JP5868458B2 - measuring device - Google Patents

Description

The present invention propagates within a measurement target such as an ultrasonic diagnostic apparatus that diagnoses cancer and the like by using a probe that transmits and receives ultrasonic waves, and a photoacoustic diagnostic apparatus that captures a diagnostic image using photoacoustics. The present invention relates to a measuring apparatus and a measuring method for receiving imaged acoustic waves and generating image data and the like. In this specification, an acoustic wave includes what is called a sound wave, an ultrasonic wave, and a photoacoustic wave. For example, an acoustic wave generated inside a measurement target by irradiating the measurement target with light (electromagnetic waves) such as near infrared rays. Or a reflected acoustic wave that is transmitted inside the measurement object and reflected inside the measurement object.

A measuring apparatus that diagnoses cancer or the like by using a probe is widely used in the medical field. In recent years, in order to apply a measuring device having a probe to screening screening such as group screening, reduction of operator dependency and reduction of inspection time are required. As a proposal for this, regarding the organ to be measured, by making the scanning density of the probe near the boundary line such as the contour high, and by making the scanning density of the probe in other regions low, A method for shortening the inspection time is disclosed (see Patent Document 1). However, in this method, the scanning area of the probe is the same for all subjects. For this reason, when the measurement object differs depending on the subject as in the case of screening diagnosis of breast cancer, the probe also scans a region where the measurement object does not exist, and the examination time may be redundant.

In some cases, a shape maintaining member such as a holding plate for fixing the measurement target is provided. In such a case, if the scanning area determined as the device is captured in full size while holding the measurement object by the shape maintaining member, the measurement operation is performed over the entire scanning area on the surface of the shape maintaining member regardless of the presence or absence of the measurement object. To complete, a uniform time is required for each diagnosis. At the same time, the subject is burdened more than necessary.

JP 2004-290249 A

In view of the above problems, the present invention provides an apparatus and method for performing measurement while holding a measurement target, and for determining the presence or absence of the measurement target based on the characteristics of the received signal, for example, a scanning mode of a probe. It is an object to make it possible to shorten the measurement time by adjusting the signal processing mode and the like.

In view of the above problems, a measurement apparatus according to the present invention includes a holding member that holds a measurement target, light irradiation means for irradiating the measurement target with light, a probe, and a reception circuit that processes a reception signal. And a storage unit for recording the received signal processed by the receiving circuit . The probe includes an electromechanical transducer for receiving a photoacoustic wave generated from the measurement object by being irradiated with light from the light irradiation means via the holding member and converting the received signal into a received signal. And configured to be scanned. The light irradiating means is configured such that an irradiation region to the measurement object moves in synchronization with the probe, and when the amplitude of the received signal does not substantially change , the scanning position of the probe there provided with determination means for determining that the region is not effective to measure the measurement target, and with the control is performed of the light irradiation unit based on a determination by the determining means, receiving at said receiver circuit Processing of the signal or recording of the received signal in the previous storage unit is omitted .

According to the present invention, it is possible to appropriately control the light irradiation means based on the determination that the measurement target held by the holding member is in an area that is not effective in measuring the scanning area of the probe.

The block diagram which shows the structure of 1st Embodiment of the measuring apparatus of this invention. The top view explaining the example of the scanning mode of a probe. The block diagram which shows the structure of 2nd Embodiment of the measuring apparatus of this invention.

A feature of the present invention is that the determination that the probe that receives the acoustic wave from the measurement object held by the holding member is in an area that is not effective for measuring the measurement object is determined based on the reception signal of the acoustic wave. The measurement mode is controlled based on the determination. Based on this concept, the measurement equipment of the present invention has a basic configuration such as described at the means for solving the above problems. More specific embodiments are possible as described below.

The electromechanical transducer provided in the probe only needs to receive at least an acoustic wave. When the electromechanical transducer has an acoustic wave transmission function and a reception function, the electromechanical transducer emits an acoustic wave to a measurement target such as a living body and receives a reflected wave of the acoustic wave from the measurement target. . When the electromechanical transducer has only an acoustic wave receiving function, the electromechanical transducer receives a photoacoustic wave generated from thermal expansion of the measurement target due to light irradiation from the light irradiation means to the measurement target. The probe may be manually moved along the surface of the shape maintaining member, but includes a probe moving means for scanning the probe along the surface of the shape maintaining member with respect to the measurement target. In this case, it becomes more convenient and easy to control the measurement mode based on the determination.

