WO2013047971A1

WO2013047971A1 - Photo-acoustic imaging device using a near infrared laser

Info

Publication number: WO2013047971A1
Application number: PCT/KR2012/003669
Authority: WO
Inventors: 송철규
Original assignee: 전북대학교산학협력단
Priority date: 2011-09-27
Filing date: 2012-05-10
Publication date: 2013-04-04

Abstract

The present invention relates to a photo-acoustic imaging device using a near infrared laser, including: a probe; a laser-emitting unit installed on the probe and emitting a laser to the tissues of living bodies; a transducer installed on the probe and sensing ultrasonic waves that spontaneously arise through thermal elastic expansion from the tissues of the living bodies to which the lasers are emitted; and a control unit generating the photo-acoustic images and oxygen saturation distribution of the tissues of the living bodies through the ultrasonic waves sensed by the transducer and mapping the generated photo-acoustic images of the tissues of the living bodies to the generated oxygen saturation distribution.

Description

【Specification】

[Name of invention]

Optoacoustic Imaging Device Using Near Infrared Laser

Technical Field

The present invention relates to an optoacoustic imaging apparatus, and more particularly, to an optoacoustic imaging apparatus using a near infrared laser.

Background Art

<2> In general, living tissues may progress to lesions for various reasons. At this time, as the lesion progresses, structural changes in the tissues and oxygen saturation in the tissues are changed. ^'

<3>

In this case, an ultrasound diagnostic method is generally used to check the state of living tissue. Specifically, the ultrasonic diagnostic method may determine the state of the living tissue by measuring the reflected sound waves by irradiating the ultrasonic tissue onto the living tissue. However, in the ultrasonic diagnostic method as described above, when ultrasonic waves are irradiated onto a living tissue, ultrasonic waves are partially absorbed from the tissue, and thus, reflected waves may not be properly generated. Therefore, in the case of using a general ultrasound diagnostic method, due to the above-described problems in the living tissues in which the vascular tissues are developed, as in the lesion tissues, the resolution is insufficient to find the exact shape of the lesion tissues. there is a problem.

<5>

On the other hand, it is possible to use a high-resolution X-ray diagnostic apparatus in order to overcome a low resolution image, such as the ultrasonic diagnostic method described above. But,

In the case of an X-ray diagnostic apparatus and the living tissue exposed to X-rays, there is a problem that some damage or deformation of the living tissue may occur.

<7>

Therefore, it is necessary to obtain accurate and high resolution biotissue images that are harmless to the human body for the accurate diagnosis or rapid treatment of diseases. To confirm, it is necessary to confirm the degree of acid saturation along with the biological tissue image. Oxygen saturation refers to the percentage of oxidized hemoglobin concentration out of the total hemoglobin concentration in the tissue.

[Detailed Description of the Invention] [Technical problem]

Embodiments of the present invention are to provide an optoacoustic imaging apparatus capable of functionally monitoring the state of a tissue by simultaneously measuring the oxygen saturation and the tissue structure, which is physiological information of the tissue.

<10>

<π> It is also intended to provide not only functional information but also anatomical information through co-registration with ultrasound images.

Technical Solution

According to an aspect of the present invention, an optoacoustic imaging apparatus using a near infrared laser includes a probe; A laser emitter installed in the probe and emitting a laser beam irradiated onto living tissue; A transducer installed at the probe and configured to sense ultrasonic waves generated by thermoelastic expansion in the tissue irradiated with the laser; And a controller configured to generate a photoacoustic image and an oxygen saturation distribution of the biological tissue through the ultrasonic waves sensed by the transducer, and to map the generated photoacoustic image and the oxygen saturation distribution of the biological tissue. .

<13>

The laser emitter of the optoacoustic imaging apparatus using a near infrared laser according to an embodiment of the present invention may use a Nd: Yag laser.

<15>

The transducer of the optoacoustic imaging apparatus using a near infrared laser according to an embodiment of the present invention may acquire a tomography image by a back projection method while rotating the living tissue.

<17>

An optoacoustic imaging apparatus using a near infrared laser according to an embodiment of the present invention is rotatably installed on the probe to detect a path of the laser emitted from the laser emitter and the ultrasonic wave incident on the transducer. It may further include a variable rotation drive unit.

<19>

The rotation driving unit of the optoacoustic imaging apparatus using a near infrared laser according to an embodiment of the present invention may include a mirror unit for changing a path of the laser and the ultrasonic wave, and a driver unit for rotating the mirror unit. Can be. The probe of the optoacoustic imaging apparatus using a near infrared laser according to an embodiment of the present invention is formed in the shape of a cylinder lamp, and is disposed on a path of the laser along the outer circumferential surface of the probe to allow the laser to pass therethrough. The plastic membrane portion to be formed may be installed.

<23>

The optoacoustic imaging apparatus using a near infrared laser according to an embodiment of the present invention may further include an amplifier installed between the transducer and the controller to amplify the ultrasonic wave detected by the transducer.

