Magnetic resonance imaging apparatus, bed for magnetic resonance imaging apparatus and a method of positioning a bed for a magnetic resonance imaging apparatus

According to one embodiment, a magnetic resonance imaging apparatus includes a gantry and a movable bed. A magnet, a gradient coil, and a radio frequency coil are built in the gantry. The movable bed is configured to be positioned to the gantry by a positioning mechanism having different structures at different positions in a longitudinal direction of the bed.

FIELD

Embodiments described herein relate generally to an MRI (magnetic resonance imaging) apparatus, a bed for a magnetic resonance imaging apparatus and a method of positioning a bed for a magnetic resonance imaging apparatus.

BACKGROUND

Conventionally, a movable bed used for an MRI apparatus is used with docking with one side of the gantry.

PRIOR TECHNICAL LITERATURE

A movable bed used in an MRI apparatus is desired to be positioned easily with a simple structure.

Accordingly, an object of the present invention is to provide a magnetic resonance imaging apparatus, a bed for a magnetic resonance imaging apparatus and a method of positioning a bed for a magnetic resonance imaging apparatus which can position a movable bed easily.

DETAILED DESCRIPTION

In general, according to one embodiment, a magnetic resonance imaging apparatus includes a gantry and a movable bed. A magnet, a gradient coil, and a radio frequency coil are built in the gantry. The movable bed is configured to be positioned to the gantry by a positioning mechanism having different structures at different positions in a longitudinal direction of the bed.

Further, according to another embodiment, a bed for a magnetic resonance imaging apparatus includes a bed main body, a first positioning mechanism and a second positioning mechanism. The bed main body includes a top plate configured to set an object. The first positioning mechanism is configured to perform a positioning of the bed main body at a first position. The second positioning mechanism is configured to perform a positioning of the bed main body at a second position different from the first position in a longitudinal direction of the bed main body. The second positioning mechanism has a structure different from a structure of the first positioning mechanism.

Further, according to another embodiment, a method of positioning a movable bed for a magnetic resonance imaging apparatus includes positioning the bed, to a gantry of the magnetic resonance imaging apparatus, at a first position, by a first positioning mechanism; and positioning the bed, to the gantry, at a second position different from the first position in a longitudinal direction of the bed, by a second positioning mechanism having a structure different from a structure of the first positioning mechanism.

A magnetic resonance imaging apparatus, a bed for a magnetic resonance imaging apparatus and a method of positioning a bed for a magnetic resonance imaging apparatus according to embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1is an upper view showing a configuration of a magnetic resonance imaging apparatus according to the first embodiment of the present invention. Moreover,FIG. 2is a front view of the gantry and the bed shown inFIG. 1.

A magnetic resonance imaging apparatus1includes a gantry2, a bed3, and a control system4. Hardware, such as a magnet14, a gradient coil15, RF (radio frequency) coils16, required for MR (magnetic resonance) imaging are built in the gantry2. The control system controls the hardware built in the gantry2and the bed3, and reconstructs MR image data based on MR signals received by RF reception coils.

The bed3is a movable bed which can be detached from and attached to the gantry2,FIG. 1shows an upper view of the bed3and the gantry2in the state where the bed3is not connected with the gantry2. The bed3is configured to be fixable and detachable at mutually different positions in the longitudinal direction L. Then, the bed3can be positioned to the gantry2by fixing the bed3on the plural positions. Especially the bed3is configured to be positioned to the gantry2by positioning mechanisms having mutually different structures at mutually different positions in the longitudinal direction,

In the example shown inFIG. 1, the bed3is fixed at two positions in the longitudinal direction L. Therefore, the bed3is configured by providing the first positioning mechanism6and the second positioning mechanism7with a bed main body5.

The typical bed main body5has a top plate5A for setting an object, a driving mechanism5B for driving the top plate5A and casters5C for moving the bed main body5, as illustrated. The driving mechanism5B is controlled by electric power supplied from the control system4through the gantry2. Meanwhile, the bed main body5is configured to be restricted to move horizontally by locking the drive of the casters5C.

