Abstract:
The pressure jacket systems of the invention are used to permit the front loading and removal of a syringe from an injector and include a first jacket segment and a second jacket segment surrounding the exterior surface of the syringe, interior surfaces comformable to the exterior surface of the syringe, a mechanism which allows movement of the first jacket segment in relation to the second jacket segment to permit insertion and removal of the syringe from the pressure jacket, and a mechanism for securing the first and second jacket segments in a fixed relationship upon insertion of the syringe.

Description:
TECHNICAL FIELD OF THE INVENTION  
         [0001]    This invention relates to pressure jacket systems for securing a syringe in an injector head. More specifically, the invention relates to pressure jacket systems which allow front loading and removal of a syringe, and which hold the syringe securely to an injector head during injection procedures.  
         BACKGROUND OF INVENTION  
         [0002]    In the medical field, patients often are injected with fluids in procedures such as angiography. In such procedures, which require controlled injection of a large volume of fluid into a patient, a needle is used as a conduit for the fluid which is connected to the syringe by a connector tube. The syringe is mounted on a motorized injector having an injector head.  
           [0003]    For long term compatibility with injectable fluids, syringes may be made of polypropylene with a minimum wall thickness. The thickness is critical as typical pressures of up to 1200 p.s.i. are used to inject the fluids into a patient. For safety and sanitary reasons, different disposable syringes are used for different fluids and different patients.  
           [0004]    Pressure jackets are known in the art for enclosing and retaining syringes while in use. A pressure jacket serves to limit radial expansion of a syringe which may lead to bursting or to leaks of the pressurized fluid around the seals of the syringe plunger. Another function of a pressure jacket is to prevent forward motion of the syringe. For example, typically a force of 2000 pounds is required to restrain the forward motion of a 200 ml syringe with a cross-section of 1.7 in 2  at 1200 p.s.i.  
           [0005]    Certain present pressure jackets are one piece designs, where the syringe is inserted into the jacket from the rear end of the jacket. An example of such a pressure jacket is found in U.S. Pat. No. 4,677,980, assigned to the common assignee of this application. The neck of the syringe protrudes from the front of the pressure jacket for connection of fluid lines which lead to the patient. Because the diameter of the syringe neck is much smaller than that of the syringe barrel, it can withstand both radial and forward force.  
           [0006]    However such an arrangement causes a problem when the syringe is removed from the pressure jacket. The neck of the syringe must pass through the present pressure jacket configurations. This requires the patient fluid path to be disconnected which presents a potential biohazard and may result in spilling fluids onto the pressure jacket. Additionally, fluid spilled during loading and purging air from the syringe may get inside the pressure jacket and require cleaning.  
           [0007]    Thus, a pressure jacket system is needed which permits a syringe to be front loaded onto an injector head and removed from the injector head without disconnecting the patient fluid path. Further, a pressure jacket system is needed which reduces the materials required for the manufacture of the syringe.  
         SUMMARY OF INVENTION  
         [0008]    The present invention relates to front loadable pressure jacket systems for use with injectors having an injector head with a housing and a front opening. A syringe is connected to the injector front opening to allow the flow of fluids through the syringe. A pressure jacket holds the syringe to the injector head. A piston extendible through the injector front opening imparts motive force to a plunger in the syringe to cause fluid flow.  
           [0009]    One embodiment of the present invention is a pressure jacket having first and second jacket halves each having interior surfaces conformable to the exterior surface of the syringe. A hinge pin extends from the front face of the injector head. The first and second jacket halves are rotatably mounted on the hinge pin. The halves may be placed in an open position allowing insertion and removal of the syringe or a closed position so that the jacket surrounds the syringe.  
           [0010]    A second embodiment of the present invention includes a pressure jacket with first and second jacket halves, where each jacket half has a front or distal end and a rear or proximal end. A hinge for rotational connection to the injector&#39;s front face allows the first and second jacket halves to be placed in an open position, allowing insertion and removal of the syringe, and a closed position such that the jacket substantially surrounds the syringe. A locking ring is disposed around the first and second jacket halves. The locking ring is placed in a position over the front ends of the first and second jacket halves when in the closed position and the ring is placed in a position near the proximal ends of the jacket halves when in the open position.  
