Ultrasonic signal focusing method and apparatus for ultrasonic imaging system

• US 6,231,511 B1
• Filed: 11/10/1998
• Issued: 05/15/2001
• Est. Priority Date: 11/10/1997
• Status: Expired due to Term

• Current Assignee: Medison Co., Ltd. (Samsung Electronics Co. Ltd.)
• Original Assignee: Medison Co., Ltd. (Samsung Electronics Co. Ltd.)
• Inventors: Bae, Moo-Ho
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): Imam, Ali M.
• Application Number:
  US09/189,690
• Time in Patent Office: 917 Days
• Field of Search: 600/443, 600/447, 600/437, 600/444, 600/440, 600/441, 128/916, 367/7, 367/11, 367/138, 736/02, 735/97
• US Class Current: 600/447
• CPC Class Codes: G01S 7/52046 Techniques for image enhancement involving transmitter or receiver image enhancement by image data processing G06T5/00
• CPC Class Codes: G01S 7/52049 using correction of medium-induced phase aberration
• CPC Class Codes: G10K 11/346 using phase variation

Abstract

An ultrasonic signal focusing method and apparatus is provided, in which an ultrasonic signal reflected from an object is focused at all points from and to which transmission and reception are performed on a scan line. The ultrasonic signal focusing method includes an ultrasonic signal transmission step for moving, focusing and transmission-scanning the transmission scan line in turn, using an array transducer, an ultrasonic signal reception step for receiving all the ultrasonic signals transmitted along the scan lines at the transducer elements which are placed in the location at which reception is enabled, an ultrasonic storing step for storing all the received ultrasonic signals by each scan line, and an ultrasonic focusing step for interpolating an arrival delay amount of the ultrasonic signals stored after arrival at a different point in time and summing the interpolated signal. Thus, all the signals obtained by performing transmission focusing on a number of adjacent scan lines are used to thereby perform reception focusing, to thereby provide the same effect as the case where focal points exists in all the points on the scan line.

Claims

1. An ultrasonic signal focusing method using an array transducer, the method comprising the steps of:

transmitting from the array transducer ultrasound signals;

receiving the ultrasound signals returning to a transducer element; and

obtaining an ultrasonic focusing signal corresponding to each point on a particular scan line, using an ultrasonic signal obtained from each point on the particular scan line and ultrasonic signals obtained from each point on the particular scan line by different transmission scan lines adjacent to the particular scan line.

2. The ultrasonic signal focusing method according to claim 1, wherein said ultrasonic focusing signal obtaining step comprises:

(a) an ultrasonic signal transmission step for moving, focusing and transmission scanning the transmission scan line in turn;

(b) an ultrasonic signal reception step for receiving all the ultrasonic signals transmitted along the scan lines at the transducer elements which are placed in the location at which reception is enabled;

(c) an ultrasonic storing step for storing all the received ultrasonic signals by each scan line; and

(d) an ultrasonic focusing step for interpolating an arrival delay amount of the ultrasonic signals stored after arrival at a different point in time and summing the interpolated signal.

3. The ultrasonic signal focusing method according to claim 2, wherein said step (d) calculates a focusing delay amount considering a delay time returning to the respective transducer elements after the transmission focused and transmitted signal reaches the final focal point.

4. The ultrasonic signal focusing method according to claim 3, wherein said focusing delay amount t_d(t, x_f, Z_f, x_e) is calculated by the following equation in order to be added to the received signal to reinforce the reference signal from the target point on the transmission scan line, $t_d$

(t,Xf,Zf,Xe)=t-[Zf-(Zf-(υ



 



t/2))2+Xf2υ

+(υ



 



t/2)2+Xe2υ

]

wherein the transmission scan line passes through the point (X_f,

     0), the coordinate of the focal point is (X_f, Z_f), the coordinate of the receiving transducer element is (X_e,

     0), the finally focused scan line passes through the origin (0,

     0), and the length of the path travelling from the target point to the surface of the transducer element is vt/2.

5. The ultrasonic signal focusing method according to claim 4, wherein said focusing delay amount t_d(t, X_f, Z_f, X_e) is added to the signals of all the transducer elements with respect to all the transmission operations, and then all the added signals are summed and focused.

6. The ultrasonic signal focusing method according to claim 5, wherein the final focusing signal through adding said focusing delay amount, summing and focusing the added result, is calculated by the following equation, $S_{\mathrm{focused}}$

(t)=∑

Xe

∑

Xf

(A

(t,Xe,Xf)·

s

(t-td

(t,Xf,Zf,Xe),Xf,Xe,Xf))

in which A(t,X_e,X_f) uses a respective appropriate function according to t, X_e, and X_f, and t is set to 0 every time when transmission is performed.

7. An ultrasonic focusing apparatus for focusing ultrasonic signal, comprising:

an array transducer configured to have a different time delay in a transducer element located at a different place from each other, for performing lateral transmission focusing;

a reception portion for appropriately amplifying the ultrasonic signal returning to the transducer element and converting the amplified result into a digital signal;

an intra-channel processing portion for separate storing signals received from the reception portion receiving ultrasonic signals returning from a desired point, and separately storing the ultrasonic signals corresponding to each scan line every time when the received signals are transmitted, calculating a time delay to be applied to the stored ultrasonic received signals and focusing signals on various transmission scan lines in a single transducer element to correspond to all the transducer elements and outputting the focused signals; and

a reception focusing portion for summing outputs of the intra-channel processing portion and completing a focusing operation using the signals output from all the transducer elements.

8. The ultrasonic signal focusing apparatus according to claim 7, wherein said reception focusing portion comprises:

an intra-channel apodization value calculator for calculating a respective intra-channel apodization value;

a multiplier for performing a multiplication operation of the signal applied from said intra-channel processing portion according to the apodization value applied from said intra-channel apodization value calculator; and

an adder for adding the signal output from said multiplier and outputting the final focused value.

9. The ultrasonic signal focusing apparatus according to claim 7, wherein said intra-channel processing portion comprises:

a number of buffer memories for storing radio frequency (RF) data converted into a digital signal from the received ultrasonic signal, according to a respective scan line;

a write controller for outputting a control signal to store the RF data in the buffer memory;

a focusing delay amount calculator for calculating a focusing delay time to focus the RF data stored in the buffer memory;

a read controller for outputting a control signal to read the ultrasonic signal stored in the buffer memory according to a read address applied from the focusing delay amount calculator;

a delay interpolator for interpolating the signal according to the focusing delay amount calculated in said focusing delay amount calculator and delaying the signal by an accurate amount; and

an apodization portion for applying a weight value to the signal delayed from said delay interpolator, and adding the weight applied signals.

10. The ultrasonic signal focusing apparatus according to claim 9, wherein said apodization portion comprises:

an intra-channel apodization value calculator for calculating the apodization value;

a multiplier for multiplying the signal applied from said intra-channel processing portion by an appropriate weight value according to the apodization value applied from said intra-channel apodization value calculator; and

an adder for adding all the signals output from said multiplier and outputting a value for which an apodization is performed with respect to a scan line.