JP2006222417A - System and method for monitoring superconductive magnet device and mri device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconductive magnet device monitoring system, a superconductive magnet device monitoring method, and an MRI device capable of detecting the abnormality of a liquid helium state even in the case that the inside of a liquid helium vessel is occluded by solid air, and capable of performing maintenance on a suitably timely basis. <P>SOLUTION: This superconductive magnet device monitoring system is equipped with a detective means 133, a remaining quantity prediction means 311 and an output means 420. The detective means 133 detects the remaining quantity of liquid helium stored in a liquid helium vessel 120 of a superconductive magnet device 110 that stores liquid helium in which superconductive coils are immersed. The remaining quantity prediction means 311 computes the predicted value of the remaining quantity based on the remaining quantity of the liquid helium tentatively detected by the detective means 133. The output means 420 outputs the monitoring information of the superconductive magnet device 110 based on the detected remaining quantity and the predicted value of the remaining quantity of the liquid helium. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a superconducting magnet apparatus monitoring system, a superconducting magnet apparatus monitoring method, and an MRI apparatus for monitoring a liquid helium immersion cooling type superconducting magnet.

  In recent years, various apparatuses such as a magnetic resonance imaging (MRI) apparatus to which a liquid helium immersion cooling type superconducting magnet is applied have been widely used. This type of superconducting magnet is equipped with a container for storing cryogenic liquid helium (liquid helium container), and the superconducting state is realized by immersing and cooling the superconducting coil in this liquid helium container. (For example, refer to Patent Document 1).

  Conventionally, in order to monitor the state of liquid helium in the container, a pressure gauge that measures the internal pressure of the liquid helium container, or a liquid level gauge (level sensor, probe, etc.) that measures the remaining amount of liquid helium ) Etc. are used. As the pressure gauge, a mechanical pressure gauge, an electronic pressure transducer, or the like is applied (for example, see Patent Document 2).

  In addition, the liquid level gauge includes a composite wire composed of a superconductor and a normal conductor disposed so as to pass through the liquid level of liquid helium, and measures the resistance value by heating the composite wire. The measurement results are shown for the length of the part of the composite wire immersed in liquid helium (the part where the superconductor is in the superconducting state) and the part where the part is not immersed (the part where the superconductor is in the normal conducting state). For example, a technique for obtaining the liquid level (remaining amount) of liquid helium by converting the ratio to the length is used (see, for example, Patent Document 3).

  Such a pressure gauge and a liquid level gauge are generally provided in a service port (also called a service turret) of a liquid helium container. The service port is used when a current lead is attached to the superconducting coil inside the liquid helium container, when liquid helium is replenished, or when gas helium inside the container is discharged to the outside (see, for example, Patent Document 4). .

  FIG. 12 shows a schematic configuration of a conventional liquid helium container. A liquid helium container 1000 shown in the figure has a container body 1001 and a service port 1100. The container body 1001 has a double structure that forms a vacuum layer in order to reduce heat propagation inside and outside the container. A superconducting coil is immersed in the liquid helium H stored in the container main body 1001 and kept at a very low temperature. The container body 1001 is formed with a communication pipe 1002 connected to the service port 1100.

  The service port 1100 includes an opening / closing portion 1110 that is opened and closed when a current lead is connected to the superconducting coil or when liquid helium is replenished, a pressure gauge 1120, and gas helium in the container main body 1001 from an outlet 1131. A discharge pipe 1130 for discharging is provided. A backflow prevention valve 135 is attached in the middle of the discharge pipe 134.

  In such a liquid helium container 1000, when outside air flows from the service port 1100, the outside air may freeze and become solid air X, which may block the communication pipe 1002. Then, the pressure gauge 1120 cannot measure the pressure in the container main body 1001 and cannot detect it even if a pressure abnormality occurs inside, so that there is a possibility that maintenance cannot be performed at a suitable timing.

  In addition, considering the physical characteristics of liquid helium that the temperature rises in response to an increase in the pressure in the container, the container can be used to determine the risk of quenching when using a permanent current (permanent current mode quench). Although it is effective to monitor the internal pressure, as described above, if the communication tube 1002 is clogged, the pressure abnormality cannot be detected.

In order to detect the internal pressure of the liquid helium container, a pressure gauge may be installed inside the container. However, in that case, since the heat outside the container enters the container through the pressure gauge, boil-off of liquid helium is promoted, so the replenishment amount and replenishment frequency of liquid helium increases. As a result, it is inferred that the running cost increases. Therefore, it is considered impractical to install a means for detecting the internal pressure of the liquid helium container inside the container.
JP 2001-143922 A JP 2003-69092 A JP-A-6-307914 JP-A-7-183116

  The present invention has been made in view of such circumstances, and even when the liquid helium container is closed with solid air, an abnormality in the state of liquid helium can be detected, and maintenance is performed at a suitable timing. It is an object of the present invention to provide a superconducting magnet device monitoring system, a superconducting magnet device monitoring method, and an MRI apparatus.

  In addition, the present invention can detect abnormalities in the state of liquid helium even when the liquid helium container is blocked by solid air, and grasps the danger of magnet destruction and permanent current mode quenching due to abnormal pressure. It is another object of the present invention to provide a superconducting magnet device monitoring system, a superconducting magnet device monitoring method, and an MRI apparatus.

