EP0040158A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
A scanning grid apparatus for suppressing scatter in radiographic imaging
Assignee: University of Alabama
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Filing: 1981-05-13
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Granted: —
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Expires: 2001-05-13
Abstract
Abstract A scanning grid apparatus exhibiting high primary and low secondary X-Ray transmission of X-Ray radiation emitted from an X-Ray source defining a focal spot, including at least one scanning grid provided with top and bottom pairs of opposed grid slat retainers disposed in parallel planes. Pivotably attached between the top pair of retainers is a plurality of radiopaque linear or wavy grid slats separated at predetermined distances in the plane of the top pair of retainers. The bottom pair of retainers includes spacers for maintaining the grid slats separated predetermined distances within allowable limits in the plane of the bottom pair of retainers. The separation distances provided by the bottom pair of retainers is chosen as the geometric projection of the separation distances in the plane of the top pair of retainers from the source focal spot to the plane of the bottom pair of retainers, such that each of the grid slats is focused on the focal spot of the X-Ray source. The pairs of grid slat retainers are mechanically coupled to the source focal spot by means of a slotted linkage arm capable of moving the pairs of grid slat retainers linearly in the direction transverse to the plural grid slats to blur out and render invisible slat shadows which would otherwise appear on an image receptor, while nevertheless maintaining the grid slats focused on the source focal spot to reduce primary radiation cut-off. A pair of scanning grids in which the grid slat retainers of the respective grids are arranged orthogonally may be staggered between a subject and an X-ray image receptor to further suppress secondary radiation.
Inventors
- 👤 Gary T. Barnes
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 20:24
CPC Classifications
G; G21; G21K; G21K1/00; G21K1/02; G21K1/025; A; A61; A61B; A61B6/00; A61B6/06; A61B6/42; A61B6/4291
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
286 words
A scanning grid apparatus capable of exhibiting high primary and low secndary x-ray transmission of x-ray radiation emitted from an x-ray source defining a focal spot when said emitted radiation passed through a subject, the scanning grid apparatus and then onto an x-ray sensitive image receptor, comprising; at least one scanning grid comprising, a first pair of opposed longitudinally extending grid slat retainers, a second pair of opposed longitudinally extending grid slat retainers, said pairs of grid slat retainers disposed in parallel planes with said first pair adapted to be located between said subject and said second-pair, and a plurality of radiopaque grid slats pivotably attached at pivot points at predetermined intervals between the retainers of one of the pairs of said grid slat retainers, the other pair of said retainers comprising spacing means for maintaining said grid slats separated predetermined distances within predetermined limits in the plane of said other pair of retainers, said predetermined intervals between slats pivotably attached to the one pair and the separation distances between slats along the other pair selected to focus each of said slats on said focal spot, and means for coupling at least said one of said pairs of retainers to said x-ray source for moving said at least one of said pair of retainers longitudinally sweeping in a direction tranverse to said plural grid slats to sweep said grid slates in relation to the position of said x-ray source; wherein said grid slats are maintained focused on said focal spot during the longitudinal movement of said at least one pair of ratainers by the spacing means of the other pair of retainers and the pivotal attachment of said grid slats to said one pair of retainers.
Claim 2
Dependent Claim
286 words
A scanning grid apparatus capable of exhibiting high primary and low secndary x-ray transmission of x-ray radiation emitted from an x-ray source defining a focal spot when said emitted radiation passed through a subject, the scanning grid apparatus and then onto an x-ray sensitive image receptor, comprising; at least one scanning grid comprising, a first pair of opposed longitudinally extending grid slat retainers, a second pair of opposed longitudinally extending grid slat retainers, said pairs of grid slat retainers disposed in parallel planes with said first pair adapted to be located between said subject and said second-pair, and a plurality of radiopaque grid slats pivotably attached at pivot points at predetermined intervals between the retainers of one of the pairs of said grid slat retainers, the other pair of said retainers comprising spacing means for maintaining said grid slats separated predetermined distances within predetermined limits in the plane of said other pair of retainers, said predetermined intervals between slats pivotably attached to the one pair and the separation distances between slats along the other pair selected to focus each of said slats on said focal spot, and means for coupling at least said one of said pairs of retainers to said x-ray source for moving said at least one of said pair of retainers longitudinally sweeping in a direction tranverse to said plural grid slats to sweep said grid slates in relation to the position of said x-ray source; wherein said grid slats are maintained focused on said focal spot during the longitudinal movement of said at least one pair of ratainers by the spacing means of the other pair of retainers and the pivotal attachment of said grid slats to said one pair of retainers.
