CN106691391B - Lateral scanning photoacoustic imaging method and device for prostate - Google Patents
Lateral scanning photoacoustic imaging method and device for prostate Download PDFInfo
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- CN106691391B CN106691391B CN201710071221.1A CN201710071221A CN106691391B CN 106691391 B CN106691391 B CN 106691391B CN 201710071221 A CN201710071221 A CN 201710071221A CN 106691391 B CN106691391 B CN 106691391B
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
- A61B5/0082—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes
- A61B5/0084—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes for introduction into the body, e.g. by catheters
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/08—Detecting organic movements or changes, e.g. tumours, cysts, swellings
- A61B8/0833—Detecting organic movements or changes, e.g. tumours, cysts, swellings involving detecting or locating foreign bodies or organic structures
- A61B8/085—Detecting organic movements or changes, e.g. tumours, cysts, swellings involving detecting or locating foreign bodies or organic structures for locating body or organic structures, e.g. tumours, calculi, blood vessels, nodules
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/44—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device
- A61B8/4483—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer
Abstract
The invention provides a lateral scanning photoacoustic imaging method and device for a prostate, wherein the device comprises a lateral signal excitation source and a lateral signal receiving device, and the lateral signal excitation source comprises an optical fiber, a reflecting mirror, a catheter and a pulse laser light source; the tail end of the catheter is a lateral light-transmitting light emitting end, and a reflecting mirror is arranged at the tail end of the light emitting end; an optical fiber is arranged in the catheter lumen, and the output end of the optical fiber is adjacent to the reflector and points to the reflector; when the device works, the guide tube is rotated to enable the reflecting mirror to face the tissue to be scanned, the light source emits pulse laser through the optical fiber and the reflecting mirror to enable the tissue to be scanned to generate a photoinduced ultrasonic signal, and the lateral signal receiving device generates a scanning image according to the signal; the invention can perform nondestructive inward side-emitting type large-range light irradiation on the prostate tissue through the urethra with better light intensity, and can realize large-range and large-depth three-dimensional photoacoustic imaging through the scanning detection of the side-direction long focal area ultrasonic transducer arranged in the rectum to expand the noninvasive ultrasonic receiving operation.
Description
Technical Field
The invention relates to medical diagnosis equipment, in particular to a lateral scanning photoacoustic imaging method and device for a prostate.
Background
The shape of the prostate is like an inverted chestnut with a slightly flat front and back, the prostate is positioned between the bladder and the genitals of the urethra, is deeply hidden in the pelvis, is pasted with pubic symphysis at the front and is worn with the urethra at the middle of the rear according to the rectum, so that the characteristics of hidden position and difficult examination of the prostate are determined. The application of photoacoustic imaging technology in early detection of prostate tumor inevitably solves two problems: deep penetration, omnibearing non-invasive photo-acoustic excitation and non-damage ultrasonic detection.
The focusing photoacoustic scan imaging uses short pulse laser to irradiate tissue at a certain repetition frequency, and ultrasonic signals generated by light absorption and adiabatic expansion can be received by a focusing ultrasonic transducer positioned on the surface of the tissue after being propagated in the tissue. The focusing ultrasonic transducer has the characteristic of good response to the photoacoustic signals in the focal region, and the collected ultrasonic signals mainly originate from the focal region, so that the focal region of the ultrasonic transducer is scanned point by point to form a tissue body, and the longitudinal photoacoustic signals at a plurality of positions are combined to obtain a two-dimensional light absorption diagram of the tissue body. The spatial resolution of this approach depends on the focal spot size of the transducer. When the focusing transducer is a probe of a long focal zone, the one-dimensional time resolution photoacoustic signal in the focusing axial direction of the transducer can be utilized to reversely push out the light energy absorption distribution of a tissue body in the focusing axial direction of the ultrasonic transducer, and a plurality of longitudinal signals obtained by transverse scanning of an axial orthogonal plane are combined to form a three-dimensional image, so that the three-dimensional image has the characteristic of simple imaging algorithm. The lateral resolution of such an image is still dependent on the focal spot size of the transducer; the longitudinal resolution is then determined by the frequency range of the photoacoustic signal and the response time of the ultrasound transducer.
