A magnetic resonance radio frequency safety detection method and a magnetic resonance system

Abstract

The application provides a magnetic resonance radio frequency safety detection method and a magnetic resonance system, comprising: a magnetic resonance device, wherein the magnetic resonance device comprises a radio frequency power source, a transmitting unit, a receiving unit and a control unit; the control unit is electrically connected with the radio frequency power source, the transmitting unit and the receiving unit respectively; the control unit sends a control instruction to the transmitting unit to make the transmitting unit emit a radio frequency pulse signal to a patient at a specified position; the control unit also sends a control instruction to the receiving unit to make the receiving unit collect an electric field response signal of different body parts of the patient after the radio frequency pulse signal is applied and feed back to the control unit; compared with a traditional detection method, the magnetic resonance radio frequency safety detection system uses a preset sensitivity distribution matrix algorithm and calculates a specific absorption rate of different body parts of the patient based on a human body electric field value, thereby significantly improving the accuracy and authenticity of the detection result of the specific absorption rate of the human body.

Description

Technical Field

[0001] This invention relates to the technical field of magnetic resonance radio frequency detection, and in particular to a magnetic resonance radio frequency safety detection method and magnetic resonance system. Background Technology

[0002] Magnetic resonance imaging (MRI) has become an important tool in modern clinical diagnosis. Radiofrequency (RF) coils emit RF pulses into the human body to excite protons, causing them to rotate and resonate. SAR, or Specific Absorption Rate, measures the rate at which the human body absorbs energy when exposed to an MRI scan in a radiofrequency electromagnetic field. A higher SAR value indicates a greater impact on the body. The unit is W / kg. The significance of SAR values ​​is to ensure the safety of MRI examinations, and strict international regulations govern SAR values ​​for MRI scans.

[0003] Currently, existing methods for detecting human specific absorption rate (SPR) have the following technical problems: 1. Measurement error exists: Existing detection methods usually use theoretical coils and human body models, which differ from actual models. Therefore, the simulated SPR value and the actual SPR value will introduce errors. In addition, online monitoring methods can only monitor the whole-body SPR value. The local SPR value is obtained by using the scaling factor between the simulated local SPR value and the whole-body SPR value, which will also introduce measurement errors. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the technical problem to be solved by the present invention is to provide a magnetic resonance radio frequency safety detection method and magnetic resonance system, so as to solve the problem of measurement error in the existing methods for detecting human body specific absorption rate.

[0005] To achieve the above objectives, the present invention provides a magnetic resonance radio frequency security detection system, comprising:

[0006] A magnetic resonance imaging (MRI) device, comprising: a radio frequency power source, a transmitting unit, a receiving unit, and a control unit; the control unit is connected to the radio frequency power source, the transmitting unit, and the receiving unit respectively.

[0007] The control unit sends control commands to the transmitting unit to cause the transmitting unit to transmit radio frequency pulse signals to the patient at a designated location; the control unit also sends control commands to the receiving unit to cause the receiving unit to collect electric field response signals of different body parts of the patient after the radio frequency pulse signals are applied and feed them back to the control unit.

[0008] A computer device electrically connected to the control unit; the computer device receives electric field response signals from different body parts of the patient from the control unit, and obtains the corresponding human body electric field value from the electric field response signals; using a preset sensitivity distribution matrix algorithm, and based on the human body electric field value, the specific absorption rate of different body parts of the patient is calculated.

[0009] As a preferred approach, the sensitivity distribution matrix algorithm is used to characterize the specific absorbance of different body parts of the patient, obtained by integrating within the volume enclosed by a three-dimensional mesh model of different body parts. Traditional specific absorbance calculation methods (such as point estimation based on the assumption of a homogeneous medium or simplified geometric models) often ignore the complex three-dimensional structure of human tissues (such as organ shapes, fat / muscle layering, bone penetration, etc.), leading to estimation errors in local energy absorption. The three-dimensional mesh model divides the patient's body into numerous tiny volumetric units (voxels), each of which can independently define its electrical properties (such as dielectric constant and conductivity) and geometric coordinates. When the sensitivity distribution matrix algorithm performs volume integration based on this three-dimensional mesh, it can calculate the absorbed radio frequency power for each voxel and then sum them to obtain the total specific absorbance of the target site. This "infinite element integration" method avoids measurement errors caused by blurred tissue boundaries or simplified models, significantly improving the spatial resolution and numerical accuracy of specific absorbance. Furthermore, when the sensitivity distribution matrix algorithm is integrated based on this model, it can accurately reflect the actual distribution and electrical property differences of individual tissues, eliminate the systematic errors brought about by the standard model, and realize the individualized specific absorption rate calculation of "one person, one model", which is more in line with the actual clinical needs.

[0010] As a more preferred method, the sensitivity distribution matrix algorithm is calculated as follows:

[0011] ;in, Indicates human tissue in Specific absorption rate at a point; Indicates human tissue in The electrical conductivity at a point; Indicates human tissue in Point density; Indicates all coil channels in The electric field is a complex vector at a point, and V represents the volume enclosed by the three-dimensional mesh model of different body parts of the patient. Because the electric field is a complex vector... The spatial distribution of the excitation from each coil channel is formed by the superposition of their respective excitations, and is influenced by a combination of factors including coil design, patient position, and tissue dielectric properties. This is achieved through explicit coupling. , and These three parameters allow the algorithm to accurately reflect the interaction between different tissue characteristics and the electromagnetic environment. For example, in the fat layer ( Low, Even with a high electric field strength |E|, the specific absorption rate may be lower than that of the muscle layer (small). high, Large); while near the bone tissue ( Extremely low but (High), the electric field may be reflected due to dielectric mismatch, leading to local |E| abnormalities, which in turn affect the specific absorption rate distribution. This explicit expression of multiple parameters enables the model to more realistically simulate the electromagnetic response characteristics of biological tissues, significantly improving its adaptability to different patient sites (such as: head, neck, chest, abdomen, thigh, knee, etc.).

