CN114469010A - Photoacoustic blood oxygen measuring device and method based on laser energy compensation technology - Google Patents

Abstract

The invention belongs to the technical field of photoacoustic imaging, and particularly relates to a photoacoustic blood oxygen measuring device and method based on a laser energy compensation technology. This signal is based on optoacoustic blood oxygen measuring device of laser energy compensation technique includes: the ultrasonic transducer, the spectroscope, the photoelectric detector and the processing module; the ultrasonic transducer is used for acquiring ultrasonic signals emitted by an object irradiated by the laser beam and transmitting the ultrasonic signals to the processing module; the spectroscope is used for separating a laser beam irradiating an object into a spectroscopic beam; the photoelectric detector acquires an energy intensity signal of the split light beam separated by the beam splitter and transmits the energy intensity signal to the processing module; and the processing module performs compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensation ultrasonic signal. The accuracy and reliability of the photoacoustic blood oxygen measurement can be improved.

Description

Photoacoustic blood oxygen measuring device and method based on laser energy compensation technology

Technical Field

The invention belongs to the technical field of photoacoustic imaging, and particularly relates to a photoacoustic blood oxygen measuring device and method based on a laser energy compensation technology.

Background

Photoacoustic imaging is a mixed mode bio/medical imaging method established based on the photoacoustic effect. In general, in photoacoustic imaging, a pulse laser is required to irradiate an imaging region (in particular, in thermoacoustic imaging, irradiation with a pulse laser of a radio frequency is used). A portion of the absorbed light energy is converted into heat energy, which causes thermo-elastic expansion of nearby tissue, thereby forming broadband (megahertz) ultrasound waves and emitting them all around. This ultrasonic wave can be detected with an ultrasonic transducer. And scanning detection in a certain range can be realized by moving the laser irradiation position. And (4) carrying out two-dimensional and three-dimensional image reconstruction on the detected signals by adopting a computer, thereby completing the photoacoustic imaging process.

One of the most important applications of photoacoustic imaging is the use of oxyhemoglobin (A)Oxyhemoglobin) And deoxyhemoglobin (c) (d)Deoxyhemoglobin) The blood oxygen saturation in blood is measured for the difference of the absorption coefficients of the laser light of different wavelengths. Compared with the conventional finger-clipped oximeter, the photoacoustic microscope has the following advantages:

1. can present 2 of blood oxygen concentration in tissueDOr even 3DA distribution diagram;

2. the accuracy is higher, and the error is smaller;

3. pulse independent, blood oxygen concentration in the vein can be measured;

4. the interference from the outside is less, such as skin color, fat skeleton, etc.

Compared with a blood oxygen measuring mode of blood drawing, the photoacoustic imaging measuring mode is non-invasive, real-time and long-term. Therefore, the method can be used for monitoring the blood oxygen saturation for a long time.

At present, the laser used for photoacoustic imaging and blood oxygen saturation measurement is generally a pulse laser with a laser pulse width of about 5-30 nanoseconds. Due to the complex laser and the complex structure of the external optical path, a certain energy difference exists between pulses. Such differences can lead to inaccuracies in the final blood oxygen measurements.

Disclosure of Invention

The invention aims to provide a photoacoustic blood oxygen measuring device and method based on a laser energy compensation technology so as to improve the accuracy and reliability of photoacoustic blood oxygen measurement.

In order to solve the above technical problem, the present invention provides a photoacoustic blood oxygen measuring apparatus based on laser energy compensation technology, which includes: the ultrasonic transducer, the spectroscope, the photoelectric detector and the processing module; the ultrasonic transducer is used for acquiring ultrasonic signals emitted by an object irradiated by the laser beam and transmitting the ultrasonic signals to the processing module; the spectroscope is used for separating a laser beam irradiating an object into a spectroscopic beam; the photoelectric detector acquires an energy intensity signal of the split beam separated by the beam splitter and transmits the energy intensity signal to the processing module; the processing module performs compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensation ultrasonic signal; wherein the processing module performs compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensated ultrasonic signal comprises: calibrating the energy intensity signal of the split beam; and compensating the ultrasonic signal according to the energy intensity signal of the calibrated split beam to obtain a compensated ultrasonic signal.

