Method and system for controlling ultrasound scanning sequence

Abstract

The sequence for a case of scanning by an ultrasound prove having a plurality of transducers, for example, m numbers, is as follows: first scan line→(m-l)th scan line→mth scan line→first scan line→second scan line→mth scan line→first scan line→second scan line→third scan line→first scan line→. . . The ultrasound probe transmits ultrasound beams to a subject and receives echo signals reflected from the subject in accordance with the above sequence. Doppler signals obtained from the echo signals are stored in a memory. When the predetermined number of Doppler signals in each line are stored in the memory, the Doppler signals in each line are read out from the memory. By such scanning sequence, a repeat frequency, i.e., a sampling frequency of Doppler signals of the ultrasound beams transmitted in the same direction, is a shorter. As a result, a low limit of measurable flow velocity is a lower, and a timing for reading out (outputting) the Doppler signals from the memory can be a constant.

What is claimed is: 
     
       1. A method for controlling an ultrasound scanning sequence, the method comprising the steps of: setting a number of ultrasound beams transmitted to a subject in a same direction;   setting a detection ratio used for detecting a flow velocity of the subject; and   controlling the ultrasound scanning sequence in accordance with the number of ultrasound beams and the detection ratio, so as to increase a transmission interval of the ultrasound beams in the same direction without changing a generation interval of an ultrasound pulse.   
     
     
       2. A method according to claim 1, wherein the detection ratio P is obtained by the following equation:   P=ƒr'/ƒr     where fr is a frequency corresponding to a transmission interval of the ultrasound beams in the same direction and fr' is the frequency corresponding to the generation interval of ultrasound pulse.   
     
     
       3. A method as in claim 1, wherein said controlling step includes the steps of, in sequence: (a) commanding transmitting an ultrasound beam to the subject in a first direction;   (b) commanding transmitting ultrasound beams to the subject in .Iadd.a number of .Iaddend.additional directions, .[.including a second direction through a direction having a number.]. .Iadd.whereby a total number of said number of additional directions and said first direction is .Iaddend.equal to said detection ratio; and   (c) repeating said steps (a) and (b) a number of times equal to .[.said generation interval.]. .Iadd.a number of times a sample is taken in each direction.Iaddend..   
     
     
       4. A system for controlling an ultrasound scanning sequence, the system comprising: transmitting means for transmitting ultrasound beams to a subject;   receiving means for receiving echo signals from the subject;   processing means for processing echo data representing the received echo signals to obtain a flow velocity;   storing means for storing the echo data; and   control means for controlling the transmitting means, the receiving means and the storing means in accordance with the ultrasound scanning sequence, so as to increase a transmission interval of the ultrasound beams in the same direction without changing a generation interval of an ultrasound pulse.   
     
     
       5. A system according to claim .[.4.]. .Iadd.6.Iaddend., wherein the detection ratio P is obtained by the following equation:   P=ƒr'/ƒr     where fr is the frequency corresponding to the transmission interval of the ultrasound beams .Iadd.in the same direction .Iaddend.and fr' is the frequency corresponding to the general interval of .Iadd.the .Iaddend.ultrasound pulse.   
     
     
       6. A system according to claim .[.5.]. .Iadd.4.Iaddend., wherein the control means includes: first setting means for setting a number or ultrasound beams transmitted to a subject in the same direction:   second setting means for setting a detection ratio used for detecting a flow velocity or the subject; and   generating means for generating control signals for controlling the ultrasound scanning sequence by the number set by the first setting means and the detection ratio set by the second setting means.   
     
     
       7. A system as in claim .[.3.]. .Iadd.6.Iaddend., wherein said control means includes means for, in sequence: (a) controlling the transmitting means to transmit an ultrasound beam to the subject in a first direction;   (b) controlling the transmitting means to transmit ultrasound beams to the subject in a .Iadd.number of .Iaddend.additional .[.direction, including a second direction through a direction.]. .Iadd.directions, whereby a total number of said number of additional directions and said first direction is .Iaddend.equal to said detection ratio; and   (c) repeating said steps (a) and (b) a number of times equal to .[.said generation interval.]. .Iadd.a number of times a sample is taken in each direction.Iaddend.. .Iadd.   
     
     
       8.  A method according to claim 3, further comprising the steps of: transmitting the ultrasound beams so as to cause echo signals to be echoed from the subject;   receiving the echo signals;   generating echo data corresponding to the received echo signals;   storing the echo data; and   reading out the stored data, corresponding to the received echo signals from each direction, at non-equal intervals..Iaddend..Iadd.   
     
     
       9.  A method according to claim 1, wherein said controlling step comprises in sequence the steps of: (a) commanding transmitting ultrasound beams to the subject in several directions of a predetermined number of directions in an interleaved fashion, until a predetermined number of samples are taken in each direction; and   (b) repeating said step (a) until the ultrasound beams are transmitted to all predetermined directions. .Iaddend..Iadd.   
     
     
       10.  A system according to claim 7, wherein the control means controls the ultrasound scanning sequence so that the stored echo data, corresponding to the received echo signals from each direction, is read out from the storing means at non-equal intervals. .Iaddend..Iadd. 
     
     
       11.  A system according to claim 4, wherein said control means comprises means for changing direction of the transmitted ultrasound beams in a fashion interleaved in each of several directions. .Iaddend..Iadd. 
     
