JP2001008917A - Magnetic resonance imaging instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the burden of subject and improve imaging efficiency by sequentially moving vertically and horizontally based on the set feed volume that is calculated, based on the position data of light localizer, the distance from the pointing position to the magnetic filed center, vertical and horizontal directions, as a set feed volume. SOLUTION: A marker line 82c, which is longitudinal direction from a light localizer 80A to a bed 71, and a marker line 82b, which crosses at right angles to longitudinal direction, are projected with forming a intersection 81. Marker lines 82c are projected from light localizer 79A, 79B to horizontal direction with same height. Adjusting light localizer 79A, 79B, 80A to the photographing part, the values of resistance, which are detected with the potentiometers of light localizer 79A, 79B and 80A, are converted to analog voltage value or digital data with interface circuit. Then recognizing the data, calculating the distance to the magnetic field center, and deciding the set feed volume, the driving circuit is driven to move a top board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of performing efficient positioning without placing a burden on a subject when sending a tabletop into a gantry, and moving a desired imaging region to the center of a magnetic field easily and accurately. The present invention relates to a magnetic resonance imaging apparatus (hereinafter, referred to as an MRI apparatus) capable of performing such operations.

[0002]

2. Description of the Related Art An MRI apparatus has a gantry portion including a static magnetic field generator, a gradient magnetic field generator, a high frequency generator (RF).
Irradiation device) and a high-frequency receiving coil.

FIG. 7 is a view showing the gantry portion, and the static magnetic field generating device is, as shown in FIG. 7, a disk-shaped device opposed to a measurement space 50 into which a subject (not shown) is inserted. A pair of permanent magnets 52a, 52b having different polarities are arranged on the back side of the pole pieces 51a, 51b in a particularly close contact with the pole pieces 51a, 51b, and the pair of permanent magnets 52a, 52b are held and fixed. Yoke plates 53a, 53b are provided, and
3b is provided with two yoke bars 54a and 54b for connecting the yoke plates 53a and 53b to each other and maintaining a certain distance between the yoke plates 53a and 53b. In this case, the two yoke bars 54a and 54b can be sent to the measurement space 50 without being hindered by the yoke bars 54a and 54b in the device arranged on the rear side of the gantry 13.
Further, the opening 110 can be set large on the front side of the gantry 13. If the gradient magnetic field generator (not shown) and the RF irradiators 55a and 55b are flat,
The opening 110 is not closed and the distance between the RF irradiation devices 55a and 55b on the measurement space 50 side becomes the opening height (the height dimension of the measurement space 50).

[0004] As shown in FIG. 9, a patient table 71 for sending a subject to the center of a magnetic field in the gantry 13 includes:
A vertical movement which is a movement in the subject body axial direction (vertical direction) 72, a horizontal movement which is a movement 73 in a direction (lateral direction) orthogonal to the body axis direction 72 outside the gantry 13, and a vertical movement which is a movement in the vertical direction 74. It has a top plate movement function with movement. In this case, in the vertical movement, only the top 75 on which the subject lies is sent into the gantry 13, and the horizontal movement and the vertical movement move together with the top support 76. Each moving operation can be mainly performed by the operation panel 56 arranged on the gantry, and the top plate or the like is moved by pressing a button in each moving direction on the operation panel, and stopped when the button is released. It is done by moving.

The subject is placed on the top plate 75 when the top plate 75 is at the lower limit of the vertical movement in principle, and a roller (not shown) on the back surface of the top plate 75 is mounted on the RF irradiation device 55a below the gantry opening 110. After raising it to a height just touching the gantry 13
It is sent in with the top board 75. At this time, the light localizers 80a and 80b shown in FIG. 10 disposed in the light localizer mounting position 80 are instructed (illuminated).
By moving the measurement part of the subject vertically or horizontally to the position 81 (the intersection of the lines) determined by the lines 82a and 82b at one position, the top plate 75 on which the subject is placed or on the top plate By moving the subject (positioning operation) and vertically moving a certain distance therefrom, the set sending function that reaches the center of the magnetic field allows the subject to be sent to the center of the magnetic field.

The set feed function automatically moves the light localizers 82a and 82b from a fixed position 81 shown by the light localizers 82a and 82b to the center of the magnetic field by pressing an operation button (set feed button 99a) on the operation panel 56. However, it is necessary to operate the patient after moving the patient, including fine adjustment, so that the moving distance is constant in one direction only and is fixed, and the position 81 determined at one location matches the desired measurement portion. Was. This alignment is performed by a manual operation button 99b also on the operation panel. FIG. 8 is a functional block diagram thereof. First, a vertical movement and a horizontal movement are performed with the manual operation buttons 99b on the operation panels 56a and 56b, and the measurement site of the subject is adjusted to the fixed position 81. Then, when the set sending button 99a is pressed, a fixed set feeding is performed. Only the vertical movement drive circuit 97a is instructed to operate by the amount, and the vertical movement drive motor 98a is operated so that the top board 75 on which the subject is placed is placed.
Is sent to the center of the magnetic field. This set feed function is regarded as vertical movement, and horizontal movement is operated only by the manual operation button 99b.

