CN2915036Y - Photoacoustic Imaging and Tomography Device Based on Acoustic Lens - Google Patents

Abstract

The utility model relates to a photoacoustic imaging and tomographic imaging device based on an acoustic lens. Circuit, capture card, computer. Among them, the transparent flexible rubber layer, optical fiber, acoustic lens and the two-dimensional area array photoacoustic detector are relatively installed in a cylindrical aluminum cavity; the optical fiber is connected to the laser through a connector to form a light source; the two-dimensional area array photoacoustic detector, The detector output signal circuit, the delay-signal conversion circuit, the acquisition card and the computer are electrically connected in sequence. The utility model uses the acoustic lens to directly realize photoacoustic imaging on biological tissues, realizes tomographic imaging on samples to be tested with the same or similar acoustic impedance but different optical parameters, and performs real-time imaging; the utility model has high sensitivity and does not cause radioactive damage to organisms.

Description

Photoacoustic imaging and laminated imaging device based on acoustic lens

Technical field

This utility model relates to the photoacoustic tomography technology, specifically is based on the photoacoustic imaging and the laminated imaging device of acoustic lens.

Background technology

Photoacoustic tomography is to detect to bury in the scattering medium interior lights to absorb a kind of effective potential medical imaging technology that distributes, and it combines the advantages such as high-penetrability of optical strong contrast and ultra sonic imaging, has become the focus of present research.In photoacoustic imaging research, use short-pulse laser (nanosecond) to be radiated in the biological tissue, biological tissue be because thermal-elastic expansion take place in the faint rising of absorbing light energy amount temperature, produces ultrasonicly, and ultrasonic signal is proportional to the light absorption of biological tissue.So photoacoustic signal has carried the information of organizing optical absorption characteristics, and physiological feature, growth or the metabolism state of the characteristic of the light absorption of biological tissue and tissue, pathological changes characteristic etc. are relevant closely, can be used for judging and screen its inner situation.For example, the luminous absorptance normal structure height of the normal growth situation of biological tissue, early stage cancerous issue.Tissue much smaller than decay and the scattering of tissue to light, uses ultrasonic probe to detect the image that ultrasonic energy reconstructs the distribution of the light absorption in the tissue to Ultrasonic attenuation and scattering.Traditional supersonic sounding or X image technology mainly rely on the difference of the absorption of local acoustical impedance in the biological tissue or X ray to come imaging, but these differences are little in the pathological tissues in early days.And the metabolism of pathological tissues and normal structure on every side differ greatly; For example, blood capillary around the early stage cancerous issue is just much abundant than normal structure, and oxygen content height, this has than big-difference with regard to the optical characteristics that causes it and normal surrounding tissue, utilizes photoacoustic signal just can come imaging according to the metabolic function difference of biological pathological tissues and normal structure.On the operation principle of imaging device, the general at present algorithm for reconstructing that uses is rebuild original optoacoustic pattern, but because algorithm itself requires to scan or data are average, consuming time longer, the monitoring tissue that this can not be real-time changes.So real-time acquisition biological tissue tomographic map is the key issue that this technological direction is used.

The utility model content

The purpose of this utility model is the defective that exists at prior art, provide a kind of to biological tissue's high-resolution, Noninvasive and operation eaily based on the photoacoustic imaging and the laminated imaging device of acoustic lens.

This utility model with acoustic lens since the acoustic pressure distribution direct imaging that optoacoustic effect produces on image planes, on image planes, survey then with a two-dimensional array optoacoustic detector, the photoacoustic signal that is obtained is carried out two-dimensional imaging, can obtain the plane picture of biological tissue to be measured in real time.In like manner,, therefore select the different photoacoustic signal of delay time to carry out imaging, can obtain the image of the biological tissue of different aspects apace because the photoacoustic signal that biological tissue produced of different depth is transferred to the asynchronism(-nization) of optoacoustic detector.

