system based on the foregoing steps, it can then analyze the relative delay and select an appropriate phase correction method according to the analysis result to correct the relative delay on each receiving channel. If the relative delays corresponding to different receiving channels are different (the differences between the relative delays of the receiving channels are not significant), different correction methods can be used to correct the relative delays corresponding to each receiving channel; if the relative delays corresponding to different receiving channels are basically the same (the differences between the relative delays of the receiving channels are not significant), the same correction method can be used to correct the relative delays corresponding to each receiving channel. The phase correction methods can include at least one of methods such as adjusting commands, time-domain signal translation, and frequency-domain phase compensation.

[0070] The calibration method of the radio frequency system provided by the above embodiments obtains the actual center time of the echo signal and the theoretical center time of the echo signal on each receiving channel, and determines the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual center time of the echo signal and the theoretical center time of the echo signal on each receiving channel, and then corrects for the relative delay. The above method can measure the relative delay of the radio frequency system only based on the actual center time and the theoretical center time of the echo signal. Compared with the traditional method of measuring relative delay, it does not require complex means such as image or phase analysis. The above method is simpler and does not require the introduction of new hardware, greatly reducing the calibration cost. In addition, it has low requirements for the system state and no requirements for the initial value, and is more suitable for magnetic resonance systems with parallel radio frequency transmitting systems.

[0071] In one embodiment, a specific method for calibrating the relative delay is provided, that is, a specific implementation manner of the above S103, as Figure 3 shown, the above S103 "correct for the relative delay" includes:

[0072] S201, if the relative delay is greater than a preset delay threshold, then adjust the radio frequency transmission instruction of the radio frequency transmitting system or adjust the radio frequency reception instruction of the radio frequency receiving system to correct the relative delay.

[0073] The relative delay calibration method involved in this embodiment is by adjusting the instruction, that is, this method is adopted when it is determined that the relative delay is large. Specifically, in an actual radio frequency system, if the time taken for the radio frequency transmission instruction in the radio frequency transmitting system to take effect is ΔT TX = 1 μs, and the time taken for the radio frequency receiving system to receive the instruction and take effect is ΔT RX = 3 μs,, then the actual center time of the collected echo signal appears 2 μs earlier than the theoretical center time of the echo signal. Therefore, the relative delay ΔT relative can be calculated according to the difference between the actual center time of the collected echo signal and the theoretical center time of the echo signal, and the relative delay can be corrected by correspondingly adjusting the relative timing of the radio frequency transmission instruction of the radio frequency transmitting system or the radio frequency reception instruction of the radio frequency receiving system.

[0074] Based on the above analysis principle, in this embodiment, when the measuring device obtains the relative delay between the radio frequency transmitting system and the radio frequency receiving system, the relative delay can be further analyzed to determine whether the time taken for the instruction to be issued and take effect in the radio frequency transmitting system (denoted as: ΔT TX ) is greater than the time taken for the instruction to be issued and take effect in the radio frequency receiving system (denoted as: ΔT RX ), if ΔT TX > ΔT RX, it means that the actual center time of the echo signal is later than the theoretical center time of the echo signal. At this time, when correcting the relative delay, the RF transmission instruction can be advanced by a preset time relative to the RF reception instruction, or the RF reception instruction can be delayed by a preset time relative to the RF transmission instruction. Similarly, if ΔT TX <ΔT RX , it means that the actual center time of the echo signal is earlier than the theoretical center time of the echo signal. At this time, when correcting the relative delay, the RF transmission instruction can be delayed by a preset time relative to the RF reception instruction, or the RF reception instruction can be advanced by a preset time relative to the RF transmission instruction. The preset time is the time corresponding to the relative delay.

