Security check stand column ferromagnetic detection system for nuclear magnetic resonance room

Abstract

The invention discloses a security check stand column ferromagnetic detection system for a nuclear magnetic resonance room, which comprises a ferromagnetic detection device, a door opening detection device and an alarm device, and is characterized in that the ferromagnetic detection device and the door opening detection device are arranged close to a door of the nuclear magnetic resonance room; the door opening detection device is electrically connected with the ferromagnetic detection device; the ferromagnetic detection device comprises a magnetic field induction assembly and a signal processing assembly, the output end of the magnetic field induction assembly is electrically connected with the input end of the signal processing assembly, and the magnetic field induction assembly sends a magnetic field change signal to the signal processing assembly; the signal processing assembly comprises a band-pass filtering and amplifying unit, and the band-pass filtering and amplifying unit is used for performing amplification, high-frequency filtering and low-frequency filtering coupling processing on the magnetic field change signal to obtain a processing signal; and the alarm device is electrically connected with the signal processing assembly and is used for acquiring and identifying the processing signal and carrying out alarm work according to an identification result, so that the probability of metal leak detection or false detection is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of ferromagnetic detection technology, and in particular to a ferromagnetic detection system for a security inspection column used in a nuclear magnetic resonance imaging (MRI) chamber. Background Technology

[0002] Magnetic resonance imaging (MRI) is a commonly used clinical imaging technique. It utilizes a strong magnetic field to create magnetic resonance between the hydrogen nuclei in the body and specific radio waves, ultimately producing an image through specialized equipment. MRI offers high resolution and clear images of soft tissues, helping doctors understand the presence, extent, and severity of lesions in the examined area, thus providing a basis for subsequent diagnosis and treatment.

[0003] Because MRI equipment is currently expensive, and given its strong magnetic environment, which is equivalent to 20,000 times the Earth's magnetic field, patients who have implanted or carry magnetic metal materials into the MRI room for examination may be at risk due to the equipment's powerful magnetic field.

[0004] Currently, most hospital MRI rooms lack adequate security screening equipment, relying solely on manual notification and examination, which is time-consuming, labor-intensive, and carries the risk of missed detections. Summary of the Invention

[0005] This invention provides a ferromagnetic detection system for security screening columns in MRI rooms, which addresses the problem of missed detection of magnetic metal substances implanted or carried by patients.

[0006] This invention provides a ferromagnetic detection system for a security check post in an MRI room, comprising: a ferromagnetic detection device, a door opening detection device, and an alarm device. The ferromagnetic detection device and the door opening detection device are both positioned close to the door of the MRI room. The door opening detection device is electrically connected to the ferromagnetic detection device to enable the ferromagnetic detection device to enter a working state when the door of the MRI room is opened.

[0007] The ferromagnetic detection device includes a magnetic field sensing component and a signal processing component. The output terminal of the magnetic field sensing component is electrically connected to the input terminal of the signal processing component, which is used to generate a magnetic field change signal when metal enters the detection range of the magnetic field sensing component. The magnetic field sensing component sends the magnetic field change signal to the signal processing component.

[0008] The signal processing component includes a bandpass filter amplification unit, which is used to amplify, perform high-frequency filtering, and low-frequency filtering coupled processing on the magnetic field change signal to obtain a processed signal;

[0009] The alarm device is electrically connected to the signal processing component. The alarm device is used to acquire and identify the processed signal and to perform alarm functions based on the identification results.

[0010] Furthermore, the bandpass filter amplification unit includes a voltage conditioning amplification module and one or more bandpass filter amplification modules connected in sequence. The input terminal of the first bandpass filter amplification module is connected to the output terminal of the magnetic field sensing component, and the output terminal of the last bandpass filter amplification module is connected to the input terminal of the voltage conditioning amplification module.

[0011] The bandpass filter amplifier module is used to amplify, high-frequency filter and low-frequency filter coupled processing of the magnetic field change signal to obtain a processed signal. The voltage conditioning amplifier module is used to connect to the alarm device and to adjust the voltage of the processed signal to the working voltage of the alarm device.

[0012] Furthermore, the bandpass filter amplifier module includes a filter amplifier, an RC high-pass filter, and an RC low-pass filter;

[0013] The input terminal of the RC high-pass filter is connected to the output terminal of the filter amplifier, and the second terminal is connected to the inverting input terminal of the filter amplifier to achieve high-frequency filtering.

[0014] The first terminal of the RC low-pass filter is connected to the inverting input terminal of the amplifier, and the second terminal of the RC low-pass filter is connected to ground, which is used to achieve low-frequency filtering.

[0015] Furthermore, the signal processing component also includes a first capacitor and a first resistor. The first end of the first resistor is connected to the magnetic field sensing component, the first end of the first capacitor is connected to ground, and the second end of the first resistor and the second end of the second capacitor are connected together to the non-inverting output terminal of the first filter amplifier.

[0016] Furthermore, the output terminal of the filter amplifier of the preceding bandpass filter amplifier module is connected to the non-inverting input terminal of the filter amplifier of the following bandpass filter amplifier module.