This utility model utilizes acoustic lens that biological tissue's photoacoustic tomography device is made of transparent flexible rubber layer, optical fiber, acoustic lens, two-dimensional array optoacoustic detector, detector output signal circuit, time-delay-signaling conversion circuit, capture card, computer.Wherein transparent flexible rubber layer, optical fiber, acoustic lens is relative with the two-dimensional array optoacoustic detector is installed in the column type al-made chamber; Optical fiber connects to form light source by an adapter and laser instrument; Two-dimensional array optoacoustic detector, detector output signal circuit, time-delay-signaling conversion circuit, capture card, computer are electrically connected successively.

Wherein the two-dimensional array optoacoustic detector has the ability and the spatial resolving power of detecting ultrasonic signal, and the detector output signal circuit is characterized in that and can visit first signal by interim storage surface array detector, amplifies, exports ultrasonic signal then successively.

The fixing a certain time-delay of described time-delay---signaling conversion circuit is converted to corresponding DC voltage to the ultrasonic signal amplitude, and this constant time lag can be regulated.

Data processing software is housed in the computer, is used for organism or tissue image and rebuilds and handle.For example use the automated image acquisition process software of the Visual C++6.0 platform development of Microsoft company.

Described acoustic lens is made by aluminium.The position of this acoustic lens is adjustable, adjustable extent meeting geometric optical imagery character, promptly $\frac{1}{u}+\frac{1}{v}=\frac{1}{f}.$

The two-dimensional array optoacoustic detector is made by piezoelectric ceramics or Kynoar (PVDF).

The using method of this utility model device comprises the steps:

(1) be the pulsed laser irradiation biological tissue of 5～20 nanoseconds (ns) with pulsewidth, producing frequency in biological tissue is the ultrasonic of megahertz (MHz), i.e. photoacoustic signal;

(2) with acoustic lens laser induced biological tissue's acoustic pressure or the distribution of different aspects acoustic pressure are imaged on the image planes with imaging capability;

For example the photoacoustic signal of tumor is just strong than the photoacoustic signal around the tissue; The acoustic lens depth of focus is bigger, and the certain thickness object is had vertical imaging capability; Acoustic lens distributes the different aspects acoustic pressure of biological tissue and is imaged on the corresponding image planes;

(3) on a certain image planes, survey acoustic pressure and distribute, gather photoacoustic signal with the two-dimensional array optoacoustic detector;

(4) photoacoustic signal of being gathered is advanced image reconstruction, obtain the tissue image of a certain aspect clearly;

(5), repetitive operation step (3), (4), the light absorption image of acquisition biological tissue different aspects.

In the described step (1), the pulse laser optimal wavelength is 450nm～2000nm.

In the described step (3), select the signal of the different image planes of biological tissue by the time-delay of control acquired signal.

This operation principle based on biological tissue's photoacoustic tomography device of acoustic lens is: the pulsed laser irradiation that pulse laser sends is on sample, and sample produces photoacoustic signal; The photoacoustic signal that produces is transformed on the image planes by acoustic lens through couplant; Detector is surveyed the signal of image planes on image planes, time-delay---signaling conversion circuit is fixed same time-delay, and changes the DC voltage of this signal for correspondence; This DC voltage is sent into computer recording through capture card A/D conversion; Computer is converted to gray-scale map and is shown as picture automatically.

This utility model compared with prior art has following advantage and effect:

(1) this utility model device is to utilize photoacoustic signal to carry out two-dimensional imaging and tomography, and photoacoustic signal carries more information than traditional ultrasound wave, can realize the biological function imaging.This utility model device combines the ultrasonic advantage that has the strong contrast of strong penetration capacity and optical imagery in biological tissue, can not produce radiation injury to organism, compare with traditional medical imaging diagnosis device have Noninvasive, advantage such as not damaged and sensitivity height.

(2) this utility model device is to utilize TIME RESOLVED TECHNIQUE to realize tomography, can realize the imaging of super-resolution chromatography.

