JPWO2019103057A1 - Abnormal tissue detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormal tissue detecting device capable of highly accurately detecting an abnormal tissue at an inspection site. An abnormal tissue detecting apparatus compares each of a plurality of received signals IS_n with a reference signal SS generated by weighting and adding each of the plurality of received signals IS_n by a weighting factor, thereby obtaining an abnormal tissue. The component of the reflected wave from is detected. Here, the weighting coefficient for each of the plurality of reception signals IS_n is a component of a direct wave from the transmission antenna to the reception antenna between each of the plurality of reception signals IS_n and the reference signal SS, as compared with the case where the weighting is made uniform. Is determined so that the sum of the differences in the signal strength in the section including is small. [Selection diagram] Fig. 6

Description

The present invention relates to an abnormal tissue detecting device.

Conventionally, by radiating a microwave to the examination site of the subject and processing the received signal of the microwave detected by the receiving antenna, the component of the reflected wave from the abnormal tissue in the examination site is extracted, and the examination is performed. An abnormal tissue detection device that estimates the distribution of abnormal tissue in a site has been proposed (for example, Patent Document 1).

JP, 2014-131199, A

It is an object of the present invention to provide an abnormal tissue detecting device that can detect abnormal tissue at an inspection site with high accuracy.

An abnormal tissue detection apparatus according to an embodiment, a plurality of transmission antennas for transmitting microwaves toward the examination site of the subject, and any one of the plurality of transmission antennas transmits, direct wave from the transmission antenna. And a plurality of receiving antennas that receive microwaves including a component of a reflected wave from the abnormal tissue of the inspection site, the transmitting antenna and the receiving antenna have the same distance, and the transmitting antenna, the receiving antenna, and the inspection Reference signal generating means for generating a reference signal by synthesizing a plurality of signals received by the receiving antenna in a state where the relative positional relationship with the abnormal tissue of the part is different, and each of the plurality of signals and the reference signal generating means. By comparing with the reference signal to be generated, having an estimating means for estimating the component of the reflected wave from the abnormal tissue of the examination site contained in each of the plurality of signals, the reference signal generating means, The reference signal is generated by synthesizing the plurality of signals, and the weighting coefficient is compared with a case where the weighting is made uniform, a section including a direct wave component of each of the plurality of signals and the reference signal. It is characterized in that it is determined so that the sum of the differences in the signal intensities in 1 is reduced.

Here, "identical" does not only mean that they are exactly the same, but also that they are substantially the same. For example, in an abnormal tissue detection device having a plurality of transmitting antennas and receiving antennas, when receiving a plurality of signals while changing the combination of the transmitting antennas and the receiving antennas, the transmission error may occur due to the mounting error of the transmitting antennas and the receiving antennas. It is conceivable that the distance between the antenna and the receiving antenna may be slightly different for each combination, and such a case is also included in the “same” range.

According to the abnormal tissue detecting device of the present invention, it is possible to detect the abnormal tissue at the inspection site with high accuracy.

(A) is a perspective view showing an appearance of an abnormal tissue detecting device according to an embodiment, and (B) is an exploded perspective view showing a configuration of an abnormal tissue detecting device according to an embodiment. (A) is a side view showing the configuration of the antenna array, and (B) is a top view showing the configuration of the antenna array. It is a block diagram which shows the structure of an abnormal tissue detection apparatus. It is a graph which shows an example of the impulse signal output from a transmission part. (A) is a schematic diagram showing a transmitting/receiving antenna and a breast at the time of detecting abnormal tissue, (B) is a schematic diagram showing a principle of detecting abnormal tissue, and (C) is a schematic diagram showing a received signal. is there. It is a flow chart of abnormal tissue detection processing. It is a conceptual diagram which shows the removal method of the noise signal using averaging. It is a conceptual diagram which shows the calculation method of the reference signal using a weight. (A) is a graph showing an example of a differential signal when a reference signal is calculated using Tikhonov regularization, and (B) is an example of a differential signal when a reference signal is calculated using averaging. It is a graph shown. (A) is a figure which shows an example of the differential signal for 1 rotation when Tikhonov regularization is applied to 60 received signals, (B) is 60 received signals, and Tikhonov regularization is carried out. It is a figure which shows the example of the difference signal for 1 rotation when not applying. 6 is a graph showing an example of weights calculated using a Wiener filter to which Tikhonov regularization is applied and weights calculated using a Wiener filter to which Tikhonov regularization is not applied. (A) is a figure which shows the example of a confocal image when Tikhonov regularization is applied to 60 received signals, (B) is a case where Tikhonov regularization is not applied to 60 received signals. It is a figure which shows the example of the confocal image of. (A) is a figure which shows the example of the difference signal for 1 rotation when Tikhonov regularization is applied to 40 received signals, (B) is 40 received signals, and Tikhonov regularization is carried out. It is a figure which shows the example of the difference signal for 1 rotation when not applying. (A) is a figure which shows the example of a confocal image when Tikhonov regularization is applied to 40 received signals, (B) is a case where Tikhonov regularization is not applied to 40 received signals. It is a figure which shows the example of the confocal image of. It is a perspective view showing a modification of an abnormal tissue detecting device.