In the determination, for example, when it is determined that the amplitude of the received signal has not substantially changed for a predetermined time, it is determined that the probe is scanning the surface region of the shape maintaining member where the measurement target does not exist. Alternatively, the reference signal received when the probe is scanning the surface region of the shape maintaining member where the measurement target does not exist is measured and stored in advance. When the stored reference signal and the received signal substantially match, it can be determined that the probe is scanning the surface region of the shape maintaining member where the measurement target does not exist. When it is determined that the probe is scanning the surface region of the shape maintaining member where no measurement object exists, the measurement mode can be controlled as follows. For example, the scanning of the probe by the probe moving means is stopped, the scanning speed of the probe is changed, and the scanning direction of the probe is changed. It is also possible to stop the transmission function, the reception function, and the measurement light emission function of the light irradiation means of the electromechanical converter. It is also possible to start image display following the start of generation of image data using the received signal. Measurement time can be shortened by performing at least one of these controls. For example, if scanning of the probe is stopped and image display is started following the start of processing for generating image data using the received signals stored so far, unnecessary scanning can be avoided. Measurement time can be shortened. When scanning the probe manually, a stop instruction signal may be issued to prompt the operator to stop. At this time, it is possible to simultaneously stop the transmission function, the reception function, and the measurement light emission function of the light irradiation means. The probe scan speed change, scan direction change, etc. are performed when a reception signal indicating the absence of the measurement target is received for a relatively short time after the reception signal obtained by scanning the measurement target existing area. , Can be done. On the other hand, the scanning of the probe is stopped when a reception signal indicating the absence of the measurement object is received for a certain length of time after the reception signal is obtained by scanning the existence area of the measurement object. , Can be done. The somewhat long time is, for example, a time such that the corresponding scanning length is three times or more the length of the shape maintaining member. This is because it is preferable to stop the scanning of the probe after the absence of the measurement target is reliably confirmed. In the present invention, the electromechanical conversion device may be of any type (for example, a conversion device using piezoelectric ceramic, a capacitive CMUT, an MMUT using a magnetic film, a PMUT using a piezoelectric thin film, etc.). be able to.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
The block diagram of FIG. 1 shows the overall configuration of the first embodiment of the measuring apparatus of the present invention. As shown in FIG. 1, this measuring apparatus includes a probe 4, and the probe 4 has an ultrasonic transducer that is an electromechanical transducer that receives an acoustic wave and converts it into a received signal (electric signal). In addition, it is used in contact with a measurement object 1 such as a living body such as a breast via a flat plate 2 that is a shape maintaining member. A probe moving means 5, a transmission circuit 7 and a reception circuit 8 are connected to the probe 4. A storage unit 10 is connected to the reception circuit 8, a detection unit 11 is connected to the reception circuit 8 and the storage unit 10, and a probe control unit 6 is connected to the probe moving means 5 and the detection unit 11. A signal control unit 9 is connected to the transmission circuit 7, the reception circuit 8, and the detection unit 11. An image processing unit 12 is connected to the storage unit 10 and the detection unit 11, and an image display unit 13 is connected to the image processing unit 12. The image processing unit 12 and the image display unit 13 or the image display unit 13 may be separated from the measurement device and may be detachably connected to the measurement device as necessary.

During the measurement operation of the measuring device, a signal for transmitting an ultrasonic wave is supplied from the transmission circuit 7 controlled by the signal control unit 9 to the probe 4 in a state where the probe 4 is in contact with the measurement object 1. A flat plate 2 that is a shape maintaining member is disposed between the probe 4 and the measurement target 1, and the measurement target 1 is fixed or maintained in shape by light compression. Further, the gap between the measurement object 1 and the probe 4 may be filled with the acoustic matching agent 3. The probe 4 is moved on the surface of the flat plate 2 by the probe moving means 5, and scanning is performed. The ultrasonic wave transmitted from the probe 4 is reflected by the living tissue of the measurement object 1, received by the probe 4, and converted into a received signal. The reception signal output from the probe is input to the reception circuit 8 that performs signal amplification and A / D conversion, and then stored in the storage unit 10.