[0017] Furthermore, the voltage conditioning amplifier module includes a voltage regulating amplifier and a bias voltage circuit. The output terminal of the filter amplifier in the last bandpass filter amplifier module is connected to the inverting input terminal of the voltage regulating amplifier, and the output terminal of the bias voltage circuit is connected to the non-inverting input terminal of the voltage regulating amplifier.

[0018] Furthermore, the bias voltage circuit includes a power supply, a ninth resistor, a tenth resistor, and an eighth capacitor. The first terminals of the ninth resistor, the tenth resistor, and the eighth capacitor are connected together to the non-inverting input terminal of the voltage regulator amplifier. The second terminal of the tenth resistor is connected to the power supply. The second terminals of the ninth resistor and the eighth capacitor are connected together to ground.

[0019] Furthermore, the output terminal of the filter amplifier in the last bandpass filter amplifier module is connected to the inverting input terminal of the voltage regulator amplifier in sequence through the seventh capacitor and the eighth resistor, and the output terminal of the voltage regulator amplifier is connected to the input terminal of the filter amplifier in sequence through the sixth capacitor and the sixth resistor.

[0020] Furthermore, the voltage conditioning and amplification module also includes an eleventh resistor and a ninth capacitor. The output terminal of the filter amplifier is connected to the first terminal of the eleventh resistor, the first terminal of the ninth capacitor is connected to ground, and the second terminals of the ninth capacitor and the eleventh resistor are connected together to the alarm device.

[0021] Furthermore, it includes a first column, a second column, and a proximity detection device, wherein the first column and the second column are used to be installed on both sides of the entrance to the MRI room;

[0022] Both the first column and the second column are equipped with the ferromagnetic detection device and the proximity detection device. The proximity detection device is electrically connected to the ferromagnetic detection device to enable the ferromagnetic detection device to enter the working state when the patient approaches the door of the MRI room.

[0023] The proximity detection device includes millimeter-wave radar.

[0024] As can be seen from the above technical solutions, the present invention has the following advantages:

[0025] On the one hand, the ferromagnetic detection device will only enter the working state when the door of the MRI room is detected to be open by the door opening detection device, which can avoid unnecessary continuous operation of the ferromagnetic detection device, thus saving energy and extending its service life.

[0026] On the other hand, this embodiment uses a magnetic field sensing component to detect whether a magnetic field change signal is generated, and determines whether the patient is carrying metal through the detection area of ​​the ferromagnetic detection device.

[0027] On the other hand, when the door of the MRI room is opened, the movement of equipment inside generates low-frequency noise interference. This interference is captured by the magnetic field sensing component, thus interfering with the detection of changes in the metal magnetic field signal. Simultaneously, the complex environment also contains high-frequency electromagnetic interference, radio frequency interference, and high-frequency noise generated by transient currents in the switching power supply. All of these high-frequency and low-frequency noises mix with the magnetic field change signal triggered by a person carrying metal while walking normally, affecting the accurate identification of useful magnetic field change signals caused by metal. Therefore, this embodiment adds a signal processing component including a bandpass filter amplification unit. The bandpass filter amplification unit amplifies the magnetic field change signal and performs high-frequency and low-frequency filtering coupled processing, i.e., variable amplification-side filtering processing. The final processed signal effectively reduces interference from high-frequency and low-frequency noise, accurately retains the magnetic field change signal caused by a person carrying metal while walking normally, and reduces the probability of missed or false detections of metal.

[0028] On the other hand, when the signal processing component outputs a clean and accurate signal indicating a change in the magnetic field caused by a person carrying metal walking normally, the alarm device acquires and identifies the signal and promptly issues an alarm based on the identification result, automatically reminding the patient carrying the metal. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A schematic diagram (I) of a ferromagnetic detection system for a security inspection column in a nuclear magnetic resonance chamber, provided as an embodiment of the present invention.

[0031] Figure 2 A schematic diagram (II) of a ferromagnetic detection system for a security inspection column in a nuclear magnetic resonance chamber, provided as an embodiment of the present invention.

[0032] Figure 3 A schematic diagram (III) of a ferromagnetic detection system for a security inspection column in a nuclear magnetic resonance chamber, provided as an embodiment of the present invention.

[0033] Figure 4 A circuit diagram of the signal processing component in a ferromagnetic detection system for a security inspection column in a nuclear magnetic resonance chamber, provided for an embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of a ferromagnetic detection system for a security inspection column in a nuclear magnetic resonance imaging (MRI) room, provided by an embodiment of the present invention.

[0035] Figure 6 A schematic diagram of the port connections of the MCU main control board located on the first column in a ferromagnetic detection system for a security inspection column in an MRI room, provided as an embodiment of the present invention:

[0036] Figure 7 A schematic diagram of the radar detection range in a ferromagnetic detection system for a security inspection column in a nuclear magnetic resonance chamber, provided as an embodiment of the present invention;

[0037] Figure 8 This is a schematic diagram of the structure of a column in a ferromagnetic detection system for a security inspection column in a nuclear magnetic resonance chamber, provided by an embodiment of the present invention.