[0007]

In the above prior art, sufficient consideration has not been given to the pain to be given to the subject (patient) in the positioning operation accompanying the set feeding operation. The positioning operation is a fixed position 81 determined by the light localizer.
In addition, moving the imaging region of the subject by moving the subject vertically or horizontally or finely by moving the subject on the tabletop is a painful operation for an unhealthy patient. It is easy to send the imaging part to the center of the magnetic field by the set feed operation and shoot at the place with the best magnetic field uniformity,
There is a great advantage that it is possible to obtain good images without image folding, distortion and S / N deterioration due to non-uniform magnetic field.However, when multiple imaging sites are used, several times the same subject is set. A feed operation is required, and a positioning operation is performed a plurality of times in accordance with this.In addition, since the light localizer is located only in front of the gantry, the top plate on which the subject is placed is at the deepest position. A very long return movement must be performed, which places even more distress on the patient. In addition, since the operation is frequently performed and the moving operation is performed several times, the throughput is reduced and the photographing efficiency is reduced.

An object of the present invention is to provide an MRI apparatus capable of reducing the burden on the subject, improving the imaging efficiency and improving the image quality, and eliminating the inconvenience of the imaging technician.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a gantry having a static magnetic field and a gradient magnetic field, and a gantry having a large opening in the front, and a method of irradiating an object with electromagnetic waves, A high-frequency coil for detecting a magnetic resonance signal from the, the image reconstruction means for obtaining an image representing the physical properties of the subject based on the signal detected by the high-frequency coil,
A vertical movement in the axial direction of the subject body for feeding the top plate on which the subject lies down to the opening or retracting from the feeding position to the outside of the opening, a horizontal movement perpendicular to the vertical movement direction, and the opening A magnetic resonance imaging apparatus comprising: a top table moving means for moving the top plate vertically up and down outside, and a patient table having a set feed function of sending an arbitrary measurement portion of the subject to the center of the static magnetic field. A light localizer that indicates an imaging region and has a position detection function, and a means for calculating a distance from the indicated position to the center of the magnetic field in both the vertical and horizontal directions based on position data of the light localizer as a set feed amount, and This is achieved by providing a means for sequentially performing vertical and horizontal movements based on the set feed amount.

[0010] Further, a gantry provided with a static magnetic field and a gradient magnetic field generating means and having a large opening in the front, and a high-frequency coil for irradiating the subject with electromagnetic waves or detecting a magnetic resonance signal from the subject. And image reconstruction means for producing an image representing the physical properties of the subject based on the signal detected by the high-frequency coil, and sending the top plate on which the subject lies to the opening or from the sending position to the opening. Longitudinal movement in the direction of the subject's body to be retracted outside the opening,
A set-feeding function having a table moving means for performing horizontal movement in the horizontal direction perpendicular to the vertical movement direction and vertical movement of the table outside the opening, and for sending an arbitrary measurement portion of the subject to the center of the static magnetic field; In a magnetic resonance imaging apparatus comprising a patient table having: a light localizer that points to an imaging region and has a position detection function, and a distance from the indicated position to the center of the magnetic field based on the position data of the light localizer. A means for calculating the set feed amount in both the vertical and horizontal directions is provided, and a means for sequentially performing vertical and horizontal movement based on the set feed amount is provided, and the light localizer is provided on both the front surface and the rear surface of the gantry. The effect of the present invention can be further enhanced by adopting a configuration that can be set and fed from either the front or rear surface. Can.

As described above, a light localizer that indicates a portion to be imaged and has a position detecting function, and the distance from the indicated position to the center of the magnetic field is calculated in both the vertical and horizontal directions based on the position data of the light localizer. By setting the amount, it is possible to perform positioning without moving the top plate on which the subject is placed or the subject itself even once, thereby reducing the burden on the subject and improving the imaging efficiency. By providing the light localizer, it is possible to easily move to the center of the magnetic field from either direction, and it is possible to greatly improve the imaging efficiency, reduce the burden on the imaging technician, improve the image quality, and greatly reduce the burden on the subject.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 6 are views for explaining an embodiment of an MRI according to the present invention.