The first positioning mechanism6and the second positioning mechanism7are elements for positioning the bed main body5at the first position and the second position, respectively. Note that, the second position differs from the first position in the longitudinal direction L of the bed main body5.

Specifically, the first positioning mechanism6is for horizontal positioning of the bed main body5at the first position in the side near the gantry2. On the other hand, the second positioning mechanism7is for horizontal positioning of the bed main body5at the second position in the side separated from the gantry2.

Moreover, the first positioning mechanism6and the second positioning mechanism7are configured to perform positioning respectively in the state where the casters5C have contacted with the floor. Therefore, the bed main body5is configured to be positioned in the height direction of the top plate5A by contacting the casters5C with the floor.

For the first positioning mechanism6and the second positioning mechanism7, arbitrary elements can be used so long as they are detachable and can perform the relative positioning of the bed main body5against the gantry2. For example, the positioning mechanism can be configured by a hole and a pin inserted in the hole. Alternatively, the positioning mechanism can be also configured by a slot and a protruding object, such as a hook or a pin, fitting the slot. However, as mentioned above, the second positioning mechanism7has a structure different from that of the first positioning mechanism6.

In the example shown inFIG. 1, a rectangular concave part6A is formed in the bed main body5as the first positioning mechanism6while a pin7A is prepared in the bed main body5as the second positioning mechanism7. On the other hand, a convex part6B, which fits to the rectangular concave part6A consisting of the first positioning mechanism6, is prepared near the floor in the bed3side of the gantry2while a slotted hole7B, which fits to the pin7A consisting of the second positioning mechanism7, is formed at a position, separated from the gantry2, on the floor.

However, targets on which the concave part and the convex part are formed may be converse. For example, a convex part may be provided with the bed main body5as the first positioning mechanism6while a concave part may be formed on the gantry2. Moreover, a slotted hole or a slot may be formed on the bed main body5as the second positioning mechanism7while a pin may be fixed on the floor surface. Furthermore, inserting a pin into a hole formed on the floor surface and forming a slot, fitting the pin, on the bed main body5make it possible to attach and detach the bed3easily.

The bed3is preferred to be fixed detachably to the gantry2at least one place. That is, the positioning accuracy of the bed3to the gantry2can be improved by connecting the bed3with the gantry2directly. On the other hand, the direction of the bed3to the gantry2can be set accurately by fixing the bed3detachably at another place farther from the gantry2.

Moreover, the plate for fixing the bed3in the side separated from the gantry2may be an element of the magnetic resonance imaging apparatus1. The plate for fixing the bed3so as to be detachable is desired to be rigidly connected with the gantry2. In the example shown inFIG. 1, a floor plate8A for installing the gantry2is rigidly connected with a floor plate8B for installing the bed3by fixing members9, such as bolts. Thus, it becomes possible to fix the bed3to the gantry2firmly with a higher accuracy by rigidly connecting the plate with the gantry2.

When a plate is provided, the positioning mechanism of the bed3can be configured easily by forming a hole or a slot on at least one of the bed3and the plate and providing a pin or a hook, inserted in the hole or the slot, with the other. In the example shown inFIG. 1, a slotted hole7B is formed on the plate while a pin7A which fits the slotted hole7B is provided with the bed3.

As shown inFIG. 1, the bed3can be configured to be positioned, at a position in the side far from the gantry2, with the slotted hole7B and the pin7A which is inserted in the slotted hole7B. Thereby, the mechanical errors in the longitudinal direction L of the bed3can be reduced.

Note that, the second positioning mechanism7to position the bed3at a position in the side away from the gantry2may be also configured to operate in conjunction with the positioning of the bed3at a position of the bed3in the gantry2side by the first positioning mechanism6.

FIG. 3is a view showing an example of configuration of the second positioning mechanism7for fixing the bed3shown inFIG. 1in case where the second positioning mechanism7is configured to move with interlocking with the fixation at the position in the gantry2side. Moreover,FIG. 4is a view showing the state of the second positioning mechanism7when the bed3shown inFIG. 3has been set to the gantry2.