<25>

The photoacoustic image acquisition method according to an embodiment of the present invention includes a laser irradiation step of irradiating a laser onto a living tissue; An ultrasonic sensing step of sensing ultrasonic waves generated by thermoelastic expansion in the tissue irradiated by the laser through a transducer; An ultrasound image acquisition step of obtaining an ultrasound image of the living tissue through the ultrasound stream detected by the transducer; An optoacoustic image acquisition step of obtaining an optoacoustic image of the biological tissue by receiving and imaging the ultrasonic wave sensed by the transducer; And a mapping step of mapping the ultrasound image and the photoacoustic image to obtain anatomical information as well as functional information of a living tissue.

Advantageous Effects

The photoacoustic imaging apparatus using the near infrared laser according to the embodiments of the present invention, unlike the conventional method, can obtain sufficient image contrast for structural change of the biological tissue at the same time as measuring oxygen saturation of the biological tissue. Depending on the stage of the disease, a morphological diagnosis of muscle disease and joint disease, which requires detailed analysis, may be possible.

<28>

In other words, the photoacoustic signal is imaged by receiving ultrasonic waves generated by thermal expansion caused by absorbed light energy after irradiating the laser, and using this to oxidize / reduce hemoglobin in the blood. It can also be useful for early cancer diagnosis.

<3>

In addition, because of the high contrast of photoacoustic images in various tumors and cancer tissues, the use of these characteristics can provide both anatomical and anatomical information at the same time. . <32>

In addition, since the photoacoustic imaging device utilizes non-ionized electromagnetic radiation, it is harmless to the human body, and because it relies on near-infrared absorption, it is sensitive to abnormal biological tissues and thus can be used for early diagnosis of cancer.

<34>

In addition, the photoacoustic imaging apparatus may combine the ultrasonic imaging method with the photoacoustic imaging method and may correct the diagnostic image according to the ultrasonic nonuniformity. In addition, the photoacoustic imaging device is equally applicable to the diagnostic field applying the current ultrasonic diagnostic method, and when combined with existing ultrasonic equipment or optical diagnostic equipment such as OCT, it can be utilized as a more efficient type of diagnostic apparatus. In addition, there is a technical advantage that it is efficient to accurately find the tissue structure surface of the border portion of the tumor.

[Brief Description of Drawings]

1 is a conceptual diagram illustrating an optoacoustic imaging apparatus according to an embodiment of the present invention.

2 is a conceptual diagram illustrating an optoacoustic imaging apparatus according to another embodiment of the present invention.

FIG. 3 shows the change in oxidized hemoglobin absorption spectrum with wavelength change.

4 to 5 illustrate photoacoustic signals that change depending on the presence or absence of a light absorbing material.

6 to 8 show phantom experiments for comparing the accuracy of the size and spacing of the light absorbing material.

9 shows the device configuration for the blood and fan team experiment.

10 to 14 illustrate photoacoustic image changes over time obtained through the experiment according to FIG. 9.

15 to 16 show the size and arrangement of the phantom model using dyes and the experimental results.

17 to 20 show experimental results of hemoglobin concentration based on wavelengths obtained based on experimental results according to FIGS. 15 and 16.

FIG. 21 shows the amplitude change of the photoacoustic signal when the ratio of red purple dye and cyan dye is changed.

FIG. 22 shows a fan team with two red leads embedded in gelatin.

FIG. 23 illustrates an optoacoustic image of the phantom illustrated in FIG. 22. FIG. 24 illustrates an optoacoustic image in which the fan team shown in FIG. 23 is enlarged.

FIG. 25 illustrates an image (b) in which an ultrasound image (a) and a photoacoustic image are mapped.

FIG. 26 illustrates an ultrasound image (a) in which the image shown in FIG. 25 is magnified and an image (b) in which an optoacoustic image is mapped.

<51>

[Form for implementation of invention]

Hereinafter, a specific embodiment of the optoacoustic image device according to the present invention will be described in detail with reference to the accompanying drawings.

<53>

On the other hand, the optoacoustic imaging apparatus according to an embodiment of the present invention is an optoacoustic imaging technique that combines a high resolution of an ultrasound image and a high contrast ratio of an optoacoustic signal. It is characterized by a technique that can measure saturation and structural change at the same time, and aims to increase diagnostic accuracy through this.

<55>

On the other hand, photoacoustic imaging used in the present invention has been developed based on the photoacoustic effect as a hybrid biomedical imaging modality. In optoacoustic images, non-ionized laser fields can be delivered to living tissue (RF pulses are used, also called thermoacoustic images). Some of the energy transferred is absorbed by living tissue and converted to heat, which in turn leads to thermoelastic expansion, which results in the emission of broadband (eg, z) ultrasonic waves. The ultrasonic wave generated in this way can be detected by the ultrasonic transducer to form an image.

<57>

On the other hand, optical absorption is closely related to physiological properties such as hemoglobin concentration and oxygen saturation. As a result, the magnitude of the ultrasonic emission (photoacoustic signal) is proportional to the local energy stack and can reveal physiologically characteristic light absorption contrast.

<59>

Light absorption in biological tissues is endogenous, such as hemoglobin or melanin.

(endogenous molecules) or may be due to contrast agents delivered externally. Blood is usually larger than the surrounding tissue Because of its large absorption in terms of surface, there can be sufficient internal contrast for optoacoustic images for viewing blood vessels. Thus, photoacoustic images can be used to monitor tumor angiogenesis in vivo, and can also be applied to blood oxygenation map ing and funcional brain imaging. have.