[0038] Explanation of reference numerals in the attached drawings: 1. First column; 2. Second column; 3. Left radar; 4. Right radar; 5. Power button; 6. MRI room door; 7. Door opening detection device; 8. Base; 9. Touch screen display device; 10. Power supply device; 11. First power communication line; 12. Second power communication line. Detailed Implementation

[0039] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0040] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the present application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0041] Please see Figure 1A ferromagnetic detection system for a security inspection column in an MRI room includes: a ferromagnetic detection device, a door opening detection device, and an alarm device. Both the ferromagnetic detection device and the door opening detection device are installed near the door of the MRI room. The door opening detection device is electrically connected to the ferromagnetic detection device to enable the ferromagnetic detection device to enter the working state when the door of the MRI room is opened.

[0042] The ferromagnetic detection device includes a magnetic field sensing component and a signal processing component. The output end of the magnetic field sensing component is electrically connected to the input end of the signal processing component. This is used to generate a magnetic field change signal when metal enters the detection range of the magnetic field sensing component. The magnetic field sensing component then sends the magnetic field change signal to the signal processing component.

[0043] The signal processing component includes a bandpass filter amplification unit, which is used to amplify, filter at high frequencies, and couple low frequencies the magnetic field change signal to obtain the processed signal.

[0044] The alarm device is electrically connected to the signal processing component. The alarm device is used to acquire and identify the processed signal and to trigger an alarm based on the identification result.

[0045] Understandably, in practice, on the one hand, the ferromagnetic detection device will only enter the working state when the door of the MRI room is detected to be open by the door opening detection device, which can avoid unnecessary continuous operation of the ferromagnetic detection device, thus saving energy and extending its service life.

[0046] On the other hand, this embodiment uses a magnetic field sensing component to detect whether a magnetic field change signal is generated, and determines whether the patient is carrying metal through the detection area of ​​the ferromagnetic detection device.

[0047] On the other hand, when the door of the MRI room is opened, the movement of equipment inside generates low-frequency noise interference. This interference is captured by the magnetic field sensing component, thus interfering with the detection of changes in the metal magnetic field signal. Simultaneously, the complex environment also contains high-frequency electromagnetic interference, radio frequency interference, and high-frequency noise generated by transient currents in the switching power supply. All of these high-frequency and low-frequency noises mix with the magnetic field change signal triggered by a person carrying metal while walking normally, affecting the accurate identification of useful magnetic field change signals caused by metal. Therefore, this embodiment adds a signal processing component including a bandpass filter amplification unit. The bandpass filter amplification unit amplifies the magnetic field change signal and performs high-frequency and low-frequency filtering coupled processing, i.e., variable amplification-side filtering processing. The final processed signal effectively reduces interference from high-frequency and low-frequency noise, accurately retains the magnetic field change signal caused by a person carrying metal while walking normally, and reduces the probability of missed or false detections of metal.

[0048] On the other hand, when the signal processing component outputs a clean and accurate signal indicating a change in the magnetic field caused by a person carrying metal walking normally, the alarm device acquires and identifies the signal and promptly issues an alarm based on the identification result, automatically reminding the patient carrying the metal.

[0049] Please see Figure 2 In a more specific embodiment, the bandpass filter amplification unit includes a voltage conditioning amplification module and one or more bandpass filter amplification modules connected in sequence. The input terminal of the first bandpass filter amplification module is connected to the output terminal of the magnetic field sensing component, and the output terminal of the last bandpass filter amplification module is connected to the input terminal of the voltage conditioning amplification module.

[0050] The bandpass filter amplifier module is used to amplify, filter at high frequencies and couple low frequencies to obtain the processed signal from the magnetic field change signal. The voltage conditioning amplifier module is used to connect to the alarm device and adjust the voltage of the processed signal to the working voltage of the alarm device.

[0051] Understandably, in practice, after obtaining a more accurate processed signal through multiple bandpass filter amplification modules, a voltage conditioning amplification module is set after the bandpass filter amplification module to adjust the voltage of the processed signal to the operating voltage of the alarm device. This ensures that the voltage of the processed signal and the operating voltage of the alarm device are precisely matched, guaranteeing a stable and reliable response from the alarm device.

[0052] In a more specific embodiment, the alarm device includes a signal analysis component and an alarm component.

[0053] Please see Figure 3 In a more specific embodiment, the bandpass filter amplifier module includes a filter amplifier, an RC high-pass filter, and an RC low-pass filter;

[0054] The input terminal of the RC high-pass filter is connected to the output terminal of the filter amplifier, and the second terminal is connected to the inverting input terminal of the filter amplifier to achieve high-frequency filtering.

[0055] The first terminal of the RC low-pass filter is connected to the inverting input of the filter amplifier, and the second terminal of the RC low-pass filter is connected to ground to achieve low-frequency filtering.

