Surgery – Truss – Pad
Patent
1989-10-23
1991-05-28
Jaworski, Francis
Surgery
Truss
Pad
7386125, A61B 806
Patent
active
050185284
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement of a pulse Doppler ultrasonic diagnostic system.
2. Description of the Prior Art
A pulse Doppler ultrasonic diagnostic system is intended to obtain a kinetic direction and a velocity of a ultrasonic scatterer by extracting only ultrasonic scattering signals from a region of concern within a subject for examination by processing Doppler shift components. In order to fetch the ultrasonic signals from the region, signals from an interval .DELTA.x between a depth x and a depth x+.DELTA.x have to be accumulated in any form and sample-held. The accumulation of signals involves the use of a method of integrating reflection signals with transmit ultrasonic waves serving as single pulse waves for a period equivalent to a sample volume length .DELTA.y by use of an interval integrator, or alternatively a method of sample-holding the reflection signal with the transmit ultrasonic waves serving as burst waves, the number of waves corresponds to the interval .DELTA. after a given time has passed, with a wave transmitting time being defined as an origin. Mean power of the transmit ultrasonic waves is limited to a constant value or under in terms of security in connection with influences of the ultrasonic waves on a human body. Under such a condition that the mean power is restricted to the constant value, however, it is impossible to invariably obtain best Doppler signals with respect to an arbitrary sample volume length simply by employing any one of the above-mentioned methods.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide a pulse Doppler ultrasonic diagnostic system capable of obtaining the best Doppler signals with respect to an arbitrary sample volume length under a condition that mean power of transmit ultrasonic waves is limited to a constant value.
To accomplish this object, according to one aspect of the invention, there is provided a pulse Doppler ultrasonic diagnostic system comprising: a means for making mean power constant in connection with transmit ultrasonic signals; a means for making the number of burst waves variable; and a means for making an integration interval variable in connection with ultrasonic receiving signals, characterized in that best Doppler signals are obtained by controlling both the number of burst waves of the transmit ultrasonic waves and the integration interval of the ultrasonic receiving signals.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages of the present invention will become apparent during the following discussion taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a block diagram depicting a conceptual construction of one embodiment of the present invention;
FIG. 2 is a graph showing variations in Doppler outputs versus the number of burst waves when setting constant a wave transmit central frequency and a sample volume length; and
FIG. 3 is a graph showing variations in degree of improvement of the Doppler outputs with respect to the sample volume length when controlling the number of burst waves and a time integration interval length.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An illustrative embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings. Referring first to FIG. 1, the numeral 1 represents a controller for outputting control signals corresponding to a pulse repeating frequency (hereinafter abbreviated to PRF), a sample volume depth (SVD), a sample volume length (SVL) and a transmit central frequency (fo) which are set from outside. Designated at 2 is a transmit wave generating circuit for generating high frequency signals upon receiving the control signals relative to the number of burst waves, a PRF and a transmit central frequency from the controller 1, and further outputting the generated high frequency signals to a driver 3. The driver 3 in turn outputs the high frequency signals by power-amplifying them after recei
REFERENCES:
patent: 4819652 (1989-04-01), Micco
patent: 4848356 (1989-07-01), Nakamura et al.
Higashiizumi Takao
Hirota Yuichi
Morita Dai
Jaworski Francis
Kojima Moonray
Yokogawa Medical Systems Limited
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