Hereinafter, an abnormal tissue detection device according to an embodiment of the present invention will be described in detail with reference to the drawings, using an abnormal tissue detection device for detecting breast cancer as an example.

As shown in FIGS. 1(A) and 1(B), the abnormal tissue detecting apparatus 1 according to the present embodiment includes a rotating unit 9 including a housing 57 and an antenna unit 3, a fixed base 31, and a drive unit. 33 and a handle 51.

A drive unit 33 for rotating the rotating unit 9 is fixed to the fixed base 31. The drive unit 33 is, for example, a stepping motor. The rotating part of the drive part 33 is fixed to the lid 52. As a result, the abnormal tissue detection device 1 rotatably supports the rotating unit 9 including the lid 52, the housing 57, the antenna unit 3, and the like. A handle 51 is attached to the upper part of the fixed base 31. An examiner holds the handle 51 and brings the rotating unit 9 into contact with the breast, which is the examination site of the subject, to perform the examination.

The rotating unit 9 includes a lid 52, a control board 55, a high frequency board 56, a housing 57, an antenna unit 3, an antenna cover 41, and a sleeve 42.

The antenna section 3 includes an antenna base 37, an antenna mounting section 39, and an antenna array 38. The antenna base 37 is a mounting member for fixing the antenna mounting portion 39 to the housing 57.

An antenna array 38 including antennas for transmitting and receiving microwave radio signals is attached to the antenna attachment portion 39. The antenna mounting portion 39 is fixed to the antenna base 37. The antenna mounting portion 39 is made of resin, for example, and the central portion is formed in a dome shape.

The antenna array 38 is composed of transmitting antennas SA1 to SA8 and receiving antennas RA1 to RA8. Each of the antennas forming the antenna array 38 is attached to the lower surface of the antenna attachment portion 39, that is, the surface of the antenna cover 41 that faces the dome-shaped portion. Further, wiring and the like for connecting each antenna and the switch unit 2 described later are arranged on the upper surface side of the antenna mounting portion 39 (inside the housing 57). As shown in FIGS. 2A and 2B, the transmitting antennas SA1 to SA8 and the receiving antennas RA1 to RA8 are arranged linearly in the radial direction from the center of the antenna mounting portion 39, and four antenna rows A1 are provided. A to A4 form an antenna array 38.

The antenna cover 41 is arranged so as to cover the outer surface of the antenna mounting portion 39 and contacts the body of the subject. The antenna cover 41 is screwed and fixed to the housing 57 via the sleeve 42. The central portion of the antenna cover 41 is formed in a dome shape that is concentric with the antenna mounting portion 39, and has a shape that makes it easy to make close contact with the breast that is the examination site. Further, a plurality of antenna mounting portions 39 and antenna covers 41 having different sizes may be prepared in advance so that one suitable for the size of the breast of the subject can be selected.

A space between the antenna mounting portion 39 and the antenna cover 41 is filled with a dielectric material having a dielectric constant close to that of the body of the subject and the antenna cover 41, such as petrolatum or anhydrous glycerin. As a result, it is possible to suppress the generation of unnecessary radiation between the antenna mounting portion 39 and the antenna cover 41, so that it is possible to improve the detection accuracy of abnormal tissue.

The control board 55 is a printed wiring board on which hardware circuits for realizing the functions of the control unit 14, the storage unit 15, and the drive control unit 34 shown in the block diagram of FIG. 3 are mounted, and is fixed in the housing 57. ing.

The drive control unit 34 is a motor driver that controls the rotation of the stepping motor that is the drive unit 33. As shown in FIG. 3, the drive control unit 34 rotates the drive unit 33 in accordance with a control signal from the control unit 14 to rotate the antenna unit 3 including the antenna array 38.

The control unit 14 is a part of the signal processing unit, and is a computer (information processing device) including a CPU, a memory, an external storage device, an input/output I/O, a crystal oscillator, and the like. According to the clock signal generated by the crystal oscillator, the CPU executes the program installed in the external storage device and read into the memory, and writes/reads data to/from the external storage device or external device via input/output I/O. The function of the control unit 14 is realized by performing transmission and reception with.

The storage unit 15 is a part of the signal processing unit, and is a nonvolatile memory such as a flash memory or a hard disk. As illustrated in FIG. 3, the control unit 14 transmits the reception signal RS received from the reception unit 12 to the storage unit 15 and stores the reception signal RS. The control unit 14 also reads the received signal RS stored in the storage unit 15 and performs signal processing such as calculation of the reference signal SS and extraction of a target signal by calculation of the difference signal DS_n.

As shown in FIG. 3, the control unit 14 outputs a timing signal indicating the timing of outputting the transmission signal TS to the transmission unit 11 and a control signal CS1 of the CMOS switch 17 by executing the program. The control unit 14 outputs the control signal CS2 of the CMOS switch 19 and inputs the waveform data of the reception signal RS from the reception unit 12.

The high frequency board 56 is a printed wiring board on which a hardware circuit that realizes the functions of the transmitter 11, the receiver 12, and the switch 2 shown in the block diagram of FIG. 3 is mounted, and is fixed in the housing 57. There is.

The transmission unit 11 is a hardware circuit that outputs, for example, a transmission signal TS that is an impulse-shaped electric signal shown in FIG. 4 according to a timing signal input from the control unit 14. As shown in FIG. 4, the level of this electric signal is an impulse signal that changes from a positive value to a negative value in a short time.

The switch unit 2 includes a CMOS switch 17 that selects a transmission antenna that transmits a microwave impulse signal among the transmission antennas SA1 to SA8, and a reception antenna that receives a scattered signal reflected by an abnormal tissue among the reception antennas RA1 to RA8. And a CMOS switch 19 for selecting.

The CMOS switch 17 inputs the transmission signal TS from the input end. The CMOS switch 17 switches the antenna that outputs the input transmission signal TS to one of the plurality of transmission antennas SA1, SA2,..., SA8 according to the control signal CS1.

The reception unit 12 is a hardware circuit that outputs the reception signal RS input from the CMOS switch 19 to the control unit 14. That is, it is an input unit for inputting the reception signal RS as the reception signal IS_n to the control unit 14 which is a signal processing unit. The control unit 14 performs signal processing based on the input received signal IS_n to detect the abnormal tissue CA.

As shown in the example of FIG. 3, when the transmission antenna SA2 is selected by the control signal CS1, the CMOS switch 17 switches to output the transmission signal TS to the transmission antenna SA2. When the receiving antenna RA2 is selected by the control signal CS2, the CMOS switch 19 switches to output the receiving signal RS received by the receiving antenna RA2 to the receiving unit 12. In this case, the transmission antenna SA2 and the reception antenna RA2 are combined to transmit the microwave impulse signal MW and receive the reflection signal RW. The signal output from the transmitting antenna SA2 is preferably an impulse signal in the sense that it contains more frequency components, but even a sine wave consisting of a single frequency component is a slope waveform containing multiple frequency components. Is also good.

The control unit 14 controls the CMOS switches 17 and 19 with the control signals CS1 and CS2 to output the transmission signal TS to the CMOS switch 17 while switching the combination of the transmission antennas SA1 to SA8 and the reception antennas RA1 to RA8. In addition, the control unit 14 operates as a signal processing unit that inputs the reception signal RS output from the reception antennas RA1 to RA8 via the CMOS switch 19 and performs signal processing on the input electric signal.

Next, the basic operation of the abnormal tissue detection device 1 for detecting abnormal tissue using a wireless signal will be described. The abnormal tissue detection device 1 according to the present embodiment transmits and receives an impulse-shaped microwave radio signal, and detects an abnormal tissue, that is, breast cancer, based on the transmission and reception result.

As shown in FIGS. 5A and 5B, in the abnormal tissue detecting device 1, the rotation angle θ of the rotating unit 9, that is, the antenna unit 3 including the transmitting antenna SA1 and the receiving antenna RA1 is set as an initial angle θ1 (angle1). , A microwave impulse signal MW is radiated from the transmitting antenna SA1. It is generally known that an abnormal tissue CA such as a cancer tissue has a dielectric constant that is about 5 to 10 times higher than that of a normal living tissue. Therefore, when the abnormal tissue CA exists, the microwave is reflected by the interface of the regions having different dielectric constants, that is, the surface of the abnormal tissue CA, and is received by the receiving antenna RA1 (hereinafter, referred to as a reflected wave).

Here, when the time from radiating the microwave impulse signal MW to receiving the reflected wave by the receiving antenna RA1 is T1 [s], T1·c (c: speed of light in living body) is It is the stroke distance of the wave impulse signal MW.

Therefore, the abnormal tissue CA is located on the ellipse E1 with the transmission antenna SA1 and the reception antenna RA1 as the focal points at the rotation angle θ1 and the sum of the distances from the transmission antenna SA1 and the reception antenna RA1 is T1·c. ..

Subsequently, the drive control unit 34 rotates the rotating unit 9 including the transmitting antenna SA1 and the receiving antenna RA1, and sets the rotation angle θ to θ2 (angle2). Then, the abnormal tissue detection device 1 radiates the microwave impulse signal MW from the transmission antenna SA1 and receives it by the reception antenna RA1. If the time from the radiation of the microwave impulse signal MW to the reception of the reflected wave by the receiving antenna RA1 is T2 [s], then T2·c is the stroke distance of the microwave impulse signal MW.

Therefore, the abnormal tissue CA is located on the ellipse E2 having the transmitting antenna SA1 and the receiving antenna RA1 as the focal points and the sum of the distances from the transmitting antenna SA1 and the receiving antenna RA1 being T2·c at the rotation angle θ2. ..