[0075] Optionally, the correction method is exemplified from another aspect, for example, referring to the following relationship for calculating the relative delay:

[0076] ΔT relative =ΔT TX -ΔT RX =Δt=T sampling *S offset (1);

[0077] Among them, T sampling is the time interval between two sampling points, S offset is the difference in sampling points between the actual center time of the echo signal and the theoretical center time of the echo signal. When the actual center time of the echo signal is later than the theoretical center time of the echo signal, it is recorded as a positive value. When it is a positive value, it means that ΔT TX >ΔT RX On the contrary, when the actual center time of the echo signal is earlier than the theoretical center time of the echo signal, it is recorded as a negative value. When it is a negative value, it means that ΔT TX <ΔT RX Therefore, the delay time from the start to the effectiveness of the RF receiving instruction of the RF receiving system with the RF transmitting instruction as a reference can be positive or negative. Refer to equation (1), if T sampling =1us, the actual center time of the echo signal is 3 sampling points later than the theoretical center time of the echo signal, then ΔT relative =1μs*3=3μs, at this time, the correction can be completed by advancing the RF transmission instruction by 3μs relative to other instructions, or delaying the RF reception instruction by 3μs relative to other instructions. According to the above relationship (1), when specifically measuring the relative delay between the RF transmission system and the RF reception system, the time interval between the sampling points can be reduced to improve the relative accuracy of determining the actual center time of the echo signal, thereby improving the measurement accuracy of the relative delay.

[0078] For another example, since the time-domain morphology of the echo signal is affected by many factors such as the distribution of imaging nuclides in the sample, the B0 field uniformity of the magnetic resonance system, the radiofrequency pulse waveform, the gradient linearity, and the gradient magnitude, a set of parameters is given as example parameters, which need to be adjusted according to the experimental situation: a spherical homogeneous water phantom with a diameter of 150 mm, a B0 field with the best uniformity, a radiofrequency pulse with a square waveform lasting for 1 ms, T sampling = 20 μs, Grad = 2 mT / m, t1 = 3 ms, N sampling = 201, and the sampling center time (i.e., at the 101st sampling point) is aligned with the theoretical center time of the echo signal. Then, when the echo signal appears at the 91st sampling point, it can be calculated according to the above formula (1): T relative = 20 * (101 - 91) = 200 μs. After that, the radiofrequency reception instruction in the radiofrequency reception system can be advanced by 200 μs compared with other instructions, or the radiofrequency transmission instruction in the radiofrequency transmission system can be delayed by 200 μs compared with other instructions to complete the correction through the interface.

[0079] S202. If the relative delay is not greater than the preset delay threshold, the relative delay is corrected by means of time-domain signal translation or frequency-domain phase compensation.

[0080] The relative delay correction method involved in this embodiment is to translate the signal, that is, this method is adopted when it is determined that the relative delay is small. Specifically, the measuring device can perform time-domain translation on the echo signal on the receiving channel and perform Fourier transform on the translated signal to complete the correction of the relative delay on the receiving channel; or, perform Fourier transform on the echo signal on the receiving channel and perform phase compensation on the transformed signal to complete the correction of the relative delay on the receiving channel. Optionally, the above method is a compensation method for the receiving end. Correspondingly, compensation can also be performed at the transmitting end, that is, perform time-domain translation on the radiofrequency signal on the transmitting channel and perform Fourier transform on the translated signal to complete the correction of the relative delay of the receiving channel relative to the transmitting channel.

[0081] Furthermore, a specific implementation manner of the above S201 is provided. As Figure 4 shown, the above 201 "adjust the radiofrequency transmission instruction of the radiofrequency transmission system or adjust the radiofrequency reception instruction of the radiofrequency reception system to correct the relative delay" includes:

[0082] S301. If the relative delay indicates that the instruction time of the radiofrequency reception system is greater than the instruction time of the radiofrequency transmission system, advance the sending time of the radiofrequency reception instruction of the radiofrequency reception system by the time corresponding to the relative delay relative to the sending time of the radiofrequency transmission instruction of the radiofrequency transmission system, or delay the sending time of the radiofrequency transmission instruction of the radiofrequency transmission system by the time corresponding to the relative delay relative to the sending time of the radiofrequency reception instruction of the radiofrequency reception system.

[0083] Among them, the instruction time consumption of the radio frequency receiving system represents the time from when the instruction issued by the radio frequency receiving system is sent out to when it takes effect; the instruction time consumption of the radio frequency transmitting system represents the time from when the instruction issued by the radio frequency transmitting system is sent out to when it takes effect. In this embodiment, when the measuring device obtains the relative delay between the radio frequency transmitting system and the radio frequency receiving system on each receiving channel based on the method described in S102 above, since the relative delay can be deduced and determined from the instruction time consumption of the radio frequency transmitting system and the instruction time consumption of the radio frequency receiving system, therefore, according to the relative delay, the difference between the instruction time consumption of the radio frequency receiving system and the instruction time consumption of the radio frequency transmitting system can be evaluated, and the relative delay can be corrected according to this difference later.

