WO2025069233A1 - Energy transmission device and medical system - Google Patents

Abstract

Provided are an energy transmission device and a medical system that make it possible to more accurately estimate the energy of a wave emitted from an energy emission unit. An energy transmission device (100) comprises: a wave source (110) capable of generating a wave at a predetermined frequency; a transmission path (120) for transmitting the wave; an energy emission unit (130) for emitting, to the surroundings, the wave transmitted via the transmission path; a frequency adjustment unit (140) capable of adjusting the frequency of the wave; an information acquisition unit (150) for acquiring reflected wave information pertaining to the amplitude and the phase of a composite wave obtained by combining a plurality of reflected waves generated due to reflection of the wave transmitted via the transmission path; and a computation unit (160) for computing the amplitude and the phase of the composite wave on the basis of the reflected wave information, and computing the magnitude of the energy of the wave emitted from the energy emission unit on the basis of the amplitude and the phase of the composite wave.

Description

Energy transmission device and medical system

The present invention relates to an energy transmission device and a medical system.

　In the past, devices that utilize waves with a specific frequency have been developed in various industrial fields. For example, the following Patent Document 1 proposes using microwaves as waves to impart energy to a specific treatment site within a living body.

In devices that utilize waves such as those described above, it is important to check and adjust the output energy from the energy radiating unit (e.g., antenna element) that emits energy. In particular, when radiating energy inside a living body, it is desirable for the difference between the set radiated energy and the energy that is actually radiated to be as small as possible, taking into account the effects on the living body, so it is necessary to control the energy radiated from the energy radiating unit more precisely.

JP 2022-091850 A

Waves generated by a wave source (e.g., a microwave oscillator) produce reflected waves at various points along the transmission path (e.g., coaxial cables and various electrical connectors) that connects the wave source to the energy radiator, and these reflected waves then interfere with each other to produce a composite wave.

The inventors of the present invention have discovered that by analyzing information about the amplitude and phase of the composite wave generated as described above, it is possible to more accurately estimate the energy of the waves radiated from the energy radiating portion.

The present invention aims to provide an energy transmission device and a medical system that can more accurately estimate the wave energy radiated from an energy radiating section.

The energy transmission device disclosed herein includes a wave source capable of generating waves of a predetermined frequency, a transmission path for transmitting the waves, an energy emission unit for emitting the waves transmitted via the transmission path to the surroundings, a frequency adjustment unit for adjusting the frequency of the waves, an information acquisition unit for acquiring reflected wave information related to the amplitude and phase of a composite wave formed by combining multiple reflected waves generated by reflecting the waves transmitted via the transmission path, and a calculation unit for calculating the amplitude and phase of the composite wave based on the reflected wave information, and for calculating the magnitude of energy of the waves radiated from the energy emission unit based on the amplitude and phase of the composite wave.

According to the present disclosure, it is possible to more accurately confirm the wave energy radiated from the energy radiating section.

FIG. 1 is a schematic diagram illustrating an energy delivery device and a medical system according to an embodiment.

Below, an embodiment of the present invention will be described with reference to the attached drawings. Note that the following description does not limit the technical scope or the meaning of the terms described in the claims. Also, the dimensional ratios in the drawings have been exaggerated for the convenience of explanation and may differ from the actual ratios. Also, the range "X to Y" shown in this specification means "greater than or equal to X and less than or equal to Y."

FIG. 1 is a schematic diagram illustrating an energy transmission device and a medical system according to an embodiment.

As shown in FIG. 1, the energy transmission device 100 has a wave source 110 capable of generating waves of a predetermined frequency, a transmission path 120 for transmitting the waves, an energy radiating unit 130 for emitting the waves transmitted via the transmission path 120 to the surroundings, a frequency adjusting unit 140 for adjusting the frequency of the waves, an information acquiring unit 150 for acquiring reflected wave information related to the amplitude and phase of a composite wave formed by combining multiple reflected waves generated by reflecting the waves transmitted via the transmission path 120, and a calculation unit 160 for calculating the amplitude and phase of the composite wave based on the reflected wave information, and for calculating the magnitude of the energy of the waves radiated from the energy radiating unit 130 based on the amplitude and phase of the composite wave.

