WO2004002314A2

WO2004002314A2 - Nuclear medicine machine with a protruding bed and use thereof

Info

Publication number: WO2004002314A2
Application number: PCT/EP2003/050255
Authority: WO
Inventors: Jean-Claude Geay
Original assignee: Sopha Medical Vision International
Priority date: 2002-06-26
Filing date: 2003-06-24
Publication date: 2004-01-08
Also published as: WO2004002314A3; FR2841456A1; FR2841456B1; AU2003255518A1; AU2003255518A8

Abstract

A nuclear medicine machine comprising a protruding bed, i.e. maintained on one of the ends thereof by a leg resting upon the ground. The leg can be moved along the ground and facilitates access to the machine, especially to change the sighting devices and the detectors thereof. In order to avoid the need for creating a patient door panel which is too rigid and therefore too heavy and too expensive, the machine is provided with a fixed effort take-up strut in a standby position at the other end of the examination tunnel. The principle underlying the use of said machine includes the provision of a bed which rests on the leg and said effort take-up strut, installation of the patient on the bed, and displacement of the bed in order to place zones of the patient's body such that they can be examined in front of the detectors.

Description

Cantilever bed nuclear medicine machine and its use

The present invention relates to a nuclear medicine machine with a cantilever examination bed, that is to say held by a foot located near an end of the bed. Such a bed is easily movable by hand, in particular to facilitate the use of the machine and its maintenance. The invention also relates to the use of this machine.

Nuclear medicine machines require the injection into the body of a patient of a radioactive isotope. The isotope is associated with a biological product which is metabolized in various selected places of the human body. At the time of this metabolism, the isotopes are fixed in the chosen organ and emit gamma rays. These gamma rays are captured by gamma ray detectors, preferably after being collimated. Among these gamma ray emissions certain emissions are particular. They relate to positron emissions for which two gamma photons are emitted in opposite directions from each other, simultaneously. We therefore know how to manufacture on the one hand conventional machines detecting gamma rays, and on the other hand so-called PET machines measuring the occurrence of these positrons. In both cases, by the number and distribution of sources of detected radiation, an image is created and the activity of the chosen organ is measured.

Nuclear medicine machines therefore have the particularity of offering images of radioelectric events which arise inside the human body. For this reason, they are also called transmitting machines.

For the acquisition of tomography images, in nuclear medicine as well as in tomodensitometry, it is known to acquire a series of images in projection, according to incidences offset from each other by a small difference. The smaller the difference, the better the resolution of the tomographic image. In practice, in order to be able to thus carry out acquisitions according to incidences varying progressively over at least 180 ° around the patient's body, a detector, or several detectors, is placed in a mobile device, rotating around the patient's body. The examination of the body of a patient is carried out in the following manner in such machines. The patient is placed, with an area to be examined of his body opposite the detection area of the nuclear medicine machine. While the patient is in this position, the machine acquires emission images for different incidences of the detectors around the patient's body. For example, the acquisition of images can take 20 seconds for each, and, by taking them with incidences offset by 5 °, we arrive at an examination duration of 12 minutes.

The gamma ray detectors of a nuclear medicine machine must therefore be carried by a structure, typically of the tunnel type, which allows these detectors to occupy around the patient's body all the desired incidences. The tunnel can be overturned, or it can be a virtual tunnel, that which is described by the detectors when rotating. Whatever the embodiment of the machine and its tunnel, there is a neutralized area at the location of this tunnel. This area is said to be neutralized because, when the patient settles down on the examination bed, it is not possible that a part of his body is simultaneously engaged in this area, in the tunnel. This prevents it from bumping or getting injured when it is installed. The length of the neutralized zone is equal to the length of the detectors increased by the length of a mechanical tunnel for supporting these detectors.

There are two types of examination beds that receive patients at the time of the examination. Either the examination beds have a patient support panel which translates onto a fixed support. Such a patient support panel corresponds to the length of a patient. In this case, this support is fixed to the machine. This support is longer than the panel. For example, the length of this support can be equal to the length of this panel increased by the length of the neutralized zone. Such an achievement has, in return for its advantages, many disadvantages.