For the prostate, the imaging quality of photoacoustic scan imaging depends on the irradiation mode to a great extent, for example, when light irradiation is performed outside the gland (abdomen or rectum), the light is easily attenuated by serious light of peripheral tissues to cause insufficient light penetration depth, especially the distance between the gland on one side of the urethra and an external irradiation light source is large, the light absorption energy is seriously reduced, and effective photoacoustic excitation is difficult to perform; while transurethral internal light irradiation allows for more adequate light energy absorption within the prostate tissue, a larger range of internal light absorption distribution, in fact, transurethral light transmission has been widely used for photodynamic therapy of the prostate, indicating that transurethral internal photoacoustic excitation is of great clinical feasibility.
The technical principle method of the photoacoustic nondestructive detection of the prostate tumor by the light irradiation in the urethra is that a lateral signal excitation source is inserted into and irradiates the prostate through the urethra, ultrasonic signals with different intensities are generated in the normal gland tissue with weaker absorption and the tumor region with stronger absorption, and the propagation speed of light in the tissue is far higher than the sound velocity in the tissue body, so that the photoacoustic signals generated by the absorber in the sample can be basically regarded as being excited simultaneously. The distance between the absorber and the probe at different positions is different, and the generated photoacoustic signals are received by the probe after different time delays, so that the position of the target absorber can be determined by the propagation time of the photoacoustic signals; in addition, the amplitude of the photoacoustic signal is directly related to the light energy absorption degree of the target absorber, and therefore the light energy absorption condition of the target absorber can also be known from the amplitude value of the photoacoustic signal. The photoacoustic signal generated by the prostate tumor can fully utilize the adjacent rectum space at the rear side, and the lateral long focal zone focusing ultrasonic transducer is placed in the rectum for endoscopic nondestructive detection. The transducer firstly performs axial sector scanning detection on a certain axial position, and then the rotating positioning device rotates the catheter to change the irradiation direction of the pulse laser so as to generate an ultrasonic signal with a new direction; the signal receiving device is driven by the rotating stepping motor to perform sector scanning detection. The output electric signal containing the radial time-resolved ultrasonic information is amplified and filtered by an amplifier, then is input into an oscilloscope and is processed by a computer, and the computer generates and splices scanning images according to multi-azimuth ultrasonic signals to realize omnidirectional two-dimensional imaging of tissues to be scanned. The signal receiving device is driven by the electric control translation stage to generate axial translation, and fan rotation scanning under multidirectional irradiation is continuously performed on the signal receiving device at a new axial position, so that axial fan scanning and axial translation scanning of the prostate and peripheral tissues can be completed, the acquisition of three-dimensional light energy deposition distribution data of the whole sample is realized, and a functional imaging diagram of the prostate tissues containing physiological and pathological information is obtained. Because the focusing transducer based on the long focal zone detects the photoacoustic signal, a longer effective imaging area can be obtained without adjusting the longitudinal position of the transducer, thereby facilitating the realization of photoacoustic imaging of deeper tissues; thus, the medical worker can realize the atraumatic external detection of the prostate cancer with hidden focus.
However, detection of deeper tissues requires scanning imaging techniques with sufficient imaging depth, meaning that sufficient illumination intensity must be ensured on the target being scanned. At present, the photoacoustic excitation adopted by a photoacoustic imaging system for the prostate is mostly irradiated through the abdomen or rectum, and the in-vivo excitation mode adopting a dispersion optical fiber leads to weaker illumination energy on a target detection surface due to light path dispersion, so that the penetration depth of single side light is insufficient during the same energy input, and the imaging depth of single side is easy to influence; in addition, some of the lateral old systems have small light irradiation area, so that the time is required to rotate the light source for many times in the experiment to ensure that all the absorbers are observed, and the scanning efficiency is seriously influenced; in addition, when the photoacoustic detection is performed on the prostate, the rectum space is the place of the first-choice ultrasonic signal receiver, the array type ultrasonic transducer is limited by the rectum space, only limited-angle signal acquisition can be performed, enough data are difficult to obtain, imaging depth and accuracy are easy to influence, and great difficulty is brought to image reconstruction. If the receiver needs to be subjected to large-distance transverse displacement during detection to adjust the detection direction for receiving signals of the new direction, serious discomfort of detected personnel can be caused; how to solve the problems of deep penetration, omnibearing non-invasive photoacoustic excitation and nondestructive ultrasonic detection is an important research direction.
Disclosure of Invention
The invention provides a lateral scanning photoacoustic imaging method and device for a prostate, which can perform nondestructive inward lateral light-emitting type large-range scanning light irradiation on human body prostate tissue through urethra with better light intensity, and can realize large-range and large-depth three-dimensional photoacoustic imaging through ultrasonic noninvasive scanning detection of a lateral long-focal-area ultrasonic transducer arranged in human body rectum.
