Circuit networks for photoacoustic-ultrasonic probes and photoacoustic-ultrasonic probes having them

Abstract

This invention relates to a circuit network for a photoacoustic-ultrasound probe and a photoacoustic-ultrasound probe having the same. It proposes a new circuit network that solves the problem of voltage level imbalance between photoacoustic and ultrasonic signals when acquiring data using optically-resolved integrated photoacoustic-ultrasound endoscopes, mini-probes, or catheter devices based on a single-element transducer and mechanical scanning method in the prior art. It also addresses the concept of effectively triggering a data acquisition device, i.e., a digitizer, even in the absence of missing relevant data.

Description

Technical Field

[0001] This utility model relates to a medical tomographic endoscope device, which is embodied in the form of a slender probe, similar to that of an ultrasound endoscope currently used in the clinical field, and is capable of being inserted into the body to provide tomographic images of the surrounding area. Background Technology

[0002] This invention relates to the so-called integrated photoacoustic and ultrasonic endoscopy (PAE-EUS) technology. PAE-EUS is a technology that provides photoacoustic imaging information while maintaining the functionality of existing endoscopic ultrasound. Utility Model Content

[0003] Technical issues

[0004] In existing technologies, it is impossible to solve the signal imbalance problem that may occur when using a single digitizer to simultaneously acquire photoacoustic and ultrasonic signals.

[0005] Technical solution

[0006] This invention presents a method in which, through an original circuit configuration comprising an ultrasonic transceiver switch, an RF switch, and a variable amplifier to amplify photoacoustic and ultrasonic signals with independent gain values, the dynamic ranges of the two signals can be matched to a similar degree after amplification. Furthermore, in the process of acquiring the respective A-line signals of photoacoustic and ultrasonic signals at each step of the scanning tip, by applying a single trigger pulse input to the digitizer instead of the existing dual-pulse input, the trigger rate of the digitizer can be reduced to half that of the prior art.

[0007] Beneficial effects

[0008] When using the independent amplification circuit network for photoacoustic and ultrasonic signals proposed in this invention, the problem of one of the amplified photoacoustic or ultrasonic A-line signals exceeding the dynamic range of the digitizer or data loss due to excessive input of the digitizer trigger frequency will not occur. Thus, the required photoacoustic-ultrasonic dual-mode image sequence can be implemented more quickly and stably. Attached Figure Description

[0009] Figure 1 A simulation diagram illustrating the overall concept of a signal amplification circuit is provided, which can be applied to a photoacoustic-ultrasonic probe device according to an embodiment of the present invention.

[0010] Figure 2 Showing according to Figure 1 The concept shown is an embodiment of a related circuit network.

[0011] Figure 3a and 3b The following are the trigger sequences for the digitizer, which can be used to start it. Figure 2 One embodiment is shown.

[0012] Best mode

[0013] This invention allows for various modifications and can have various embodiments; therefore, specific embodiments are shown in the accompanying drawings and described in detail. The effects and specific methods of achieving these effects and specific methods will become apparent from the embodiments described in detail with reference to the accompanying drawings. However, this invention is not limited to the embodiments disclosed below and can be embodied in various forms.

[0014] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. When describing the invention with reference to the accompanying drawings, the same or corresponding constituent elements will be referred to by the same reference numerals and will not be described again.

[0015] In the following embodiments, the terms "first," "second," etc., are not limiting in meaning, but are used to distinguish one constituent element from other constituent elements.

[0016] In the following embodiments, unless it is obvious from the context that the singular form includes the plural form.

[0017] In the following embodiments, terms such as “comprising” or “having” refer to the presence of features or constituent elements described in the specification, and do not preclude the possibility of adding one or more other features or constituent elements.

[0018] In the following embodiments, if a constituent element is "connected" to other constituent elements, this includes not only the case where the constituent element is directly connected to other constituent elements, but also the case where it is indirectly connected through another constituent element.