[0012] As a more preferred method, the calculation method of the sensitivity distribution matrix algorithm further includes:

[0013]

[0014] Among them, in the formula for: ;in The matrix is ​​n The positive definite matrix is ​​defined as the sensitivity matrix; Indicates human tissue in The electrical conductivity at a point; Indicates human tissue in Point density; Let be the complex vector of the conjugate electric field generated by the i-th channel at position r under unit excitation. This represents the transpose of the complex vector of the conjugate electric field generated at position r. This represents the radio frequency shim parameters. The complex electric field vector... This is the weighted sum of the complex electric field vectors generated by multiple channel coils at position r; its calculation formula is: (r) ;in Let be the excitation coefficient of the i-th channel coil. (r) is the complex electric field vector generated by the i-th channel at position r under unit excitation. The specific testing steps are as follows: Position the patient's head in the water phantom at the geometric center of the MRI scanner's transmitting coil to ensure the spatial position for subsequent electric field measurements; control the radio frequency power source to emit a preset power signal CH1, driving port 1 of the MRI scanner's radio frequency coil; simultaneously, use an electric field probe to measure the electric field at the phantom's spatial position. A robotic arm positions the probe point-by-point to thousands of preset measurement points inside the water phantom, collecting the electric field amplitude and phase information at each measurement point, recorded as the electric field value E1 corresponding to that port; sequentially control the radio frequency power source to emit power signals CH2, CH3…CHn (n≥2), driving ports 2 to n of the MRI scanner's radio frequency coil respectively. Repeat the probe positioning and electric field measurement process for each port, sequentially obtaining the electric field values ​​E2, E3…En corresponding to ports 2 to n, ultimately obtaining a full-range electric field measurement dataset {E1, E2, ..., En} for n coil ports; based on the full-range electric field values ​​{E1, E2, ..., En} obtained in the above steps, calculate the actual specific absorption rate of different body parts of the patient using the sensitivity distribution matrix calculation formula.

[0015] As a more preferred embodiment, the magnetic resonance imaging device further includes: a magnet, a gradient coil, a radio frequency transmitting coil, and a receiving coil; wherein, the magnet is used to generate a main magnetic field, the gradient coil is used to generate a gradient magnetic field to spatially encode the imaging area, the radio frequency transmitting coil is used to transmit radio frequency pulses to the human body under the drive of the radio frequency power source, and the receiving coil is used to collect electric field response signals generated by radio frequency pulse excitation in different parts of the human body. Magnetic resonance imaging (MRI) equipment includes a magnet, gradient coils, an RF transmitting coil, and a receiving coil. An RF power source drives the gradient coils (adjusting the gradient field strength and time via a current controller); the transmitting unit drives the RF transmitting coil (generating a specific waveform via an RF amplifier); the receiving unit connects to the receiving coil (processing the signal via a preamplifier and an analog-to-digital converter); and the control unit drives the magnet power supply (maintaining a stable main magnetic field), the gradient coil timing, the transmitting coil waveform, and the receiving coil sampling. This clear mapping relationship makes system troubleshooting and maintenance more efficient (e.g., in cases of abnormal specific absorption rate, it can quickly pinpoint whether the problem lies with unstable gradient coil current or abnormal transmitting coil power). Furthermore, when replacing the magnet with one of higher field strength or a higher density receiving coil array, only the corresponding module's drive needs adjustment, without needing to reconstruct the entire system. This improves the overall system's adaptability and flexibility, facilitating installation and subsequent maintenance.

[0016] As a more preferred embodiment, the gradient coil is a hollow cylinder placed inside the magnet. The gradient coil receives power from the radio frequency power source to generate a gradient magnetic field. Since the strength of the gradient magnetic field is directly related to the number of turns, current density, and geometry of the coil, setting the gradient coil as a hollow cylinder structure optimizes the current path. The winding method of the cylindrical coil (such as uniformly distributing the windings along the circumference) allows the current to form a more uniform magnetic field gradient in space. For example, when the Z-axis gradient coil (along the long axis of the magnet) is wound symmetrically in a cylinder, the linearity of the magnetic field gradient generated by the current in the examination area (the patient's location) is better, avoiding the focus position shift of the radio frequency pulse caused by gradient nonlinearity. In addition, the hollow structure shortens the average radius of the coil (reduces the current loop length). Under the same current output from the radio frequency power source, the coil's resistance loss is reduced, which helps to improve power utilization, reduce the heat load of the power source, and extend the service life of the equipment.

[0017] As a preferred approach, the main magnetic field strength generated by the magnet is 3.0T~7.0T. The main magnetic field strength directly affects the frequency of the radio frequency pulse. Within the 3.0T~7.0T range, as the radio frequency increases, the dielectric constant and conductivity of the tissue change more significantly with frequency. The electric field response signal acquired by the receiving unit can more clearly reflect the energy absorption characteristics of different body parts of the patient. Based on this, the specific absorption rate calculated by the computer equipment is more accurate, avoiding the problems of missed detections or measurement errors caused by signal ambiguity at low field strengths, thus improving the accuracy of the measurement results. Furthermore, at high field strengths, the gradient field switching rate of the radio frequency power source is faster (gradient field strength is positively correlated with the main magnetic field strength), thereby achieving a smaller spatial resolution. The 3.0T~7.0T main magnetic field can accurately locate different body parts of the patient. Combined with the local electric field response signal acquired by the receiving unit, the computer equipment can calculate the specific absorption rate of the human body by part (rather than the overall average) using a sensitivity distribution matrix algorithm, ensuring more realistic detection results.

