Abstract:
A medical unit includes a shielded enclosure ( 2 ) in which are accommodated:—elements ( 13 ) for supporting a container ( 12 ) including a source or a generator of injectable radioactive product ( 11 ),—elements ( 10 ) for supporting a syringe ( 6 ),—a device ( 3 ) of the activimeter type, and—a system of pipes ( 9, 20, 23, 24 ) associated with at least one valve ( 15 ). The syringe support ( 10 ), the valve ( 15 ) and the radioactive source support ( 13 ) are arranged vertically relative to one another, respectively from top to bottom, the syringe support ( 10 ) being arranged to support the syringe ( 6 ) with the plunger ( 8 ) thereof oriented upward. The valve ( 15 ) and the syringe plunger ( 8 ) can be operated so as to ensure the withdrawal, dilution and injection operations.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the general field of nuclear medicine. More particularly, it relates to a medical unit utilized for withdrawal, calibration, dilution and/or injection of a radioactive substance intended for being injected to a patient. 
     2. Description of the Related Art 
     Some radioactive substances are particularly useful in the medical field, for example in imaging procedures, as contrast agents or as therapeutic agents. 
     In order to limit the doses of radiations received by the patient and by the personnel in charge of the manipulations, use is made of medical-use short half-life radioelements, namely radioactive products whose level of emitted radiation decreases rapidly with time. 
     But, with such short half-life radioactive products, it is problematic to administer a suitable dose to the patient. The corresponding dosage must be very precise; it must take into account the time necessary for preparing the dose to be injected as well as the possible time between the moment of preparation of the product dose and the moment of injection itself of this dose to the patient. 
     Further, despite the type of products implemented (short half-life), another constraint to be taken into account relates the radioprotection of the medical personnel in charge with the preparation of the radioactive dose and the injection of it to the patient. This radioprotection has also to be effective for the patient. 
     In a classical manner, the doses to be injected are withdrawn in a syringe provided with a suitable shielding and placed itself in a shielded enclosure equipped with suitable measuring and controlling means that enable the aimed dose of radioactive product to be withdrawn. Next, an operator picks up the shielded syringe and goes to the patient to make the injection. 
     However, this way of proceeding does not offer an optimal security, as far as both operator radioprotection and precision of the dose injected to the patient are concerned. 
     Document U.S. Pat. No. 6,767,319 describes an equipment for calibration and injection of a radioactive product, aiming to limit personnel exposure to the radioactive substance and also to optimize the patient security. 
     The corresponding installation comprises three separate radioprotective enclosures, each including:
         means for supporting a source of injectable radioactive product,   means for supporting a syringe, that are equipped with means for automatic operation of the plunger of the latter and that are associated with a device of the activimeter type for measuring in real time the radioisotopic activity from the product contained in the syringe, and   a system of valves.       

     This system of valves is hydraulically connected, through tubes, to the enclosure containing the radioactive mother source, to the enclosure containing the syringe, to a source of physiological saline solution and to an injection catheter intended for being connected to the patient. 
     This equipment further comprises means intended for driving the system of valves and the means for operating the syringe plunger, in such a way to ensure, in a first time, withdrawal of a dose of radioactive product and/or of physiological saline solution into the syringe, and in a second time, ejection of the withdrawn radioactive product and/or physiological saline solution through the injection catheter. The dose of radioactive product is measured by the activimeter device during withdrawal into the syringe. 
     In this equipment, the tubes that connect the enclosure containing the system of valves and those containing the syringe or the radioactive source are not protected and are sources of radioactive emissions into the environment. Moreover, because of the structure thereof, the corresponding equipment is cumbersome. Further, complexity of the network of tubes leads to the presence of significant dead volumes. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a novel very compact-size medical unit for calibration and injection of radioactive products, that allows withdrawal, measuring and injection of products with a great precision, in complete safety, and with reduced dead volumes. 
     This medical unit is of the type comprising:
         means for supporting a container made of a radioprotective material, in which is accommodated a source or a generator of injectable radioactive product,   means for supporting a syringe equipped with a plunger,   a device of the activimeter type for measuring in real time the radioisotopic activity from the contents of said syringe, and   a system of pipes associated with at least one valve for hydraulic connection of said radioactive source, of said syringe, of a source of physiological saline solution and of an injection catheter intended for being connected to the patient,
 
wherein said valve and said syringe plunger can be operated to ensure, on the one hand, aspiration of said radioactive product or said physiological saline solution into said syringe, and on the other hand, ejection, through said injection catheter, of said radioactive product, said physiological saline solution or a mixture of both, beforehand aspirated into said syringe, the dose of radioactive product withdrawn and injected by said syringe being measured by said activimeter.
       