Claim 3
Dependent Claim
31 words
A scanning grid apparatus according to Claim 1, further comprising: said grid slats pivotably attached to said first pair of retainers; and said second pair of retainers including said spacing means.
Claim 4
Dependent Claim
47 words
A scanning grid apparatus according to Claim 1, adapted to be used in conjunction with a stationary x-ray source, futher comprising: said coupling means comprisig means for longitudinally moving said second pair of retainers a distance proportional to the longitudinal movement of said first pair of retainers.
Claim 5
Dependent Claim
75 words
A scanning grid apparatus according to Claim 3, wherein said coupling means comprises: said first and second pairs of retainer provided with respective coupling pegs; and a lingkage arm pivoted along a line passing through the focal spot and parallel to said grid slats, said arm having slots coupling said pegs of said pairs of retainers such that pivotal rotation of said arm produces the longitudinal movement of the first and second pairs of retainers.
Claim 6
Dependent Claim
103 words
A scanning grid apparatus according to Claim 1, adapted to be used in conjunction with an x-ray source and an x-ray sensitive receptor undergoing a tomographic movement, wherein said coupling means comprises: means for maintaining said second pair of retainers stationary during said tomographic movement, said first pair of retainers having a coupling peg, and a linkage arm coupled to said source and pivoted along a line passing through the focal spot and parallel to said grid slats, said arm having a slot coupling said peg such that tomographic movement of said source produces the longitudinal movement of the first pair of retainers.
Claim 7
Dependent Claim
49 words
A scanning grid appparatus according to Claims 1, 2, 3, 4, or 5, further comprising: each of said grid slats having a wavy cross-section with the period of the waves diverging from the first pair of retainers to the second pair of retainers in convergence on said focal spot.
Claim 8
Dependent Claim
30 words
A scanning grid apparatus according to Claim 6, further comprising: said wavy grid slats intermeshed to obstruct x-ray scatter radiation having components parallel to the plane of said grid slats.
Claim 9
Dependent Claim
248 words
A scanning grid apparatus according to Claims 1, 2, 3, 4, or 5, further comprising: a second scanning grid in addition to said at least one scanning grid, said second scanning grid likewise adapted to be disposed between said subject and said image receptor and comprising: third and forth pairs of longitudinally extended opposed grid slat retainers disposed in respective parallel planes, said third and fourth pairs arranged orthogonal to said first and second pairs with said third pair adapted to be located between said subject and said fourth pair, and plural radiopaque grid slats pivotably attached at predetermined intervals between a selected one of said third and fourth pairs of retainers, the other of said third and fourth pairs comprising spacing means for maintaining said grid slats of said second scanning grid separated within predetermined limits in the plane of said other of said third and fourth pairs of retainers, the grid slats of said second scanning grid maintained focused on said focal spot by said spacing means; and means for coupling said third and fourth pairs of retainers for longitudinally moving at least said third pair of retainers in a direction transverse to the plural grid slats of said second grid to sweep the grid slats of the second grid in relation to the position of said x-ray source; wherein said grid slats of said second scanning grid are maintained focused on said focal spot during longitudinal movement of said third and fourth pairs of retainers.
Claim 10
Dependent Claim
42 words
A scanning grid apparatus according to Claim 1, wherein the predetermined separation distances maintained by said spacing means corresponds to the geometrical projection from the focal spot of the grid slat pivotal attachment intervals to the other pair of grid slat retainers.
Claim 11
Dependent Claim
73 words
A scanning grid apparatus according to Claim 9, wherein the predetermined limits within which said grid slats are maintained separated by said spacing means is defined by the following relationship: where X corresponds to said predetermined limits, x is the slat thickness, L is the distance from the source focal spot to the spacing means, and 1 is the distance from the source focal spot to the pivot points of said grid slats.
Claim 12
Dependent Claim
32 words
A scanning grid apparatus according to Claim 1, wherein at least one of said grid slats comprises: a mechanically rigid substrate; and at least one x-ray absorbing septum laminated to said substrate.
Claim 13
Dependent Claim
21 words
A scanning grid apparatus according to Claim 11, further comprising: said substrate formed of steel; and said septum formed of lead.
References Cited (Backward Citations)
US1484663A
Cited
DE370123C
Cited
DE387082C
Cited
US4126786A
Cited
US4096391A
Cited
EP0014339A1
Cited
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