  In order to achieve the above object, a superconducting magnet device monitoring system according to the present invention provides a liquid helium container for a superconducting magnet device for storing liquid helium immersed in a superconducting coil as described in claim 1. Based on a detection means for detecting the remaining amount of liquid helium stored in the storage unit, and a remaining amount of liquid helium preliminarily detected by the detection means, a remaining amount prediction value indicating a predicted value of the remaining amount is calculated. And a output means for outputting monitoring information of the superconducting magnet device based on the detected remaining amount of liquid helium and the estimated remaining amount of liquid helium.

  Moreover, the superconducting magnet apparatus monitoring method according to the present invention provides a liquid for a superconducting magnet apparatus for storing liquid helium in which a superconducting coil is immersed, in order to achieve the above-described object. Detecting a remaining amount of the liquid helium stored in the helium container; calculating a remaining amount predicted value indicating a predicted value of the remaining amount based on a preliminarily detected remaining amount of liquid helium; And a step of outputting monitoring information of the superconducting magnet device based on the detected remaining amount of liquid helium and the estimated remaining amount of liquid helium.

  In order to achieve the above object, an MRI apparatus according to the present invention includes a static magnetic field coil that applies a static magnetic field to a subject and a superconducting magnet that monitors the static magnetic field coil, as described in claim 17. An apparatus monitoring system; a gradient coil for applying a gradient magnetic field to the subject to which the static magnetic field is applied; an RF coil for receiving a nuclear magnetic resonance signal emitted from the subject; Reconstructing means for reconstructing a tomographic image of the subject based on the nuclear magnetic resonance signal, and the superconducting magnet device monitoring system is a liquid helium liquid that immerses the superconducting coil constituting the static magnetic field coil Based on the detection means for detecting the remaining amount in the helium container and the remaining amount of liquid helium preliminarily detected by the detection means, a predicted remaining amount value indicating the predicted value of the remaining amount is calculated. A battery remaining capacity predicting means, is characterized in that an output means for the the detected remaining amount of the liquid helium on the basis of the remaining amount predicted value to output a monitoring information of the superconducting magnet apparatus.

  According to the superconducting magnet apparatus monitoring system, superconducting magnet apparatus monitoring method, and MRI apparatus according to the present invention, the state of liquid helium (especially pressure and temperature) even when the liquid helium container is closed with solid air. Anomalies can be detected. As a result, maintenance can be performed at a suitable timing, and the danger of magnet destruction and the danger of permanent current mode quenching can be grasped.

  Liquid helium is known to increase in volume as the pressure increases. The present invention uses this characteristic to detect an abnormality in the remaining amount of liquid helium as a pressure abnormality by associating the detection result of the remaining amount of liquid helium with the pressure in the liquid helium container. Furthermore, liquid helium has a characteristic that the temperature increases as the pressure increases, and the present invention uses this characteristic and the above-described characteristics to relate the remaining amount of liquid helium to the temperature. The remaining amount abnormality is detected as a temperature abnormality.

  An example of a preferred embodiment of a superconducting magnet device monitoring system and a superconducting magnet device monitoring method executed thereby will be described in detail with reference to the drawings. In the following embodiment, the system is applied to an MRI apparatus.

(System configuration)
First, the configuration of the superconducting magnet device monitoring system according to the present embodiment will be described with reference to FIG. FIG. 1 shows a schematic configuration of a superconducting magnet device monitoring system 1 for monitoring a superconducting magnet device 110 applied to the MRI apparatus 100.

  Here, a schematic configuration of the MRI apparatus 100 that creates a tomographic image of a subject will be briefly described with reference to FIG. The MRI apparatus 100 includes a static magnetic field coil 140, a gradient magnetic field coil 150, an RF (Radio Frequency) coil 160, a coil control unit 170, and a reconstruction unit 180, as in the conventional case. The static magnetic field coil 140 is disposed in a liquid helium container 120 described later. The superconducting magnet device 110 of this embodiment includes a static magnetic field coil 140.

  The static magnetic field coil 140 includes a superconducting coil for generating a uniform and stable static magnetic field and applying it to a subject. The gradient magnetic field coil 150 applies a gradient magnetic field for identifying the position in the subject to the subject to which the static magnetic field is applied by the static magnetic field coil 140. The RF coil 160 receives a nuclear magnetic resonance signal emitted from the subject. This nuclear magnetic resonance signal is emitted corresponding to a high-frequency magnetic field (RF magnetic field) applied to the subject by the RF coil 160 itself or another RF coil.

  The coil control unit 170 supplies power to each of the static magnetic field coil 140, the gradient magnetic field coil 150, and the RF coil 160, controls the application timing of the magnetic field by each of the gradient magnetic field coil 150 and the RF coil for generating nuclear magnetic resonance signals, etc. I do.

  The reconstruction unit 180 receives the nuclear magnetic resonance signal received by the RF coil 160 and reconstructs a tomographic image of the subject based on the nuclear magnetic resonance signal.

  The superconducting magnet apparatus monitoring system 1 includes a console 200 for operating the MRI apparatus 100, a server 300 that provides a monitoring service for the MRI apparatus 100 (including the superconducting magnet apparatus 110) via the Internet 500, and the server 300. And a monitoring terminal 400 connected to the. The superconducting magnet device monitoring system 1 includes a liquid level gauge provided in the superconducting magnet device 110 (described later).

  The console 200 and the server 300 are communicably connected via the Internet 500. In FIG. 1, only one MRI apparatus 100 is shown for simplification of illustration, but the server 300 can provide services to an arbitrary number of MRI apparatuses.

