JP3912887B2 - MR system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cooling device for an MR magnet unit in an MR system that provides diagnostic information such as MRI (magnetic resonance image) and frequency spectrum using a magnetic resonance phenomenon.
[0002]
[Prior art]
The MR magnet section in the MR system is equipped with a static magnetic field magnet, a gradient magnetic field coil, and an RF coil in order from the outside. Among them, the heat source that generates the most heat is a gradient coil that is repeatedly supplied with very high current pulses.
[0003]
In the conventional cooling device, the cooling unit in which the tube through which the coolant from the heat exchanger flows concentrates is provided close to the gradient coil so as to mainly cool the gradient coil as the heat source, or the gradient Molded integrally with the magnetic field coil. Further, in the conventional cooling device, a temperature sensor is attached in a return tube from the cooling unit to the heat exchanger, and the cooling capacity is adjusted by monitoring the temperature of the return coolant.
[0004]
In this conventional method for adjusting the cooling capacity, the response time of the monitor temperature to the temperature rise of the heat source, the response time until the temperature of the heat source actually decreases after the increase of the cooling capacity, and the heat generated in the heat source In consideration of the time required to conduct to the inner wall of the magnet opening closest to the subject or to the subject, it is necessary to cool early and early, which tends to result in excessive cooling. . Therefore, there is a problem that the running cost becomes high. In addition, a heat insulating structure that seems to be excessive is adopted between the heat source and the inner wall of the opening of the magnet part, leading to an increase in the size of the magnet part.
[0005]
[Problems to be solved by the invention]
The objective of this invention is providing the cooling device of the MR magnet part which can cool efficiently.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is provided with a static magnetic field magnet for generating a static magnetic field, a coil for generating a magnetic resonance signal from a subject, and provided between the static magnetic field magnet and the coil. housing the cooling unit for cooling the said a MR magnet unit having an opening for inserting a subject, and detecting means for detecting a temperature of the MR magnet portion of the opening in the wall, the opening in the wall And a cooling controller that controls the operation of the cooling unit housed in the MR magnet unit based on temperature.
In order to achieve the above object, an invention according to claim 6 is provided between a static magnetic field magnet for generating a static magnetic field, a gradient magnetic field coil for generating a gradient magnetic field, and between the static magnetic field magnet and the gradient magnetic field coil, A first cooling unit that cools the gradient magnetic field coil, an RF coil that transmits an RF pulse, a second cooling unit that is provided between the gradient magnetic field coil and the RF coil, and cools the RF coil; In the MR magnet part which accommodates the 1st detection means which detects the temperature of the said gradient magnetic field coil, the said static magnetic field magnet, the said gradient magnetic field coil, the said RF coil, the said 1st cooling part, and the said 2nd cooling part second detecting means for detecting the temperature of the opening in the wall, on the basis of the temperature of the gradient coil to control the operation of the first cooling section, the second based on the temperature of the opening in the wall Cooling Characterized by comprising a cooling controller for controlling the operation of.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a configuration of an MR magnet section cooling device according to an embodiment of the present invention. In the MR system that provides diagnostic information such as MRI (Magnetic Resonance Image) and frequency spectrum using the magnetic resonance phenomenon, the MR magnet unit 1 generates gradient magnetic field pulses and RF pulses in time series according to the pulse sequence. Is a main structure for generating and receiving a magnetic resonance signal, and has a substantially rectangular parallelepiped shape in which a cylindrical opening 2 for inserting a subject is formed substantially horizontally, and an opening from the outside The static magnetic field magnet 3, the gradient magnetic field coil 5, and the RF coil 7 are accommodated in order toward 2. A dotted-line ellipse is a region where the magnetic field strength changes linearly along each of the XYZ axes by the gradient coil 5, and imaging, that is, sampling of a magnetic resonance signal is possible in this region.
[0009]
The cooling device locally cools such an MR magnet part, and mainly cools the gradient magnetic field coil 5 as a heat source that generates the most heat by switching the gradient magnetic field pulse in the MR magnet part. Next, the first cooling unit 9 provided adjacent to the gradient magnetic field coil 5 or formed integrally with the gradient magnetic field coil 5, and the RF coil 7 located on the innermost side of the opening 2 of the MR magnet unit 1 are adjacent to each other. Or a second cooling part 11 formed integrally with the RF coil 7.
[0010]
The main body (cooling main body) 20 of the cooling device includes a first heat exchanger 23 and a second heat exchanger 25 with the cooling controller 21 as a control center.
The coolant is circulated through the cooling water tube 31 between the first heat exchanger 23 and the first cooling unit 9. The coolant is circulated between the second heat exchanger 25 and the second cooling unit 11 via the cooling water tube 33.