<61>

1 is a conceptual diagram illustrating an optoacoustic imaging apparatus 100 according to an embodiment of the present invention.

Referring to FIG. 1, the photoacoustic imaging apparatus 100 may include a probe 120 contacting a living tissue (C). In this case, the probe 120 may form an appearance to contact the living tissue (C).

<64>

The optoacoustic imaging apparatus 100 may include a laser emitter 110 installed inside the probe 120 to emit a laser having a specific wavelength to the outside. In this case, the laser generated by the laser emitter 110 may be emitted from the inside of the probe 120 through the optical fiber 111 to the outside.

<66>

The laser emitter 110 may emit lasers having different wavelengths. In addition, the laser emission unit 11 O may be formed of a Nd: Yag (neodymium doped yttrium aluminum garnet) laser barrier unit 110, but various kinds of lasers may be applied as necessary.

<68>

The laser emitter 110 is connected to an optical fiber or the like to convert the laser into a biological tissue.

We can investigate in (C). In this case, the laser irradiated from the laser emitter 110 may be emitted to the outside through the probe 120.

<70>

When the photoacoustic imaging apparatus loo irradiates a near-infrared laser to the biological tissue C through the laser emitter no, the biological tissue absorbing a short electromagnetic field of the laser is provided. The thermal expansion causes a wide range of ultrasonic waves, and may include a transducer 140 to sense the ultrasonic waves (hereinafter, referred to as photoacoustic signals) emitted. The transducer 140 may be installed inside the probe 120. In addition, the transducer 140 is emitted from the laser emitter 110 Can detect the photoacoustic signal generated by the laser of different wavelengths.

<72>

On the other hand, the transducer 140 according to an embodiment of the present invention can obtain a tomography image of the living tissue (C) by a back projection method.

<74>

On the other hand, the photoacoustic imaging apparatus 100 may include a controller 150 for generating a photoacoustic image of the biological tissue (C) and the oxygen saturation distribution of the biological tissue (C). In this case, the photoacoustic image may be generated based on the photoacoustic signal measured by the transducer 140, and the oxygen saturation distribution may be generated based on the photoacoustic signal.

<76>

The controller 150 may map and display the oxygen saturation distribution on the tissue image of the biological tissue C generated by the photoacoustic signal, and also display the laser emitter 110. Can be controlled. In detail, the controller 150 may control the frequency or intensity of the laser emitted from the laser emitter 110.

<78>

The optoacoustic imaging apparatus 100 may include an amplifier 160 installed between the transducer 140 and the controller 150 to amplify the optoacoustic signal measured by the transducer 140. In this case, the transducer 140, the amplifier 160, and the controller 150 may be connected by a cable (not shown) to transmit a signal. On the other hand, the operation of the optoacoustic imaging apparatus 100 will be described in detail below.

<80>

1. first step;

The living tissue (C) can be positioned to operate the optoacoustic imaging device (100). In this case, the biological tissue C may be placed on a separate support member (not shown) or disposed in the medium W through which the photoacoustic signal (ultrasound) can propagate. Hereinafter, for convenience of description, the case where the living tissue (C) is disposed in the medium (W) will be described in earnest.

<8>

The medium W may include a material capable of minimizing attenuation of the photoacoustic signal, such as water. In this case, when the transducer 140 and the probe 120 are integrally formed, the probe 120 may directly contact the living tissue C to obtain an image by the photoacoustic signal. May not be used. As described above, after positioning the living tissue (C), a laser having a specific wavelength may be irradiated onto the living tissue (C) through the laser emitting unit 110. In this case, the laser generated by the laser emitter 110 may be irradiated to the biological tissue C through the probe 120. In particular, the laser may be emitted from the laser emitter 110 and transmitted to the probe 120 through an optical fiber. The probe 120 may collect the laser and emit the laser to the outside.

<87>

When the laser is irradiated to the living tissue (C) as described above, the ultrasonic tissue is instantaneously generated by the thermal expansion in the living tissue (C) as described above. More specifically, when the laser is incident on the biological tissue (C), the heat energy is emitted to the surrounding tissues, and at this time, the surrounding tissues may generate an ultrasonic wave instantaneously by thermal expansion (thermoe last ic). In this case, the thermal relaxation time is different according to the characteristics of the biological tissue (C), so that the delay is reached with different delays. A tomographic image can be obtained by the same reverse projection method as in step 2.

<89>

_<90> the other hand, in the case such as the addition can enter the probe 120 to the internal organs through the case, the patient's mouth such that the probe 120 is formed in a form such as prototype. In this case, the tomography image may be obtained in the same manner as the mirror unit 231 rotates as the driving unit 232 is driven (see FIG. 2).

<91>

In particular, the ultrasonic waves generated in the biological tissue C by the irradiated laser may be detected by the transducer 140 in the same manner as the photoacoustic signal. Transducer 140 may be formed as a non-focused or focused transducer that can scan the optoacoustic signal. On the other hand, the photoacoustic signal generated in the living tissue (C) may be transmitted to the amplifier 160 through the transducer 140. The amplifier 160 may amplify the photoacoustic signal and transmit the amplified photoacoustic signal to the controller 150.