(3) this utility model device use acoustic lens because the acoustic pressure that optoacoustic effect excites distribution images on the image planes, has the advantage of realtime imaging to certain aspect of biological tissue; And the imaging depth of focus of acoustic lens is bigger, can utilize temporal time-delay to realize tomography.

(4) time-delay---the signaling conversion circuit in this utility model device, different image planes are selected in the time-delay of control signal collection effectively, reliably easily.

(5) this utility model can obtain identical and the close and tomographic map testing sample that optical parametric is different of acoustic impedance; This utility model adopts acoustic lens directly to biological tissue's tomography, need not the complex image algorithm for reconstructing, can realize the realtime imaging to biological tissue.

(6) this utility model can obtain the information of a certain dimension transverse of biological tissue, the imaging mode that obtains a certain axial section information with B ultrasonic etc. is different, this cross direction profiles with the many structures of biological tissue is consistent, for example in vivo vascularity, tumor shape or the like can provide abundanter information for medical diagnosis.

(7) data acquisition of the present utility model and image reconstruction be all fully by computer control, so the operation of device is comparatively convenient, and the automaticity height.

Description of drawings

Fig. 1 is the structured flowchart of this utility model device;

Among the figure: 1. column type aluminum exocoel 2. couplants 3. transparent flexible rubber layers 4. optical fiber 5. fiber fixed frames 6. adapters 7. laser instrument 8. acoustic lens 9. two-dimensional array optoacoustic detectors 10. detector output signal circuit 11. time-delay-signaling conversion circuits 12. capture cards 13. computers

Fig. 2 is the acoustic lens tomography principle schematic of this utility model device;

Wherein Fig. 2 a is the tomography schematic diagram of acoustic lens part; Fig. 2 b is optical equivalence figure.

The specific embodiment

Below in conjunction with embodiment and accompanying drawing this utility model is done further detailed narration, but embodiment of the present utility model is not limited thereto.

As seen from Figure 1, this utility model device mainly comprises transparent flexible rubber layer 3, optical fiber 4, acoustic lens 8, two-dimensional array optoacoustic detector 9, detector output signal circuit 10, time-delay-signaling conversion circuit 11, capture card 12, computer 13.Wherein transparent flexible rubber layer 3, optical fiber 4, acoustic lens 8 and two-dimensional array optoacoustic detector 9 relative being installed in the column type al-made chamber 1; Optical fiber 4 connects to form light source by an adapter 6 and laser instrument 7; The fiber fixed frame of being made by agar is fixed in the outer intracavity of aluminum column type.Two-dimensional array optoacoustic detector 9, detector output signal circuit 10, time-delay-signaling conversion circuit 11, capture card 12, computer 13 are electrically connected successively.Select for use each member to connect to form this device, wherein: the MOPO (Model:PRO2230) that laser instrument 7 selects for use Spectra-Physics to produce, can send the pulse laser that wavelength is 500nm-2000nm, it is the green laser of 532nm that present embodiment is selected wavelength for use, and its repetition period is 30HZ; Acoustic lens 8 is Design and Machining voluntarily; Two-dimensional array optoacoustic detector 9 selects for use 32*32 to visit first planar array detector; Detector output signal circuit 10 is selected homemade electronic switching circuit for use; Time-delay---signaling conversion circuit 11 is selected homemade peak-holding circuit for use; Capture card 12 is selected the PCL2818HG data collecting card (Model:Advantech) of Adc Inc. for use; Computer 13 is selected the Pentium3 microcomputer for use.