The invention adopts the following technical scheme.
A lateral scanning photoacoustic imaging method and device for a prostate, wherein the lateral scanning photoacoustic imaging device comprises a lateral signal excitation source and a lateral signal receiving device, and the lateral signal excitation source comprises an optical fiber, a reflecting mirror, a catheter and a pulse laser light source; the catheter is a detection catheter which can be inserted into a part to be detected; the tail end of the catheter is a light emitting end capable of laterally transmitting light, and a reflecting mirror which is arranged at an oblique angle with the catheter is arranged at the tail end of the light emitting end; the initial end of the conduit is connected with the rotary positioning device; an optical fiber is arranged in the catheter lumen, and the input end of the optical fiber is connected with a pulse laser light source; the optical fiber output end is positioned at the light emitting end and adjacent to the reflector, the tip of the optical fiber output end is polished to be vertical to the optical fiber body, and the light emitting direction of the optical fiber output end points to the reflector; the lateral signal receiving device is a lateral water immersion type long focal zone focusing ultrasonic receiving device; when the lateral scanning photoacoustic imaging device works, the rotary positioning device rotates the guide tube to enable the reflecting mirror to face the tissue to be scanned, and the pulse laser source emits pulse laser to the tissue to be scanned through the optical fiber and the reflecting mirror to enable the tissue to be scanned to generate a photoinduced ultrasonic signal; the direction of the reflecting mirror which is arranged at an oblique angle with the guide pipe is changed according to the requirement; the signal receiving device receives signals generated under the irradiation of all directions in a sector scanning mode and sends the signals to an external computer, and the computer generates unidirectional or spliced all-directional two-dimensional images of an XY plane according to the signals; the signal receiving end of the lateral signal receiving device is arranged on the translation stage, and when the signal receiving end moves on the Z axis to change the receiving position, an external computer processes the signals of the new and old receiving positions to realize three-dimensional photoacoustic imaging on the XYZ axis of the scanning target.
The optical fiber is an end-emitting multimode optical fiber, and a reflecting mirror which is arranged at an angle of 45 degrees with the catheter is arranged at the tip of the light emitting end.
The outer diameter range of the catheter is the same as that of a common medical catheter.
The lateral signal receiving device is a lateral water immersion type long focal zone focusing ultrasonic transducer.
The translation stage is an electric control translation stage, the electric control translation stage is loaded with a rotary stepping motor, a signal receiving end of the lateral signal receiving device is connected with the rotary stepping motor, the rotary stepping motor changes the receiving direction of the signal receiving end, and the electric control translation stage is loaded with the signal receiving end to move on the Z axis.
The working method for performing lateral scanning photoacoustic imaging on the human prostate by the lateral scanning photoacoustic imaging device sequentially comprises the following steps of;
a1, inserting a catheter into a prostate part of a human body through a catheter or directly inserting the catheter into the prostate part of the human body through a urethra, enabling a light emitting end of the catheter to be positioned beside a tissue to be scanned, and inserting a signal receiving end of a lateral signal receiving device into a rectum of the human body to perform an extraglandular noninvasive ultrasonic receiving operation;
a2, rotating the catheter by the rotary positioning device to enable the light emitting direction of the reflector to face to tissues to be scanned beside the light emitting end of the catheter;
a3, the pulse laser source emits pulse laser to the tissue to be scanned through the optical fiber and the reflecting mirror, so that the tissue to be scanned generates a photoinduced ultrasonic signal;
a4, the signal receiving end receives ultrasonic signals, and meanwhile, the lateral signal receiving device changes the direction of the signal receiving end under a static state so as to realize a signal receiving surface of a sector track, the signal receiving device transmits received ultrasonic signal data to an external computer, and the computer generates a single-direction scanning image according to the ultrasonic signals;
a5, rotating the catheter by the rotary positioning device to change the irradiation direction of the pulse laser, continuing the fan surface at the original position by the signal receiving end of the lateral signal receiving device to receive the ultrasonic signal generated by the new irradiation direction, transmitting the data to an external computer, generating a scanning image of the new direction by the computer according to the ultrasonic signal, and splicing the scanning image until an omnibearing two-dimensional image is obtained;
a6, the lateral signal receiving device is driven by the electric control translation stage to move to a new position on the Z axis, the fan-shaped receiving is carried out on the ultrasonic scanning signals generated under the multidirectional irradiation on the XY axis plane, the computer generates and splices a new omnibearing two-dimensional scanning image according to all ultrasonic signals received by the signal receiving end of the lateral signal receiving device at the new position, and then the combined processing is carried out on the ultrasonic scanning signals and the two-dimensional image data obtained in the step A5 to generate the three-dimensional imaging of the XYZ axis of the tissue to be scanned.