  The MRI apparatus 100 and the console 200 are installed in a medical institution such as a hospital. The server 300 and the monitoring terminal 400 are installed in a maintenance service provider company of the MRI apparatus 100, for example.

  In addition to various operations of the MRI apparatus 100, the console 200 stores data representing the state of the superconducting magnet apparatus 110, for example, measurement data such as the internal pressure of the liquid helium container and the liquid level, etc. periodically or as required. To 300. Note that this measurement data transmission processing may be performed by a dedicated data transmission device. The server 300 performs analysis processing of measurement data from the console 200, management of various data related to the maintenance service of the MRI apparatus 100, and the like. The monitoring terminal 400 acquires measurement data stored in the server 300 and displays it on a monitor, and performs various data input processing, rewriting processing, and the like in response to an operator request.

(Configuration of superconducting magnet device)
Next, the configuration of the superconducting magnet device 110 will be described. The superconducting magnet device 110 has a configuration similar to that of the prior art, and includes a liquid helium container for storing liquid helium and a superconducting coil immersed in the liquid helium. Hereinafter, an example of the configuration of the liquid helium container related to the present invention will be described with reference to FIG.

  The liquid helium container 120 shown in FIG. 2 has a container body 121 and a service port 130. The container main body 121 has a double structure that forms a vacuum layer, and reduces heat propagation between the inside and the outside of the container. A superconducting coil C is installed in the container body 121 and is immersed in liquid helium H stored in the container body 121 and kept at a very low temperature. The container main body 121 is formed with a communication pipe 122 connected to the service port 130.

  The service port 130 is provided with an opening / closing part 131, a pressure gauge 132, a liquid level gauge 133, and a discharge pipe 134. The opening / closing part 131 is opened / closed when a current lead is connected to the superconducting coil C or when liquid helium H is replenished in the container body 121. The pressure gauge 132 is provided at the distal end portion of the pressure detection conduit 132 branched from the communication pipe 122. The pressure gauge 132 is constituted by a mechanical pressure gauge or an electronic pressure transducer as in the conventional case.

  The level gauge 133 is an example of “detection means”, and a level gauge main body 133a installed outside the liquid helium container 120, a superconductor installed in the liquid helium container 120, and It is configured to include a normal conductor composite wire 133b and a measurement line 133c connecting them. The measurement line 133c connects the liquid level meter main body 133a and the composite wire 133b through a measurement line port 133d formed on the wall surface of the connecting pipe 122. The composite wire 133b is installed along a direction substantially perpendicular to the liquid surface Ha of the liquid helium H. The level gauge main body 133a applies a voltage to the composite wire 133b, and measures the resistance value at that time, thereby detecting the level of the liquid level Ha.

  The detection result by the liquid level meter 133 is displayed as a normal percentage display, that is, 0% when the liquid level Ha is at the lower end of the composite wire 133b and 100% when it is at the upper end. The detection result may be displayed by the distance (centimeter, inch, etc.) from the lower end (upper end) of the composite wire 133b to the liquid level Ha, or the remaining amount (liter) calculated from the liquid level detection value is displayed. You may make it do.

  The discharge pipe 134 is for discharging the gas helium inside the container main body 121 from the discharge port 134 a, and is formed to branch from the communication pipe 122. A check valve 135 is provided in the middle of the discharge pipe 134. When the pressure of gas helium in the container body 121 exceeds a predetermined value, the gas helium is passed in the direction of the discharge port 134a. Further, the backflow prevention valve 135 prevents outside air from flowing into the container main body 121.

(Control system configuration)
Next, the configuration of the control system of the superconducting magnet device monitoring system 1 will be described. FIG. 3 shows an example of the configuration of the control system of the system 1.

(console)
The console 200 is provided with a control unit 210, a monitor 220, an input device 230, and a communication unit 240. The monitor 220 is a display device such as an LCD or a CRT. The input device 230 is an arbitrary input device for the operator of the console 200 to perform various operations and data input, such as a keyboard, a mouse, a trackball, and an operation panel. The communication unit 240 includes a modem for performing data communication via the Internet 500.

  The control unit 210 of the console 200 includes an arithmetic control device such as a CPU and a storage device such as a RAM, a ROM, and a hard disk drive. In this storage device, various computer programs are stored in advance. The CPU of the control unit 210 executes this computer program, thereby controlling the operation of the MRI apparatus 100, controlling the measurement process by the pressure gauge 132 and the liquid level gauge 133, and controlling the communication process including the transmission process of the measurement data. Are executed respectively.

(server)
The server 300 includes a control unit 310, a database 320, and a communication unit 330. The database 320 is a mass storage device that stores various data related to the maintenance service of the MRI apparatus 100. The communication unit 330 includes a modem for Internet connection and a network adapter for performing data communication with the monitoring terminal 400 via a communication line such as a LAN.

  The control unit 310 of the server 300 includes an arithmetic control device such as a CPU and a storage device such as a RAM, a ROM, and a hard disk drive, and a computer program for maintenance service is stored in the storage device. This control unit 310 performs control of communication processing via the Internet 500, control of data storage processing and data read processing for the database 320, control of communication processing with the monitoring terminal 400, and the like.

  Furthermore, the control unit 310 includes a remaining amount prediction unit 311, a difference calculation unit 312, and a determination unit 313 as a configuration for monitoring the internal pressure of the liquid helium container 120. Each of these units 311 to 313 is configured by a CPU that executes the computer program.