<93>

2. The second step;

The controller 150 performs biological tissue through photoacoustic imaging based on the photoacoustic signal.

The photoacoustic image of (C) can be generated. In more detail, the controller 150 obtains the photoacoustic signal through a LabVIEW program, and an algorithm may be implemented and operated. In this case, the algorithm is a light source of the laser emitter 110, a wavelength variable ORKoptical parametric oscillator, a method of irradiating the living tissue (C) from the laser emitter 110, and the light measured by the transducer 140 The sound signal may be programmed to synchronize the transmission of the sound signal to the controller 150 and the control of the driver. In particular, when the drive includes a stem motor (not shown), the programmed algorithm can set the movement speed, rotation angle per step, and total movement angle of the step motor, and measure the photoacoustic signal for each stem. It can be set to rotate automatically to the set target. In addition, the measured photoacoustic signal is transmitted to the controller 150, and the controller 150 may display the accumulated photoacoustic signal in intensity intensity graph and image as soon as the target angle is reached. The controller 150 may reconstruct the cross-sectional image of the biological tissue C from various angles by applying an algorithm for reconstructing the photoacoustic signal back to an image. In particular, the optoacoustic signal for reconstructing the image may be defined by Equation 1.

[Equation 1]

t = [r- r ₀ } / v _x

Where P ₀ is the initial photoacoustic signal, τ · is the coordinate vector of the image point to be obtained, r is the measured coordinate of the transducer 140, is the velocity of the ultrasonic wave, P ^ o ^ is the measured photoacoustic signal,。 is the entire surface and guharyeoneun point-in ^→ r _S0 lid angle in the direction in ^{di? 0} can be represented by equation (2).

Correction Paper (Rule 91) ISA / KR

Where ^？ ^ / ^ ^ can be obtained by Fourier inverse transform. In addition, ⁿ ° represents the unit vector of the vertical front when the bum on the surface of the living body C) in the laser source. Specifically, it can be obtained through [Equation 3].

[Equation 3]

Through the above process, it can be thrown along the 360 ° rotational direction to add all the cross-sectional images to form the original shape. At this time, the image may be displayed close to the original form through the correction process in the computation process, such as correction using a filter. 、

3. third step;

After the irradiation of the laser on the living tissue (C) as described above, the control unit 150 may control the laser emitting unit 110 to irradiate the laser of the biological wavelengths to the living tissue (C). In this case, the laser emitter 110 may emit a laser having a different wavelength to the outside by feeding back a trigger signal or the like to the controller 150. Specifically, when the biological tissue (C) is disposed as described above, the laser emitter 110 may be controlled by operating the controller 150. At this time, the laser emission unit 110 may generate the laser of a specific wavelength. The laser is basically a wavelength specification of 535nm and 1035nm, the fill width can be output at a repetition rate (repetit ion rate) of less than 6ns, 10Hz. In addition, the laser may have an energy density of 10 nJ / cm ² or less. At this time,

Correction Paper (Rule 91) ISA / KR The laser energy density may be set to 22mJ / cm ² or less ANSI ANSI standards.

<124>

In particular, a variable wavelength ORXoptical parametric oscillator may be configured to change the output wavelength of the laser generated by the laser emitter 110 so that the wavelength of the laser may be varied as necessary.

<126>

On the other hand, the laser emitted as described above is irradiated to the living tissue (C) can be absorbed part of the living tissue (C). In this case, the living tissue (C) may absorb the laser to form an absorption spectrum in the living tissue (C).

<128>

In detail, when the laser beams having different wavelengths are irradiated to the living tissue C, two photoacoustic images representing optical energy attenuation distributions according to wavelengths may be obtained. In this case, the two photoacoustic images may be represented by φ Μ ( _Γ ) and φ λ ² ( _Γ ), respectively.

<130>

On the other hand, it can be used as an element for correcting the photoacoustic image by specifying the average size of the strong scattering in the living tissue (C), in particular the strong scattering in the epidermis of the living tissue (C). In addition, the calibrated optoacoustic image shows two images representing the distribution of light absorption relative to the two wavelengths.

Can be expressed.

<132>

Therefore, by substituting the light absorption coefficient value and the molar absorption coefficient (value already obtained) into the above equation, the absolute oxygen saturation (S0 ₂ ) value and the relative total hemoglobin saturation (HbT) value in the image can be calculated. have.

<134>

Specifically, the absorption spectra of oxidized haemoglobin (Hb02) and reduced haemoglobin (Hb) may show a large difference in relative wavelengths. That is, the transducer is projected onto the biological tissue (C) to be measured by using a laser output in a wavelength section in which the concentration difference between the oxidized hemoglobin and the reduced hemoglobin is relatively large.

Using the relative difference of the photoacoustic signal obtained through 140 can be calculated through a test to calculate the optimal oxygen saturation value.

<136>

Correction Paper (Rule 91) ISA / KR Figure 3 shows the change in the oxidative haemoglobin absorption spectrum according to the wavelength change, in which red (solid line) represents the absorption coefficient of hemoglobin, and blue (dotted line) represents the absorption coefficient of reduced hemoglobin. Oxidized haemoglobin concentration may be defined by Equation 4 below.

