Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2001-12-12
2003-04-15
Jaworski, Francis J. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S455000, C600S437000, C600S443000, C600S447000, C600S448000, C600S449000, C600S444000, C073S625000, C073S626000, C367S002000, C367S001000
Reexamination Certificate
active
06547733
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an ultrasound imaging apparatus and a method thereof and, more particularly, to an ultrasound imaging apparatus and a method of the same for forming ultrasound images using a set of Golay codes having orthogonal property.
BACKGROUND OF THE INVENTION
An ultrasound imaging apparatus transmits ultrasound signals to an object to be examined and processes signals reflected from the object to provide plane images of the object. It has been widely used in medical apparatuses.
As the power of the ultrasound used in ultrasound imaging apparatuses becomes strong, power of received ultrasound which is scattered or reflected from a medium becomes strong too thereby obtaining excellent signal-to-noise ratio (SNR). Accordingly, if possible, it is advantageous to use ultrasound having great amplitude, i.e., a transmitting wave of high voltage. Consequently, it is desirable to transmit ultrasound having great amplitude and short pulse length.
There is, however, certain limitation of using ultrasound of strong signal power in the application at human body since the ultrasound may influence on the body and also there are some limitations in the system's hardware configuration. In order to resolve those limitations, it is suggested to use ultrasound signals of various code types. Ultrasound of longer length can be transmitted when the ultrasound signal of code type is used. Since the ultrasound of code type is used, the ultrasound of longer length is transmitted. Therefore, the power of instantaneous ultrasound is appropriately adjustable and also more energy is sent, thereby obtaining excellent SNR. Furthermore, received signals are compressed in their lengths by an appropriate signal process thereby obtaining enhanced resolution in the axial direction.
There are some kinds of codes roughly divided into a bi-phase code having 1 and −1, and an arbitrary sequence code having arbitrary values. One can easily construct hardware of an ultrasound transmitter when he/she uses the bi-phase sequence code. Among those bi-phase sequence codes, the Golay code is known for realizing theologically ideal compression.
The Golay code has a set of complementary bi-phase sequences. Here, a predetermined bi-phase sequence set A
i
having M number of sequences with length of L can be represented as follows:
A
i
=[a
i1
,a
2
. . . ,a
iL
] Eq. (1)
wherein i=1,2, . . . ,M, L is the length of the total sequences, and a
i1
,a
i2
, . . . ,a
iL
represent the biphase biphase sequences.
When the above sequence set satisfies the following equation Eq. (2), it is the complementary bi-phase sequence and the complementary bi-phase sequence set can be also used as the Golay code.
∑
i
=
1
M
∑
l
=
1
L
-
k
a
il
a
i
,
l
+
k
*
=
ML
δ
(
k
)
Eq. (2)
wherein k=0,1, . . . ,L−1, and &dgr;(k) represents a general dirac function in which &dgr;(k) is 1 in case of k=0 or &dgr;(k) is 0 in case of k≠0. Herein below, it will be explained about an ultrasound imaging apparatus using a general Golay code.
FIG. 1
is a block diagram of a conventional ultrasound imaging apparatus using Golay codes. As shown in the drawing, the conventional ultrasound imaging apparatus includes: an ultrasound transmitter
100
; an transducer array
110
; a transmitting/receiving switch
120
; an analogue receiver
130
; an A/D converter
140
; a receiving beamformer
150
; a pulse compressor
155
; an echo processor
160
; and a scan converter
170
.
The ultrasound transmitter
100
applies voltage pulse into the transducer array
110
thereby outputting ultrasound signals from each transducer of the transducer array
110
. In particular, each transducer generates ultrasound signals in reaction to the pulses applied from a pulser. While transmitting ultrasound signals, a timing point for generating ultrasound signals can be adjusted at each transducer of the transducer array so that the signals can be transmit-focused at a predetermined point in a region of interest. That is, the pulses are applied from the pulser with time delay into each transducer in order to make the signals to reach the predetermined point simultaneously thereby transmit-focusing at a desired position in the region of interest. As a method for deciding the pattern of transmission delay at each transducer, it has been used a fixed focusing technique which enables to bring a pulse energy of the ultrasound pulse into a predetermined point in a target object. In addition to the above, there has been recently proposed a synthetic aperture method as a suggestion to solve those limitations in resolution, which may be caused by using the fixed focusing technique.
The transmitting/receiving switch
120
acts for protecting the analogue receiver
130
from high voltage emitted from the ultrasound transmitter
100
. In other words, the transmitting/receiving switch
120
switches properly the ultrasound transmitter
100
and the analogue receiver
130
while the transducer performs receiving and transmitting in turns.
The transducer array
110
has a plurality of transducers, for example
128
transducers, and each transducer reacts to a voltage applied from the ultrasound transmitter
100
and outputs ultrasound pulses. The fixed focusing technique or the synthetic aperture method as aforementioned can be used for such transmitting method. Herein, only some of the plurality of transducers are used for transmission of a time. In the fixed focusing technique, although an imaging apparatus includes
128
transducers, for example, only
64
transducers of them within a selected aperture transmit at one transmission of the ultrasound signals to a target object thereby forming one scan line.
The analogue receiver
130
receives reflected signals of ultrasound pulses returning from the object, in which the ultrasound pulses are outputted from each transducer of the transducer array
110
; and also transmits processed signals into the A/D converter
140
, in which the received reflected signals are amplified, removed the aliasing phenomenon and noise components, and attenuates equalization caused while the ultrasound passes through internal body. The A/D converter
140
converts an analogue signal from the analogue receiver
130
to a digital signal, and provides the digital signal to the receiving beamformer
150
. The receiving beamformer
150
performs a dynamic receive-focusing by applying various amounts of delay, which vary with locations of the receive-focusing, to signals received from the A/D converter
140
and synthesizes the delayed signals.
The pulse compressor
155
processes the signals received from the receiving beamformer
150
in order to obtain resolution having similar quality as that of an ultrasound imaging apparatus of short pulse type. In the ultrasound imaging apparatus using long code like the Golay code, pulse compression is necessary because side-lobes of the received signals at the receiving beamformer
150
are too large to consist an image.
The echo processor
160
changes the pulse-compressed signals of the pulse compressor
155
into baseband signals, and extracts an envelope by using a quadrature demodulator, thereby obtaining data of a scan line.
The scan converter
170
stores the data obtained from the echo processor
160
in a memory (not shown), and matches a scan direction of the stored data to a pixel direction of a monitor. Meanwhile the data is mapped out at its corresponding pixel position on a monitor.
FIG. 2
illustrates an ultrasound transmitting process in the conventional ultrasound imaging apparatus as shown in FIG.
1
. For convenience of explanation, the drawing only exemplifies a Golay code including a code sequence set of A
1
, A
2
having length of L and M=2, and transmission by focusing at one focal point P.
In a first ultrasound transmission at one pulse repetition interval (PRI), all array elements
1
a
~
1
h
within a predetermined aperture of the
Hwang Jae Sub
Song Tai Kyong
Carlson Dale L.
Jaworski Francis J.
Kinney Michael K.
Medison Co. Ltd.
Patel Maulin
LandOfFree
Ultrasound imaging apparatus and method using Golay codes... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ultrasound imaging apparatus and method using Golay codes..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ultrasound imaging apparatus and method using Golay codes... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3037023