[0018] As a preferred approach, the magnetic resonance imaging (MRI) device also includes an electric field probe used to measure the electric field vectors of different body parts in three-dimensional space. When radiofrequency electromagnetic fields propagate within the body, the distribution of electric field vectors exhibits significant spatial anisotropy: the electric fields of different body parts may have amplitude and phase differences in the x, y, and z directions (e.g., the electric field direction is concentrated in the near-field region, while it tends to approximate a plane wave in the far-field region). Traditional single-directional or scalar electric field measurements (measuring only |E|) lose directional information, causing the specific absorption rate meter to ignore the spatial coupling effect of the electric field vector during calculation. However, direct measurement of the three-dimensional electric field vector using an electric field probe can fully capture the spatial distribution characteristics of the electric field in each body part (e.g., the direction of electric field lines, the direction of maximum field strength), and combined with the dielectric anisotropy of different body parts, makes the specific absorption rate calculation results more accurate. Furthermore, MRI scans often involve multiple body parts (e.g., head and neck, chest and abdomen, limbs), and the geometry and electromagnetic properties of different parts vary significantly, resulting in different electric field distribution patterns. Traditional electric field measurements at fixed locations or in single areas cannot meet the detection requirements. The electric field probe of this magnetic resonance imaging device can be flexibly moved to any part of the patient's body (such as the arm, abdomen, or back) through three-dimensional spatial positioning (e.g., driven by a robotic arm) and the three-dimensional electric field vector can be measured at each location. It can dynamically adjust the measurement position of the probe to meet different clinical needs and evaluate the actual specific absorption rate of the current scanning site in real time, avoiding detection failure caused by site switching.

[0019] As a more preferred approach, the computer device of the magnetic resonance radio frequency safety detection system includes the following method: sending a radio frequency control signal to the control unit; the control unit receiving instructions from the computer device and issuing control instructions to the transmitting unit to transmit radio frequency pulse signals to a patient at a designated location; the control unit also sending control instructions to the receiving unit to collect electric field response signals of different body parts of the patient after the application of the radio frequency pulse signals and feeding them back to the control unit; receiving the electric field response signals of different body parts of the patient from the control unit and obtaining the corresponding human body electric field values ​​from the electric field response signals; and calculating the specific absorption rate of different body parts of the patient based on the human body electric field values ​​using a preset sensitivity distribution matrix algorithm. The computer device can monitor the specific absorption rate calculation results in real time through closed-loop control and adjust the radio frequency control signal in reverse (e.g., when the specific absorption rate of a certain part is detected to be close to a threshold, the control unit is immediately instructed to reduce the transmission power or shorten the pulse time), forming a dynamic optimization mechanism of "monitoring-feedback-adjustment," which helps to improve the safety and efficiency of magnetic resonance radio frequency detection.

[0020] As a more preferred approach, a computer device includes a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the magnetic resonance radio frequency safety detection method. The modular design of the computer device (processor + memory + program) works in conjunction with other components of the magnetic resonance equipment (such as the transmitting unit and receiving unit): if the processor or memory fails, only the entire computer device needs to be replaced, without disassembling other modules of the magnetic resonance equipment, thus reducing maintenance time and costs.

[0021] As described above, the magnetic resonance radio frequency security detection method and magnetic resonance system of the present invention have the following beneficial effects: When in use, the magnetic resonance radio frequency security detection method and magnetic resonance system of the present invention...

[0022] The control unit controls the transmitting unit to transmit radio frequency pulses to a designated location, and simultaneously controls the receiving unit to collect electric field response signals from different parts of the patient's body (directly reflecting the distribution of electromagnetic fields within the tissue). The computer equipment then calculates the specific absorption rate based on the electric field value, realizing real-time, dynamic, and site-specific monitoring of radio frequency energy absorption. It can provide timely warnings when the specific absorption rate approaches or exceeds the safety threshold, significantly improving the safety of MRI examinations.

[0023] The computer equipment uses a "pre-defined sensitivity distribution matrix algorithm" to calculate the specific absorptivity. Compared to traditional detection methods (such as point estimation based on the assumption of a homogeneous medium or simplified geometric models), this method results in some deviations in the calculation results. The sensitivity distribution matrix algorithm, based on this three-dimensional grid, performs volume integration, calculating the absorbed radio frequency power for each voxel and then summing them to obtain the total specific absorptivity of the target area. This "infinite element integration" method avoids the measurement error problems caused by blurred tissue boundaries or simplified models, significantly improving the accuracy and realism of the specific absorptivity calculation. Attached Figure Description

[0024] Figure 1 The diagram shows the overall structure of the magnetic resonance device of the magnetic resonance radio frequency security detection method and magnetic resonance system of the present invention.

[0025] Figure 2 The diagram shows a schematic of the electric field measurement process of a magnetic resonance radio frequency security detection method and a magnetic resonance system according to the present invention.

[0026] Figure 3 The diagram shows the operation flow of a magnetic resonance radio frequency security detection method and magnetic resonance system according to the present invention.

