EP0316316A1

EP0316316A1 - Medical examination table for nmr or tomodensitometry

Info

Publication number: EP0316316A1
Application number: EP87904538A
Authority: EP
Inventors: Jacques Sireul; René Gauthier
Original assignee: Thomson CGR
Current assignee: General Electric CGR SA
Priority date: 1986-07-18
Filing date: 1987-07-10
Publication date: 1989-05-24
Also published as: WO1988000451A1; US4944501A; JPH01503200A; FR2601579A1

Abstract

Lit d'examen comportant un plateau (5), un châssis (4), et des moyens intermédiaires (6) de déplacement du plateau par rapport au châssis pour l'introduire dans un appareil (1) d'examen. Les moyens pour déplacer comportent un équipage mobile (7) de forme allongée dont une extrémité (8) est déplaçable par rapport au châssis et dont l'autre extrémité (9) est déplaçable par rapport au plateau. On montre que de cette manière on augmente les possibilités de débattement du plateau par rapport à son châssis. En outre les moyens d'entraînement sont débrayables (25) et permettent par la simple manoeuvre d'une poignée (30) de retirer en urgence le plateau de la machine d'examen en cas de malaise du patient ou en cas de panne électrique.Examination bed comprising a plate (5), a frame (4), and intermediate means (6) for moving the plate relative to the frame in order to introduce it into an examination apparatus (1). The means for moving include a movable unit (7) of elongated shape, one end (8) of which can be moved relative to the frame and the other end (9) of which is movable relative to the plate. It is shown that in this way the possibilities of movement of the plate relative to its frame are increased. In addition, the drive means are disengageable (25) and make it possible, by the simple operation of a handle (30), to urgently remove the tray from the examination machine in the event of patient discomfort or in the event of an electrical failure.

Description

Examination bed for NMR or computed tomography apparatus.

The subject of the present invention is an examination bed, in particular for a nuclear magnetic resonance (NMR) or computed tomography device. It mainly finds its application in the medical field where it is known to subject patients in the lying position to non-invasive examinations with such devices.

The peculiarity of this type of exams is that they generally last a long time. To increase patient comfort, it may then be necessary to ventilate the examination tunnel of the device, and to illuminate and communicate with the patient. In any event, it is also necessary to ensure constant monitoring of it. In fact, patients subjected to such examinations are generally not in good health; they may be so upset by the examination that they suffer discomfort. It is therefore important to remove them from the machine as soon as possible. In normal use, the insertion of the patient into the machine, on a tray or a patient support panel, is caused by the starting of motors. These motors can be electric. In the case of NMR, it is desirable that they be installed as far as possible from the examination tunnel so as not to disturb the homogeneity of the magnetic field by their metallic mass. However, it may happen that the patient's discomfort is due to a power failure. The patient feels the cut of lighting, ventilation, and the means of monitoring with anguish. An intervention to extract the patient from the machine is then difficult since the panel manipulation motors are precisely down for lack of current. However, because of the mechanical transformation reports, the reduction in the number of these motors, it is unthinkable to manually rotate the transmission chain upside down.

In addition, the examination beds must be able to be used to introduce patients into the machines, and possibly to bring them back to their room when the examination is finished. So the beds are unplugged machines. This necessary constraint of mobility of the beds may be combined with the nature of the examinations undertaken. Indeed, in these, images, seen in section, of parts of the patient's body are produced. These images, these sections, correspond to particular places in the patient's body. It is therefore necessary to locate and move exactly the part to be imaged of the body directly above the imaging means. Consequently, when the bed is plugged into the machine, it is necessary to exactly match means for moving the patient-carrying panel on the bed with means for moving this panel in the machine. To avoid this difficulty, long panels, for example 3.50 meters, have been devised, which always have one end meshed with the bed, the other end being introduced freely into the device. It can be shown that, although already very long, this panel may be insufficiently long to allow an examination of the whole body. It is then necessary to reverse the direction of presentation of the patient when this need arises. In addition, a long bed is unwieldy in the corridors of hospitals.

The object of the present invention is to remedy the drawbacks mentioned by proposing beds the panel and the drive means of which comprise means to facilitate the handling of the patient. On the one hand the panel has been made removable to allow emergency withdrawals. This quality can only be conferred with particularities of guiding the panel on its chassis and in the apparatus, particulars of offset setting in position of the panel relative to the apparatus, and these particularities being associated with a means of disengaging the panel of the drive means which ensure its movement. These declutching means allow an exact repositioning after the emergency intervention. In addition, the removable nature of the panel makes it possible to reduce the cost of the equipment to be constructed: it suffices to construct a bed frame and several removable panels, placed in turn on the bed frame to be able to be introduced into the machine. As a result, preparing patients to undergo the examination no longer requires immobilizing the bed and even less the device. On the other hand, the displacement of the panel relative to the chassis of the bed in order to be able to be introduced into the apparatus is effected by means of an auxiliary arm, called a differential, of length close to the length of the panel and / or of the chassis. (2 meters). One end of this arm drives the panel while the other rests on the frame. In the invention, the function of the patient-carrying panel proper and the means of moving the panel (over a distance greater than the useful length thereof) have thus been separated. As a result, the examination bed according to the invention regains a conventional length, adapted to its conveying in hospital corridors.

The present invention relates to an examination bed, in particular for NMR or computed tomography apparatus, comprising a frame, an examination plate, and means for moving the plate relative to the. chassis and with respect to the apparatus, characterized in that the means for moving comprise an assembly movable with respect to the plate and to the chassis, of elongated shape, one end of which is displaceable relative to the chassis, and the other end of which is displaceable relative to the plateau.

The invention will be better understood on reading the following description and the examination of the accompanying figures. These are given for information only and in no way limit the invention. In the figures, the same references designate the same elements. They show :

- Figure 1 a schematic representation of an examination bed according to the invention;

- Figure 2: an exploded perspective view of the removable tray of the examination bed according to the invention; FIG. 3: a differential arm for maneuvering the plate;

- Figure 4: a perspective view of the guide path of the plate in its frame and in the device.

Figure 1 shows schematically in section an examination bed according to the invention. An NMR device or a tomodensi tometer 1 is designed to receive, substantially along its axis of insertion 2, the body of a patient (not shown) supported by an examination bed 3 according to the invention. This examination bed comprises a frame 4, a plate 5, and drive means 6 for moving the plate relative to the frame and relative to the device. What characterizes the invention is the presence in the drive means 6 of a mobile equipment of elongated shape. This mobile assembly comprises an arm 7, one end 8 of which can be moved relative to the chassis and the other end 9 of which can be moved relative to the plate. Independently of the support and support forces, which will be explained later, it is understood that each point of the plate can move relative to any point of the chassis with a length equal to the sum of the useful stroke 10 of the end 8 in relation to the chassis and the useful stroke

11 of the end 9 relative to the plate. In addition, the arm has the effect of shifting the two extreme positions of the plate relative to the center of the chassis. In the representation of Figure 1 the plate is in an extreme position suitable for preparing for its insertion into the machine. In the other extreme position the plate 5 is completely advanced in the machine 1, and the rear end

12 of the plate can be distant from the front end 13 of the chassis by a distance substantially equal to the length of the arm 7.

In the example shown, the moving assembly 6 comprises two toothed wheels 14 and 15 rotating on shafts secured to the ends respectively of 8 and 9 of the arm. The toothed wheel 14 is supported on a rack 16 secured to the chassis while the wheel 15 is supported on a rack 17 linked to the plate. Sprockets, preferably toothed, 18 and 19 are respectively secured to the wheels 14 and 15. The sprockets rotate on themselves around axes collinear with the axes of the wheels. An endless belt 20, preferably notched, is tensioned and meshes around the pinions. By a motor means, diagrammatically represented by a jar 21, one can push on the end 8 of the arm 7. The rack 16 then turns the wheel 14, this one drives the pinion 18 and, through the inter medial of the belt 20, the pinion 19 is then driven. The pinion 19 in turn causes the movement of the rack 17 of the plate 5. The longitudinal movement of the rack 17 is limited by two stops 22 and 23 integral with the plate 5. Consequently the plate 5 moves relative to the end 9 of the arm of a length linked to the movement of the end 8 of the arm relative to the chassis 4. The movement transformation ratio can be adapted by adjusting the diameter of the wheels 14 or 15 and / or the diameter of the pinions 18 and 19 secured to these wheels. In a preferred embodiment the transformation ratio is 1.

The realization of the invention could be obtained by other means. For example, it would be possible to produce the moving element 6 with a triple cylinder, that is to say with at least 3 nested rods. A first rod would have one end fixed to the plate, and a third, external rod, would have one end, that opposite to the end of the first rod, fixed to the chassis. Under these conditions, it is equivalent to consider the second rod as being the movable assembly and as having a first end which can be moved relative to the plate and a second end which can be moved with respect to the chassis. This hydraulic cylinder solution can be replaced by an equivalent screw solution with at least three screws nested one inside the other.

Apart from the end elements, the intermediate elements, bolts or screws, constitute the mobile assembly. When the intermediate elements are unique, the mobile assembly is rigid and non-deformable. It corresponds to a rigid bar 7. If the intermediate elements are more numerous, for example if they comprise at least two nested rods, the length of the intermediate element can be variable. In all cases, the invention also provides the advantage of making it possible to approach the chassis 4 of the device 1, leaving between these two parts a gap 24 which can be used for any operation of preparing the patient before being introduced into the machine. For example, it is possible for an operator to come and place himself in space 24 to arrange the position of the head of the patient on the plate 5, in particular when this head carries part of the measurement means necessary for the examination to be undertaken, in NMR in particular. Indeed, the head examination must be carried out while ensuring that the head cannot move during the examination. It should therefore be maintained to prevent it from moving in the image. This maintenance, which is annoying for the patient, must be undertaken as late as possible so as not to panic the patient. In practice, it is carried out Just before introduction into the machine 1. Without the presence of the movable assembly 6 it would be necessary, to ensure the most interesting useful stroke of the plate, to approach this plate as far as possible from the front d entry of the machine.

The plate 5 is further provided with means for making it removable in an emergency. Schematically Figure 1 shows the plate 5 now a drive rack 17 on which comes to engage the movable assembly 6 to move the plate. The rack, kept in longitudinal displacement by the two stops 22 and 23 integral with the plate, can however undergo a vertical movement of retraction, of disengagement, tending to raise it. In this way the teeth of the wheel 15 of the mobile assembly escape from the notches of the rack 17. In one example the disengaging movement is obtained by means of a cam plate 25 which maintains, in notches in the general shape of V such as 26 and 27, support shafts 28 and 29 respectively, of the rack 17. By way of simplification, the plate 25 is designed to move longitudinally by means of handles 30 or 31 located on either side of the plate 5. It is kept in horizontal displacement by means which will be described later and which play the same role as longitudinal windows such as 32 of the plate 25 sliding along the pins 33 of the plate 5.

By actuating one or the other of the handles, the plate 25 moves to the right or to the left, and drives the shafts 28 and 29 in an upward movement. Under these conditions the rack rises and escapes from the teeth of the wheel 15. By doing so we have disengaged the means for moving the plate 5. It is then possible to slide this plate on its support means. To facilitate the operation of the handle 30 or 31, this handle is approached by another handle, respectively 34 or 35 secured to the plate, which has a longitudinal offset, the value of which is substantially equal to the useful length of movement of the plate 25 relative to the plateau. In practice, taking into account the depth of the teeth of the wheel 15 and the rack 17, and the inclination of the V of the notches 26 or 27 (substantially 30 °), it is possible to grasp the handles 30 and 34 or

31 and 35. By closing the hand, the rack 17 is disengaged. The force required to achieve this result is low since the rack is relatively light. In one example, this effort has been evaluated at a force of the order of 2 kg force. Then by holding the two handles against each other it is possible to move the plate 5 in the desired direction to extract it from the machine 1.

Figures 2 to 4 show a particular embodiment of the plate 5, the movable assembly 6, and the chassis 4. As an additional essential characteristic the examination bed according to the invention comprises means 36 for measuring the position of the end 8 of the movable assembly 6 relative to the chassis 4. The means 36 may include a tachometer generator or resolvers mounted on the pinion shaft 18. As the chassis is designed to be placed at a predetermined space 24 of the apparatus 1, and as the plate is, in the normal position for transporting the bed at an extreme predetermined location relative to the chassis, it is possible to know by counting the number of revolutions made "by the wheel 14, or the pinion 18, where any section of the pan is in the machine when it is advanced there. This arrangement has the advantage of allowing very tolerant placement of the pan 5 in the machine. he conditions of alignment of the plate 5 with the machine are no longer critical even for the measurement of penetration into the machine. This allows the construction of a trapezoidal section plate (Figure 2), intended to slide on guides of corresponding shape in the device and in the chassis (Figure 4). The apparatus and the chassis preferably have support areas 37-38 and 39-40 respectively for receiving support rollers such as 41-42 (FIG. 2) of the plate 5. In a preferred example these rollers are made of fibers of epoxy glass and are coated with rubber. This gives flexibility to the support and avoids subjecting the patient to unpleasant tremors. To guide the plate in the machine and in the bed frame, these include inclined planes 43-44 and 45-46 respectively on which come to bear rollers such as 47 of the plate 5. In practice the angle of inclination of the Inclined planes is of the order of 30 °. It is a compromise between a guiding efficiency to be obtained, and limits of loosening of the rubber coatings of the glass rollers. In an example to support the tray, we leave about two dozen rollers such as 41-42. To guide it, place half a dozen on each side. The tray may further include side handles such as 48 to 51 regularly distributed on each side along the panel.

With these handles you can grab the tray and place it on a cart to move it around the hospital.