     
       12.  A method for controlling an ultrasound scanning sequence, the method comprising the steps of: setting a number of ultrasound beams to be transmitted to a subject in a same direction;   setting a detection ratio used for detecting a flow velocity of the subject;   controlling the ultrasound scanning sequence in accordance with the number of ultrasound beams and the detection ratio, so as to increase a transmission interval of the ultrasound beams in the same direction without changing a generation interval of an ultrasound pulse by commanding the transmission of ultrasound beams to the subject in a number of additional directions;   transmitting the ultrasound beams so as to cause echo signals to be echoed from the subject;   receiving the echo signals;   generating output data corresponding to the received echo signals from each direction at equal intervals. .Iaddend..Iadd.   
     
     
       13.  A method according to claim 12, wherein said output data corresponding to the received echo signals from each direction is generated at equal intervals which are larger than 1/fr', where fr' is a frequency corresponding to the generation interval of the ultrasound pulse. .Iaddend..Iadd. 
     
     
       14.  A method according to claim 13, wherein said intervals are equal to n/fr', where n is a number of received echo signals from each direction. .Iaddend..Iadd.15. A method for controlling an ultrasound scanning sequence, the method comprising the steps of: setting a number of ultrasound beams to be transmitted to a subject in a same direction;   setting a detection ratio used for detecting a flow velocity of the subject;   controlling the ultrasound scanning sequence in accordance with the number of ultrasound beams and the detection ratio, so as to increase a transmission interval of the ultrasound beams in the same direction without changing a generation period of an ultrasound pulse by commanding the transmission of ultrasound beams to the subject in a number of additional directions;   transmitting the ultrasound beams so as to cause echo signals to be echoed from the subject;   receiving the echo signals;   generating output data corresponding to the received echo signals from each   
     
     
        direction at non-equal intervals. .Iaddend..Iadd.16.  A method according to claim 15, wherein said output data corresponding to the received echo signals from each direction is generated repeatedly at a first interval (n-1)/fr' and a second interval (n+1)/fr', where fr' is a frequency corresponding to the generation period of the ultrasound pulse and n is a number of the received echo signals from each direction. 
     
     
        .Iaddend..Iadd.     A system for controlling an ultrasound scanning sequence, the system comprising: transmitting means for transmitting ultrasound beams to a subject in a number of directions in an interleaved fashion, so as to cause Doppler-shifted echo signals to be echoed from the subject;   receiving means for receiving the Doppler-shifted echo signals until a predetermined number of Doppler-shifted echo signals are received from each of the several directions;   generating means for generating output data corresponding to the received Doppler-shifted echo signals; and   control means for controlling the transmitting means and the receiving means in accordance with the ultrasound scanning sequence, so as to generate the output data corresponding to the received Doppler-shifted   
     
     
        echo signals from each directions at equal intervals. .Iaddend..Iadd.18. A system according to claim 17, wherein said output data corresponding to the received echo signals from each direction is generated at equal intervals which are larger than 1/fr', where fr' is a frequency corresponding to the generation interval of the ultrasound pulse. .Iaddend..Iadd.19. A system according to claim 18, wherein said intervals are equal to n/fr', where n is a number of the received echo signals from each direction. .Iaddend..Iadd.20. A system for controlling an ultrasound scanning sequence, the system comprising: transmitting means for transmitting ultrasound beams to a subject in a number of directions in an interleaved fashion, so as to cause Doppler-shifted echo signals to be echoed from the subject;   receiving means for receiving the Doppler-shifted echo signals until a predetermined number of Doppler-shifted echo signals are received from each of the several directions;   generating means for generating output data corresponding to the received Doppler-shifted echo signals; and   control means for controlling the transmitting means and the receiving means in accordance with the ultrasound scanning sequence, so as to generate the output data corresponding to the received Doppler-shifted echo signals from each direction at non-equal intervals. .Iaddend..Iadd.21. A system according to claim 20, wherein said output data corresponding to the received echo signals from each direction is generated repeatedly at a first interval (n-1)/fr' and a second interval (n+1)/fr', where fr' is a frequency corresponding to a generation period of an ultrasound pulse and n is a number of the received echo signals from   
     
     
        each direction. .Iaddend..Iadd.22.  A method for controlling an ultrasound scanning sequence, the method comprising the steps of: (a) transmitting ultrasound beams to a subject in several directions in an interleaved fashion and receiving Doppler-shifted echo signals until a predetermined number of Doppler-shifted echo signals are received from each of the several directions; and   (b) switching directions of transmission of the ultrasound beams to other several directions. .Iaddend..Iadd.23. A system for controlling an ultrasound scanning sequence, the system comprising:   transmitting means for transmitting ultrasound beams to a subject in several directions in an interleaved fashion and receiving Doppler-shifted echo signals until a predetermined number of Doppler-shifted echo signals are received from each of the several directions; and   switching means for switching directions of transmission of the ultrasound beams to other several directions. .Iaddend..Iadd.24. A dual mode ultrasound imaging system having an array of acoustic transducer elements comprising:   B-mode imaging means to produce an electronically scanned acoustic image of an organism under examination, said B-mode image substantially representing an intensity of echoes returned from said organism along multiple B-mode scan lines;   Doppler-shifted-mode imaging means to produce an electronically scanned Doppler-shifted-mode image of said organism, said Doppler-shifted-mode image representing estimates of one of average velocity, variance, and power of moving scatters derived from Doppler-shifted echoes from said moving scatters in said organism from multiple sample volumes acquired along a direction of multiple independently propagated Doppler-shifted scan lines; and   a color display monitor displaying the B-mode image as a two dimensional image with echo intensities as encoded using a first mapping function and simultaneously displaying the Doppler-shifted image as a two dimensional image using a second and distinct mapping of red, green and blue components that is spatially coordinated with said B-mode image,   wherein the multiple lines of Doppler-shifted information are acquired in interleaved fashion in the Doppler-shifted-mode. .Iaddend.