JPH04261642A - Magnetic resonance imaging apparatus - Google Patents

Abstract

PURPOSE:To move a desired photographing part of a person to be inspected to the center of a magnetic field easily and accurately by providing a bed comprising an upper structural body only movable vertically, an intermediate structural body for moving it sideways and a lower structural body for moving the upper structural body vertically together with the intermediate structural body. CONSTITUTION:Rails 26a and 26b are fastened separately on internal surfaces of side members 24a and 24b and a frame 23 of an upper structural body 20 is formed with the members. A top board fixing base 27 moves vertically in a direction L along the rails 26a and 26b together with the top board 1. With the driving of a pinion 41, the upper structural body 20 moves sideways in a direction H together with the top board 1. Left and right links 42 and 43 have a lower end thereof connected to a frame 42 and an upper end thereof connected to a frame 36 of the intermediate structural body 21 with a pin to form a parallelogram-shaped link with the frames 36 and 42. Thus, a hydraulic cylinder 46 is stretched or reduced to move vertically both of the upper structural body 20 and the intermediate structural body 21 always kept horizontal.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a magnetic resonance imaging apparatus using permanent magnets, and in particular, the present invention relates to a magnetic resonance imaging apparatus that uses permanent magnets, and in particular, a desired part of a subject lying on a top plate can be arbitrarily positioned at the center of a magnetic field within a gantry opening. The present invention relates to a magnetic resonance imaging apparatus equipped with a bed suitable for easy and accurate movement and positioning.

0002

2. Description of the Related Art Conventionally, a nuclear magnetic resonance imaging apparatus (hereinafter referred to as MRI) using a permanent magnet has been used, in which a subject can be arbitrarily moved within a gantry opening to align the target imaging region with the center of the magnetic field. (abbreviated as device) has been proposed (for example, Japanese Patent Laid-Open No. 2-55042). This will be explained below with reference to FIGS. 6 to 10. Here, FIG. 6 is a perspective view showing the appearance of the MRI apparatus, FIG. 7 is a perspective view of a bobbin with a coil wound around its outer periphery to form a high-frequency coil, FIG. 8 is a perspective view showing the appearance of the bed, and FIG. 9 is the state of FIG. 8. FIG. 10 is a vertical cross-sectional view of the upper part of the bed with the top plate attached to FIG. 9.

As shown in FIG. 6, the MRI apparatus includes a gantry G having an opening A through which the subject can be inserted into the imaging position, and a top plate made of resin (FRP resin) on which the subject is placed. 1
The structure is such that the bed 2 having a bed 2 is placed in close proximity to the bed 2. 3 is a head rest on which the subject's head is placed. Opening A
As shown in FIG. 7, the bobbin 4 is made of resin and has a rectangular cylindrical shape that is long in the width direction. The width B of the opening A is approximately 1000 mm, which is approximately three times the shoulder width of a human being, as a space that allows the subject to move in a direction perpendicular to the body axis.
The height C of the opening A is set to be about 500 mm wide so as not to give a feeling of pressure to the subject. A coil 5 is wound along the outer periphery of the bobbin 4, and together with the bobbin 4 forms a high frequency coil. As shown in FIG. 8, the bed 2 is
A base 6 that is long in the body axis direction of the subject is fixed on the upper part, and on the base 6 is a support plate 7 made of resin (FRP resin) for supporting the top plate 1. It is installed so that it can move (vertical movement) in the direction of the subject's body axis as indicated by . The top plate 1 supported on the support plate 7 is mounted so as to be movable (laterally movable) on the support plate 7 in a horizontal direction perpendicular to the body axis direction of the subject as indicated by arrow H in the figure. ing. In this case, the lateral movement is manually performed by an operator. Reference numeral 8 denotes a lever provided at the rear end of the support plate 7. By operating the lever 8, the top plate 1 is locked to the support plate 7, so that the top plate 1 cannot be moved in the direction of arrow H. It is made movable only in the direction of arrow L together with the support plate 7,
On the contrary, the lock can be released to enable movement on the support plate 7 in the direction of arrow H.