In this embodiment, the energy transmission device 100 and the catheter 200 constitute a specific medical system 10.

The waves generated by the wave source 110 are not particularly limited as long as they have wave properties and a certain amount of energy. Examples of waves include electromagnetic waves including microwaves and sound waves. In this embodiment, an example is described in which microwaves generated by the wave source 110 are radiated from the energy radiating section 130.

The wave source 110 can be a known microwave source configured to generate a predetermined wave motion.

The transmission path 120 can be composed of various members capable of transmitting the waves generated by the wave source 110 to the energy radiating section 130. In this embodiment, the transmission path 120 is formed by a plurality of coaxial cables 121a, 121b, and 121b electrically connected to the wave source 110 and a plurality of connectors 122a and 122b.

The coaxial cable 121a is directly connected to the wave source 110. The coaxial cable 121b is connected to the coaxial cable 121a via the connector 122a. The coaxial cable 121c is connected to the coaxial cable 121c via the connector 121b. The coaxial cable 121 can be disposed inside the catheter 200, and the energy emitting unit 130 can be disposed near the tip of the catheter 200.

The catheter 200 can be configured, for example, as an ablation catheter that radiates energy emitted from the energy radiating unit 130 to a specific part of the body. When the catheter 200 is configured in this manner, the energy radiating unit 130 can be configured as an antenna element capable of radiating microwaves.

The frequency adjustment unit 140, the information acquisition unit 150, and the calculation unit 160 can be incorporated as part of the device configuration of the wave source 110.

The wave source 110 has a control unit (not shown) that controls all operations performed by the wave source 110 and all parts of the device. The control unit can be configured with a known microcomputer consisting of a CPU, RAM, ROM, etc. The CPU in the control unit reads various programs pre-stored in the ROM into the RAM and executes them, thereby executing the specified processing related to this embodiment. The control unit also has a memory unit that stores various setting information and control programs, a calculation unit 160 that performs various calculations, and a function as a judgment unit that judges the operating state of the energy emission unit 130 based on the results of the calculations by the calculation unit 160.

The information acquisition unit 150 has a power meter 151 that measures the amplitude of the composite wave and a phase detector 152 that measures the phase of the composite wave. In this embodiment, the information acquisition unit 150 is configured to include a voltmeter 153 that can measure the voltage of the composite wave in addition to the power meter 151 and the phase detector 152. The information acquisition unit 150 does not have to include the voltmeter 153.

The medical system 10 and energy transmission device 100 shown in Figure 1 can solve the problems described below.

As shown in FIG. 1, in a medical system 10 (ablation system) in which a wave source 110 (microwave source) and multiple coaxial cables 121a, 121b, and 121c are connected in series to transmit waves, and an energy radiating unit 130 (microwave antenna) is implemented on the tip side (tip side of the catheter 200), the waves (microwaves) transmitted from the wave source 110 travel to the energy radiating unit 130 while being attenuated in each of the coaxial cables 121a, 121b, and 121c.

Most of the energy of the wave source that reaches each connector 122a, 122b is transmitted through each connector 122a, 122b, while a small amount of energy is reflected by each connector 122a, 122b.

Most of the energy that reaches the energy radiating unit 130 without being reflected is radiated as microwaves into the space surrounding the energy radiating unit 130. However, a portion of the energy that reaches the energy radiating unit 130 is also reflected by the energy radiating unit 130.

When using microwave energy emitted from the tip of the medical system 10 of this embodiment (the energy emitting unit 130 located near the tip of the catheter 200) for ablation treatment, it is important to more accurately confirm the energy radiated from the energy emitting unit 130 for the following reasons.

For example, if the energy radiating unit 130 is manufactured as an antenna element, individual differences during manufacturing of the antenna element may cause variations in the actual energy emitted from the antenna element, or unexpected degradation of the antenna's performance may occur due to damage during transportation or use, which may result in a situation in which the energy radiated from the antenna element does not reach the specified part of the living body (the part to be treated). In order to quickly detect such a situation in a medical setting where the catheter 200 is used, it is necessary to accurately grasp the energy radiated from the energy radiating unit 130. However, the following points are problematic in accurately grasping the energy radiated from the energy radiating unit 130.

In general, the wave source 110 has a function for measuring the power of the waves (microwaves) that have been reflected to the wave source 110. Therefore, the medical system 10 can detect the increase or decrease in the power of the waves that have been reflected to the wave source 110 by using the above function provided by the wave source 110. Therefore, the energy transmission device 100 can also evaluate the deterioration of the antenna performance based on the increase or decrease in the power of the waves detected by the wave source 110.

For example, when evaluating performance using the above system, it is possible to set predetermined thresholds such as "when the energy emitting unit 130 is functioning normally, the energy reflected from the energy emitting unit 130 to the wave source 110 is about 3% of the incident energy (energy supplied from the wave source 110 to the coaxial cable 121a)," "when the energy emitting unit 130 is in a faulty state, the above value is about 20%," and "when the system is in a completely faulty state (for example, the coaxial cable is broken), the above value is 100%." Furthermore, when the thresholds are set in this way, the system can be configured to determine that "a state in which the reflected wave measured by the wave source 110 has increased to 20% or more of the incident energy is a fault." However, the reflected wave measured by the wave source 110 is attenuated in the coaxial cables 121a, 121b, and 121c while returning from the energy emitting unit 130 to the wave source 110. Therefore, the absolute value of the reflected wave energy detected by the wave source 110 is smaller than the actual value that should be measured by the energy emission unit 130 located at the tip of the system due to the effects of attenuation in the coaxial cables 121a, 121b, and 121c.

Furthermore, the energy of the reflected wave detected by wave source 110 is a composite wave of the reflected wave generated by each connector 122a, 122b (hereinafter referred to as the "connector side reflected wave") and the reflected wave generated by energy radiating section 130 (hereinafter referred to as the "antenna side reflected wave"). Although the connector side reflected wave is usually very small, since the reflection position is closer to wave source 110, the attenuation on the way to reaching wave source 110 is relatively small. Therefore, the connector side reflected wave has a relatively large contribution to the composite wave detected by wave source 110.

Furthermore, in the medical system 10 (treatment system) of this embodiment, the catheter 200 is inserted into a body cavity such as a blood vessel, and therefore the part that comes into contact with the patient must be provided as a disposable item from the viewpoint of preventing infection. For example, the part located on the tip side of the system (the side that is introduced into the patient's body) of the connector 122a is replaced with a different one for each patient. In other words, a different component part is used each time it is used for treatment or procedure for the tip side of the connector 122a. Therefore, the lengths of the coaxial cables 121b and 121c provided in the medical system 10 include variations due to tolerances. Therefore, among the reflected waves from the connector 121a, the reflected waves from the connector 121b, and the reflected waves from the energy emitting unit 130, the reflected waves from the connector 121b and the energy emitting unit 130 have random phase shifts due to the tolerances of the path lengths. Therefore, the amplitude of the composite wave measured by the wave source 110 varies greatly each time a different coaxial cable is connected.

As described above, the normal/failure state of the energy emitting unit 130 results in a difference in the reflected wave power measured by the wave source 110, but this difference becomes very small at the time it is detected by the wave source 110. Therefore, in the reflected wave power detected by the wave source 110, the reflected wave power from the energy emitting unit 130 becomes submerged in the variation due to the phase shift of the reflected waves from each connector 121a, 121b. For this reason, it can be said that it is extremely difficult to detect a failure state of the energy emitting unit 130 by setting a uniform cutoff value for the reflected wave power detected by the wave source 110.

Other possible solutions to the above problems include eliminating as rejects in advance antennas equipped with coaxial cables whose path length increases the amplitude of the composite wave, and measuring the characteristics of each antenna during manufacture, recording the results, and canceling the effects of phase shift. However, both of these methods reduce product yields and increase manufacturing costs, and even if they can detect a certain level of performance degradation, they cannot detect the amount of energy actually radiated from the energy radiating section.

In this embodiment, in response to the above-mentioned problems, it is possible to provide a system that can more accurately grasp (estimate) the energy of the waves (microwaves) radiated from the energy emission unit 130 through calculations (processing) by the calculation unit 160. This embodiment is useful in that it can detect changes in the energy of the waves radiated from the energy emission unit 130 and make decisions such as appropriately adjusting the magnitude of the energy output or, in some cases, making an emergency stop to the radiation of energy, without incurring a significant increase in cost.

To solve the above problems, specifically, the calculation unit 160 performs the following processing.

When the frequency of the waves is changed by the frequency adjustment unit 140, the calculation unit 160 uses the fact that the phase fluctuation of each reflected wave (the reflected wave generated in each part of the medical system 10) in response to the change in frequency depends on the wavelength and propagation distance in the transmission path to each reflection position where each reflected wave is generated (e.g., each connector 122a, 122b, the energy emitting unit 130, etc.) to calculate the magnitude of the energy radiated from the energy emitting unit 130.

In addition, instead of or in addition to the above process, when the frequency of the wave is changed by the frequency adjustment unit 140, the calculation unit 160 utilizes the fact that the speed of change in the phase of each reflected wave in response to a change in frequency depends on the wavelength and propagation distance in the transmission path to each reflection position where each reflected wave is generated, to separate the composite wave into individual reflected components, thereby calculating the magnitude of the energy radiated from the energy radiating unit 100. More specifically, the calculation unit 160 separates the composite wave into individual reflected components, calculates the propagation distance of each reflected component, and further identifies the reflected component from the energy radiating unit 130 based on the propagation distance to the reflection position, thereby calculating the magnitude of the energy radiated from the energy radiating unit 130.

Below, an example of a calculation method performed by the calculation unit 160 is described.

Let us consider the case where the reflection positions at connectors 122a, 122b, and energy radiator 130 (antenna element) are fixed (unmoving). The reflected waves of each voltage can be expressed in complex numbers, excluding the time-varying terms, as shown in the following equation.

In the above formula, A ₁ , A ₂ , and A ₃ are the amplitudes of the respective reflected waves, L ₁ , L ₂ , and L ₃ are the distances from the wave source 110 to the respective reflection positions, and λ is the wavelength.

Also, λ = c/f, and the wavelength is inversely proportional to the frequency (c is the speed of light in each of the coaxial cables 121a, 121b, and 121c, and f is the frequency).

Moreover, the observed signal p _all (λ) is p _all (λ)=p ₁ (λ)+p ₂ (λ)+p ₃ (λ).

When t = const. and x = 1/λ on the complex plane, each reflected component rotates with a different amplitude and rotation speed as x increases. In addition, the observation signal pall, which is the sum of these reflected components, rotates while tracing a complex trajectory on the complex plane.

If the microwave source of the wave source 110 is a solid-state type, the transmission frequency f can be swept within a certain range. In particular, the frequency range f = 2400 to 2500 MHz is an ISM frequency band, which is an advantageous frequency band from the viewpoint of electromagnetic compatibility.

If the propagation speed c within the coaxial cable is 3 x ¹⁰⁸ m/s, _L1 = 2.0 m, _L2 = 3.0 m, and _L3 = 3.7 m, when the frequency is changed from 2400 to 2500 MHz, the phases of _p1 , _p2 , and _p3 change to 480 deg, 720 deg, and 888 deg, respectively.

In other words, when the frequency is changed between 2400 and 2500 MHz, p ₁ , p ₂ , and p ₃ all generate a phase shift of at least one period on the complex plane, and therefore the observed P _all well reflects the characteristics of each component.

Since the function form is known, the individual signal components can be separated into p1, p2, _{and p3 by fitting each of the parameters A1, A2, A3, L1, L2, and L3 to the data on the amplitude and phase} fluctuations of _P all when the frequency is changed.

Since the magnitude of the incident wave and the attenuation in each of the coaxial cables 121a, 121b, and 121c are known, the power incident on the energy emitting unit 130 can be calculated. The calculation unit 160 can further estimate the actual energy emitted from the energy emitting unit 130 by calculating the difference between the power of the reflected wave component at the energy emitting unit 130 separated by the above procedure and the incident power.

Therefore, the energy transmission device 100 and medical system 10 can preset the desired amount of energy emitted from the energy emission unit 130, automatically increase or decrease the incident energy from the wave source 110 so that the energy emitted does not deviate from the set range, and if the range of deviation is large, can determine that a malfunction has occurred and perform an emergency stop of the waves (microwaves). As a result, this embodiment can provide a medical system 10 that is safer.

10 Medical system 100 Energy transmission device 110 Wave source 120 Transmission path 121a Coaxial cable 121b Coaxial cable 121c Coaxial cable 122a Connector 122b Connector 130 Energy emission unit 140 Frequency adjustment unit 150 Information acquisition unit 151 Power meter 152 Phase detector 153 Voltmeter 160 Calculation unit 200 Catheter

Claims (6)

A wave source capable of generating waves of a predetermined frequency;
A transmission path for transmitting the wave;
an energy emitting unit that emits the wave transmitted through the transmission line to the surroundings;
A frequency adjusting unit that adjusts the frequency of the wave;
an information acquiring unit that acquires reflected wave information regarding an amplitude and a phase of a composite wave obtained by combining a plurality of reflected waves generated by reflecting the wave motion transmitted through the transmission path;
a calculation unit that calculates the amplitude and phase of the composite wave based on the reflected wave information, and calculates the magnitude of the wave energy radiated from the energy radiating unit based on the amplitude and phase of the composite wave. The calculation unit is
2. The energy transmission device of claim 1, wherein when the frequency of the wave is changed by the frequency adjustment unit, the magnitude of the energy radiated from the energy radiating unit is calculated by utilizing the fact that the fluctuation in phase of each of the reflected waves in response to the change in frequency depends on the wavelength and propagation distance in the transmission path to each reflection point where each of the reflected waves is generated. The calculation unit is
3. The energy transmission device according to claim 1 or claim 2, wherein when the frequency of the wave is changed by the frequency adjustment unit, the speed of phase change of each of the reflected waves in response to the change in frequency depends on the wavelength and propagation distance in the transmission path to each reflection point where each of the reflected waves is generated, and by utilizing this, the magnitude of the energy radiated from the energy radiating unit is calculated by separating the composite wave into individual reflected components. The energy transmission device according to claim 3, wherein the calculation unit separates the composite wave into individual reflected components, calculates the propagation distance of each reflected component, and further identifies the reflected component from the energy emission unit based on the propagation distance to the reflection point, thereby calculating the magnitude of the energy emitted from the energy emission unit. The wave source has a microwave oscillation source capable of generating microwaves as the wave motion,
the energy emitting unit has an antenna element capable of emitting the microwave,
the transmission path includes a coaxial cable and a plurality of connectors that connect the microwave oscillation source and the energy emitting unit so as to be capable of transmitting the wave motion;
The energy transmission device according to claim 1 , wherein the information acquisition unit includes a power meter that measures the amplitude and a phase detector that measures the phase. An energy transmission device according to any one of claims 1 to 5;
A medical device comprising a catheter having the energy emitting portion disposed at a tip thereof.