JPH01223946A - Top plate of bed for magnetic resonance imaging - Google Patents

Abstract

PURPOSE:To immediately detect the presence of the metal piece on an examinee when the examinee is arranged on the top plate of a bed, by internally mounting a transmitting high frequency coil for forming a high frequency magnetic field and/or a receiving high frequency coil for detecting the change of a high frequency magnetic field. CONSTITUTION:In the cross-sectional area of a top plate 2 in a short direction thereof, one coil 4a is arranged to the top plate 2 along the outer edge thereof. When a transmitting high frequency coil 4 is mounted in the top plate 2 and a receiving high frequency coil 6 is mounted in a high frequency opposed plate 3, said high frequency coils 4, 6 function as a metal detection mechanism forming a part of a metal detection circuit. When an examinee is arranged in a high frequency magnetic field and a metal piece is applied to the body of the examinee, marked variation is generated in the intensity of the high frequency magnetic field received by the receiving high frequency coil 6 and a metal piece detection signal is induced in the high frequency coil 5. By this method, after the examinee is arranged on the top plate 2, the presence of the metal piece on the examinee can be automatically detected.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is applied to magnetic resonance imaging (hereinafter referred to as MRI) equipment that uses magnetic resonance development to image a subject. The present invention relates to a bed top for MRI, and particularly to several layers of a bed top structure.

(Prior Art) As is well known, in IvlR1, each gradient magnetic field for encoding, thrilling, and Φgaima-deing and a magnetic field for high-frequency excitation are applied to a subject placed in a static t4i field. At the same time, the magnetic resonance signals obtained by this magnetic resonance phenomenon are collected and subjected to image reconstruction processing and us vector analysis processing, and these processing results are displayed on a CRT, etc. It is designed to be displayed on the screen.

When a subject is imaged using such an MRI device, if a metal piece is dragged or held on the body of the subject, magnetostriction occurs in the static Ql field, causing distortion in the decoy image.
This may cause the operator to misdiagnose the subject. Furthermore, if metal fragments are present in the body of the subject, the MRI transporting and imaging metal fragments act as bullets, which is extremely dangerous.

From this point of view, conventionally, when a subject is accommodated together with a bed top in a static magnetic field forming space of an MRI apparatus, it has been artificially checked to see if a metal piece is attached or held on the body of the subject.

(Problem to be solved by the invention) However, when confirming the presence or absence of metal fragments by artificially examining the body as in the past, even if there is a metal fragment on the subject's body, it may be mistakenly recognized that there is no metal j1. There was a risk that the decision would be made and the MRI machine would start taking pictures.

The present invention has been made in view of this problem, and its purpose is to be able to immediately detect the presence or absence of metal pieces on a subject when the subject is placed on the bed top. An object of the present invention is to provide a structured bed top plate for MRI.

[Configuration of the Invention (Means for Solving the Problems) In order to achieve the above object, the present invention
A bed top plate configured to be able to mount at least a part of the subject in the static VTI field forming space of The main feature is that it has a built-in high-frequency coil for reception to detect changes.

(Function) With the MRI bed board according to the present invention, when a subject is placed on the large bed board F, a high frequency magnetic field is transmitted and received by a high frequency coil before the start of magnetic resonance imaging. With this, it is possible to detect the presence or absence of metal pieces on a subject.

(Embodiment) FIG. 1 is a block diagram schematically showing an embodiment of a bed top plate to which the present invention is applied.

The bed top plate of this embodiment includes a top plate 2 that is moved along a top plate movement frame 1, and a high-frequency opposing plate 3 that is disposed opposite to this top plate 2 with a subject interposed therebetween. There is.

The top plate 2 is formed by molding a non-metallic material such as a wooden board or an acrylic plate 1 synthetic resin so as to be able to mount the test object thereon.
In order to form a high frequency magnetic field in the space above the top plate 2, a high frequency coil 4 is built in as shown in FIG. 2, and a coil lead wire 5 is arranged from this high frequency coil 4 to one end of the top plate 2. It is said that it can be connected to a magnetic detection circuit to be described later.

When the high frequency coil 4 etc. is built into the top plate 2,
It is preferable that the high-frequency coil 2 and the like be sandwiched between two plate materials and pressed against each other from above and below for molding.

In addition, in one embodiment of the present invention, as the high-frequency coil 4 built into the top plate 2, one coil is arranged along the outer edge of the top plate 2 in a cross section in the short direction of the top plate 2, as shown in FIG. 4a is arranged, and two coils 4b and 4c are arranged inside this coil 4a, and these coils 4a to 4C are arranged along the longitudinal direction of the top plate 2. Coil 4 was used. In this case, the strength of the high frequency magnetic field formed in the space above the top plate 2 by the high frequency coil 4 can be changed as appropriate.

In order to detect the transformer of the high frequency magnetic field formed in the space above the large plate 2 by the high frequency coil 4, the high frequency opposing plate 3 is equipped with a high frequency coil consisting of two coils 6a and 6b as shown in FIG. 6 built-in, and is shaped like a saddle so that it can surround the subject.

In this way, if the top plate 2 has a built-in high-frequency coil 4 for transmitting, and the high-frequency opposing plate 3 has a high-frequency receiving coil 6 built-in, these high-frequency coils 4 and 6 can be used in the metal detection circuit. It functions as a total bending detection mechanism.

That is, in this embodiment, as shown in FIG.
DC power source 8 according to the control sequence of controller 7. The high frequency oscillator 9 and the signal output device 10 are driven and controlled, and the high frequency oscillator 9. Signal output device 10. The circuit configuration is such that drive current is supplied to the waveform shaper 11 and the high frequency amplifier 12, and a metal detection circuit is employed in which the high frequency coils 4 and 6 function as a metal detection structure.