[0084] Exemplarily, for instance, if the relative delay indicates that the instruction time consumption of the radio frequency receiving system is greater than that of the radio frequency transmitting system, in one case, it means that the sending moment of the radio frequency receiving instruction of the radio frequency receiving system is later than the theoretically sending moment. At this time, without changing the sending moment of the radio frequency transmitting instruction of the original radio frequency transmitting system, the sending moment of the radio frequency receiving instruction of the radio frequency receiving system is advanced by the time corresponding to the relative delay relative to the sending moment of the radio frequency transmitting instruction of the radio frequency transmitting system; in another case, it means that the sending moment of the radio frequency transmitting instruction of the radio frequency transmitting system is earlier than the theoretically sending moment. At this time, without changing the sending moment of the radio frequency receiving instruction of the original radio frequency receiving system, the sending moment of the radio frequency transmitting instruction of the radio frequency transmitting system is lagged by the time corresponding to the relative delay relative to the sending moment of the radio frequency receiving instruction of the radio frequency receiving system.

[0085] S302, if the relative delay indicates that the instruction time consumption of the radio frequency receiving system is less than that of the radio frequency transmitting system, the sending moment of the radio frequency receiving instruction of the radio frequency receiving system is lagged by the time corresponding to the relative delay relative to the sending moment of the radio frequency transmitting instruction of the radio frequency transmitting system, or the sending moment of the radio frequency transmitting instruction of the radio frequency transmitting system is advanced by the time corresponding to the relative delay relative to the sending moment of the radio frequency receiving instruction of the radio frequency receiving system.

[0086] Exemplary illustration. For example, if the relative delay indicates that the instruction time of the radio frequency receiving system is less than that of the radio frequency transmitting system, in one case, it means that the issuance time of the radio frequency receiving instruction of the radio frequency receiving system is earlier than the theoretically expected issuance time. At this time, without changing the issuance time of the radio frequency transmitting instruction of the original radio frequency transmitting system, the issuance time of the radio frequency receiving instruction of the radio frequency receiving system is delayed by a time corresponding to the relative delay with respect to the issuance time of the radio frequency transmitting instruction of the radio frequency transmitting system; in another case, it means that the issuance time of the radio frequency transmitting instruction of the radio frequency transmitting system is later than the theoretically expected issuance time. At this time, without changing the issuance time of the radio frequency receiving instruction of the original radio frequency receiving system, the issuance time of the radio frequency transmitting instruction of the radio frequency transmitting system is advanced by a time corresponding to the relative delay with respect to the issuance time of the radio frequency receiving instruction of the radio frequency receiving system.

[0087] In one embodiment, an implementation manner of the above S102 is provided, as Figure 5 shown, the above S102 "determine the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual center time of the echo signal on each receiving channel and the theoretical center time of the echo signal" includes:

[0088] S401, determine the difference between the theoretical center time and the actual center time of the echo signal on each receiving channel.

[0089] When there are a preset number (such as M) of radio frequency receiving channels, based on the foregoing S101 step, obtain the theoretical center time and the actual center time of the echo signal collected on each of these M receiving channels, and calculate the difference between the theoretical center time and the actual center time of the echo signal on each receiving channel. For an exemplary illustration of the specific calculation process, reference can be made to Figure 2A the shown magnetic resonance sequence diagram. On the ADC axis, measure the actual center time of the echo signal, such as Figure 2A the time corresponding to the position of point B as shown, and at the same time, collect the theoretical center time of the echo signal, that is, the time corresponding to the center position of the square above the ADC axis, such as Figure 2A the time corresponding to the position of point A as shown, and then calculate the difference between the time corresponding to the position of point A and the time corresponding to the position of point B.

[0090] S402, calculate the relative delay of each receiving channel with respect to the target transmitting channel according to the difference between the theoretical center time and the actual center time of the echo signal on each receiving channel.