Further, the calibrating the energy intensity signal of the split beam of light includes:

wherein,PD_λto correspond to a wavelength ofλThe energy intensity signal of the split beam of the laser beam of (1);

PD_{λcalibrated ，}is the energy intensity signal of the calibrated split beam;Responsivity_λfor the photodetector at the wavelength of the laser beamλThe calibration factor of (2).

Further, the compensating the ultrasonic signal according to the energy intensity signal of the calibrated split beam to obtain a compensated ultrasonic signal includes:

wherein,PA_λto correspond to a wavelength ofλLaser beam ofThe ultrasonic signal of (3);PA_{λcompensated，}to compensate for the ultrasonic signal.

Further, the photoacoustic blood oxygen measuring apparatus further comprises: the processing module obtains the blood oxygen content percentage according to the compensation ultrasonic signals of two laser beams with different wavelengths:

wherein,C_HbRrefers to the concentration of hemoglobin;C_HbO2refers to the concentration of oxyhemoglobin;ε_HbR(λ) Refers to the wavelength of the laser beam of hemoglobinλThe molar extinction coefficient of;ε_HbO2(λ) Refers to oxyhemoglobin in laser beam wavelengthλThe molar extinction coefficient of;SOand 2 is the percent blood oxygen content.

Further, the wavelength combination of the two laser beams with different wavelengths may be 532nmAnd 559nmOr 532nmAnd 515nm。

In yet another aspect, the invention further provides a photoacoustic blood oxygen measurement method based on laser energy compensation technology, which is characterized in that,

acquiring an ultrasonic signal emitted by an object irradiated by a laser beam;

acquiring an energy intensity signal of a split beam of a laser beam;

compensating the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensated ultrasonic signal; wherein

The performing compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensated ultrasonic signal includes:

calibrating the energy intensity signal of the split beam:

；

compensating the ultrasonic signal according to the energy intensity signal of the calibrated split beam to obtain a compensated ultrasonic signal:

；

wherein,PD_λto correspond to a wavelength ofλThe energy intensity signal of the split beam of the laser beam of (1);PD_{λcalibrated，}is the energy intensity signal of the calibrated split beam;Responsivity_λfor the photodetector at the wavelength of the laser beamλThe calibration coefficient of (a);PA_λto correspond to a wavelength ofλThe ultrasonic signal of the laser beam of (1);PA_{λcompensated，}to compensate for the ultrasonic signal.

Further, the photoacoustic blood oxygen measuring method further comprises: obtaining the blood oxygen content percentage according to the compensation ultrasonic signals of two laser beams with different wavelengths:

wherein,C_HbRrefers to the concentration of hemoglobin;C_HbO2refers to the concentration of oxyhemoglobin;ε_HbR(λ) Refers to the wavelength of the laser beam of hemoglobinλThe molar extinction coefficient of;ε_HbO2(λ) Refers to oxyhemoglobin in laser beam wavelengthλThe molar extinction coefficient of;SOand 2 is the percent blood oxygen content.

Further, in the above-mentioned case,the wavelength combination of the two laser beams with different wavelengths may be 532nmAnd 559nmOr 532nmAnd 515nm。

The photoacoustic blood oxygen measuring device and the photoacoustic blood oxygen measuring method based on the laser energy compensation technology have the advantages that ultrasonic signals emitted by an object irradiated by the laser beams can be obtained, energy intensity signals of the split beams of the laser beams can be obtained, the ultrasonic signals are compensated according to the energy intensity signals of the split beams to obtain compensated ultrasonic signals, then the compensated ultrasonic signals are adopted to obtain the blood oxygen content percentage, and the accuracy and the reliability of photoacoustic blood oxygen measurement can be improved.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic diagram of a photoacoustic oximetry device based on laser energy compensation technology.