[0027] Figure 4 The diagram shows the operation flow of a computer device for a magnetic resonance radio frequency security detection method and magnetic resonance system according to the present invention.

[0028] Figure 5 The diagram shown is a schematic diagram of the computer device operation process of a magnetic resonance radio frequency security detection method and magnetic resonance system according to the present invention.

[0029] Component designation explanation

[0030] 1 Magnetic Resonance Equipment 101 RF power source 102 Transmission unit 103 Receiving unit 104 Control Unit 105 magnet 106 gradient coil 107 RF transmitting coil 108 receiving coil 2 Computer equipment Detailed Implementation

[0031] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0032] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation of the invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the disclosed technical content. The following detailed description should not be considered restrictive, and the scope of the embodiments of this application is limited only by the claims of the published patents. The terminology used herein is for describing specific embodiments only and is not intended to limit the application. Spatial terms such as "upper," "lower," "left," "right," "below," "below," "lower part," "above," "upper part," etc., may be used in the text to illustrate the relationship between one element or feature shown in the figures and another element or feature.

[0033] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," and "holding" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] Furthermore, as used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context indicates otherwise. It should be further understood that the terms “comprising,” “including,” indicate the presence of the stated feature, operation, element, component, item, kind, and / or group, but do not preclude the presence, occurrence, or addition of one or more other features, operations, elements, components, items, kinds, and / or groups. The terms “or” and “and / or” as used herein are interpreted as inclusive, or mean any one or any combination thereof. Thus, “A, B, or C” or “A, B, and / or C” means “any one of: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition arise only when combinations of elements, functions, or operations are inherently mutually exclusive in some manner.

[0035] Before providing a further detailed description of the present invention, the nouns and terms used in the embodiments of the present invention are explained, and the nouns and terms used in the embodiments of the present invention are subject to the following interpretations:

[0036] <1> Specific absorption rate: It is a key indicator for measuring the rate at which human tissue absorbs electromagnetic radiation energy, and is mainly used to assess the potential impact of radio frequency devices on human health.

[0037] <2> Magnetic resonance imaging equipment: It is a medical imaging device based on the principle of nuclear magnetic resonance. It generates high-resolution anatomical and functional images by detecting the resonance signals of hydrogen nuclei (protons) in the human body in a strong magnetic field, and is used for disease diagnosis and clinical treatment planning.

[0038] <3> Sensitivity distribution matrix algorithm: It is a matrix tool used to describe the response capability of a system or sensor to a target physical quantity (such as signal, field strength, concentration, etc.) at different locations / states.

[0039] <4> Total specific absorption rate: Total specific absorptivity is used to describe the electromagnetic radiation power absorbed per unit mass of biological tissue. It reflects the potential thermal effects of electromagnetic radiation on biological tissue.

[0040] <5> Electrical conductivity: Electrical conductivity is a physical quantity that describes a material's ability to conduct electricity, reflecting the ease with which charges (usually free electrons or ions) move in a directional manner within the material.

[0041] <6> Complex vector of electric field: The complex electric field vector is a mathematical tool in electromagnetism used to describe time-varying electric fields, especially in frequency domain analysis (such as sinusoidal steady-state electromagnetic fields). It simplifies the calculation of sinusoidal electric fields through complex form, decomposing the periodically changing electric field into amplitude and phase information, which facilitates the analysis of problems such as wave interference, reflection, refraction, and energy transfer.

[0042] <7> Conjugate electric field complex vector: The conjugate electric field complex vector is the complex conjugate vector corresponding to the electric field complex vector. Mathematically, it is obtained by taking the complex conjugate of each component of the electric field complex vector.

[0043] <8> RF power source: It typically refers to an energy or excitation device whose output power is distributed in a gradient (continuously changing) with a certain variable (such as location, time, load or other parameters).

[0044] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the invention.

[0045] like Figures 1 to 5 As shown, the present invention provides a magnetic resonance radio frequency security detection system, comprising:

[0046] A magnetic resonance imaging (MRI) device 1 includes: a radio frequency power source 101, a transmitting unit 102, a receiving unit 103, and a control unit 104; the control unit 104 is connected to the radio frequency power source 101, the transmitting unit 102, and the receiving unit 103 respectively.

[0047] The magnetic resonance imaging device 1 also includes a magnet 105, a gradient coil 106, a radio frequency transmitting coil 107, and a receiving coil 108. The magnet 105 generates a main magnetic field. The gradient coil 106 is connected to the radio frequency power source 101 and generates a gradient magnetic field to spatially encode the imaging area. The radio frequency transmitting coil 107 is connected to the transmitting unit 102 and transmits radio frequency pulses to the human body under the drive of the radio frequency power source 101. The receiving coil 108 is connected to the receiving unit 103 and collects electric field response signals generated by radio frequency pulse excitation at different parts of the human body. RF power source 101 drives gradient coil 106; transmitting unit 102 drives RF transmitting coil 107; receiving unit 103 is connected to receiving coil 108; control unit 104 drives magnet 105 power supply to maintain main magnetic field stability, gradient coil 106 timing, transmitting coil waveform and receiving coil 108 sampling; this clear mapping relationship makes system fault diagnosis and maintenance more efficient (e.g., when the specific absorption rate is abnormal, it can quickly locate whether the current of gradient coil 106 is unstable or the power of transmitting coil is abnormal).

[0048] The control unit 104 sends control commands to the transmitting unit 102 to cause the transmitting unit 102 to transmit radio frequency pulse signals to the patient at a designated location; the control unit 104 also sends control commands to the receiving unit 103 to cause the receiving unit 103 to collect electric field response signals of different body parts of the patient after the radio frequency pulse signals are applied and feed them back to the control unit 104.