[0091] Among them, the target transmission channel is the transmission channel used during the current acquisition among all the transmission channels included in the radio frequency transmission system, and the target transmission channel can be any one of all the transmission channels. When there are a preset number (such as N) of radio frequency transmission channels, any one of the N radio frequency transmission channels (target transmission channel) can transmit the same radio frequency pulse sequence to any one of the M radio frequency receiving channels for reception. Therefore, when the measurement device determines the radio frequency sequence of the target transmission channel, it can determine the theoretical center time of the echo signal according to the radio frequency sequence of the target transmission channel. In this scenario, when calculating the difference between the theoretical center time and the actual center time of the echo signal on each receiving channel based on the method described in S301 above, the difference between the theoretical center time and the actual center time of the echo signal on each receiving channel can be directly determined as the relative delay of each receiving channel relative to the target transmission channel. It should be noted that the actual center times of the echo signals on each receiving channel are different, so the relative delays calculated for each receiving channel are also different. Subsequently, the relative delays of each receiving channel relative to the target transmission channel can be corrected separately. It should be noted that for a parallel transmission radio frequency system, one radio frequency transmission channel can be used to transmit radio frequency pulses each time to correct the relative delays of each receiving channel.

[0092] Specifically, when the measurement device corrects the relative delay corresponding to each receiving channel respectively, it can specifically execute the steps: according to the relative delay of each receiving channel relative to the target transmission channel, adjust the sending time of the radio frequency receiving instruction of each receiving channel or the sending time of the radio frequency transmission instruction of the target transmission channel respectively to correct the relative delay of each receiving channel relative to the target transmission channel.

[0093] This embodiment relates to a method for correcting the relative delay of each receiving channel according to the relative delay of each receiving channel. For the method of correcting the relative delay of each receiving channel, reference can be made to the description of the method in S103 or Figure 4 the description of the method in the embodiment. Details are not elaborated here. However, it should be noted that when correcting the relative delay by adjusting the instruction, the ways of adjusting the instruction for each receiving channel can be the same or different. For example, taking the radio frequency transmission instruction of the target transmission channel as a reference, the sending times of the radio frequency receiving instructions on all receiving channels can be adjusted to achieve the purpose of correcting the relative delay of each receiving channel relative to the target transmission channel; or, taking the radio frequency receiving instruction as a reference, the sending times of the radio frequency transmission instructions of the target transmission channels corresponding to each receiving channel can be adjusted respectively.

[0094] Optionally, when the measuring device calculates the relative delay of each receiving channel with respect to the target transmitting channel, it can further determine the difference in the relative delays between the receiving channels. If the difference in the relative delays between the receiving channels is large, for example, the difference > 1%, then the relative delay corresponding to each receiving channel is corrected by the method of the above adjustment instruction; if the difference in the relative delays between the receiving channels is small, for example, the difference < 1%, the relative delay corresponding to each receiving channel is corrected by the method of shifting the signal in the time domain and then performing Fourier transform, or by the method of performing Fourier transform and then compensating for the phase.

[0095] The method for correcting the relative delay provided in the above embodiment is implemented by separately adjusting the corresponding instructions on each receiving channel. In one embodiment, a method for uniformly adjusting the corresponding instructions on all receiving channels to achieve the correction of the relative delay is also provided, such as Figure 6 shown, that is, the above S201 "adjust the radio frequency transmission instruction of the radio frequency transmission system or adjust the radio frequency reception instruction of the radio frequency reception system to correct the relative delay" includes:

[0096] S501, calculate the average delay of the relative delays of all receiving channels with respect to the target transmitting channel.

[0097] When the radio frequency reception system has M radio frequency receiving channels, and the measuring device measures the relative delay of each receiving channel in these M radio frequency receiving channels with respect to the target transmitting channel, the relative delays of these M radio frequency receiving channels can be further averaged to obtain the average delay of the relative delays of all receiving channels with respect to the target transmitting channel.

[0098] S502, according to the average delay, uniformly adjust the issuing time of the radio frequency reception instruction of each receiving channel or the issuing time of the radio frequency transmission instruction of the target transmitting channel to correct the relative delay of each receiving channel with respect to the target transmitting channel.