In the figure: the device comprises alaser beam 1, acoupling prism 2, anultrasonic transducer 3, aspectroscope 4, asplit beam 5, alaser power attenuator 6 and aphotoelectric detector 7.

Detailed Description

To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment provides a photoacoustic blood oxygen measuring device based on laser energy compensation technology, which comprises: the ultrasonic transducer, the spectroscope, the photoelectric detector and the processing module; the ultrasonic transducer is used for acquiring ultrasonic signals emitted by an object irradiated by the laser beam and transmitting the ultrasonic signals to the processing module; the spectroscope is used for separating a laser beam irradiating an object into a spectroscopic beam; the photoelectric detector acquires an energy intensity signal of the split beam separated by the beam splitter and transmits the energy intensity signal to the processing module; and the processing module performs compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensation ultrasonic signal.

In this embodiment, the processing module performing compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensated ultrasonic signal includes: calibrating the energy intensity signal of the split beam; and compensating the ultrasonic signal according to the energy intensity signal of the calibrated split beam to obtain a compensated ultrasonic signal.

In this embodiment, the calibrating the energy intensity signal of the split light beam includes:

wherein,PD_λto correspond to a wavelength ofλThe energy intensity signal of the split beam of the laser beam of (1);PD_{λcalibrated，}is the energy intensity signal of the calibrated split beam;Responsivity_λfor the photodetector at the wavelength of the laser beamλThe calibration factor of (2).

In this embodiment, compensating the ultrasonic signal according to the energy intensity signal of the collimated split beam to obtain a compensated ultrasonic signal includes:

wherein,PA_λto correspond to a wavelength ofλThe ultrasonic signal of the laser beam of (1);PA_{λcompensated，}to compensate for the ultrasonic signal.

In the present embodiment, as an alternative embodiment of the photoacoustic oximetry device to collect signals, as shown in fig. 1, alaser beam 1 is irradiated to an object through acoupling prism 2, so that the object locally generates vibration to excite ultrasonic waves; ultrasonic waves are transmitted to anultrasonic transducer 3 through acoupling prism 2, and theultrasonic transducer 3 transmits ultrasonic wave signalsPA_λThe data are converted into electric signals, are collected by a collecting system, and are transmitted to a processor module for photoacoustic imaging and oxyhemoglobin saturation measurement; thelaser beam 1 passes through thespectroscope 4 to separate a small part of energy, namely aspectroscope beam 5, and the power of the beam is far less than that of thelaser beam 1; however, when the power of thesplit beam 5 is still higher than the damage threshold of thephotodetector 7, thelaser power attenuator 6 may be added to attenuate the power of thesplit beam 5 again; so that the attenuated laser light can be measured by thephotodetector 7; measured by the photodetector 7PD_λThe system is collected by a collecting system, and the collected data is transmitted to a processor module for photoacoustic imaging and blood oxygen saturation measurement.

In this embodiment, the photoacoustic oximetry device further includes: the processing module obtains the blood oxygen content percentage according to the compensation ultrasonic signals of two laser beams with different wavelengths:

wherein,C_HbRrefers to the concentration of hemoglobin;C_HbO2refers to the concentration of oxyhemoglobin;ε_HbR(λ) Refers to the wavelength of the laser beam of hemoglobinλThe molar extinction coefficient of;ε_HbO2(λ) Refers to oxyhemoglobin in laser beam wavelengthλThe molar extinction coefficient of;SOand 2 is the percent blood oxygen content.

In this embodiment, preferably, the wavelength combination of the two laser beams with different wavelengths may be 532nmAnd 559nmOr 532nmAnd 515nm。

In the present embodiment, it is preferable that the wavelengths are respectivelyλ_xAndλ_ythe laser beam of (2) may be intermittently irradiated.