Here, the reception time t is defined as t = x / v from the scanning distance x and the scanning speed v of the probe 4 in a region where the measurement target 1 such as a living body does not exist. At this time, when the reception time t of reception signals having substantially the same amplitude continues for a certain period of time, the probe 4 is continuously moved in a region where the measurement target 1 such as a living body does not exist by the detection unit 11 serving as a determination unit. Detects scanning. Considering a case where a breast is detected by fixing a breast with a flat plate 2 and scanning a probe 4 from the flat plate 2, for example, a criterion for determining a region where the measurement target 1 such as a living body does not exist is, for example, Do the following: When the reception time of reception signals having substantially the same amplitude continues for a certain period of time and the corresponding scanning length becomes equal to or longer than a predetermined value (for example, more than three times the length of the flat plate 2). 2), it is determined that the scanning is in the area where the living body does not exist. Based on the determination result, the following operation control can be performed. For example, probe scanning by the probe control unit 6 is stopped, signal transmission / reception is stopped by the signal control unit 9, an imaging processing region is determined by the image processing unit 12, and a reception signal stored in the storage unit 10 is used. Generation of image data and image display by the image display means 13 are performed. By this operation control, it is determined that an image based on the received signal stored in the storage unit 10 should be displayed, the necessary scan is terminated, and the diagnosis time can be shortened. Alternatively, based on the determination result, for example, the direction change and the speed change of the probe scanning can be executed. In this case, after changing the scanning direction to slightly shift the scanning position in the vertical direction, the scanning speed is scanned again at a relatively high speed in the reverse direction in the horizontal direction, and it is determined that the region where the measurement object 1 exists is reached. Return to normal speed and continue scanning. This can also shorten the diagnosis time. In this case, the fixed time is preferably a relatively short time.

An example of the operation control of this embodiment will be described with reference to the plan view of FIG. A scanning line 101 in FIG. 2 indicates a scanning trajectory of the center of the electromechanical transducer in the probe 4. A solid line indicates a scan of a region where the measurement target 1 exists, and a broken line indicates a scan of a region where the measurement target 1 does not exist. Is shown. Reference numeral 102 denotes an element group (each element has one or more cells) of the electromechanical transducer to which attention is paid in order to determine the presence or absence of the measuring object 1. The target element group 102 is composed of a plurality of elements located in the center of the probe 4. For example, the received signal of the target element group 102 is used to determine whether or not a state in which the amplitude is substantially the same continues for a certain period of time. Use for the purpose. The scanning position A is the origin of scanning, and scanning of the probe 4 is started from this position. Since there is no measurement target 1 at the scanning position A (the target element group 102 does not recognize the measurement target 1), the recording operation of the received signal and signal processing (signal amplification, A / D conversion, etc.) are omitted and the scanning speed is increased. Turn into. From the scanning position A to B after the horizontal scanning is started, the horizontal scanning is continued because the element group of interest 102 does not recognize the measurement object 1. A scanning position B indicates a position where the target element group 102 has moved from a region where the measurement target 1 is not present to a certain region. Since the measurement target 1 enters a certain region from the scanning position B, the scanning speed is reduced to a speed preferable for image capturing by executing a recording operation and signal processing of the received signal as an effective region for the measurement target diagnosis.