[0099] When the measuring device calculates the average delay of the relative delays of all receiving channels with respect to the target transmitting channel, in one application, according to the average delay, the issuing time of the radio frequency reception instruction of each receiving channel with respect to the radio frequency transmission instruction of the target transmitting channel can be uniformly adjusted. For example, the issuing time of the radio frequency reception instruction of each receiving channel can be uniformly advanced, or the issuing time of the radio frequency reception instruction of each receiving channel can be uniformly delayed; or, in another application, according to the average delay, the issuing time of the radio frequency transmission instruction of the target transmitting channel with respect to the radio frequency reception instruction of the receiving channel can be uniformly adjusted. For example, the issuing time of the radio frequency transmission instruction of the target transmitting channel can be uniformly advanced, or the issuing time of the radio frequency transmission instruction of the target transmitting channel can be uniformly delayed.

[0100] In practical applications, when there are N radio frequency (RF) transmission channels and M RF reception channels, N repetitions can be performed. In each repetition, pulses of the same waveform are transmitted through different RF transmission channels. For the RF reception system, the respective relative delays corresponding to each reception channel can be measured, and then the timing of the RF transmission instructions can be adjusted accordingly. In the above embodiments, by repeating the measurement or averaging the relative delays on all reception channels, the signal-to-noise ratio can be improved, thereby enhancing the accuracy of the measurement device in measuring the relative delay.

[0101] Optionally, the RF reception system can also receive multiple echo signals and use the multiple echo signals to acquire multiple sets of relative delays within a repetition time TR, thereby determining the relative delay between the RF transmission system and the RF reception system. In this case, a method for measuring the relative delay of each reception channel is provided, such as Figure 7 shown, and the method includes:

[0102] S601, determining the difference between the actual center time of multiple echo signals on each reception channel and the theoretical center time of the corresponding multiple echo signals.

[0103] When there are multiple reception channels, the difference between the actual center time of multiple echo signals on each reception channel and the theoretical center time of the corresponding multiple echo signals can also be calculated based on the actual center time and the theoretical center time of the echo signals on each reception channel, so as to further determine the relative delay of each reception channel using this difference later.

[0104] S602, obtaining the average difference of the differences on each reception channel or the weighted average difference of the differences weighted by the echo signal intensity.

[0105] When the measurement device calculates the difference between the actual center time of multiple echo signals on each reception channel and the theoretical center time of the corresponding multiple echo signals, the average difference of the differences on each reception channel can further be obtained by performing a mean operation on all the differences; optionally, the measurement device can also use the echo signal intensity as the weight to perform a weighted mean operation on all the differences to obtain the weighted average difference of the differences on each reception channel weighted by the echo signal intensity.

[0106] S603, calculating the relative delay of each reception channel relative to the target transmission channel according to the average difference of the differences on each reception channel or the weighted average difference of the differences weighted by the echo signal intensity.

[0107] When the measuring device obtains the average difference of the differences on each receiving channel based on the foregoing steps, the above relationship (1) can be selected and substituted into the average difference to calculate the relative delay of each receiving channel relative to the target transmitting channel. Similarly, when the measuring device obtains the average difference of the echo signal intensity weighted differences on each receiving channel based on the foregoing steps, the above relationship (1) can also be selected and substituted into the average difference to calculate the relative delay of each receiving channel relative to the target transmitting channel.

[0108] An exemplary description of the above method is as follows. Refer to the Figure 7A schematic diagram of the magnetic resonance sequence shown in the figure. As shown in the figure, the equivalent center of the first radio frequency pulse is recorded as the 0 moment, and the equivalent center interval times of the 1-2 and 2-3 radio frequency pulses are t1 and t2 respectively. And when t2 > t1, according to the magnetic resonance principle, it can be determined that there are five echo signals appearing at 2t1, 2t1 + t2, 2t2, t1 + 2t2, and 2t1 + 2t2 respectively. After reasonably setting the radio frequency sampling interval T sampling the average difference S offset of the above 5 receiving channels, or the average difference S offset of the echo signal intensity weighted can be substituted into the above relationship (1) to calculate the relative delay ΔT relative of the 5 receiving channels.

[0109] In one embodiment, for the echo signal collected on the receiving channel in the radio frequency receiving system, since the waveform covers multiple sampling points, the actual center moment of the echo signal can be determined based on different sampling intervals and the number of sampling points. Therefore, a method for determining the actual center moment of the echo signal is provided. As Figure 8 shown in the figure, the method includes:

[0110] S701, obtain the sampling point corresponding to the maximum intensity of the echo signal on each receiving channel, and several sampling points within a preset time range near the sampling point corresponding to the maximum intensity.