On the basis of the above embodiments, the present embodiment further provides a photoacoustic oximetry method based on a laser energy compensation technique, including: acquiring an ultrasonic signal emitted by an object irradiated by a laser beam; acquiring an energy intensity signal of a split beam of a laser beam; and performing compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensation ultrasonic signal.

In this embodiment, the performing compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensated ultrasonic signal includes:

calibrating the energy intensity signal of the split beam:

；

compensating the ultrasonic signal according to the energy intensity signal of the calibrated split beam to obtain a compensated ultrasonic signal:

；

wherein,PD_λto correspond to a wavelength ofλThe energy intensity signal of the split beam of the laser beam of (1);

PD_{λcalibrated ，}is the energy intensity signal of the calibrated split beam;Responsivity_λfor the photodetector at the wavelength of the laser beamλThe calibration coefficient of (a);PA_λto correspond to a wavelength ofλThe ultrasonic signal of the laser beam of (1);PA_{λcompensated，}to compensate for the ultrasonic signal.

In this embodiment, the photoacoustic oximetry method further includes: obtaining the blood oxygen content percentage according to the compensation ultrasonic signals of two laser beams with different wavelengths:

wherein,C_HbRrefers to the concentration of hemoglobin;C_HbO2refers to the concentration of oxyhemoglobin;ε_HbR(λ) Refers to the wavelength of the laser beam of hemoglobinλThe molar extinction coefficient of;ε_HbO2(λ) Refers to oxyhemoglobin in laser beam wavelengthλThe molar extinction coefficient of;SOand 2 is the percent blood oxygen content.

In this embodiment, the wavelength combination of the two laser beams with different wavelengths may be 532nmAnd 559nmOr 532nmAnd 515nm。

In the present embodiment, it is preferred that,Responsivity_λthe value mode under different wavelengths can correspond to the inquiry from the photoelectric converter of the corresponding model to the product official website; for example by usingTHORLAbSIs/are as followsPDA36A2, the following mode can be adopted:

wavelength-nm	Responsivityλ
		515	0.1825
532	0.2012
		559	0.2308

In the present embodiment, it is preferred that,ε_HbR(λ) Andε_HbO2(λ) At the laser beam wavelengthλThe lower molar extinction coefficient is a standard coefficient and can be obtained through query; in this embodiment, the following may be:

wavelength-nm	εHbR(λ)	εHbO2(λ)
			515	28681.6	20715.4
532	40584	43876
			559	53976	33034.6

In an alternative embodiment, wavelengths of the respective wavelengths are usedλ_x=532nm、λ_y=559nmIrradiating the laser beam at intervals;

respectively acquiring energy intensity signals of the calibrated split beams of the corresponding laser beams:

acquiring the compensation ultrasonic signal of the corresponding laser beam:

obtaining the percentage of blood oxygen content:

in the present embodiment, it is possible, alternatively,Responsivity_λhas the unit ofA/WIt is the relation of power and current under different wavelengths;ε_HbR(λ) Andε_HbO2(λ) Has the unit of

；PD_λAndPA_λmay be in the unit ofVThey can be collected by a collecting card in the form of voltage signals; the units of other intermediate values can be disregarded, because the last intermediate value participates in the division operation, and the unit parts which are excessive at last can be mutually offset; of course, one skilled in the art can also customize the units of the intermediate values as desired.

In summary, the photoacoustic blood oxygen measurement apparatus and method based on the laser energy compensation technology of the present invention can obtain the ultrasonic signal emitted by the object irradiated by the laser beam, obtain the energy intensity signal of the split beam of the laser beam, perform compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain the compensated ultrasonic signal, and then obtain the blood oxygen content percentage by using the compensated ultrasonic signal, so as to improve the accuracy and reliability of photoacoustic blood oxygen measurement.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims (8)

1. A photoacoustic blood oxygen measuring device based on laser energy compensation technology is characterized by comprising:

the ultrasonic transducer, the spectroscope, the photoelectric detector and the processing module;

the ultrasonic transducer is used for acquiring ultrasonic signals emitted by the object irradiated by the laser beam and transmitting the ultrasonic signals to the processing module;

the spectroscope is used for separating a laser beam irradiating an object into a spectroscopic beam;

the photoelectric detector acquires an energy intensity signal of the split beam separated by the beam splitter and transmits the energy intensity signal to the processing module;

the processing module performs compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensation ultrasonic signal; wherein

The processing module performs compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensated ultrasonic signal, and the compensation processing comprises:

calibrating the energy intensity signal of the split beam;

and compensating the ultrasonic signal according to the energy intensity signal of the calibrated split beam to obtain a compensated ultrasonic signal.