           [0011]    A third embodiment of the present includes a pressure jacket which has a hollow cylinder portion with an open distal end and a rear end coupled to the injector head. The cylinder has at least one locking finger having front and rear ends, and a pivot axis disposed near the rear end. The pivot axis is connected to the open distal end of the cylinder. The locking finger is pivotable to a closed position such that the front end of the finger acts to hold the syringe within the cylinder. The finger is pivotable to an open position to allow the insertion or removal of the syringe.  
           [0012]    A fourth embodiment of the present invention includes a pressure jacket having a jacket cylinder with an open front end and a rear end coupled to the injector head. A first tie rod has a rear end attached to the injector head and a front end which is attached to a first front plate. The first front plate is pivotable between a closed position for holding the syringe within the jacket cylinder and an open position for allowing the insertion or removal of the syringe. A second tie rod likewise has a rear end attached to the injector head and a front end attached to a second front plate. The second front plate is pivotable between a closed position for holding the syringe within the jacket cylinder, and an open position for allowing the insertion or removal of the syringe.  
           [0013]    A fifth embodiment of the present invention includes a pressure jacket with a jacket cylinder having an open front end and a rear end coupled to the injector head. A first pivot is coupled to the injector head and a first tie rod is attached to the first pivot. A second pivot is coupled to the injector head and a second tie rod is attached to the second pivot. A front retaining plate joining the front ends of the tie rods allows the retaining plate to be pivotable between a closed position for holding the syringe within the jacket cylinder and an open position to allow the insertion or removal of the syringe from the jacket cylinder.  
           [0014]    A sixth embodiment of the present invention includes a pressure jacket which has a jacket cylinder formed around a longitudinal axis and having an open front end and a rear end. The jacket cylinder is transversely pivoted to the front face of the housing to allow the cylinder jacket to be pivoted between a closed position and an open position. An arm having a rear end affixed to the injector head is attached to a retaining member. The retaining member retains the syringe in the jacket cylinder when the jacket cylinder is in a closed position. The jacket permits the loading or removal of the syringe when the jacket cylinder is in an open position.  
           [0015]    A seventh embodiment of the present invention includes a pressure jacket which has a slidable canopy retractable within the injector head. An arm having a rear end is coupled to the injector head. The front end of the arm is coupled to a retaining member and retains the syringe. The canopy slides to a dosed position to retain the syringe and slides to an open position to allow the insertion or removal of the syringe. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a schematic view of an injector head and front loading syringe that may be used with the embodiments of the present invention;  
         [0017]    [0017]FIG. 2 is a perspective view of a first embodiment of the invention in an open position;  
         [0018]    [0018]FIG. 3 is a front elevational view of the first embodiment of the invention in an open position;  
         [0019]    [0019]FIG. 4 is a perspective view of the first embodiment of the present invention in a closed position;  
         [0020]    [0020]FIG. 5 is a front elevational view of the first embodiment of the present invention in a closed position;  
         [0021]    [0021]FIG. 6 is a perspective view of a second embodiment of the present invention in an open position;  
         [0022]    [0022]FIG. 7 is a perspective view of the second embodiment of the present invention in a closed position;  
         [0023]    [0023]FIG. 8 is an exploded view of a third embodiment of the present invention;  
         [0024]    [0024]FIG. 9A is an alternate configuration of the locking fingers of the third embodiment of the present invention in an open position;  
         [0025]    [0025]FIG. 9B is an alternate configuration of the locking fingers of FIG. 9A in a closed position;  
         [0026]    [0026]FIG. 10 is a front elevational view of a third embodiment of the present invention in an open position;  
         [0027]    [0027]FIG. 11 is a front elevational view of the third embodiment of the present invention in a closed position;  
         [0028]    [0028]FIG. 12 is a perspective view of a fourth embodiment of the present invention in an open position;  
         [0029]    [0029]FIG. 13 is a perspective view of the fourth embodiment of the present invention in a closed position;  
         [0030]    [0030]FIG. 14 is a perspective view of a fifth embodiment of the present invention in an open position;  
         [0031]    [0031]FIG. 15 is a perspective view of the fifth embodiment of the present invention in a closed position;  
         [0032]    [0032]FIG. 16 is a perspective view of a sixth embodiment of the present invention in an open position;  
         [0033]    [0033]FIG. 17A is a perspective view of the sixth embodiment of the present invention in a closed position;  
         [0034]    [0034]FIG. 17B is an isolated view of an alternative to the sixth embodiment of the present invention;  
         [0035]    [0035]FIG. 18 is a perspective view of a seventh embodiment of the present invention in a partially open position; and  
         [0036]    [0036]FIG. 19 is a front elevational view of the seventh embodiment of the present invention in a closed position. 