[0111] Generally, the waveform of the echo signal is symmetrically distributed, and the moment corresponding to the peak value of the echo signal is the actual center moment of the echo signal. To ensure the accuracy of the actual center moment, the intensity of the echo signal at different sampling points can be used to determine the actual center moment of the echo signal. Specifically, the measuring device can first determine the sampling point corresponding to the maximum intensity of the echo signal, obtain several sampling points within a preset time range centered on the moment of this sampling point, and then determine the actual center moment of the echo signal based on the moments corresponding to these sampling points.

[0112] S702: Average the time instants corresponding to the sampling point with the maximum intensity and several sampling points within a preset time range near the sampling point with the maximum intensity, and determine the obtained average time instant as the actual central time instant of the echo signal on each receiving channel.

[0113] When the measuring device obtains the sampling point corresponding to the maximum intensity of the echo signal on each receiving channel and several sampling points within a preset time range near the sampling point corresponding to the maximum intensity, the time instant of the sampling point corresponding to the maximum intensity and the time instants of several sampling points within the preset time range near this sampling point can be further determined. Then, perform a mean operation on the time instants of these sampling points to obtain the average time instant. Finally, set this average time instant as the actual central time instant of the echo signal on each receiving channel. Determining the actual central time instant of the echo signal through a mean operation can improve the signal-to-noise ratio and thereby improve the measurement accuracy.

[0114] In one embodiment, in the gradient system corresponding to the radio frequency transmitting system and the radio frequency receiving system, it is set that the gradient exists from the start to the end of the radio frequency pulse sequence emitted by the radio frequency transmitting system, and the gradient ramp-up time is greater than a preset time threshold from the start time of the first radio frequency pulse sequence. The preset time threshold can be determined in advance by the measuring device. For example, referring to Figure 2A In the shown magnetic resonance sequence diagram, in the gradient system, the gradient exists from the start to the end of the sequence. Preferably, the gradient ramp-up time is more than 2 s away from the first radio frequency pulse sequence. Here, the preset time threshold is 2 s as the optimal value.

[0115] In addition, it should be noted that during the measurement and calibration processes described in any of the above embodiments, for the gradient system, the continuously existing gradient also serves as the dephasing and rephasing gradients to adjust the width of the echo signal in the time domain. The FID generated by the radio frequency excitation is quickly attenuated without affecting the subsequent measurement. At the echo time, its dephasing effect is cancelled, so it does not affect the intensity of the required echo signal. When its intensity is large, the dephasing of the FID, the rephasing and dephasing of the echo become faster, and it can be found that the echo appears as a thin peak; when its intensity is medium, the change process of the intensity and phase of the echo with time can be seen; when its intensity is weak, the collected signal is mixed with FID and spin echo. By controlling the gradient intensity, the type of the collected signal, its morphology in the time domain, and its intensity can be controlled. At the same time, the continuously existing gradient avoids the influence of eddy currents on the signal during gradient switching, reducing the requirements of this method on the system. Moreover, by appropriately reducing the gradient intensity, the excited slice thickness can be increased, thereby increasing the signal intensity and the broadband of the echo in the time domain, so as to improve the relative accuracy of determining the actual central time instant (peak value) of the echo signal.

[0116] It should be understood that although the steps in the flowcharts involved in the above-described embodiments are sequentially shown according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-described embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same moment, but can be executed at different moments, and the execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or steps or stages in other steps.

[0117] Based on the same inventive concept, an embodiment of the present application further provides a calibration device for a radio frequency system for implementing the calibration method of the radio frequency system involved above. The solution provided by this device to solve the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the following calibration device for a radio frequency system can refer to the limitations on the calibration method of the radio frequency system in the above text, and will not be repeated here.

[0118] In one embodiment, as Figure 8 shown, a calibration device for a radio frequency system is provided, including:

[0119] A first acquisition module 11, configured to acquire the actual center moment of the echo signal on each receiving channel;

[0120] A second acquisition module 12, configured to acquire the theoretical center moment of the echo signal on each receiving channel;

[0121] A determination module 13, configured to determine the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual center moment of the echo signal on each receiving channel and the theoretical center moment of the echo signal;

[0122] A calibration module 14, configured to perform calibration for the relative delay.