On the one hand, the fact that the support is fixed makes it difficult to use the machine. In particular, changing the collimators mounted on the detectors is made difficult because of their weight. Access to the detectors by a collimator carrier trolley is therefore not facilitated due to the presence of this fixed support. On the other hand, the size of the support is important, which means that the machine cannot be used in medical offices which do not have a large examination room. A second type of examination bed relates to cantilever beds like those of the invention. In these, there is no fixed support. The patient support panel is as short as possible. It is directly attached to a movable leg by one of its ends. The bed with its foot moves on the floor to engage the other end of the panel in the machine. However, in this case, the bed should not undergo any deflection when a patient is placed there. This is only possible if its structure is very solid, therefore heavy and generally expensive.

In the invention, we want to use a cantilever bed to free access to the machine and in particular to be able to easily change the collimators. In order to then be able to produce a cantilever bed in light material, another solution has been provided. This solution consists in lengthening the bed, beyond the shortest possible length. In doing so, we reduce the handling, but only a little. There are then two problems to solve. On the one hand, we must avoid sagging. This is obtained by placing on the other side of the machine relative to the detectors, a force recovery mast. The end of the bed engaged in the machine is then led to the head of this mast. We thus pass from a cantilever structure to a conventional beam structure supported between two supports, but in which one of the two supports is fixed to the ground while the other secured to the bed is movable on the ground. We then have a bed comparable in performance to fixed beds with support. In particular, sufficient precision is obtained for adjusting the height of the bed in the machine, and therefore sufficient precision for producing the images, whatever the patient's weight. This precision is of the order of a tenth of a millimeter. We also obtain a lightness and maneuverability comparable to that of mobile cantilever beds.

On the other hand, we do not want the increase in length to penalize the maneuverability of the bed. Indeed, if the bed is too large, in small examination rooms it will not be easy to maneuver it. By way of improvement, with the invention, a longer bed is then provided than the short and solid bed criticized, but less long than the fixed bed. In this improvement, the length is increased by a fraction of the length of the neutralized zone. Typically the length of such a bed according to the invention corresponds to the length of a patient, increased by a length equal to the length of the field of the detectors. We then place at the head of the mast of recovery of effort a recovery arm. This recovery arm extends in the machine, through the mechanical tunnel of the machine, from this force recovery mast, to a limit where it would interpose in this field of detectors. When the bed is introduced into the machine, this recovery arm receives the end of the bed, before the patient lies down on it. Then it is put in place. The recovery arm then gives way a little under the weight, but not too much. Its rigidity is sufficient for a chamfer in the end of the bed, or a slope at the edge of a receiving wheel at the top of the mast, to then place the underside of the bed on the top of the mast, when the area to be examined of the patient arrives opposite the detectors. The height of the top of the mast is controlled like the height of the foot. In this way the expected precision is obtained.

The invention therefore relates to a nuclear medicine machine comprising a set of scintigraphy detectors, a mechanical tunnel provided with a ring for holding these detectors at a first end of the mechanical tunnel, this ring being movable in rotation, a bed examination in longitudinal overhang provided at a first end with a movable foot and engaging, due to the mobility of this movable foot, in the field of detectors by a second end opposite the first end, characterized in that it comprises a force recovery mast arranged at another end of the mechanical tunnel to receive the second end of the bed.

The invention also relates to the use of such a nuclear medicine machine, characterized in that the following is carried out in order: - the positioning of the bed with its second end in abutment on the recovery mast,

- placing the patient on the bed, and

- moving the bed to put the areas of the patient's body to be examined by the detectors. The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These are presented for information only and in no way limit the invention. The figures show:

- Figures 1a and 1b: side views of the machine of the invention, for two positions of the bed relative to this machine, respectively a first position where the patient settles on the bed and a second position where the bed is advanced as far as possible in the machine for the examination;

- Figure 2: A top view of two positions of the foot of the bed corresponding to the positions of Figures 1a and 1b.

Figures 1a and 1b show a nuclear medicine machine according to the invention. In the example, this machine includes a set of two scintigraphy detectors 1 and 2. The game could have more than two detectors if necessary. It could just as easily have only one. In the example, the two detectors are oriented with their normals 3 and 4 respectively at their detection field perpendicular to each other. However, these normals 3 and 4 could be inclined to one another with a different angle. As a variant, the two normal could even be collinear, the two detectors facing each other to constitute in particular a machine of the PET type. The two detectors 1 and 2 are provided with a collimator such as 5, for example fixed by fasteners 6 and which it is necessary to change to practice an examination of a particular type. These collimators being heavy, it is advisable to release an access to these detectors.

