Three-dimensional ultrasound tomography method and system based on spiral scanning

A three-dimensional ultrasound tomography system based on spiral scanning, comprising:

• a raw data collection module, used to:
• number array elements in a ring-shaped probe or a partial ring-shaped probe from 1 to N in a clockwise direction or a counterclockwise direction, where N is a total number of array elements in the probe, wherein the N array elements are uniformly distributed on the probe;
• under a premise that the probe maintains a uniform linear motion, an emission array element is switched according to a preset emission rule, and assuming that a motion-emission cycle contains L emission events, and each emission event corresponds to an equivalent emission array element, then the emission event numbered as 1 starts to emit an ultrasonic signal until the emission event numbered as L, and changes in trajectory with time of a position of the equivalent emission array element corresponding to each emission event in a three-dimensional space show a complete spiral or a partial spiral, so as to complete the motion-emission cycle;
• in this way, the emission array element is continuously updated to complete a plurality of motion-emission cycles;
• wherein for any emission event, while emitting the ultrasonic signal, each array element in the probe receives and collects the ultrasonic signal to obtain raw echo data;
• a data pre-processing module, used to:
• filter the raw echo data to obtain a filtered signal;
• a three-dimensional space coordinate calculation module of the emission array element, used to:
• calculate three-dimensional space coordinates of the equivalent emission array element of each emission event in each motion-emission cycle;
• a three-dimensional space coordinate calculation module of an imaging focus point, used to:
• perform voxelization on a three-dimensional imaging area and obtain three-dimensional space coordinates of each imaging focus point;
• and
• an image reconstruction module, used to:
• use the three-dimensional space coordinates of the equivalent emission array element of each emission event and the three-dimensional space coordinates of each of the imaging focus point, wherein in the three-dimensional imaging area, based on a principle of synthetic aperture focusing technique, each voxel in the three-dimensional imaging area serves as the imaging focus point for focusing point by point, so as to obtain an echo intensity distribution of each of the imaging focus point;
• based on the echo intensity distributions of the imaging focus points, the echo intensity distribution of the overall three-dimensional imaging area may be obtained;
• and filtering, envelope detection, logarithmic compression, and gray-scale mapping are performed on the echo intensity distribution of the overall three-dimensional imaging area to reconstruct a three-dimensional ultrasound tomography image,
• wherein using the three-dimensional space coordinates of the equivalent emission array element of each emission event and the three-dimensional space coordinates of each of the imaging focus point includes:
• it is assumed that a total number of emission events is W, and the emission events are numbered from 1 to W, for a certain imaging focus point P in the three-dimensional imaging area, based on the principle of synthetic aperture focusing technique, obtaining the three-dimensional space coordinates of the equivalent emission array element of each emission event, according to the three-dimensional space coordinates of the equivalent emission array element of a group of W emission events, the echo intensity distribution of the imaging focus point P is calculated, and the echo intensity distribution satisfies:
• I
• P
• =
• ∑
• i
• =
• 1
• W
• ∑
• j
• ⁢
• ε
• ⁢
• Ω
• i
• s
• i
• ,
• j
• (
• t
• -
• τ
• i
• ,
• j
• )
• where i corresponds to an equivalent emission array element of an i-th emission event in the group of W emission events, Ωi is a set composed of sub-aperture receiving array elements corresponding to the i-th emission event, and j represents an array element numbered as j in Ωi;
• and
• τ
• i
• ,
• j
• =
• 1
• c
• ⁢
• (
• d
• i
• ,
• T
• ⁢
• X
• +
• d
• j
• ,
• RX
• )
• d
• i
• ,
• T
• ⁢
• X
• =
• (
• x
• i
• -
• x
• P
• )
• 2
• +
• (
• y
• i
• -
• y
• P
• )
• 2
• +
• (
• z
• i
• -
• z
• P
• )
• 2
• d
• j
• ,
• RX
• =
• (
• x
• j
• -
• x
• P
• )
• 2
• +
• (
• y
• j
• -
• y
• P
• )
• 2
• +
• (
• z
• j
• -
• z
• P
• )
• 2
• where (xi, yi, zi) are three-dimensional space coordinates of the equivalent emission array element of the i-th emission event (xj, yj, zj) are three-dimensional space coordinates of a receiving array element when the array element numbered as j in the sub-aperture receiving array element set corresponding to the i-th emission event serves as the receiving array element (xp, yp, zp) are three-dimensional space coordinates of the imaging point P;
• di,TX is a spatial distance between the equivalent emission array element of the i-th emission event and the imaging point P, and dj,RX is a spatial distance between the receiving array element and the imaging point P when the array element numbered as j in the sub-aperture receiving array element set corresponding to the i-th emission event serves as the receiving array element c is a pre-selected sound speed value, preferably, c=1540 m/s;
• τi,j is a delay time of a sound wave starting from the equivalent emission element of the i-th emission event, passing through the imaging point P, and then reaching the array element numbered as j in the sub-aperture receiving array element set corresponding to the i-th emission event from the imaging point P when the element serves as the receiving array element si,j(t−τi,j)) represents a delay alignment echo signal received by the array element numbered as j in the sub-aperture receiving array element set corresponding to the i-th emission event when the element serves as the receiving array element.