[0123] Each module in the above calibration device for a radio frequency system can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in the processor in the computer device in hardware form or be independent of it, or can be stored in the memory in the computer device in software form, so that the processor can call and execute the operations corresponding to the above respective modules.

[0124] In one embodiment, a measurement device is provided. This measurement device can be a server, and its internal structure diagram can be as Figure 10As shown. The measurement device includes a processor, a memory, and a network interface connected through a system bus. Among them, the processor of the measurement device is used to provide computing and control capabilities. The memory of the measurement device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the measurement device is used to store radio frequency data. The network interface of the measurement device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements a calibration method for a radio frequency system.

[0125] Those skilled in the art can understand that Figure 10 the structure shown in is only a block diagram of some structures related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have a different component layout.

[0126] In one embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, the following steps are implemented:

[0127] Obtain the actual center time of the echo signal on each receiving channel;

[0128] Obtain the theoretical center time of the echo signal on each of the receiving channels;

[0129] Determine the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual center time of the echo signal and the theoretical center time of the echo signal on each receiving channel;

[0130] Perform calibration for the relative delay.

[0131] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by the processor, the following steps are implemented:

[0132] Obtain the actual center time of the echo signal on each receiving channel;

[0133] Obtain the theoretical center time of the echo signal on each of the receiving channels;

[0134] Determine the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual center time of the echo signal and the theoretical center time of the echo signal on each receiving channel;

[0135] Perform calibration for the relative delay.

[0136] In one embodiment, a computer program product is provided, including a computer program which, when executed by a processor, implements the following steps:

[0137] Obtain the actual center time of the echo signal on each receiving channel;

[0138] Obtain the theoretical center time of the echo signal on each of the receiving channels;

[0139] Determine the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual center time of the echo signal on each receiving channel and the theoretical center time of the echo signal;

[0140] Perform correction for the relative delay.

[0141] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memories. Non-volatile memories can include read-only memory (ROM), magnetic tapes, floppy disks, flash memories, optical memories, high-density embedded non-volatile memories, resistive random access memories (ReRAM), magnetoresistive random access memories (MRAM), ferroelectric random access memories (FRAM), phase change memories (PCM), graphene memories, etc. Volatile memories can include random access memory (RAM) or external cache memories, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in the present application can be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., without limitation.

[0142] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0143] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A calibration method for a radio frequency system, characterized in that The method includes: Obtaining the actual central moment of the echo signal on each receiving channel; the echo signal is a time-domain signal on the receiving channel in the radio frequency receiving system; Obtaining the theoretical central moment of the echo signal on each of the receiving channels; Determining the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual central moment and the theoretical central moment of the echo signal on each receiving channel; If the relative delay is greater than a preset delay threshold, adjusting the radio frequency transmission instruction of the radio frequency transmitting system or adjusting the radio frequency reception instruction of the radio frequency receiving system to correct the relative delay; If the relative delay is not greater than the preset delay threshold, correcting the relative delay by means of time-domain signal translation or frequency-domain phase compensation.

2. The method according to claim 1, wherein The determining the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual central moment and the theoretical central moment of the echo signal on each receiving channel includes: Determining the difference between the theoretical central moment and the actual central moment of the echo signal on each of the receiving channels; Calculating the relative delay of each receiving channel relative to the target transmitting channel according to the difference between the theoretical central moment and the actual central moment of the echo signal on each of the receiving channels; the target transmitting channel is the transmitting channel used during the current acquisition among all the transmitting channels included in the radio frequency transmitting system.

3. The method according to claim 2, wherein The adjusting the radio frequency transmission instruction of the radio frequency transmitting system or adjusting the radio frequency reception instruction of the radio frequency receiving system to correct the relative delay includes: Respectively adjusting the sending moment of the radio frequency reception instruction of each receiving channel or the sending moment of the radio frequency transmission instruction of the target transmitting channel according to the relative delay of each receiving channel relative to the target transmitting channel to correct the relative delay of each receiving channel relative to the target transmitting channel.

