X-ray or gamma ray systems or devices – Specific application – Tomography
Reexamination Certificate
1998-11-25
2001-05-22
Church, Craig E. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Tomography
Reexamination Certificate
active
06236708
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the art of tomographic imaging. It finds more particular application in 3D and 2D tomographic imaging based on one or more layers in a human body being measured by an x-ray system. However, it will be appreciated that the invention has other applications such as imaging of an object with other types of penetrating radiation to determine the make up and constituent components of that object and it may be advantageously employed in other environments and applications.
Traditionally, x-rays are projected from an x-ray source and through an object for exposing an image onto x-ray film. The image is typically a compression of all of the structures in the imaged portion of the body exposed onto the x-ray film. The vast amount of superimposed information can make diagnosis difficult.
In one technique for emphasizing a selected plane of the object, the x-ray source and the x-ray film move contra-cyclically in parallel planes which are parallel to the plane of interest. More specifically, the x-ray source and the x-ray film are moved such that the ray which exposes each incremental element of the x-ray film pivots about a fixed point in the plane of interest or focal plane. In this manner, each incremental element of the x-ray film is consistently exposed by radiation passing through a constant point in the focal plane. However, because the ray is pivoting about the constant point, the same increment of x-ray film is also exposed by a variety of structures outside the focal plane. In this manner, information from structures outside of the focal plane become blurred on the same x-ray film on which image data attributable to structures on the focal plane remains sharp and crisp.
If the diagnostician wishes to view another selected plane, the position of the patient is shifted relative to the x-ray source and the x-ray film canister such that the focal plane passes through a different selected plane of the object. With sufficient time, a series of parallel planer film images can be generated through the object. However, because each image takes a significant amount of time to generate, there is a significant temporal offset or time evolution among the images.
The temporal offset can be greatly reduced with volumetric CT scanners. However, CT scanners are not only much larger and more complex then the traditional x-ray film imaging systems, they are also much more expensive. Moreover, CT scanners are a different piece of equipment often positioned in a different room or location within the facility and in some instances at a different facility completely. Typically, the CT scanners are operated by different technicians. Accordingly, there are time delays in transporting the patient from one piece of equipment to the other, sometimes involving the making of additional appointments. Thus, the film images and the CT images may have very large temporal offsets. Moreover, it is difficult to maintain the position and orientation of the patient constant during such transporting. Accordingly, the resultant CT images are often not of the same physiology as the film images.
The present invention contemplates a new and improved apparatus and method which overcomes the above-referenced problems and others.
SUMMARY OF THE INVENTION
In accordance with the present invention, a device for imaging an object generates a multi-dimensional image of the object. The device includes a movable light source for sending a radiation beam through the object. A detector detects the radiation beam after it has passed through the object and generates electronic data representative of the detected radiation intensity. A system non-linearly displaces the radiation source relative to the object during the imaging. A processor receives, sorts, and processes the data to generate a series of stacked planar images of the object, each of which has minimized blurring in a corresponding plane and enhanced blurring outside of the corresponding plane.
In accordance with a more limited aspect of the present invention, the x-ray source moves in an arc to minimize magnification distortion by aligning the center of the cone beam with the region of interest.
In accordance with another more limited aspect of the present invention, the radiation source moves transversely to and along the arc to enhance off-plane blurring.
In accordance with another more limited aspect of the present invention, the radiation source is movably mounted below the object and a flat panel detector is located above the object in a stationary position.
In accordance with a more limited aspect of the present invention, the radiation source and the detector are located on opposite sides of an object support. The gantry moves the x-ray source up and down and left to right in relation to a flat panel detector.
A first advantage of the present invention is that it concurrently generates data for processing a plurality of layers.
Another advantage of the present invention resides in a reconstruction technique which quickly and easily reconstructs 2D and 3D tomographic images.
Another advantage is that electronic image representations are generated.
Yet another advantage is that the imaged planes can be changed after the data collection process is complete.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.
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Griesmer Jerome J.
Lin Zhongmin
Negrelli Donald E.
Plut Leonard F.
Church Craig E.
Fay Sharpe Fagan Minnich & McKee LLP
Picker International Inc.
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