JP2007038017A - Mri apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a defect which occurs when a rise in temperature cannot be curbed. <P>SOLUTION: An MRI apparatus comprises temperature sensors 13 and 15 for sensing temperature of an MR magnet section 1, a cooling section 9 and 11 for cooling the MR magnet section 1, and a host controller 35 for interlocking not to execute scanning to a test subject based on the temperature sensed by the temperature sensor 13 and 15. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an MRI apparatus that provides diagnostic information such as MRI (Magnetic Resonance Image) and frequency spectrum using a magnetic resonance phenomenon.

In the MR magnet part in the MR system, a static magnetic field magnet, a gradient magnetic field coil,
It is equipped with an RF coil. Among them, the heat source that generates the most heat is a gradient coil that is repeatedly supplied with very high current pulses.

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. In the conventional cooling device,
A temperature sensor is installed in a return tube from the cooling section to the heat exchanger, and the cooling capacity is adjusted by monitoring the temperature of the return coolant.

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.

Conventionally, the cooling capacity is adjusted regardless of the gradient of temperature rise.
JP-A-8-98829

Conventionally, since the cooling capacity is adjusted regardless of the temperature rise gradient, it is sometimes impossible to suppress the temperature rise.

Therefore, an object of the present invention is to solve a problem that occurs when it is impossible to suppress a temperature rise.

In order to achieve the above object, an MRI apparatus of the present invention scans a subject based on detection means for detecting a temperature related to an MR magnet part, a cooling part for cooling the MR magnet part, and the temperature. And control means for applying an interlock so as not to execute.

According to the present invention, it is possible to solve a problem that occurs when it is impossible to suppress a temperature rise.

  Embodiments of the MRI apparatus according to the present invention will be described below with reference to FIGS.

(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 In order toward 2, the static magnetic field magnet 3,
The gradient coil 5 and the RF coil 7 are accommodated. The dotted ellipse is X by the gradient coil 5.
This is a region where the magnetic field intensity changes linearly along each axis YZ, and imaging, that is, sampling of the magnetic resonance signal is possible in this region.

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. The first cooling unit 9 provided adjacent to the gradient magnetic field coil 5 or molded integrally with the gradient magnetic field coil 5, and the RF located at the innermost side of the opening 2 of the MR magnet unit 1
Second cooling unit 11 provided adjacent to coil 7 or molded integrally with RF coil 7
And have.

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 the first heat exchanger 23 and the first
The cooling unit 9 is circulated through the cooling water tube 31. The coolant is circulated between the second heat exchanger 25 and the second cooling unit 11 via the cooling water tube 33.

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 2 via the second cable 29.
1, the temperature of the opening inner wall 17 is detected. 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.

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.

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.

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 magnetic field 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.

In step S13, the temperature T1 of the gradient coil 5 detected by the first temperature sensor 13 takes into account the response time from the allowable temperature of the gradient coil 5 according to the heat capacity of the gradient coil 5 in the cooling controller 21. Threshold value Tth1 that is set slightly lower
Compared with

When the detected current temperature T1 is lower than the threshold value Tth1 (YES), step S1
4, the cooling controller 21 reduces the cooling capacity of the first heat exchanger 23 or stops the cooling operation of the first heat exchanger 23. 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.

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), step S15
The cooling controller 21 increases the cooling capacity of the first heat exchanger 23 or starts the cooling operation of the first heat exchanger 23. 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.

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, the second heat exchanger 2
The control system for 5 will be described. First, in step S21, the second temperature sensor 15
Is driven by the cooling controller 21. Thus, in step S22, the temperature T2 of the opening inner wall 17 that is closest to the subject and that may contact 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.

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 it can be uncomfortable.

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.

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.

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 inner wall 1 of the opening that may be in contact with the subject regardless of the temperature of the cooling water as in the prior art.
7 is detected, and based on this, the opening inner wall 17 is directly cooled. Therefore, the response time of the cooling to the temperature rise is shortened, and the conventional overcooling becomes unnecessary, The running cost required for cooling can be reduced. The gradient coil 5 can be cooled to a minimum level so as not to exceed the allowable temperature of the gradient coil 5.
Conventional overcooling becomes unnecessary, and the running cost required for cooling can be reduced.