[0019] Figure 1 A simulation diagram illustrating the concept of a signal amplification circuit, which is derived according to this invention and can be widely applied to various photoacoustic-ultrasonic probe devices.

[0020] Reference Figure 1 The ultrasonic transducer excitation and signal amplification circuit network derived from this invention includes a pulse generator 100, an ultrasonic transceiver (T / R) switch 300, a first radio frequency (RF) switch 400, an ultrasonic signal variable amplifier 500, a photoacoustic signal variable amplifier 600, and a second radio frequency (RF) switch 700. The elements mentioned above are used by being connected to a load called an ultrasonic transducer 200; therefore, as... Figure 1 As shown, the ultrasonic transducer 200 can be arranged between the pulse generator 100 and the ultrasonic transceiver switch 300, and the digitizer 800 for data acquisition can be connected to the terminal of the circuit network. In other words, the circuit network including the pulse generator 100 and the ultrasonic transducer 200, as well as the other components mentioned above, can be the circuit network for a photoacoustic-ultrasonic probe according to the present invention. Furthermore, the configuration including this circuit network for a photoacoustic-ultrasonic probe, the pulse generator 100, and the ultrasonic transducer 200 can be considered as the photoacoustic-ultrasonic probe according to the present invention.

[0021] Continue to refer to Figure 1 Describe the relevant operational concepts. Each step pulse generated at the scanning tip (not shown) of the photoacoustic-ultrasonic probe enters as a "pulse generator trigger pulse". Figure 1 The pulse generator 100 shown transmits a very short, high-voltage electrical pulse to an ultrasonic transducer 200 connected to the output of the pulse generator 100. In response to the electrical pulse, the ultrasonic transducer 200, after emitting an ultrasonic wave, detects its reflected wave and transmits the electrical signal to an ultrasonic transceiver switch 300, which serves as the next terminal.

[0022] Obviously, even without the aforementioned "pulse generator trigger pulse," the photoacoustic signal detected by the ultrasonic transducer 200 after the pulsed laser (not shown) emits a laser pulse towards the object under test is also transmitted to the ultrasonic transceiver switch 300. However, since electrical pulses and laser pulses are emitted at different times, the ultrasonic transceiver switch 300 appropriately switches its electrical signal receiving mode to a high impedance mode and a low impedance mode accordingly. In other words, the ultrasonic transceiver switch 300 can switch to a high impedance mode when receiving ultrasonic-related electrical signals and to a low impedance mode when receiving laser pulse-related photoacoustic signals. When alternately receiving ultrasonic-related electrical signals and laser pulse-related photoacoustic signals, the ultrasonic transceiver switch 300 can repeatedly select between the high impedance mode and the low impedance mode.

[0023] Furthermore, the first RF switch appropriately transmits the ultrasonic signal and photoacoustic signal received from the ultrasonic transceiver switch 300 to the ultrasonic signal variable amplifier 500 and the photoacoustic signal variable amplifier 600, respectively, based on the timing of the electrical pulse and laser pulse emission. In other words, the first RF switch 400 transmits the ultrasonic-related signal received from the ultrasonic transceiver switch 300 to the ultrasonic variable amplifier 500, and the photoacoustic-related signal received from the ultrasonic transceiver switch 300 to the photoacoustic variable amplifier 600. Each variable amplifier that has received these signals amplifies each signal according to a pre-set amplification gain value. The amplification gain value set for each variable amplifier is set such that the amplified photoacoustic signal and ultrasonic signal have similar voltage levels. In other words, the voltage level of the ultrasonic-related signal amplified by the ultrasonic variable amplifier 500 can correspond to the voltage level of the photoacoustic-related signal amplified by the photoacoustic variable amplifier 600. The electrical signals amplified to a certain level by each variable amplifier are transmitted to the second RF switch 700 and combined, and then jointly acquired by the subsequently connected digitizer 800.

