# US 2017/0285151 A1 · Two dimension and three dimension imaging with coded pulses based on speed changes of sound/ultrasound

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- Number: US 2017/0285151 A1
- Document ID: US20170285151A1
- Status: Published application
- Kind: A1
- Application number: 15/613,308
- Filed: 2017-06-05
- Published: 2017-10-05
- Earliest claimed: 2014-11-04
- Assignees: Hai Huang; Tony Huang
- Inventors: Hai Huang; Tony Huang
- Web page: https://patentgrep.com/patent/US20170285151A1

## CPC

- G01S 7/523: Details of pulse systems {(short-range imaging G01S7/52017; methods or devices for transmitting, conducting or directing sound G10K11/18)}
- G01S 15/02: using reflection of acoustic waves (G01S15/66 takes precedence)
- G01S 15/58: Velocity or trajectory determination systems; Sense-of-movement determination systems {(velocity measurement in imaging systems G01S15/8979)}
- G01S 15/8986: {with measures taken for suppressing velocity ambiguities, i.e. anti-aliasing}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

During transmission, a speed of sound pulses gradually reduces due to acoustic impedance. Regulating a length or a density or a sound speed of the sound pulses affects their average speed in the transmitting medium, sound intensity and detecting depth. Time of flight (TOF) and TOF shift can be used to calculate the depth and moving speed of detecting objects. Calculating a speed of moving objects by simultaneously detecting TOF shift at same site from two separated piezoelectric (PZT) elements improves the testing results with accuracy, simplification and reproducibility. Coding sound pulses to obtained the TOF and the TOF shift will simultaneously calculate the depth and the moving speed of sampling points, which can be used to construct 2D and 3D images for these motionless and/or moving sampling points. Coded sound pulses also improves the quality of the imaging.

## Claims

### Claim 1

A method for calculating a detecting depth as speed reduction of sound pulses during a transmission, the method comprising:
calculating a speed reducing coefficient of the sound pulses in a transmitting medium, wherein the speed reducing coefficient of the sound pulses is directly proportional to the density of the transmitting medium and the traveling time (t) of the sound pulses and its constant value (k), and inversely proportional to a density and a thickness of the PZT elements, which comprising:
Speed


reducing


coefficient
=
k
×
medium


density
×
t
PZT


density
×
PZT


thickness
obtaining an average speed (Vavg) of the sound pulses in the transmitting medium, which comprising:
V
avg
=
V
m
×
(
1
-
k
×
medium


density
×
t
PZT


density
×
PZT


thickness
)
;
and
determining a detecting depth, wherein the detecting depth is a half multiplication value of the average speed and a traveling time of the sound pulses in the transmitting medium.

### Claim 2 (depends on 1)

A method of claim 1, further comprising regulating an intensity of the sound pulses to control their traveling distance. The sound intensity is a multiplication value of the length of the sound pulses and the density of the sound pulses and the speed of the sound pulses, which comprising:
Sound intensity(kg/MS)=sound length(M)×sound density(Kg/M3)×sound speed(M/S)
M=meter; Kg=kilogram; S=second.

### Claim 3 (depends on 2)

The method of claim 2, further comprising optimizing depth related imaging by compounding sound pulses with different length to focus at their appropriate detecting depth.

### Claim 4 (depends on 3)

The method of claim 3, further comprising increasing detecting depth for high frequency sound pulses by increasing the density and the speed of the sound pulses wherein the thickness of the PZT elements decides the length of the sound pulses as well as limits the highest frequency a sound system can reach.

### Claim 5 (depends on 2)

The method of claim 2, further comprising improving axial resolution by decreasing the length of the sound pulses.

### Claim 6

A method of using time of flight (TOF) shift of the sound pulses to calculate a velocity of moving objects in a continuous, a pulsed and a color ultrasound, the method comprising:
setting a baseline wherein the baseline in the pulsed ultrasound is calculated TOF between a transducer and a gate and in the continuous ultrasound is a time of an emitted period, and a TOF shift equals to zero at the baseline;
for pulsed ultrasound, detecting TOF is a time from sending ultrasound pulses to receiving the reflected ultrasound pulses, and for continuous ultrasound, a reflected period is a time between two consecutive reflected sound pulses from a sampling point;
calculating the TOF shift wherein the TOF shift for the pulsed ultrasound is a time difference between the calculated TOF and the detected TOF, and TOF shift for the continuous ultrasound is a time difference between is the emitted period and the reflected period; and
calculating the velocity of the moving objects (Vobjects) based on an equation of TOF shift including an angle θ of the sound beam made with the moving objects, an average speed (Vavg) of the sound pulses in the transmitting medium, the transducer frequency (f), wherein the TOF shift is the TOF shift for the continuous, the pulsed and the color ultrasound, the equation of the TOF shift is:
TOF