4. The method according to claim 2, wherein The adjusting the radio frequency transmission instruction of the radio frequency transmitting system or adjusting the radio frequency reception instruction of the radio frequency receiving system to correct the relative delay includes: Calculating the average delay of the relative delays of all receiving channels relative to the target transmitting channel; Uniformly adjusting the sending moment of the radio frequency reception instruction of each receiving channel or the sending moment of the radio frequency transmission instruction of the target transmitting channel according to the average delay to correct the relative delay of each receiving channel relative to the target transmitting channel.

5. The method according to claim 2, characterized in that If the radio frequency receiving system receives multiple echo signals, the determining the relative delay between the radio frequency transmitting system and the radio frequency receiving system according to the actual central moment and the theoretical central moment of the echo signal on each receiving channel includes: Determining the differences between the actual central moments of the multiple echo signals on each receiving channel and the corresponding theoretical central moments of the multiple echo signals; Obtaining the average difference of the differences on each receiving channel or the weighted average difference of the echo signal intensities of the differences. Calculate the relative delay of each receiving channel relative to the target transmitting channel according to the average difference of the differences on each receiving channel or the average difference weighted by the echo signal intensity of the differences.

6. The method according to claim 2, wherein Adjusting the RF transmission instruction of the RF transmission system or adjusting the RF reception instruction of the RF reception system to correct the relative delay includes: If the relative delay indicates that the instruction time of the RF reception system is greater than the instruction time of the RF transmission system, advance the sending time of the RF reception instruction of the RF reception system relative to the sending time of the RF transmission instruction of the RF transmission system by the time corresponding to the relative delay, or delay the sending time of the RF transmission instruction of the RF transmission system relative to the sending time of the RF reception instruction of the RF reception system by the time corresponding to the relative delay; If the relative delay indicates that the instruction time of the RF reception system is less than the instruction time of the RF transmission system, delay the sending time of the RF reception instruction of the RF reception system relative to the sending time of the RF transmission instruction of the RF transmission system by the time corresponding to the relative delay, or advance the sending time of the RF transmission instruction of the RF transmission system relative to the sending time of the RF reception instruction of the RF reception system by the time corresponding to the relative delay.

7. The method according to claim 1, characterized in that, Correcting the relative delay by means of time-domain signal translation or frequency-domain phase compensation includes: Perform time-domain translation on the echo signal on the receiving channel, and perform Fourier transform on the translated signal to complete the correction of the relative delay on the receiving channel; Alternatively, perform Fourier transform on the echo signal on the receiving channel, and perform phase compensation on the transformed signal to complete the correction of the relative delay on the receiving channel.

8. The method according to claim 1, wherein Correcting the relative delay by means of time-domain signal translation includes: Perform time-domain translation on the RF signal on the transmitting channel, and perform Fourier transform on the translated signal to complete the correction of the relative delay on the receiving channel.

9. The method according to claim 1, characterized in that In the gradient system corresponding to the RF transmission system and the RF reception system, set the gradient to exist from the start to the end of the RF pulse sequence sent by the RF transmission system, and the gradient rise time is greater than a preset time threshold from the start time of the first RF pulse sequence.

10. The method according to claim 1, wherein Obtaining the actual center time of the echo signal on each receiving channel includes: Obtain the sampling point corresponding to the maximum intensity of the echo signal on each receiving channel, and several sampling points within a preset time range near the sampling point corresponding to the maximum intensity; Average the times corresponding to the sampling point corresponding to the maximum intensity and several sampling points within a preset time range near the sampling point corresponding to the maximum intensity, and determine the obtained average time as the actual center time of the echo signal on each receiving channel.

11. A calibration device for a radio frequency system, characterized in that, The device includes: A first acquisition module for acquiring the actual center time of the echo signal on each receiving channel; the echo signal is a time-domain signal on the receiving channel in the RF reception system. A second acquisition module, configured to acquire the theoretical center time of the echo signal on each receiving channel; A determination module, configured to determine the relative delay between the RF transmission system and the RF reception system according to the actual center time of the echo signal on each receiving channel and the theoretical center time of the echo signal; A correction module, configured to, when the relative delay is greater than a preset delay threshold, adjust the RF transmission instruction of the RF transmission system or adjust the RF reception instruction of the RF reception system to correct the relative delay; when the relative delay is not greater than the preset delay threshold, correct the relative delay by means of time-domain signal translation or frequency-domain phase compensation.

12. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, the steps of the method according to any one of claims 1 to 10 are implemented.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 10 are implemented.

Images