Patent Publication Number: US-8110821-B2

Title: Shielded container structure for the transport and storage of a radioactive source for medical use

Description:
The present invention relates to a novel shielded container structure made of radioprotective material, for the transport and storage of a radioactive source for medical use. 
     In certain medical specialties and particularly cancerology, a definite dose of a suitable radioactive substance is sometimes administered to a patient for purpose of diagnosis or treatment. 
     To comply with the standards for safety and protection against radiation, these radioactive substances have to be transported and stored in shielded containers, interesting in that they protect against radiation any person who may come nearby, such as patients, hospital staff, or people in charge with the transport of these substances, etc. 
     Very generally, today&#39;s containers are made up of a shielded body made of radioprotective material, provided with an opening for the introduction and extraction of the bottle containing the radioactive source. 
     A shielded lid, also made of radioprotective material, is used to close the container and block the radiations passing through the opening. 
     In certain containers, the lid is merely put on the opening of the shielded body without any particular locking means, which is of course a possible source of incident. 
     That is why, in the majority of cases, the lid is held in place on the container body by locking means (in particular, by screwing). 
     However, present locking means are complex to implement; moreover, the operator is forced to firmly hold the container body to activate or deactivate the locking means when putting or removing the lid. 
     During these closing/opening operations, the person that handles the lid and the container body is finally subjected to radioactive radiation which can be not insignificant. 
     To remedy these drawbacks, the applicant has developed a container in which the lid can be locked very simply and very quickly onto the container body, without the operator being forced to hold this container body in a firm manner and for a long time. 
     In accordance with the invention, such locking means are shaped so as to be activated by a translational movement of the lid in the opening of the container body, this being termed the “locking movement” and taking place along the axis of said opening and towards the base element of the container, and said lid being further equipped with means for deactivating said locking means, in order to enable said shielded lid to be separated from said container body. 
     In one advantageous embodiment, the lid is provided with a plurality of retractable projecting studs designed to fit by a snap-action type phenomenon into at least one complementary housing formed in the opening of the container body. 
     These projecting lugs are operable between two positions:
     a locking position, in which they enter said housing by a snap-action type phenomenon during the locking translational movement, and   a retracted position, actuated by the deactivation means and in which they are located outside the bulk of said housing, enabling the shielded lid to be dissociated from the container body.
 
Moreover, said projecting studs cooperate on the one hand with spring means shaped so as to tend to keep the former in their locking position, and on the other hand with a deactivation member controllable by an operator to operate said projecting studs to their retracted position.
   

     In this embodiment, the studs are advantageously in the form of hooks hinged at one of their ends, and the other end of which projects inwardly so as to be able to cooperate with an annular groove opened outwardly and formed in the opening of the container body. The projecting hooks cooperate with the deactivation member that can be controlled by the operator so as to make the former pivot outwardly to the retracted position. 
     According to another characteristic, the deactivation member consists of one piece having an outwardly flared part forming a cam, said deactivation member being movable inside the lid between two positions:
     a rest position, in which the hooks are in the locking position, and   a deactivation position, obtained through an operator control action and in which said flared part pushes said hooks so as to make them pivot outwardly to the retracted position.   

     In this case, the lid is advantageously equipped with a handle whose operation by the operator ensures the displacement of the deactivation member so as to control the displacement of the protruding members between the unfolded and folded positions; alternatively, the deactivation member is operable to the deactivation position, corresponding to the retracted position of the hooks, through application by the operator of a magnetic field generated by means of a magnetic handle added on the lid. 
     Still in this case, the deactivation member is advantageously in the general form of a ring operable in an axial translational movement between the lower rest position and the upper deactivation position; said deactivation member being provided with an outwardly flared lower edge to form the operating cam acting on the hooks through pressing rollers, each of which is carried by one of said hooks, the latter being also connected to elastic return means in the form of a spring ring tending to keep them in the active locking position. 
     Still according to the invention, the container body is made up of a shielded inner part nested into an also-shielded outer part, these shielded parts being each made up of a belt of side walls connected to a base element. The inner part, on the side of the radioactive source, is made of radioprotective material having radioprotective characteristics higher than those of said outer part; the thickness of these inner and outer parts being a function of the required level of radioprotection. 
     In one advantageous embodiment, the container body comprises a tungsten inner part nested into a lead outer part; in this case, the closing lid locks onto the inner part, which has the advantage to be more resistant and less malleable than the lead. 
     According to an additional characteristic, the container body also comprises a peripheral shell made of a plastic material, covering the surface of the shielded outer part thereof. 
     Said plastic shell is advantageously made up of a belt of side walls, the lower edge of which is connected to a base element and the upper edge of which is extended by an upper return covering at least the upper edge of the shielded outer part; the base element and the lower edge of the belt of side walls of the plastic shell are provided with complementary structural means enabling them to be assembled by permanent or detachable nesting. 
     This plastic shell is interesting in that it is rather cheap, and thus able to be replaced when it is degraded; it also forms a protective envelop for the lead outer part of the container, the latter being relatively sensitive to physical attacks such as shocks or frictions. 
    
