Patent Number: 042008042
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1 and 2 illustrate the system of an embodiment of the invention with FIG. 1 showing the system in assembled form and ready for packaging or storage. To facilitate understanding of the invention, reference is first made to FIGS. 3-5 which illustrate the shielded syringe portion of the invention. The core of the shielded syringe includes the basic elements of a conventional disposable-type plastic syringe, as labeled in the drawings by reference numeral 110. The syringe 110 has a plastic body or barrel 111, a rear flange 112, a plunger 113 and a tip 114. The plunger 113 has a conventional head or tip 117, typically formed of rubber, which is coupled to a plunger stem 118 by a novel shielding plug 119. The plug 119 is formed of a high density radiation-shielding material, such as lead or tantalum or plated lead. The plug has a cylindrical central portion which conforms generally to the inner circumference of the barrel 111, a front retaining nub 119A which is inserted in an aperture in the rear of tip 117, and a rear retaining nub 119B which snaps into and seats in the front end of the plunger stem 118. The plug 119 serves to shield the operator using the device against radiation emitted axially from the rear of the barrel. This radiation, which would typically and dangerously be directed toward the body of the operator, is generally not satisfactorily shielded in the prior art. The syringe body has volumetric indicia disposed in a longitudinal pattern along its barrel as shown at 115. A generally cylindrical body 130 is formed of a radiation-shielding material, such as lead, and is proportioned such that its inner surface conforms generally to the outer surface of the syringe barrel 111. The body 130 tapers inwardly at its front end at 138 and has an elongated rectangular slot 139 extending along one side thereof, the slot being in registration with the indicia 15 on the barrel 111. The surface containing the slot is flat on top and a pair of panels 131 and 132, which can be formed integrally of the same radiation-shielding material such as lead, are spaced slightly from the parallel edges of the slot and extend outwardly from the flat surface. A transparent radiation-shielding member 140 is of elongated rectangular shape and may be formed of leaded glass typically having a thickness which is substantially greater than that of the body 130. The member 140 is encased in a rectangular casing 141 which is opened at the top and bottom thereof. Pairs of lips 142 and 143 retain the member 140 within the casing 141. The top edge of the casing slants upward at the front thereof as shown at 145 so that the front end protrudes slightly above the top of the encased member 140. In the present embodiment the casing 141 is formed of material such as rigid plastic and the member 140 is snapped into the casing 141 for permanent retention therein and reuse in a manner to be described. The casing is proportioned to slideably fit within the panels 131 and 132 of body 130 such that the transparent shielding member 140 overlays the periphery of the slot 139 in body 130. As will be described, the encased member 140 is typically inserted in the shielded syringe at the time when it is to be used to inject a patient. A shell 150 is preferably formed of rigid plastic and is proportioned to generally conform in shape to the outer surface of the body 130. Specifically, the shell 150 has a pair of side panels 151 and 152 which cover and extend above the body panels 131 and 132, respectively. The panels 151 and 152 have lips 153 and 154, respectively, which define an elongated slot that is in registration with the slot 139 in body 130. The front end of the shell 150 is about half opened and has an approximately semicircular wall 156 having a circular aperture therein which receives the tip 114 of the syringe 110. The tip 114 is provided with an annular groove which is retained in the aperture as seen in FIG. 4. A cylindrical shroud 157 extends axially from the wall 156 and protrudes slightly above the top edge of the wall. The shroud 157, which may typically be formed integrally with the body, has an annular protrusion at 158. To assemble the disposable portion of the device described thus far, the syringe 110, with its plunger in place, is inserted into the body 130. The syringe flange 112 has a wall member 112A formed on the inner surface thereof which serves as a spacer between the rear end of the body 130 and the flange. The syringe and body are then inserted into the open-ended rear of the shell. The rear edge of the shell fits over the periphery of wall 119 and is secured to the flange 112 by any suitable means, such as an epoxy bond. This assembly comprises the portion of the shielded syringe which is most suitable for disposability. FIG. 4 also shows the manner in which a standard needle can be mounted over the syringe tip and is conveniently retained within the shroud 157 by the annular protrusion 158. This eliminates the need for screwing in the needle and facilitates more convenient operation. However, it will be understood that a standard needle mounting, such as a Luer-lock mounting, can be employed. In accordance