[0056] Please see Figure 4 In a more specific embodiment, the RC high-pass filter includes a third resistor and a third capacitor, which are connected in parallel with the negative feedback terminal of the filter amplifier. The RC low-pass filter includes a second resistor and a second capacitor, with the first end of the second resistor connected to the inverting input terminal of the filter amplifier, the second end of the second resistor connected to the first end of the second capacitor, and the second end of the second capacitor connected to ground.

[0057] Understandably, in practical implementation, precise filtering of magnetic field change signals can be achieved through the synergistic effect of RC high-pass and RC low-pass filters: the RC high-pass filter is responsible for filtering out high-frequency interference, while the RC low-pass filter focuses on suppressing low-frequency noise. The combination of the two not only offers significant technical advantages but also balances practicality and stability. From a cost and structural perspective, this solution offers high cost-effectiveness and simplicity, requiring fewer components and significantly reducing PCB footprint, resulting in a more compact circuit layout. Regarding parameter adjustment flexibility, careful selection of component configuration allows for independent adjustment of key parameters, such as center frequency, quality factor, and bandwidth-center frequency gain, all achievable by adjusting relevant RC parameters. In terms of performance, it possesses the ability to achieve high quality factor values ​​while exhibiting low output impedance and providing gain, further ensuring signal processing effectiveness. Furthermore, it exhibits outstanding resistance to load interference—thanks to the low output impedance of the filter amplifier, changes in the input impedance of subsequent circuits will not affect the filter's transfer function, ensuring consistently stable filter performance unaffected by load fluctuations.

[0058] In a more specific embodiment, the signal processing component further includes a first capacitor and a first resistor, a first end of the first resistor being connected to the magnetic field sensing component, a first end of the first capacitor being connected to ground, and a second end of the first resistor and a second end of the second capacitor being connected together to the non-inverting output of the first filter amplifier.

[0059] Understandably, in practical implementation, the design of the first filter amplifier in a metal detection system requires specific component configurations to address different signal issues, ensuring detection accuracy and equipment safety. Considering the first resistor connected in series at the input of the first filter amplifier, due to differences in metal size, larger metals passing through the detection coil cause a drastic change in magnetic flux. Based on the principle of electromagnetic induction, the coil will induce a strong induced electromotive force signal whose amplitude can surge from the normal mV level to the V level. This signal far exceeds the input stage safety threshold of the filter amplifier. To prevent strong signals from breaking down the amplifier or causing saturation distortion, the first resistor in series plays a crucial role: firstly, by "current limiting" according to Ohm's law, it restricts the current flowing into the first filter amplifier, preventing large currents from damaging it; secondly, it forms a voltage divider circuit with the input impedance of the first filter amplifier, proportionally reducing the V-level strong signal to the mV level amplitude within the linear operating range of the first filter amplifier, ensuring stable operation of the detection system.

[0060] Looking at the design of the first capacitor connected in parallel at the output end, when a patient carries a small piece of metal, the metal entering the detection coil will change the coil inductance, thereby causing a weak low-frequency magnetic field change in the Hz-kHz range around the coil with a very small amplitude. This is a useful signal that needs to be captured. However, there are three types of strong high-frequency interference in the MRI (Magnetic Resonance Imaging) environment: the 10-300MHz radio frequency magnetic field of the MRI equipment itself, the kHz-MHz high-frequency pulse noise induced by the rapid switching of gradient magnetic fields, and the high-frequency electromagnetic radiation generated by other equipment in the hospital. If these are not filtered out in advance, and the "useful relatively low-frequency magnetic field induced by metal + strong high-frequency interference" is directly sent to the amplifier, the "indiscriminate" gain of the filter amplifier will cause the "interference to be amplified preferentially": assuming a gain of 1000 times, 1mV of high-frequency interference will be amplified to 1V, while 1μV of useful relatively low-frequency magnetic field induced by metal will only be amplified to 1mV. The high-frequency interference will completely "overwhelm" the useful signal, leading to misjudgment or missed detection by subsequent circuits. Therefore, the first capacitor connected in parallel can filter high-frequency signals before the filter amplifier amplifies them, "stripping away" strong interference, and allowing only the weak, useful, relatively low-frequency magnetic field induced by the metal to enter the filter amplifier. This allows the filter amplifier to amplify the useful, relatively low-frequency magnetic field induced by the metal, fundamentally ensuring the accuracy of the detection.

[0061] In a more specific embodiment, the output of the filter amplifier of the preceding bandpass filter amplifier module is connected to the non-inverting input of the filter amplifier of the following bandpass filter amplifier module.

[0062] Understandably, in practical implementation, a specific signal transmission path is used in the cascaded design of bandpass filter amplifier modules to optimize overall performance: the output of the filter amplifier in the preceding bandpass filter amplifier module is designed to be directly connected to the non-inverting input of the filter amplifier in the following bandpass filter amplifier module. The core advantage of this connection method is that it can fully utilize the circuit characteristics of the non-inverting amplifier—because the non-inverting input of the non-inverting amplifier itself has extremely high input impedance, when the output signal of the preceding filter amplifier is connected to the non-inverting input of the following filter amplifier, the following filter amplifier will not have a significant load effect on the output of the preceding filter amplifier. This avoids attenuation or distortion of the output signal of the preceding filter amplifier and ensures that the entire cascaded system always maintains high input impedance characteristics, laying a stable foundation for the accurate conditioning and amplification of subsequent signals. This is especially suitable for electronic systems with high requirements for the transmission accuracy of weak signals.

