Photoacoustic image reconstruction method for suppressing artifacts

Patent metadata

Field	Value
Publication number	US-11763500-B2
Application number	US-201917277355-A
Country	US
Kind code	B2
Filing date	Sep 17, 2019
Priority date	Oct 25, 2018
Publication date	Sep 19, 2023
Grant date	Sep 19, 2023

Abstract

The present disclosure provides a photoacoustic image reconstruction method for suppressing artifacts, including: acquiring relevant parameters of the system; selecting a suitable pixel size and dividing the imaging area into multiple pixels; traversing each pixel, calculating multiple delay and summations according to the time sequence, and restoring the signal waveform; calculating the signal envelope of the signal recovered from each pixel, performing signal suppression, suppressing artifacts in the signal, and retaining real signal; the real signal value in the suppressed signal is taken as the gray value of the pixel in the image, and is saved in the picture to complete the reconstruction of the image.

First claim

What is claimed is:

1. A method for suppressing artifacts in a photoacoustic image, comprising:
providing physical properties of a photoacoustic sensor and collecting photoacoustic signals s n tr (t), n=1, 2, 3, . . . , N from an imaging target area using the photoacoustic sensor;
selecting a pixel size for the imaging target area and dividing the imaging target area into multiple pixels;
calculating multiple delays and summations for each of said multiple pixels according to a time sequence, restoring a waveform of the multiple pixels, and calculating a signal envelope of the multiple pixels;
performing signal suppression on the signal envelope recovered from each of said multiple pixels to suppress artifact signals, thereby recovering a real signal value for each of said multiple pixels; and
using the real signal value as a grayscale value for each of the multiple pixels in the photoacoustic image, thereby reconstructing the photoacoustic image.

2. The method according to claim 1 , wherein physical properties of the photoacoustic sensor include a sampling frequency (f s ) of the photoacoustic sensor, a quantity (N) of sensor units of the photoacoustic sensor, and physical locations of the sensor units (r n tr , n=1, 2, 3, . . . , N).

3. The method according to claim 1 , wherein the selected pixel size is Δr, the imaging target area is divided into M pixel blocks according to the selected pixel size, and physical locations of the multiple pixels are defined as r m p , m=1, 2, 3, . . . , M.

4. The method according to claim 1 , wherein restoring the waveform of the multiple pixels comprises, for the m-th pixel, first calculating a distance between the m-th pixel and each of the sensor units, the distance being defined as d(m,n)=|r m p −r n tr |, n=1, 2, 3, . . . , N, then calculating a time delay of sound from the m-th pixel to each of the sensor units, the time delay being defined as

τ
⁡

(

m
,
n

)

=



r
m
p

-

r
n
tr



c
0

,

n=1, 2, 3, . . . , N, where c 0 is the speed of sound, thereafter using the calculated time delay to find a corresponding signal in the sensor, and restoring a beamforming signal of the m-th pixel using

s
m
p

⁡

(
t
)

=

∑

n
=
1

N

⁢

⁢

s
n
tr

⁡

(

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+

τ
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(

m
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.

5. The method according to claim 1 , wherein performing the signal suppression comprises locating a maximum value in the signal envelope Env m max =max(Env m (t)), selecting a suppression coefficient k to control signal suppression intensity, and calculating a suppressed signal using

Env
m
sup

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m

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)

·

(

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m

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Env
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max

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k

.

6. The method according to claim 5 , wherein the real signal value is the suppressed signal at time zero Env m sup (0).

7. The method according to claim 1 , further comprising, before collecting the photoacoustic signals, irradiating a laser light onto the imaging target area.

8. The method according to claim 4 , wherein calculating the signal envelope of the multiple pixels comprises, after the beamforming signal is stored, extracting the signal envelope from the beamforming signal using a Hilbert transform Env m (t)=|H[s m p (t)]|.

9. The method of claim 5 , wherein calculating the suppressed signal comprises calculating the suppressed signal for each of the multiple pixels at time zero, Env m sup (0), m=1, 2, 3, . . . , M, thereby completing image reconstruction.

Assignees

• Nanjing University Of Technology

Inventors

• Yuan Jie
• Ma Xiang
• Zhu Yunhao
• Guo Chengwen

Classifications

• G06T12/20

  Inverse problem, i.e. transformations from projection space into object space · CPC title

• G06T12/10

  Image preprocessing, e.g. calibration, positioning of sources or scatter correction · CPC title

• A61B5/0095 Primary

  by applying light and detecting acoustic waves, i.e. photoacoustic measurements · CPC title

• G06T11/00 Primary

  Two-dimensional [2D] image generation · CPC title

• G06T15/005

  General purpose rendering architectures · CPC title