The vertical movement of the top plate 1 and the support plate 7 and the horizontal movement of the top plate 1 are carried out by being supported by various rollers shown in FIGS. 9 and 10. In FIGS. 9 and 10, reference numeral 9 denotes a plurality of rollers installed at appropriate intervals in the longitudinal direction of the support plate 7, which supports the top plate 1 and the support plate 7 and supports the base 1 during vertical movement.
roll on top. When the roller 9 is moved vertically from the illustrated state, a portion of the roller 9 comes off the base 6, but the detached roller 9 transfers onto the bobbin 4 and rolls on the bobbin 4. Reference numeral 10 denotes a plurality of rollers attached at right angles to the rollers 9 at the front and back of the support plate 7 in the longitudinal direction, and the rollers 10 move the top plate 1 by ±100 m.
It is supported so that it can be moved laterally with a stroke of m or more. 11
are a plurality of rollers installed parallel to the rollers 10 at the front and back of the support plate 7 in the longitudinal direction, and the rollers 11 are fixed to the lower surface of the top plate 1 when the top plate 1 moves laterally, as shown in FIG. The top plate 1 rolls on the rail 12 with the subject's weight.
is designed to prevent it from falling over. Reference numeral 13 denotes a plate fixed to the support plate 7 for aligning the centers of the widths of both the top plate 1 and the bed 2. A counterbore is provided at the center of the width of the plate 13. When the ball of the ball plunger 14 fixed to the top plate 1 is pushed in by the spring of the ball plunger 14, the two coincide. A rack 15 is fixed to the support plate 7 so as to mesh with a pinion fixed to the lever 8.

The vertical movement of the top plate 1 and the support plate 7 is achieved by moving a support plate fixing plate (not shown) fixed to the rear lower surface of the support plate 7 via a chain by a drive device provided on the base 6. The vertical movement of the top plate 1 and the support plate 7 is performed by expanding and contracting a link formed in a pantograph shape (not shown) using a hydraulic cylinder.

[0006]

[Problem to be solved by the invention] The above-mentioned conventional MRI
Both the top plate 1 and the support plate 7 are made of FRP resin, and the apparatus has the advantage of being easy to manufacture because it can be easily molded. There is a problem of rapid wear and tear in areas that are subject to manual or repetitive operations. For this reason, various parts tend to rattle during use, resulting in a short product life. In addition, the subject to be photographed is quite heavy, consisting of the top plate 1 and the patient lying on it, and since the horizontal movement of the top plate 1 is manual, the heavy objects can be started and stopped as desired. It is difficult to accurately position the magnetic field, and there is a problem in that it is difficult to accurately align the desired imaging region with the center of the magnetic field. Furthermore, there were other disadvantages such as a large number of parts and an expensive FRP resin.

[0007] In view of the problems of the above-mentioned prior art, the present invention
A bed with a simple configuration and a long product life that allows the desired part of the patient to be imaged while lying on the top plate to be easily and accurately moved and aligned to the center of the magnetic field within the gantry opening. An object of the present invention is to provide a magnetic resonance imaging apparatus equipped with the following.

[0008]

Means for Solving the Problems In order to achieve the above object, the present invention provides a gantry having an opening formed in a rectangular cylinder shape long in the width direction so that a subject can be inserted into an imaging position, and the opening. A high-frequency coil formed by winding a coil around the outer periphery of a bobbin forming a section, and a top plate on which the subject is placed are inserted into the gantry opening and the cover is retreated from the insertion position to the outside of the gantry opening. In the magnetic resonance imaging apparatus, the top plate is provided with mechanisms for vertically moving the examiner in the body axis direction, horizontally moving the examiner in a horizontal direction perpendicular to the direction of the vertically moving, and vertically moving the examiner outside the gantry opening. a frame formed to have approximately the same length as the frame and having rails fixed to the left and right sides, a top plate fixing base fixed to the lower surface of the frame, and a drive that allows the top plate to be moved only vertically along the rails through a plurality of rollers. an upper structure having a mechanism; an intermediate structure having a drive mechanism that supports the upper structure so that only the lateral movement is possible and arbitrarily moves the supported upper structure laterally; The bed comprises a lower structure provided with a drive mechanism for arbitrarily moving the upper structure up and down together with an intermediate structure.

[0009] The drive mechanism for laterally moving the upper structure is moved from the retracted position of the top plate to a point just before the tip roller of the rollers provided on the lower surface of the top plate transfers to the entrance of the gantry opening. It is preferable to configure it so that it can be moved laterally until it reaches the position.