with the invention, an aliquot of radioisotope-containing fluid is loaded into the syringe barrel before packaging. In the embodiment of FIGS. 1 and 2, a multipurpose sub-assembly is provided to deal with the presence of the radioisotope fluid. A radiation-shielding unit 210 includes a cover 210 which is proportioned at least large enough to cover the slot 139 (FIG. 5). In the present embodiment, a flange 212 extends downwardly from the front edge of the cover 211 and is formed integrally therewith. A hollow shroud 213, having a closed front end, protrudes from the flange at a position thereon which is in registration with the position of the tip 114 of the syringe. The rear end of the cover 211 has a reduced thickness, as shown, to fit over the flange 112. A protruding rear handle 215 has an indented neck portion 216 which extends from the rear edge of the cover 211. In the present embodiment, the shielding unit 210, including the cover 211, the front flange 212, the shroud 213 and the necked handle 215 are integrally formed of a single piece of radiation-shielding material, such as lead. The lead may be plastic coated or plated, if desired. The embodiment of FIGS. 1 and 2 further includes a horseshoe-shaped clip 230 which may be formed of any suitable material, but is preferably formed of plastic. The plunger stem 118 has a pair of slots in opposite sides of one of its cross panels, as depicted in dotted line in FIG. 2 (the stem itself being shown in dashed line). The slots are referred to by reference numerals 118A and 118B. The clip 230 is proportioned to engage the slots 118A and 118B when the plunger 110 is in its fully extended position. The spaced ends 231 and 232 of the clip are proportioned to engage the neck 216 of the rear handle of shielding unit 210 when the unit is positioned in place over the slot 139 (see dashed line depiction in FIG. 2). Operation of the invention is as follows: at the packaging facility, the aliquot of radioisotope is indroduced into the barrel 111 of syringe 110. The shielding unit 210 is positioned over the slot in the syringe shielding body with the shroud 213 covering the protruding tip of the syringe. The clip 230 is then engaged with the slots in the plunger stem, the ends of the clip engaging the neck portion of the rear handle 215 of unit 210. Depressions 231A and 232A are provided in the clip, and a retaining wire is wrapped around the depressed regions. The clip is formed of a material, such as plastic, which is sufficiently flexible to yield slightly to engage the plunger and cover unit. The overall system is typically stored in a carton for transporting. It is seen that the clip serves to retain the plunger in the fully extended position to prevent accidental depression thereof during shipping. The clip also retains the shielding unit 210 in place. The shielding unit, in conjunction with the disposable shielded syringe, is seen to render the radioisotope material completely shielded, the cover 211 providing shielding above the aperture, and the front flange and shroud providing shielding forwardly of the syringe body. The shielding plug 119 (FIG. 4) provides shielding in the rear axial direction. When the assembly is to be used, it is removed from its carton and the wire 250 and clip 230 are removed. This serves to release the plunger 110 for subsequent activation and also to release the shielding unit 210 which can now be removed. If desired, the reusable optically-transparent radiation-shielding member 140 (FIGS. 3-5, and in dashed line in FIG. 2) can now be inserted over the slot 139 to provide shielding during usage while still allowing the operator to view the contents of the shielded syringe. In the present embodiment, the encased transparent shielding member 140 is inserted in the shell through the front opening therein and is retained from sliding out during use by the protruding portion of the shroud 157. If desired, an assay can be performed prior to insertion of the leaded glass shielding member. After injection of the unit dose of radioisotope into the patient, the leaded glass shielding member 140 is removed for use in conjunction with other disposable systems, and the remainder of the system can be discarded (removal being facilitated by the raised edge of the casing (145) which can be grasped such as by using the thumb and finger). Thus, virtually complete shielding is provided from the time of packaging until use, handling of radioisotope materials is eliminated, and the inconvenience of handling shielding media and of measuring are all eliminated. The portion of the system which is disposable is relatively inexpensive to manufacture and the relatively expensive leaded-glass is reusable. In addition to the advantages in safety and convenience, the need to clean contaminated shields is eliminated. The invention has been described with reference to a particular embodiment, but variations within the spirit and scope of the invention will occur to those skilled in the art. For example, it will be recognized that the shielding unit 210 could be in the form of a lead slug (having the shape of the member 140--see the dashed outline of FIG. 2) in those situations where the full front shielding is considered unnecessary.