JPS63220858A - Magnetic resonance imaging apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to magnetic resonance (MR)
esonance) phenomenon to determine the density distribution of specific nuclear spins in specific parts of the subject (living body).
For example, computed tomography (CT)
C T 'a by dton+oaraphy) method
The present invention relates to a magnetic resonance imaging apparatus that generates information such as (computed toll ogral), and particularly relates to a magnetic resonance imaging apparatus that can prevent mutual influence between a subject or an operator and a magnetic field.

(Prior Art) For example, a magnetic resonance imaging apparatus for medical diagnosis generally includes a bed for placing a patient and a patient placed on the bed, which is introduced into the device and placed in a uniform static state. A main body that generates an MR phenomenon by applying a magnetic field, a gradient magnetic field, and an excitation rotating magnetic field and detects a signal based on the induced MR phenomenon; a power source for generating the magnetic field; and a power source that controls the bed and the power source. and a computer system that processes the detection signal. The bed and the main body are placed inside a far shadow room that is magnetically shielded.
Other elements are generally located outdoors.

With the above configuration, a superimposed magnetic field is formed in the main body by adding a gradient magnetic field from a gradient magnetic field generating coil to a uniform static magnetic field from the -m static magnetic field generator, and this superimposed magnetic field f! i
Test subjects are placed all over the place.

A probe coil is placed above the subject, and this coil applies an excitation rotating magnetic field to cause the MR phenomenon in the subject, and the induced MR multiplied signal is detected by the same coil and processed by an image processing device, etc. Information such as tomographic images is obtained through image reconstruction processing, and images are displayed.

In such a magnetic resonance imaging apparatus, the uniform static magnetic field is made to have a high magnetic field in order to improve image quality, and the gradient magnetic field is made to have a high magnetic field and various forms in order to realize various imaging modes. In addition, as uniform static magnetic field generators, those using conventional electromagnetic coils such as normal conducting coils and superconducting coils, and those using permanent magnets have also appeared.

In such a situation, the mutual influence between the magnetic field generated by the magnetic resonance imaging apparatus and the subject or operator, which has been a problem in the past, becomes increasingly problematic.

First, the influence of the magnetic field on the subject and the operator will be explained. In other words, when a subject or operator who has metal equipment or an artificial device using metal materials in the body approaches a magnetic field source, the magnetic field acts on the metal equipment or artificial device inside the body, causing the metal Equipment or equipment is dangerous because it may move the artificial device itself outside or within the body.Also, it may inadvertently attract the patient or operator holding it to the source of the magnetic field. Furthermore, eddy currents are generated in metal equipment or artificial devices inside the body, generating high heat, which is dangerous as there is a risk of burns.

Next, the influence of the subject and the operator on the magnetic field will be explained. That is, when a subject or an operator who has magnetic metal equipment or an artificial device using a magnetic metal material in the body approaches the magnetic field forming space, especially near the excitation site, the magnetic field forming space, especially near the excitation site, approaches. This is a problem because it disturbs the magnetic field, greatly affecting signal detection accuracy and ultimately diagnostic information.

The above-mentioned problem arises when a person with an artificial device made of metal inside their body is brought to the hospital as an emergency patient and an emergency diagnosis is performed. If it is not possible to ask the patient, it is highly likely that this will occur.

(Problems to be solved by the invention) As described above, in the conventional technology, it is difficult to
A subject or an operator holding an electric or highly magnetic object may approach a magnetic field area, causing a mutual influence between the highly conductive or highly magnetic object and the magnetic field, which poses a problem.

Therefore, it is an object of the present invention to prevent subjects and operators carrying highly conductive materials such as magnetic metals or highly magnetic materials from approaching the magnetic field region, or even if they do, it will adversely affect the diagnosis. An object of the present invention is to provide a magnetic resonance imaging apparatus as described above.

(Means for Solving the Problems) The present invention is characterized by taking the following measures in order to solve the above problems and achieve the object. That is, in the magnetic resonance imaging apparatus according to the present invention, the detection means for detecting at least one of the highly conductive material and the highly magnetic material is configured such that the magnetic field and at least one of the highly conductive material and the highly magnetic material mutually influence each other. The detection signal from the detection means is used as information for one of the control, signal processing, and patient diagnosis.

(Function) According to such a configuration, the detection means can detect a subject or an operator holding a highly conductive object such as a magnetic metal or a highly magnetic object in the mutual influence area, and use this detection signal to It is possible to perform operation stop operations, perform signal processing operations such as influence correction, and obtain information indicating that a highly conductive material such as a magnetic metal or a highly magnetic material is present as a patient diagnosis.

