Patent Number: 
Section: description

The invention provides a radiopharmaceutical pig (xe2x80x9cpigxe2x80x9d) and transportation apparatus, which is lighter and more efficient that conventional pigs and transportation apparatus. Turning to FIG. 1, the pig 10 of the present invention has an elongated tubular sidewall 12 that extends between two closed ends 14, 16. The two closed ends 14, 16 are thicker and contain relatively more radiation shielding material than is contained in the elongated tubular sidewall 12. The two closed ends 14, 16 and side wall 12 form an interior chamber 18 to house a radioactive substance which may be contained within a syringe 20. The pig 10 also has a plastic liner 22 fitted inside the chamber 18 for protecting the syringe inside the pig 10. The radioactive resistant material used to make the pig 10 may be lead, whose thickness at the two closed ends 14, 16 sufficiently shields against penetration of radiation through the closed ends 14, 16 and whose thickness at the elongated tubular sidewall 12 itself may not be sufficient to provide adequate shielding against penetration of radiation from the radioactive substances inside the pig 10. To compensate for this radiation shielding deficiency in the sidewall 12 of the pig 10, the pig 10 is fitted within a cavity 24 defined by a radiation shield 26, whose thickness in addition to the thickness of the sidewall 12 of the pig 10 is sufficient to resist penetration of radiation, preferably by an amount at least as great as the amount of radiation penetration resistance provided by the closed ends 14, 16. Although the radiation shield 26 is required for resisting radiation penetration with respect to the elongated tubular sidewall 12, the radiation shield 26 can be configured with open ends 28, 30 because the lead at the two closed ends 14, 16 of the pig 10 is sufficient to provide the necessary shielding above and below the radioactive source inside the syringe 32. This aspect allows the closed ends 14, 16 of the pig 10 to extend beyond each of the open ends 28,30 of the radiation shield 26, which provides for a combination pig 10 and radiation shield 26 that is relatively lightweight. The pig 10 is preferably configured as an assembly of two sections wherein the two sections are selectively mated with each other for closing the pig through a threading configuration or any other suitable method of mating the two sections (e.g., clasp, tong and groove, etc.). FIG. 2 shows the conventional 5 cc syringe 32 filled to capacity and closed with a luer lock 34. A luer lock 34 is often used by radiopharmaceutical manufacturers producing FDG F18 as a safety measure to prevent leakage. This is particularly important when air shipping the FDG F18 because the closed syringe must be able to withstand varied air pressures. The syringe 32 resides in the plastic liner 22 of the pig 10 (FIG. 3). As shown in FIG. 3, the pig 10 has two sections 36, 38 that mate with each other via a thread configuration 40. The thread configuration 40 is at the outside of inner end 42 of the section 38 at the inside of widened lip 44 of the section 36. Turning to FIG. 4, the radiation shield 26 is supported in a shipping container 46 such as a conventional metallic ammunition can or plastic or cardboard container. A sheet metal bracket 48 or some other sufficiently rigid bracket material 48 may be affixed to an inside surface in the case of the container 46 can and held in place with high density foam 50 (FIG. 5), such as high density polyurethane or polyethylene foam. Additional foam 50 between the base 56 of the container 46 (FIG. 1) and a lid 54 clamp the pig 10 in place upon fastening the lid 54 of the container 46. As shown in FIG. 1, radiation shield 26 is configured to define a cavity 24 into which the pig 10 is arranged. In the preferred embodiment, the radiation shield 26 has a contour that converges toward each of the open ends 28, providing a central area 56 between the two ends that is thicker than the area of the radiation shield 26 proximate to each of the ends. This configuration provides sufficient shielding while minimizing weight. Those skilled in the art will recognize that while the radiation shield 26 illustrated is contoured at both ends, only one end could be contoured, only part of one end could be contoured, the contour could be smaller, it could be arcuate rather than flat, etc. So long as the shape makes the weight less than a full cylindrical shape but maintains sufficient radiation shielding it will still fall within the scope of the invention. This highly efficient use of the radiation shield 26 allows for the adequate shielding of a FDG F18 dose as high as 700 mCi in containers that weigh less than 50 lbs. and still have a removable pig 