The same process is performed while sequentially rotating the transmitting antenna SA1 and the receiving antenna RA1, and the position of the abnormal tissue CA is determined by obtaining the intersections of a plurality of ellipses E1 to EN (N is a natural number, E3 and below are not shown). You can ask.

Further, the antenna transmitting the impulse signal MW is switched to the transmitting antenna SA2, the transmitting antenna SA2 radiates a microwave, the receiving antenna RA2 receives the microwave, and the same processing is performed. After that, the microwaves are radiated while the transmission antennas are sequentially switched, the reflected waves are received by the reception antennas, and the same processing is performed, whereby the position of the abnormal tissue CA can be specified more accurately.

In the above example, the description is made in two dimensions for easy understanding, but in reality, the above processing is performed in three dimensions.

However, in reality, the signal received by the receiving antenna RA1 includes a component other than the reflected wave component. That is, the signal received by the receiving antenna RA1 includes a direct wave component and a quantum noise component. Here, the direct wave is a wave in which the microwave radiated from the transmitting antenna SA1 propagates through the closest path and reaches the receiving antenna RA1 regardless of the presence or absence of the abnormal tissue CA. Therefore, the signal actually received by the receiving antenna RA1 includes the component of the combined wave of the direct wave and the reflected wave when the abnormal tissue CA exists, and only the component of the direct wave when the abnormal tissue CA does not exist. Will be included.

The direct wave has a higher signal strength and a shorter propagation time than the reflected wave. It is necessary to accurately estimate the propagation time of the reflected wave by suppressing the direct wave component and other noise signal components from the composite wave or emphasizing the reflected wave component by utilizing this difference in properties. There is.

In this respect, if the distance between the transmitting antenna SA1 and the receiving antenna RA1 is constant, the component of the direct wave is constant but the component of the reflected wave is constant even if the rotation angle θ and the combination of the transmitting antenna and the receiving antenna are different. Varies depending on the relative positional relationship between these antennas and the abnormal tissue CA. Therefore, by simply averaging the received signals measured in a positional relationship in which the distance between the transmitting antenna and the receiving antenna is the same and the relative positions of the antenna and the abnormal tissue CA are different, each received signal is calculated. Since the components of the quantum noise and the component of the reflected wave that are different signal components are canceled out and become relatively small, the component of the direct wave that is a component common to each received signal is emphasized and becomes relatively large, The wave component can be estimated (hereinafter referred to as a reference signal). Then, by subtracting the reference signal, which is the estimated direct wave, from each received signal, it is possible to generate a signal in which the reflected wave is relatively emphasized.

However, as a result of the verification, even if the relative distance between the transmitting antenna and the receiving antenna is constant, the component of the direct wave is not always constant when the rotation angle θ or the combination of the transmitting antenna and the receiving antenna is different. confirmed. For example, since the transmitting antenna and the receiving antenna cannot be configured by ideal point light sources and point observation sources, the direct wave path has a certain cross-sectional area. The presence or absence of reflection on the surface of the abnormal tissue CA differs depending on whether the abnormal tissue CA exists in the path of the direct wave or not. When the microwave is reflected on the surface of the abnormal tissue CA, energy is lost by the reflected amount, so that the intensity of the direct wave becomes relatively weaker than that when the microwave is not reflected. In addition, due to various causes such as mechanical error such as mounting error and rotation error of transmitting antenna and receiving antenna, difference in shape of examination site and difference in tissue distribution inside examination site, direct wave intensity and propagation velocity are different. The difference in the intensity and propagation velocity of the direct wave due to these causes brings about a slight difference in the component of the direct wave in each received signal. Then, when these received signals are simply averaged, a reference signal in which the component of the direct wave is distorted is obtained. Therefore, when such a reference signal is subtracted from each received signal, the direct wave component is not subtracted as ideal, and the distortion component remains. Even if the residual distortion component is weaker than the direct wave component, the intensity of the reflected wave component is weaker than the direct wave component, so the reflected wave component is There is a possibility of accidentally specifying it.

Therefore, in the present embodiment, the reference signal is acquired by performing weighted addition on each received signal. Here, the weighting coefficient used for weighting addition is such that the total difference in signal strength between the reference signal and each received signal in the section including the component of the direct wave is smaller than that in the case where the weighting is made uniform. Is decided. In other words, the signal value of the acquired reference signal is determined so as to match the signal value of the direct wave component of each received signal more closely. In the present embodiment, as an example, a method of determining a weighting coefficient by a Wiener filter to which Tikhonov regularization is applied will be described.