     
    
     DETAILED DESCRIPTION  
       [0037]    [0037]FIG. 1 shows an injector head indicated generally at  20  and a syringe  22  which may be used in connection with various embodiments of the present invention. The injector head  20  includes a housing  21  and a front face  23 . The injector head  20  is used to actuate syringe  22  which is mounted on the injector head  20 . The syringe  22  includes a tubular body  24  and a plunger  26  slidably positioned therein. In operation, the rear of the syringe  22  is fixed in or against an opening  30  on the injector front face  23 . Syringe  22  may be affixed to opening  30  by any suitable means, such as mounting flanges (not shown), as described in U.S. Pat. No. 5,383,858, assigned to the common assignee of this application and which is fully incorporated herein by reference. Any of the pressure jacket systems which are described below may be used to retain syringe  22  when syringe  22  is affixed to the injector front face  23 . The fluid within syringe  22  is pushed forward by a drive means, such as motorized piston  32 , extendable and retractable through opening  30 , which engages the rear surface  29  of plunger  26  to push plunger  26  forward in the syringe.  
         [0038]    FIGS.  2 - 3  show views of a first embodiment of the present invention in an open position and FIGS.  4 - 5  show views of the first embodiment in a closed position. Specifically, as shown in detail in FIG. 2, a fluid injector  40  includes a pressure jacket  42  which is of an axially split or “clam shell” type. The pressure jacket  42  is mounted to the front face  23  of the injector head  20 . When syringe  46  is installed into pressure jacket  42 , as more fully described below, motorized piston  32  when driven forward, engages a syringe plunger (not shown) and pushes the plunger forward in the body of a syringe  46  to force fluid out of the syringe tip  48 . Syringe  46 , preferably manufactured of a clear plastic, includes a body  50 , a neck  52  connected to the body  50  and a luer connector  54  connected to the neck  52 . A connector tube (not shown) may be connected to luer connector  54  which delivers fluid to the patient.  
         [0039]    As shown in FIGS.  2 - 3 , pressure jacket  42  which includes a first jacket half  56  and a second jacket half  58 , is preferably manufactured from a clear plastic so that the position of the plunger within installed syringe  46  may be observed. The first jacket half  56  and the second jacket half  58  have interior surfaces,  64  and  66 , respectively, which conform to the exterior surface of the body  50  of the syringe  46 . The first and second jacket halves  56  and  58  are joined by a pivot hinge  60  which allows the first jacket half  56  and the second jacket half  58  to be swung to an open position, as shown in FIGS. 2 and 3. Pivot hinge  60  has one end thereof affixed to the forward wall of injector head  20  at a point below injector head opening  30 , although in other embodiments the pivot hinge  60  may otherwise be radially displaced from opening  30 . For example, if it is desired that jacket halves  56  and  58  open to the side instead of from the top, the pivot hinge  60  would be positioned to one side of opening  30 . As shown in FIG. 2, the pivot hinge  60  is preferably parallel to axis A of the injector piston movement. With the pressure jacket  42  in the open position, syringe  46  may be inserted between the first jacket half  56  and the second jacket half  58 . The two jacket halves  56  and  58  are then closed and locked by means of a latch  62 , as shown in FIGS. 4 and 5, which in the illustrated embodiment is attached to first jacket half  56 . Alternately, one of the first or second jacket halves  56  or  58  may be fixed to the forward wall  23  of injector head  20  and the other jacket half may be pivotly mounted to the forward wall  23  of injector head  20 .  
         [0040]    As shown in FIGS.  2 - 5 , the first embodiment of the present invention allows front loading and removal of syringe  46  and any tubes attached thereto while minimizing fluid spills. Further, as syringe  46  is retained within pressure jacket  42 , the amount of material required to manufacture syringe  42  is reduced because the pressure jacket  42 , instead of the syringe walls, bears the majority of the pressure force exerted during a fluid injection procedure.  