[0063] In a more specific embodiment, the signal processing component includes two bandpass filter amplification modules, namely a first bandpass filter amplification module and a second bandpass filter amplification module. The first bandpass filter amplification module includes a first amplifier (U1C TL084l), and the second bandpass filter amplification module includes a second amplifier (U1B TL084l). The output terminal of the first amplifier is connected to the non-inverting input terminal of the second amplifier.

[0064] Understandably, in practice, the amplification effect of multi-stage amplifiers significantly increases the total voltage gain of the signal, introduces a negative feedback mechanism to stabilize the operating point, effectively suppresses the impact of external factors such as temperature and power supply fluctuations on performance, and improves linearity and frequency characteristics. The first amplifier initially suppresses noise, and the second amplifier further processes the signal, resulting in an overall noise level lower than that of a single-stage amplifier circuit.

[0065] In a more specific embodiment, the first bandpass filter amplifier module includes a first amplifier (filter amplifier), a first RC high-pass filter, and a first RC low-pass filter. The input terminal of the first RC high-pass filter is connected to the output terminal of the first amplifier, and the second terminal is connected to the inverting input terminal of the first amplifier for high-frequency filtering. The first terminal of the first RC low-pass filter is connected to the inverting input terminal of the first amplifier, and the second terminal is connected to ground for low-frequency filtering. The first RC high-pass filter includes a third resistor and a third capacitor, which are connected in parallel with the negative feedback terminal of the first amplifier. The first RC low-pass filter includes a second resistor and a second capacitor. The first terminal of the second resistor is connected to the inverting input terminal of the first amplifier, and the second terminal of the second resistor is connected to the first terminal of the second capacitor. The second terminal of the second capacitor is connected to ground.

[0066] The second bandpass filter amplifier module includes a second amplifier (filter amplifier), a second RC high-pass filter, and a second RC low-pass filter. The input terminal of the second RC high-pass filter is connected to the output terminal of the second amplifier, and the second terminal is connected to the inverting input terminal of the second amplifier for high-frequency filtering. The first terminal of the second RC low-pass filter is connected to the inverting input terminal of the second amplifier, and the second terminal is connected to ground for low-frequency filtering. The second RC high-pass filter includes a fifth resistor and a fifth capacitor, which are connected in parallel with the negative feedback terminal of the second amplifier. The second RC low-pass filter includes a fourth resistor and a fourth capacitor. The first terminal of the fourth resistor is connected to the inverting input terminal of the first amplifier, the second terminal of the fourth resistor is connected to the first terminal of the fourth capacitor, and the second terminal of the fourth capacitor is connected to ground.

[0067] In a more specific embodiment, the output of the first amplifier is connected to the non-inverting input of the second amplifier via a seventh resistor.

[0068] Understandably, in practice, the seventh resistor can be called the input resistor or the compensation resistor. Its primary purpose is to reduce the input offset voltage and suppress DC error (compensating for the input bias current and reducing the output DC offset). Secondly, it is for the protection of the second amplifier input stage, including current limiting and ESD protection.

[0069] In a more specific embodiment, the voltage conditioning amplifier module includes a voltage regulating amplifier, which is... Figure 4 The third amplifier (U2B TL084l), the bias voltage circuit, and the output of the filter amplifier of the last bandpass filter amplifier module are connected to the inverting input of the voltage regulator amplifier, and the output of the bias voltage circuit is connected to the non-inverting input of the amplifier.

[0070] Understandably, in practical implementation, connecting the output of the filter amplifier in the last bandpass filter amplifier module to the inverting input of the filter amplifier creates an inverting amplifier structure with excellent common-mode interference immunity. This design effectively suppresses common-mode noise mixed in during signal transmission, ensuring the stability and accuracy of the output signal. On the other hand, connecting the output of the last filter amplifier to the inverting input of the voltage regulator amplifier, and connecting the output of the bias voltage circuit to the non-inverting input of the amplifier, this independent connection design cleverly separates the two key functions of "DC operating point setting" and "AC signal amplification"—the bias voltage circuit only calibrates the DC operating state and does not interfere with the transmission and amplification of the AC signal; while the amplification path formed by the inverting input focuses solely on AC signal processing and is unaffected by DC bias adjustment. Ultimately, this achieves the mutual non-interference of the two functions, ensuring both the stability of the DC operating point and the accuracy and purity of the AC signal amplification.

[0071] In a more specific embodiment, the bias voltage circuit includes a power supply, a ninth resistor, a tenth resistor, and an eighth capacitor. The first terminals of the ninth resistor, the tenth resistor, and the eighth capacitor are connected together to the non-inverting input terminal of the voltage regulator amplifier. The second terminal of the tenth resistor is connected to the power supply. The second terminals of the ninth resistor and the eighth capacitor are connected together to ground.