Hereinafter, for the sake of simplicity of explanation, as shown in FIG. 7, the section including the component of the direct wave in the received signal IS_n is referred to as a first section, and the section including the component of the reflected wave is referred to as a second section. The control unit 14 first sets the first section and the second section for the received signal IS_n. Here, various methods can be applied to the setting of the first section. For example, since the distance between the transmitting antenna SA1 and the receiving antenna RA1, the strength of the impulse signal radiated from the transmitting antenna SA1 and the approximate attenuation coefficient of the examination site are known, the transmitting antenna SA1 radiates the impulse signal. From, it is possible to calculate an approximate time width until the direct wave reaching the reception antenna RA1 is attenuated, and this time width may be set as the first section in the reception signal IS_n. In addition, by radiating an impulse signal from the transmitting antenna SA1 and receiving a signal by the receiving antenna RA1 with respect to a phantom simulating an examination site in advance, the transmitting antenna SA1 radiates the impulse signal and then the receiving antenna. A method is conceivable in which the time width until the direct wave reaching RA1 is attenuated is acquired and stored in the storage unit 15. In this case, when the radiation of the impulse signal from the transmission antenna SA1 and the reception of the signal by the reception antenna RA1 are actually performed on the examination site of the subject, the time width stored in the storage unit 15 is called, and It can be set as a section. Then, the time width after the first section is set as the second section.

Next, as shown in FIG. 8, the control unit 14 controls the sampling value Si(t) (i=1 to n, t=1 to L, L>n, n, L) of the first section of the reception signal IS_n. Is a natural number) and is multiplied by a weighting factor wi to add Sdesired(1) to Sdesired(L). Here, L is the number of samples in the first section of each received signal, and n is a value corresponding to the maximum value of the rotation angle of the antenna unit 3, and for example, 360° while rotating the antenna unit 3 by 6°. When the received signal is acquired over, n=60 (=360/6). Then, the weight coefficient w corresponding to each received signal IS_n is determined so that the difference between Sdesired(t) and Si(t) is minimized.

Hereinafter, a method of determining the weight coefficient w by the Wiener filter to which the Tikhonov regularization is applied based on the signal of the first section of each received signal IS_n will be described in more detail. Specifically, the weighting coefficient w that satisfies the following equation (1) is determined.

Here, b is a reference signal vector, H is a received signal matrix, and w is a weighting coefficient vector. Here, each element in the weighting coefficient vector w is a weighting coefficient w by which each received signal IS_n is multiplied when the reference signal SS is generated. Further, λ is a regularization parameter, and is arbitrarily set within the range of λ>0. By introducing the second term of Expression (1) including λ, it is possible to prevent the norm of each element of the weighting coefficient vector w from becoming excessive. However, if λ is set excessively, each element of the weighting coefficient vector w converges to 1/n, so that the same result as in the case where the received signal IS_n is simply averaged to generate the reference signal SS is obtained. Therefore, while preventing the norm of each element of the weighting coefficient vector w from becoming excessive, it is possible to obtain a reference signal having a signal value that more closely matches the signal value of the component of the direct wave of each received signal IS_n. It is desirable to set λ.

Subsequently, a specific solution of the equation (1) will be described. Expression (1) can be transformed into Expression (5) by introducing variables x and y shown in the following expressions.

Further, the least squares solution of the equation (5) is given by the following equation (6).

Therefore, the weighting factor to be obtained is given by the following equation (7).

The control unit 14 multiplies the signal of the first section and the signal of the second section of the corresponding received signal IS_n by the weighting factor w calculated by the above method, and adds the weighted coefficient w to generate the reference signal SS. .. Further, the control unit 14 subtracts the reference signal SS from each reception signal IS_n to calculate the difference signal DS_n. Here, since the signal value of the reference signal SS is generated so as to match the signal value of the component of the direct wave of each reception signal IS_n, the intensity of the component of the direct wave included in the difference signal DS_n. Is much smaller than the intensity of the reflected wave component. Therefore, for example, by setting an appropriate threshold value for the signal strength, the reflected wave component in the differential signal DS_n can be accurately extracted.

In the setting of the first section for the received signal IS_n, the weighting coefficient w of the weighted addition is calculated so that the generated reference signal SS matches the direct wave component of each received signal IS_n more closely. , It is desirable to set a section including the component of the direct wave but not the component of the reflected wave as the first section for the received signal IS_n. However, in the present invention, the first section is set so that at least the set first section includes a part of the component of the direct wave and the outside of the first section includes a part of the component of the reflected wave. It should be done. If the first section is set under such a condition, compared to the reference signal SS obtained by integrating the received signals IS_n in a uniform weighting state, the received signal IS_n is more matched to the direct wave component. The weighting factor w can be determined to obtain the reference signal SS that

Further, in the above embodiment, the weighting coefficient is determined by the Wiener filter to which Tikhonov regularization is applied, but in the present invention, the weighting is applied to the reference signal SS obtained by integrating the received signals IS_n in a uniform state. In comparison, various calculations can be applied as long as the weighting factor w is determined so as to obtain the reference signal SS that is more consistent with the direct wave component of each received signal IS_n.

Next, an abnormal tissue detection process in the abnormal tissue detection device 1 according to the present embodiment, that is, a signal process using the reference signal SS will be described based on the flowchart shown in FIG.