     According to the invention, the medical unit further comprises a shielded enclosure made of at least one radioprotective material, in which are accommodated the radioactive source support, at least one part of the means for supporting the syringe, the activimeter, the valve and at least one part of the system of pipes. 
     Moreover, the syringe support, the valve and the radioactive source support are arranged vertically relative to one another, respectively from top to bottom, the syringe support being arranged to carry the syringe vertically with the plunger thereof oriented upward. 
     This particular arrangement enables the withdrawal/injection syringe and the radioactive product source to be close to the valve, which offers a very compact-size unit, with minimized dead volumes. 
     According to an embodiment feature, the valve consists in a three-way valve comprising:
         an upper way, intended for being connected to the withdrawal and injection syringe,   a lower way, intended for being connected to the source of injectable radioactive product, and   a side way, intended for being connected to a first pipe connected to the source of physiological saline solution and to a second pipe connected to the injection catheter, said pipes being each equipped with a suitably oriented check valve.       

     In this case, the activimeter has advantageously a generally tubular shape circumscribing a vertical-axis central well intended for containing the syringe, said activimeter being provided with two openings, an upper one and a lower one, the latter being directed opposite the three-way valve and the radioactive source support. 
     To reduce the dead volumes in the pipes of this equipment, the upper way of the valve, intended for being connected to the syringe, advantageously comprises a tight membrane seal intended for being pierced by the needle fitting said syringe mounted on the support thereof; likewise, the lower way of the valve, intended for being connected to the source of radioactive product is advantageously extended with a needle intended for piercing a membrane seal closing the vial that contains said radioactive source. 
     According to another embodiment feature of the invention, the radioactive source and syringe supports are each carried by means ensuring displacement(s) thereof along a vertical or substantially vertical axis, between two positions:
         a first position, in which an operator can install the radioactive source and the syringe onto the respective supports thereof, or inversely to remove them, and   a second position, in which the radioactive source and the syringe are connected to the valve.       

     According to this feature, the means for displacing the syringe support advantageously enable the later to travel vertically through an orifice arranged in the shielded closure, between:
         an upper installing/removing position, in which said support is located at least partially outside said enclosure, and   a lower connecting position, in which the syringe is positioned inside the central housing of the activimeter and is connected to the valve.       

     Moreover, the radioactive source support advantageously travels inside the shielded enclosure between the installing/removing and connecting positions thereof; this enclosure is further provided with a front trap door for enabling an operator to reach the radioactive source support at least when the latter is in the installing/removing position thereof. 
     According to still another feature, the medical unit comprises computer and/or electronic control means able to drive the valve and the means for operating the syringe plunger, in order for the withdrawal and ejection operations of the syringe to be performed. Likewise, the computer/electronic control means possibly also drive the means for displacing the syringe support and the radioactive source support. 
     In this case, the means for operating the syringe plunger are advantageously of the disengageable gear motor type, controlled by the computer/electronic means, to ensure, on the one hand, automatic withdrawal of a definite dose of radioactive product into the syringe, and on the other hand, injection of this dose to the patient, either automatically or manually. Indeed, the operator, if he or she wants, can disengage the gear motor means and manually control injection of the radioactive dose to the patient. 
     According to another interesting embodiment, the enclosure consists in three sub-enclosures aligned vertically relative to one another, namely:
         an upper sub-enclosure containing the syringe and the activimeter,   an intermediate sub-enclosure containing the valve, and   a lower sub-enclosure containing the source of radioactive product.
 
These sub-enclosures are connected together two by two via through-openings through which pass some of the hydraulic connecting pipes.
       

