Ultrasound imaging method and apparatus for forming color images by using a variable power threshold level

• US 6,733,452 B2
• Filed: 04/12/2002
• Issued: 05/11/2004
• Est. Priority Date: 04/13/2001
• Status: Active Grant

• Current Assignee: Medison Co., Ltd. (Samsung Electronics Co. Ltd.)
• Original Assignee: Medison Co., Ltd. (Samsung Electronics Co. Ltd.)
• Inventors: Bang, Ji Hoon, Bae, Moo Ho
• Primary Examiner(s): Jaworski, Francis J.
• Application Number:
  US10/121,351
• Publication Number:
  US 20020165453A1
• Time in Patent Office: 760 Days
• Field of Search: 600/431, 600/440-441, 600/443, 600/447, 600/454-456, 128/916, 736/25--26, 382/128
• US Class Current: 600/443
• CPC Class Codes: G01S 7/52026 Extracting wanted echo signals Doppler systems G01S15/50; Doppler short range imaging systems G01S15/8979
• CPC Class Codes: G01S 7/52071 Multicolour displays; using colour coding; Optimising colour or information content in displays, e.g. parametric imaging

Abstract

An ultrasound imaging method and apparatus forms high-quality color ultrasound images by using variable power threshold levels depending on pixel position. The method comprises the steps of determining a power threshold level that is varied depending on a noise, transmitting ultrasound signals from at least one transducer array to a target object, receiving a first signal including a signal reflected from the target object mixed with a noise, and imaging an ultrasound image of the target object corresponding to the first signal when the power level of the first signal is greater than the variable power threshold level. The apparatus comprises one or more transducers for transmitting an ultrasound signal to an object and receiving a first signal including a reflected signal from the object mixed with a noise; and a digital signal processor for forming an ultrasound image of the object corresponding to the first signal when a power level of the first signal is greater than a variable power threshold level.

Claims

1. An ultrasound imaging method, comprising the steps of:

(a) obtaining a power profile during a predetermined time interval without transmitting an ultrasound signal to a target object and determining a power threshold level on the basis of the power profile, wherein said power threshold level is varied depending on a noise;

(b) transmitting ultrasound signals from at least one transducer array to the target object;

(c) receiving a first signal including a signal reflected from the target object mixed with a noise; and

(d) imaging an ultrasound image of the target object corresponding to said first signal when the power level of said first signal is greater than said variable power threshold level.

2. The method of claim 1, wherein said variable power threshold level is varied depending on each pixel position in said ultrasound image.

3. The method of claim 2, wherein said ultrasound image is a color image.

4. The method of claim 3, wherein the step (a) further comprises the steps of:

receiving a noise corresponding to each scan line within one frame of the color image during the predetermined time interval corresponding to said one frame;

obtaining the power profile of the received noise corresponding to said each scan line by performing an auto-correlation on the received noise; and

determining a power level as greater than a predetermined value than the level of the power profile as said variable power threshold level corresponding to said each scan line.

5. The method of claim 3, wherein the step (a) further comprises the steps of:

receiving a noise corresponding to one scan line within one frame of the color image during the predetermined time interval corresponding to said one frame;

obtaining the power profile of the received noise corresponding to said one scan line by performing an auto-correlation on the received noise; and

determining a power level as greater than a predetermined value than the level of the power profile as said variable threshold level corresponding to all scan lines within said one frame.

6. The method of claim 3, wherein the step (a) further comprises the steps of:

receiving a noise corresponding to one scan line per each scan line group among a plurality of scan line groups within one frame of the color image;

obtaining the power profile of the received noise corresponding to said one scan line per each scan line group by performing an auto-correlation on the received noise; and

determining a power level as greater than a predetermined value than the level of the power profile as said variable threshold level corresponding to said one scan line per each scan line group.

7. The method of claim 3, wherein the step (a) further comprises the steps of:

receiving a noise corresponding to each of all scan lines within the color image during the predetermined time interval corresponding to frames of the same number of said all scan lines, by sequentially acquiring a noise corresponding to one scan line within each of the frames during a time interval corresponding to said each frame of the color image;

obtaining the power profile of the received noise corresponding to said each of all scan lines by performing an auto-correlation on the received noise; and

determining a power level as greater than a predetermined value than the level of the power profile as said variable threshold level corresponding to said each of all scan lines.

8. The method of claim 3, wherein the step (a) further comprises the steps of:

receiving a noise corresponding to one or more scan line within one frame of the color image by using a number of ensembles less than a predetermined number of ensembles, said predetermined number of ensembles being used to form the color image;

obtaining the power profile of the received noise corresponding to said one or more scan line by performing an auto-correlation on the received noise; and

determining said variable power threshold level corresponding to said one or more scan line based on the power profile obtained.