The detectors 1 and 2 are carried in the machine by a ring 7 for holding these detectors. The crown 7, or an equivalent device, is movable in rotation about an axis 8. The axis 8 is normally supposed to pass through the middle of the body of a patient, or more exactly through the middle of an area to be examined. of this patient’s body. For this purpose, as will be seen below, the crown 7 and or a bed 9 for supporting a patient 10 can be lowered and or respectively raised in height so as to obtain this coincidence. The crown 7 is carried by a frame 11 resting on the ground by means of a base 12.

In the example shown, the machine has only one crown 7 and the detectors 1 and 2 are cantilevered relative to the frame 11. However, it would be possible to provide a second crown, on the other side detectors 1 and 2 relative to the crown 7, as well as a second symmetrical frame of the frame 1 1. An examination tunnel is formed in the machine firstly by a space in the frame 1 1 (and in the symmetrical frame s 'there are) as well as secondly in a space occupied by the detectors 1 and 2 when these rotate around the axis 8. This second space can be covered or not depending on the type of machine. The tunnel area is a neutralized area. FIG. 1 b shows more precisely the examination bed 9 in overhang. This bed 9 essentially comprises a single foot 13 located near an end 14 of the bed. The end 14 is one end of the bed opposite to one end 15 of the bed by which the bed enters the space between the detectors 1 and 2. The bed 9 is held in cantilever by a horizontal rigid support 15. A particularity of the cantilever bed 9 is that the end 14 cannot be moved, along the axis 8, relative to the support 15. Any advance of the bed to present the different parts of the patient's body 10, opposite detectors 1 and 2 is obtained by a movement of the foot 13 on the ground. For example, this foot 13 is guided, and braced, on a guide 16 on which it slides, for example by means of a ball bushing. The bed 9 moreover comprises a rolling device 18 making it possible to move on the ground by driving the guide 16. At another end of the guide 16, another rolling device 19 can be produced. Or else the device 19 is a pivot which can be formed in the ground, between legs of the base 12 so that the bed can pivot around a vertical axis 20.

The bed of the invention thus comprises only one mobile retaining mast 13. FIG. 1a shows figuratively two masts 13 and 13 '. However, in fact it is 13 'of the same mast 13 occupying the position of FIG. 1 b. FIG. 1a as well as FIG. 1b show exploration ribs of 4.072 meters as well as a nominal longitudinal displacement of 1.523 meters from the foot 13 of the bed, and a construction distance of 2.380 meters to place the bed correctly in an exam room.

An essential characteristic of the invention lies in the fact that the machine comprises a force recovery mast 21. The mast 21 is disposed at another end of the mechanical tunnel than that through which the bed 9 is introduced. By doing so, we have all the qualities of the various known beds. On the one hand the bed 9 is movable on the ground as we have seen, and therefore allows simple access to the detectors 1 and 2 to change the collimators 5. On the other hand, the presence of the recovery mast 21 allows rigorously and precisely control the height position of the body 10 relative to the axis 8. Because of the presence of the recovery mast 21, a patient support panel 22 does not need to be as rigid, too solid, than a known panel of a cantilever bed. In particular in the invention, for reasons of weight and cost, the patient support panel 22 can be made of wood, a laminated or glued structure or plywood. Wood also has all the qualities necessary to let gamma rays pass through without attenuating them. The fact of also making the wooden panel at the same time makes handling of the bed 9 much easier and allows the manipulators to be manipulators.

The recovery mast 21 as the foot 3 is adjustable in height. To this end, they each comprise a jack system, preferably electric. The cylinders are servo-controlled to be by construction both at the same height. Such an embodiment is already accessible in known machines with a fixed support bed.

The realization of such a motorization requires on the other hand, because of its thickness, that the mast 21 cannot be located at the location of the crown 7 nor at the location of the frame 11. Therefore, the mast 21 is located at the end of the frame 11, on the other side of this frame 11 relative to the direction of entry of the bed 9. This can have two consequences. Firstly, the length of the patient-carrying panel 22 may have to be increased so that when the patient 10 settles there, the end 15 is already in abutment on a support zone 23 of the mast 21. This arrangement, which is possible, however slightly reduces the maneuverability of the bed. The bed of the invention retains its advantages but to a lesser degree than what could be obtained with further improvement.

This additional improvement includes the production at the top of the mast 21 of a recovery arm 24. The arm 21 is cantilevered from the mast 21 in the direction of the detectors 1 and 2. Preferably the length of the extension of the arm 24 is limited by the position of the crown 7, so that one end 25 of the arm 24 does not interfere in the detection field of the detectors 1 and 2. In all cases, the length of the arm 24 has as a consequence the reduction of the useful length of the panel 22 to a length equal to the length of the patient 10 increased by the detection length of the detectors 1 and 2 measured along the axis 8. It is no longer necessary that this length be plus the length needed to cross the frame 11 and then arrive on the support 23. The arm 24, which can be removable and be a removable accessory, is not necessarily very rigid (and therefore heavy) The use of the bed of the invention is as follows. The bed 9, when empty, is brought into the machine, for example in the low position so that the patient can later settle there. The bed 9 is approached in such a way that its end 15 rests on the end 25 of the arm 24, or if the improvement is not retained, its end 15 rests above the support zone 23. When this position is reached, patient 10 settles down. We note that, whatever its position (here its head is far from detectors 1 and 2), none of the parts of its body, needs to penetrate the tunnel, real or virtual, formed by the space located between the detectors 1 and 2. There is therefore no risk of injury. Once the patient is in position, as indicated in FIG. 1 a, the bed 9 is advanced in the machine to place the part of the patient's body to be examined with regard to the detectors 1 and 2.

In practice, at the moment when the patient 10 places himself on the panel 22, the arm 24 slightly bends because he has chosen for him a structure which is not too rigid, not too heavy either. We choose to limit this deflection to a value such that it allows the panel 22 to then pass normally over the support 23. This normal passage can be obtained in different ways. In one example, the arm 24 has a hypercambered position at rest (without the patient being placed on it) so as to guide the panel 22 clearly above the support 23. Or, the end 15 of the bed 9 has a chamfer making it possible to compensate for sagging by a vertical displacement resulting from the longitudinal displacement of the panel 22, and to cause the panel 22 to rise on the support 23. Or, the support 23 is itself provided with a reception wheel allowing an elevation and therefore a repacking at the correct height of the panel 22 at the time of the introduction of the bed with regard to the detectors 1 and 2. The three solutions can be used in combination.

Once the patient is placed on the panel 22, this panel can be mounted at the desired height by acting simultaneously on the jacks of the masts 13 and 21

Figure 2 shows the appearance of a pedestal 26 which supports the mast 13 of the bed 9. This pedestal 26 comprises a transverse beam 27 and a strut 28 both connected by ball bushings to a rigid shaft 16. L 'shaft 16 is held horizontally above the ground by a base plate 29 and end consoles. At one end of the beam 27, opposite to that where the sliding bushing is located on the shaft 16, the rolling device 18 is placed. In one example, this rolling device can be replaced by a device for moving on a cushion d 'air. In the upper part, at the top of the mast 13, the bed 9 comprises a support 15 having a lateral, horizontal extension, and perpendicular to the axis 8, allowing the panel 22 to move laterally. Figure 2 shows the two positions of the pedestal 26 corresponding to Figures 1a, remote position, and 1b, position of the body introduced into the machine.

Claims

1 - Nuclear medicine machine comprising a set of scintigraphy detectors, a mechanical tunnel provided with a ring for holding these detectors at a first end of the mechanical tunnel, this ring being movable in rotation, an examination bed in carrier longitudinal overhang provided at a first end with a movable leg and engaging, due to the mobility of this movable leg, in the field of detectors by a second end opposite the first end, characterized in that it includes a force recovery mast arranged at another end of the mechanical tunnel to receive the second end of the bed.

2 - Machine according to claim 1, characterized in that the recovery mast comprises a force recovery arm which extends in the mechanical tunnel towards the first end of the tunnel. 3 - Machine according to claim 2, characterized in that the recovery arm extends in the mechanical tunnel to a limit where it would interpose in this field of detectors

4 - Machine according to one of claims 1 to 3, characterized in that the recovery mast and or the patient door panel have means to compensate for a deflection of the bed before engagement of this bed at the top of the recovery mast.

5 - Use of a nuclear medicine machine according to one of claims 1 to 4, characterized in that one carries out in order:

- placing the bed with its second end resting on the recovery mast,

- placing the patient on the bed, and

- moving the bed to put the areas of the patient's body to be examined by the detectors.

6 - Use according to claim 5, characterized in that in the first step the bed is placed with its second end in abutment on a recovery arm held by the recovery mast.