  Based on the remaining amount of liquid helium H detected by the liquid level meter 133, the remaining amount predicting unit 311 performs a process of calculating a remaining amount predicted value representing a future transition (predicted value) of the remaining amount. This calculation process is performed as follows, for example.

  Here, it is assumed that the level of the liquid surface Ha of the liquid helium H is detected a plurality of times by the liquid level gauge 133 as a premise of the calculation process. This liquid level detection is performed, for example, once a day for one month (about 30 times in total). Further, the relationship between the level of the liquid level Ha and the remaining amount of the liquid helium H depends only on the installation position of the liquid level meter 133 and the size and form of the internal region of the liquid helium container 120, and the relationship Is known. That is, the remaining amount of liquid helium H can be obtained from the level of the liquid level Ha, and vice versa.

  The remaining amount predicting unit 311 calculates a boil-off-rate (BOR) of the liquid helium H based on a plurality of detection results obtained by the liquid level meter 133. B. O. R. Is an index representing the rate of decrease in the amount of liquid helium due to vaporization. If the amount of change in liquid helium H at time Δt is ΔV, B. O. R. = ΔV / Δt. As can be seen from this definition, B.I. O. R. Is negative. Here, Δt is, for example, one day, one week, one month, etc. O. R. Represents the amount of decrease in liquid helium H during one day, one week, and one month, respectively.

  Here, since the relationship between the remaining amount of liquid helium H and the level of the liquid level Ha is known as described above, the displacement level ΔL of the liquid level at the time Δt is used to determine the B.P. O. R. May be requested. For example, when the internal region of the liquid helium container 120 is a rectangular shape (see FIG. 2) and the bottom area is S, ΔV = S × ΔL. O. R. = (S × ΔL) / Δt. When the shape of the inner region of the liquid helium container 120 changes in the length direction of the composite wire 133b of the liquid level gauge 133 (for example, when the inner shape is a sphere), ΔV is considered in consideration of the degree of change. The relationship with ΔL is defined.

  The remaining amount predicting unit 311 further calculates the calculated B.P. O. R. Referring to FIG. 4, a predicted remaining amount of liquid helium H in the future is calculated. B. O. R. An example of the predicted remaining amount of liquid helium H based on FIG. 4 is shown in FIGS. Note that here, the temporal change prediction of the remaining amount V of the liquid helium H is used, but it is also possible to use the temporal change prediction of the level of the liquid surface Ha of the liquid helium H.

  The remaining amount prediction value V (t) shown in FIG. O. R. When the remaining amount prediction value is calculated from the value of O. R. The mode of the remaining amount predicted value obtained when the remaining amount predicted value is calculated using the average value of the values or the like is shown.

(Where t (n + 1) −tn = Δt). O. R. Obtained from the value of B. at t = 0 to t1. O. R. = ΔV1 / Δt, B. at t = t1 to t2. O. R. = ΔV2 / Δt,... Is used to predict the remaining amount taking into account the change in the decrease rate of liquid helium H over time.

  In consideration of the prediction accuracy, it is desirable to apply the remaining amount prediction value of FIG. 5 rather than the remaining amount prediction value of FIG. Here, in FIG. 5, two B.B. O. R. Only B. is used for calculating the remaining amount prediction value. O. R. The number of is arbitrary. For example, as described above, when the liquid level is detected once a day for one month, about 30 B.C. O. R. Based on the above, the remaining amount prediction value is calculated.

  The control unit 310 sets an allowable range of difference with respect to the calculated remaining amount predicted value V (t) (sometimes referred to as an allowable difference range). This allowable difference range is, for example, the amount of liquid helium corresponding to 1% of the value detected by the liquid level meter 133. The allowable difference range may use a preset value, or may be set individually for each calculated remaining amount predicted value V (t).

  FIG. 6 shows an example of a difference allowable range corresponding to the remaining amount prediction value V (t) in FIG. The allowable difference range shown in FIG. 6 is set by the allowable range upper limit U (t) and the allowable range lower limit D (t) of the remaining amount at time t. Here, the difference between the remaining amount prediction value V (t) and the allowable range upper limit U (t) and the difference between the remaining amount prediction value V (t) and the allowable range lower limit D (t) may be equal. (For example, the upper limit and the lower limit are each 1%) and may be different (for example, the upper limit is 1%, the lower limit is 1.5%, etc.). Further, only one of the allowable range upper limit U (t) and the allowable range lower limit D (t) may be set as necessary.

  Next, the difference calculation unit 312 will be described. The difference calculation unit 312 performs a process of calculating a difference between the remaining amount of liquid helium H based on the new detection result by the liquid level meter 133 and the remaining amount prediction value calculated by the remaining amount prediction unit 311. For example, assuming that the remaining amount of liquid helium H detected at time t = s is Vs, the difference calculation unit 312 calculates the remaining amount Vs and a predicted remaining amount V (s) corresponding to time t = s. The difference δV (s) is calculated.

  Note that the difference calculation by the difference calculation unit 312 may be to obtain an absolute value δV (s) = | Vs−V (s) | of the difference between the remaining amount Vs and the remaining amount predicted value V (s). The difference δV (s) = Vs−V (s) between the remaining amount Vs and the remaining amount predicted value V (s) may be obtained. In particular, the difference between the remaining amount predicted value V (t) and the allowable range upper limit U (t) is equal to the difference between the remaining amount predicted value V (t) and the allowable range lower limit D (t). It is preferably used when it is set. On the other hand, the latter is preferably used when these differences are set differently.