Since the cooling capacity of the cooling unit is adjusted based on the temperature near the inner wall of the opening of the MR magnet unit,
There is no need to allow for the time required for the heat generated by the heat source to conduct to the innermost part, eliminating the need for early and early overcooling in anticipation of this conduction time, and high efficiency with short responsiveness Cooling at is realized.

(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 and setting guides, a keyboard 39 and a mouse 41 for inputting instructions such as setting of scanning conditions and start / end of scanning. ing.

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 in the gradient magnetic field coil 5 by the first temperature sensor 13 becomes lower than the threshold value Tth1 and the temperature T2 in 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.

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.

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.

The heat exchanger 43 includes the first cooling unit 9 and the second cooling unit 11 via the coolant tubes 31 and 33.
Circulate the coolant between both. The coolant tube 33 of the second cooling unit 11 has a solenoid valve 4.
5 is interposed. 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.

FIG. 5 shows a control procedure 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 continuously operates without stopping the heat exchanger 43.

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,
Cooling of the inner wall 17 of the opening is stopped. 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.

In step S23, when the detected current temperature T2 is higher than the threshold value Tth2 (N
O) 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.

Since the cooling capacity of the cooling part is adjusted based on the temperature near the inner wall of the opening of the MR magnet part, it is not necessary to allow for the time required for the heat generated in the heat source to be conducted to the innermost part. Such excessive cooling early in anticipation of this conduction time becomes unnecessary, and cooling with high efficiency is realized with short response.

As described above, according to the present embodiment, it is possible to achieve the same operational effects as those of the first embodiment with one heat exchanger. The present invention is not limited to the above-described embodiment, and can be implemented with various modifications.

The block diagram of the cooling device of the MR magnet part by Example 1 of this invention. The flowchart which shows the control procedure to the heat exchanger of the cooling controller of FIG. The block diagram of the cooling device of the MR magnet part by Example 2 of this invention. The block diagram of the cooling device of the MR magnet part by Example 3 of this invention. The flowchart which shows the control procedure to the heat exchanger of the cooling controller of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 MR magnet part 2 Opening part 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 2nd temperature sensor 17 Opening inner wall 20 Cooling device main body 21 Cooling controller 23 1st heat exchanger 25 2nd heat exchanger 27 1st cable 29 2nd cable 31 1st cooling water tube 33 2nd cooling water tube

Claims (10)

Detecting means for detecting a temperature related to the MR magnet part;
A cooling part for cooling the MR magnet part;
An MRI apparatus comprising: a control unit that interlocks the subject so as not to execute a scan based on the temperature. The detecting means is means for detecting the temperature of the gradient magnetic field coil housed in the MR magnet section;
And means for detecting the temperature of the opening wall of the MR magnet part,
The cooling unit has a first cooling unit that cools the gradient magnetic field coil, and a second cooling unit that cools the RF coil housed in the MR magnet unit,
The control means outputs a signal for interlocking based on at least one of the temperature of the gradient magnetic field coil or the temperature of the opening wall; and
The MRI apparatus according to claim 1, comprising: The control means includes a cooling controller that controls the first cooling unit based on the temperature of the gradient coil and controls the second cooling unit based on the temperature of the opening wall. The MRI apparatus according to claim 1 or 2, characterized by the above. The MRI apparatus according to claim 3, wherein the cooling controller does not accept the execution of the scan when it is determined that the increase in temperature exceeds the cooling capacity of the cooling unit. The MRI apparatus according to claim 3, wherein the cooling controller waits for the scan when it is determined that the increase in temperature exceeds the cooling capacity of the cooling unit. When the cooling controller determines that the increase in temperature exceeds the cooling capacity of at least one of the first cooling unit and the second cooling unit, the cooling controller does not accept the execution of the scan or waits. 5. The MRI apparatus according to claim 4, wherein the MRI apparatus is characterized. The said cooling controller has a means to display the stand-by message which does not accept execution of the said scan, or makes it wait when it judges that the raise of the said temperature exceeds the cooling capacity of the said cooling part. MRI equipment. When the cooling controller determines that the increase in temperature exceeds the cooling capacity of at least one of the first cooling unit and the second cooling unit, the cooling controller does not accept the execution of the scan or waits to wait 5. The MRI apparatus according to claim 4, further comprising a means for displaying. 5. The MRI apparatus according to claim 3, wherein the cooling controller has means for calculating a waiting time until execution reunion of the waiting scan. The MRI apparatus according to claim 9, wherein the cooling controller includes means for displaying the waiting time.

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