FIG. 3shows the state where the bed3has been removed from the gantry2whileFIG. 4shows the state where the bed3has been set to the gantry2. As shown inFIG. 3, rotary shafts10A,10B can be prepared in the gantry2side of the bed3and the side separated from the gantry2, respectively. Further, L-shaped members11A,11B can be attached to the rotary shafts10A,10B, respectively. The ends of the L-shaped members11A,11B are connected with each other by connecting members12, such as wires or connecting rods, whose both ends are free ends.

The L-shaped member11A provided in the gantry2side is attached to the bed3so as to be an inverted L-shape. To the end of the L-shaped member11A in the gantry2side, a contacting plate13is fixed. The contacting plate13contacts with the convex part6B in the gantry2side when the bed3is set to the gantry2. Moreover, the other end side of the L-shaped member11A is rotatably connected with the connecting member12.

On the other hand, the bed main body5side of the L-shaped member11B provided in the side away from the gantry2is rotatably connected with the connecting member12. Moreover, the pin7A which fits the slotted hole7B formed on the floor plate8B is fixed to the other side of the L-shaped member11B.

The L-shaped member11A provided on the bed main body5in the gantry2side is laid counterclockwise with a spring. On the other hand, the L-shaped member11B provided on the bed main body5in the side away from the gantry2is laid clockwise with a spring. For this reason, in the state that the contacting plate13of the L-shaped member11A provided in the gantry2side does not contact with the convex part6B in the gantry2side, the axis of the pin7A becomes a diagonal direction by the action of the springs and the position of the pin7A becomes high. Therefore, the bed3can be moved without the tip of the pin7A contacting with the floor plate8B.

On the other hand, when the contacting plate13is contacted with the convex part6B in the gantry2side, the L-shaped member11A provided in the gantry2side rotates clockwise. For this reason, the L-shaped member11B provided in the side far from gantry2and connected with the connecting member12rotates counterclockwise. As a result, the pin7A projects in the floor plate8B side and the pin7A can be inserted in the slotted hole7B. That is, the bed3can be fixed at the two places.

In addition, chamfering members, such as the pin7A, the slotted hole7B, the convex part6B and the concave part6A, to be fitting targets as illustrated makes it possible to set and detach the bed3easily.

FIG. 5is a view showing an example of forming a taper face on the slotted hole7B shown inFIG. 1.

FIG. 5is a sectional view of the floor plate8B as viewed from the longitudinal direction of the slotted hole7B. As shown inFIG. 5, it becomes possible to guide the pin7A into the slotted hole7B easily by forming a tapered face on the slotted hole7B. It is also suitable to form a tapered face on the tip of the pin7A as illustrated.

The above mentioned magnetic resonance imaging apparatus1is an apparatus configured to position the movable bed3at two or more places in the longitudinal direction L by plural positioning mechanisms having mutually different structures.

For this reason, with the magnetic resonance imaging apparatus1, the relative positional relationship between the bed3and the gantry2can be ensured with a higher accuracy. Especially, the conventional bed had been fixed to the gantry only in the gantry side. For this reason, in order to counter the component of the external force which is orthogonal to the longitudinal direction L of the bed, a very powerful docking mechanism was needed to be provided. Moreover, ensuring the positioning accuracy in the direction which is orthogonal to the longitudinal direction L of the bed was difficult.

On the contrary, with the magnetic resonance imaging apparatus1, the bed3can be firmly fixed to the gantry2with a simple structure. Moreover, because the bed3is also fixed in the side, away from the gantry2, of the bed3, the positioning accuracy in the direction which is orthogonal to the longitudinal direction L of the bed3can be improved. In addition, the durability and the reliability of the docking mechanism which is used repeatedly can be improved because the docking mechanism of the bed3can be simplified.

Furthermore, with the magnetic resonance imaging apparatus1, the movable bed3can be positioned easily. That is, at different positions in the longitudinal direction L of the bed3, the positioning mechanisms, which have structures each depending on a positioning accuracy required corresponding to a distance from the gantry2, are provided.