A scanning position C indicates a position where the target element group 102 has moved from a region where the measurement target 1 is present to a region where it is not present. Since the scan position C deviates from the measurement target 1, the recording operation of the received signal and the signal processing are omitted as an area that is not effective for the measurement target diagnosis, and at the same time, the scanning speed is increased, and the scanning control similar to the scanning position A is performed. The scanning direction is reversed after being shifted in the vertical direction. At the scanning position D, the element group of interest 102 moves from an area where there is no measurement object 1 to a certain area, so that the same imaging control as the scanning position B is performed as an effective area for measurement object diagnosis. Thereafter, scanning control is repeated based on the presence / absence determination of the measuring object 1 at each of the positions E, F, and G, and the flat plate 2 is scanned. With the above operation control, the entire diagnosis time can be shortened by determining the presence or absence of the measurement object 1 and increasing the scanning speed at least in the scanning region that does not contribute to the measurement object diagnosis. Such operation control is set in advance separately from the above determination. Therefore, in this operation control example, in addition to this, when the reception time of reception signals having substantially the same amplitude continues for a certain time (for example, a time corresponding to three times or more the length of the flat plate 2), there is no living body. It is determined that the scanning should be finished following the scanning of the area. Based on the determination result, the probe control unit 6 stops scanning the probe, the signal control unit 9 stops signal transmission / reception, the image processing unit 12 determines the imaging processing area, and the reception stored in the storage unit 10. Using the signal, image data is generated and the image display means 13 displays the image. Thereby, the entire diagnosis time can be further shortened.

(Second Embodiment)
A second embodiment of the measuring apparatus of the present invention will be described with reference to FIG. The present embodiment relates to a PAT (Photoacoustic Tomography) apparatus using a photoacoustic tomography technique that receives an acoustic wave generated in a measurement object by pulse irradiation of light and generates image data.

The PAT apparatus of this embodiment includes a light source 111, an optical component 113, a compression plate 2 that is a shape maintaining member, a probe 4, and a processing unit 30. The image data generated by the processing unit 30 is displayed by the display device 13. The processing unit 30 includes a signal processing unit 20 (a part including the receiving circuit, the storage unit, and the detection unit of the first embodiment) and the image processing unit 12. The light 112 emitted from the light source 111 is guided by an optical component 113 such as a mirror or a lens, and is irradiated to the measurement target 1 such as a living body. When a part of the energy of the light propagated inside the measurement object 1 is absorbed by the light absorber 14 such as a blood vessel (which eventually becomes an acoustic wave generation source), the acoustic absorption is caused by the thermal expansion of the light absorber 14. A wave 17 (typically ultrasound) is generated. The generated acoustic wave 17 is received by the probe 4 and generated as image data (image reconstruction) by subsequent processing. The light source 111 is intended to irradiate light having a specific wavelength that is absorbed by a specific component among components constituting the living body. The light source 111 and the optical component 113 may be provided integrally with the measuring device, or may be provided separately from each other. A laser capable of obtaining a large output is preferable as the light source, but a light emitting diode or the like can be used instead of the laser. The irradiation timing, waveform, intensity, and the like are controlled by the signal processing unit 20 or a control unit (not shown). It is preferable that the light generated from the light source 111 is configured to be movable on the measurement target 1. It is more preferable that the region where light is irradiated onto the measurement target 1 (light irradiated onto the measurement target 1) moves in synchronization with the probe 4.

The shape maintaining member 2 is provided between the measurement object 1 and the probe 4 and is used to keep at least a part of the shape of the measurement object 1 constant, and may have a holding and compression function. Flat plate, compression plate, parallel flat plate, etc. As a material for the shape maintaining member 1, it is preferable to select a material close to the acoustic impedance of the measurement object 1 in order to efficiently receive an acoustic wave. When the measurement target is a breast or the like, it is desirable to use a shape maintaining member made of polymethylpentene. When the shape maintaining member 1 is a flat plate, the thickness of the shape maintaining member is preferably thin considering the attenuation of the acoustic wave, but it is desirable to increase the thickness so that the shape does not deform. The gap between the shape maintaining member 1 and the measuring object 1 or between the shape maintaining member 1 and the probe 4 is an acoustic matching agent having the same acoustic impedance as the shape maintaining member in order to eliminate the gap. It is preferably filled with a liquid such as an acoustic gel or water.