         [0041]    A second embodiment of the present invention is shown in FIGS. 6 and 7. FIG. 6 shows a fluid injector  70  having a pressure jacket system  72  in an open position which permits the loading and removal of a syringe  76 . Pressure jacket  72 , a generally “alligator jaw” type, is hingedly affixed to an injector head  20  to which syringe  76  may be releasably installed. Specifically, as shown in FIG. 7, syringe  76  is held by a combination of a first or top jacket half  78  and a second or bottom jacket half  80 , together forming pressure jacket  72 , and a locking ring  82 . Both top jacket half  78  and bottom jacket half  80  are preferably made of clear plastic and have a semi-cylindrical shape. Interior semi-cylindrical surfaces  84  and  86  of top and bottom jacket halves  78  and  80 , respectively, conform to the exterior surface of the body of the syringe  76 . Jacket halves  78  and  80  have respective rear ends  88  and  90  located near the injector front face  23  and front ends  92  and  94  which coact to form an opening for the syringe neck  97 . The front ends  92  and  94  have interior surfaces which mate with the exterior conical transition region  96  of syringe  76 .  
         [0042]    When the top jacket half  78  and bottom jacket half  80  are in the closed position, as shown in FIG. 7, the locking ring  82  is placed about jacket halves  78  and  80 , preferably near the front ends  92  and  94  of jacket halves  78  and  80 . The top jacket half  78  is rotatable around a first hinge pin  98  while the bottom jacket half  80  is rotatable around a bottom hinge pin  100 . In order to open the pressure jacket  71  the locking ring  82  is moved along the length of the top jacket half  78  and bottom jacket half  80  to the injector front face  23 , as shown in FIG. 6. This allows the pressure jacket  72  to be opened by moving the top jacket half  78  about the first hinge pin  98  and moving the bottom jacket half  80  about the second hinge  100 . A link (not shown) between the two jacket halves  78  and  80  may be used to regulate the movement of the two halves so they move away and toward each other at the same rate. Alternatively, either the top or bottom jacket halves  78  or  80  may be fixed to the injector front face  23  while the other jacket half is pivotly mounted to the injector front face  23 . While in the open position, the syringe  76  may be inserted or removed from the pressure jacket  72 . The advantages relating to the first embodiment of the present invention, discussed above, are also realized with this second embodiment.  
         [0043]    FIGS.  8 - 11  show a third embodiment of the present invention. A fluid injector indicated generally at  110  includes a pressure jacket  112  with a plurality of locking fingers  114  for engaging a syringe  116 , shown in an open position in FIG. 10 and a closed position in FIG. 11. Pressure jacket  112  is connected at its rear end  132  to injector head  20  by any suitable means, such as a threaded connection (not shown). Syringe  116  has a cylindrical body  118  having a front end  120  and an open rear end  122 . The front end  120  of syringe  116  is tapered and connected to a neck  124 . A disk shaped drip flange  126  is formed around the neck  124 .  
         [0044]    The pressure jacket  112  includes a hollow cylinder  128  which is preferably made of clear plastic. A distal end  130  of the cylinder  128  is open to allow loading and removal of the syringe  116 . The distal end  130  of pressure jacket  112  has an outside surface  134  which is slightly smaller in diameter than that of cylinder  128 . The outside surface  134  of the distal end  130  is threaded (not shown). A plurality of locking fingers  114  (in the illustrative embodiment, six are shown) pivot about respective pivot points  136 , as shown in FIG. 10. Each locking finger  114  has a front end  131 , preferably beveled, and a rear end  133 . Pivot points  136  are located proximate to the rear ends  133  of the locking fingers  114  and are mounted within channels  138  located on the rim of distal end  130 . Locking fingers  114  may be kept in position by means of friction and are radially angularly spaced from each other on the rim of distal end  130 . It is understood that any number of locking fingers may be used.  
         [0045]    As shown in FIGS. 8, 10 and  11 , a locking ring  140 , generally cylindrical in shape, is threaded on its interior surface and threaded onto the outside surface  134  of the distal end  130  (threads not shown). The front end  142  of the locking ring  140  is a distal annulus extending radially inwardly to form an open orifice  144  which permits the syringe body  118  to be inserted into pressure jacket  112 , but does not permit the drip flange  126  to be inserted into pressure jacket  112 . FIG. 10 shows that the front interior surface of the front end  142  is sloped to engage locking fingers  114  when in a closed position, as shown in FIG. 11 and more fully described below.  