[0072] Understandably, in practical implementation, in a single-supply AC amplifier circuit, a suitable static DC operating point, i.e., a bias voltage operating point, is set for the filter amplifier so that the output AC signal can swing up and down around this voltage, i.e., the median value, thereby avoiding signal clipping and distortion. The eighth capacitor is used to filter out noise from the power supply signal and provide a stable power supply signal to the non-inverting input of the voltage regulator amplifier.

[0073] In a more specific embodiment, the output of the last filter amplifier is connected to the inverting input of the voltage regulator amplifier in sequence through the seventh capacitor and the eighth resistor, and the output of the voltage regulator amplifier is connected to the input of the third amplifier in sequence through the sixth capacitor and the sixth resistor.

[0074] Understandably, in practice, the inverting input of the voltage regulator amplifier is connected in series with a seventh capacitor and an eighth resistor, forming an active filter with a certain bandwidth frequency response together with the RC (sixth capacitor and sixth resistor) at the negative feedback terminal of the voltage regulator amplifier. The value of the eighth resistor directly affects the gain of the input signal.

[0075] In a more specific embodiment, the voltage conditioning amplifier module further includes an eleventh resistor and a ninth capacitor. The output terminal of the third amplifier is connected to the first terminal of the eleventh resistor, the first terminal of the ninth capacitor is connected to ground, and the second terminals of the ninth capacitor and the eleventh resistor are used together to connect to an alarm device.

[0076] It should be noted that the signal analysis components of the alarm device include an ADC (analog-to-digital converter chip).

[0077] Understandably, in practical implementation, the eleventh resistor serves several key functions: First, its most direct and crucial role is current limiting protection, restricting the maximum output current and protecting the pins of subsequent stages. Second, the eleventh and ninth resistors together form a first-order RC low-pass filter, filtering out high-frequency noise and glitches in the signal reaching the ADC input, resulting in a cleaner signal, improved signal-to-noise ratio, and higher measurement accuracy. Third, it improves dynamic performance and stability. The alarm device's signal analysis components include an ADC, which has an input capacitor at its input pin, and parasitic capacitance exists in the PCB traces. Directly driving a capacitive load at the output of the voltage regulator amplifier can easily cause ringing or oscillation in the output response, leading to longer settling time and decreased dynamic performance. Connecting the eleventh resistor in series between the output of the voltage regulator amplifier and the load isolates them, increasing circuit damping, effectively suppressing ringing and oscillation, allowing the signal to stabilize to its final value quickly, and improving settling time. Simultaneously, the ninth capacitor connected in parallel provides a local charge source, reducing the burden of the op-amp directly charging the ADC input capacitor.

[0078] In a more specific embodiment, the positive power supply terminals of the first amplifier and the second amplifier are connected to a +12V voltage, and the negative power supply terminals are connected to a -12V voltage.

[0079] Understandably, in practice, this power supply method can accurately amplify the weak alternating magnetic field signal caused by ferromagnetic materials, retain the complete information of the positive and negative half-cycles of the signal, and help improve detection sensitivity and accuracy.

[0080] In a more specific embodiment, the positive power supply terminal of the third amplifier is connected to a 12V voltage, and the negative power supply terminal is connected to ground.

[0081] Understandably, in practical implementation, the third-stage amplifier may require better matching with the ADC in the alarm device or subsequent loads or other circuit modules. 3.3V is a common low-voltage standard; many modern integrated circuits, microprocessors, and other devices typically operate at 3.3V or lower. Setting the voltage of the third-stage amplifier to 3.3V facilitates connection to these subsequent circuits, reducing the complexity and power consumption of level conversion. The power supply method in this embodiment is based on the voltage follower principle, ensuring that the signal voltage output by the third amplifier is infinitely close to the input voltage at the non-inverting input terminal of the third amplifier.

[0082] Please see Figure 5 In a more specific embodiment, it includes a first column 1, a second column 2 and a proximity detection device, wherein the first column 1 and the second column 2 are used to be installed on both sides of the doorway of the MRI room 6;

[0083] Both the first column 1 and the second column 2 are equipped with a ferromagnetic detection device and a proximity detection device. The proximity detection device is electrically connected to the ferromagnetic detection device to enable the ferromagnetic detection device to enter the working state when the patient approaches the MRI room door 6.

[0084] Proximity detection devices include millimeter-wave radar.

[0085] Understandably, in practical implementation, on the one hand, whether a person is carrying metal objects or approaching the door, they may enter from the left, right, or stop in the middle of the door. If only a single-sided support is installed, a "detection blind spot" will form on the opposite side of the door (the side furthest from the support). For example, if a person approaches the door from the side without the support, or passes through that side carrying metal objects, the device may miss the detection due to the distance being too far (outside the effective detection range of the sensor), leading to the failure of safety or control functions. Double-sided supports, through a "symmetrical layout," allow the detection ranges of the two devices to overlap in the middle of the door, forming a "complete horizontal detection band," ensuring that no matter which side a person / object approaches or passes through, it can be accurately detected by at least one device. On the other hand, the configured radar is a millimeter-wave radar, which is smaller in size than infrared diffuse reflection and lidar, and can penetrate non-metallic, non-transparent materials such as plastic, glass, acrylic, and wood, making it easier to integrate into the product and allowing for a more flexible and aesthetically pleasing design. Millimeter-wave radar can overcome the limitations of existing infrared diffuse reflection and lidar modules in terms of their application environment. It is not affected by smoke, strong light, or dark objects absorbing infrared light, resulting in more stable operation. Furthermore, by incorporating proximity detection devices, false alarms and unnecessary detection work can be reduced.