The probe 4 includes one or more elements that receive an acoustic wave and convert it into an electrical signal. The probe 4 uses an electromechanical transducer that uses a piezoelectric phenomenon, an electromechanical transducer that uses light resonance, and changes in capacitance. It consists of an electromechanical conversion device using Any probe 4 may be used as long as it can receive acoustic waves and convert them into electrical signals. Typically, a plurality of elements arranged in a two-dimensional manner is preferable. By using such a two-dimensional array element, acoustic waves can be received simultaneously at a plurality of locations, the reception time can be shortened, and the influence of vibration of the measuring object 1 can be reduced. What has been described about the shape maintaining member, the probe, and the like in this embodiment can also be said with respect to those of the first embodiment. The signal processing performed by the processing unit 30 in FIG. 3 is the same as that in the first embodiment. The display device 13 is a device that displays the image data output from the image processing unit 12 as an image, and typically uses a liquid crystal display or the like. This is also the same as the image display means of the first embodiment. Also in the present embodiment related to the PAT apparatus, the measurement operation can be controlled in the same manner as in the first embodiment.

Even in the PAT apparatus according to the present embodiment, the entire scanning speed can be increased by determining the presence or absence of the measuring object 1 and increasing the scanning speed of the probe in a scanning region that does not contribute to the measuring object diagnosis, or by terminating the scanning at an appropriate point. Diagnosis time can be shortened.

(Third embodiment)
In the third embodiment, in the measurement apparatus shown in FIGS. 1 and 3, a reception signal in a region where a measurement target such as a living body does not exist is stored in advance in a storage unit as a reference signal. As the reference signal, for example, a reception signal derived from air when only air is present, and a reception signal derived from the acoustic matching agent when only the acoustic matching agent is present are stored.

The measurement operation of the measurement apparatus is performed in the same manner as in the first and second embodiments. At this time, when the reference signal stored in the storage unit and the received signal received by the receiving circuit substantially coincide with each other for a predetermined time, the detection unit determines that the probe 4 is scanning an area where the measurement target 1 does not exist. . The criteria for determining the area where the measurement object does not exist is the same when the breast is fixed by a flat plate and breast cancer is detected by scanning the probe from the flat plate. That is, when reception of a reception signal that is substantially the same as the reference signal continues for a predetermined time (for example, when the scanning length corresponding to the predetermined time is three or more times the plate length), judge. Then, based on the determination result, the same measurement operation as in the first and second embodiments is controlled.

The present invention is useful as means for shortening the examination time when there are a large number of subjects and the test areas differ depending on the subjects, such as screening diagnosis of breast cancer.

DESCRIPTION OF SYMBOLS 1 ... Living body (measurement object), 2 ... Flat plate (shape maintenance member), 4 ... Probe, 10 ... Memory | storage part, 11 ... Detection part (determination means)

Claims (6)

A holding member for holding the measurement object;
A light irradiation means for irradiating the measurement object with light;
An electromechanical transducer for receiving a photoacoustic wave generated from the measurement object when irradiated with light by the light irradiating means through the holding member and converting the photoacoustic wave into a received signal is scanned. A measuring device comprising: a probe configured to: a receiving circuit that processes the received signal; and a storage unit that records the received signal processed by the receiving circuit ,
The light irradiation means is configured such that an irradiation region to the measurement object moves in synchronization with the probe,
When the amplitude of the received signal does not substantially change, comprising a determining means for determining that the region scanning position of the probe is not valid for measuring the measurement object, and the determination by the determining means Based on this, the measuring apparatus controls the light irradiation means, and omits processing of the received signal in the receiving circuit or recording of the received signal in the storage unit . The measurement apparatus according to claim 1, wherein a plurality of the electromechanical transducers are provided, and photoacoustic waves generated from the measurement target are received simultaneously at a plurality of locations. The measurement apparatus according to claim 1, wherein the electromechanical conversion device is a device that uses a change in capacitance. 2. The probe according to claim 1, wherein when the determination unit determines that the scanning position of the probe is in an area that is not effective for measuring the measurement target, the probe is scanned at a high speed. 4. The measuring device according to any one of 3 above. The light irradiation from the light irradiation unit is stopped when the determination unit determines that the scanning position of the probe is in an area that is not effective for measuring the measurement target. Item 5. The measuring apparatus according to any one of Items 1 to 4. The storage unit stores a reference signal in advance , and determines whether the scanning position of the probe is in an area that is not effective for measuring the measurement target. 6. The measuring apparatus according to claim 1, wherein comparison is performed.

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