  The determination unit 313 performs a process of determining whether the difference δV (s) calculated by the difference calculation unit 312 is included in the above-described difference allowable range. More specifically, the determination unit 313 determines whether or not the calculated difference δV (s) is equal to or less than the liquid helium amount corresponding to, for example, 1% of the detection value of the liquid level meter 133. Referring to FIG. 6, when it is determined that the difference δV (s) is equal to or less than 1% of the liquid level detection value, the remaining amount Vs of liquid helium H at time t = s is the allowable range lower limit D (s). It is included in the permissible range upper limit U (s). On the other hand, when it is determined that the difference δV (s) exceeds 1% of the liquid level detection value, the remaining amount V (s) is not included in the allowable range.

(Monitoring terminal)
The monitoring terminal 400 includes a control unit 410, a monitor 420, an input device 430, and a communication unit 440. The monitor 420 and the input device 430 are the same as those of the console 200. The communication unit 440 includes a network adapter for performing data communication with the server 300 via a communication line such as a LAN.

  The control unit 410 of the monitoring terminal 400 includes an arithmetic control device such as a CPU and a storage device such as a RAM, a ROM, and a hard disk drive. In this storage device, various computer programs are stored in advance. The CPU of the control unit 410 processes the various data related to the maintenance service of the MRI apparatus 100 by executing this computer program. When the server 300 and the monitoring terminal 400 constitute a server-client system, the CPU of the control unit 410 can perform the same processing based on a computer program stored in the server 300.

(Processing procedure)
Processing executed by the superconducting magnet apparatus monitoring system 1 configured as described above will be described with reference to FIG. The flowchart of FIG. 7 shows an example of a series of processing procedures from the start of use of the superconducting magnet device 100 until the abnormality of the liquid helium state is detected and maintenance is performed.

  The liquid helium container 120 is replenished with liquid helium H and the use of the superconducting magnet device 110 (MRI apparatus 100) is started (S1). After the start of use, the liquid level level (remaining amount) of the liquid helium H is preliminarily detected by the liquid level meter 133 at a predetermined interval (for example, one day interval) for a predetermined period (for example, one month) (S2). This detection process is executed under the control of the control unit 210 of the console 200. Each detection result is transmitted to the server 300 by the console 200 and accumulated in the database 320.

  When a predetermined number (for example, about 30) of preliminary detection results of the remaining amount of liquid helium H is obtained, the remaining amount prediction unit 311 of the server 300 determines the B.B. O. R. Is calculated (S3), and a predicted remaining amount V (t) as shown in FIG. 4 or 5 is calculated (S4). The controller 310 sets an allowable range of difference with respect to the remaining amount predicted value V (t) (S5). The remaining amount prediction value V (t) calculated in step S4 and the allowable difference range set in step S5 are stored in the database 320, respectively. If the allowable difference range is set as a default, step S5 need not be performed.

  The above processing procedure is a preliminary processing for monitoring the remaining amount of liquid helium H. Hereinafter, the actual monitoring process of liquid helium H will be described.

  At time t = s, the liquid level gauge 133 detects the liquid level (remaining amount Vs) of the liquid helium H in the liquid helium container 120 (S6). The detection result Vs is sent to the server 300. The detection by the liquid level meter 133 is periodically executed, for example, every week under the control of the control unit 210 of the console 200.

  The difference calculation unit 312 of the server 300 calculates the new detection result Vs of the remaining amount of liquid helium H and the value V (s) at t = s of the remaining amount predicted value V (t) calculated in step S4. The difference δV (s) is calculated (S7).

  The determination unit 313 determines whether the difference δV (s) is included in the allowable difference range set in step S5 (S8). If it is determined that it is included (S8; Y), no special process is performed, and a standby state is set until the next detection by the liquid level meter 133 (S9).

  Here, when it is determined that the difference δV (s) is included in the allowable difference range (S8; Y), the monitor 420 of the monitoring terminal 400 indicates “the liquid helium state is normal” according to an instruction from the server 300. Etc. can be displayed. A similar message may be displayed on the monitor 220 of the console 200.

  On the other hand, when it is determined that the difference δV (s) is not included in the allowable difference range (S8; N), the control unit 310 of the server 300 transmits a control signal to the monitoring terminal 400 to indicate “liquid helium A warning message such as “A problem has occurred in the state” is displayed (S10). At this time, a similar warning message may be displayed on the monitor 220 of the console 200. A warning sound or the like may be output. Furthermore, an alarm message can be transmitted by e-mail to a terminal device (such as a mobile phone or PDA) carried by a service engineer. An arbitrary method can be used for alerting in step S10.

  The service engineer performs maintenance of the liquid helium container 120 in response to the warning message or warning sound (S11). In this maintenance, confirmation of icing condition and blockage condition in the liquid helium container 120, removal of icing solid air, confirmation of the service port 130, etc. are performed. This is the end of the liquid helium H monitoring process.

  Here, the remaining amount detection value (step S6) obtained in the current monitoring process can be used to correct the remaining amount prediction value V (t) and used for the next monitoring process.

  The monitor 420 that displays a warning message in step S10, a sound output device (speaker, sound output circuit, etc.) that outputs a warning sound or the like, and a portable terminal device are examples of the “notification means” of the present invention.

