EP0316321A1

EP0316321A1 - Medical examination table for nmr or tomodensitometry

Info

Publication number: EP0316321A1
Application number: EP87904693A
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: JPH01503202A; FR2601580A1; WO1988000452A1

Abstract

Le lit d'examen comporte 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.The examination bed comprises 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 a. medical 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 supine position to non-invasive examinations with such machines.

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 machine's examination tunnel, and to illuminate and dialogue 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, it can happen to them to 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 off of lighting, ventilation, and monitoring means with anxiety. An intervention to extract the patient from the machine is then difficult because the motors for handling the plate 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 bring them back in their room when the exam is over. The beds are therefore removable from machines. This necessary constraint of mobility of the beds is poorly combined with the nature of the examinations undertaken. In fact, in these we produce images, seen in section, of parts of the

5 patient's body. 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 embro- chage the bed of the machine must match exactly _j n displacement means of the door panel patient on the bed with this panel movement means in the machine. To avoid this difficulty, we have imagined long panels, for example 3.50 meters, which always have one end meshed on the bed, the other end being inserted free in

U 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 aforementioned drawbacks by proposing beds, the plate and the drive means of which include means to facilitate the handling of the patient. On the one hand, the tray has been made removable to allow emergency withdrawals. This quality cannot be

25 conferred that with particularities of guiding the plate on its chassis and in the apparatus, particulars of offset setting in position of the plate relative to the apparatus, and these particularities being associated with a means of disengaging the plate from the means that ensure its movement. These means of

30 disengages allow an exact repositioning after the emergency intervention. In addition, the removable nature of the tray makes it possible to reduce the cost of the equipment to be built: it suffices to build a bed frame and several removable trays, placed in turn on the bed frame, to be able to be introduced into the machine. As a result, preparing patients for the exam no longer requires immobilizing the bed let alone the exam apparatus. On the other hand, the movement of the plate relative to the frame of the bed in order to be able to be introduced into the device is effected by means of an auxiliary arm, called a differential, of length close to the length of the plate and / or of the frame. (2 meters). One end of this arm drives the plate while the other rests on the chassis. This separates the tray function, actual patient support, from the mean function of moving the tray (over a distance greater than its useful length). As a result, the examination bed according to the invention regains a conventional length adapted to its conveying in hospital corridors.

The subject of the present invention is a medical examination bed, in particular for an NMR or computed tomography apparatus comprising a chassis, an examination plate, and drive means for moving the plate relative to its frame, and relative to the device characterized in that it comprises means for making the tray removable.

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 dif erential arm for maneuvering the platform;

- 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 tomodensitometer 1 is provided to receive, substantially along its axis Insertion 2, the body of a patient (not shown) supported by an examination bed 3 according to the invention. This examination Ut comprises a chassis 4, a plate 5, and drive means 6 for moving the plate relative to the chassis and relative to the device. The drive means 6 comprise a mobile device of elongated shape. This movable assembly comprises an arm 7, one end 8 of which is movable relative to the chassis and the other end of which 9 is movable 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 on the chassis with a length equal to the sum of the useful stroke 10 of the end 8 relative to the chassis and the useful stroke 11 of the end 9 relative to the plate. In addition, the arm has for ef and to offset the two extreme positions of the plate relative to the center of the frame. In the representation of Figure 1 the plate is in an extreme position suitable for -preparation for 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 _Q 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 takes 5 presses on a rack 16 secured to the chassis while the wheel

15 takes support 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, schematically represented by a cylinder 21, one can push on the end 8 of the arm 7. The rack 16 then turns the wheel, the latter drives the pinion 18 and, by means 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 relative to the chassis 4. The movement transformation ratio can be adapted by varying 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 equal to 1. The displacement 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 bolt 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 the space 24 to arrange the position of the patient's head on the plate 5, in particular when this head carries a part of the means of measurement 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

5 in the picture. 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 useful possible travel of the plate.

, Q to approach this platform as far as possible from the front of the machine.

What characterizes the invention is the presence in the plate 5 of means to make the plate removable. Schematically Figure 1 shows the plate 5 now a rack γ ^ drive 17 on which comes to mesh the moving element 6 to move the plate. The rack, held 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

20 the moving element escapes 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 a V such as 26 and 27, shafts support, respec¬ tively 28 and 29, of the rack 17. By simplifying the plate 25 25 is intended 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 longi¬ tudinal windows such as 32 of the plate 25 sliding along pawns 33 30 of the board 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 whose value is substantially equal to the useful length of movement of the plate 25 relative to the plate. 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.