[0049] Computer device 2 is electrically connected to control unit 104; computer device 2 receives electric field response signals from different body parts of the patient from control unit 104 and obtains the corresponding human body electric field value from the electric field response signals; using a preset sensitivity distribution matrix algorithm, the specific absorption rate of different body parts of the patient is calculated based on the human body electric field value.

[0050] In some embodiments of the present invention, such as Figure 1 and Figure 2 As shown, the sensitivity distribution matrix algorithm is used to characterize the specific absorbance of different body parts of the patient, obtained by integrating within the volume enclosed by a three-dimensional mesh model of different body parts. Traditional specific absorbance calculation methods (such as point estimation based on the assumption of a homogeneous medium or simplified geometric models) often ignore the complex three-dimensional structure of human tissues (such as organ shapes, fat / muscle layering, bone penetration, etc.), leading to estimation errors in local energy absorption. The three-dimensional mesh model divides the patient's body into numerous tiny volumetric units (voxels), each of which can independently define its electrical properties (such as dielectric constant and conductivity) and geometric coordinates. When the sensitivity distribution matrix algorithm performs volume integration based on this three-dimensional mesh, it can calculate the absorbed radio frequency power for each voxel and then sum them to obtain the total specific absorbance of the target site. This "infinite element integration" method avoids the measurement error caused by blurred tissue boundaries or simplified models, significantly improving the spatial resolution and numerical accuracy of specific absorbance. Furthermore, when the sensitivity distribution matrix algorithm is integrated based on this model, it can accurately reflect the actual distribution and electrical characteristic differences of individual tissues, eliminate the systematic errors brought about by the standard model, and realize personalized SAR calculation with "one person, one model", which is more in line with actual clinical needs.

[0051] In some embodiments of the present invention, such as Figure 2 As shown, the calculation method of the sensitivity distribution matrix algorithm is as follows: ;in, Indicates human tissue in Specific absorption rate at a point; Indicates human tissue in The electrical conductivity at a point; Indicates human tissue in Point density; Indicates all coil channels in The electric field is a complex vector at a point, and V represents the volume enclosed by the three-dimensional mesh model of different body parts of the patient. Because the electric field is a complex vector... The spatial distribution of the excitation from each coil channel is formed by the superposition of their respective excitations, and is influenced by a combination of factors including coil design, patient position, and tissue dielectric properties. This is achieved through explicit coupling. , and These three parameters allow the algorithm to accurately reflect the interaction between different tissue characteristics and the electromagnetic environment. For example, in the fat layer ( Low, Even with a high electric field strength |E|, the specific absorption rate may be lower than that of the muscle layer (small). high, Large); while near the bone tissue ( Extremely low but (High), the electric field may be reflected due to dielectric mismatch, leading to local |E| abnormalities, which in turn affect the specific absorption rate distribution. This explicit expression of multiple parameters enables the model to more realistically simulate the electromagnetic response characteristics of biological tissues, significantly improving its adaptability to different patient sites (such as: head, neck, chest, abdomen, thigh, knee, etc.).

[0052] In some embodiments of the present invention, the calculation method of the sensitivity distribution matrix algorithm further includes: In the formula for: ;in The matrix is ​​n The positive definite matrix is ​​defined as the sensitivity matrix; Indicates human tissue in The electrical conductivity at a point; Indicates human tissue in Point density; Let be the complex vector of the conjugate electric field generated by the i-th channel at position r under unit excitation. This represents the transpose of the complex vector of the conjugate electric field generated at position r. This represents the radio frequency shim parameters. The complex electric field vector... This is the weighted sum of the complex electric field vectors generated by multiple channel coils at position r; its calculation formula is: (r) ;in Let be the excitation coefficient of the i-th channel coil. (r) is the complex electric field vector generated by the i-th channel at position r under unit excitation.

[0053] The specific testing steps are as follows:

[0054] Step 1: Begin measurement.

[0055] Step 2: Position the head of the human water phantom at the center of the transmitting coil. Specifically, position the head of the patient's water phantom at the geometric center of the transmitting coil of the magnetic resonance imaging device 1 to ensure the spatial position for subsequent electric field measurements.

[0056] Step 3: The signal source drives the RF coil port 1. Specifically, the control unit 104 controls the RF power source 101 to emit a preset power signal CH1, which drives the RF coil port 1 of the magnetic resonance device 1.

[0057] Step 4: Measure the electric field at the spatial location of the model using an electric field probe. Specifically, the electric field probe is used simultaneously to measure the electric field at the spatial location of the model. A robotic arm positions the probe point by point to thousands of preset measurement points inside the water model, collecting the electric field amplitude and phase information at each measurement point, which is recorded as the electric field value E1 corresponding to that port.

[0058] Step 5: Drive other coil ports. Specifically, control the RF power source 101 to emit power signals CH2, CH3...CHn (n≥2) in sequence to drive ports 2 to n of the RF coil of the magnetic resonance device 1. Repeat the probe positioning and electric field measurement process in the above steps for each port to obtain the electric field values ​​E2, E3...En corresponding to ports 2 to n in sequence. Finally, obtain the full-range electric field measurement dataset {E1, E2, ..., En} of n coil ports.

[0059] Step 6: Obtain the electric field E and calculate the SAR value. Specifically, based on the full-range electric field values ​​{E1, E2, ..., En} obtained in the above steps, calculate the actual specific absorption rate of different body parts of the patient using the sensitivity distribution matrix calculation formula.