    
     
       The invention will be further illustrated, without being in any way limited, by the following description of two embodiments given only by way of example and shown in the attached drawings, in which: 
         FIG. 1  is a cross-sectional view of a container according to the invention, comprising a container body closed by a lid of the type which is unlockable by means of a magnetic handle; 
         FIGS. 2 and 3  are overall views of the closing lid of  FIG. 1 , with perspective views from below and from above, respectively; 
         FIG. 4  is a top view of the closing lid of  FIG. 1 to 3 ; 
         FIG. 5  is a broken sectional view along the cutting planes V-V of  FIG. 4 ; 
         FIG. 6  is a partial flat cross-sectional schematic view of the container of  FIG. 1 , in which the lid is shown just before being locked onto the shielded body; 
         FIG. 7  is another partial cross-sectional view of the container according to  FIGS. 1 and 6 , in which the locking means of the closing lid are operated to the deactivated position by means of a magnetic handle, to enable said lid to be separated from the shielded body; 
         FIG. 8  is a top view of another possible form of container, the closing lid of which is provided with a handle for an operator to operate the locking means thereof; 
         FIG. 9  is a broken sectional view of the container of  FIG. 8 , along the cutting planes IX-IX, and in which the closing lid is shown just before being locked onto the container body; 
         FIG. 10  is a partial view of the container of  FIG. 9 , in which the closing lid is locked onto the container body; 
         FIG. 11  is another partial view of the container of  FIG. 9 , in which the locking means are controlled to the retracted position by operation of the handle. 
     
    
    
     The shielded container  1 , shown in a schematic cross-sectional view in  FIG. 1 , is adapted for the transport of a receptacle  2  containing a radioactive substance, for example for a medical use. 
     The container  1  comprises a cylindrical body  3  made of radioprotective materials (namely, the association of a layer of tungsten with a layer of lead). The container body  3  is made up of a cylindrical side wall  3   a  connected to a flat base element  3   b ; the upper edge  3   c  of said cylindrical wall  3   a  defines a circular top opening  4  that, in  FIG. 1 , is closed by a closing lid  5  also made of radioprotective material. 
     In accordance with the invention and as described in detail hereinafter, the closing lid  5  comprises means for locking it to the container body  3 , shaped so as to be activated by a translational movement of the lid  5  in the opening  4 , this being termed the “locking movement” and taking place along the axis of said opening  4  and towards the opposing base element  3   b ; said lid  5  being further equipped with means for deactivating the locking means thereof in order to enable said shielded lid  5  to be separated from said container body  3  (still by a translational movement). 
     In this case, the closing lid  5 , shown isolated in  FIGS. 2 to 5 , is principally made of tungsten. 
     The lid  5  has a generally circular shape with a central axis  6 ; it comprises a main body  7  made up of a generally cylindrical lower part  7   a  and a generally tapered upper part  7   b , topped with a head  8  made up of a circular central part  8   a , the edge of which is extended by an annular skirt  8   b  extending opposite the main body  7  and remotely from the latter.
 
The lower part  7   a  of the main body  7  comprises an O-ring  7   c , intended to ensure the tightness of the lid  5  once it is locked onto the container body  3 .
 
     The lid  1  is equipped with means enabling it to be locked onto the container body  3 . 
     Said locking means are herein made up of four movable, hook-shaped struts  11 , regularly distributed in the space between the main body  7  and the opposing skirt  8   b.    
     Each of the locking hooks  11  is in the form of an elongated piece having two ends: 
     an upper end  11   a , carried by a ring  12  (visible in  FIG. 5 ), with a possibility of rotational movement about an axis  13  (perpendicular to the longitudinal axis  6  of the lid  5 ), and
     a lower end  11   b , having an inwardly projecting portion (i.e., herein, directed towards the longitudinal axis  6 ), intended to fit into a housing of the container body  3  to ensure the locking of the lid  5 .
 
Each of the hooks  11  also carries a pressing roller  14 , mounted so as to rotate freely around an axis  14   a  parallel to axis of rotation  13  of the former and intended to reduce the frictions during the operation of the hooks  11 .
   