2. The photoacoustic oximetry device of claim 1,

the calibrating the energy intensity signal of the split beam of light comprises:

wherein,PD_λto correspond to a wavelength ofλThe energy intensity signal of the split beam of the laser beam of (1);

PD_{λcalibrated ，}is the energy intensity signal of the calibrated split beam;Responsivity_λfor the photodetector at the wavelength of the laser beamλThe calibration factor of (2).

3. The photoacoustic oximetry device of claim 2,

compensating the ultrasonic signal according to the energy intensity signal of the calibrated split beam to obtain a compensated ultrasonic signal comprises:

wherein,PA_λto correspond to a wavelength ofλThe ultrasonic signal of the laser beam of (1);PA_{λcompensated，}to compensate for the ultrasonic signal.

4. The photoacoustic oximetry device of claim 3, further comprising:

the processing module obtains the blood oxygen content percentage according to the compensation ultrasonic signals of two laser beams with different wavelengths:

wherein,C_HbRrefers to the concentration of hemoglobin;C_HbO2refers to the concentration of oxyhemoglobin;ε_HbR(λ) Refers to the wavelength of the laser beam of hemoglobinλThe molar extinction coefficient of;ε_HbO2(λ) Refers to oxyhemoglobin in laser beam wavelengthλThe molar extinction coefficient of;SOand 2 is the percent blood oxygen content.

5. The photoacoustic oximetry device of claim 4,

the wavelength combination of the two laser beams with different wavelengths may be 532nmAnd 559nmOr 532nmAnd 515nm。

6. A photoacoustic blood oxygen measuring method based on a laser energy compensation technology is characterized by comprising the following steps:

acquiring an ultrasonic signal emitted by an object irradiated by a laser beam;

acquiring an energy intensity signal of a split beam of a laser beam;

compensating the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensated ultrasonic signal; wherein

The performing compensation processing on the ultrasonic signal according to the energy intensity signal of the split beam to obtain a compensated ultrasonic signal includes:

calibrating the energy intensity signal of the split beam:

；

compensating the ultrasonic signal according to the energy intensity signal of the calibrated split beam to obtain a compensated ultrasonic signal:

；

wherein,PD_λto correspond to a wavelength ofλThe energy intensity signal of the split beam of the laser beam of (1);

PD_{λcalibrated ，}is the energy intensity signal of the calibrated split beam;Responsivity_λfor the photodetector at the wavelength of the laser beamλThe calibration coefficient of (a);PA_λto correspond to a wavelength ofλThe ultrasonic signal of the laser beam of (1);PA_{λcompensated，}to compensate for the ultrasonic signal.

7. The photoacoustic oximetry method of claim 6, further comprising:

obtaining the blood oxygen content percentage according to the compensation ultrasonic signals of two laser beams with different wavelengths:

wherein,C_HbRrefers to the concentration of hemoglobin;C_HbO2refers to the concentration of oxyhemoglobin;ε_HbR(λ) Refers to the wavelength of the laser beam of hemoglobinλThe molar extinction coefficient of;ε_HbO2(λ) Refers to oxyhemoglobin in laser beam wavelengthλThe molar extinction coefficient of;SOand 2 is the percent blood oxygen content.

8. The photoacoustic oximetry method of claim 7,

the wavelength combination of the two laser beams with different wavelengths may be 532nmAnd 559nmOr 532nmAnd 515nm。

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