[0024] It is worth noting that the ultrasonic transceiver switch 300, the first radio frequency switch 400, or the second radio frequency switch 700 used in the utility model concept proposed in this specification are merely exemplary names, and these components can be replaced by devices with other forms or names that perform the above-described functions. Furthermore, when ultrasonic signals and photoacoustic signals exhibit a wide dynamic range depending on the type and distance of the sound source, a non-linear amplifier such as a logarithmic amplifier can be used instead of a linear amplifier.

[0025] and, Figure 1 Only the most basic elements required to realize the core concept derived from this invention are shown. A low-noise preamplifier (not shown) capable of defending against high-voltage pulses can be attached between the ultrasonic transducer 200 and the ultrasonic transceiver switch 300. According to another embodiment, by attaching the low-noise preamplifier between the ultrasonic transceiver switch 300 and the first RF switch 400 to minimize noise interference, weak photoacoustic signals and initial ultrasonic signals can be amplified in an earlier step. Examples of low-noise preamplifiers capable of defending against high-voltage pulses include the MAX4805 from Maxin Integrated. The ultrasonic transceiver switch 300, the first RF switch 400, or the second RF switch 700 are common in the relevant fields, so specific models are omitted. Obviously, the above-described combination according to this invention is not known, and no inspiration for such a combination exists. Furthermore, it is possible to... Figure 1 The signal processing steps formed by the various elements shown are supplemented with filters or capacitors, etc.

[0026] Figure 1 Only one embodiment is shown. Therefore, if the A-line data lengths of the photoacoustic signal and the ultrasonic signal to be acquired are significantly different, and the number of A-line data sets to be acquired differs with each rotation of the scanning tip, two or more digitizers can be connected independently to acquire the signals differently, instead of as... Figure 1 The diagram shows the use of a single digitizer. In this case, since the photoacoustic and ultrasonic signals are individually acquired and recorded by two independent digitizers, the number of A-line data sets to be acquired for each rotation of the scanning tip can be easily set to different values. Therefore, the number of pulses triggering each digitizer per unit time can also be appropriately and differently set. Obviously, an additional second RF switch 700 is not required in this case. The second RF switch 700 is used to combine the photoacoustic and ultrasonic signals into a single port and transmit it to its backend. Detailed Implementation

[0027] Figure 2 Showing according to Figure 1 The illustrated concept is further embodied in an embodiment of a related circuit network. The operating principle of this circuit is the same as described above. Figure 1 The operating principle is the same, so it will not be described again. The only difference is that a rotary transformer 900 is added before entering the ultrasonic transducer 200. Furthermore, this embodiment shows the use of a first radio frequency switch 400 and a second radio frequency switch 700, each with its own driver, i.e., drive circuit. It is worth noting that the hollow arrows shown along the wires indicate the path of the signal movement detected by the ultrasonic transducer 200, and the symbols +V, -V, VP, and VN respectively indicate the drive voltage that needs to be supplied to the relevant elements.

[0028] Figure 3a and Figure 3b The trigger sequence of the digitizer is shown below, which can be applied to startup. Figure 2 One embodiment is shown. Based on this, a novel digitizer trigger sequence proposed by this invention will be presented.

[0029] first, Figure 3a This invention illustrates a triggering method that is identical to the triggering method used in existing digitizers for integrated optical-photoacoustic-ultrasound endoscopes, probes, miniature probes, catheters, etc., based on a single transducer and mechanical scanning method, and can also be applied to the devices described in this invention. Figures 1 to 2 The circuitry is as follows. As described above, each step signal at the scanning tip generates both a photoacoustic signal and an ultrasonic trigger signal to trigger the digitizer 800. As a result, the digitizer 800 is triggered at a frequency approximately twice the step frequency of the scanning tip. The T in the attached diagram represents a parameter indicating the period.