Therefore, the high frequency oscillator 9 is operated in accordance with the control sequence of the controller 7, and the output of this oscillation operation is applied to the high frequency coil 4 built in the top plate 2 of FIG. Therefore, a high frequency magnetic field is formed in the space above the top plate 2 in FIG. 1 by the high frequency coil 4.

If the subject is placed in the high-frequency magnetic field generated by the high-frequency coil 4, if a metal piece is attached or held on the body of the subject, the high-frequency opposing plate 3 shown in FIG.
Since there is a noticeable fluctuation in the strength of the high-frequency magnetic field received by the high-frequency coil 6 built into the high-frequency coil 5,
A metal detection signal is induced.

The induced metal piece detection signal is amplified by a high frequency amplifier 11, then shaped into a waveform by a waveform shaper 10, and outputted as a signal from a signal output device 9 to a notification means (not shown) such as a buzzer or a meter. Therefore, this notification means will issue an abnormality notification when the signal A indicates that a metal piece has been detected.

Therefore, according to one embodiment of the present invention, after the subject is placed on the top plate 2'', it is possible to automatically detect the presence or absence of metal pieces on the subject.

Note that when performing MRI imaging, one of the high-frequency coil 4 built into the top plate 2 and the high-frequency coil 6 built into the high-frequency opposing plate 3 is used for generating the high-frequency magnetic field for excitation, and the other one is used for generating the high-frequency magnetic field for excitation. can be used for receiving magnetic resonance signals (MR signals).

Furthermore, by removing the high-frequency opposing plate 3 from the top plate 2, the high-frequency coil 4 built into the top plate 2 can be used both for generating the high-frequency magnetic field for excitation and for receiving MR and other signals.

An MRI apparatus that uses the high-frequency coil 4 built into the top plate 2 for both the generation of a high-frequency magnetic field for excitation and the reception of MR and other signals has, for example, a schematic configuration as shown in FIG. Become.

At the groove bottom of the MRI apparatus as shown in FIG. 6, the subject is housed in a static magnetic field space created by the main magnet 13 together with the top plate 2 shown in FIG. Since the gradient magnetic field coil 14 is arranged in the static magnetic field forming space, the gradient magnetic field coil 14 generates a static magnetic field! Gradient magnetic fields of X, Y, and Z along three orthogonal directions are applied to the subject under one field.

Further, a high frequency magnetic field for excitation is applied by a high frequency coil 4 built into the top plate 2.

By applying these, a magnetic resonance phenomenon is generated in a specific part of the subject, and MR and other signals generated by this magnetic resonance signal are inputted via the high-frequency coil 4 to the control computer 15 to obtain biological diagnosis information of the subject. With,
The content of the biological diagnosis information can be displayed as an image on the monitor 16.

When performing such MRII imaging, as described above, if the presence or absence of metal fragments is detected on the subject and the object is kept free of metal fragments, MRII imaging can be performed satisfactorily.

[Effects of the Invention] As explained above, the Q table top plate for MR1 to which the present invention is applied is capable of transmitting high-frequency waves for forming a high-frequency field and/or receiving high-frequency waves for detecting changes in a high-frequency magnetic field. It has a built-in coil. Therefore, when a subject is placed on the bed top, by transmitting and receiving a high-frequency magnetic field using a high-frequency coil before starting MRI scanning, it is possible to detect the presence or absence of metal pieces on the subject.

In addition, after detecting the presence or absence of metal pieces on the subject, a high-frequency magnetic field for excitation can be applied and/or an MR signal can be received using a high-frequency coil built into the top of the bed.
The handling of shadows is significantly improved compared to the conventional method.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an outline of an embodiment of the position of the bed top plate to which the present invention is applied, Fig. 2 is an example diagram of the top plate structure, Fig. 3 is a detailed explanatory diagram of the top plate structure, and Fig. 4 The figure is a detailed explanatory diagram of the high frequency opposing plate, Figure 5 is a circuit diagram showing an example of a metal detection circuit, and Figure 6 is a circuit diagram showing an example of a metal detection circuit.
The figure is a block diagram schematically showing the entire MRI apparatus. 1... Top plate moving frame 2... Top plate 3... High frequency opposing plate 4... High frequency coil 5... Coil lead wire 6... High frequency coil 7... Controller 8... DC power supply 9... High frequency oscillator 10... Output signal device 11... Waveform shaper 12... High frequency amplifier

Claims (3)

[Claims] (1) A bed top plate configured to be able to mount at least a part of the subject in order to place the subject in a static magnetic field forming space of a magnetic resonance imaging apparatus, which is equipped with a transmitter and a transmitter for forming a high-frequency magnetic field. A bed top plate for magnetic resonance imaging, characterized in that a high-frequency coil is built-in for reception to detect changes in a high-frequency magnetic field. (2) The bed top plate is equipped with a high-frequency opposing plate containing another high-frequency coil capable of transmitting and receiving data to and from the high-frequency coil built into the bed top plate, and the high-frequency opposing plate is provided with the subject interposed therebetween. The bed top plate for magnetic resonance imaging according to claim 1, characterized in that the bed top plate for magnetic resonance imaging is configured to be arranged facing each other. (3) The bed top plate is configured to be able to switch a high frequency coil built into the bed top plate and/or a high frequency coil built into the high frequency opposing plate into a high frequency coil of a high frequency magnetic field system for excitation during magnetic resonance imaging. The bed top plate for magnetic resonance imaging according to claim 2, characterized in that: