Surgery – Truss – Pad
Patent
1987-05-18
1988-07-26
Jaworski, Francis J.
Surgery
Truss
Pad
7386125, A61B 1000
Patent
active
047593733
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a pulse Doppler apparatus of a phased array system usable as medical ultrasonic equipment or a short-range sonar, and more particularly to an improvement in a method of forming a received ultrasonic beam.
2. Background Art
A conventional type of phased-array Doppler apparatus is normally provided in a form capable of being also used as and combined with a B-mode imaging device. Therefore, not only a probe but an initial-stage amplifier and a received-beam former (referred to also as "phase converter") are commonly used for the purpose of both imaging and Doppler processings.
FIG. 8 shows an example of a apparatus of this conventional type. As shown in FIG. 8, an array probe 1 is driven by a pulse at a high voltage supplied by a transmitter/receiver circuit group 2, and transmits ultrasonic waves into a body organ. The transmitter/receiver circuit group includes high-voltage pulse generating circuits each corresponding to each element of the probe 1. The respective high-voltage pulse generating circuits are driven by a plurality of outputs from a transmitted-beam former 3. The transmitted-beam former 3 receives an output trigger pulse from a transmission trigger circuit 4, and outputs a plurality of output signals which are appropriately time-delayed, respectively. The transmission trigger circuit 4 is triggered by a signal obtained by dividing the frequency of a clock of a clock generator 6 by means of a frequency divider 5.
The probe 1 converts echoes from body organs into electrical signals, and outputs them. The echo signals converted into electrical signals pass through the initial-stage amplifiers of the transmitter/receiver circuit group 2, and are input to a received-beam former 7. In the received-beam former 7, after completion of phase matching, the echo signals are added and supplied as an output. This echo signal is supplied to a B-mode imaging echo filter 8 and a Doppler echo filter 9. The output from the echo filter 8 is passed through a logarithm compression RF amplifier 10, then detected by a detector 11 and supplied as a B-mode video signal. This video signal is input to a B-mode display device (not shown) on which a B-mode image display is produced.
The output from the Doppler echo filter 9 is conducted into a coherent detector 12 in which only a Doppler signal relative to a transmitted spectrum is extracted in response to 90.degree. out-of-phase reference waves supplied from a phase converter 13. The phase converter 13 uses as a carrier a clock of the clock generator 6 and outputs 90.degree. out-of-phase reference waves. The echo signal is divided into two channels by the coherent detector 12, and the echo signals through the respective channels are gated by a range gate 14. Subsequently, only a signal in an effective frequency range is extracted in a Doppler filter 15, and is subjected to a Nyquist filter 16.
The range gate 14 is a gate for selecting a Doppler signal from within a given sample volume belonging to an object depth, and a signal for controlling the gate is supplied by a range gate setter 17. The range gate setter 17 generates a range gate signal RG on the basis of an output from the transmission trigger circuit 4.
A Doppler AF signal output from the Nyquist filter 16 is supplied to a frequency analyzer (not shown), and is analyzed therein. The result of the analysis is displayed on a display device (not shown). Also, the Doppler AF signal can be directly monitored as an audio sound through a loudspeaker or the like.
Echoes containing a Doppler shift from body organs are extremely weak as compared with echoes containing no Doppler shift. Typically, echoes from a blood stream is about 30dB lower than echoes from a surrounding body tissue. The echoes from the blood stream are commonly superimposed on those from the surrounding body tissue. Therefore, in order to positively pick up the former echoes, the signal processing circuit employed requires a wide dynamic range and superior linearity.
In a conventional syst
REFERENCES:
patent: 4182173 (1980-01-01), Papadofrangakis et al.
patent: 4509525 (1985-04-01), Seo
patent: 4598589 (1986-07-01), Riley
patent: 4598716 (1986-07-01), Hileman
patent: 4640292 (1987-02-01), Tykulsky et al.
Jaworski Francis J.
Kojima Moonray
Yokogawa Medical Systems Limited
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