The control unit 14 sets the rotation angle θ of the rotating unit 9 including the antenna unit 3 to the initial rotation angle (θ=0°) (step S11). Then, the transmission signal SA is transmitted from the transmission antenna SA1, and the reception signal RS is received by the reception antenna RA1 (step S12). The control unit 14 stores the reception signal RS received by the reception antenna RA1 in the storage unit 15 as the reception signal IS_1 (step S13).

Since the rotation angle of the rotation unit 9 is θ=0° and θ<360° (step S14; NO), the control unit 14 operates the drive unit 33 to rotate the rotation unit 9 by a preset angle rotation. (Step S15). In the present embodiment, the preset angle is 6°, and the rotating unit 9 makes one rotation in 60 rotation operations. After the rotation of the rotating unit 9 is completed, the process returns to step S12, and the control unit 14 causes the transmission antenna SA1 to transmit the transmission signal TS and the reception antenna RA1 to receive the reception signal RS. The control unit 14 stores the reception signal RS as the reception signal IS_2 in the storage unit 15.

The control unit 14 further rotates the rotating unit 9 to transmit/receive a signal between the transmitting antenna SA1 and the receiving antenna RA1. The control unit 14 repeats the above-described rotation operation and signal transmission/reception until the rotation angle θ reaches 360°, and stores 60 reception signals IS_n (n=1 to 60) in the storage unit 15.

When the rotation angle θ reaches 360° and the reception of the reception signal IS_n is completed (step S14; YES), the signal processing of the input reception signal IS_n is started. The control unit 14 reads the reception signal IS_n from the storage unit 15 (step S16).

The control unit 14 sets the first section and the second section for the received signal IS_n, and based on the signal of the first section of each received signal IS_n, the weighting coefficient is applied by the Wiener filter to which Tikhonov regularization is applied. w is determined (step S17). Then, the reference signal SS is generated by multiplying the determined weight coefficient w by the signal of the first section and the signal of the second section in the corresponding received signal IS_n and adding them (step S18). The control unit 14 further subtracts the reference signal SS from each reception signal IS_n to calculate the difference signal DS_n (step S19). Then, the component of the reflected wave in the differential signal DS_n is extracted, the position of the abnormal tissue CA at the inspection site is detected based on the extracted component of the reflected wave (step S20), and the signal processing ends.

An example of the result of the above signal processing is shown in FIGS. 9(A) and 9(B). FIG. 9A shows the received signal IS_n when the rotation angle of the rotating unit 9 is 126°, the reference signal SS calculated by the method of the present invention, and the difference signal DS_n obtained by subtracting the reference signal SS from the received signal IS_n. There is. In addition, FIG. 9B illustrates a received signal IS_n, a reference signal SS when the received signals IS_n are integrated in a uniform weighting state to form a reference signal SS, and a difference signal DS_n obtained by subtracting the reference signal SS from the received signal IS_n. Is shown. From this, it can be seen that the direct wave component in the differential signal DS_n is suppressed sufficiently smaller than the reflected wave component by applying the method of the present invention.

FIG. 10A shows a result of one rotation in which the differential signal DS_n is calculated at each position where the rotation angle of the rotating unit 9 is from 0° to 360°. FIG. 10B shows the difference signal DS_n by using the weighting factor w determined by applying the Wiener filter that does not apply the Tikhonov regularization shown in the following Expression (8) to the first section of the received signal IS_n. The result for one rotation when calculated is shown.

In the signal processing method of the present invention to which the Tikhonov regularization shown in FIG. 10(A) is applied, the noise in the second section is reduced as compared with the case where the Tikhonov regularization shown in FIG. 10(B) is not used. I understand. This is because, as shown in FIG. 11, the weighting coefficient w when the Tikhonov regularization is performed is suppressed to be smaller than the weighting coefficient w when the Tikhonov regularization is not performed.

12A and 12B show the results of FIGS. 10A and 10B described above as confocal images. The SCR (Signal to Clutter Ratio) in the case of Tikhonov regularization shown in FIG. 12(A) is 5.025 dB, which is larger than the SCR=0.69 dB in the case of not performing Tikhonov regularization shown in FIG. 12(B). , The S/N ratio is increasing.

FIG. 13A shows a differential signal DS_n calculated using Tikhonov regularization when n=40, that is, when the rotating unit 9 is rotated in 9° steps to create the received signal IS_n. Further, FIG. 13B shows the differential signal DS_n calculated by using the Wiener filter that creates the received signal IS_n with n=40 and does not apply the Tikhonov regularization. 14A and 14B show confocal images based on the difference signal DS_n when n=40.

From the results shown in FIGS. 13(A), (B) and FIGS. 14(A), (B), when the Wiener filter to which the Tikhonov regularization according to the present invention is applied is used, as compared with the case where the Tikhonov regularization is not performed. Thus, it can be seen that the S/N ratio is large and the target signal can be clearly detected. Therefore, it is understood that the signal processing method according to the present invention can effectively reduce the noise signal even when the number of received signals IS_n is small.