The ultrasonic signals received by the transducer are subjected to amplitude limiting, shaping, filtering and amplifying by the ultrasonic pulse receiver and then sent to the digital oscilloscope, and the digital oscilloscope carries out multiple average processing on the ultrasonic signals and then sends the processed data to the computer through the GPIB card.
The distance between the optical fiber output end and the reflecting mirror is 5mm, and the optical fiber output end and the reflecting mirror are fixed by an adhesive.
The pulse laser source is an OPO pulse laser capable of outputting continuous adjustable pulse laser with 680-1000nm wave band or independently outputting 532nm or 1064nm wave band pulse laser, the pulse width is 6-8ns, the single pulse energy is about 4mJ, and the repetition frequency is 10Hz, and the pulse laser inputs laser to the optical fiber through the optical coupler.
In the invention, the lateral signal excitation source comprises an end-fire type end-fire multimode fiber (numerical aperture 0.25, diameter 1.5 mm) and a 45-degree inclined reflector and guide tube; the tail end of the optical fiber is polished flat and perpendicular to the optical axis, and the tail end of the optical fiber is separated from the reflector by a distance of about 5mm, so that the light spot reaching the reflector is larger due to a certain divergence angle (29 degrees) of the output light of the optical fiber, and after the light spot is further amplified by the reflection effect of the oblique angle reflector, the light beam irradiates the tissue sample in a direction almost perpendicular to the optical fiber, thereby being beneficial to realizing lateral irradiation of the larger light spot (with the diameter of 5 mm); due to the characteristics of the lateral light source, such as better reflected light intensity and small light energy loss of the reflector, the photoacoustic signal intensity of the area needing to be scanned is improved, so that the method is more suitable for diagnosis occasions needing to be further confirmed, wherein the tumor azimuth is approximately known.
In the invention, only the key area can be conveniently scanned, and the catheter is only required to be rotated to a preset angle, so that the receiving end of the ultrasonic receiving device is not required to be integrally and transversely moved, thereby improving the scanning speed; when doctors only concern about the distribution of the absorber on one side of the urethra and do not want to know the information of all absorbers around the urethra, the single-side imaging characteristic of the invention can better meet the requirement of diagnosis and scanning on key areas.
In the invention, the tip of the optical fiber output end is polished to be vertical to the optical fiber body, and the light emitting direction of the optical fiber output end points to the reflector; the design ensures that the emergent light of the optical fiber output end is more neat, reduces the emergent light dispersion caused by an irregular plane, and is beneficial to improving the emergent light intensity.
In the invention, the lateral signal receiving device is a lateral water immersion type long focal zone focusing ultrasonic transducer; because the focusing ultrasonic transducer has the characteristics of good response to the photoacoustic signals in the focal region and almost zero response to the photoacoustic signals outside the focal region, the acquired ultrasonic signals mainly originate from the region where the focus is located, so that the focal region of the ultrasonic transducer scans the tissue body point by point, and a two-dimensional light absorption diagram of the tissue body can be obtained by combining longitudinal photoacoustic signals at a plurality of positions; when the invention carries out lateral photoacoustic imaging on the prostate tissue body, firstly, a catheter rotates to a preset angle, a lateral long focal zone ultrasonic transducer carries out axial sector scanning detection on a certain axial position, and an output electric signal containing radial time-resolved ultrasonic information is amplified and filtered by an amplifier, then is input into an oscilloscope and is processed by a computer; after that, the rotation positioning device rotates to change the irradiation direction of the catheter, and the computer continues to drive the lateral signal receiving device to perform sector scanning detection of the photoacoustic signal with the new direction. The computer generates scanning images according to ultrasonic signals generated under multidirectional irradiation and splices the scanning images to realize omnidirectional two-dimensional imaging of tissues to be scanned; the lateral signal receiving device can perform axial translation through the two-dimensional translation of the electric control translation table, and continuously perform axial scanning detection under multi-azimuth irradiation on a new axial position, so that acquisition of three-dimensional light energy deposition distribution data of a whole prostate sample can be completed, a functional imaging diagram of the prostate tissue containing physiological and pathological information is obtained, and the lateral imaging method can realize multi-angle detection of a scanning target, so that imaging is more reliable; in addition, since the prostate is one of the smallest organs of the human body, the output light intensity and the range of the device are ensured, and when the device is used for detection, the ultrasonic receiving device in the long focal zone in the rectum can cover the whole tissue only by small axial displacement in the rectum, so that the problem that the conventional medical array ultrasonic transducer can only collect the photoacoustic signals with limited angles to cause image reconstruction to have difficult and complicated performance is solved, the transverse receiving position of the ultrasonic receiving device does not need to be changed, and the examination discomfort of an inspector can be greatly reduced.