[0060] In some embodiments of the present invention, such as Figure 1As shown, the magnetic resonance imaging device 1 further includes: a magnet 105, a gradient coil 106, a radio frequency transmitting coil 107, and a receiving coil 108; wherein, the magnet 105 is used to generate a main magnetic field, the gradient coil 106 is used to generate a gradient magnetic field to spatially encode the imaging area, the radio frequency transmitting coil 107 is used to transmit radio frequency pulses to the human body under the drive of the radio frequency power source 101, and the receiving coil 108 is used to collect the electric field response signals generated by the radio frequency pulse excitation of different parts of the human body. The magnetic resonance imaging (MRI) device 1 includes a magnet 105, a gradient coil 106, an RF transmitting coil 107, and a receiving coil 108. An RF power source 101 drives the gradient coil 106 (adjusting the gradient field strength and time via a current controller); a transmitting unit 102 drives the RF transmitting coil 107 (generating a specific waveform via an RF amplifier); a receiving unit 103 connects to the receiving coil 108 (processing signals via a preamplifier and an analog-to-digital converter); and a control unit 104 drives the power supply to the magnet 105 (maintaining a stable main magnetic field), the timing of the gradient coil 106, the waveform of the transmitting coil, and the sampling of the receiving coil 108. This clear mapping relationship makes system troubleshooting and maintenance more efficient (e.g., when the specific absorption rate is abnormal, it can quickly locate whether the current in the gradient coil 106 is unstable or the power of the transmitting coil is abnormal). Furthermore, when replacing the magnet 105 with a higher field strength or the receiving coil 108 array with a higher density, only the drive of the corresponding module needs to be adjusted, without reconstructing the entire system, which helps improve the adaptability and flexibility of the entire system, facilitating installation and subsequent maintenance.

[0061] In some embodiments of the present invention, such as Figure 1 As shown, the gradient coil 106 is a hollow cylinder placed inside the magnet 105. The gradient coil 106 receives power from the radio frequency power source 101 to generate a gradient magnetic field. Since the strength of the gradient magnetic field is directly related to the number of turns, current density, and geometry of the coil, setting the gradient coil 106 as a hollow cylinder structure can optimize the current path. The winding method of the cylindrical coil (such as uniformly distributing the winding along the circumference) can make the current form a more uniform magnetic field gradient in space. For example, when the Z-axis gradient coil 106 (along the long axis of the magnet 105) is wound symmetrically in a cylinder, the linearity of the magnetic field gradient generated by the current in the examination area (the patient's location) is better, avoiding the focus position shift of the radio frequency pulse caused by gradient nonlinearity. In addition, the hollow structure shortens the average radius of the coil (reduces the current loop length). Under the condition that the radio frequency power source 101 outputs the same current, the resistance loss of the coil is reduced, which helps to improve power utilization, reduce the heat load of the power source, and extend the service life of the equipment.

[0062] In some embodiments of the present invention, such as Figure 1As shown, the main magnetic field strength generated by the magnet 105 is 3.0T~7.0T. The main magnetic field strength directly affects the frequency of the radio frequency pulse. Within the strength range of 3.0T~7.0T, as the radio frequency increases, the dielectric constant and conductivity of the tissue change more significantly with frequency. The electric field response signal collected by the receiving unit 103 can more clearly reflect the energy absorption characteristics of different body parts of the patient. Based on this, the specific absorption rate value calculated by the computer device 2 is more accurate, avoiding the problem of missed detection or measurement errors caused by signal ambiguity under low field strength, thus improving the accuracy of the measurement results. In addition, under high field strength, the gradient field switching rate of the radio frequency power source 101 is faster (the gradient field strength is positively correlated with the main magnetic field strength), thereby achieving a smaller spatial resolution. The main magnetic field of 3.0T~7.0T can accurately locate different body parts of the patient. Combined with the local electric field response signal collected by the receiving unit 103, the computer device 2 can calculate the specific absorption rate of the human body by part (rather than the overall average) through the sensitivity distribution matrix algorithm, ensuring that the detection results are more realistic.

[0063] In some embodiments of the present invention, such as Figure 1 and Figure 2 As shown, the magnetic resonance imaging (MRI) device 1 also includes an electric field probe, which is used to measure the electric field vectors of different body parts of the patient in three-dimensional space. When the radio frequency electromagnetic field propagates in the body, the distribution of the electric field vector has significant spatial anisotropy: the electric field of different body parts may have amplitude and phase differences in the x, y, and z directions (e.g., the electric field direction is concentrated in the near field region, and tends to approximate a plane wave in the far field region). Traditional single-direction or scalar electric field measurement (measuring only |E|) will lose directional information, causing the spatial coupling effect of the electric field vector to be ignored when calculating the specific absorption rate. However, by directly measuring the three-dimensional electric field vector through the electric field probe, the spatial distribution characteristics of the electric field of each part can be completely captured (e.g., the direction of electric field lines, the direction of maximum field strength), and combined with the dielectric anisotropy of different body parts, the specific absorption rate calculation results are more consistent with reality. In addition, MRI scans often involve multiple parts of the whole body (e.g., head and neck, chest and abdomen, limbs), and the geometry and electromagnetic properties of different parts are significantly different, and their electric field distribution patterns are different. Traditional electric field measurements at fixed locations or in single areas cannot meet the detection requirements. The electric field probe of this magnetic resonance imaging device 1 can be flexibly moved to any part of the patient's body (such as the arm, abdomen, or back) through three-dimensional spatial positioning (e.g., driven by a robotic arm) and the three-dimensional electric field vector can be measured at each location. It can dynamically adjust the measurement position of the probe according to different clinical needs, and evaluate the actual specific absorption rate of the current scanning site in real time, avoiding detection failure caused by site switching.

