X-ray or gamma ray systems or devices – Nonphotographic detector support
Reexamination Certificate
1999-11-25
2001-08-28
Kim, Robert H. (Department: 2882)
X-ray or gamma ray systems or devices
Nonphotographic detector support
C378S167000, C378S177000, C378S192000
Reexamination Certificate
active
06282264
ABSTRACT:
FIELD
This patent specification is in the field of radiography and pertains more specifically to the field of x-ray equipment using a digital flat panel detector.
BACKGROUND
Medical diagnostic x-ray equipment has long used x-ray film contained inside a lightproof cassette, with the cassette at one side of the patient and an x-ray source at the opposite side. During exposure, x-rays penetrate the desired body location and the x-ray film records the spatially varying x-ray exposure at the film. Over the years, medical experience has developed and optimized a variety of standard protocols for imaging various parts of the body, which require placing the film cassette in different positions relative to the patient. Chest x-rays, for example, are often performed with the patient standing, chest or back pressed against a vertical film cassette. Imaging of the bones in the hand might be done with the cassette placed horizontally on a surface, and the hand placed on top of the cassette. In another procedure the patient might cradle the cassette under an arm. A collection of such standard protocols is described in Merrill's Atlas of Radiographic Positions and Radiologic Procedures, by Philip W. Ballinger, et.al., 9th edition, published by Mosby-Year Book, Incorporated, hereby incorporated by reference.
Advances in digital x-ray sensor technology have resulted in the development of arrays of sensors that generate electrical signals related to local x-ray exposure, eliminating film as the recording medium. An example is discussed in U.S. Pat. No. 5,319,206, incorporated herein by reference, and a current version has been commercially available from the assignee of this patent specification. Such digital arrays are often called flat panel x-ray detectors, or simply flat panel detectors, and offer certain advantages relative to x-ray film. There is no need for film processing, as the image is created and comes from the cassette in electronic digital form, and can be transferred directly into a computer. The digital format of the x-ray data facilitates incorporating the image into a hospital's archiving system. The digital flat panel detectors or plates also offer improved dynamic range relative to x-ray film, and can thus overcome the exposure range limitations of x-ray film that can necessitate multiple images to be taken of the same anatomy. On the other hand, digital flat panel detectors currently have a higher capital cost than film cassettes, and are more fragile. They often incorporate lead shielding to protect radiation-sensitive electronics, and can be heavy. If they are connected to a computer with a cable, cable handling needs to be taken into consideration when moving the cassette and/or the patient. Alternatively, the cassette can be self-contained, as for example in U.S. Pat. No. 5,661,309, in which case it includes a power supply and storage for the image information, increasing its weight and possibly size. Such detectors commonly are used in a system comprising a suitable anti-scatter or Bucky plate.
The high initial cost of the digital detector can hinder outfitting of an x-ray room with multiple detectors pre-mounted in a variety of positions, such as a vertically-mounted unit for chest, and a horizontal unit under a bed. The fragility, weight, and initial cost of the units make them difficult to use in procedures where the patient cradles the detector. The unique characteristics of digital flat panel detectors can make conventional film cassette holders impractical for use with flat panel detectors.
A number of proposals have been made for x-ray systems using flat panel detectors. A C-arm arrangement has been offered under the name Traumex by Fisher Imaging Corporation of Denver, Colo., with the participation of a subsidiary of the assignee hereof. Another C-arm arrangement is believed to be offered under the name ddRMulti-System by Swissray, and literature from Swissray has stated that a ddRCombi-System is scheduled for launch in early 2000 and would offer the same functionality as the ddRMulti-System but would use existing third party suspension equipment for the x-ray tube (an illustration therein appears to illustrate a detector arrangement mounted for vertical movement on a structure separate from a ceiling-mounted x-ray tube support. A vertically moving and rotating image intensifier appears to be illustrated in FIG. 3 of U.S. Pat. No 4,741,014. U.S. Pat. No. 5,764,724 proposes yet another a patient table and can be moved to a number of position along the table edge.
A number of other proposals have been made for positioning x-ray film cassettes but the different physical characteristics and requirements of flat panel detectors systems do not allow for direct application of film cassette positioning proposals. For example, U.S. Pat. No. 4,365,344 proposes a system for placing a film cassette in a variety of positions and orientations relative to a floor mounted x-ray source support. U.S. Pat. No. 5,157,707 proposes moving a film cassette to different positions relative to a ceiling mounted x-ray tube support to allow taking AP (anterior-posterior) and lateral chest images of a patient sitting on a bed. The figures of Swedish patent document (Utlaggningsskrif [B]) 463237 (application 8900580-5) appear to show a similar proposal as well as a proposal to mount the x-ray cassette and the x-ray source on the same structure extending up from the floor. U.S. Pat. No. 4,468,803 proposes clamping an articulated support for a film cassette on a patient table, and U.S. Pat. No. 5,920,606 proposes a platform on which a patient can step and into which a film cassette can be inserted to image a weight-bearing foot.
With a view to the unique characteristics and requirements of digital flat panel detector systems, it is believed that a need exists to provide a safe, reliable, convenient and effective way to position such systems for a wide variety of imaging protocols, and this patent specification is directed to meeting such a need.
SUMMARY
An exemplary and non-limiting embodiment comprises a digital, flat panel, two-dimensional x-ray detector system that is not mechanically coupled to x-ray source motion and can safely and conveniently move to any one of a wide variety of positions for standard or other x-ray protocols and can securely maintain the selected position to take x-ray images, thus making it possible to use a standard x-ray source in an x-ray room, such as a ceiling-mounted source, with a single digital flat panel detector for x-ray protocols that might otherwise require plural detectors.
One preferred embodiment, described by way of an example and not a limitation on the scope of the invention set forth in the appended claims, comprises a detector that is free of a mechanical connection with an x-ray source and includes a digital flat panel x-ray detector arrangement and an anti-scatter grid. A floor-supported base supports an articulated structure that in turn supports and selectively moves the detector with at least five degrees of freedom to position it for any one of a variety of standard or other diagnostic x-ray protocols for standing, sitting, and recumbent patients. In a non-limiting example, the degrees of freedom include at least two translational and three rotational motions. For example, a first translational motion comprises moving a lower slide along the base, a first rotational motion comprises rotating about a vertical axis a lower arm having a near end mounted on the lower slide, a second rotational motion comprises rotating about another vertical axis a column mounted at a far end of the lower arm, a second translational motion comprises moving an upper slide up and down the column, and a third rotational motion comprises rotating about a horizontal axis an upper arm having a near end mounted on the upper slide and a far end coupled to the detector. In addition, the detector can be rotationally mounted on the far end of the upper arm to rotate about an axis transverse to its face, for a sixth degree of freedom. The detector can a
Cabral Richard E.
Miller James D.
Rossi Remo
Smith Andrew P.
Stein Jay A.
Cooper & Dunham LLP
Ho Allen C.
Hologic Inc.
Kim Robert H.
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