[0086] In a more specific embodiment, the magnetic field sensing component includes multiple detection coils. Multiple detection coils are evenly distributed on the first column 1 and the second column 2. A higher number of coils results in higher detection accuracy, but also higher cost. The design typically includes provisions for expansion circuitry to facilitate future expansion and increase in the number of detection coils.

[0087] In a more specific embodiment, multiple detection coils on the first column 1 and the second column 2 are distributed sequentially from top to bottom, adapted to the patient's height; a left radar 3 and a right radar 4 are installed on the first column 1 and the second column 2 (the detection range of the radar is as follows). Figure 7 As shown in the figure, the MRI door 6 can be sensed no matter which direction the patient approaches from.

[0088] In a more specific embodiment, the system further includes a power supply device 10 and a touch display device 9. The power supply device 10 is connected to the first column 1 via the touch display device 9 and via a first power communication line 11. The second column 2 is connected to the first column 1 via a second power communication line 12 to achieve power supply and communication functions. The door opening detection device 7 is connected to the first column 1.

[0089] Understandably, in practical implementation, on the one hand, the power supply device 10 only outputs one power line to power the door opening detection device 7, the first column 1, and the second column 2 via the touch screen display device 9. This results in a simple structure that is easy to maintain and saves costs. Simultaneously, it facilitates the control of the door opening detection device 7, the first column 1, and the second column 2 via the touch screen display device 9, enabling one-button power on / off.

[0090] In a more specific embodiment, a power button 5 is provided at the bottom of the first column 1, and the power supply device 10 is connected to the first column 1 via a touch screen device 9 and a first power communication line 11. The second column 2 is connected to the first column 1 via a second power communication line 12 to realize power supply and communication functions. The door opening detection device 7 is connected to the first column 1. Therefore, the system can be started or stopped with one click via the power button 5.

[0091] Please see Figure 6 In a more specific embodiment, the touch display device 9, the door opening detection device 7, and the second column 2 are all connected to the MCU main control board of the first column 1. The alarm device, detection coil, left radar 3, and right radar 4 on the first column 1 are respectively connected to the MCU main control board. The alarm components in the alarm device include a buzzer and an indicator light.

[0092] In a more specific embodiment, the door opening detection device 7 is a door opening sensing sensor.

[0093] In a more specific embodiment, the door opening sensor and left and right radar sensors equipped with the security inspection column ferromagnetic detection system can all have their effective detection range set in the unit menu bar of the touch screen display, adapting to the installation and commissioning of MRI rooms of various widths and heights.

[0094] In a more specific embodiment, the touch display unit's menu bar can be used to set various radar operating modes:

[0095] Left Radar 3 Mode: Alarm detection information will only be output when passing on the left and triggering Left Radar 3;

[0096] Right Radar 4 Mode: Alarm detection information will only be output when right radar 4 is triggered by passing on the right.

[0097] Left and right radar mode: When passing through both sides, triggering both radars will output alarm detection information;

[0098] In a more specific implementation, the columns can be used in pairs, mounted on the left and right walls, or individually placed in the middle of the entrance for left and right passage via the base 8, or easily moved using casters. Please refer to [link / reference]. Figure 8 .

[0099] In a more specific embodiment, the columns can be installed on both sides of the MRI door by means of hanging, or they can be erected in front of the MRI room door 6 by means of the base 8.

[0100] Understandably, in practice, by setting the base 8, the width of the security gate formed by the first column 1 and the second column 2 can be adjusted, which facilitates the passage of the hospital's non-magnetic transport vehicle.

[0101] In a more specific embodiment, the working principle of the ferromagnetic detection system for a security checkpoint column in an MRI room provided in this embodiment is as follows:

[0102] S01. The door opening sensor waits for a trigger. If it is not triggered, the system will not perform a detection or output a detection result. If it is triggered, proceed to step S02.

[0103] S02. The system detects whether there is anyone passing in the set radar direction. If not, the system does not perform detection and does not output detection results. If there is, proceed to step S03.

[0104] S03. The system detects whether the magnetic metal amplitude has reached the preset value. If not, the system does not perform the detection and does not output the detection result. If yes, proceed to step S04.

[0105] S04. Output the corresponding area's audible and visual alarm to prompt a second re-inspection.