(Example) An example of a magnetic resonance imaging apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of the same embodiment, FIG. 2 is a front view of the main body in the same embodiment, and FIG. 3 is a circuit diagram showing the configuration of the metal detector in the same embodiment.

In FIG. 1, in the magnetic resonance imaging placement of this embodiment, a bed 1 on which a top plate 1a on which a subject P is placed is slidable is placed in an imaging room R equipped with magnetic shielding, radio wave shielding, etc. It is installed. In addition, the uniform static magnetic field generating coil 2a
, a gradient magnetic field generating coil 2b, and a coil 2C for generating an excitation rotating magnetic field and for signal detection. A main body 2 is installed in the imaging room R, which generates a magnetic resonance phenomenon by applying a uniform static magnetic field, a gradient magnetic field, and an excitation rotating magnetic field, and detects a signal based on the induced magnetic resonance phenomenon.

Further, a magnetic field power supply 3 for generating the magnetic field, and a computer 4 for controlling the bed 1 and the magnetic field power supply 3 and processing the detection signal. and its II and III tables 5 are installed outside the imaging room R.

Further, a detection unit 6 is provided at the entrance/exit of the subject on the front side of the main body 2, and this detection unit 6 is equipped with two metal detectors 7.8 and two optical sensors 9 and 10. Furthermore, a metal detector 11 is installed at the installation site of the top plate 1a of the bed 1.
is provided.

Further, a metal detector 12 is installed in 1iRD of the shooting sky R.

These metal detectors 7, 8, 11, 12 and optical sensors 9
(9a, 9b), 10 (10a, 10b) are operated by a signal processor 13, and the signal processor 13 sends a message to the computer 4 when a metal detection signal is obtained from the metal detectors 7, 8, 11, 12. It is designed to give a signal. In response to the input of the gold 1 detection signal, the computer 4 issues a metal detection notification using light or sound, issues a command to stop the magnetic field power supply, and generates recorded information regarding the presence of metal.

FIG. 2 shows the configuration of the detection unit 6, in which metal detectors 7, 8 and optical sensors 9, 10 are arranged in a cross pattern.

Here, the light transmitters 9a, 10a and the light receivers 9b, 10b of the optical sensors 9, 10 are arranged so that their lights are orthogonal to each other, and the light transmitter 9a.

The subject P is detected by light reception and non-reception from the light receivers 10a to the light receivers 9b and 10b, and a detection signal is output. Here, in the optical sensors 9 and 10, the light transmitters 9a and 10a and the light receivers 9b and 10b are arranged so that the light beams are perpendicular to each other. can be reliably detected.

FIG. 3 shows the configuration of the metal detector 7.8.11.12, which has a transmitting coil 21 and two receiving coils 22 (22a, 22b) differentially coupled. The coil 22 is an MR that is assumed to be installed in advance.
This is corrected for the generated magnetic field. A high-frequency signal is supplied from the high-frequency oscillator 23 to the transmitting coil 21 to generate high-frequency magnetic lines of force, and if gold fiM exists between the transmitting coil 21 and the receiving coil 22, it changes the magnetic flux due to the magnetic lines of force. A signal is obtained from the receiving coil 22. This signal is amplified by a high frequency amplifier 24, and reaches a signal output circuit 26 via a waveform shaper 25, where the presence of the metal M is output as a pulse signal. Also, a high frequency oscillator 23° high frequency amplifier 24. Waveform shaper 2
5. The signal output device 26 is configured to receive power supply from a DC power source 27. Here, in the metal detector 7.8 shown in FIG. 2, its two transmitting coils and two receiving coils are arranged so as to be orthogonal to each other. Note that the metal detector 7.8 of the detection unit 6 operates while the switch 23a of the high frequency oscillator 23 is turned on by the signal output from the optical sensor 9.10.

Next, the operation of this embodiment configured as described above will be explained.

■ If you consider that a person who has an artificial device made of metal installed inside his or her body is brought to the hospital as an emergency patient (Subject P) and an emergency diagnosis is performed, it is important to consider that the person who has an artificial device made of metal installed inside his or her body is in an emergency situation and is unconscious. It may not be possible to ask the patient about the existence of

Even in this case, according to this embodiment, the presence or absence of metal on the subject P can be automatically detected at the entrance of the photography room R and the entrance of the main body of the bed 19, and the metal detection alarm can be sent by light or sound. It is possible to issue a command to stop power supply in the 11th field, and to generate recorded information on the presence of metal. Therefore, the shadow W/(suction, burn) of the magnetic field on the subject P (metal) does not occur, and the shadow It(1) of the subject P (metal) on the magnetic field does not occur.
1 field disturbance) can also be prevented.

■ According to this embodiment, the detection unit 6 is provided at the entrance/exit of the subject P of the main body 2, and the metal detector 7.8 is operated only when the presence of the subject P is confirmed using light. Therefore, when subject P is not present, metal detector 7.
8 does not operate and does not disturb the uniform static magnetic field that is continuously generated.

Furthermore, although the detection unit 6 includes metal, it is installed at the entrance/exit of the main body 2 for the subject, which is away from the excitation space (the space where the uniform static magnetic field, gradient magnetic field, and excitation rotating magnetic field act). , due to its existence, the disturbance of the magnetic field in the excitation space is extremely small and causes no problem.

(2) According to this embodiment, the area where the magnetic field and the metal mutually influence each other is the body 2 of the bed 19. ! II Shadow Room R Door RD
Since metal detectors 7.8 and 11.12 are provided at various locations, the detection order can be set within the signal processor 13 according to the detection area or detection level (corresponding to the size of the metal). Accordingly, various degrees of operational control such as metal detection alarm, magnetic field demagnetization, and system shutdown can be performed.

The present invention has other embodiments as follows. That is, in the above embodiment, the area where the magnetic field and the metal mutually influence each other is the body 2 of the bed 10. Metal detectors 7.8, 11.12 are installed at various locations in jlRD (7) in the photography room R, and depending on the detection area or detection level (corresponding to the size of the metal), 2 or in one or two of the IIRDs in the photographing room R.

Further, metals are generally good electrical conductors, but aluminum and the like are non-magnetic materials. Therefore, if a means for detecting a highly magnetic substance such as aluminum is provided in a region where the highly magnetic substance and the magnetic field interact, and the detection signal is used for operation IIJill, etc., it is possible to detect the interaction between the highly magnetic substance and the magnetic field. mutual influence can be prevented.

Note that although the above embodiment describes detecting metal, etc. of the IP to be tested, metals, etc., of all persons, including the operator, who approach the magnetic field forming area are detected. .

The invention can be modified in various ways without departing from the gist of the invention.

[Effects of the Invention] As described above, in the present invention, the detection means for detecting at least one of the good conductivity material and the highly magnetic material is configured such that the magnetic field and at least one of the good conductivity material and the highly magnetic material are mutually connected. Since it is installed in the area of mutual influence, the detection means can detect a subject or operator holding a highly conductive object such as a magnetic metal or a highly magnetic object in the area of mutual influence, and this detection signal can be used to control operation. It is possible to perform a stop operation, perform signal processing operations such as influence correction, and obtain information indicating that the patient has a good conductive material such as a metal or a magnetic material as a patient diagnosis.
This prevents subjects and operators carrying highly conductive materials such as magnetic metals or highly magnetic materials from approaching the magnetic field area, or prevents them from adversely affecting diagnosis even if they do. An imaging device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the magnetic resonance imaging apparatus according to the present invention, FIG. 2 is a front view of the main body of the same embodiment, and FIG. 3 is a diagram showing the configuration of metal detection values in the same embodiment. FIG. 1... Bed, 2... Main body, 3... Magnetic field power supply, 4
...Control console, 5.Computer, 6.Detection unit, 7.8.11.12.Metal detector, 9.1
0... Optical sensor, 13... Signal processor.

Claims (1)

[Claims] A bed for placing a patient on the bed and a patient placed on the bed are introduced into the bed, and a uniform static magnetic field, a gradient magnetic field, and an excitation rotating magnetic field are applied to the patient to cause a magnetic resonance phenomenon. Magnetic resonance comprising a main body that detects a signal based on an induced magnetic resonance phenomenon, a power source for generating the magnetic field, and a computer system that controls the bed and the power source and processes the detection signal. In the imaging apparatus, a detecting means for detecting at least one of a good conductor and a highly magnetic substance is provided in a region where the magnetic field and at least one of the good conductor and the highly magnetic substance interact with each other, and the detecting means detects at least one of the good conductor and the highly magnetic substance. A magnetic resonance imaging apparatus characterized in that a detection signal from the magnetic resonance imaging apparatus is used as information for at least one of the control, the signal processing, and the patient diagnosis.