[Equation 4] to f ^ ι ^ ᅀ — / ² ᅀ ^

^{_{m T = \ 2) + [}} Hb} = eu eu Λ _Λ2 _ΐ also be defined by the Equation 5] below is oxygen saturation.

[Equation 5]

\ ^> ₂ \ + \ Hb \ ᅳ ᅀ.

At this time, the optically oxidized haemoglobin saturation and oxygen saturation values are assumed to be the dominant light absorption elements at the wavelengths λΐ and λ2 of each laser, and the two wavelengths, Equations 4 and 5] can be used to calculate this. At this time, the meaning of each parameter is as follows.

^ ^1. ^ ² ： Molar absorption coefficient according to wavelength (unit: α ^η_1 )

^€ ^ ^€ mo ₂ : Mole absorptivity coefficient of oxidized hemoglobin and reduced haemoglobin (unit: cn ^"1 ) [Hb], [Hb0 ₂ ]: Saturation degree (molarity) in the form of duhemoglobin By irradiating two different wavelengths, λΐ and λ2, two optoacoustic images representing the optical energy attenuation distribution according to the wavelengths can be obtained, which can be expressed as # (r) and <? ^A2 (r), respectively. Here, the optical energy attenuation is related to the absorption coefficient and the laser light fluence at the r position, where the skin of the living tissue (C) has a homogeneous nature.

Correction Sheet (Rule 91) ISA / KR The variation of the laser reaching the internal tissue connection can also have a homogeneous distribution. Therefore, the molar extinction coefficient l. „Can be regarded as the main factor of the optical energy attenuation distribution.

<155>

On the other hand, the average size of the strong scattering in the skin or epidermis of the biological tissue (C) as described above can be used as an element for correcting the photoacoustic image. The photoacoustic image thus ^corrected may be two images μ (τ) and μ ^{Χ 2} (τ) ^' representing the relative light absorption distributions for each of the two wavelengths. Therefore, by substituting the light absorption coefficient value and the molar absorption coefficient (value already obtained) into the above equation, the absolute oxygen saturation (S02) estimated value and the relative total hemoglobin saturation (HbT) value can be obtained from the image.

<157>

<158> *

Finally, the relative extinction coefficients of oxidized hemoglobin and reduced hemoglobin for these wavelength ranges were calculated by measuring the photoacoustic signal in the blood sample, and this coefficient was calculated for the total hemoglobin in an in vivo experiment. Saturation and absolute oxygen saturation can be calculated and mapped to image pixel information.

<160>

On the other hand, in the case of mapping to image pixel information as described above, the brightness information of all pixels is converted between [0 1] in order to show the oxygen saturation distribution, and the value 1 is the value having the largest difference in the relative absorption coefficient. You can dare it. Specifically, the video coordinate to be mapped is

Rather than RGB (red, green, blue) coordinates, the coordinates may be expressed as HSV (hue, saturat ion, value or britness) coordinates. In this case, the H value may be set to 0 when the color is red, and the S value may be set to vary according to a change in the absorption coefficient of the pixel. Therefore, when the difference in absorption coefficient is increased, the red color becomes brighter, and when it is small, it may be set to darken. In addition, the V information may be treated to change the amplitude size of the optoacoustic signal, so that the oxygen saturation distribution and the histological image may be simultaneously observed.

<162>

On the other hand, the actual biological tissue (C) was experimented through the above device, the specific results will be described below.

<164>

1. Acquisition of photoacoustic ID signal and 2D video signal through fan team experiment

Correction Paper (Rule 91) ISA / KR <I66> Experimental materials can be prepared by inserting a black cable sheath with good absorption of the light source into the transparent gelatin to confirm the photoacoustic image. At this time, the black cable sheath can be prepared by inserting two or three in a triangular shape. In both cases, it is possible to experiment by placing a black cable sheath of diameter im inside a transparent gelatin sheath of 60 mm diameter.

<167>

The acquired photoacoustic signal is reconstructed into an image by applying a back projection algorithm. In the experiment, the signal acquisition is performed by 1.2 ^° per step, 300 steps (360 ^° ), and a sampling frequency of 40 MHz / s. In addition, considering the irradiation time of the laser and the propagation speed of the photoacoustic signal, only a signal corresponding to a period of 50 use can be stored as a signal after detecting the trigger signal for each step (angle).

<169>

FIG. 4 illustrates a case in which a phantom without a light absorbing material is used, and FIG. 5 illustrates a case in which a phantom in which a light absorbing material is present is used. When the two signals are compared based on the above picture, FIG. It can be seen that the signal in the picture without light absorbing material is not fluctuating generally and is flat, and the signal in the picture with light absorbing material inside the phantom is larger in amplitude than the signal in the picture without light absorbing material. You can see that the pattern appears.

<171>

6 to 8 are phantom experiments for comparing the accuracy of the size and spacing of the light absorbing material. Specifically, FIG. 6 shows the light absorbing phantom used, and FIG. 7 shows the obtained photoacoustic signal. 2D, and FIG. 8 shows the reconstructed image. The fan team used in the experiment was a transparent gelatin having a diameter of 60 mm 3, and a light absorbing rubber having a size as shown in FIG. 6 was inserted therein. The measured photoacoustic signal and the reconstructed image are lrai per horizontal and vertical per pixel.

