X-ray or gamma ray systems or devices – Source support – Including object support or positioning
Reexamination Certificate
1997-11-10
2001-04-17
Porta, David P. (Department: 2876)
X-ray or gamma ray systems or devices
Source support
Including object support or positioning
C378S208000, C378S209000
Reexamination Certificate
active
06217214
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
The application relates to x-ray systems and methods and more particularly to x-ray based bone densitometry systems and methods and techniques useful at least in such systems and methods.
X-rays or gamma-rays can be used to measure the density and distribution of bone in the human body in order to help health professionals assess and evaluate projected bone mineral density, which in turn can be used to monitor age-related bone loss that can be associated with diseases such as osteoporosis. Additionally or alternatively, similar procedures can be used to measure non-bone related body content such as body fat and muscle. In bone densitometry, a patient typically is placed on a table such that the patient's spine extends along the length of the table, along a direction that can be called the Y-axis in Cartesian coordinates. For a supine patient, the left and right sides are in a direction typically called the X-axis. A source at one side of the patient transmits radiation through the patient to a radiation detector at the other side. The source and the detector typically are mechanically linked by a structure such as a C-arm to ensure their alignment along a source-detector axis which is transverse (typically perpendicular) to the Y-axis. Both x-ray tubes and isotopes have been used as a source of the radiation. In each case, the radiation from the source is collimated to a specific beam shape prior to reaching the patient to thereby restrict the field of x-ray or gamma radiation to the predetermined region of the patient opposite which are located the detectors. In the case of using x-rays, various beam shapes have been used in practice including fan beam, pencil beam and cone or pyramid beam shapes. When a fan beam is used, typically the beam conforms to a beam plane which is transverse (e.g., normal) to the Y-axis. Stated differently, the beam is wide in the plane and thin along the Y-axis. The shape of the beam and the shape of the detector system correspond. The detector in a fan beam system typically is an elongated array of detector elements arranged along a line or an arc. By means of mechanically moving the C-arm and/or moving the table, a region of interest in a patient on the table can be scanned with the radiation. Typical regions of analysis in bone densitometry include the spine, hip, forearm, and wrist, scanned individually. They can be covered individually within a reasonable time by a fan beam that has a relatively narrow angle in a single pass or, alternatively, by a pencil beam scanning a raster pattern. Another analysis region is termed “oblique hip” in which the hip is viewed at an angle relative to the horizontal and vertical directions. Another analysis region is referred to as “whole body” in which the entire patient body is scanned and analyzed for bone density and possibly also for “body composition” or the percentages of fat and muscle in the body.
X-ray bone densitometry systems have been made by the owner of this application under the tradenames QDR-2000+, QDR-2000, QDR-1500, QDR-1000plus, and QDR-1000. The following commonly owned U.S. patents pertain to such systems and are hereby incorporated by reference herein: U.S. Pat. Nos. 4,811,373, 4,947,414, 4,953,189, 5,040,199, 5,044,002; 5,054,048, 5,067,144, 5,070,519, 5,132,995 and 5,148,455; and 4,986,273 and 5,165,410 (each assigned on its face to Medical & Scientific Enterprises, Inc. but now commonly owned). Other bone densitometry systems are believed to have been made by the Lunar Corporation of Madison, Wis. (see, e.g., the system which is believed to be offered under the tradename Expert and U.S. Pat. Nos. 5,228,068, 5,287,546 and 5,305,368, none of which is admitted to be prior art against this application). It is believed that other manufacturers also have offered bone densitometry products.
The inventions disclosed in this application are directed toward bone densitometry features which are believed to overcome various shortcomings of such prior art systems. In a particular exemplary and non-limiting embodiment, the inventions are included in an x-ray bone densitometry system comprising a patient table having a length extending along a Y-axis and a width extending along an X-axis, a C-arm supporting an x-ray source at one side and an x-ray detector at an opposite side of said table, the source and detector being aligned along a source detector axis which is transverse to the Y-axis. When selectively energized, the source emits a fan beam of x-rays which conforms to a beam plane which is transverse to the Y-axis and contains the source-detector axis. At least one of said C-arm and table is selectively movable relative to the other along the X-axis, along the Y-axis, and along a Z-axis which is transverse to both the X-axis and the Y-axis, to selectively scan selected regions of a patient on the table with said fan beam of x-rays. In addition, the C-arm is selectively rotatable around a rotational axis extending along the Y-axis to selectively change the angle of the fan beam with respect to a patient on the table.
A beam modulator is mounted between the x-ray source and the table for rotation about a beam modulator axis which is transverse to the source-detector axis. The beam modulator is selectively rotatable about the beam modulator axis to cause the fan beam of x-rays to pass through a succession of beam modulating materials before reaching a patient on the table. These beam modulating materials having respective different effects on the x-rays impinging thereon, to modulate the beam for desired patient procedures and to serve other purposes such as to provide reference and calibration information.
An attenuator selector also is mounted between the x-ray source and the table and has a plurality of attenuating materials selectively movable to cause the fan beam to pass therethrough. Each of these attenuating materials attenuates the fan beam passing therethrough in a selected manner different from that of other attenuating materials to cause a desired change in beam parameters such as intensity, uniformity and energy spectrum.
A variable aperture collimator also is mounted between the x-ray source and the table to define the cross-section of the fan beam. The collimator can define the shape and size of the fan beam by passing x-rays through a selected one of several different slits in an x-ray opaque plate or, alternatively, can use a pair of plates selectively movable along the Y-axis to define one of the cross-sectional dimensions of the fan beam and a pair of plates movable along a direction transverse to both the Y-axis and the source-detector axis to define another cross-sectional dimension of the fan beam. A number of detector elements can be used to form said detector and to provide respective detector outputs related to the x-rays received at respective angular positions within the fan beam.
A detector response flattener can be used which is responsive to the detector outputs to process the outputs to account for at least one of: (i) non-uniformities in the fan beam; and (ii) non-uniformities in the response of detector elements. A dark current system can be used for interleaving the detector outputs with dark current responses of the detector elements on a substantially continuous basis, so as to use a dark current corrector which is responsive to the detector outputs and the dark current responses to account for dark current characteristics of the detector elements. An optical crosshair device can be mounted on the C-arm to project a visible crosshair co-axial with the source-detector axis and having a plane along the Y-axis and a plane normal to the Y-axis.
The scan motion controller can move at least one of the C-arm and the table relative to the other to scan at least a first region and then a second region of a patient on the table with the fan beam along the Y-axis, wherein the first region and said second region are next to each other along the X-axis, each region has an edge overlapping an adjacent edge of the other region
Cabral Richard E.
Gershman Russell J.
Cooper & Dunham LLP
Hologic Inc.
Porta David P.
LandOfFree
X-ray bone densitometry apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with X-ray bone densitometry apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and X-ray bone densitometry apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2475319