10. A different, lighter weight, radiation shield 26 can be used for smaller doses by modifying the radiation shield 26, shown in FIG. 1, to have less lead to create an even lighter shipping container. This saves shipping charges and may also reduce the risk of injury to the people handling the containers as compared to conventional arrangements. According to DOT regulations, the radioactivity reading on the surface of the shipping container must be less than 50 mRems/hour and must also be less than about 1 mRems/hour at a reading that is taken at a distance of about 1 meter from the shipping container. The amount of lead required for adequate shielding is based on conventional formulae and tables that take into account the pharmaceutical properties, shielding material and distance between the radioactive substance and the outside of the shipping container. The required amount of shielding material drops off rapidly as the distance to the outside of the container increases. FIG. 6 shows the minimum profile for the amount of lead required in the radiation shield 26. The distance between the center of the syringe 32 to the outside of the shipping container 46 along the angles shown is in inches or centimeters. The thickness of lead required for proper shielding, at specific Rems per hour (R), is shown in inches at various angles. The numbers that appear in FIG. 6 near the center thereof show various required thicknesses of the lead forming the pig 10 of the present invention, in inches, for the angles shown. The distances from the radioactive substance to the outside of the shipping container 46 at the angles 58 shown and the thickness of lead in the pig 10 in inches are used to determine the thickness requirements of the radiation shield 26 at the particular angles. The thicknesses are plotted along the angle lines. These points are connected to show the minimum profile 60 of the lead radiation shield. The profile is then modified into a shape 62 that can be manufactured and supported by the shipping container 46. The minimum amount of lead required in the closed end portions of the pig is dependent upon the activity of the dose being shipped and the distance from the center of the radiopharmaceutical substance to the outside of the shipping container 46. For a dosage of 700 mCi, the end portions of the pig 10 near the lid 52 in the container 46 requires about 1{fraction (9/16)}xe2x80x3 lead and the other end portion requires about 1xe2x85x9exe2x80x3 lead. If 150 mCi are to be shipped, then about 1.20xe2x80x3 lead and 1.39xe2x80x3 lead would be required, respectively. FIG. 7 shows another embodiment of the invention for shipping multiple doses of radioactive substances in a single shipping container 46. FIG. 7 shows two individual pigs 10 each placed inside a respective radiation shield 26 configured to accommodate the two pigs 10. The double radiation shield 26 defines two cavities into which are arranged the two pigs 10 wherein the double radiation shield 26 and pigs 10 limit an amount of radioactivity emanating from the radioactive substances and penetrating the pigs 10 and shield 26 to less than about 50 mRems/hour at the surface of the container 46. This embodiment is particularly convenient for nuclear medical facilities that perform multiple PET imaging studies in a single day. The initial strength of each dose depends on the distance between the facility and on the duration of the multiple image studies. The double radiation shield 26 is supported by a sheet metal bracket 64 or some other suitable material, which may be placed inside a conventional container 46, configured to support the two pigs 10. High density foam 66, as described in connection with the first embodiment of the present invention, is used to keep the pigs 10 in place inside the container 46. Both pigs 10 and the double radiation shield 26 can fit into a standard ammunition can and still weigh less than about 50 lbs. FIG. 8 shows the syringes 32 and plastic liners used in a second embodiment of the present invention. Each syringe 32 is placed into its own pig 10. Each dose of radiation substance in each of the syringes 32 contains up to 150 mCi. The pigs 10 which now contain the two syringes 32 with their corresponding single doses of radiation substances are then placed into a double radiation shield 26 configured to accommodate the two pigs 10. High density foam 66 keeps the pigs 10 in place against moving inside the container 46. Although the above describes particular embodiments of the invention, many other variations and modifications and other uses may become apparent to those skilled in the art. It is preferred, that the present invention not be limited by this specific disclosure herein, but only by the appended claims.