X-ray beam filter device

Claim 2

A filter device for being interposed in an x-ray beam projected from an x-ray source, the device comprising: a base member, a first generally planar filter element and a second generally planar filter element adjacent the first element and. substantially coplanar therewith, said first and second elements being joined to form a unitary member mounted for travelling between limit positions relative to the base member in one plane that is transverse to the path of the central ray of the x-ray beam, and reversible motor means and means operatively coupling said motor means to said unitary filter member comprised of said first and second filter elements for said motor means to drive said member selectively and linearly in opposite directions to dispose said filters alternately in the x-ray beam path.

Claim 3

The filter device according to claim 1 wherein said first filter element is copper and said second filter element is gadolinium.

Claim 4

The device according to claim 1 in combination with an x-ray beam collimator having blades movable across the x-ray beam path to define the size of the x-ray beam field, said collimator blades being located between said x-ray source and said filter elements and such that said elements are at a substantially minimum distance from said x-ray source.

Claim 5

The filter device according to any one of claims 1, 2 or 3 wherein said unitary member is comprised of a strip of one filter material a part of which constitutes said first filter element and said strip has an aperture adjacent said part in alignment with which said second filter element is fastened.

Claim 6

The filter device according to claim 4 wherein said strip comprises copper.

Claim 7

The filter device according to claim 4 wherein said strip comprises iron.

Claim 8

The filter device according to claim 4 wherein said second filter element comprises gadolinium.

Claim 9

The filter device according to claim 1 wherein said first filter element is selected from the class consisting of copper and iron and the second filter element is selected from the class consisting of elements in the atomic number range of 58 to 71.

Claim 10

A filter device for being interposed in an x-ray beam projected from an x-ray source, the device comprising: a base member, a first generally planar filter element and a second generally planar filter element adjacent the first element and substantially coplanar therewith, said first and second elements being joined to form a unitary member mounted for travelling between limit positions relative to'the base member in one plane that is transverse to the path of the central ray of the x-ray beam, a third planar filter element mounted for travelling relative to said base member in a second plane parallel to said one plane, means on said unitary member and third filter element cooperating to cause said member to pull said third filter element into the beam path when said member is driven toward and to one limit of its travel and to push said third element out of the beam when said member is driven toward and to the other limit of its travel, and reversible motor means and means operatively coupling said motor means to said member comprised of said first and second filter elements for said motor means to drive said member selectively in opposite directions to obtain a plurality of filtering modes, in one of said modes, driving the unitary member to said one limit position causing said third element to be pulled into the beam, in another of said modes, driving the unitary member to the other of said limit positions to push said third element out of the beam path and thereby permit said member to be oscillated under the influence of said motor to position said first and second filter elements alternately in the beam path, and in another mode wherein said member is first moved to said one limit to pull said third filter element into the beam path and then said member is oscillated to position the first filter element in the beam path with the third element and alternately to let only the third filter element remain in the beam path.

Claim 11

A filter device for being interposed in an x-ray beam projected from an x-ray source, the device comprising: a base member, a first generally planar filter element and a second generally planar filter element adjacent the first element and substantially coplanar therewith, said first and second elements being joined to form a unitary member mounted for travelling between limit positions relative to'the base member in one plane that is transverse to the path of the central ray of the x-ray beam, a third planar filter element mounted for travelling relative to said base member in a second plane parallel to said one plane, means on said unitary member and third filter element cooperating to cause said member to pull said third filter element into the beam path when said member is driven toward and to one limit of its travel and to push said third element out of the beam when said member is driven toward and to the other limit of its travel, and reversible motor means and means operatively coupling said motor means to said member comprised of said first and second filter elements for said motor means to drive said member selectively in opposite directions to obtain a plurality of filtering modes, in one of said modes, driving the unitary member to said one limit position causing said third element to be pulled into the beam, in another of said modes, driving the unitary member to the other of said limit positions to push said third element out of the beam path and thereby permit said member to be oscillated under the influence of said motor to position said first and second filter elements alternately in the beam path, and in another mode wherein said member is first moved to said one limit to pull said third filter element into the beam path and then said member is oscillated to position the first filter element in the beam path with the third element and alternately to let only the third filter element remain in the beam path.

Claim 12

The filter device according to claim 9 wherein said first filter element is copper, said second filter element is gadolinium and the third filter element is aluminum.