9. An ultrasound imaging apparatus, comprising:

one or more transducer(s) for transmitting an ultrasound signal to a target object;

means for receiving a first signal including a reflected signal from the target object mixed with a noise;

means for measuring a noise power profile by performing an auto-correlation on a noise applied from the receiving means, wherein the noise is obtained at the receiving means during a predetermined time interval when said one or more transducer(s) does not transmit the ultrasound signal to the target object;

means for determining a power threshold level that is varied depending on said noise power profile; and

means for forming an ultrasound image of the target object corresponding to the first signal when a power level of the first signal is greater than said variable power threshold level.

10. The apparatus of claim 9, wherein said variable power threshold level is varied depending on each pixel position in the ultrasound image.

11. The apparatus of claim 10, wherein the ultrasound image is a color image.

12. The apparatus of claim 11, further comprising:

means for controlling the receiving means to receive the noise in order to obtain the noise power profile.

13. The apparatus of claim 12, wherein the control means controls the receiving means to receive the noise corresponding to one or more scan line(s) within one frame of the color image during the predetermined time interval corresponding to said one frame, thereby applying the noise to the measuring means.

14. The apparatus of claim 12, wherein the controlling means controls the receiving means to receive a the noise corresponding to one scan line per each scan line group among a plurality of scan line groups within one frame of the color image, thereby applying the noise to the measuring means, wherein said each scan line group includes one or more scan line(s) having a same aperture of said one or more transducer(s).

15. The apparatus of claim 12, wherein the controlling means controls the receiving means to receive the noise corresponding to each scan line within one frame of the color image by using a number of ensembles less than a predetermined number of ensembles, thereby applying the noise to the measuring means, wherein said predetermined number of ensembles are used to form the color image.

16. A method for obtaining a variable power threshold level in an ultrasound imaging apparatus including one or more transducer(s) for transmitting an ultrasound signal to an object, means for receiving a first signal including a reflected signal from the object mixed with a noise, and means for forming an ultrasound image of the object corresponding to the first signal when a power level of the first signal is greater than said variable power threshold level, comprising the steps of:

a) receiving a noise from said one or more transducer(s) during a predetermined time interval without transmitting the ultrasound signal to the object; and

b) obtaining said variable power threshold level by performing an auto-correlation on the received noise to obtain an auto-correlation value of the received noise.

17. The method of claim 16, wherein said variable power threshold level is varied depending on pixel position in the ultrasound image.

18. The method of claim 16, wherein the step a) further comprises the step of receiving the noise corresponding to each scan line within one frame of the ultrasound image during the predetermined time interval corresponding to said one frame, and

wherein the step b) further comprises the steps of:

obtaining a power profile of the received noise corresponding to said each scan line based on the auto-correlation value; and

determining said variable power threshold level based on the power profile.

19. The method of claim 16, wherein the step a) further comprises the step of receiving the noise corresponding to one scan line within one frame of the ultrasound image during the predetermined time interval corresponding to said one frame, and

wherein the step b) further comprises the steps of:

obtaining a power profile of the received noise corresponding to said one scan line based on the auto-correlation value; and

determining a power level as greater than a predetermined value than the level of the power profile as said variable power threshold level corresponding to all scan lines within said one frame.

20. The method of claim 16, wherein the step a) further comprises the step of receiving the noise corresponding to one scan line per each scan line group among a plurality of scan line groups within one frame of the ultrasound image, and

wherein the step b) further comprises the steps of:

obtaining a power profile of the received noise corresponding to said one scan line per each scan line group based on the auto-correlation value; and

determining a power level as greater than a predetermined value than the level of the power profile as said variable power threshold level corresponding to said one scan line per each scan line group.

21. The method of claim 16, wherein the step a) further comprises the step of receiving the noise corresponding to each of all scan lines within the ultrasound image during a the predetermined time interval corresponding to frames of the same number of said all scan lines, by sequentially acquiring a noise corresponding to one scan line within each of the frames during a time interval corresponding to said each frame of the ultrasound image, and

wherein the step b) further comprises the steps of:

obtaining a power profile of the received noise corresponding to said each of all scan lines based on the auto-correlation value; and

determining a power level as greater than a predetermined value than the level of the power profile as said variable power threshold level corresponding to said each of all scan lines.

22. The method of claim 16, wherein the step a) further comprises the step of receiving the noise corresponding to one or more scan line within one frame of the ultrasound image by using a number of ensembles less than a predetermined number of ensembles, said predetermined number of ensembles are used to form the ultrasound image, and

wherein the step b) further comprises the steps of:

obtaining a power profile of the received noise corresponding to said one or more scan line based on the auto-correlation value; and

determining said variable power threshold level corresponding to said one or more scan line by using the power profile.