[0010] The drive mechanism for laterally moving the upper structure includes a drive motor fixed to the upper structure with a pinion fixed to an output shaft, and a driving motor fixedly attached to the upper structure in the lateral movement direction so as to mesh with the pinion. It is desirable to have a configuration consisting of a rack fixedly attached to the intermediate structure along the direction, and a guide member for moving the upper structure in the lateral movement direction, and further comprising a drive mechanism for moving the upper structure laterally. , a driving motor fixed to one end of the intermediate structure with a sprocket fixed to the output shaft, and a sprocket arranged at the other end of the intermediate structure and connected to the sprocket via a chain. , a connecting member that connects both ends of the chain and fixes the connecting portion at a position approximately in the middle of the width of the upper structure, and a guide member that moves the upper structure in the lateral movement direction. .

On the other hand, it is preferable that the roller provided on the lower surface of the top plate be formed into a spherical shape that can rotate in any direction, and that a static magnetic field is formed between the lower outer peripheral surface of the bobbin and the gantry opening. It is desirable to interpose a plate-like member between the lower magnetic pole piece and the lower magnetic pole piece to support the downward load of the top plate on which the subject is placed.

0012

[Operation] With the above structure, the magnetic resonance imaging apparatus of the present invention has a bed that is constructed by stacking each of the upper structure, the intermediate structure, and the lower structure. F that supported the board, moved vertically with the supported top board, and made the top board horizontally movable.
The support plate made of RP resin will be abolished. and,
Each of the above-mentioned structures can be made of any other inexpensive material other than FRP resin, and can be formed into a rigid shape, so that each part will not be damaged due to wear during use. It becomes possible to significantly reduce the occurrence of backlash.

On the other hand, since the movement of each of the structures is performed by a drive mechanism independently provided to each structure,
By appropriately selecting and setting the drive power, movement speed, etc. of each drive mechanism, it is possible to start and stop each movement reliably at the desired position, and the desired imaging area to be targeted is placed at the center of the magnetic field. can be matched exactly.

[0014] Since each of the above-mentioned structures has an independent and simple configuration, the device can have a small number of parts.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a side view showing the appearance of the magnetic resonance imaging apparatus, FIG. 2 is a perspective view showing the appearance of the top plate and the upper structure of the bed, and FIG. 3 is the upper structure and the intermediate structure supporting the upper structure. FIG. 4 is a perspective view showing the appearance of the lower structure of the bed, and FIG. 5 is an installation diagram of the high-frequency coil. In the figures, the same reference numerals as those in FIGS. 6 to 10 above indicate the same things.

In FIG. 1, 20 is an upper structure formed to have almost the same length as the top plate 1 and supports the top plate 1 so that the top plate 1 can only be moved vertically, and 21 is a top structure that supports the top plate 1 and can be moved laterally. The intermediate structure 22 that supports only the upper structure 20 and the intermediate structure 21 is a lower structure installed on the floor surface that supports the upper structure 20 and the intermediate structure 21 so as to be able to move up and down. The bed 2 has a simple structure with a small number of parts, consisting of the above-described upper structure 20, intermediate structure 21, and lower structure 22, and as explained below for each structure, each part has a long product life with extremely little play. It has a long structure. .

In FIG. 2, 24a and 24b are left and right side members having approximately the same length as the top plate 1, and are arranged in parallel with an interval. For example, as shown in the figure, highly rigid members such as a box cross section are used. be done. 25a, 25b, 25c are connecting plates that connect the side members 24a, 24b together;
Reference numerals 6a and 26b are rails having a rectangular cross section fixed to the inner surfaces of the side members 24a and 24b, respectively, and the frame 23 of the upper structure 20 is formed by these members. Reference numeral 27 denotes a top plate fixing base that is connected to the rear lower surface of the top plate 1 by a connecting part 28 such as a bolt, and moves vertically along the rails 26a, 26b in the direction of arrow L together with the top plate 1. Cam followers (rollers) 2 are arranged on the front, rear, left and right sides of the top plate fixing base 27 so as to sandwich the rails 26a and 26b from above and below.
9, and rail 2 to remove play in the direction perpendicular to arrow L.
A cam follower 30 is provided so as to press the side surfaces of 6a and 26b. 31 is the top plate fixing stand 27
This is a clamp plate that clamps the chain 35. 32 is a motor with a reducer for vertical movement attached to the lower surface of the connecting plate 25c, 33 is a sprocket fixed to the output shaft of the motor 32 with a reducer, 34 is a sprocket provided on the connecting plate 25a, and 35 is a Sprocket 33,3
Both ends of the chain 35 are fixed to the clamp plate 31. For this reason, chain 35
By driving, the top plate fixing base 27 and the top plate 1 are vertically moved in the direction of arrow L via the clamp plate 31. Therefore, the imaging site of the subject lying on the top plate 1 can be easily and precisely moved and aligned within the gantry opening A to a desired vertical movement position. Although not shown, there is a frame 23 on the bottom surface of the top plate 1.
A plurality of rollers are arranged to roll on members (not shown), and are configured to prevent the top plate 1 from being bent at positions other than the top plate fixing base 27. Further, the plurality of rollers may be formed into spherical rollers, and may be freely rotatable in any direction.