Compared with the traditional optical fiber light source, the invention has the advantages of simplicity, easy preparation, low cost and simple manufacture, is beneficial to imaging an absorber in a larger range and depth of the irradiation direction, and can solve the problem that the existing columnar dispersion optical fiber has weaker lateral light extraction rate, and is easy to cause insufficient single-side light penetration depth to influence the single-side imaging depth; compared with the existing lateral light source based on the total reflection principle of light, the lateral light source can avoid the defect that the light source needs to be rotated for many times in experiments due to small irradiation light points so as to ensure that all absorbers are observed.
When the lateral light source designed by the invention is used for in-vivo photoacoustic excitation, the lateral light source has better positioning capability and imaging capability on the absorber, the imaging range of a single side is larger, the advantage of imaging the lateral light source on the single side is fully described, and in specific imaging operation, an operator can change the imaging of the absorber in other directions through the rotation of the lateral light source; considering that early prostate cancer is mostly generated in the peripheral zone of the prostate, that is to say, behind the prostate, the lateral light source is expected to become a novel light source structure in the early prostate cancer photoacoustic imaging technology, and has important value.
Drawings
The invention is described in further detail below with reference to the attached drawings and detailed description:
FIG. 1 is a schematic diagram of an imaging apparatus of the present invention;
FIG. 2 is a schematic view of the light emission end of the catheter of the present invention;
FIG. 3 is a schematic view of the light emission from the other direction of the light emitting end of the catheter of the present invention;
FIG. 4 is a schematic illustration of a cut-away view of an optical fiber and mirror of the present invention;
FIG. 5 is a schematic representation of the imaging results of the present invention;
FIG. 6 is another schematic representation of the imaging results of the present invention;
in the figure: 1-a pulsed laser light source; 2-a catheter; 3-the light emitting end of the catheter; 4-lateral signal receiving means (focused tele ultrasonic receiving means); 5-rectum; 6-urethra or urinary catheter; 7-tissue to be scanned (prostate tumor); 8-an electric control translation stage; 9-rotating a stepper motor; 10-a computer; 11-a mirror; 12-optical fiber; 13-a digital oscilloscope; 14-rotating a rotating shaft of the stepper motor; 15-a rotational positioning device.
Detailed Description
As shown in fig. 1-6; a lateral scanning photoacoustic imaging method and device for a prostate, wherein the lateral scanning photoacoustic imaging device comprises a lateral signal excitation source and a lateral signal receiving device, the lateral signal excitation source comprises an optical fiber 12, a reflecting mirror 11, a catheter 2 and a pulse laser light source 1; the catheter 2 is a detection catheter which can be inserted into a part to be detected; the tail end of the catheter 2 is a light emitting end 3 capable of transmitting light laterally, and a reflector 11 which is arranged at an oblique angle with the catheter is arranged at the tip of the light emitting end 3; the beginning end of the conduit 2 is connected with a rotary positioning device; an optical fiber 12 is arranged in the catheter lumen, and the input end of the optical fiber 12 is connected with the pulse laser light source 1; the optical fiber output end is positioned at the light emitting end and adjacent to the reflecting mirror 11, the tip of the optical fiber output end is polished to be vertical to the optical fiber 12 body, and the light emitting direction of the optical fiber output end points to the reflecting mirror 11; the lateral signal receiving device is a lateral water immersion type long focal zone focusing ultrasonic receiving device 4; when the lateral scanning photoacoustic imaging device works, the rotary positioning device rotates the guide tube 2 to enable the reflecting mirror 11 to face the tissue to be scanned, and the pulse laser light source emits pulse laser to the tissue 7 to be scanned through the optical fiber 12 and the reflecting mirror 11 to enable the tissue 7 to be scanned to generate a photoinduced ultrasonic signal; the direction of the reflecting mirror which is arranged at an oblique angle with the guide pipe is changed according to the requirement; the signal receiving device receives signals generated under the irradiation of all directions in a sector scanning mode and sends the signals to an external computer, and the computer generates unidirectional or spliced all-directional two-dimensional images of an XY plane according to the signals; the signal receiving end of the lateral signal receiving device is arranged on the translation stage, and when the signal receiving end moves on the Z axis to change the receiving position, an external computer processes the signals of the new and old receiving positions to realize three-dimensional photoacoustic imaging on the XYZ axis of the scanning target.