As described above in detail, according to the present embodiment, since the weighting factor w is calculated by the Wiener filter to which Tikhonov regularization is applied, it is possible to prevent the norm of the weighting factor w from becoming excessive. .. This makes it possible to appropriately remove the noise signal, improve the S/N ratio of the differential signal, and clearly extract the target signal.

As described above, various embodiments and modifications of the present invention are possible without departing from the broad spirit and scope of the present invention. Further, the above-described embodiments are for explaining the present invention, and do not limit the scope of the present invention. That is, the scope of the present invention is shown not by the embodiments but by the scope of the claims. Various modifications made within the scope of the claims and the scope of the invention equivalent thereto are considered to be within the scope of the present invention.

In the present embodiment, while maintaining the relative positional relationship between the transmitting antenna SA1 and the receiving antenna RA1, these antennas are rotated around the inspection site, and a plurality of received signals IS_n are acquired in the meantime. Not limited to In the present invention, it is only necessary to acquire a plurality of signals in the state where the distance between the transmitting antenna and the receiving antenna is the same and the relative positional relationship between the transmitting antenna and the receiving antenna and the abnormal tissue in the examination region is different. For example, in an abnormal tissue detection apparatus including an antenna array in which a plurality of antennas are arranged, a plurality of combinations are determined so that the distances between the antennas are the same, and in each combination, one antenna is directed to the examination site. The microwave may be radiated by the other antenna, and the other antenna may receive the signal including the reflected wave from the abnormal tissue at the examination site.

Further, although the input unit according to the present embodiment is the receiving unit 12, the input unit is not limited to this. For example, it may be an external storage device such as a hard disk or a flash memory that stores the reception signal IS_n acquired in advance.

Further, in the present embodiment, the antenna cover 41 is fixed to the housing 57 and is rotated together with the antenna mounting portion 39, but the present invention is not limited to this. For example, as shown in FIG. 15, the antenna cover 41 may be connected to the fixed plate 44 attached between the fixed base 31 and the handle 51 via the sleeve 42. Thereby, even if the antenna mounting portion 39 fixed to the antenna base 37 rotates, the antenna cover 41 connected to the fixed plate 44 does not rotate. Therefore, during the inspection, the antenna cover 41 that is in contact with the subject does not rotate, and the physical burden on the subject during the inspection can be reduced.

Abnormal tissue detection apparatus according to the present embodiment, a plurality of transmission antennas for transmitting microwaves toward the examination site of the subject, and any one of the plurality of transmission antennas, direct from the transmission antenna. A plurality of receiving antennas for receiving microwaves including a component of a wave and a component of a reflected wave from the abnormal tissue of the inspection site, the transmitting antenna and the receiving antenna have the same distance, and the transmitting antenna and the receiving antenna Reference signal generating means for generating a reference signal by synthesizing a plurality of signals received by the receiving antenna in a state where the relative positional relationship with the abnormal tissue of the inspection site is different, and each of the plurality of signals and the reference signal generating means. By comparing with the reference signal generated by, by estimating means for estimating the component of the reflected wave from the abnormal tissue of the examination site contained in each of the plurality of signals, the reference signal generating means, , The reference signal is generated by synthesizing the plurality of signals, and a weighting coefficient includes a direct wave component of each of the plurality of signals and the reference signal, as compared with the case where the weighting is made uniform. It is characterized in that the determination is made so that the sum of the differences in the signal strength in the section becomes small.

The above-mentioned abnormal tissue detection device is determined so that the sum of the signal strength differences between the plurality of signals and the reference signal in the section including the component of the direct wave becomes smaller than that in the case where the weighting is made uniform. A reference signal is generated using a weighting factor that compares the reference signal with a plurality of signals, so that the component of the reflected wave from the abnormal tissue included in each of the plurality of signals is accurately extracted, and the Abnormal tissue can be detected with high accuracy.

Further, the abnormal tissue detection apparatus includes rotation control means for rotating the transmission antenna and the reception antenna around the inspection region while maintaining the relative positions, and the reference signal generation means is configured to transmit the rotation control means to transmit the reference signal. While rotating the antenna and the receiving antenna, the receiving antenna may generate a reference signal based on a plurality of signals received at different rotation angles. Thereby, the rotation control means accurately extracts the component of the reflected wave from the abnormal tissue included in each of the plurality of signals acquired while rotating the transmitting antenna and the receiving antenna around the examination site, Abnormal tissue can be detected with high accuracy.

Further, the reference signal generation means is configured such that the rotation control means, based on the plurality of signals received by the reception antenna while the pair of transmission antennas and reception antennas rotate around the inspection region, the reference signal. May be generated. As a result, the component of the reflected wave from the abnormal tissue contained in each of the plurality of signals acquired while the pair of the transmitting antenna and the receiving antenna rotates around the examination site is accurately extracted, and the abnormal tissue of the examination site is extracted. Can be detected with high accuracy.