shift
=
2
×
V
objects
×
f
×
cos

(
θ
)
V
avg

### Claim 7 (depends on 6)

The method of claim 6, further comprising calculating a speed of the moving objects by simultaneously detecting TOF shift at same site from two separated PZT elements, wherein the speed of the moving objects can be calculated based on the values of the TOF shifts, the transducer frequency, the angle μ between two sound beams from the PZT elements and the average speed of the sound pulses in the transmitting medium as the following equation:
V
objects
=
V
avg
×
(
TOF


shift


A
)
2
-
2
×
TOF


shift


A
×
TOF


shift


B
×
cos

(
μ
)
+
(
TOF


shift


B
)
2
2
×
f
×
sin

(
μ
)

### Claim 8 (depends on 6)

The method of claim 6, further comprising changing the intensity and the angle of the sending sound pulses to regulate the speed of the reflected sound pulses wherein the changes of the speed of the reflected sound pulses alter the TOF and the TOF shift of the sound pulses.

### Claim 9 (depends on 6)

The method of claim 6, further comprising a method of calculating the velocity of the moving objects for the continuous ultrasound comprising:
setting a time of an emitted period as the baseline wherein the time of the emitted period is the time between previously and following emitted pulses;
obtaining a time of a reflected period for each sampling points below the PZT elements wherein the time of the reflected period is the time between previously and following reflected sound pulses;
calculating a TOF shift for these sampling points wherein the TOF shift is a time difference between the time of the emitting period and the time of the reflected period, and the TOF shift is variable for the sampling points with the moving objects; and
using the TOF shift to calculate the velocity of the moving objects based on the equation of TOF shift.

### Claim 10 (depends on 6)

The method of claim 6 further comprising a method of calculating the velocity of the moving objects for the pulsed and the color ultrasound comprising:
setting a time of a calculated TOF as the baseline wherein the calculated TOF is the time that sound system calculates according to a distance between a transducer and a gate and the average speed of the sound pulses in the transmitting medium;
obtaining the detected TOF wherein the detected TOF is the time that sound system interprets from sound pulses traveling between the transducer and the gate, before an aliasing the detected TOF is an actual TOF, and the actual TOF is a truly traveling time of the sound pulses;
calculating a TOF shift wherein the TOF shift is a time difference between the value of the calculated TOF and the value of the detected TOF; and
using the TOF shift to calculate the velocity of the moving objects based on the equation of the TOF shift.

### Claim 11 (depends on 10)

The method of claim 10 further comprising a method to correctly calculate the velocity of the moving objects after the aliasing for the pulsed and the color ultrasound comprising:
identifying an aliasing TOF, wherein as the actual TOF excesses its aliasing limit, the detected TOF is misinterpreted by sound system to generate the aliasing TOF, the aliasing TOF shift is on opposite site of the baseline and disrupts continuity of a profile of the TOF shift, and a tip of a profile of the aliasing TOF shift is toward the baseline;
obtaining a corrected TOF shift by rectifying the aliasing TOF shift to correct registration of the reflected sound pulses after the actual TOF exceeds the aliasing limit, the tip of the profile of corrected TOF shift is away from the baseline, and the corrected TOF shift reconstructs the continuation of the profile of the TOF shift; and
using the corrected TOF shift to calculate the velocity of the moving objects based on an equation of corrected TOF shift:
Corrected


TOF


shift
=
2
×
V
objects
×
f
×
cos

(
θ
)
V
avg

### Claim 12 (depends on 11)

The method of claim 11, wherein for forward moving objects, the velocity of the moving objects is correctly calculated after the aliasing by:
identifying the aliasing for the forward moving objects wherein the aliasing limit for the actual TOF is less than a value of half calculated TOF; after the actual TOF excesses the aliasing limit, the sound system misinterprets the detected TOF by adding a value of one calculated TOF to a value of the actual TOF to form an aliasing TOF, the value of the aliasing TOF is greater than the value of the baseline and its TOF shift is located on an opposite site of the baseline, and the aliasing TOF shift disrupts the continuation of the profile of the TOF shift, and the tip of the profile of the aliasing TOF shift is toward the baseline;
obtaining the corrected TOF shift by subtracting a value of the aliasing TOF shift from a value of the calculated TOF to reestablish the continuation of the profile of the TOF shift; and
using the corrected TOF shift to calculate the velocity of the forward moving objects based on the equation of corrected TOF shift.