<173>

6 to 8, comparing the accuracy of the magnitude of the photoacoustic signal restored after the experiment on the image restored from the photoacoustic signal obtained by irradiating the laser to the light absorption rubber phantom. It was. As a result of the experiment, the transparent gelatin and the black cable sheath have a lot of difference in light absorbency, so it can be confirmed that the reconstructed image is restored with little ambient noise. Specifically, the above-described contents can be clearly distinguished from FIG. 6 and FIG. 8. Also used in experiments It can be seen that the size of the table covering coincides with the phantom position in the reconstructed image.

<175>

<176> 2. Monitoring of wound healing process

In addition, the wound healing process may be confirmed through the photoacoustic image through the photoacoustic imaging apparatus 100 according to the exemplary embodiment. Specifically, in patients with a slow wound healing rate such as diabetes, the upper part of the wound coagulates, but a phantom experiment may be performed to image the healing process of the internal tissue that is covered.

<178>

9 shows an embodiment of the vascular phantom experiment, as shown in the figure, a red cable can be inserted in the form of blood vessels (thickness of 0.5 in the cylindrical gelatin having a diameter of 41 mm). ™ cable). While blood has a problem of spreading all when it touches water, the transducer can measure the photoacoustic signal only when there is a medium such as water, so as shown in the drawing, a blood vessel-shaped cable is placed near 10mm below the top of the fan team. By disposing, the upper part of the phantom containing blood is not submerged in water, and the transducers are submerged in water so that the change in the photoacoustic signal can be measured.

<180>

<i8i> In this case, one transducer 140 may be used to observe the vascular arch process. In addition, the transducer may be irradiated according to the order as described above.

The photoacoustic signal may be collected by the reverse projection algorithm while rotating the 140 to 360 degrees.

<182>

10 to 14 illustrate the results of the uneven test by the blood vessel phantom test, the test results will be described in detail with reference to the drawings. The result can be obtained by observing the photoacoustic image change over time.

<184>

FIG. 10 is an image of a fan team in a PAT state in which blood is not applied, and since the blood is not present on the upper surface, the shape of the cable made of blood vessels is well represented. In addition, Figure 11 shows a lot of noise as a whole, which is because the measured photoacoustic signal is so small that when the final normalization there is no significant difference in the size of the noise and photoacoustic signal results as described above.

<186> 12 and 13 are images obtained after 6 hours after 3 hours, respectively, and show little difference when compared with FIG. 11. More specifically, it can be seen that the appearance of blood vessels at the lower part of the blood is only slightly lighter, and no phenomenon appears.

<188>

FIG. 14 is an image measured after the blood is completely hardened, and all other conditions are the same, but the position is slightly moved during the experiment, and thus the result as described above is obtained. It can be seen that the part covered by is shown.

<190>

3. Experiment using dye to measure hemoglobin concentration and oxygen saturation distribution by photoacoustic signal acquisition

<1 2>

<193> hemoglobin concentration ^ hemoglobin oxygenat ion

Experiments using dyes can be performed to measure PAT. At this time, the experiment was performed in the following order to select which wavelength to use the two wavelengths used in the experiment.

<194>

FIG. 15 illustrates a phantom model using a dye, and FIG. 16 illustrates an image acquisition test result using a dye, which will be described in more detail with reference to the accompanying drawings.

<196>

^ 7> * First, Figure 15 is an experimental configuration of the fan team using a dye, put a red magenta dye inside the transparent tube, the intensity of the photoacoustic signal while increasing the wavelength at about 20nm intervals from 410nm to 750nm Measure the same, and proceed in the same way for cyan dye.

<198>

In this case, FIG. 16 shows the result.

In the vicinity of 510 nm, the amplitude of the red purple dye is stronger, and in the 650 nm of the red color system, the amplitude of cyan is stronger.

<200>

On the other hand, when the wavelength tunable laser emission unit 110 is used, the energy output depends on the wavelength. Although it depends, the dye experiment for calculating the hemoglobin concentration and the oxygen saturation distribution value does not need to compensate the above value, and thus does not require any additional compensation.

<202>

Meanwhile, as described above, based on the graph shown in FIG. 16, wavelengths of 510 nm and 610 ™ were used in an actual experiment. 17 to 20 show the test results of hemoglobin concentration when using the wavelengths of 510 nm and 610 nm, which will be described in more detail with reference to the drawings.

<204>

First, each dye is mixed at a ratio of 1: 1, 1: 3, and 3: 1, and then gradually distilled in water to observe a change until the dye ratio becomes 100% to 10%. Each point is a value obtained by averaging 100 samples.

<206>

<207>

17, 18, and 19 show graphs of 510 nm according to respective ratios.

It represents the ratio of the photoacoustic signal in 610nn. It is not an exact linear but represents a graph of increasing size overall. As a result, as the ratio of hemoglobin contained in the blood increases, the photoacoustic signal increases significantly.

<209>

20 shows a gradient depending on the concentration ratio of each dye with a group connecting the first point and the end point according to the ratio of each dye when the wavelength of the laser is 510 nm. In addition, when the starting points of the 510nm and 610nm graphs in the graphs of FIG. This can be seen that the light absorption rate is changed according to the ratio of each dye for the same reason as the slope difference in the graph shown in FIG.