In addition, each of the plurality of signals has a first section including a component of a direct wave and a second section including a component of a reflected wave, and the reference signal generating unit includes each of the plurality of signals. By determining the weighting factor based on the signal of the first section in the above, and performing weighted addition on the signal of the first section and the signal of the second section in each of the plurality of signals. A reference signal may be generated. In this case, by determining the weighting coefficient based on the signal in the first section, when comparing each of the plurality of signals with the reference signal, the component of the direct wave in each of the plurality of signals is the component of the reflected wave. A weighting coefficient that is smaller than As a result, the component of the reflected wave from the abnormal tissue included in each of the plurality of signals can be more accurately extracted, and the abnormal tissue at the inspection site can be detected with high accuracy.

Further, the reference signal generation means may determine the weighting coefficient by a Wiener filter to which Tikhonov regularization is applied, based on the signal in the first section in each of the plurality of signals. In this case, the application of Tikhonov regularization can prevent the norm of the determined weighting factors from becoming excessive and improve the S/N ratio of the signal obtained by comparing each of the plurality of signals with the reference signal. be able to.

Further, the inspection site may be a breast, and the abnormal tissue may be cancer contained in the breast. Thereby, the breast cancer contained in the breast can be detected based on the extracted reflected wave component.

The present invention is suitable for an antenna device used for a breast cancer sensor or the like. Further, the present invention is not limited to a breast cancer sensor, and can be applied to detection/discrimination of other regions such as tumors having different dielectric constants in a living body. Further, it can be applied to the detection/discrimination of a detection target having a different dielectric constant from the surroundings regardless of the living body.

1 Abnormal Tissue Detecting Device, 2 Switch Part, 3 Antenna Part, 9 Rotating Part, 11 Transmitting Part, 12 Receiving Part, 14 Control Part, 15 Storage Part, 17, 19 CMOS Switch, 31 Fixed Base, 33 Driving Part, 34 Drive control section, 37 antenna base, 38 antenna array, 39 antenna mounting section, 41 antenna cover, 42 sleeve, 44 fixing plate, 51 handle, 52 lid, 55 control board, 56 high frequency board, 57 housing, SA1 to SA8 transmission Antenna, RA1 to RA8 reception antenna, A1 to A4 antenna array, CA abnormal tissue, L inductor, E ₁ , E ₂ ellipse, SS reference signal, TS transmission signal, RS reception signal, MW impulse signal, RW reflection signal, CS1, CS2 control signal

Claims (6)

A plurality of transmitting antennas for transmitting microwaves toward the examination site of the subject;
A plurality of receiving antennas that transmit any one of the plurality of transmitting antennas and receive microwaves that include a component of a direct wave from the transmitting antenna and a component of a reflected wave from the abnormal tissue of the inspection site,
A reference signal obtained by synthesizing a plurality of signals received by the receiving antenna in a state in which the transmitting antenna and the receiving antenna have the same distance and the relative positional relationship between the transmitting antenna and the receiving antenna and the abnormal tissue in the examination region is different. A reference signal generating means for generating
Estimating to estimate the component of the reflected wave from the abnormal tissue of the examination site included in each of the plurality of signals by comparing each of the plurality of signals with the reference signal generated by the reference signal generating means And means,
The reference signal generation means generates the reference signal by combining the plurality of signals, and a weighting coefficient, as compared with a case where the weighting is made uniform, each of the plurality of signals and the reference signal, An abnormal tissue detecting device, characterized in that it is determined so that a total of signal intensity differences in a section including a component of a direct wave becomes small. The abnormal tissue detecting device according to claim 1,
A rotation control means for rotating the periphery of the inspection site while maintaining the relative positions of the transmission antenna and the reception antenna,
The reference signal generation means may generate a reference signal based on a plurality of signals received by the reception antenna at different rotation angles while the rotation control means rotates the transmission antenna and the reception antenna. A device for detecting abnormal tissue, which is characterized. The reference signal generation unit generates the reference signal based on the plurality of signals received by the reception antenna while the rotation control unit rotates a pair of the transmission antenna and the reception antenna around the inspection region. The abnormal tissue detecting device according to claim 2, wherein Each of the plurality of signals has a first section including a component of a direct wave and a second section including a component of a reflected wave,
The reference signal generation means determines the weighting factor based on a signal of the first section in each of the plurality of signals,
The reference signal is generated by performing weighted addition on the signal in the first section and the signal in the second section in each of the plurality of signals. The abnormal tissue detection device according to one item. The said reference signal production|generation means determines the said weighting coefficient by the Wiener filter to which Tikhonov regularization was applied based on the signal of the said 1st area in each of the said several signal. Abnormal tissue detection device. The examination site is a breast,
The abnormal tissue detecting apparatus according to claim 1, wherein the abnormal tissue is a cancer contained in the breast.

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