[0030] Figure 3b The diagram illustrates that, according to the present invention, only one trigger pulse is generated for each step signal at the scanning tip to trigger the sequence of the digitizer 800. In other words, one trigger pulse is used for each step signal, so the same waveform as the step signal waveform at the scanning tip can be directly input into the digitizer 800 without the need for a trigger waveform with low duty (<<50%) as shown in the accompanying figure.

[0031] However, it is noteworthy that the triggering time of the digitizer 800 needs to be consistent with or synchronized with the emission time of the laser pulse emitted in each step, and the synchronization with the laser pulse emission time should include the process of emitting ultrasonic pulses at a time earlier than the predetermined time, as in... Figure 3a The above shows the independent digitizer triggering time points used for recording ultrasonic signals. In other words, only the signal to be recorded for the ultrasonic signal is not transmitted to the digitizer; the process of emitting laser pulses and ultrasonic pulses needs to remain constant, such as... Figure 3a As shown.

[0032] Even with this sequence, the reason why photoacoustic and ultrasonic signals can be successfully acquired and recorded is that, typically for optical resolution photoacoustic mode, the relevant signal has a very short duration from the surface of the object to a depth of 1 mm or less and disappears immediately. In other words, this is because the photoacoustic signal in optical resolution mode is a more transient signal compared to the co-registered ultrasonic signal. Therefore, as Figure 3a and Figure 3b The core concept is that each step signal at the scanning tip provides only one trigger pulse to the digitizer 800, resulting in the acquisition of ultrasound signals followed by photoacoustic signals in a group of A-line signal columns.

[0033] In optical-resolution integrated photoacoustic-ultrasound endoscopes, probes, miniature probes, or catheters based on a single-element transducer and mechanical scanning method, the photoacoustic and ultrasonic signals, which have significantly different signal levels before amplification (i.e., just transmitted from the ultrasonic transducer), are amplified using only a commercially available pulse generator / receiver (e.g., Olympus 5072PR). Since both signals are amplified with the same gain value and then acquired using a digitizer (i.e., a data acquisition device), there is a problem of signal saturation to the set dynamic range of the digitizer or higher, resulting in signal loss.

[0034] Furthermore, during the acquisition of each A-column signal, since only the method of alternately transmitting trigger pulses corresponding to the acquisition of photoacoustic and ultrasonic signals to the digitizer is implemented, there is a possibility that the frequency of triggering the digitizer may be twice the step frequency of the corresponding endoscope mechanical scanning tip, i.e., the digitizer trigger frequency is excessively increased.

[0035] For example, assuming the endoscope's scanning tip rotates in 800 steps per second and performs 30 rotational scans per second, the step frequency is the product of these two, i.e., 24 kHz. The trigger frequency of the digitizer used to alternately obtain photoacoustic and ultrasonic A-line signals based on the existing circuitry mentioned above is further increased to twice 24 kHz, i.e., 48 kHz. While the increased digitizer trigger frequency does not often cause problems, if the step frequency is further increased and the data length of each A-line signal increases, the digitizer may malfunction, leading to data loss.

[0036] The purpose of transmitting two trigger pulses to the digitizer at each step of the scanning tip is to distinguish between photoacoustic signals and ultrasonic signals through each trigger pulse. According to the method of this invention as described above, only one trigger pulse signal is sufficient to distinguish the two signals.

[0037] The reason for reducing the number of time-dependent trigger pulses of the input digitizer is that, typically, each time a trigger pulse is input, the digitizer needs a certain amount of time to sense and respond to the trigger pulse. As a result, it is impossible to acquire any continuously input electrical signals within the response time.

[0038] Although the invention has primarily described a circuit network for a photoacoustic-ultrasonic probe, it is not limited thereto. For example, circuit networks comprising elements other than the pulse generator and ultrasonic transducer described above, and photoacoustic-ultrasonic probes comprising a pulse generator and an ultrasonic transducer, may also be considered to fall within the scope of this invention.

[0039] The above presents a method to address the potential signal imbalance problem when simultaneously acquiring photoacoustic and ultrasonic signals using a single digitizer, and a new trigger sequence that more effectively triggers the digitizer without data loss during implementation. To the best of my knowledge, in the field of optical-photoacoustic-ultrasound integrated endoscopes based on a single transducer and mechanical scanning method, no identical technical solution has been proposed, nor have any related problems been addressed.

[0040] As described above, the concept of using devices such as RF switches to separate two different signals input through a single sensor and amplifying and processing the separated signals with different gains should be extended to situations where the types of signals to be processed are three or more, or where various signals input through multiple sensors need to be converged to a single port for acquisition and recording.

[0041] Industrial applicability

[0042] The circuit network for photoacoustic-ultrasound probes proposed in this invention can be used in photoacoustic-ultrasound probes and applied to medical computed tomography endoscopes.

Claims

1. A circuit network for a photoacoustic-ultrasound probe, characterized in that include: An ultrasonic transceiver (T / R) switch that can receive signals from an ultrasonic transducer; A variable ultrasonic signal amplifier, which can amplify received ultrasonic-related signals; A photoacoustic signal variable amplifier, which can amplify the received photoacoustic related signals; as well as A first radio frequency (RF) switch receives signals from the ultrasonic transceiver (T / R) switch and transmits the signals to the ultrasonic signal variable amplifier and the photoacoustic signal variable amplifier.

2. The circuit network for a photoacoustic-ultrasound probe according to claim 1, characterized in that It further includes a second radio frequency (RF) switch that receives signals from the ultrasonic signal variable amplifier and the photoacoustic signal variable amplifier.

3. The circuit network for a photoacoustic-ultrasonic probe according to claim 1, characterized in that, The first radio frequency (RF) switch transmits the ultrasonic correlation signal received from the ultrasonic transceiver (T / R) switch to the ultrasonic signal variable amplifier, and transmits the photoacoustic correlation signal received from the ultrasonic transceiver (T / R) switch to the photoacoustic signal variable amplifier.

4. The circuit network for a photoacoustic-ultrasonic probe according to claim 1, characterized in that, The ultrasonic transceiver (T / R) switch receives signals while switching between high-impedance and low-impedance modes.

5. The circuit network for a photoacoustic-ultrasonic probe according to claim 4, characterized in that, The ultrasonic transceiver (T / R) switch alternately switches between high impedance mode and low impedance mode.

6. The circuit network for a photoacoustic-ultrasonic probe according to claim 1, characterized in that, The voltage level of the ultrasound-related signal amplified by the ultrasound signal variable amplifier corresponds to the voltage level of the photoacoustic-related signal amplified by the photoacoustic signal variable amplifier.

7. The circuit network for a photoacoustic-ultrasound probe according to claim 1, characterized in that It further includes a digitizer that receives and acquires signals from the second radio frequency (RF) switch.

8. A photoacoustic-ultrasonic probe, characterized in that... include: Circuit network for photoacoustic-ultrasonic probe according to any one of claims 1 to 7; A pulse generator that generates high-voltage electrical pulses; and an ultrasonic transducer that receives the electrical pulses from the pulse generator, emits ultrasound, and then detects the reflected waves.

9. The photoacoustic-ultrasonic probe according to claim 8, characterized in that, The ultrasonic transducer also detects photoacoustic signals, which are generated by the reflection of the emitted laser pulse from the object under test.

10. The photoacoustic-ultrasonic probe according to claim 8, characterized in that... It further includes a low-noise preamplifier located between the ultrasonic transducer and the ultrasonic transceiver (T / R) switch.

11. The photoacoustic-ultrasonic probe according to claim 8, characterized in that... It further includes a low-noise preamplifier located between the ultrasonic transceiver (T / R) switch and the first radio frequency (RF) switch.

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