         [0046]    [0046]FIGS. 10 and 11 show that the syringe  116  is inserted into locking ring  140  and cylinder  128  so that drip flange  126  rests on the front end  142 . Locking ring  140  is screwed further onto cylinder  128 , and thus, moved toward the rear end  132  of cylinder  128 , as shown in FIG. 11. Locking fingers  114  are pivoted about there respective pivot points  136  from the open position of FIG. 10 to the closed position of FIG. 11 by the sloped interior surface of the locking ring  142  which engages the distal ends  133  of the locking fingers  114 . Front ends  131  of fingers  114  retain syringe  116  in place. When locking ring  140  is unscrewed away from the distal end  130  of the cylinder  128 , locking fingers  114  pivot into an open position. A spring member (not shown) may be used to bias the locking fingers  114  into the open position Syringe  116  may then be removed from or inserted into the pressure jacket  112 . The advantages relating to the first embodiment, as discussed above, are also realized by this embodiment.  
         [0047]    [0047]FIGS. 9A and 9B provide details of an alternative configuration of a locking finger. Specifically, the locking finger  314  of FIGS. 9A and 9B is an angled locking finger formed by an elongated base member  316  and retaining arm  318 , preferably integrally formed therewith. Base member  316  is pivotly mounted to cylinder  128  at pivot point  136 . The angel between base member  316  and arm  318  is similar to the angle of the taper of front end  120  of the syringe  116  to permit maximum retention of syringe  116  within pressure jacket  112 . As shown in FIG. 9A, syringe  16  may be removed from pressure jacket  112  by moving a screw threaded locking ring  340  toward pressure jacket rear end  132  on threaded surface  134  of cylinder  128 . Alternatively, as shown in FIG. 9B, syringe  116  may be held in pace by moving the locking ring  340  away from pressure jacket rear end  132  on threaded surface  134  of cylinder  128 . As locking fingers  314  are angled, retaining arms  318  serve as stops to prevent the anally outward motion of syringe  116 . Thus, locking ring  340  need not include a sloped inner surface, as described above.  
         [0048]    A fourth embodiment of the present invention is shown in FIGS. 12 and 13. FIG. 12 shows a fluid injection system indicated generally at  150  having a pressure jacket  152  of a split front plate type, in an open position, while FIG. 13 shows the pressure jacket  152  in a closed position. Similar to the third embodiment of the invention, the pressure jacket  152  includes a cylinder portion  164  which may be mounted at its proximal end  168  to the injector front face  23  by any suitable means, such as screw threads (not shown). A cylindrically-shaped syringe  154  including a neck  156  may be inserted into the distal end  166  of pressure jacket cylinder  164 . Syringe  154  further includes an alignment flange  158  comprising two diametrically opposed radially projecting wings  160  and  162  which aid in the alignment of the syringe  154  with resect to pressure jacket  152 . In a preferred embodiment, flange  158  is disposed in a plane including the axis of the syringe  154 .  
         [0049]    Syringe  154  is held in place by means of a combination of first and second front plates  170  and  172 . In a preferred embodiment, first and second front plates  170  and  172  are semi-circular in shape, such that each plate  170  and  172  has one straight margin and one arcuate margin. Plates  170  and  172  each contain semi-circular indentations  174  and  176  in their respective straight margins, and these indentations  174  and  176  form a neck access  178  for the neck  156  of the syringe  154 . The straight margins of front plates  170  and  172  act as flange slots  180  and  182  which conform to the wings  160  and  162  of syringe  154 . First front plate  170  has an end which is connected to a first tie rod  186 , which allows the first front plate  170  to be pivoted between an open position of FIG. 12 and a closed position of FIG. 13. Similarly, the second front plate  172  has an end which is attached to a second tie rod  184 , which allows the second front plate  172  to be pivoted between the open and closed positions.  
         [0050]    Tie rods  184  and  186  have proximal or rear ends which may simply be rotatably mounted to the injector front face  23 , or alternatively attached to gears (not shown) located in injector head  20  for automatic opening and closure. The tie rods  184  and  186  are preferably rigidly attached to the front plates  170  and  172 .  