### Claim 13 (depends on 11)

The method of claim 11, wherein for reversely moving objects, the velocity of the moving objects is correctly calculated after the aliasing by:
identifying the aliasing for the reversely moving objects wherein the aliasing limit for the actual TOF is greater than the value of one and half calculated TOF; after the actual TOF excesses the aliasing limit, the sound system misinterprets the detected TOF by subtracting a value of one calculated TOF from a value of the actual TOF to form an aliasing TOF; the value of the aliasing TOF is smaller than the value of the baseline and the aliasing TOF shift is located on the opposite site of the baseline, and the aliasing TOF shift disrupts the continuation of the profile of the TOF shift, and the tip of the profile of the aliasing TOF shift is toward the baseline;
obtaining the corrected TOF shift by subtracting a value of the calculated TOF shift from a value of the aliasing TOF shift to reestablish the continuation of the profile of the TOF shift; and
using the corrected TOF shift to calculate the velocity of the reversely moving objects based on the equation of corrected TOF shift.

### Claim 14 (depends on 10)

The method of claim 10 further comprising a method of avoiding the aliasing by modifying the computer program in the sound system to prevent adding or subtracting a value of a calculated TOF from the detected TOF after the actual TOF excesses its aliasing limit.

### Claim 15 (depends on 11)

The method of claim 11, further comprising a method of differentiating a color of the aliasing from a color of turbulent flows and rectifying the color of the aliasing for the color ultrasound comprising:
identifying the aliasing TOF shift for the color of the aliasing wherein from one color to a edge of another color, the value of their TOF shift is gradually increased until close to the value of half calculated TOF, and the profile of the aliasing TOF shift is more close to the value of half calculated TOF, and the tip of the profile of the aliasing TOF shift is toward the baseline; a color of no-aliasing represents a flow before its actual TOF excesses the aliasing limit, the profile of the no-aliasing TOF shift is more closer to the baseline, and the tip of the no-aliasing TOF shift is away from the baseline;
identifying the TOF shift for the color of turbulent flows wherein from one color to a edge of another color, the value of their TOF shift is gradually decreased until close to zero, the tip of the profile of the TOF shift for the color of turbulent flows is away from the baseline; and
rectifying the color of the aliasing wherein the aliasing TOF shift is corrected according to the direction of the no-aliasing flow, and the color of the aliasing is corrected based on the value of the corrected TOF shift.

### Claim 16

A method of calculation of the detecting depth and the moving velocity of sampling points with coded sound pulses comprising:
a transducer contains one pair or more of emitting PZT elements and receiving PZT elements, assigning different numbers of the sound pulses within each pulse duration to form different pulse characters, a resting period is a time between each adjacent pulse duration;
the emitting PZT elements emit specifically coded pulse characters, which endow information of an emitting time for each pulse character, and the resting period for the emitted sound pulses keeps identical;
the receiving PZT elements receive reflected sound pulses, and decode received pulse characters to compare with the emitted codes of the pulse characters, TOF is obtained from a time between the emitted pulse character and the same reflected pulse character, and TOF shift is obtained from a time difference between the emitted resting period and the correspondingly received resting period;
identifying motionless sampling points from the reflected sound pulses with identical value of the TOF and zero value of the TOF shift, therein the depth of the motionless sampling points is calculated from the TOF; and
identifying moving sampling points from the reflected sound pulses with variable values of the TOF and the TOF shift, therein the velocity of the moving sampling points is calculated with the equation of the TOF shift, the depth of the moving sampling points is a half multiplication value of the sum of the TOF and the TOF shift with the average velocity of sound in the transmitting medium, for forward moving sampling points, the TOF shift is positive value, and for reversely moving sampling points, the TOF shift is negative value, the equation of calculating the depth of the moving sampling points comprising:
depth of moving sampling points=Vavg×(TOF+TOF shift)/2

### Claim 17 (depends on 16)

The method of claim 16 further comprising improving noise and artifacts with coded sound pulses wherein by comparing the received codes of the pulse characters with the emitted codes of the pulse characters, the reflections of the coded sound pulses from the sampling points that have the identical received codes of the pulse characters with the emitted codes of the pulse characters will be registered to an area that belongs to the PZT element that emits the codes of the pulse characters.

### Claim 18 (depends on 16)

A method of claim 16, further comprising applications in construction of three dimensional images for motionless and/or moving sampling points with the coded sound pulses comprising:
obtaining a dataset (x, y, v) of two dimension (2D) images with the coded sound pulses, the values of x and y represent a value of two axes of the sampling points in 2D images, a value of v represents a velocity of the sampling points, which comes from TOF shift;
obtaining a dataset (x, y, z, v) of three orthogonal axes from plurality of succession of 2D dataset, a value of z represents a position of the objects in a volumetric image array; and
constructing 3D images for motionless and/or moving sampling points with related computer programs by using the obtained data of three orthogonal axes (x, y, z), and the value of v can be used to represent the status of movement and velocity of objects with different colors.

### Claim 19 (depends on 16)

A method of claim 16, further comprising improving 2D and 3D imaging quality by increasing temporal resolution with coded sound pulses.