[0011]
The first temperature sensor 13 is attached to the gradient coil 5 as a heat source and is driven by the cooling controller 21 via the first cable 27 to detect the temperature of the gradient coil 5. The second temperature sensor 15 is mounted on the inner wall 17 of the opening that is located on the innermost side of the opening 2 of the MR magnet unit 1 and that may be in contact with the subject, and is connected to the cooling controller 21 via the second cable 29. To detect the temperature of the inner wall 17 of the opening. In general, the RF coil 7 is formed by embedding a coil wire material and molding reinforced plastic or the like into a cylindrical shape. Therefore, the opening inner wall 17 can be called the RF coil 7 itself or the inner wall of the RF coil 7.
[0012]
The cooling controller 21 adjusts the cooling capacity of the first heat exchanger 23 based on the temperature of the gradient magnetic field coil 5 as the heat source detected by the first temperature sensor 13. The cooling controller 21 adjusts the cooling capacity of the second heat exchanger 25 based on the temperature of the opening inner wall 17 detected by the second temperature sensor 15.
[0013]
FIG. 2 shows a control procedure for the heat exchangers 23 and 25 of the cooling controller 21. The cooling controller 21 controls the first heat exchanger 23 and the second heat exchanger 25 completely independently. Therefore, control with respect to each of the heat exchangers 23 and 25 is performed by another system | strain. First, a control system for the first heat exchanger 23 will be described.
[0014]
First, in step S <b> 11, the first temperature sensor 13 is driven by the cooling controller 21. Thereby, in step S12, the temperature T1 of the gradient coil 5 as a heat source is detected by the first temperature sensor 13. After step S12, the temperature detection of the gradient coil 5 by the first temperature sensor 13 is continued until the main power supply of the MR system is turned off.
[0015]
In step S13, the temperature T1 of the gradient magnetic field coil 5 detected by the first temperature sensor 13 takes into account the response time from the allowable temperature of the gradient magnetic field coil 5 according to the heat capacity of the gradient magnetic field coil 5 in the cooling controller 21. It is compared with a threshold value Tth1 that is set slightly lower.
[0016]
When the detected current temperature T1 is lower than the threshold value Tth1 (YES), in step S14, the cooling controller 21 decreases the cooling capacity of the first heat exchanger 23 or the first heat exchanger 23 Stop the cooling operation. The cooling capacity lowers the amount of cooling water output from the first heat exchanger 23 per unit time by lowering the output of the circulating pump of the cooling water equipped in the first heat exchanger 23. Reducing the output of the compressor for compressing the refrigerant equipped in the first heat exchanger 23 to increase the coolant temperature output from the first heat exchanger 23, or both Reduced by combined use. This prevents uneconomical overcooling of the gradient coil 5.
[0017]
The decrease in the cooling capacity of the first heat exchanger 23 by the cooling controller 21 is continued until NO in step S13, that is, T1 ≧ Tth1.
In step S13, when the detected current temperature T1 is higher than the threshold value Tth1 (NO), in step S15, the cooling controller 21 increases the cooling capacity of the first heat exchanger 23 or the first heat. The cooling operation of the exchanger 23 is started. The cooling capacity is to increase the amount of cooling water output from the first heat exchanger 23 per unit time by increasing the output of the cooling water circulation pump provided in the first heat exchanger 23. , Raising the output of the compressor for compressing the refrigerant equipped in the first heat exchanger 23 to lower the coolant temperature output from the first heat exchanger 23, or both Increased by combined use.
[0018]
The increase in the cooling capacity of the first heat exchanger 23 by the cooling controller 21 is continued until YES in step S13, that is, T1 <Tth1.
Next, a control system for the second heat exchanger 25 will be described.
First, in step S <b> 21, the second temperature sensor 15 is driven by the cooling controller 21. As a result, in step S22, the temperature T2 of the opening inner wall 17 that is closest to the subject and is likely to come into contact with the subject is detected by the second temperature sensor 15. After step S22, the temperature detection of the opening inner wall 17 by the second temperature sensor 15 is continued until the main power supply of the MR system is turned off.
[0019]
In step S23, the temperature T2 of the opening inner wall 17 detected by the second temperature sensor 15 is obtained when the subject touches the opening inner wall 17 in the cooling controller 21 or is exposed for a relatively long time. It is compared with a threshold value Tth2 that is set slightly lower in consideration of the response time than the upper limit temperature at which discomfort can occur.
[0020]
When the detected current temperature T2 is lower than the threshold value Tth2 (YES), in step S24, the cooling controller 21 decreases the cooling capacity of the second heat exchanger 25, or the second heat exchanger 25 Stop the cooling operation. Thereby, overcooling of the opening inner wall 17 is prevented.
[0021]
The decrease in the cooling capacity of the second heat exchanger 25 by the cooling controller 21 is continued until NO in step S23, that is, T2 ≧ Tth2.
In step S23, when the detected current temperature T2 is higher than the threshold value Tth2 (NO), in step S25, the cooling controller 21 increases the cooling capacity of the second heat exchanger 25, or the second heat The cooling operation of the exchanger 25 is started.
[0022]
The increase in the cooling capacity of the second heat exchanger 25 by the cooling controller 21 is continued until YES in step S23, that is, T2 <Tth2.
As described above, according to the present embodiment, the temperature of the opening inner wall 17 with which the subject may come into contact is detected regardless of the temperature of the cooling water as in the prior art, and based on this, the opening inner wall is further detected. Since 17 is directly cooled, the response time of the cooling with respect to the temperature rise is shortened, the conventional excessive cooling becomes unnecessary, and the running cost required for the cooling can be reduced. The gradient coil 5 can also be cooled to a minimum level so as not to exceed the allowable temperature of the gradient coil 5 and the conventional overcooling becomes unnecessary, reducing the running cost required for cooling. be able to.
(Second Embodiment)
FIG. 3 shows the configuration of the cooling device according to the second embodiment. In FIG. 3, the same parts as those in FIG. The host controller 35 is a control center of the entire MR system. Connected to the host controller 35 are a monitor 37 for displaying scanning (imaging) setting conditions, a setting guide, and the like, and a keyboard 39 and a mouse 41 for inputting instructions such as setting of scanning conditions and start / end of scanning. ing.
[0023]
Based on the temperature detected via the first temperature sensor 13, the cooling controller 21 has a gradient (time fluctuation) of the temperature rise of the gradient coil 5 that exceeds the cooling capacity of the first heat exchanger 23. Even if the heat exchanger 23 is operated with the maximum cooling capacity, it is determined whether it is impossible to suppress the temperature rise of the gradient coil 5, and based on the temperature detected via the second temperature sensor 15. The inclination (time fluctuation) of the temperature rise of the opening inner wall 17 exceeds the cooling capacity of the second heat exchanger 25, and the temperature of the opening inner wall 17 increases even if the second heat exchanger 25 is operated at the maximum cooling capacity. It is determined whether or not suppression is impossible, and when at least one of these determinations indicates that “temperature increase cannot be suppressed”, a scan pause signal is sent to the host controller 35. Output to. The scan pause signal is obtained until the temperature T1 at the gradient magnetic field coil 5 by the first temperature sensor 13 becomes lower than the threshold value Tth1, and the temperature T2 at the opening inner wall 17 by the second temperature sensor 15 becomes lower than the threshold value Tth2. , Continuously supplied from the cooling controller 21 to the host controller 35.
[0024]
While receiving the scan pause signal, the host controller 35 stops scanning and does not accept a scan start command from the keyboard 39 or the mouse 41 (interlock is applied). Further, the host controller 35 supplies a graphic signal of the message to the monitor 37 in order to display a message indicating that the scan is suspended on the monitor 37. Further, the host controller 35 displays a wait time until the scan can be restarted after the scan pause signal is stopped based on the cooling rate under the stop of the scan. Supply signal.
[0025]
Thus, according to the present embodiment, it is possible to appropriately interlock according to the state of temperature rise. In addition, it is possible to present to the operator that the scan is suspended and the waiting time.
(Third embodiment)
FIG. 4 shows the configuration of the cooling device according to the third embodiment. In FIG. 4, the same parts as those in FIG. In the first embodiment, two heat exchangers are installed, but in the third embodiment, the same operation and effect as the first embodiment are realized by one heat exchanger. is there.
[0026]
The heat exchanger 43 circulates the coolant between both the first cooling unit 9 and the second cooling unit 11 via the coolant tubes 31 and 33. An electromagnetic valve 45 is interposed in the coolant tube 33 of the second cooling unit 11. The solenoid valve 45 is not interposed in the coolant tube 31 of the first cooling unit 9. When the solenoid valve 45 is opened, the coolant tube 33 is in a conducting state, and the coolant is circulated between the heat exchanger 43 and the second cooling unit 11. When the solenoid valve 45 is closed, the cooling liquid tube 33 is in a non-conductive state, and the circulation of the cooling liquid between the heat exchanger 43 and the second cooling unit 11 is stopped.
[0027]
FIG. 5 shows control means for the heat exchanger 43 of the cooling controller 41 . It should be noted that the cooling stop and the cooling start are deleted in step S14 and step S15. That is, the cooling controller 41 adjusts the cooling capacity of the heat exchanger 43 while scanning is performed, but operates continuously without stopping the heat exchanger 43.
[0028]
In step S23, when the detected current temperature T2 is lower than the threshold value Tth2 (YES), in step S26, the cooling controller 41 closes the electromagnetic valve 45 and stops cooling the inner wall 17 of the opening. Thereby, overcooling of the opening inner wall 17 is prevented. Closing the electromagnetic valve 45 is continued until NO in step S23, that is, T2 ≧ Tth2.
[0029]
In step S23, when the detected current temperature T2 is higher than the threshold value Tth2 (NO), in step S27, the cooling controller 41 opens the electromagnetic valve 45 and cools the inner wall 17 of the opening. The opening of the electromagnetic valve 45 by the cooling controller 41 is continued until YES in step S23, that is, T2 <Tth2.
[0030]
As described above, according to the present embodiment, the same operational effects as those of the first embodiment can be achieved by one heat exchanger.
The present invention is not limited to the above-described embodiment, and can be implemented with various modifications.
[0031]
【The invention's effect】
According to the present invention described above, there is no need to foresee the time required for the heat generated in the coil is conducted to the opening in the wall of the MR magnet portion which may be touched by a subject as the heat source, the conventional Such an early and early excessive cooling in anticipation of this conduction time becomes unnecessary, and it is possible to realize a highly efficient cooling with a short response without causing discomfort to the subject.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a cooling apparatus for an MR magnet unit according to a first embodiment.
FIG. 2 is a flowchart showing a control procedure for the heat exchanger of the cooling controller of FIG. 1;
FIG. 3 is a configuration diagram of an MR magnet unit cooling device according to a second embodiment;
FIG. 4 is a configuration diagram of an MR magnet section cooling device according to a third embodiment;
FIG. 5 is a flowchart showing a control procedure for the heat exchanger of the cooling controller of FIG. 4;
[Explanation of symbols]
1 ... MR magnet part,
2 ... opening,
3 ... Static magnetic field magnet,
5. Gradient magnetic field coil,
7 ... RF coil,
9 ... 1st cooling part,
11 ... 2nd cooling part,
13 ... 1st temperature sensor,
15 ... second temperature sensor,
17 ... the inner wall of the opening,
20 ... cooling device body,
21 ... Cooling controller,
23. First heat exchanger,
25 ... second heat exchanger,
27 ... first cable,
29 ... second cable,
31 ... 1st cooling water tube,
33 ... Second cooling water tube.

Claims (11)

A static magnetic field magnet that generates a static magnetic field, a coil that generates a magnetic resonance signal from the subject, a cooling unit that is provided between the static magnetic field magnet and the coil, and that cools the coil is housed, and the subject is inserted An MR magnet part having an opening for
A detecting means for detecting the temperature of the MR magnet portion of the opening in the wall,
MR system based on the temperature of the opening in the wall, characterized by comprising a cooling controller for controlling the operation of the MR the cooling unit which is accommodated in the magnet unit. The cooling controller, MR system of claim 1, wherein the temperature of the opening wall and adjusting the cooling capacity of the cooling unit so as not to exceed a predetermined upper limit temperature. The detecting device, MR system of claim 1, wherein the detecting the temperature of the innermost surface of the opening in the wall. The detecting device, MR system of claim 2, wherein the detecting the temperature of the innermost surface of the opening in the wall.   5. The MR system according to claim 1, wherein the cooling unit is installed integrally with or adjacent to an RF coil housed in the MR magnet unit. 6. A static magnetic field magnet for generating a static magnetic field;
A gradient coil for generating a gradient magnetic field;
A first cooling unit provided between the static magnetic field magnet and the gradient magnetic field coil for cooling the gradient magnetic field coil;
An RF coil for transmitting RF pulses;
A second cooling unit that is provided between the gradient coil and the RF coil and cools the RF coil;
First detection means for detecting the temperature of the gradient coil;
The static magnetic field magnet, and the gradient coil, said RF coil, a second detecting means for detecting the temperature of the opening in the wall of the MR magnet portion for accommodating the first cooling unit and the second cooling section,
That on the basis of the temperature of the gradient coil to control the operation of the first cooling section comprises a cooling controller for controlling the operation of the second cooling unit based on the temperature of the opening in the wall MR system characterized by this. The cooling controller, MR system of claim 6, wherein the temperature of the opening in the wall to adjust the cooling capacity of the second cooling section so as not to exceed a predetermined upper limit temperature.   The MR system according to claim 6 or 7, wherein the cooling controller adjusts the cooling capacity of the first cooling unit so that the temperature of the gradient coil does not exceed a predetermined allowable temperature.   The first cooling unit and the second cooling unit share a common heat exchange for circulating a cooling station between the first cooling unit and the second cooling unit through a coolant tube. The MR system according to claim 6, further comprising a device.   The MR system according to claim 9, wherein the cooling tube includes a solenoid valve that can be freely opened and closed. The cooling controller, MR system of claim 10, wherein the opening and closing the electromagnetic valve based on the temperature of the surface of the opening in the wall.

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