     The locking hooks  11  are operable, around their axis of rotation  13 , between two positions:
     a locking position, corresponding to  FIGS. 1 and 5 , in which said hooks  11  are able to ensure the locking of the lid  5  onto the container body  3 , and   a retracted position, described in detail hereinafter with reference to  FIG. 7 , in which said hooks  11  are deactivated to enable the lid  5  to be separated from the container body  3 .   

     Elastic return means  15  are connected to the hooks  11  to tend to keep the latter in the locking position. 
     The return means  15  are herein in the general form of an elastic ring. 
     The operation of the hooks  11  from the locking position to the retracted position is performed by displacement of a movable piece  16 , called the “deactivation member”, equipping the lid  5  and controllable by the operator. 
     Such deactivation member  16  has the general form of a ring having an outwardly flared lower edge  16   a  and on which the roller  14  of the hooks  11  is kept pressed by the action of the elastic return means  15  of the latter. 
     The lower edge  16   a  of the deactivation member  16  forms a cam for operating the hooks  11  between their locking and unlocking positions. 
     To this end, the deactivation member  16  is operable in an axial translational movement inside the lid  5 , between two positions: 
     
         
         a lower, rest position ( FIGS. 1 and 5 ), maintained by elastic return means  17 , in which the rollers  14  of the hooks  11  cooperate with the small diameter of the lower edge  16   a  so that the hooks  11  are in the locking position, 
         an upper, deactivation position (described in detail hereinafter with reference to  FIG. 7 ), obtained by action of the operator, in which the great diameter portion of the lower edge  16   a  pushes the rollers  14  so as to make the hooks  11  pivot outwardly to the retracted position. 
       
    
     The elastic return means  17  can consist of spiral springs inserted in housings formed in the ring  16  and interposed between said ring and the lid head  8 . 
     Moreover, still in  FIG. 1 , it can be seen that the lid  5  is locked onto a particular structure of the container body  3 . 
     In this case, the upper edge  3   c  of the container  1  herein principally comprises an annular extension  20  having a generally triangular cross-section, with: 
     
         
         an outer inclined surface  20   a , in which is formed an annular groove  21  opened outwardly and shaped so as to receive the lower end  11   b  of the hooks  11 ; 
         an inner inclined surface  20   b , intended to conform the tapered part  7   b  of the closing lid  5 . 
       