In the preferred embodiment, the rack release device is slightly different. The rack 17 is embedded in a groove 51 inside the plate. It is inserted between the two stops, including the visible stop 23, integral with the plate. On either side of the rack 17, in the groove 51, are introduced on edge two plates 25 and 52, intended to play the same role and to ensure symmetry of the lifting effort of the rack 17. The handle 31 is provided to move the two plates 25 and 52 longitudinally at the same time. Compared to Figure 1 the device for guiding the plates relative to the plate 5 is modified. The plates are each provided at their lower edge with a shoe such as 53 to take support under the plate 5 and thus play the same role as the pins 33 in the windows 32. In a preferred manner the cams 26 and 27 have flats on the edges and in the center of the V to constitute situations of rest of the lifting effort and holding the rack 17. Therefore the low and high positions of the rack are mechanically stable. The central flat part of the cams, for example the flat part 54, is intended to exert a pressure from top to bottom on the support shafts, for example the shaft 55, of the rack so as to avoid, since the weight of this rack is low , that this one does not raise all alone under the driving effect of the wheel 15. In one example rather than two sets 26-27 of cam notches, the plates 25 and 52 comprise about ten of them. This avoids having to overly stiffen the rack 17. The movable assembly comprises the arm 7 in which the toothed wheels 14 and 15 can move at each of the ends. The arm 7 has the shape of a box provided with two windows, for example window 57, to allow the teeth of the wheels 14 or 15 to protrude outside the respectively lower 58 and upper 59 surface of the box 7. The arm also has a front roller 60 to allow its support in machine 1 when engaged. For this purpose the entry edge of the machine has a chamfer 61 (Figures 1 and 4) to receive this roller and allow the insertion of the arm into a groove 62 formed in the tunnel of the machine. In this way, during most of its transfer, the arm rests on the one hand on the rack 16 by its toothed wheel 14 and on the other hand in the groove 62 by the roller 60. At the outlet of the chassis 4 is disposed a diabolo 63 intended to take support under the box 7 while the head 9 of the arm 7 crosses the space 24. The conical ends 64 and 65 of the diabolo 63 allow misalignments between the chassis 4 and the device 1 The influence of the diabolo decreasing as the arm enters the machine, it is planned to provide the lateral edges of the arm 7 with pads such as 66 or 67, preferably made of polytetrafluoroethylene, to take support. on the vertical edges of the grooves of the chassis 4 and of the machine 1. The overall height of the arm is calculated so that this arm can find its exact place in the grooves 51 and 61, or between the racks 16 and 17, without exerting any support of the tray. The bed and / or the frame of the invention can also be provided with all the ancillary devices mentioned above. In addition, and preferably, the bed is adjustable in height to suit all kinds of machines and facilitate the loading of a non-bedridden patient by allowing him to sit on the tray (close to the ground). The raising of the bed is caused by the rotation of the legs of an X. In the preferred embodiment, the base 68 of one of the legs, the leg 69, is held fixed relative to the machine 1, while the base 70 of the other leg can slide in the direction of the base 68 under the action of a motor 71. Under these conditions the gap 24 between the bed and the machine varies as a function of the height position of the bed in order to facilitate even more , in the low position, the passage of the operator. During its elevation the bed undergoes a rotational movement to reduce the distance which separates it from the machine.

Claims

1 - Examination bed (3), in particular for NMR or computed tomography apparatus (1) comprising a frame (4), an examination plate (5), and means (6) for moving the plate relative to the chassis and relative to the device characterized in that the means for moving comprise a movable assembly (6) relative to the plate and to the chassis, of elongated shape (7), one end of which (8) is movable relative to the chassis , and whose other end (9) and movable relative to the plate.

2 - Bed according to claim 1, characterized in that the movable assembly comprises an arm (7) provided at its ends with movable drive means (14,15) for driving the arm in displacement respectively relative to the chassis and the tray relative to the arm.

3 - Bed according to claim 1 or claim 2, characterized in that it comprises means (18-20) so that the movements relative to the ends are mechanically dependent.

4 - Bed according to claim 3, characterized in that the arm comprises two toothed wheels (14,15) for meshing in two racks (16,17) respectively linked to the frame and the plate.

5 - Bed according to claim 4, characterized in that the displacement means comprise a toothed belt (20) for meshing in pinions (18-19) of drive.

6 - Bed according to claim 3 characterized in that the ratio of displacements at the ends is 1.

7 - Bed according to any one of claims 1 to 2 characterized in that the frame comprises a diabolo (63) at an approximate end of the machine.

8 - Bed according to claim 2 characterized in that the arm comprises a roller (60) in its part close to the machine (1) to constitute a point of support of the arm when this arm is inserted (62) in this machine. 9 - Bed according to claim 3 characterized in that the machine and the frame have grooves (51,62) to receive the arm and in that the arm is provided with lateral pads (66,67) to guide it against the flanks of these gorges.

10 - Bed according to any one of claims 1 to 2 characterized in that the movable assembly comprises means (36) to offset the measurement of the position of the plate relative to the device.