Surgery – Truss – Pad
Patent
1990-01-11
1991-12-17
Jaworski, Francis
Surgery
Truss
Pad
12866109, 12866007, A61B 800
Patent
active
050727346
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Filed
The present invention is directed to a pulse Doppler MTI system for equally displaying movement in any directions within a tomographic plane.
2. Background Arts
When a subject for examination undergoes radiation of ultrasound pulses, echoes return from the reflection body. If the reflection body is moving, a frequency of the echoes to be received differs from a transmitting frequency. When the reflection body moves towards a probe, a receiving frequency is higher than the transmitting frequency. Whereas in the case of moving away from the probe, the receiving frequency drops down. A deviation in frequency is proportional to a kinetic velocity of the reflection body. It is possible to detect both a direction in which the blood flows within, e.g., a heart or blood vessels and a flowing speed by utilizing the Doppler effect. The ultrasound pulses are reflected typically from a solid body and from a moving body. Where the attention is paid particularly on the moving body, only reflection signals from the moving body are displayed, while the reflection signals from the solid body are erased. This arrangement facilitates a recognition thereof. For this purpose, there is employed a moving target indicator (hereinafter abbreviated to MTI) system for fetching only the reflection signals coming from the moving body. This type of MTI system has hitherto involved use of an MTI filter, wherein one irradiation ultrasound beam (hereinafter referred to as a sound ray) is dealt with in regards to data on RF signals or equiphase signals (hereinafter referred to as i-signals) of a bipolar video which are obtained by effecting a coherent detection and orthogonal signals (hereinafter referred to as q-signals); and there are grasped variations in time between phasic distributions in an irradiating direction of the ultrasound waves, i.e., in a radial direction. In the case of adopting a multi-beam receiving system, the above-mentioned signal process is merely performed on the respective beams. In an ultrasound diagnosing device for circulatory organs, when measuring a velocity of a blood flow, the direction thereof is limited to the radiant direction, and velocity components can not absolutely be measured with respect to the components right-angled to the sound rays. Hence, it is impossible to accurately measure the flowing velocity. Especially in connection with the blood vessels orthogonal to the sound rays, the flowing velocity and kinetic direction of the blood can not be measured. The accurate measurement of the blood flow requires performing a two-dimensional MTI process in which the components orthogonal to the radiant direction are added as well as processing in the radiant direction.
A video MTI (incoherent MTI) is capable of equally detecting the movements in any directions within a tomographic plane, and hence probably this method can sufficiently be applied. In the MTI after effecting a video detection, however, it is feasible to observe an image of an ambiguous flow in the middle of, e.g., a portal vein. Echoes of the blood flow, or rather the echoes of the blood itself appear as speckle noises, so that there is less chance to obtain a well-shaped image even by indicating an amplitude thereof. Therefore, it is desirable to image-display the signals having a higher fidelity to the development in the form of complex quantities as they are without effecting no video detection.
DISCLOSURE OF THE INVENTION
It is a primary object of the present invention to actualize a pulse Doppler MTI system for equally displaying movements in any directions within a tomographic plane.
The present invention is characterized by the steps of creating a file of bipolar video signals in which receiving signals for one scan serve as one frame on the basis of echo receiving signals of a plurality of scanning processes associated with receive multi-beam forming, and effecting a two-dimensional cross-correlation process after eliminating components relative to fixed reflecting points with respect to data on th
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Jaworski Francis
Kojima Moonray
Manuel George
Yokogawa Medical Systems Limited
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