X-ray or gamma ray systems or devices – Specific application – Computerized tomography
Reexamination Certificate
2000-06-05
2004-01-27
Bruce, David V. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Computerized tomography
C378S004000, C378S005000, C378S901000, C378S037000, C378S098110
Reexamination Certificate
active
06683934
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a digital x-ray imaging method and system for producing soft tissue images and bone/calcification images for radiography and mammography and, more particularly, to such a digital x-ray system employing dual (i.e., two different) x-ray energies, obtained by rapidly switching an x-ray energy source between low and high energy levels, and using a single large area pixelated digital x-ray detector to capture the resulting and respective, dual energy x-ray images. The dual energy images are processed, with a pre-calibrated database and adjustable parameters, to produce respective, and separate, soft tissue images and bone/calcification images, affording enhanced visibility of any nodules or clusters of calcification, facilitating earlier detection of lung and/or breast cancers.
In “normal” projection x-ray radiographic and mammographic images, nodules or clusters of calcifications can be obscured by structured noise/background, i.e., signal noise in the detected x-ray image caused by irradiation of bone structure (e.g., ribs or spine) or by contrast effects from, e.g., glandular and fatty tissues. In an effort to reduce such noise/background, dual energy x-ray imaging has been explored extensively, with both film/cassette systems and also digital systems.
Most of the early work in this field was based on film/cassette systems and, of necessity, employed a single x-ray energy spectrum and dual detectors. Particularly, with film/cassette systems, rapidly switching between high and low levels of x-ray energy (kVP) and using a single film/cassette for each image is not technologically feasible. Further, the limited dynamic range and lower detective quantum efficiency (DQE) of film/cassette systems preclude any such dual energy applications. The images obtained, moreover, were not acceptable.
Digital systems employing dual energy x-ray imaging offered at least the potential of improved images; however, there is a need in such systems of an increased separation of high and low X-ray energy levels yielding a practical, effective and efficient system performing dual energy X-ray imaging.
BRIEF SUMMARY OF THE INVENTION
The present invention utilizes a dual energy x-ray digital imaging system that includes an x-ray generator capable of switching from high energy to low energy rapidly (e.g., on the order of ms), a single, pixelated digital x-ray detector, a computer, a display unit and related software to acquire and process the high and low energy x-ray images for display.
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HibbsOpsahl-Ong Beale
Hopple Michael Robert
Zhao Jianguo
Bruce David V.
General Electric Company
Ingraham Donald S.
Patnode Patrick K.
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