Patent Number: 052705498
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS There is shown in FIG. 1 an annular cylindrical multihole collimator 10 for a radioisotope camera. Collimator 10 is made up of a plurality of closed annular radio-opaque plates 12 and 12a each having a plurality of corrugations extending from the inner 16 to the outer 18 radius of the plate and defining one or more (actually three in FIG. 1) segment sections 20, 22 and 24, which combine to form three segments 26, 28 and 30 separated by junctions 32, 34 and 36. The junctions are uncorrugated areas between segment sections. If the collimator is to have but one segment then each plate will have but one corrugated segment section and the remainder of the plate will be all junction. The stacking of plates 12 and 12a along longitudinal axis 40, with their peaks 42 and valleys 44 aligned from plate to plate, create a multiplicity of holes 46. Each plate 12 or 12a, FIG. 2, may have the corrugations 14 converging as shown at 14a, diverging as shown at 14b, or parallel as shown at 14c. Segment sections 20', 22' and 24' may be crescent-shaped as shown in FIG. 2, or may have uniform inner and outer radii as shown in FIG. 1. Aligning means or indicia may be provided for assembly of plates 12 and 12a. For example, junctions 32', 34' and 36' may include alignment holes 50, 52, 54, respectively, for receiving alignment pins, or may include notches 56, 58, 60, or some other indicia to meet with a jig or guiding surface. If there is symmetry about a diametral axis through the center of one segment section, then plate 12 can be reversed and used in place of 12a. The assembly technique is shown in more detail in FIG. 3, where plates 12a, b, . . . , are stacked on a base ring 70 which contains alignment pins 72, 74 which are received in alignment holes 76, 78 in two of the four junctions 80, 82, 84, 86, which define the four segment sections 88, 90, 92, 94 that constitute the four segments 96, 98, 100 and 102. Between the junctions 84 of each plate 12" are fillers 104, 106, 108 and 110, which are radiologically opaque as are the junctions. Fillers 104 and 106 include holes 112 and 114 respectively, which receive guide pins 72 and 78 receivable in junctions 80 and 82. Cap ring 120 is fastened to alignment pins 72 and 74 by means of screws and washers 122 and 124, thereby unifying the entire assembly. Optionally, as shown in FIG. 4, assembly can be guided by means of pins which are parallel and provisionally reside in the corrugation holes 46 themselves, FIG. 4. Such pins 130, 134, 136 are shown radially disposed in each layer of holes 46. Preferably at least one additional set of guide pins 130a, 134a, 136a, is provided in order to provide two-dimensional alignment through the quadrature relationship of the pins. Plates 12 and 12a are bonded together by a suitable adhesive 140, FIG. 5, where their peaks and valleys contact. Pins 130, 134, 136, 130a, 134a, 136a are removed after bonding is complete. The corrugations may be triangular as shown in FIG. 5 to form square collimator holes 46, or the corrugations may be three-sided to form hexagonal holes as shown in FIG. 6. Alternatively, triangular corrugations may be used, as shown in FIG. 7, in staggered fashion with joiner plates 150 between them which are bonded to their peaks and valleys. Each plate 12 may be formed from a blank using a press and die set 160, FIG. 8, which cuts an annular blank 162 with two or more guide holes 164 and 166. Blank 162 is then placed in a corrugation die set 170 aligned by pins 190, 192 inserted in holes 160, 164, FIG. 9, to produce a finished corrugated piece 172. The method thus involves the first step 180, FIG. 10, of cutting the blank, followed by the corrugation step 182, after which the finished plates are assembled 184 as shown in FIG. 3 and bonded together, step 186, before they are finally capped 188, again as shown in FIG. 3. In accordance with the structure of FIG. 7, every other plate would be left uncorrugated: that is, step 182, depicted in FIG. 9, would be omitted and the flat blank plate 162 resulting from the operation in FIG. 8 would be used between the corrugated plates. Although specific features of the invention are shown in some drawings and not others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. Other embodiments will occur to those skilled in the art and are within the following claims: