Patent Number: 048517020
Section: description

STRUCTURE Referring to FIG. 1, radiopaque sleeve 14, containing microtube 12, containing radioactive solution 19, has a flange 24 for suspending it from a top shelf 16 of a rack 10, and a lower tapered portion 26 which extends through a lower shelf 18 of rack 10. Sleeve 10 is inserted within two concentrically aligned holes 20, 22 in rack 10. The bottom of sleeve 14 is slightly elevated from the lowest level 15 of the rack. Sleeve 14 is made of radiopaque plastic, such as Plexiglass.TM., (acrylic) or Lexan.TM. (polycarbonate) and is approximately 1/4 inch thick. This thickness is sufficient to block high energy .beta.-particles. The inner diameter of sleeve 14 is approximately equal to the outer diameter of microtube (about 1.0 cm) 12 so that when microtube 12 is inserted into sleeve 14, they are in close proximity. When microtube 12 is placed within sleeve 14, it extends only a portion of the way through sleeve 14. This prevents radiation from emanating from solution 19 in a horizontal direction. Both the outer surface and the inner surface of the sleeve are substantially optically transparent to allow visual inspection of solution 19. Lid 28 of microtube 12 is elevated from flange 24 by a circular ridge 30 (or alternatively dimples) to facilitate access to lid 28. The base 31 of sleeve 14 is substantially flat, which allows it to rest in a free standing position so that sampling of the contents of microtube 12 is readily performed. Placed on rack 10, the geometry of sleeve 14 (open at the top and bottom) permits liquid in any incubator bath to directly enter sleeve 14 through bottom opening 33 and surround that portion of the microtube enclosing solution 19 contained in microtube 12. OTHER EMBODIMENTS Other embodiments are within the following claims. For example, referring to FIG. 2, an incubation rack 32 is designed for suspending several microtubes 34, 36 (only two are shown) from a single radiopaque shelf 38. A plastic skirt 40 surrounds the perimeter of shelf 38 and encloses microtubes 34, 36 suspended from shelf 38 (for clarity the front of skirt 40 is not shown). To prevent lateral radiation, skirt 40 extends just above and below the suspended microtubes 34, 36. Skirt 40 is elevated by two handles 44, 46 to permit incubation rack 32 to be placed in any water bath and allow incubation water (not shown) to circulate around the lower portion of microtubes 34, 36. A plastic lid 42 is hinged to skirt 40 and serves to block radiation emanating upward. Skirt 40 and lid 42 are made of transparent plastic at least 1/4 inch thick for blocking .beta.-emmitting particles. Identifying marks for suspended microtubes can be made on top of lid 42. Referring to FIG. 3, a block of transparent, radiopaque material 48 is provided with a plurality of bores 50 which extend through block 48. Preferably block 48 is made of plastic such as Plexiglass.TM. and has a minimum thickness T of 1/4 inch between bores 50 along the perimeter of block 48. Radioactive emission from the solution contained in microtubes 34, 36 is therefore limited to the top and bottom openings of bore 50. Handles 52 elevate block 48 and permit incubation water to circulate around microtubes 34, 36 suspended from the top of block 48.