Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1997-11-07
2001-05-08
Casler, Brian L. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
Reexamination Certificate
active
06228028
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for image reconstruction and particularly to a method and apparatus for three- and four-dimensional image reconstruction.
BACKGROUND OF THE INVENTION
Ultrasound imaging is becoming increasingly popular as a replacement for X-ray imaging techniques due to the health hazards associated with x-ray radiation. In ultrasound imaging, one or more emitting piezoelectric transducers are placed into contact with the patient's skin and energized to generate one or more ultrasound signals. The ultrasound signals are reflected by changes in tissue density, such as by the organ of interest, and the reflected signals received by one or more receiving piezoelectric transducers. The collected data, namely the time (measured from the time of signal emission) required by the signal to be received by the receiving piezoelectric transducer(s) and the intensity of the received signal, can be combined with the position (x,y,z) and orientation (alpha, beta, gamma) of the probe to generate a plurality of two-dimensional scanning or imaging planes. To form a three-dimensional image of the organ, an output volume containing a number of elements is generated. A gray-scale value is assigned to each element by sequentially and independently processing each of the scanning planes.
In designing an efficient three-dimensional ultrasound imaging system, there are a number of considerations. First, image data should not be ignored during generation of the output volume. The quality of the image can be negatively impacted by the failure to consider image data in the scanning planes. Second, the processing of the image data in all of the scanning planes should be performed quickly and with the least amount of memory space. Third, the user should have the option of utilizing a number of different algorithms to process the image data in the scanning planes. This flexibility permits the user to select the algorithm producing the highest quality image.
SUMMARY OF THE INVENTION
These and other design objectives are realized by the ultrasound imaging method of the present invention. The method can construct three- or four-dimensional image of an object, such as an organ (e.g., for medical diagnosis) or a machine part (e.g., for defect identification). The system includes at least the following steps:
(a) generating a plurality of image (or scanning) planes, each image plane containing image information describing an object; and
(b) determining the image information in each of the plurality of image planes that is within a defined portion of an output volume to define a first subset of image information corresponding to the defined portion. The defined portion of the output volume can be an image element of any number of dimensions, such as pixels (i.e., two-dimensional image elements), voxels (i.e., three-dimensional image elements) or toxels (i.e., four-dimensional image elements).
As noted, the generating step is commonly performed by manually passing an ultrasound probe over the object or by electronically pulsing differing piezoelectric transducers in a transducer array. The position of the ultrasound probe is typically determined by a position sensor attached to the ultrasound probe.
The spatial offset(x, y, z, ∝, &bgr;, &ggr;) offset between the the position sensor or the used probe and the ultrasound-beam generating piezoelectric transducer in the transducer array must be determined. This offset can be determined by utilizing different methods. By way of example, a measurement with a three-dimensional ultrasound phantom can be performed. The offset can be determined by measuring defined landmarks in phantom images acquired from different directions.
The output volume generally includes a plurality of defined portions. The determining step is therefore repeated for each of the plurality of defined portions to define a subset of image information corresponding to each of the plurality of defined portions.
The image information typically includes location coordinates (i.e., x,y,z) relative to a reference axis, an angular orientation of the probe (alpha, beta, gamma) and gray scale value. As used herein, “gray scale value” refers to the gray scale value with or without color information, tissue doppler imaging information, or any other parameter describing the appearance of the object. The output volume is typically defined by three orthogonal reference axes. In the determining step, the image information that is located within the defined portion or that is within a selected distance of the defined portion is identified to define the first subset of image information.
The first subset of image information can be analyzed to define a second set of image information that is derived from the first subset of image information. The second subset of image information is different from the first subset of image information. The analysis can be performed using any known interpolation algorithms, including the first found algorithm, the closest distance algorithm, the weighted average algorithm, and the last found algorithm. A gray scale value is thereby assigned to the defined portion of the output volume. The gray scale value is related to a plurality of gray scale values in the first subset of image information.
There are a number of benefits associated with the imaging method of sorting through all of the image information. The gray scale value for a voxel or toxel in the output volume (or tolume) is determined by using all of the corresponding image information in the input volume. By way of example, image information is not ignored during generation of the output volume. The quality of the image is therefore relatively high. The simultaneous processing of selected image information in all of the scanning planes can also be performed quickly and with the least amount of memory space. Finally, the user has the option of utilizing a number of different algorithms to process the image data in the scanning planes. This flexibility permits the user to select the algorithm producing the highest quality image.
The present invention further includes an ultrasound imaging system for constructing three- or four-dimensional images describing an object. The system preferably includes:
(a) generating means for generating a plurality of image planes, with each image plane containing image information describing the object; and
(b) determining means (e.g., a processor) for determining the image information in each of the plurality of image planes that is within a defined portion of the output volume to define a first subset of image information corresponding to the defined portion in the output volume. The generating means is in communication with the determining means to permit image construction.
The generating means can be any suitable image data acquisition device, such as an ultrasound probe connected to an ultrasound system. A position sensor receiver can be attached to the ultrasound probe to determine the position of the ultrasound probe. By way of example, this can be achieved by an electromagnetic position sensoring system. The generating means can further include a calibration to determine a pixel size of a plurality of pixels in each image plane.
The system can further include analyzing means (e.g., a processor) for analyzing the first subset of image information to define a second set of image information that is derived from the first subset of image information. The second subset of image information is different from the first subset of image information. The analyzing means can assign a gray scale value to the defined portion of the output volume. The gray scale value is preferably related to a plurality of gray scale values in a first set of image information.
In a further embodiment of the present invention, a method is provided for constructing a three- or four-dimensional image describing tissue of a patient using temporal information. The method includes the steps of:
(a) generating image information describing the tissue a
Klein Peter
Marquart Markus
Mumm Bernhard
Casler Brian L.
Patel Maulin
Sheridan & Ross P.C.
Tomtec Imaging Systems GmbH
LandOfFree
Method and apparatus for ultrasound image reconstruction does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for ultrasound image reconstruction, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for ultrasound image reconstruction will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2480075