[0064] like Figure 3 The diagram illustrates a flow chart of a magnetic resonance radio frequency security detection method applied to the magnetic resonance radio frequency security detection method according to an embodiment of this application. The steps are as follows:

[0065] Step S31: Send a radio frequency control signal to the control unit. The control unit receives instructions from the computer device and sends control instructions to the transmitting unit to transmit radio frequency pulse signals to the patient at the designated location. The control unit also sends control instructions to the receiving unit to enable the receiving unit to collect electric field response signals of different body parts of the patient after the radio frequency pulse signals are applied and feed them back to the control unit.

[0066] Step S32: The computer device 2 is electrically connected to the control unit 104; the computer device 2 receives electric field response signals from different body parts of the patient from the control unit 104, and obtains the corresponding human body electric field value from the electric field response signals; using a preset sensitivity distribution matrix algorithm, the specific absorption rate of different body parts of the patient is calculated based on the human body electric field value.

[0067] In some embodiments of the present invention, such as Figure 1 and Figure 4 As shown, the computer device 2 of the magnetic resonance radio frequency security detection system, and the flow of the method are as follows: Figure 4 As shown, it includes the following steps:

[0068] Step S41: The computer device 2 sends a radio frequency control signal to the control unit 104.

[0069] Step S42: The control unit 104 receives instructions from the computer device 2 and sends control instructions to the transmitting unit 102, causing the transmitting unit 102 to transmit radio frequency pulse signals to the patient at the designated location.

[0070] Step S43: The control unit 104 further sends a control command to the receiving unit 103 to enable the receiving unit 103 to collect the electric field response signals of different body parts of the patient after the radio frequency pulse signal is applied and feed them back to the control unit 104.

[0071] Step S44: The computer device 2 receives electric field response signals from different body parts of the patient from the control unit 104, and obtains the corresponding human electric field value from the electric field response signals.

[0072] Step S45: Using a preset sensitivity distribution matrix algorithm, the specific absorption rate of different body parts of the patient is calculated based on the human body electric field value.

[0073] Computer device 2 can monitor the specific absorption rate calculation results in real time through closed-loop control and adjust the radio frequency control signal in reverse (for example, when the specific absorption rate of a certain part is detected to be close to the threshold, the control unit 104 is immediately instructed to reduce the transmission power or shorten the pulse time, forming a dynamic optimization mechanism of "monitoring-feedback-adjustment", which helps to improve the safety and efficiency of magnetic resonance radio frequency detection.

[0074] In some embodiments of the present invention, such as Figure 1 and Figure 3 As shown, a computer device includes a memory, a processor, and a computer program stored in the memory. The processor executes the computer program to implement the magnetic resonance radio frequency safety detection method. The modular design of the computer device (processor + memory + program) works in conjunction with other components of the magnetic resonance device 1 (such as the transmitting unit 102 and the receiving unit 103): if the processor or memory is damaged, only the entire computer device needs to be replaced, without disassembling other modules of the magnetic resonance device 1, which can reduce maintenance time and costs.

[0075] Figure 5 This is a schematic block diagram of a computer device provided in an embodiment of this application. Figure 5 As shown, the computer device includes at least one processor 501, a memory 502, at least one network interface 503, and a user interface 505. The various components in the device are coupled together via a bus system 504. It is understood that the bus system 504 is used to implement communication between these components. In addition to a data bus, the bus system 504 also includes a power bus, a control bus, and a status signal bus. However, for clarity, in… Figure 5 In this document, all buses are referred to as bus systems. The user interface 505 may include a display, keyboard, mouse, trackball, clicker, buttons, a touchpad, or a touchscreen. It is understood that the memory 502 may be volatile memory or non-volatile memory, or both. The non-volatile memory may be read-only memory (ROM) or programmable read-only memory (PROM), which serves as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM) and synchronous static random access memory (SSRAM). The memories described in this embodiment are intended to include, but are not limited to, these and any other suitable categories of memory.

[0076] In this embodiment of the invention, the memory 502 is used to store various types of data to support the operation of the electronic terminal 500. Examples of this data include: any executable program for operation on the electronic terminal 500, such as the operating system 5021 and application programs 5022; the operating system 5021 contains various system programs, such as the framework layer, core library layer, driver layer, etc., for implementing various basic services and handling hardware-based tasks. The application program 5022 may contain various applications, such as a media player, browser, etc., for implementing various application services. The implementation of the XX method provided in this embodiment of the invention may be included in the application program 5022.

[0077] The methods disclosed in the above embodiments of the present invention can be applied to processor 501, or implemented by processor 501. Processor 501 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the integrated logic circuit of the hardware in processor 501 or by instructions in the form of software. The processor 501 may be a general-purpose processor, a digital signal processor (DSP), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Processor 501 can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. General-purpose processor 501 may be a microprocessor or any conventional processor, etc. The steps of the accessory optimization method provided in the embodiments of the present invention can be directly reflected as being executed by a hardware decoding processor, or being executed by a combination of hardware and software modules in the decoding processor. The software module may be located in a storage medium, which is located in memory. The processor reads the information in the memory and combines it with its hardware to complete the steps of the aforementioned method.

[0078] In an exemplary embodiment, the electronic terminal 500 may be used by one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), or complex programmable logic devices (CPLDs) to execute the aforementioned method.