As Fig. 2 a, shown in the b, the acoustic lens imaging of this utility model device and tomography principle are as follows: the power of photoacoustic signal is proportional to the absorption coefficient of light of sample, and photoacoustic signal has all features (as interfering and diffraction) of fluctuation, according to Fourier's imaging theory, acoustic lens with spatial fourier transform character, can directly carry out two-dimensional imaging to photoacoustic signal, thing with the picture between corresponding one by one, shown in Fig. 2 a, its optical equivalence figure is shown in Fig. 2 b, by measuring the distribution of amplitudes of each point photoacoustic signal on the image planes, just can obtain two-dimentional photoacoustic image.According to the object-image conjugate principle, the needed time of corresponding picture point is identical on the photoacoustic signal arrival image planes that each point sends on the object plane, and the time of the photoacoustic signal that different object plane produced arrival image planes has nothing in common with each other, utilize TIME RESOLVED TECHNIQUE, gather the image planes photoacoustic signal by controlling different delay times, thereby obtain the photoacoustic image of different image faces.Its work process is as follows: the laser that laser instrument 7 sends imports four optical fiber through adapter 6, incide strong scattering solution from the laser of four optical fiber output and form equally distributed light field, the uniform distribution light field sees through transparent flexible rubber layer 3 and illuminates testing sample, and in sample, inspire photoacoustic signal, photoacoustic signal is imaged on the two-dimensional array optoacoustic detector 9 by acoustic lens imaging 8, two-dimensional array optoacoustic detector 9 converts photoacoustic signal to the signal of telecommunication, and by detector output signal circuit 10 amplification and signal processing, carry out signals collecting by capture card 12 then, and be input to computer 13 and store and image reconstruction, obtain the photoacoustic image of an aspect.Select different delay times by time-delay-signaling conversion circuit 11 then, obtain the photoacoustic image of different aspects.

Use strong scattering solutions simulate biological tissue environment, imaging function to the single aspect of acoustic lens is specifically implemented, four black tape point-like samples (being attached on the transparent lucite) bury in strong scattering solution, when transparent flexible rubber layer contact solution, and it is parallel relative with the aspect at sample place, regulate acoustic lens to the appropriate location, can be quickly and easily in the computer reconstructing photoacoustic image.

Use strong scattering solutions simulate biological tissue environment, acoustic lens tomography function is specifically implemented.Burying has two-layer black tape sample in strong scattering solution, one deck is the ring shape sample, and another layer is three black tape point-like samples, and they are attached to the poly (methyl methacrylate) plate front and rear surfaces respectively.Be similar to the concrete enforcement of above-mentioned acoustic lens simple layer surface imaging, promptly obtain the photoacoustic imaging figure of circle layer, only need to regulate control time-delay---signaling conversion circuit on this basis, the promptly convenient photoacoustic imaging figure that obtains 3 layers fast.

In biological tissue, acoustic lens tomography function is specifically implemented.Be stained with the black glue pattern of a ring shape and 3 shapes on two aspects of the Pork-pieces of a thick 5mm of being about respectively.Be similar to the concrete enforcement of above-mentioned acoustic lens tomography, promptly obtain the photoacoustic imaging figure of two aspects respectively.

Claims (3)

1. A photoacoustic imaging and tomographic imaging device based on an acoustic lens, characterized in that it consists of a transparent flexible rubber layer, an optical fiber, an acoustic lens, a two-dimensional area array photoacoustic detector, a detector output signal circuit, and a delay-signal It is composed of conversion circuit, acquisition card and computer; among them, transparent flexible rubber layer, optical fiber, acoustic lens and two-dimensional area array photoacoustic detector are installed in a cylindrical aluminum cavity; the optical fiber is connected with a laser through a connector to form a light source; The two-dimensional area array photoacoustic detector, the detector output signal circuit, the delay-signal conversion circuit, the acquisition card, and the computer are electrically connected in sequence. 2. The device according to claim 1, characterized in that the acoustic lens is made of aluminum, the position of the acoustic lens is adjustable, and the adjustable range satisfies the geometrical optical imaging properties, namely $\frac{1}{u}+\frac{1}{v}=\frac{1}{f}.$ 3. The device according to claim 1 or 2, characterized in that the two-dimensional area array photoacoustic detector is made of piezoelectric ceramics or polyvinylidene fluoride (PVDF).