    
     The operations of locking and unlocking the closing lid  5  with respect to the container body  3  will now be described with reference to  FIGS. 1 ,  6  and  7 . 
     First, with reference to  FIG. 6 , the locking process consists in suitably positioning the closing lid  5  opposite the opening  4 , so as it rests onto the upper edge  20 . 
     In this situation preceding the locking operation, it can be seen that the hooks  11  are in the locking position (as above-described with reference to  FIG. 5 ) and that the lower end  11   b  thereof rest onto the outer inclined surface  20   a  of the above-mentioned upper edge  20 . 
     Then, the operator applies a vertical pressure along the axis of the opening  4 , towards the base element  3   b  of the container body  3  (symbolized by the arrow  22  in  FIG. 6 ). 
     As the lid  5  moves along inside the opening  4 , the hooks  11  slide over the outer inclined surface  20   a , which make them pivot outwardly. Then, the hooks  11  are automatically returned to their original position by the elastic return means  15 , when their lower end  11   b  comes opposite the housing  21 ; this particular positioning displacement of the hooks  11  is a movement of the snap-action type. 
     The lid  5  is then suitably locked on the upper edge  3   c  of the container  3  and closes efficiently the opening  4  of the container body  3  ( FIG. 1 ). 
     In this position, the main part  7  and the skirt  8   b  of the lid  5  are positioned on each side of the extension  20  of the body  3 ; a chicane-shaped nest of these two elements is thus obtained, which further contributes to optimize the radioprotective efficiency of the container  1 . 
     To unlock the lid  5  ( FIG. 7 ), the operator uses a magnetic-field-emitting added means  24 , in the form of a magnetic handle for example, intended to permit controlling the above-described deactivation member  16  to its deactivation position. 
     To this end, in practice, the operator positions its magnetic handle  24  in contact with the surface of the lid  5 . 
     Once the handle  24  positioned, the magnetic field it emits makes the deactivation member  16  move upwardly to its upper position called “deactivation position”. Then, the lower edge  16   a  of the deactivation member  16  pushes the rollers  14  outwardly, which allows to make the associated hooks  11  move apart to the unlocking position. The magnetic handle  24 , attached by magnetization to the lid  5 , then enables the lid to be separated from to the container body  3 . 
     Of course, when the handle  24  is separated from the lid  5 , the deactivation member  16  is returned to its rest position by the elastic return means  17 ; the hooks  11  come back to the locking position under the action of the spring  15  associated thereto. 
     Thus, this container structure allows a simple, quick and efficient locking of the lid onto the container body. 
     Moreover, this container is interesting as far as the security is concerned, because the operator has to bring complementary means to be able to open the lid, which thus limits the risks of accidental opening. 
     The particular structure of the container body  3  can also be seen in  FIGS. 1 ,  6  and  7 . This body  3  is made up of a tungsten inner part  29  nested into a lead outer part  30 ; these two shielded parts are each made up of a belt of side walls connected to a base element. Thus, the inner part  29 , on the side of the radioactive source, is made of radioprotective material having radioprotective characteristics higher than those of the outer part  30 , the thickness of these inner  29  and outer  30  parts being a function of the required level of radioprotection. 
     The two parts  29  and  30  are herein maintained together by means of two cylindrical through-inserts  33  made of tungsten; the outer free end  33   a  of these inserts also serves for the fixation of the two free ends of transportation handle  34  of the container  1 , by suitable means. 
     The extension  20  of the container body, on which the closing lid  5  locks, is single-piece and constitutes a part of said tungsten lower part  29 . 
     The locking of the hooks  11  onto this lower part  29  enables the wear and friction resistance characteristics thereof to be used; this locking also allows a continuity of the tungsten shield, which further optimizes the obtained quality of protection against radiation. 
     Moreover, it is to be noticed that the lead shielded part  30  comprises an upper extension which surrounds the outer surface of the lid skirt  8   b.    
     To be complete, the body  3  further comprises a peripheral shell  31  made of a plastic material, covering the surface of the outer shielded part  30  thereof. 
     This plastic shell  31  is made up of a cylindrical wall  31   a , the lower edge of which is connected to a base element  31   b  and the upper edge of which is extended by an upper return  31   c  covering the upper edge or the outer shielded part  30 . 
     The base element  31   b  and the lower edge of the side wall  31   a  of the plastic shell  31  are provided with complementary structural means  32 , of the grooves/ribs type, enabling them to be assembled by nesting (which is permanent or detachable). 
     Said possibility of detachment can prove useful to facilitate the replacement of the outer shell when wore or damaged. 
     Generally, this particular structure of the container body  3 , combining a tungsten shield and a lead shield, can be used with a lid not having the above-mentioned particular locking means. 
       FIGS. 8 to 11  show another possible form of a container according to the invention, in which the closing lid is provided with locking means that can be deactivated by mechanical means, in this case a handle designed to this end. 
     This container  35  is similar to that above-described with reference to  FIGS. 1 to 7 . 
     The container body  3  is thus similar to that above-described. As for the lid  36 , it comprises the movable hooks  11 , each carrying a roller  14  and operable by the deactivation member  16 ; the only difference of the lid  36  with respect to the above one is that it is provided with a hinged handle  37  enabling the mechanical operation of the deactivation member  16 . 
     More precisely, the handle  37  supports a transversal pin  38  from which extend two vertical shafts  39  fixed to the deactivation member  16 . 
     It is herein the operation of the handle  37  that allows the displacement of the deactivation member  16  and the movement of the hooks  11  between the locking and unlocking positions. 
     In practice, for closing the body  3 , the handle  37  is pulled down onto the lid  36 , which corresponds to the lower rest position of the deactivation member  16  and to the locking position of the hooks  11  ( FIGS. 8 and 9 ). 
     Then, the lid  36  is positioned opposite the opening  4  of the container body  3  ( FIG. 9 ), and the operator pushes the lid  36  towards the base element  3   b  until the hooks  11  are snap-fitted into the housing  21  of the body  3  ( FIG. 10 ). The lid  36  is thus suitably locked onto the body  3 . 
     Conversely, to separate the lid  36  from the body  3 , the operator just has to operate the handle  37  upwardly, such as illustrated in  FIG. 11 . 
     During this operation, the transversal axis  38  moves upward, by the leverage generated by the two side extensions  40  resting on the upper face of the lid  36 , which implies an axial traction onto the vertical shafts  39 , the latter ensuring a movement of the deactivation member  16  to the upper deactivation position thereof. Finally, the hooks  11  end up to the unlocking position and dissociate from the housing  21 ; the operator can then separate the lid  36  from the container body  3 . 
     This latter embodiment has the advantage that it is relatively simple and do not necessitate the use of added means to unlock the lid  36 .