     To further optimize processing of the medical data, the computer/electronic control means are provided with connectics for sending and/or receiving data, in particular for exchanges with a computer server. 
     The medical unit according to the invention can be rendered mobile. To that end, it is mounted on advantageously motor-driven wheels; it possibly integrates a geolocation system, for example of the GPS type. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be further illustrated, without being in any way limited, by the following description of a particular embodiment, given only by way of example and shown in the attached drawings, in which: 
         FIG. 1  is a sectioned schematic view of a medical unit according to the invention; 
         FIG. 2  is a perspective view of the external structure of a possible embodiment of the medical unit illustrated in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in  FIG. 1 , the medical unit  1  according to the invention comprises a shielded enclosure  2  made of a radioprotective material, in which is located a device  3  for measuring in real time the radioisotopic activity (activimeter of the ACAD type (registered trademark)), that has a generally vertical-axis cylindrical shape and that is provided with an upper opening  4  and a lower opening  5 . 
     A conventional syringe  6 , comprising a body  7 , a plunger  8  and a needle  9 , is installed in the measuring well  3 ′ of the activimeter  3  (and is connected to a suitable processing unit); this syringe  6  is mounted vertically on an upper support  10 , with the plunger  8  thereof oriented upward and the needle  9  thereof thus oriented downward. 
     A source or generator  11  of radioactive product is placed under the activimeter  3 , opposite the lower opening  5  of the latter. This radioactive product source  11  is contained in a vial conditioned inside a shielded container  12  made of a radioprotective material. The shielded container  12  is accommodated in the shielded enclosure  2  and placed on a support  13 . 
     A motor-driven three-way valve  15 , accommodated in the shielded enclosure  2  between the syringe  6  and the vial of radioactive source  11 , ensures a suitable hydraulic connection between said syringe  6 , said vial of radioactive source  11 , a physiological saline solution bag  16  (external to the shielded enclosure  2 ) and an catheter  17  for injection to the patient (also external to the shielded enclosure  2 ). The valve  15  is located opposite the lower opening  5  of the activimeter  3  and opposite the radioactive source  11 . 
     The upper way  18  of this three-way valve  15  comprises a tight membrane seal intended for being pierced by the needle  9  of the syringe  6 . The lower way  19  of the valve  15  is extended with a needle  20  intended for piercing the tight membrane seal  21  closing the vial of radioactive source  11 . The side way  22  of the valve  15  is connected, through a Y-connector, to a tube  23  leading to the physiological saline solution bag  16  and to a tube  26  leading to the injection catheter  17 . The tube  23  is equipped with a check valve  25  preventing liquid returning toward the physiological saline solution bag  16 . The tube  24  is also equipped with a check valve  26  forcing the liquid to go toward the patient. 
     It can be seen in  FIG. 1  that the catheter  17  is also in communication with a second physiological saline solution bag  27 , through a tube  28  and a Y-connector  29 . 
     The three-way valve  15  has two main positions:—a first position, in which the upper  18  and lower  19  ways thereof are in communication (which enables the syringe  6  to be placed in communication with the radioactive product source  11  to ensure withdrawal of a dose of radioactive product into the syringe body  7 ), and—a second position, in which the upper  18  and side  22  ways are in communication (either to aspirate physiological saline solution from the bag  16  into the syringe body  7 , during an aspiration operation by the syringe  6 , or to eject the liquid contained in the syringe body  7  into the injection catheter  17 , through a draining operation of the syringe body  7 ). 