Claim 13

The device according to claim 9 in combination with an x-ray beam collimator having blades movable across the x-ray beam path to define the size of the x-ray beam field, said collimator blades being located between said x-ray source and said filter elements and such that said elements are at a substantially minimum distance from said x-ray source.

Claim 14

A filter device for use in an x-ray beam that is projected from an x-ray source, the device comprising: first and second substantially planar filter elements composed of first and second x-ray filtering materials, said elements being substantially coplanar and adjacent each other and joined to form a unitary member, guide means for guiding said unitary member to travel in a first plane that is transverse to the path of the central ray of the x-ray beam, a third substantially planar filter element and guide means for guiding said third element to travel in a second plane that is parallel to said first plane, reversible motor means and means operatively coupling said motor means to said unitary filter member for driving the member whereby by control of said motor said member can be caused to travel to one and the other of its opposite end positions and to a position intermediate of said end positions, first and second lug means spaced apart on said third filter element in the direction of its travel, third lug means on said unitary filter member projecting between and in the path of travel of the first and second lug means on said third element, whereby when said unitary member is driven to one of said end positions said first lug means will be engaged by the third lug means to position the third filter element in the x-ray beam path, when said member is driven to the opposite end position by engagement of said third and second lug means said third element is forced out of the beam to permit said unitary member to be oscillated between said opposite end position and an intermediate position to dispose said first and second filter elements alternately in the beam, and when said member is driven to said one end position coaction of said lug means will cause said third element to be disposed in the beam and when driven to an intermediate position will cause said first filter element to be positioned in the beam along with said third filter element.

Claim 15

A filter device for use in an x-ray beam that is projected from an x-ray source, the device comprising: first and second substantially planar filter elements composed of first and second x-ray filtering materials, said elements being substantially coplanar and adjacent each other and joined to form a unitary member, guide means for guiding said unitary member to travel in a first plane that is transverse to the path of the central ray of the x-ray beam, a third substantially planar filter element and guide means for guiding said third element to travel in a second plane that is parallel to said first plane, reversible motor means and means operatively coupling said motor means to said unitary filter member for driving the member whereby by control of said motor said member can be caused to travel to one and the other of its opposite end positions and to a position intermediate of said end positions, first and second lug means spaced apart on said third filter element in the direction of its travel, third lug means on said unitary filter member projecting between and in the path of travel of the first and second lug means on said third element, whereby when said unitary member is driven to one of said end positions said first lug means will be engaged by the third lug means to position the third filter element in the x-ray beam path, when said member is driven to the opposite end position by engagement of said third and second lug means said third element is forced out of the beam to permit said unitary member to be oscillated between said opposite end position and an intermediate position to dispose said first and second filter elements alternately in the beam, and when said member is driven to said one end position coaction of said lug means will cause said third element to be disposed in the beam and when driven to an intermediate position will cause said first filter element to be positioned in the beam along with said third filter element.

Claim 16

The filter device according to claim 12 wherein said unitary member is comprised of a strip of one filter material a part of which constitutes said first filter element and said strip has an aperture adjacent said part in alignment with which said second filter element is fastened.

Claim 17

The filter device according to claim 13 wherein said strip comprises copper.

Claim 18

The filter device according to claim 13 wherein said strip comprises iron.

Claim 19

The filter device according to any of claims 12, 13, 14 or 15 wherein said third filter element comprises aluminum.

Claim 20

The filter device according to any of claims 12, 13, 14 or 15 wherein said second filter element comprises gadolinium.

Claim 21

The filter device according to claim 12 including engagement means spaced apart from each other along the path of travel of said third filter element, one of said engagement means engaging detachably with said third filter element when it is positioned in the x-ray beam path and the other of said engagement means- engaging detachably with said third filter element when it is positioned out of the beam path to thereby prevent said third element from shifting under the influence of gravity, the force applied to said third filter element by movement of said unitary filter member being sufficient to engage and detach said engagement means and third filter element.

Claim 22

The filter device according to claim 12 including latch elements spaced from each other along the path of travel of said third filter element and pivotable about an axis perpendicular to the plane in which said third element travels, said latch elements each having a slot extending substantially radially away from said axis, pin means projecting perpendicularly from said third filter element into the plane of said latch elements for entering one slot or the other when said third element approaches one or the other of its final positions to thereby rotate the latch element, and spring means acting on said latch elements and whose force must be overcome by driving said filter element to thereby rotate said latch elements and which spring means then applies said force for holding said latch element against rotation to thereby lock the third filter element against moving under the influence of gravity.