FIG. 1 shows a gantry 13 and a bed 71 of an MRI apparatus.
2 is a rear perspective view of the gantry 13. FIG. In FIG. 1, the gantry 13 includes an upper magnet section 14 and a lower magnet section 15 provided to face each other up and down, and support sections 16a and 16b for supporting the magnet sections 14 and 15 so as to face each other. I have. Light localizer 80A for upper magnet section 14
Is provided at the lower front part of the magnet section where the bed 71 is located. From the light localizer 80A, a marker line 82c in the longitudinal direction of the bed 71 and a marker line 82b in a direction orthogonal to the longitudinal direction are provided by the light localizer 80a.
By turning on the power supply, two marker lines are projected downwardly forming an intersection 81. Note that the marker lines 82b are the upper and lower magnet portions 14, 15 of the gantry 13.
It corresponds to the center position when the uniform magnetic field region formed in the space between them is viewed in the vertical direction.

On the other hand, the column portions 16a and 16b are provided with light localizers 79A and 79B. When the power of these light localizers 79A and 79B is turned on, the marker lines 82c are projected at the same height in the horizontal direction. It has become so. The height position of the marker line 82c is the gantry 13.
This corresponds to the center position of the uniform magnetic field region formed in the space between the upper and lower magnet portions 14, 15 when viewed in the horizontal direction.

FIG. 1 shows the above three light localizers 7.
9A, 79B, and 80A are simultaneously turned on. As described above, when the three light localizers are simultaneously turned on and the subject is lying on the top of the bed 71,
The marker lines 82b and 82c are projected crosswise on the upper surface of the subject, and the marker lines 82b and 82c are projected crosswise on the side surface of the subject.

FIG. 3 is a configuration diagram of the light localizer 80A. The line 82b moves in the vertical direction 102b when the vertical light localizer 80a operates in the rotation direction 102a about the rotation axis 92d, and the moving amount As the light localizer rotates, a roller (cylindrical gear) 92b moves on a geared plate (rack gear) 92c and is detected as a resistance value of a vertical movement amount detecting potentiometer 92a.

FIG. 4 is a block diagram of the light localizer 80A. The lateral light localizer 80b moves in the lateral movement direction 101a together with the lateral movement amount detecting potentiometer 91a, and the line 82a moves in the lateral direction 101b. When the (mold gear) 91b moves on the geared plate (rack gear) 91c, the potentiometer 91a can detect the amount of movement as a resistance value. Also, rack gear
91c may be an arc type like 92c.

FIG. 5 shows a height detecting light localizer 79A,
In the configuration diagram of 79B, the height detecting light localizer 80c moves in the height direction 103a together with the position detecting potentiometer 93a to move the line 82c in the height direction 103b, and the roller (cylindrical gear) 93b has a geared plate ( By moving on the rack gear 93c, the potentiometer 93a can detect the amount of movement as a resistance value. Also, rack gear
93c may be an arc type like 92c.

Since the vertical movement direction 102b and the horizontal movement direction 101b are completely orthogonal to each other, the vertical movement line 82b does not move at all in the longitudinal direction of the bed 71 when moving in the horizontal movement direction. Similarly, during the vertical movement, the horizontal movement line 82a does not move at all in the longitudinal direction of the bed 71. Light localizers 79 for height detection are arranged at two places 79 on the left and right sides of the gantry, and both draw exactly the same bright line without displacement.

FIG. 6 is a functional block diagram of the position detecting mechanism. The imaging technician places the subject on the top plate and moves the subject up and down to the highest imaging position in the height direction. Therefore, the operation panel 56
The light localizer is adjusted to the part to be imaged by the positioning button 99d arranged in the camera. At this time, the positioning button has a vertical and horizontal height, and each potentiometer is provided by a small motor 84 (not shown) driven by pressing the button. The write localizer operates in each direction.

Since the vertical positioning line 82b has a large error due to obliquely crossing the subject as it moves away from the gantry, the height detection light is set after the positioning point 81 of the vertical and horizontal positioning line is adjusted to the desired imaging region. The localizer 79 adjusts the position to the highest position of the desired imaging region, thereby correcting the distance error so that the positioning point 81 is sent to the center of the magnetic field. Instead of this error correction, the set feed distance can be obtained by an arithmetic circuit such as a CPU using the intersection of the marker lines 82b and 82c as a positioning point.

The resistance value detected by each of the potentiometers 91a, 92a, 93a is converted into a specific value, for example, an analog voltage value or digital data by the interface circuit 94. These data are recognized, and the distance to the center of the magnetic field is calculated and set. The signal is sent to a circuit (CPU or the like) 95 for determining the feed amount. The determined set feed amount is a set feed setting circuit (counter circuit, etc.) 96a, which is directly connected to each drive circuit for vertical and horizontal movement.
Operation panel 5 set in 96b and placed in the gantry
When the set feed operation button 99a on 6a, 56b is pressed, the respective drive circuits 97a, 97b are driven to operate the top plate by the set feed amount. Reference numerals 98a and 98b denote vertical and horizontal movement motors, respectively, which are directly connected to the drive circuits 97a and 97b. In addition, since the horizontal movement operation does not operate when the top board 75 enters the gantry measurement space 50, it must be performed before the vertical movement operation. Is configured to be started. 99b is a manual operation button, and each motor drive circuit is operated only when the button is pressed, regardless of the set feed operation.