[0106] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A security column ferromagnetic detection system for use in a nuclear magnetic resonance room, characterized by, The application relates to a nuclear magnetic resonance (NMR) room door magnetic detection device, which comprises a ferromagnetic detection device, a door opening detection device and an alarm device, wherein the ferromagnetic detection device and the door opening detection device are arranged close to a door of the NMR room; the door opening detection device is electrically connected with the ferromagnetic detection device to realize that the ferromagnetic detection device enters a working state when the door of the NMR room is opened; the ferromagnetic detection device comprises a magnetic field sensing component and a signal processing component; the output end of the magnetic field sensing component is electrically connected with the input end of the signal processing component to realize that a magnetic field change signal is generated when metal enters the detection range of the magnetic field sensing component, and the magnetic field sensing component sends the magnetic field change signal to the signal processing component; the signal processing component comprises a band-pass filter amplification unit which is used for amplifying, high-frequency filtering and low-frequency filtering coupling processing of the magnetic field change signal to obtain a processing signal; the alarm device is electrically connected with the signal processing component, and the alarm device is used for acquiring and identifying the processing signal and performing alarm work according to the identification result. The band-pass filter amplification unit comprises a voltage conditioning amplification module and one or more band-pass filter amplification modules which are connected in sequence; the input end of the first band-pass filter amplification module is connected with the output end of the magnetic field sensing component; the output end of the last band-pass filter amplification module is connected with the input end of the voltage conditioning amplification module; the band-pass filter amplification module is used for amplifying, high-frequency filtering and low-frequency filtering coupling processing of the magnetic field change signal to obtain a processing signal; the voltage conditioning amplification module is used for being connected with the alarm device and adjusting the voltage of the processing signal to the working voltage of the alarm device. The band-pass filter amplification module comprises a filter amplifier, an RC high-pass filter and an RC low-pass filter; the input end of the RC high-pass filter is connected with the output end of the filter amplifier; the second end is connected with the inverting input end of the filter amplifier to realize high-frequency filtering; the first end of the RC low-pass filter is connected with the inverting input end of the amplifier; the second end of the RC low-pass filter is connected with the ground to realize low-frequency filtering. The signal processing component further comprises a first capacitor and a first resistor; the first end of the first resistor is connected with the magnetic field sensing component; the first end of the first capacitor is connected with the ground; the second end of the first resistor and the second end of the second capacitor are commonly connected with the non-inverting output end of the first filter amplifier. The output end of the filter amplifier of the former band-pass filter amplification module is connected with the non-inverting input end of the filter amplifier of the latter band-pass filter amplification module.

2. The ferromagnetic detection system for security columns in an NMR room according to claim 1, characterized in that, The voltage conditioning amplification module comprises a voltage regulating amplifier and a bias voltage circuit; the output end of the filter amplifier of the last band-pass filter amplification module is connected with the inverting input end of the voltage regulating amplifier; the output end of the bias voltage circuit is connected with the non-inverting input end of the voltage regulating amplifier. ​ 3. The ferromagnetic detection system for a security column for a nuclear magnetic resonance room according to claim 2, characterized in that, ​ ​ ​ 4. The ferromagnetic detection system for security posts in an NMR chamber according to claim 3, characterized in that, ​ 5. The ferromagnetic detection system for a security column for a nuclear magnetic resonance room according to claim 3, characterized in that, ​ 6. The ferromagnetic detection system for security posts in an NMR chamber according to claim 3, characterized in that, ​ 7. The ferromagnetic detection system for a security column for a nuclear magnetic resonance room according to claim 6, characterized in that, The bias voltage circuit comprises a power supply, a ninth resistor, a tenth resistor and an eighth capacitor, first ends of the ninth resistor, the tenth resistor and the eighth capacitor are connected with a positive input end of the voltage regulating amplifier in common, a second end of the tenth resistor is connected with the power supply, a second end of the ninth resistor and a second end of the eighth capacitor are connected with the ground in common.

8. The ferromagnetic detection system for a security column for a nuclear magnetic resonance room according to claim 6, characterized in that, An output end of the filter amplifier of the last band-pass filter amplification module is connected with an inverting input end of the voltage regulating amplifier through a seventh capacitor and an eighth resistor in sequence, and output ends of the voltage regulating amplifier are connected with input ends of the filter amplifier through a sixth capacitor and a sixth resistor respectively.

9. The ferromagnetic detection system for a security column for a nuclear magnetic resonance room according to claim 6, characterized in that, The voltage conditioning amplification module further comprises an eleventh resistor and a ninth capacitor, an output end of the filter amplifier is connected with a first end of the eleventh resistor, a first end of the ninth capacitor is connected with the ground, and second ends of the ninth capacitor and the eleventh resistor are connected with an alarm device in common.

10. The ferromagnetic detection system for a security column for a nuclear magnetic resonance room according to claim 1, characterized in that, The first column and the second column are used to be arranged on two sides of a door of a nuclear magnetic resonance room, and the proximity detection device is arranged on the first column and the second column. The proximity detection device and the ferromagnetic detection device are electrically connected, and when a patient approaches the door of the nuclear magnetic resonance room, the ferromagnetic detection device enters a working state. The proximity detection device comprises a millimeter wave radar.

Images