Next, in FIG. 3, 36 is the intermediate structure 2
1, frame 37 is a linear guide fixedly installed in the direction of arrow H on the frame 36 to a length that is approximately the full width of the frame, and is arranged front and rear with a gap. A linear guide 38 is combined with the linear guide 37, and is fitted to the linear guide 37 so as to be slidable in the direction of arrow H without play, and is fixed to the lower surface of the frame 23. In this case, the cross-sectional shapes of the linear guides 37 and 38 are formed in such a shape that there is no backlash (in the direction of arrow L) and vertical direction between them during sliding. A rack 39 is fixed on the frame 36 in parallel with the linear guide 37. Reference numeral 40 denotes a motor with a reduction gear for lateral movement mounted on the connecting plate 25b of the frame 23, and 41 a pinion that meshes with a rack 39 fixed to the output shaft of the motor 40 with a reduction gear. Therefore, by driving the pinion 41, the upper structure 20 can be moved laterally along with the top plate 1 arbitrarily and easily in the direction of the arrow H, and the starting and stopping during the lateral movement can be performed accurately at the desired position. It is possible to do so. In addition, the position and range that can be moved laterally are as follows:
It is desirable to do this between the retracted position of the vertical movement and the position immediately before the tip roller of the plurality of rollers provided on the underside of the top plate 1 (not shown) transfers to the entrance of the gantry opening A. . By doing so, it becomes possible to smoothly transfer the top plate 1 to the opening A.

Although not shown, the rack 39
A drive mechanism for lateral movement by a combination of and pinion 41,
Similar to the vertical movement drive mechanism, a drive motor with a sprocket fixed to the output shaft is fixed at one end of the intermediate structure 21 in the width direction, and a sprocket is arranged at the other end of the intermediate structure 21. and connect the sprocket to the chain via a chain, both ends of the chain are connected to a connecting member, and the connecting member is fixed at a position approximately in the middle of the width of the upper structure 20,
The chain may be driven to move laterally along the linear guides 37 and 38.

Next, in FIG. 4, 42 indicates the lower structure 22.
The frames 43 and 44 are left and right links arranged before and after the frame 42, and each link has its lower end connected to the frame 42 and its upper end connected to the frame 36 of the intermediate structure 21 by a pin. , and frames 36 and 42 form a parallelogram link. 45 is link 43
The rod 46 connects the left and right middle parts of the rod 45, and the hydraulic cylinder 46 is rotatably attached to one end of the rod 45 and the other end to the frame 42 via a fixing member 47 and a pin 48. It is. Therefore, by expanding and contracting the hydraulic cylinder 46, both the upper structure 20 and the intermediate structure 21 can be moved up and down as desired, always in a horizontal state, regardless of their relative positions. The position of the bed 2 indicated by the dotted line in FIG. 1 is a position lowered by vertical movement.

Next, in FIG. 5, reference numerals 49 and 49 denote a pair of permanent magnets arranged opposite to each other with the bobbin 4 in between;
, 50 are a pair of magnetic pole pieces fixed to the inner surface of each permanent magnet 49, 51 and 51 are yoke plates that are in contact with the outer surface of each permanent magnet 49, and 52 is a support for each yoke plate 51 at a predetermined distance. A static magnetic field is formed in the gap between the pair of magnetic pole pieces 50, 50 using a plurality of (four) yoke bars. 53 is a plate-like member interposed between the lower end surface of the bobbin 4 and the lower magnetic pole piece 50, and the plate-like member 53 is inserted through the bobbin 4 when the subject is inserted into the opening A. A material having high strength is used so that the downward load of the subject and the top plate 1 can be supported without bending the top plate 1 and the bobbin 4. The area of the plate member 53 is formed to a size that can support the load even if the load position of the subject and the top plate 1 changes due to lateral movement.