FIGS. 2 to 4 show a particular example of the realization of the plate 5, of the movable assembly 6, and of the chassis 4. As an essential feature, the examination bed according to the invention should be supplemented with measurement means 36 of 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 space predetermined 24 of the apparatus 1, and as the plate is in the normal position for transporting the bed to 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 is any section of the pan in the machine when it is advanced there. This arrangement offers the advantage of allowing very tolerant positioning of the plate 5 in the machine. Ultimately, the 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 plate of trapezoidal cross section (FIG. 2), intended to slide on guides of corresponding shape in the apparatus and in the chassis (FIG. 4). The device 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 tray 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 tray 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 for longitudinally moving the two plates 25 and 52 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

10 rack is weak, that this one does not raise all alone under the effect of drive of the wheel 15. In an example rather than two sets 26-27 of cam-notches, the plates 25 and 52 comprise approximately one ten. This avoids having to overly stiffen the rack 17. i <> 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

20 box 7. The arm further has a front roller 60 to allow its support in the machine 1 when it is engaged. For this purpose the entry edge of the machine has a chamfer 61 (FIGS. 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 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 0 64 and 65 of the diabolo 63 authorize misalignments between the chassis 4 and the apparatus 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 supports 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 effort on the platform.

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 ba <= e 68 under the action of a motor 71. Under these conditions the gap 24 between the bed and the machine varies according to the height position of the bed in order to facilitate even more, in the low position, the passage of the operator. When it is raised, the bed undergoes a rotational movement to reduce the distance which separates it from the machine.

Claims

1 - Medical bed (3) for examination in particular for an apparatus (1) for NMR or computed tomography, comprising a chassis (4), a plate (5), motorized drive means (6) for moving the plate relative to its chassis and relative to the device, and

^ means (25,48-51) for disengaging the drive of the tray charac¬ terized in that the drive means comprise, in the tray, support means (17) for applying a force to the tray so as to move it in one direction and in that the means for disengaging the drive of the plate comprise means (25) 0 for retracting the support means.

2 - Bed according to claim 1, characterized in that the means for retracting the support means comprise means (V) for moving these supports orthogonally to the direction of movement of the plate. 5 3 - Bed according to any one of claims 1 to 2 characterized in that the plate has a trapezoidal profile (Fig, 2) to rest (37-40) by gravity independently of the drive means substantially in the center of its path displacement in the chassis and / or in the device. 0 4 - Bed according to any one of claims I to Z, characterized in that it comprises means for providing a gap (24) between the device and the head (23) of the bed tray.

5 - Bed according to any one of claims 1 to 2, characterized in that the means for retracting comprise a rack (17) horizontal movable perpendicular to its axis, and held at its side by the retracting means (25,32 , 33.53).

6 - Bed according to claim 5, characterized in that the means for retracting comprise at least one plate (25) provided with cams (26,27) to cause the displacement of the rack 0 when this plate is maneuvered, and at least one handle set

(30,34) fixed to the cam plate and to the plate to drive this movement. 7 - Bed according to any one of claims 1 to, characterized in that the means for moving comprise a movable assembly (6) relative to the plate and the chassis, of elongated shape (7), one end of which (8) is movable relative to the frame, and the other end (9) of which is movable relative to the plate.

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

9 - Bed according to claim 7 characterized in that it comprises means (18-20) so that the movements relative to the ends are mechanically dependent.

10 - Bed according to claim 9, 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.

11 - Bed according to claim 10, characterized in that the displacement means comprise a toothed belt (20) for meshing in pinions (18-19) of drive.

12 - Bed according to, claim 9 characterized in that the displacement ratio at the ends is equal to 1. 13 - Bed according to 10. claim 7 characterized in that the chassis comprises a diabolo (63) at an approximate end of the machine.

14 - Bed according to. claim 8 characterized in that the arm comprises a roller (60) in its part close to the machine (1) to constitute a point of support for the arm when this arm is inserted (62) in this machine.

15 - Bed according to 1 α. claim 8 characterized in that the machine and the chassis have grooves (51-62) for receiving the arm and in that the arm is provided with lateral shoes (66,67) to guide it against the sides of these grooves.

16 - Bed according to claim 7 characterized in that the mobile assembly comprises means (36) for shifting the measurement of the position of the plate relative to the device.

17 - Bed according to. 'claims 8 characterized in that the plate and the arm are made of non-magnetic and non-metallic materials.