The MRI apparatus of the present invention indicates a light localizer having a position detecting function for indicating a region to be imaged and calculating and setting a distance from the indicated position to the center of the magnetic field based on the position data of the light localizer. Since the means for adjusting the feed amount is provided, the top plate on which the subject is placed or the subject can be positioned without moving the subject, and the burden on the subject can be reduced and the imaging efficiency can be improved.

FIG. 2 is a rear perspective view of the MRI apparatus showing that the light localizer 83 with the position detecting function is also arranged on the rear surface of the gantry. FIG. 2 shows the light localizer and its lines 82a and 82b arranged at the upper center of the rear surface of the gantry. And their movement directions 101b and 102b. These are configured separately from the light localizer with a position detection function provided on the front of the gantry, and the data (CPU etc.) 95 that calculates the distance to the center of the magnetic field and determines the set feed amount by the data 95 And recognizes it separately from the data detected from the light localizer, and sets and operates only the vertical position. In the height direction, the vertical positioning line 82e is not arranged because it is considered that the operation range of the vertical positioning line 82e is relatively narrow and the error is small. As described above, the MRI apparatus of the present invention can easily move to the center of the magnetic field from either side by providing the light localizer with the position detection function on both the front and rear surfaces of the gantry, greatly improving the imaging efficiency and troublesome for the imaging technician. This can reduce the image quality, improve the image quality, and significantly reduce the burden on the subject.

[0026]

As described above, according to the present invention, a light localizer which points to a region to be imaged and has a position detecting function, and a position from the pointed position to the center of the magnetic field based on the position data of the light localizer. Since the means for calculating the distance and setting the set feed amount is provided, positioning is possible without moving the top plate or the subject on which the subject is placed, thus reducing the burden on the subject and improving the imaging efficiency. There is an effect that can be achieved.

Further, if the light localizers are provided on both front and rear surfaces of the gantry, the movement to the center of the magnetic field can be easily performed from either side, so that the photographing efficiency can be greatly improved, the trouble of the photographing engineer can be reduced, the image quality can be improved, and the image quality can be improved. This has the effect of greatly reducing the burden on the specimen.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an MRI apparatus according to the present invention.

FIG. 2 is a perspective view showing another embodiment of the MRI apparatus according to the present invention.

3 is a plan view showing a main part of the MRI apparatus of FIG. 1 taken out from a side surface.

4 is a perspective view of a main part of the MRI apparatus of FIG. 1 taken out.

5 is a perspective view of a main part of the MRI apparatus of FIG. 1 taken out.

6 is a block diagram illustrating a positioning function of the MRI apparatus in FIG. 1.

FIG. 7 is a perspective view of a gantry portion of the MRI apparatus.

FIG. 8 is a block diagram illustrating a positioning function of a conventional MRI apparatus.

FIG. 9 is a perspective view of a gantry portion of the MRI apparatus.

FIG. 10 is a perspective view of a conventional positioning light localizer.

[Explanation of symbols]

13 Gantries 56a, 56b Patient table operation panel 71 Patient table 75 Top plate 80a Vertical light localizer 80b Horizontal light localizer 80c Height light localizer 81 Positioning points 82a, 82b, 82c Marker line indicated by light localizer 94 Interface circuit for position data 95 Circuit for recognizing position data and calculating set feed amount 96a Circuit for instructing the drive circuit for the set feed amount for vertical movement 96b Circuit for instructing the drive circuit for the set feed amount for horizontal movement 97a For vertical movement Drive circuit 97b Horizontal movement drive circuit 98a Vertical movement drive motor 98b Horizontal movement drive motor 99a Set feed operation button 99b Manual operation button 99d Light localizer positioning operation button 101a, 102a, 103a Light localizer moving direction 101b, 102b , 103b Moving direction of the line indicated by the light localizer

Claims (1)

[Claims] 1. A gantry having a static magnetic field and a gradient magnetic field generating means and having a large opening in the front, and a high-frequency coil for irradiating an object with electromagnetic waves or detecting a magnetic resonance signal from the object. Image reconstructing means for taking an image representing the physical properties of the subject based on the signal detected by the high-frequency coil, and sending the top plate on which the subject lies to the opening or the sending position thereof A vertical movement in the axial direction of the subject to be retracted from the opening, a horizontal movement in a horizontal direction orthogonal to the vertical movement direction, and a vertical movement of the top outside the opening. And a patient table having a set sending function for sending an arbitrary measurement portion of the subject to the center of the static magnetic field. A magnetic resonance imaging apparatus characterized by having a function of setting a localizer to an arbitrary measurement portion so that the portion is sent to the center of a static magnetic field.