(Function and effect)
The physical characteristics of liquid helium, which is the premise of the operational effects of this embodiment, will be described. [Background Art] As mentioned above, when the pressure in the liquid helium container 120 increases, the temperature of the liquid helium H also increases. Further, the pressure increase in the liquid helium container 120 corresponds to an increase in the amount (volume) of liquid helium. FIG. 8 shows the relationship (actual measurement value) between the amount of liquid helium H (detected value by the liquid level meter 133) and the internal pressure of the liquid helium container 120. In FIG. 8, the detection value (indicated value) of the liquid level gauge 133 changes substantially linearly in the range of about 43.2% to 45.8%, corresponding to the range of the internal pressure of the container of about 5 kPa to 35 kPa. The state of doing is shown. By using such characteristics of liquid helium, the following effects can be obtained.

  According to the superconducting magnet device monitoring system 1 of the present embodiment, first, the liquid helium H remaining amount prediction value V (t) is obtained from the preliminary detection result of the liquid helium H remaining amount by the liquid level gauge 133. This remaining amount prediction value V (t) is a prediction of an appropriate remaining amount of liquid helium H at any future time t. Further, at an arbitrary time t, an allowable difference range of the remaining amount Vt of liquid helium H with respect to the estimated remaining amount V (t) is set. The above is preliminary processing. In the actual monitoring process (time t = s), a warning message or the like when the difference δV (s) between the detection result Vs of the remaining amount of liquid helium H and the predicted remaining amount V (s) exceeds the allowable difference range. Is notified.

  In this embodiment, the allowable difference range is set to be equivalent to 1% of the detected value of the liquid level meter 133. Referring to FIG. 8, the allowable difference in the container internal pressure corresponding to the detected value of 1% is about 2.3 kPa. The allowable difference range of the remaining amount V (t) of the liquid helium H is set according to the allowable difference range of the internal pressure of the container.

  That the difference δV (s) exceeds the allowable range means that the difference in the container internal pressure exceeds the allowable range. Such an abnormality in the internal pressure of the container suggests a possibility that the liquid helium container 120 is clogged with solid air (see FIG. 12). In addition, the occurrence of blockage is caused by the inflow of outside air from the service port 130, the failure of the backflow prevention valve 135, the risk of magnet destruction due to pressure abnormality, and the risk of permanent current mode quenching due to temperature rise. Suggest an increase.

  Therefore, according to the present embodiment, even when the communication tube 122 of the liquid helium container 120 is clogged with solid air, a pressure abnormality inside the container can be detected, so that maintenance can be performed at a suitable timing. it can. In addition, since the danger of magnet destruction and the danger of permanent current mode quenching can be grasped, it is possible to take early measures. In addition, there is no increase in running cost in system operation.

  Furthermore, some conventional superconducting magnet devices have a liquid level gauge in the liquid helium container. However, when this embodiment is applied to such a superconducting magnet device, it is necessary to add new hardware. As a result, the cost for introducing the system is reduced.

(Modification)
The configuration described above is one configuration example for carrying out the present invention, and various modifications can be made within the scope of the gist of the present invention. For example, the following modifications can be implemented.

  In the above embodiment, whether or not there is an abnormality in the liquid helium container is determined depending on whether or not the difference δV (s) in the remaining amount Vs with respect to the estimated remaining amount V (s) at time t = s is within an allowable range. Although it is determined, for example, it is also possible to determine whether there is an abnormality as follows.

  FIG. 9 shows the configuration of the control system of the superconducting magnet device monitoring system of this modification. This modification has a configuration substantially similar to that of the above-described embodiment shown in FIG. The only difference from the above embodiment is that the control unit 310 of the server 300 includes an allowable range setting unit 314 and a determination unit 315.

  The allowable range setting unit 314 performs a process of setting a remaining amount allowable range for the remaining amount predicted value V (t) calculated by the remaining amount predicting unit 311. The allowable range setting unit 314 adds, for example, a preset remaining amount difference (equivalent to 1% of the detection value of the liquid level meter 133) to the calculated remaining amount predicted value V (t). And / or subtracting the permissible range upper limit U (t) and / or permissible range lower limit D (t) (see the graph of FIG. 6).

  Unlike the determination unit 313 in the above embodiment, the determination unit 315 has the remaining amount Vs of liquid helium H detected by the liquid level meter 133 at the time t = s within the allowable range set by the allowable range setting unit 314. Determine whether it is included. That is, for example, when both the upper limit U (t) and the lower limit D (t) of the allowable range are set, the determination unit 315 satisfies D (s) ≦ Vs ≦ U (s) at time t = s. Judge whether there is. When only one of the upper limit U (t) and the lower limit D (t) is set, it is determined whether Vs ≦ U (s) or Vs ≧ D (s).

  The flowchart of FIG. 10 shows an example of a processing procedure according to this modification. In this flowchart, the same processes as those in the above embodiment are denoted by the same reference numerals. For those processes, refer to the description of the above embodiment, and a detailed description thereof will be omitted.

  The processing procedure of this modification is the same as that of the above embodiment until the calculation of the remaining amount prediction value V (t) in step S4. The allowable range setting unit 314 sets the allowable range of the remaining amount for the calculated remaining amount predicted value V (t) (S21). The set remaining amount allowable range is stored in the database 320.

  When the liquid level (remaining amount Vs) of the liquid helium H in the liquid helium container 120 is detected at time t = s (S6), the determination unit 315 determines that the newly detected remaining amount Vs is a step. It is determined whether it is included in the remaining amount allowable range set in S21 (S22). If it is determined that it is included (S22; Y), it will be in a standby state until the next detection by the liquid level meter 133 (S9).

