US4097748A
Expired / Lapsed
US
⏱️ 0.0 years remaining
X-ray apparatus especially for mammography
Assignee: Thales SA
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Filing: 1977-04-05
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Granted: 1978-06-27
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Expires: 1997-04-05
Abstract
Abstract An X-ray machine, especially for mammography, includes an X-ray source and a suitable table or support for the object to be examined. The table is transparent to X-rays and holds sheets of X-ray film or the like to record the transmitted radiation. In addition to a fixed diaphragm which defines a substantially pyramidal primary beam, there are provided three sets of beam-defining slits, one behind the fixed diaphragm, one ahead of the object of examination and one just ahead of the recording medium. These three slits are disposed in geometrical similarity, i.e., their free width increases in proportion to their distance from the source. Furthermore, each of these slits is movable in a plane normal to the main axis of the primary beam. The three slits together define a narrow angular portion of the primary beam and their motion is so coordinated that the narrow beam is scanned across the object from one extreme position to the other. The successive slits reduce or eliminate the effects of blurring due to the finiteness of the sources and also pervent scattered radiation from the air or from the object of examination to reach the film.
Inventors
- 👤 Jacques Monvoisin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:46
CPC Classifications
A; A61; A61B; A61B6/00; A61B6/50; A61B6/502; A61B6/02; A61B6/06; G; G21; G21K; G21K1/00; G21K1/02; H; H05; H05G; H05G1/00; H05G1/02
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
202 words
In an X-ray machine, especially for mammography which includes a source of X-radiation, means for holding said source of X-radiation, for holding an object to be irradiated and for holding means for forming an image from said X-radiation, said source having a fixed diaphragm which defines a beam of X-radiation which has an angular deviation such that its shape resembles a pyramid of rectangular cross section, said X-ray machine further including beam-defining means for passing only a limited portion of said pyramidal beam, said beam-defining means being capable of motion in a plane perpendicular to the axis of said pyramidal beam, the improvement comprising: said beam-defining means includes in combination: a first slit disposed near said source for defining a narrow beam the long extent of which is substantially perpendicular to the motion of said beam-defining means; a second slit disposed near and ahead of said object; a third slit, disposed near and behind said object and ahead of said image forming means; and means for displacing said first, second and third slit in unison along mutually parallel planes and in a manner to maintain geometrical similarity, i.e., to maintain a line of sight through said slits to said source of X-radiation.
Claim 2
Dependent Claim
202 words
In an X-ray machine, especially for mammography which includes a source of X-radiation, means for holding said source of X-radiation, for holding an object to be irradiated and for holding means for forming an image from said X-radiation, said source having a fixed diaphragm which defines a beam of X-radiation which has an angular deviation such that its shape resembles a pyramid of rectangular cross section, said X-ray machine further including beam-defining means for passing only a limited portion of said pyramidal beam, said beam-defining means being capable of motion in a plane perpendicular to the axis of said pyramidal beam, the improvement comprising: said beam-defining means includes in combination: a first slit disposed near said source for defining a narrow beam the long extent of which is substantially perpendicular to the motion of said beam-defining means; a second slit disposed near and ahead of said object; a third slit, disposed near and behind said object and ahead of said image forming means; and means for displacing said first, second and third slit in unison along mutually parallel planes and in a manner to maintain geometrical similarity, i.e., to maintain a line of sight through said slits to said source of X-radiation.
Claim 3
Dependent Claim
44 words
A machine as defined by claim 1, wherein each of said first, second and third slits is defined by a pair of cooperating metal bars with adjacent substantially parallel edges, said edges being beveled to prevent reflected X-rays from entering the useful beam field.
Claim 4
Dependent Claim
107 words
An apparatus as defined by claim 1, the improvement further comprising an electric motor for moving said first and second slits and a mechanical transmission for coupling the motions of said first and second slits in a manner which maintains geometric similarity, i.e., a line of sight through said first and second slits to said source and further comprising a second motor for driving said third slit as well as a servo control circuit for moving said third slit in a manner dependent on the motion of said first and second slits and in a manner aligned angularly with the position of said first and second slits.
Claim 5
Dependent Claim
72 words
An apparatus as defined by claim 1, wherein each of said first, second and third slits is defined by substantially parallel metal bars, and wherein the width of the bars forming said first slit nearest said fixed diaphragm is such as to obstruct said diaphragm totally in the extreme lateral positions of said first slit and to permit a passage of only a narrow beam in positions in between said extreme positions.
Claim 6
Dependent Claim
39 words
A machine as defined by claim 4, wherein the width of the bars defining said second slit is such as to prevent a substantial portion of the geometric blurring due to the finite dimensions of the source of radiation.
Claim 7
Dependent Claim
69 words
An apparatus as defined by claim 1, further comprising a pair of radiation reflectors defined by two metal plates suspended to pivot from said bars defining said first slit and coupled to said bars forming said second slit; whereby the lower portion of said reflectors shares the motion of said second slit while permitting the passage of said narrow beam of X-radiation therebetween in all positions of said slits.
References Cited (Backward Citations)
US3866047A
Cited
US3790799A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-06-26 | 1981-12-26 | 1982-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-26 | 1985-12-26 | 1986-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-26 | 1989-12-26 | 1990-06-27 | $7700.00 | Window Closed / Lapsed |