     A third possible position of the valve  15  consists in placing the radio-element source  11  and the tubes  23  and  24  in communication, so as to break the vacuum inside the vial of radioactive source  11  while allowing aspiration of the physiological saline solution from the bag  16 . 
     The three-way valve  15  is fixedly secured inside the enclosure  2 , on the vertical or substantially vertical axis running through the syringe  6  and the radioactive product source  11 . 
     The support  13  of the radioactive product source  11  is mobile in the vertical direction, according to the orienting arrow  30 , under the action of suitable mechanical means (not shown) actuated by hand (or by foot) or by motor means (not shown either), so as to enable introduction of the needle  20  into the vial of radioactive source  11  or extraction of this needle  20  from said vial. 
     The operator operates the mobile support  13  in this later “extracted” position when he or she wants to change the radioactive product source. 
     On the other hand, the support  10  of the syringe  6  is also mobile in the vertical direction, according to the orienting arrow  31 , under the action of suitable mechanical means (not shown) actuated by hand or by motor means (not shown either), so as to enable introduction of the needle  9  of the syringe  6  into the three-way valve  15  or extraction of the syringe  6  above the activimeter  3  and outside the shielded container  2 , for installation and removal of the syringe  6 . 
     The support  10  of the syringe  6  is further arranged to allow an operation of the syringe plunger  8  from the outside of the shielded container  2 , when said syringe  6  is centred in the measuring well  3 ′ of the activimeter  3 . 
     To that end, the support  10  comprises a cylindrical part  32  engaging with the rear part of the syringe body  7 , and a central part  33 , in the form of a plunger sliding into the cylindrical part  32 , engaging with the rear part of the syringe plunger  8 . 
     When the syringe body  7  is in position inside the measuring well  3 ′ of the activimeter  3 , the upper end of the sliding plunger  33  can be reached from the outside of the shielded container  2 . This plunger  33  upper end is associated with a disengageable motor system  34  which, once engaged, allows automatic operation of the syringe plunger  8  and which, when disengaged, allows manual operation of this plunger  8 . 
     This particularity enables the operator to choose between automatic and manual management of the radioactive product withdrawal by the syringe  6  and/or of the product ejection into the catheter  17 . 
     It can be noticed in  FIG. 1  that a solenoid pinch valve  35  is positioned in the tube  23  of the physiological saline solution bag  16 . The function of this solenoid valve  35  is to prevent untimely circulation of physiological saline solution through the tube  23  before connection of the injection catheter  17  to the patient. 
     It can also be noticed that two bubble preventing/antibacterial means  36 , for example in the form of filters, are present on the feeding tube  24  of the catheter  17  to ensure the sterility of the injection process. 
     Still in  FIG. 1 , it can be seen that the shielded enclosure  2  is in the form of three shielded sub-assemblies:
         a first assembly  2   a  integrates the activimeter  3  and a part of the syringe support  10 ,   a second assembly  2   b  encloses the motor-driven three-way valve  15 , and   a third assembly  2   c  encloses the mobile support  13  with the shielded container  12  thereof.       