[0022]

As explained above, the present invention has a bed composed of an upper structure, an intermediate structure, and a lower structure, and each structure is provided with an independent drive mechanism to move the top plate vertically.
Since it is designed to move horizontally and vertically, it is possible to easily and accurately move and position the desired imaging region of a subject lying on the top board to the center of the magnetic field within the gantry opening. This has the effect of making it possible to provide a bed with a simple configuration and a long product life.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the appearance of a magnetic resonance imaging apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance of the top plate and the upper structure of the bed shown in FIG. 1;

FIG. 3 is a perspective view showing the appearance of the upper structure shown in FIG. 1 and an intermediate structure supporting the upper structure.

FIG. 4 is a perspective view showing the appearance of the lower structure of the bed shown in FIG. 1;

FIG. 5 is an installation diagram of a high-frequency coil in the gantry shown in FIG. 1;

FIG. 6 is a perspective view showing the appearance of a conventional MRI apparatus.

FIG. 7 is a perspective view of a conventional bobbin in which a high-frequency coil is formed by winding a coil around the outer periphery of the bobbin.

FIG. 8 is a perspective view showing the appearance of a conventional bed.

FIG. 9 is a perspective view showing the appearance of the device with the top plate removed from the state of FIG. 8;

10 is a vertical sectional view of the upper part of the bed with the top plate attached to FIG. 9; FIG.

[Explanation of symbols]

1 Top plate 2 Bed 4 Bobbin 20 Upper structure 21 Intermediate structure 22 Lower structure 23 Frame 26a Rail 26b Rail 27 Top plate fixing base 32 Motor with reducer (for vertical movement) 35
Chain 37 Linear guide 38 Linear guide 39 Rack 40 Motor with reducer (for lateral movement) 41
Pinion 43 Link 44 Link 46 Hydraulic cylinder (for vertical movement) 53 Plate member A Opening G Gantry

Claims (6)

[Claims] Claim 1: A gantry having an opening formed in a rectangular cylinder shape long in the width direction so that a subject can be inserted into an imaging position; and a gantry formed by winding a coil around the outer circumference of a bobbin forming the opening. A high-frequency coil and a top plate on which the subject is placed are inserted into the gantry opening, and the subject moves vertically in the body axis direction from the insertion position to the outside of the gantry opening. A magnetic resonance imaging apparatus equipped with mechanisms for horizontal lateral movement perpendicular to the direction of the gantry and for vertical movement outside the gantry opening, a frame having approximately the same length as the top plate and having rails fixed to the left and right sides; , an upper structure having a top plate fixing base fixed to the lower surface thereof, and a drive mechanism for moving the top plate only vertically along the rail via a plurality of rollers; An intermediate structure that supports only horizontal movement and has a drive mechanism that arbitrarily moves the supported upper structure laterally, and a drive that arbitrarily moves the upper structure up and down together with the intermediate structure via the intermediate structure. A magnetic resonance imaging apparatus comprising a bed comprising a lower structure provided with a mechanism. 2. A drive mechanism for laterally moving the upper structure,
Claim 1, wherein the top plate is movable laterally from a retreated position to a position immediately before a tip roller of rollers provided on the lower surface of the top plate moves to the entrance of the gantry opening.
The magnetic resonance imaging device described. 3. A drive mechanism for laterally moving the upper structure,
a drive motor fixed to the upper structure with a pinion fixed to an output shaft; a rack fixed to the intermediate structure along the lateral movement direction so as to mesh with the pinion; and the upper structure. 3. The magnetic resonance imaging apparatus according to claim 1, further comprising a guide member that moves the magnetic resonance imaging apparatus in the lateral movement direction. 4. A drive mechanism for laterally moving the upper structure,
A driving motor is fixed to one end of the intermediate structure by fixing a sprocket to an output shaft, and a sprocket is connected to the sprocket via a chain and is arranged at the other end of the intermediate structure. , a connecting member that connects both ends of the chain and fixes the connecting portion at a position approximately in the middle of the width of the upper structure; and a guide member that moves the upper structure in the lateral movement direction. or the magnetic resonance imaging apparatus according to 2. 5. The magnetic resonance imaging apparatus according to claim 1, wherein the roller provided on the lower surface of the top plate is formed into a spherical shape capable of rotating in any direction. 6. between the lower outer peripheral surface of the bobbin and a lower magnetic pole piece that forms a static magnetic field within the gantry opening;
3. The magnetic resonance imaging apparatus according to claim 1, further comprising a plate-like member that supports the downward load of the top plate on which the subject is placed.