         [0051]    When the pressure jacket  152  is in an open position as shown in FIG. 12, front plates  170  and  172  are pivoted away from the pressure jacket  152  by rotating the tie rods  184  and  186 . For example, sun and planetary gears (not shown) in the head  20  may provide symmetric rotation of the tie rods  184  and  186 . The open position allows the insertion or removal of syringe  154 . Once the syringe  154  is inserted within the jacket cylinder  164 , the front plates  170  and  172  are pivoted into the closed position as shown in FIG. 13. In this closed position front plates  170  and  172  extend across the front end  166  of jacket cylinder  164 . When front plates  170  and  172  are pivoted into the closed position, flange slots  180  and  182  act with the syringe flange wings  160  and  162  of the flange  158  to force the syringe  154  into proper angular alignment within pressure jacket  152 . In the illustrated embodiment, in proper alignment the syringe flange  158  is parallel to the plane formed by the tie rods  184  and  186 . The flange slots  180  and  182  in conjunction with the syringe flange  158  also act to prevent the syringe  154  from rotating during injector head operation.  
         [0052]    [0052]FIG. 12 also shows that front plates  170  and  172  include latches  192  and  194 , respectively, located at respective ends which are remote from or diametrically opposite from front plate pivot points  188  and  190 . Latches  192  and  194  clamp onto the distal ends of tie rods  184  and  186  respectively, and are operable to fix the front plates  170  and  172  in the closed position. Slots  196  and  198  are located near latches  192  and  194 , respectively, and are conformable to pivot points  188  and  190 , respectively, to permit a snug fit when front plates  170  and  172  are in a closed position. Front plates  170  and  172  may also include conical interior surfaces (not shown) which conform with the front of the syringe  154  when front plates are in a closed position.  
         [0053]    The advantages of the first embodiment discussed above are realized with this embodiment. Additionally, the use of flange slots  180  and  182  in conjunction with alignment flange  158  allows automatic alignment of the syringe  154  to an asymmetrical injector head drive means, such as a piston (not shown).  
         [0054]    An alternative to the above embodiment may be realized by making the tie rods  184  and  186  integral to the jacket cylinder  164 . A second alternative to the above embodiment may be realized by utilizing a syringe similar to that in FIG. 1 and eliminating the flange slots  180  and  182 , particularly if there is no need to automatically angularly align the syringe  154 .  
         [0055]    [0055]FIGS. 14 and 15 show a fifth embodiment of the present invention. FIG. 14 shows a fluid injector indicated generally at  210  having a pressure jacket  212  of a swing front retainer type in an open position FIG. 15 shows the pressure jacket  212  in a closed position. Like the other embodiments previously discussed, the pressure jacket  212  is mounted at its rear end  220  on the injector front face  23  by any suitable means. A syringe  214  inserted into the front end  218  of pressure jacket  212 , as shown in FIG. 15, includes a neck  226 . The syringe  214  is held in place against force exerted by the injector drive means on the syringe plunger (neither shown) by a front retaining plate  222  which has a slot  224  that allows the neck  226  of the syringe  214  to extend from the cylinder  216  through the front retaining plate  222 . The slot  224  is significantly smaller in a direction transverse to the longitudinal axis than the diameter of the syringe  214 , so that the remainder of the retaining plate may resist forward directed force placed on it by the syringe  214  during an injection operation. The slot  224  extends from the center of retaining plate  222  in a direction of the pivot of front plate  222  (discussed below) to the margin of plate  222 .  
         [0056]    In a preferred embodiment, the inside surface of slot  224  is contoured to engage the outside surface of syringe neck  226 . For example, if neck  226  is cylindrical in shape, the inside surface of slot  224  is cylindrical. If neck  226  is conical in shape, the inside surface of slot  224  is angled.  
         [0057]    An adapter  228 , which is an annular collar for tie rod connections, is mounted or integrally formed on the injector front face  23  and adjoins the pressure jacket cylinder  216 . The collar  228  has a pair of tie rod pins  230  and  232 . Bushings  234  and  236  rotate about tie rod pins  230  and  232 , forming pivots. Bushings  234  and  236  are connected to and may be integrally formed with to the rear ends of tie rods  238  and  240 . The front ends of tie rods  238  and  240  are connected to the front retaining plate  222 . It is understood that pins  230  and  232  may be located either on the injector front face  23  or on the exterior of jacket cylinder  216 .  
         [0058]    To open the pressure jacket  212 , the tie rods  238  and  240 , and front retaining plate  222  are pivoted about the pins  230  and  232  by bushings  234  and  236  which allow the syringe  214  to be inserted into the front end  218  of the jacket cylinder  216 . The front plate  222  and the rods  238  and  240  are then pivoted back into place to retain syringe  214 . It is understood that an alternative to this embodiment may include a front plate  222  formed by two halves each connected to a rod  238  and  240  such that each halve of the front plate  222  is pivoted into place to retain syringe  214 . The advantages relating to the first embodiment, as discussed above, are also realized by this embodiment.  