<211>

<212> In addition, the amplitude graph of each dye according to wavelength shows reddish purple at 510nm.

(magenta) dye has a higher absorption rate, the difference is large in the graph of Figure 19 where the ratio of red purple dye is high, there is a moderate difference in the 1: 1 ratio graph, 1: 3 It can be seen that the amplitude is lower than when 610nm.

<213> <2! 4> FIG. 21 shows the results of experiments of oxygen saturation measurement, in which the amplitude change of the photoacoustic signal is shown when the ratio of red purple dye and cyan dye is changed. The results of experiments with changing the amplitude of the photoacoustic signal by gradually increasing the dye ratio are shown.

<215>

In the experiment shown in FIG. 21, the wavelengths of 510 nm and 610 nm were selected.

It is expected to increase gradually at 510nm wavelength and decrease at 610nm wavelength, but as shown in the figure, it can be seen that the tendency to decrease at both wavelengths in actual results.

<217>

However, it can be seen that the results as described above are also effective for the simulation of oxygen saturation because it can be seen that the result of the photoacoustic signal varies linearly according to the dye ratio.

<219>

FIG. 22 shows a phantom in which two red wires are embedded in gelatin. At this time, the size of the red wire inside the gelatin is 0.5 隱, the distance between the two lines is 1.8 瞧, the height is 13 睡. FIG. 23 is an optoacoustic image of the phantom illustrated in FIG. 22, and FIG. 24 is an enlarged image of the optoacoustic image illustrated in FIG. 23. As shown in the image, it can be seen that the measurement through the photoacoustic image is accurately represented in that the distance between the two points is measured to about 1.8 ms.

<221>

FIG. 25 illustrates an ultrasound image (a) obtained through the above experiment, and an image (b) mapping an optoacoustic image. More specifically, the ultrasound is performed by irradiating a laser to a fan team. The photoacoustic image (b) can be obtained by acquiring the image (a) and mapping the image obtained through the real-time PAT using Labview. The distance between the two wires in the ultrasound image was about 1.82 瞧. FIG. 26 is an enlarged image of the image illustrated in FIG. 25, and illustrates an image (b) in which an ultrasound image and a photoacoustic image are mapped.

<223>

Accordingly, when the photoacoustic imaging apparatus 100 according to the exemplary embodiment of the present invention is used, the controller 150 generates the photoacoustic image and oxygen saturation measured as described above. It can be displayed as one image.

<225>

Accordingly, the photoacoustic imaging apparatus 100 may be utilized for early diagnosis of degenerative joint disease using photoacoustic tomography. In addition, the photoacoustic imaging apparatus 100 can accurately identify the location of the cancer during prostate cancer diagnosis and surgery, and can be applied to early diagnosis of skin cancer and breast cancer.

<227>

In addition, the photoacoustic imaging apparatus 100 is applicable to a functional diagnostic field capable of simultaneously confirming anatomical and physiological information, and provides an apparatus for providing real-time images of oxygen saturation and tissue inside of tissues. It is possible to use as.

<22>

In particular, since the photoacoustic imaging apparatus 100 can obtain a sufficient image control for structural change of the biological tissue at the same time as measuring the oxygen saturation of the biological tissue, unlike the conventional method, according to the progression stage of the tissue disease Morphological diagnosis and progression of muscle disease and joint disease requiring detailed analysis may be possible.

<231>

In addition, when the photoacoustic imaging apparatus 100 is applied, the absorbance of the emitted laser is relatively higher than that of the normal tissue in hemoglobin-rich tissues or cancerous tissues. Compared to the organization, there is a characteristic that comes out large. Therefore, by applying these characteristics, an ultrasound echo image may be acquired for the same biological tissue, and then the optical acoustic image of the tissue may be embedded to provide anatomical information provided by the ultrasound image and the tissue provided by the photoacoustic image. By combining functional information, it is possible to provide more detailed information for diagnosis or surgery.

<233>

In addition, since the photoacoustic imaging apparatus 100 utilizes non-ionized electromagnetic radiation, the photoacoustic imaging apparatus 100 is harmless to the human body and is sensitive to abnormal living tissue because it depends on the absorption of near-infrared rays, thereby enabling early diagnosis of cancer.

<235>

The optoacoustic imaging apparatus 100 may combine the ultrasonic imaging method with the optoacoustic imaging method to correct a diagnostic image according to ultrasonic nonuniformity. In addition, the photoacoustic imaging device 100 is equally applicable to the diagnostic field applying the current ultrasonic diagnostic method, and when combined with existing ultrasonic equipment or optical diagnostic equipment such as OCT, It can be used as a diagnostic device of the type, and there is a technical advantage that it is efficient to accurately find the tissue structure surface of the boundary portion of the tumor.

<237>

2 is a conceptual diagram showing another example of an optoacoustic imaging apparatus 200 according to the present invention.

Referring to FIG. 2, the photoacoustic imaging apparatus 200 includes a laser emitter 210 and a probe.

220, the transducer 240, the controller 250, and the amplifier 260 may be included. In this case, the laser emitter 210, the probe 220, the transducer 240, the controller 250, and the amplifier 260 may be formed similarly to that described with reference to FIG. 1. Therefore, the following description will be made in detail with reference to FIG. 1 different from the above for convenience of description.