  On the other hand, when it is determined that the remaining amount V (s) is not included in the remaining amount allowable range (S22; N), the control unit 310 of the server 300 causes the monitoring terminal 400 to output a warning message or a warning sound ( S10). The service engineer performs maintenance of the liquid helium container 120 in response to the warning message or warning sound (S11).

  According to this modification, as in the above embodiment, even if the liquid helium container 120 is clogged with solid air, the container internal pressure or temperature is abnormal based on the abnormality of the remaining amount of liquid helium H. Therefore, maintenance can be performed at a suitable timing, and the danger of magnet destruction and the danger of permanent current mode quenching can be known.

(Other variations)
In the above embodiment, the remaining amount prediction unit 311, the difference calculation unit 312, and the determination unit 313 are provided in the server 300, but these units may be provided in the console 200 or the monitoring terminal 400. For example, when these units are provided in the console 200, the determination result by the determination unit 313 is transmitted to the server 300, and a warning message display by the monitoring terminal 400 is executed. Further, it is not necessary that all these units are provided in the same apparatus. Such a modification is the same for the above modification.

  The system according to the present invention need not include all of the console, the server, and the monitoring terminal, and may include other devices. Further, the communication process with the maintenance service company does not need to be performed by the console. For example, a server on the medical institution side may communicate with the maintenance service company side. Further, communication processing such as a modem can be directly connected to a superconducting magnet apparatus (MRI apparatus or the like) for communication processing. Furthermore, it is also possible to connect a computer device for maintenance service to the superconducting magnet device, and to perform operation control of a liquid level gauge, pressure gauge, etc., and communication processing with the maintenance service company by this computer device.

  The “MRI apparatus” according to the present invention includes an apparatus having a system configuration as shown in FIG. 3 or FIG.

  In addition, the superconducting magnet device monitoring system 1 does not necessarily have to output the determination results in the determination units 313 and 315 as monitoring information of the superconducting magnet device 110. For example, the remaining amount of liquid helium detected by the detecting means such as the liquid level meter 133 and the remaining amount predicted value calculated by the remaining amount predicting unit 311 itself or information obtained from these data is stored in the monitor 420 as a superconducting magnet device. 110 may be displayed as monitoring information.

  In this case, an abnormality of the superconducting magnet device 110 is detected by referring to the monitoring information of the superconducting magnet device 110 displayed by the user. Therefore, it is desirable to separately prepare a determination table for determining whether or not the superconducting magnet device 110 is abnormal from the liquid helium remaining amount prediction value and the detected liquid helium remaining amount in advance.

  This determination table shows, for example, the upper and lower limits of the liquid helium remaining amount prediction value and the allowable liquid helium remaining amount value, or the liquid helium deviation amount (difference) Or a ratio value).

  If the user can refer to the determination table as paper or electronic information, it is not necessary to provide the superconducting magnet device monitoring system 1 with components such as the determination units 313 and 315, and the superconducting magnet device monitoring system 1 can be simplified. It is possible to connect to Furthermore, it is possible to save the user from having to specify the allowable range. Further, even when the allowable range of the remaining amount of liquid helium is different for each user or superconducting magnet device 110 or when the allowable range is changed later, a plurality of different allowable ranges are arbitrarily set as the determination table. Therefore, the parameter setting of the superconducting magnet device monitoring system 1 is not necessary and can be shared.

Schematic showing an example of the whole structure of embodiment of the superconducting magnet apparatus monitoring system which concerns on this invention. The schematic sectional drawing showing an example of the liquid helium container of the superconducting magnet apparatus monitored by embodiment of the superconducting magnet apparatus monitoring system which concerns on this invention. The block diagram showing an example of the composition of the control system of the embodiment of the superconducting magnet device monitoring system concerning the present invention. The graph for demonstrating the calculation method of the linear residual amount prediction value of liquid helium by embodiment of the superconducting magnet apparatus monitoring system which concerns on this invention. The graph for demonstrating the calculation method of the curve residual amount prediction value of liquid helium by embodiment of the superconducting magnet apparatus monitoring system which concerns on this invention. The graph showing an example of the tolerance | permissible_range with respect to the residual amount predicted value of liquid helium in embodiment of the superconducting magnet apparatus monitoring system which concerns on this invention. The flowchart showing an example of the process sequence performed by embodiment of the superconducting magnet apparatus monitoring system which concerns on this invention. The graph showing an example of the relationship between the residual amount of liquid helium and the internal pressure of a liquid helium container in embodiment of the superconducting magnet apparatus monitoring system which concerns on this invention. The block diagram showing an example of the structure of the control system of the modification of the superconducting magnet apparatus monitoring system which concerns on this invention. The flowchart showing an example of the process sequence performed by the modification of the superconducting magnet apparatus monitoring system which concerns on this invention. 1 is a block diagram showing a schematic configuration of an embodiment of an MRI apparatus to which a superconducting magnet apparatus monitoring system according to the present invention is applied. Sectional drawing showing schematic structure of the conventional liquid helium container.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Superconducting magnet apparatus monitoring system 100 MRI apparatus 110 Superconducting magnet apparatus 120 Liquid helium container 121 Container body 122 Connection pipe 130 Service port 131 Opening and closing part 132 Pressure gauge 133 Liquid level gauge 134 Discharge pipe 135 Backflow prevention valve 140 Static magnetic field coil 150 Gradient magnetic field Coil 160 RF coil 170 Coil control unit 180 Reconfiguration unit 200 Console 300 Server 310 Control unit 311 Remaining amount prediction unit 312 Difference calculation unit 313 Determination unit 314 Allowable range setting unit 315 Determination unit 320 Database 400 Monitoring terminal 420 Monitor 500 Internet C Superconducting coil H Liquid helium Ha Liquid level