The optical fiber 12 is an end-emitting multimode optical fiber, and a reflecting mirror 11 which is arranged at an angle of 45 degrees with the catheter 2 is arranged at the tip of the light emitting end 3.
The outer diameter range of the catheter 2 is the same as that of the common medical catheter 6.
The lateral signal receiving device is a lateral water immersion type long focal zone focusing ultrasonic transducer.
The translation stage is an electric control translation stage, the electric control translation stage is loaded with a rotary stepping motor 9, a signal receiving end of the lateral signal receiving device is connected with the rotary stepping motor (connected with a rotating shaft 14), the rotary stepping motor changes the receiving direction of the signal receiving end, and the electric control translation stage bears the signal receiving end to move on a Z axis.
In the example, the electric control translation stage is fixed in the sleeve, the electric control translation stage is connected with the miniature rotary stepping motor through the screw rod, the ultrasonic transducer is fixed on the motor shaft of the miniature rotary motor, the sleeve wall below the ultrasonic transducer is a sound-transmitting window with the thickness of 0.5mm, the axial length of the sound-transmitting window is 40mm, and the opening angle of the sound-transmitting window to the motor shaft is 60 degrees. The whole body is encapsulated in the sleeve.
The working method for performing lateral scanning photoacoustic imaging on the human prostate by the lateral scanning photoacoustic imaging device sequentially comprises the following steps of;
a1, inserting the catheter 2 into the prostate part of a human body through the catheter 6 or directly through the urethra, enabling the light emitting end of the catheter to be positioned beside the tissue to be scanned, and inserting the signal receiving end of the lateral signal receiving device into the rectum of the human body to perform the non-invasive ultrasound receiving operation outside the gland;
a2, the rotary positioning device rotates the catheter 2 to enable the light emitting direction of the reflecting mirror 11 to face the tissue 7 to be scanned beside the light emitting end 3 of the catheter;
a3, the pulse laser source 1 emits pulse laser to the tissue 7 to be scanned through the optical fiber 12 and the reflecting mirror 11, so that the tissue 7 to be scanned generates an ultrasonic signal;
a4, the signal receiving end receives ultrasonic signals, and meanwhile, the lateral signal receiving device changes the direction of the signal receiving end under a static state to realize a signal receiving surface (a fan shape is a shaft fan shape) of a fan-shaped track, the signal receiving device transmits received ultrasonic signal data to an external computer, and the computer generates a single-direction scanning image according to the ultrasonic signals;
a5, rotating the catheter by the rotary positioning device to change the irradiation direction of the pulse laser, continuing the fan surface at the original position by the signal receiving end of the lateral signal receiving device to receive the ultrasonic signal generated by the new irradiation direction, transmitting the data to an external computer, generating a scanning image of the new direction by the computer according to the ultrasonic signal, and splicing the scanning image until an omnibearing two-dimensional image is obtained;
a6, the lateral signal receiving device is driven by the electric control translation stage to move to a new position on the Z axis, the fan-shaped receiving is carried out on the ultrasonic scanning signals generated under the multidirectional irradiation on the XY axis plane, the computer generates and splices a new omnibearing two-dimensional scanning image according to all ultrasonic signals received by the signal receiving end of the lateral signal receiving device at the new position, and then the combined processing is carried out on the ultrasonic scanning signals and the two-dimensional image data obtained in the step A5 to generate the three-dimensional imaging of the XYZ axis of the tissue to be scanned.
The ultrasonic signals received by the transducer are subjected to amplitude limiting, shaping, filtering and amplifying by an ultrasonic pulse receiver and then sent to a digital oscilloscope 13, and the digital oscilloscope 13 carries out multiple average processing on the ultrasonic signals and then sends the processed data to a computer through a GPIB card.
The distance between the output end of the optical fiber 12 and the reflecting mirror 11 is 5mm, and the output end of the optical fiber 12 and the reflecting mirror 11 are fixed by an adhesive.