Specifically, at the first position in the side close to the gantry2, high-precision positioning in the longitudinal direction L of the bed main body5and in the direction orthogonal to the longitudinal direction L is performed by the first positioning mechanism6. On the other hand, at the second position in the side away from the gantry2, only rough positioning in the direction orthogonal to the longitudinal direction L of the bed main body5is performed by the second positioning mechanism7.

For this reason, a time-consuming positioning task to ensure an excessive positioning accuracy can be avoided. In other words, by changing a structure of positioning mechanism depending on a position in the longitudinal direction L of the bed3, a positioning mechanism which can be set easily and satisfies at least a required positioning accuracy can be adopted.

FIG. 6is an upper view showing a configuration of a magnetic resonance imaging apparatus according to the second embodiment of the present invention. Moreover,FIG. 7is a front view of the gantry and the bed shown inFIG. 6. However, the direction of the bed shown inFIG. 7is not coincident with that shown inFIG. 6.

In a magnetic resonance imaging apparatus1A in the second embodiment, a structure of the first positioning mechanism6is different from that in the magnetic resonance imaging apparatus1in the first embodiment. Since the other configurations and actions of the magnetic resonance imaging apparatus1A in the second embodiment do not differ from those of the magnetic resonance imaging apparatus1in the first embodiment substantially, same signs are attached to the same configurations and explanations thereof are omitted.

As shown inFIG. 6, the concave part6A in the bed3side and the convex part6B in the gantry2side can constitute the first positioning mechanism6. In addition, the convex part6B can be configured to rotate horizontally by providing a rotary shaft6C with the convex part6B. Therefore, even if the bed3is moved closer to the gantry2from an oblique direction, the concave part6A in the bed3side can be fitted to the convex part6B in the gantry2side.

Furthermore, a U-shaped convex part6D is fixed to the gantry2side as an element of the first positioning mechanism6. On the other hand, a convex part6E, which has a concave fitting to the U-shaped convex part6D, is fixed to the bed3side as an element of the first positioning mechanism6.

Therefore, when the convex part6D in the gantry2side is pushed into the convex part6E in the bed3side by making the bed3approach the gantry2, the longitudinal direction of the bed3gradually turns into the suitable direction corresponding to the direction of the gantry2. As a result, the pin7A in the bed3side which composes the second positioning mechanism7can be fitted into the slotted hole713on the floor plate8B.

On the contrary, in the state that the tip of the U-shaped convex part6D has been partially inserted in the convex part6E having the U-shaped dent, the direction of the bed3can be adjusted. Therefore, after temporarily fixing the bed3by partially inserting the tip of the U-shaped convex part6D in the convex part6E having the U-shaped dent, the bed3can be locked by fitting the pin7A, in the bed3side, into the slotted hole7B of the floor plate8B.

Thus, the bed3can be configured to be positioned in the horizontal direction at the first position in the side close to the gantry2and subsequently be positioned in the horizontal direction at the second position in the side far from the gantry2. That is, the bed3can be configured to be temporarily fixed by the positioning in the horizontal direction at the first position in the side close to the gantry2and subsequently be locked by the positioning in the horizontal direction at the second position in the side away from the gantry2.

Note that, the first positioning mechanism6may have another structure as long as the structure allows adjusting the direction of the bed3, in the horizontal direction, against the gantry2. For example, the U-shaped convex part6D and the convex part6E having the U-shaped dent may be omitted. Also in such a case, the temporary joint and the adjustment of direction of the bed3can be performed by rotating the convex part6B in the gantry2side.

Moreover, as another example, the convex part6B in the gantry2side may be unable to be rotated while the length of the U-shaped convex part6D and the convex part6E having the U-shaped dent may be made to be enough longer than the length of the convex part6B. In that case, the temporary joint and the adjustment of direction of the bed3can be performed by the U-shaped convex part6D and the convex part6E having the U-shaped dent.

According to the magnetic resonance imaging apparatus1A in the second embodiment as mentioned above, an effect similar to that in the magnetic resonance imaging apparatus1in the first embodiment can be obtained. In addition, even if the bed3is moved closer to the gantry2from an oblique direction, the bed3can be positioned. For this reason, it becomes possible to position the bed3still more easily.