         [0059]    [0059]FIG. 16 shows a fluid injector indicated generally at  250  having a pressure jacket  252  of a “caulking gun” type. Like the embodiments already described, the pressure jacket  252 , when assembled, permits a piston (not shown) housed within an injector head  20  to apply forward force to a plunger (not shown) within a hollow body of a syringe  254 , thereby forcing fluid from a front connector end  256  thereof. The pressure jacket  252  has a jacket cylinder  258  which may be made of clear plastic. The jacket cylinder  258  may be rotated about pins  260  and  262  (the last shown in phantom) which are rotatably attached to the front face  264  of the injector head  20 . Front face  264  is curved or slanted which allows cylinder  258  to pivot about pins  260  and  262 . Cylinder  258  has an open front end  265  by which the syringe  254  may be loaded or removed.  
         [0060]    Attached to the injector head  20  is the rear end of an elongated arm  266  which is disposed in parallel to the longitudinal axis of syringe  254  when the latter is loaded into pressure jacket  252  and is ready for an injection operation. A retaining wall  268  is orthogonally attached to the front end of arm  266 . The retaining wall  268  has an internal surface  270  which is generally spherical or conical in shape so as to mate with an external spherical or conical surface of a syringe transition region  272  located between a syringe cylindrical body  274  and syringe tip  256 . Retaining wall  268  has an upwardly open slot  276  for the insertion of the neck  256  of the syringe  254  when the pressure jacket cylinder  258  is moved to a closed position, as shown in FIG. 17A. The slot  276  is cut in the same direction as the direction of articulation of the pivoting pressure jacket  252 .  
         [0061]    As shown in FIG. 16, cylinder  258  of pressure jacket  252  is pivoted to an open position to allow the loading or removal of the syringe  254  into the open end  265  of the cylinder  258 . The cylinder  258  is then pivoted back to rest against the arm  266  and the syringe neck  256  is lowered into the slot  276  of the retaining wall  268 . The advantages discussed above are also realized by this embodiment.  
         [0062]    [0062]FIG. 17B shows an alterative embodiment to that shown in FIG. 17A. A prong  277  attached to cylinder  258  is provided for engaging slot  276  of retaining wall  268  when the pressure jacket  252  is in the closed position so as to further secure syringe  254  within pressure jacket  252 .  
         [0063]    [0063]FIGS. 18 and 19 show the final embodiment of the present invention which is a fluid injector  280  having a pressure jacket  282  of a “slideable canopy” type for receiving and retaining a syringe  284 . The pressure jacket  282  has a canopy  286  which has an open front end  288  and an open rear end  290 . Canopy  286  is slidably mounted on the injector head  20 . An opening  292  in the front plate  293  of injector head  20  allows the canopy  286  to be retracted within the injector head  20 . Canopy  286  is preferably made of clear plastic. Alternatively, canopy  286  may telescope into or over a fixed tube which extends from injector head  20  (not shown).  
         [0064]    An arm  294  has a proximal or rear end mounted on the injector head  20 . The opposite, distal or front end of the arm  294  is orthogonally attached to a retaining wall  296  which has a slot  298  to allow placement of the neck  302  of the syringe  284 . In operation, the syringe  284  is placed on the arm  294  such that the neck  302  of syringe  284  is placed within the slot  298  of the retaining wall  296 . The retaining wall  296  has a conical shape to conform to the front of the syringe  284 . In order to hold the syringe  284  in place, the canopy  286  is moved along the arm  294  as by means of a channel  304 , as shown in FIG. 19, formed in the interior surface  306  of the canopy  286 . This arrangement allows the canopy  286  to slide on the arm  294  from an open to a closed position or vice versa, allowing the removal or insertion of syringe  284 . The advantages discussed above are also realized by this embodiment.  
         [0065]    The above described embodiments are merely illustrative of the principles of this invention. Other arrangements and advantages may be devised by those skilled in the art without departing from the spirit and scope of the invention. For example, the drip flange and other features described here may be used with other systems as well. Accordingly, the invention should be deemed not to be limited to the above detailed description but only by the spirit and scope of the claims which follow.