<240>

The probe 220 may be formed in a cylindrical shape. At this time, the photoacoustic imaging device

200 is rotatably installed on the probe 220 includes a rotary drive unit 230 for varying the path of the photoacoustic signal incident on the laser and the transducer 240 emitted from the laser emitter 210 can do.

<242>

In this case, the rotation driving unit 230 may include a mirror unit 231 for varying the laser and the photoacoustic signal, and a driving unit 232 for rotating the mirror unit 231. In addition, the photoacoustic imaging apparatus 200 may include a plastic membrane portion 270 formed on an outer circumferential surface of the probe 220 so that the laser and the photoacoustic signal pass. In this case, the plastic membrane portion 270 may be formed of a transparent material or the like so that the laser and the photoacoustic signal can pass.

<244>

On the other hand, with respect to the operation method of the optoacoustic imaging apparatus 200 in FIG.

Since it is performed similarly to the description, a detailed description thereof will be omitted below.

However, the photoacoustic imaging apparatus 200 according to another embodiment of the present invention measures the oxygen saturation of the biological tissue (C) and the image of the biological tissue (C) simultaneously by directly inserting and operating the organs of the body. can do.

<247>

In detail, when a signal is input through the control unit 250, the driving unit 232 may operate to rotate the mirror unit 231 by 360 ^° with a time difference inside the biological tissue C. In this case, the laser emitted through the laser emitter 210 is reflected by the mirror 231. Through the plastic membrane portion 270 may enter the living tissue (C).

<249>

The incident laser beam is absorbed by the living tissue C to generate an optoacoustic signal (ultrasound) as described above, and the optoacoustic signal is incident on the probe 220 and then through the mirror unit 231. May be incident to the transducer 240.

<25i>

The controller 250 may generate an optoacoustic image or an oxygen saturation image of the biological tissue C through the photoacoustic signal incident through the transducer 240. Therefore, since the photoacoustic imaging apparatus 200 utilizes non-ionized electromagnetic radiation, it is harmless to the human body and has a technical advantage of being sensitive to abnormal biological tissues to be used for early diagnosis of cancer because it depends on near-infrared absorption.

<253>

Although described and described with reference to the preferred embodiment for illustrating the technical spirit of the present invention above, the present invention is not limited to the configuration and operation as shown and described as described above, the scope of the technical spirit It will be understood by those skilled in the art that many changes and modifications can be made to the invention without departing from the scope thereof. Accordingly, all such suitable changes, modifications, and equivalents should be considered to be within the scope of the present invention.

Industrial Applicability

The present invention is an optoacoustic imaging apparatus capable of simultaneously monitoring the state of tissues by measuring oxygen saturation and tissue structure, which are physiological information of tissues, and capable of monitoring a patient's condition. Available to the appliance industry.

<256>

Claims

[Range of request]

[Claim 11

Probes;

A laser emitter installed in the probe and emitting a laser beam irradiated onto living tissue;

A transducer installed at the probe and configured to sense ultrasonic waves generated by thermoelastic expansion in the tissue irradiated with the laser; And

And a controller configured to generate a photoacoustic image and an oxygen saturation distribution of the biological tissue through the ultrasonic waves sensed by the transducer, and to map the generated photoacoustic image and the oxygen saturation distribution of the biological tissue. Photoacoustic imaging device using near infrared laser.

[Claim 2]

The method according to claim 1,

The laser emission unit is an optoacoustic imaging apparatus using a near infrared laser using a Nd: Yag laser.

[Claim 3]

The method according to claim 1,

The transducer is a photoacoustic imaging apparatus using a near-infrared laser to obtain a tomography image by a back projection method while rotating the living tissue.

[Claim 4]

The method according to claim 1,

And a rotatable drive unit rotatably installed on the probe to rotate the laser emitted from the laser emitter and a path of the ultrasonic wave incident on the transducer.

[Claim 5]

The method according to claim 4, The rotary drive unit,

A photoacoustic imaging apparatus using a near-infrared laser comprising a mirror for varying the path of the laser and the ultrasonic wave, and a driving unit for rotating the mirror.

[Claim 6]

The method according to claim 4,

The probe is formed in a cylindrical shape, the plastic membrane is disposed along the outer peripheral surface of the probe is disposed on the path of the laser to pass the laser Optoacoustic Imaging Apparatus Using Near Infrared Laser.

[Claim 7]

The method according to claim 1,

And an amplifier provided between the transducer and the control unit to amplify the ultrasonic waves detected by the transducer.

[Claim 8]

A laser irradiation step of irradiating a laser onto living tissue;

An ultrasonic sensing step of sensing ultrasonic waves generated by thermoelastic expansion in the tissue irradiated by the laser through a transducer;

An ultrasound image acquisition step of obtaining an ultrasound image of the biological tissue through the ultrasound sensed by the transducer;

An optoacoustic image acquisition step of obtaining an optoacoustic image of the biological tissue by receiving and imaging the ultrasonic wave sensed by the transducer; And

And a mapping step of mapping the ultrasound image and the photoacoustic image to obtain anatomical information as well as functional information of the biological tissue.