FIG. 8is an upper view showing a configuration of the first positioning mechanism included in a magnetic resonance imaging apparatus according to the third embodiment of the present invention.

In a magnetic resonance imaging apparatus in the third embodiment, a structure of the first positioning mechanism6is different from that in the magnetic resonance imaging apparatus1in the first embodiment. The other configurations and actions of the magnetic resonance imaging apparatus in the third embodiment do not differ from those of the magnetic resonance imaging apparatus1in the first embodiment substantially. Therefore, only a structure of the first positioning mechanism6is illustrated with attaching same signs to the same configurations, and explanations of the same configurations are omitted.

The first positioning mechanism6included in the magnetic resonance imaging apparatus in the third embodiment has at least one slotted hole20and pin21whose cross section is a long circle. It is preferable to prepare two or more combinations consisting of the slotted holes20and the pins21in the direction normal to the longitudinal direction L of the bed3after the positioning.

When the slotted holes20are formed on the floor plate8A, the pins21are attached to the bed3side. On the contrary, when the pins21are prepared on the floor plate8A, the slotted holes20are formed in the bed3side. A method of attaching the pins21to the bed3or the floor plate8A is arbitrary. However, the pins21are attached to the bed3or the floor plate8A so that the pins21can rotate around their axes.

On the other hand, the longitudinal direction of each slotted hole20which constitutes the first positioning mechanism6is directed so as to be normal to the longitudinal direction of the slotted hole7B of the floor plate8B which constitutes the second positioning mechanism7. That is, the longitudinal direction of each slotted hole20which constitutes the first positioning mechanism6is normal to the longitudinal direction L of the bed3after the positioning.

In the illustrated example, each slotted hole20is formed on the floor plate8A. Therefore, the pins21are attached to the bed3side by an arbitrary method. For example, slotted holes are also formed on the bed3and the pins21are inserted into the slotted holes of the bed3so that the tips of the pins21project from the bed3.

Note that, it is practical to prepare the convex part6B in the gantry2side and to prepare the concave part6A in the bed3side, respectively, as shown inFIG. 1, from a viewpoint of supplying electric power to the driving mechanism5B of the top plate5A and the like. Further, a sufficient interspace is formed between the convex part6B in the gantry2side and the concave part6A in the bed3side.

When the longitudinal direction of the pin21is turned to the longitudinal direction of the slotted hole20as shown inFIG. 8(A), interspace is made between the pin21and the slotted hole20. Therefore, the pin21can be slid, in the longitudinal direction of the slotted hole20, in the slotted hole20. On the other hand, when the longitudinal direction of the pin21is turned to the vertical direction to the longitudinal direction of the slotted hole20as shown inFIG. 8(B), the pin21fits the slotted hole20.

Therefore, when the pin21is inserted in the slotted hole20in the state where the longitudinal direction of the pin21has been turned to the longitudinal direction of the slotted hole20, the bed3can be temporarily fixed in the gantry2side. Further, the position of the bed3can be finely adjusted in the longitudinal direction of the slotted hole20. For this reason, the pin7A in the bed3side which composes the second positioning mechanism7can be fitted with the slotted hole7B of the floor plate8B, with adjusting the position of the bed3in the direction orthogonal to the longitudinal direction L of the bed3. After that, the bed3can be locked in the gantry2side by rotating the pin21which composes the first positioning mechanism6.

That is, the first positioning mechanism6included in the magnetic resonance imaging apparatus in the third embodiment has a structure which can adjust the position of the bed3in the direction orthogonal to the longitudinal direction L.

Therefore, according to the magnetic resonance imaging apparatus in the third embodiment, an effect similar to that in the magnetic resonance imaging apparatus1in the first embodiment can be obtained. In addition, the bed3can be positioned horizontally at the second position in the side separated from the gantry2after horizontal positioning at the first position in the side near the gantry2. Moreover, the bed3can be temporary installed by the horizontal positioning at the first position in the side near the gantry2and subsequently the bed3can be locked by the horizontal positioning at the second position in the side separated from the gantry2.