Claims (17)

Detecting means for detecting the remaining amount of liquid helium stored in a liquid helium container of a superconducting magnet device for storing liquid helium immersed in the superconducting coil;
A remaining amount predicting unit that calculates a remaining amount predicted value indicating a predicted value of the remaining amount based on the remaining amount of liquid helium preliminarily detected by the detecting unit;
Output means for outputting monitoring information of the superconducting magnet device based on the detected remaining amount of liquid helium and the remaining amount prediction value;
A superconducting magnet device monitoring system comprising: The superconducting magnet apparatus monitoring system according to claim 1, wherein the output means is configured to output the remaining amount of liquid helium and the predicted remaining amount as the monitoring information. Difference calculating means for calculating a difference between the remaining amount of liquid helium newly detected by the detecting means after the preliminary detection and the estimated remaining amount corresponding to the calculated new detection time;
Judgment means for judging whether or not the calculated difference is included in a predetermined allowable range;
The output means is configured to output the determination result of the determination means as the monitoring information.
The superconducting magnet apparatus monitoring system according to claim 1. An allowable range setting means for setting an allowable range of the remaining amount for the calculated remaining amount predicted value;
Determination means for determining whether the remaining amount of liquid helium newly detected by the detection means after the preliminary detection is included in the set allowable range;
The output means is configured to output the determination result of the determination means as the monitoring information.
The superconducting magnet apparatus monitoring system according to claim 1. The preliminary detection of the remaining amount of liquid helium by the detection means is performed a plurality of times,
The remaining amount prediction means calculates a boil-off rate of liquid helium based on the plurality of remaining amounts obtained by the plurality of preliminary detections, and predicts the remaining amount based on the calculated boil-off rate. Configured to calculate a value,
The superconducting magnet apparatus monitoring system according to claim 1. 2. The superconducting magnet apparatus monitoring system according to claim 1, wherein the detecting means includes a liquid level gauge for detecting a liquid level of liquid helium stored in the liquid helium container. 4. The superconducting magnet apparatus monitoring system according to claim 3, wherein the output means includes notification means for performing notification when the determination means determines that the difference is not included in the predetermined allowable range. The said output means is provided with the alerting | reporting means which alert | reports when the remaining amount of the said liquid helium is not contained in the said tolerance | permissible_range set by the said judgment means. Superconducting magnet device monitoring system. Detecting the remaining amount of liquid helium stored in a liquid helium container of a superconducting magnet device for storing liquid helium immersed in the superconducting coil;
Calculating a remaining amount predicted value indicating a predicted value of the remaining amount based on a preliminarily detected remaining amount of liquid helium;
Outputting monitoring information of the superconducting magnet device based on the detected remaining amount of liquid helium and the remaining amount prediction value;
A superconducting magnet apparatus monitoring method comprising: The superconducting magnet device monitoring method according to claim 9, wherein the remaining amount of liquid helium and the predicted remaining amount are output as the monitoring information. Calculating a difference between the remaining amount of liquid helium newly detected after the preliminary detection and the predicted remaining amount corresponding to the calculated new detection time;
Determining whether the calculated difference falls within a predetermined tolerance range;
Outputting the result of the determination as the monitoring information;
The superconducting magnet apparatus monitoring method according to claim 9. Setting an allowable range of the remaining amount for the calculated remaining amount predicted value;
Determining whether the remaining amount of liquid helium newly detected after the preliminary detection is included in the set allowable range;
Outputting the result of the determination as the monitoring information;
The superconducting magnet apparatus monitoring method according to claim 9. The preliminary detection of the remaining amount of liquid helium is performed a plurality of times,
Calculating a boil-off rate of liquid helium based on a plurality of the remaining amount obtained by the preliminary detection of the plurality of times, and calculating the remaining amount prediction value based on the calculated boil-off rate,
The superconducting magnet apparatus monitoring method according to claim 9. The superconducting magnet apparatus monitoring method according to claim 9, wherein a liquid level of liquid helium stored in the liquid helium container is detected as the remaining amount by a liquid level gauge. The superconducting magnet apparatus monitoring method according to claim 11, wherein notification is performed when it is determined that the difference is not included in the predetermined allowable range. 13. The superconducting magnet device monitoring method according to claim 12, wherein notification is performed when it is determined that the remaining amount of liquid helium is not included in the set allowable range. A static magnetic field coil for applying a static magnetic field to the subject;
A superconducting magnet device monitoring system for monitoring the static magnetic field coil;
A gradient coil for applying a gradient magnetic field to the subject to which the static magnetic field is applied;
An RF coil for receiving a nuclear magnetic resonance signal emitted from the subject;
Reconstructing means for reconstructing a tomographic image of the subject based on the received nuclear magnetic resonance signal;
The superconducting magnet device monitoring system is:
Detecting means for detecting the remaining amount of liquid helium in the liquid helium container in which the superconducting coil constituting the static magnetic field coil is immersed;
A remaining amount predicting unit that calculates a remaining amount predicted value indicating a predicted value of the remaining amount based on the remaining amount of liquid helium preliminarily detected by the detecting unit;
Output means for outputting monitoring information of the superconducting magnet device based on the detected remaining amount of liquid helium and the remaining amount prediction value;
An MRI apparatus characterized by comprising:

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