The pulse laser source is an OPO pulse laser capable of outputting continuous adjustable pulse laser with 680-1000nm wave band or independently outputting 532nm or 1064nm wave band pulse laser, the pulse width is 6-8ns, the single pulse energy is about 4mJ, and the repetition frequency is 10Hz, and the pulse laser inputs laser to the optical fiber through the optical coupler.
The optical fiber is an end-fire multimode optical fiber with a numerical aperture of 0.25 and a diameter of 1.5 mm.
In this example, when the human prostate scanning photoacoustic imaging is performed, the movement of the signal receiving terminal on the Z axis is represented as the advancing and retreating movement of the signal receiving terminal at the human rectum.
In the embodiment, pulse laser is taken as a synchronous trigger signal to trigger a data acquisition computer to work so as to realize acquisition and recording of photoacoustic signals.
In this example, since the prostate is small (the transverse diameter of the upper end is about 4cm, the vertical diameter is about 3cm, and the anterior-posterior diameter is about 2 cm), the lateral irradiation range of the lateral signal excitation source is relatively large (2-3 cm), and the whole tissue can be covered only by the lateral irradiation in four directions. The signal receiving device connected with the rotating shaft of the rotating stepping motor can completely receive the ultrasonic scanning signal related to the whole gland by only driving the rotating stepping motor to perform small-angle fan-shaped scanning around the shaft in the rectum space for four times.
Commonly used adult urinary catheters are of the four types 12F, 14F, 16F, 18F with an outer diameter of 4-6mm. The catheter outer diameter is in the range of commonly used catheter outer diameters.
When testing the device, the simulated tissue can be used for simulating human prostate, and the preparation method is that the simulated sample substrate is formed by pouring agar powder (2 g), distilled water (100 ml) and fat emulsion (20 ml) into a columnar glassware to be coagulated by heating (concentration 20%), wherein the size is 4.5 x 5cm, a 6mm through hole is reserved in the middle for simulating urethra, and a carbon rod is used for simulating tumor.
Claims (6)
1. A side-scanning photoacoustic imaging apparatus for a prostate, characterized in that: the lateral scanning photoacoustic imaging device comprises a lateral signal excitation source and a lateral signal receiving device, wherein the lateral signal excitation source comprises an optical fiber, a reflecting mirror, a catheter and a pulse laser light source; the catheter is a detection catheter which can be inserted into a part to be detected; the tail end of the catheter is a light emitting end capable of laterally transmitting light, and a reflecting mirror which is arranged at an oblique angle with the catheter is arranged at the tail end of the light emitting end; the initial end of the conduit is connected with the rotary positioning device; an optical fiber is arranged in the catheter lumen, and the input end of the optical fiber is connected with a pulse laser light source; the optical fiber output end is positioned at the light emitting end and adjacent to the reflector, the tip of the optical fiber output end is polished to be vertical to the optical fiber body, and the light emitting direction of the optical fiber output end points to the reflector; the lateral signal receiving device is a lateral water immersion type long focal zone focusing ultrasonic receiving device; when the lateral scanning photoacoustic imaging device works, the rotary positioning device rotates the guide tube to enable the reflecting mirror to face the tissue to be scanned, and the pulse laser source emits pulse laser to the tissue to be scanned through the optical fiber and the reflecting mirror to enable the tissue to be scanned to generate a photoinduced ultrasonic signal; the direction of the reflecting mirror which is arranged at an oblique angle with the guide pipe is changed according to the requirement; the signal receiving device receives signals generated under the irradiation of all directions in a sector scanning mode and sends the signals to an external computer, and the computer generates unidirectional or spliced all-directional two-dimensional images of an XY plane according to the signals; the signal receiving end of the lateral signal receiving device is arranged on the translation stage, and when the signal receiving end moves on the Z axis to change the receiving position of the signal receiving end, an external computer processes the signals of the new and old receiving positions to realize three-dimensional photoacoustic imaging on the XYZ axis of the scanning target;
the lateral signal receiving device is a lateral water immersion type long focal zone focusing ultrasonic transducer;
the translation stage is an electric control translation stage, the electric control translation stage is provided with a rotary stepping motor, the signal receiving end of the lateral signal receiving device is connected with the rotary stepping motor, the rotary stepping motor changes the receiving direction of the signal receiving end, and the electric control translation stage is provided with the signal receiving end to move on the Z axis;