Note that, the pin21which composes the first positioning mechanism6may be a normal pin whose cross section is circular. In that case, making a diameter of a circular pin into a size fitted with the slotted hole20allows a more accurate positioning in the longitudinal direction L of the bed3even if there is a gap between the convex part6B in the gantry2side and the concave part6A in the bed3side.

FIG. 9is a longitudinal sectional view showing a configuration of the first positioning mechanism included in a magnetic resonance imaging apparatus according to the fourth embodiment of the present invention.

In a magnetic resonance imaging apparatus in the fourth embodiment, a structure of the first positioning mechanism6is different from that in the magnetic resonance imaging apparatus1in the first embodiment. The other configurations and actions of the magnetic resonance imaging apparatus in the fourth embodiment do not differ from those of the magnetic resonance imaging apparatus1in the first embodiment substantially. Therefore, only a structure of the first positioning mechanism6is illustrated with attaching same signs to the same configurations, and explanations of the same configurations are omitted.

The first positioning mechanism6included in the magnetic resonance imaging apparatus in the fourth embodiment has at least one blind hole30whose cross section is circular and at least one stepped pin31whose cross section is circular. It is preferable to prepare two or more combinations consisting of the blind holes30and the stepped pins31in the direction normal to the longitudinal direction L of the bed3after the positioning.

The blind holes30are formed on the floor plate8A. On the other hand, the stepped pins31are attached to the bed3side by an arbitrary method. For example, through holes are formed on the bed3and the stepped pins31are inserted into the through holes of the bed3so that the tips of the stepped pins31project from the bed3.

Note that, it is practical to prepare the convex part6B in the gantry2side and to prepare the concave part6A in the bed3side, respectively, as shown inFIG. 1, from a viewpoint of supplying electric power to the driving mechanism5B of the top plate5A and the like. Further, a sufficient interspace is formed between the convex part6B in the gantry2side and the concave part6A in the bed3side.

The stepped pin31can have a structure that a circular truncated cone is inversely connected with one end of a cylindrical pin so that the outer diameter of the tip becomes thinner. In the illustrated example, the stepped pin31has a structure having two connected circular truncated cones whose inclinations are different.

The outer diameter of the taper part31A of the stepped pin31is smaller than the inner diameter of the blind hole30. Therefore, in a state where the stepped pin31has been shallowly inserted in the blind hole30as much as the taper part31A of the stepped pin31touches the edge of the blind hole30, the stepped pin31can be displaced slightly against the blind hole30.

On the other hand, the outer diameter of the non-taper part31B of the stepped pin31is made to have a size which fits the blind hole30. Therefore, in a state where the stepped pin31has been inserted in the blind hole30deeply enough up to the non-taper part31B, the stepped pin31fits the blind hole30.

Therefore, when the stepped pin31is shallowly inserted in the blind hole30, the bed3can be temporarily fixed in the gantry2side. In addition, the position of the bed3can be finely adjusted depending on the gap between the taper part31A and the blind hole30. For this reason, the pin7A in the bed3side which composes the second positioning mechanism7can be fitted in the slotted hole7B of the floor plate8B, with adjusting the position of the bed3. After that, the bed3can be locked in the gantry2side by strongly pushing the stepped pin31, which composes the first positioning mechanism6, into the blind hole30.

That is, the first positioning mechanism6included in the magnetic resonance imaging apparatus in the fourth embodiment has the structure which can finely adjust the position of the bed3. Consequently, according to the magnetic resonance imaging apparatus in the fourth embodiment, an effect similar to that of the magnetic resonance imaging apparatus in the third embodiment can be obtained.

Note that, the blind hole30which constitutes the first positioning mechanism6may be tapered. In that case, the tapered and stepped pin31, in which an inclination is smaller than that of the blind hole30, or a cylindrical usual pin can be used.

For example, the first positioning mechanism6in the third or fourth embodiment can be also combined with the first positioning mechanism6in the first or second embodiment. In addition, in each embodiment, the second positioning mechanism7can also be configured by elements other than the slotted hole7B and the pin7A. For example, the second positioning mechanism7may also be configured by a hole, whose cross section is circular, and a pin7A.