[0079] As described above, the magnetic resonance radiofrequency safety detection method and magnetic resonance system of the present invention have the following beneficial effects: When in use, the magnetic resonance radiofrequency safety detection method and magnetic resonance system of the present invention control the transmitting unit to transmit radiofrequency pulses to a designated location through the control unit, and simultaneously control the receiving unit to collect electric field response signals (directly reflecting the electromagnetic field distribution in the tissue) of different body parts of the patient. Then, the computer equipment calculates the specific absorption rate based on the electric field value, realizing real-time, dynamic, and site-specific monitoring of radiofrequency energy absorption. It can provide timely warnings when the specific absorption rate approaches or exceeds the safety threshold, significantly improving the safety of MRI examinations.

[0080] The computer equipment uses a "pre-defined sensitivity distribution matrix algorithm" to calculate the specific absorptivity. Compared to traditional detection methods (such as point estimation based on the assumption of a homogeneous medium or simplified geometric models), this method results in some deviations in the calculation results. The sensitivity distribution matrix algorithm, based on this three-dimensional grid, performs volume integration, calculating the absorbed radio frequency power for each voxel and then summing them to obtain the total specific absorptivity of the target area. This "infinite element integration" method avoids the measurement error problems caused by blurred tissue boundaries or simplified models, significantly improving the accuracy and realism of the specific absorptivity calculation.

[0081] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0082] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A magnetic resonance radio frequency security detection system, characterized in that, include: A magnetic resonance imaging (MRI) device, comprising: a radio frequency power source, a transmitting unit, a receiving unit, and a control unit; the control unit is connected to the radio frequency power source, the transmitting unit, and the receiving unit respectively. The control unit sends control commands to the transmitting unit to cause the transmitting unit to transmit radio frequency pulse signals to the patient at a designated location; the control unit also sends control commands to the receiving unit to cause the receiving unit to collect electric field response signals of different body parts of the patient after the radio frequency pulse signals are applied and feed them back to the control unit. A computer device electrically connected to the control unit; the computer device receives electric field response signals from different body parts of the patient from the control unit, and obtains the corresponding human body electric field value from the electric field response signals; using a preset sensitivity distribution matrix algorithm, and based on the human body electric field value, the specific absorption rate of different body parts of the patient is calculated.

2. The magnetic resonance radio frequency security detection system according to claim 1, characterized in that: The sensitivity distribution matrix algorithm is used to characterize the specific absorption rate of different body parts of the patient, obtained by integrating within the volume enclosed by a three-dimensional mesh model of different body parts of the patient.

3. The magnetic resonance radio frequency security detection system according to claim 2, characterized in that: The sensitivity distribution matrix algorithm is calculated as follows: ； in, Indicates human tissue in Specific absorption rate at a point; Indicates human tissue in The electrical conductivity at a point; Indicates human tissue in Point density; Indicates all coil channels in The electric field complex vector of a point, V represents the volume enclosed by the three-dimensional mesh model of different body parts of the patient.

4. The magnetic resonance radio frequency security detection system according to claim 3, characterized in that: The calculation method of the sensitivity distribution matrix algorithm also includes: Among them, in the formula for: ;in The matrix is ​​n The positive definite matrix is ​​defined as the sensitivity matrix; Indicates human tissue in The electrical conductivity at a point; Indicates human tissue in Point density; Let be the complex vector of the conjugate electric field generated by the i-th channel at position r under unit excitation. This represents the transpose of the complex vector of the conjugate electric field generated at position r. This represents the radio frequency shimming parameters.

5. The magnetic resonance radio frequency security detection system according to claim 1, characterized in that: The magnetic resonance imaging device further includes: a magnet, a gradient coil, a radio frequency transmitting coil, and a receiving coil; wherein, the magnet is used to generate a main magnetic field, the gradient coil is used to generate a gradient magnetic field to spatially encode the imaging area, the radio frequency transmitting coil is used to transmit radio frequency pulses to the human body under the drive of the radio frequency power source, and the receiving coil is used to collect electric field response signals generated by radio frequency pulse excitation in different parts of the human body.

6. The magnetic resonance radio frequency security detection system according to claim 5, characterized in that: The gradient coil is a hollow cylinder placed inside the magnet, and the gradient coil receives power from the radio frequency power source to generate a gradient magnetic field.

7. A magnetic resonance radio frequency security detection system according to claim 5, characterized in that: The main magnetic field strength generated by the magnet is 3.0T~7.0T.

8. The magnetic resonance radio frequency security detection system according to claim 1, characterized in that: The magnetic resonance imaging device also includes an electric field probe, which is used to measure the electric field at the head spatial position of the patient's water phantom.

9. A magnetic resonance radio frequency security detection method, characterized in that: The computer equipment applied to the magnetic resonance radio frequency security detection system of claim 1; the method includes: The control unit sends a radio frequency control signal to the control unit, which receives instructions from the computer device and sends control instructions to the transmitting unit to transmit radio frequency pulse signals to the patient at a designated location. The control unit also sends control instructions to the receiving unit to enable the receiving unit to collect electric field response signals of different body parts of the patient after the radio frequency pulse signals are applied and feed them back to the control unit. The control unit receives electric field response signals from different body parts of the patient and obtains the corresponding human body electric field value from the electric field response signals; it uses a preset sensitivity distribution matrix algorithm and calculates the specific absorption rate of different body parts of the patient based on the human body electric field value.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the magnetic resonance radio frequency security detection method of claim 9.

Images