Surgery – Truss – Pad
Patent
1994-07-18
1996-03-05
Jaworski, Francis
Surgery
Truss
Pad
A61B 800
Patent
active
054958466
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an ultrasonic diagnostic apparatus having an inter-frame averaging function improved in its averaging characteristic.
BACKGROUND ART
An ultrasonic diagnostic apparatus is such that transmits an ultrasonic signal from its ultrasonic probe into an examined body, receives the signal echoing from tissues or a diseased part of the examined body, and displays a tomographic image formed from the echo signal on a CRT for diagnostic use.
In such an ultrasonic diagnostic apparatus, in the case where the frame rate is low, i.e., where the interval is large between the periods in which the ultrasonic wave is transmitted, if the change between the signal received one frame before and the signal currently received is great, there is produced a flicker on the CRT screen. In order to improve the situation, a method called an inter-frame averaging process to average the previous and current data has been in use.
In the inter-frame averaging process which has so far been in practice, arithmetic averaging of the previous frame data and the current frame data has been performed using a constant arithmetic-averaging coefficient at all times. Accordingly, there have been such problems that, when the examined object is a moving reflector such as a valve of the heart and a flow of blood or when the ultrasonic wave is transmitted and received while the ultrasonic probe is being moved, the characteristic of the apparatus to follow up an image of an internal organ or the like is deteriorated and an afterimage is produced. If the weighting with the arithmetic-averaging coefficient .omega. is lightened to improve the situation, a difficulty arises that noises increase and a flickering view is produced.
On the other hand, there has been a method in which the absolute value of the differential between the old data and the new data is taken and the value of .omega. is varied according to the absolute value and such a variable value of .omega. is used in an arithmetic averaging process. In this method, while the arithmetic-averaging coefficient .omega. is varied for each frame according to a detected movement of the echoing part, the averaging process for the entire object becomes lighter when there is a moving part in the image and, hence, the averaging process for the portion where there is no movement also becomes lighter and such a difficulty arises that noises cannot be sufficiently removed.
DISCLOSURE OF THE INVENTION
The present invention was made in view of the above situations. An object of the invention is to realize an ultrasonic diagnostic apparatus which detects moving and stationary portions within the same frame, selects a suitable arithmetic-averaging coefficient for each of the portions, and thereby, while improving its characteristic to follow up the image, secures a sufficient noise removing capability.
In order to solve the above mentioned problems, the invention is characterized in that it comprises: previous occasion; as the absolute value of the difference between new data, which are signals currently inputted thereto, and old data read from the frame memory for calculating arithmetic-averaging coefficients ".omega." and "1-.omega." as weighting functions, which are functions of the new data or the old data and the differential data; coefficient "1-.omega." outputted from the weighting function generator; from the frame memory by the coefficient ".omega." outputted from the weighting function generator; and data of the old data multiplier.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing an apparatus as an embodiment of the invention.
FIG. 2 is a flowchart of operations of the apparatus of the embodiment.
FIG. 3 is a graph showing values of the weighting function relative to the values of new data and differential data.
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram showing an apparatus as an embodime
REFERENCES:
patent: 4761740 (1988-08-01), Lipschutz
patent: 5083566 (1992-01-01), Baba
patent: 5215093 (1993-06-01), Miyazaki et al.
patent: 5318033 (1994-06-01), Savord
Morita Dai
Uehara Shoichi
GE Yokogawa Medical Systems Limited
Jaworski Francis
Kojima Moonray
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