Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-03-01
2001-07-10
Vo, Peter (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C128S916000
Reexamination Certificate
active
06258030
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ultrasonic diagnostic apparatus. The invention relates more particularly to a technique for reducing cost and power consumption of a three-dimensional diagnostic apparatus by decreasing the number of delay circuits used for forming reception beams, in the three-dimensional diagnostic apparatus for obtaining a real-time three-dimensional image by three-dimensionally scanning a human body by applying ultrasonic beams thereto.
2. Description of the Background Art
(1) Two-dimensional ultrasonic diagnostic apparatus Conventionally, there has been known an ultrasonic diagnostic apparatus for obtaining a two-dimensional tomogram of a subject such as a human body.
FIG. 1
shows a part of a conventional two-dimensional ultrasonic diagnostic apparatus. This two-dimensional ultrasonic diagnostic apparatus employs a one-dimensional array probe
101
having a plurality of fine transducers
100
arranged in one row as shown in FIG.
1
.
The operation of the two-dimensional ultrasonic diagnostic apparatus will be explained below.
At the time of transmitting ultrasonic beams from the two-dimensional ultrasonic diagnostic apparatus, a transmission electric signal is supplied to each transducer
100
through a delay circuit provided for each transducer
100
. When each transducer
100
has received this transmission electric signal, each transducer
100
is driven, and ultrasonic beams are being sent from the transducer
100
. By changing the delay time of each delay circuit, beam directions to a focus F of the ultrasonic beams can be changed as shown by solid lines and a dotted line in FIG.
1
. The conventional two-dimensional ultrasonic diagnostic apparatus is structured to scan a subject by the ultrasonic beams in a desired direction by arbitrarily changing the delay time set in each delay circuit.
On the other hand, at the time of receiving ultrasonic beams in the two-dimensional ultrasonic diagnostic apparatus, each transducer
100
detects a reflection wave (echo) reflected from the focus F.
FIG. 2
shows a structure of the two-dimensional ultrasonic diagnostic apparatus. Each detection signal detected by the transducer
100
is delay processed with a predetermined delay time by a delay circuit
102
shown in FIG.
2
. By this delay processing, phases of the detection signals corresponding to the focus F are matched. The detection signals after the phase matching are added together by an adder circuit
103
to be formed as a reception signal. This signal is then supplied to an image processing circuit. The image processing circuit executes a predetermined image processing to reception signals to reconstruct a two-dimensional tomogram and displays it in a display. With the above-described processing, it is possible to obtain a two-dimensional tomogram of a subject. The above-described two-dimensional ultrasonic diagnostic apparatus requires the delay circuits
102
by the number of the transducers
100
for simultaneously receiving reflection waves. These delay circuits are combined with the ultrasonic transducers to converge the ultrasonic beams into the focus F, and at the same time, controls the scanning direction of the ultrasonic beams and directivity of each transducer as a sensor.
Next, according to the conventional ultrasonic diagnostic apparatus, there has been put into practical use a so-called real-time display for displaying images obtained in real time from ultrasonic waves. To achieve this real-time display, it is necessary to display images of 10 to 30 frames every second. For reconstructing these large number of frame images, there is required information of a large number of scanning lines that comprise the frames. As one of methods for a real-time display, there is “parallel simultaneous reception processing”. This parallel simultaneous reception processing is a method for obtaining information of a plurality of scanning lines in one-time transmission of ultrasonic wave. To be more specific, a plurality of scanning lines whose directivity mutually differ are set within the ultrasonic wave to be transmitted, and a plurality of reception signals along these scanning lines are formed, synthesized and signal-processed thereby so as to reconstruct ultrasonic tomographic images on the plurality of scanning lines.
FIG. 3
shows a structure of the two-dimensional ultrasonic diagnostic apparatus for carrying out the parallel simultaneous reception processing. Steps of the parallel simultaneous reception processing will be explained with reference to FIG.
3
.
In the parallel simultaneous reception processing, a plurality of delay circuits
102
are provided in one reception channel
105
corresponding to one transducer
100
as shown in FIG.
3
. By setting different delay times for these delay circuits
102
, a plurality of detection signals with different phases are formed. Next, of the detection signals from the delay circuits
102
of the respective reception channels
105
, detection signals of the same phase are added together by the adder circuit
103
, so that a plurality of reception signals are formed. By reconstructing these reception signals, one ultrasonic tomographic image is obtained.
The above-described parallel simultaneous reception processing requires the delay circuits as follows:
the number of delay circuits=the number of the transducers×the number of parallel simultaneous receptions
In this case, the number of ultrasonic transducers is equal to the number of reception channels. The number of parallel simultaneous receptions is equal to the number of scanning lines per one reception channel.
In general, the number of reception channels held by the two-dimensional ultrasonic diagnostic apparatus is about 100, while the number of parallel simultaneous reception is about four. Accordingly, the number of delay circuits required by the two-dimensional ultrasonic diagnostic apparatus is:
100 channels×4=about 400
(2) Three-dimensional ultrasonic diagnostic apparatus
A three-dimensional ultrasonic diagnostic apparatus will be explained next. There has been an attention focussed on the three-dimensional ultrasonic diagnostic apparatus in recent years. The three-dimensional ultrasonic diagnostic apparatus employs a two-dimensional array probe having a plurality of rows of array probes, each row having a plurality of transducers arranged in one row. With this two-dimensional array probe structure, a subject is scanned three-dimensionally by applying ultrasonic beams to obtain a three-dimensional image of the subject. Since this three-dimensional ultrasonic diagnostic apparatus has the array probe arranged two-dimensionally, it is necessary to process detection signals output from in excess of 1000 transducers. At the same time, the number of scanning lines required becomes enormous for reconstructing a three-dimensional image by carrying out a three-dimensional scanning. Therefore, in the three-dimensional ultrasonic diagnostic apparatus, the above-described parallel simultaneous reception processing becomes inevitable for obtaining a plurality of scanning lines in one transmission, particularly in the case of carrying out a real-time display.
In this three-dimensional ultrasonic diagnostic apparatus, the number of delay circuits required for carrying out the above parallel simultaneous reception processing is obtained by the following formula, in a manner similar to that of the two-dimensional ultrasonic diagnostic apparatus:
the number of delay circuits=the number of the transducers×the number of parallel simultaneous receptions
To be more specific, in the three-dimensional scanning, the two-dimensional array probe structure requires thereception channels by the number of at least 32 channels×32 channels, for reducing the artifact to a practical level. In this case, the number of the parallel simultaneous receptions becomes 4×4. Accordingly, the three-dimensional ultrasonic diagnostic apparatus requires an enormous large number
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Patel Maulin
Vo Peter
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