the working method for performing lateral scanning photoacoustic imaging on the human prostate by the lateral scanning photoacoustic imaging device sequentially comprises the following steps of;
a1, inserting a catheter into a prostate part of a human body through a catheter or directly inserting the catheter into the prostate part of the human body through a urethra, enabling a light emitting end of the catheter to be positioned beside a tissue to be scanned, and inserting a signal receiving end of a lateral signal receiving device into a rectum of the human body to perform an extraglandular noninvasive ultrasonic receiving operation;
a2, rotating the catheter by the rotary positioning device to enable the light emitting direction of the reflector to face to tissues to be scanned beside the light emitting end of the catheter;
a3, the pulse laser source emits pulse laser to the tissue to be scanned through the optical fiber and the reflecting mirror, so that the tissue to be scanned generates a photoinduced ultrasonic signal;
a4, the signal receiving end receives ultrasonic signals, and meanwhile, the lateral signal receiving device changes the direction of the signal receiving end under a static state so as to realize a signal receiving surface of a sector track, the signal receiving device transmits received ultrasonic signal data to an external computer, and the computer generates a single-direction scanning image according to the ultrasonic signals;
a5, rotating the catheter by the rotary positioning device to change the irradiation direction of the pulse laser, continuing the fan surface at the original position by the signal receiving end of the lateral signal receiving device to receive the ultrasonic signal generated by the new irradiation direction, transmitting the data to an external computer, generating a scanning image of the new direction by the computer according to the ultrasonic signal, and splicing the scanning image until an omnibearing two-dimensional image is obtained;
a6, the lateral signal receiving device is driven by the electric control translation stage to move to a new position on the Z axis, the fan-shaped receiving is carried out on the ultrasonic scanning signals generated under the multidirectional irradiation on the XY axis plane, a computer generates and splices a new omnibearing two-dimensional scanning image according to all ultrasonic signals received by the signal receiving end of the lateral signal receiving device at the new position, and then the new omnibearing two-dimensional scanning image is combined with the two-dimensional image data acquired in the step A5 to generate the three-dimensional imaging of the XYZ axis of the tissue to be scanned;
the ultrasonic signals collected by the focusing ultrasonic transducer are mainly derived from the area where the focus is located, the characteristics of good response to the photoacoustic signals in the focus area and almost zero response to the photoacoustic signals outside the focus area are achieved, when the photoacoustic imaging is performed through lateral scanning, the tissue body is scanned point by point through the focus area of the ultrasonic transducer, and longitudinal photoacoustic signals at a plurality of positions are combined to obtain a two-dimensional light absorption diagram of the tissue body;
when receiving ultrasonic scanning signals related to the whole prostate gland, the lateral signal excitation source covers the whole tissue by lateral irradiation in four directions, and the signal receiving device connected with the rotating shaft of the rotating stepping motor is driven by the rotating stepping motor to perform small-angle fan-shaped scanning around the shaft in the rectum space for four times to completely receive the signals.
2. A laterally scanning photoacoustic imaging apparatus for a prostate according to claim 1, wherein: the optical fiber is an end-emitting multimode optical fiber, and a reflecting mirror which is arranged at an angle of 45 degrees with the catheter is arranged at the tip of the light emitting end.
3. A side-scan photoacoustic imaging apparatus for a prostate according to claim 2, wherein: the outer diameter range of the catheter is the same as that of a common medical catheter.
4. A laterally scanning photoacoustic imaging apparatus for a prostate according to claim 1, wherein: the ultrasonic signals received by the transducer are subjected to amplitude limiting, shaping, filtering and amplifying by the ultrasonic pulse receiver and then sent to the digital oscilloscope, and the digital oscilloscope carries out multiple average processing on the ultrasonic signals and then sends the processed data to the computer through the GPIB card.
5. A laterally scanning photoacoustic imaging apparatus for a prostate according to claim 1, wherein: the distance between the optical fiber output end and the reflecting mirror is 5mm, and the optical fiber output end and the reflecting mirror are fixed by an adhesive.
6. A laterally scanning photoacoustic imaging apparatus for a prostate according to claim 1, wherein: the pulse laser source is an OPO pulse laser capable of outputting continuous adjustable pulse laser with 680-1000nm wave band or independently outputting 532nm or 1064nm wave band pulse laser, the pulse width is 6-8ns, the single pulse energy is about 4mJ, and the repetition frequency is 10Hz, and the pulse laser inputs laser to the optical fiber through the optical coupler.
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