Large depth-of-field photoacoustic-sonic dual-mode imaging method based on circular ultrasonic transducer array
An ultrasonic transducer, dual-mode imaging technology, applied in sensors, medical science, diagnosis, etc., can solve problems such as increasing cost, limiting the imaging effect of photoacoustic microscopy, and shallow imaging depth, and avoiding errors.
Active Publication Date: 2019-11-29
NANJING UNIV
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Problems solved by technology
[0003] However, the shallow imaging depth of field and the uncertainty of the sound velocity in the medium limit the imaging effect of photoacoustic microscopy
First of all, the traditional photoacoustic microscope generally uses a fixed-focus point-focusing transducer to detect photoacoustic signals, which can only obtain high-resolution images within the focal plane, while the image resolution outside the focal plane range drops sharply, so its imaging The depth of field is very shallow and is generally proportional to the length of the focal point of the ultrasound transducer
Second, the precise reconstruction of photoacoustic images depends on obtaining accurate medium sound velocity values. Traditional methods usually ignore the inhomogeneity of tissue sound velocity, but presuppose a unified sound velocity value based on prior knowledge, or use additional methods to obtain The prior information of the sound velocity not only increases the cost, but also cannot avoid the inaccuracy of the sound velocity value due to environmental factors and sample differences, resulting in image shift and image quality degradation
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[0042] The present invention will be further described below in conjunction with the accompanying drawings.
[0043] Such as figure 1 Shown is a large depth of field photoacoustic-acoustic dual-mode imaging method based on a circular ultrasonic transducer array, taking the imaging of hair strands in a multi-layer phantom with different sound velocities as an example, including the following steps:
[0044] Step 1: Mix agar, water and n-propanol in different proportions to make phantoms with different sound velocities in the upper and lower layers, and hair strands are distributed in the phantoms as samples. The sample is irradiated with a pulsed laser with a pulse width of about 10 ns (experimental system such as figure 1 shown).
[0045] Step 2: After the sample is irradiated by the pulsed laser, the acoustic signal is radiated to the surrounding due to the photoacoustic effect, and the radiated acoustic signal is received by the annular ultrasonic transducer array. A circ...
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The invention discloses a large depth of field photoacoustic- acoustic velocity dual mode imaging method based on annular ultrasonic transducer array. At first, the ultrasonic signal will be produced by using pulsed laser to irradiate samples. The acoustic velocity distribution information will be obtained according to the time delay of the signal reaching the annular ultrasonic transducer array, and then the acoustic velocity distribution image will be obtained. The sound velocity distribution information can also help to correct the acoustic velocity error when reconstructing the photoacoustic image to improve the imaging quality of photoacoustic images. Secondly, the photoacoustic image can maintain high lateral resolution over a long range of depths to obtain large depth of field high quality photoacoustic image through using dynamic focusing performance of ring ultrasonic transducer array. The dual mode imaging method can obtain the velocity distribution information and does not need to adopt additional means. The dual mode imaging method avoids the sound speed deviation caused by environmental factors and sample diversity. And the large depth of field, high quality photoacoustic image and a sound velocity distribution image are obtained at the same time, and the method has usability and practicability.
Description
technical field [0001] The invention relates to a method for realizing photoacoustic-sonic dual-mode imaging with a large depth of field by using an annular ultrasonic transducer array, specifically a method for realizing photoacoustic signal detection by using the correlation of photoacoustic signals detected by each array element of an annular ultrasonic transducer array. The sound velocity distribution of the medium is obtained, so as to obtain the ultrasonic sound velocity image of the medium; at the same time, the photoacoustic image of high quality and large depth of field is obtained through the dynamic focusing of the annular ultrasonic transducer array and the measured sound velocity of the medium. Background technique [0002] As a non-invasive biomedical imaging technique, photoacoustic microscopy has developed rapidly in recent years. Photoacoustic microscopy not only has the advantages of high resolution of deep tissue by acoustic methods, but also has the advan...
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IPC IPC(8): A61B5/00
CPCA61B5/0095A61B5/72
Inventor陶超丁秋宁刘晓峻
OwnerNANJING UNIV