     The three sub-enclosures  2   a ,  2   b  and  2   c  are stacked; the syringe  6  and the valve  15  are connected through an opening  37  arranged between said sub-assemblies  2   a  and  2   b . The valve  15  and the radioactive product source  11  are connected through an opening  38  arranged between the sub-assemblies  2   b  and  2   c.    
     The support  10  of the syringe  6  is made of a radioprotective material. The size thereof maximally fits in an opening  39  arranged in the upper part of the sub-assembly  2   a , to provide a shielding continuity in the lowered position (that is when the syringe  6  is centred in the measuring well  3 ′ of the activimeter  3 ). 
     The shielded enclosure  2  further comprises openings adapted for the tubes  23  and  24 , linked to the physiological saline solution bag  16  and to the catheter  17  respectively, to go through. 
     The main steps implemented in the medical unit  1  for preparation of a definite dose of radioactive product and then injection thereof to the patient will now be described in detail. 
     Firstly, the dose of radioactive product to be injected to the patient is prepared inside the syringe  6 . 
     To that end, the syringe  6  (with the plunger  8  thereof in low position) and the radioactive product source  11  are connected to the three-way valve  15 ; next, this valve  15  is driven so as to hydraulically connect the upper  18  and lower  19  ways thereof together, which enables the syringe needle  9  to communicate with the radioactive product source  11 . 
     The syringe plunger  8  is next operated, upward, to aspirate into the syringe body  7  the desired dose of radioactive product, which is measured in real time by the activimeter  3 . This dose is notably function of the patient&#39;s weight. 
     The dose prepared inside the syringe can next be administered to the patient. 
     To that end, the valve  15  is again driven so as to place the upper  18  and side  22  ways thereof in communication with the syringe needle  9  and with the tubes  23  and  24  (connected to the physiological saline solution bag  16  and to the injection catheter  17 ), respectively. 
     Before the injection phase itself, if necessary, the syringe plunger  8  can be driven (upward) to aspirate a complementary volume of physiological saline solution from the bag  16 ; this saline solution volume allows the radioactive product to be diluted and also a sufficient injection volume to be obtained. 
     Next, the syringe  6  is drained by a suitable displacement of the syringe plunger  8  (downward). The radioactive product, possibly diluted with the complementary volume of physiological saline solution, then travels through the tube  24  where it is filtered by the devices  36 , and then along the injection catheter  17  up to the patient. 
     Following this injection phase, the operator can possibly implement a complementary phase for rinsing the syringe body  7 , the valve  15  and downstream pipes  17  and  24 , with a volume of physiological saline solution suitable to ensure that the whole desired radioactive dose will be administered to the patient. 
     To that effect, the syringe plunger  8  is operated successively in aspiration (upward) to withdraw a definite volume of physiological saline solution from the bag  16 , and then in ejection (downward) to eject this volume through the pipe  24  and the ejection catheter  17 . 
     When the operator wants to replace the syringe  6  or the radioactive product source  11 , he or she just has to operate the respective support structures  10  and  13 . By way of information, the syringe  6  and the valve  15 , with the different ways thereof, can be replaced following each injection. The syringe  6  on the one hand, and the valve  15  with its needle  20  and pipes  23 ,  24 , the physiological saline solution bag  16  and the catheter  17  on the other hand, form a single-use sterile assembly that can be very easily replaced following each use. 
     The different afore-mentioned cycles of withdrawal, dilution and injection of this equipment are managed by computer and/or electronic control means, of the programmable controller type, able to drive automatically in a suitable manner the operating means  34  of the syringe plunger  8  and the three-way valve  15 . 
     Whole of these cycles can be fully automated. According to the needs, or the wishes of the operator, injection of the radioactive dose to the patient can also be performed manually thanks to the disengageable means of the gear motor  34 . 
     A particularly interesting form of the medical unit schematically illustrated in  FIG. 1  is shown in  FIG. 2 . 
     In  FIG. 2 , the shielded enclosure  2 , which integrates the whole above-mentioned functional equipment, is mounted on a frame equipped with four wheels  40 . Preferably, at least some of the wheels  40  are associated with a motor system providing a simple movement assist, or ensuring itself the autonomous moving of the mobile unit, remotely driven by a suitable joystick control unit. 
     The mobile unit  1  can also integrate a geolocation system, for example of the GPS type, so as to continuously know the remote location thereof inside a building. 
     It can be noticed the presence, in the lower part of the enclosure  2 , of a shielded trap door  41  providing access to the inside of the sub-enclosure  2   c , for installation or removal of the shielded container  12  enclosing the radioactive production source  11  on/from the support  13  thereof (in particular, when this support  13  is in low installing/removing position). 
     In the upper part, we can see the syringe support  10 , the physiological saline solution bag  16  hanging from a support  42 , as well as a touch-screen control and display board  43  that integrates the cycle management programmable controller or that is in direct relation with it (for example, being shifted in the unit frame). This control, dialogue and display board  43  allows the calibration operations (activity measurement) to be performed and the various phases of transfer preparation (dilution . . . ) and radioactive product injection to be viewed in real time. 
     The corresponding computer and/or electronic control means are equipped with connectics  44  for sending and/or receiving data, in particular for some exchanges with a computer server located at a nearby or a remote location (for example through an Intranet network or Internet), notably to perform a remote maintenance and to collect data concerning the patient (notably data necessary for determining the dose of radioelements that must be administered to him/her). 
     The frame of the unit  1  also carries its own power supply means, for example of the rechargeable battery type, ensuring the electric supplying, notably for the motor-driven wheels  40  and the computer and/or electronic control means. 
     This shielded mobile unit  1  forms a stand-alone unit enabling calibration and injection of any radioactive products (in particular, FDG). It is very compact-size because of the stacking of the activimeter, the three-way valve and the source of radioactive product on the same vertical axis or substantially on the same vertical axis, and because of the stacking of the sub-enclosures  2   a ,  2   b  and  2   c . This unit allows fully secure withdrawal, measuring and injection operations.