WO2021065800A1

WO2021065800A1 - Temperature-sensitive phantom, and ultrasonic evaluation device in which same is used

Info

Publication number: WO2021065800A1
Application number: PCT/JP2020/036635
Authority: WO
Inventors: 高木　亮; 葭仲　潔
Original assignee: 国立研究開発法人産業技術総合研究所
Priority date: 2019-10-04
Filing date: 2020-09-28
Publication date: 2021-04-08
Also published as: JP7272712B2; JPWO2021065800A1

Abstract

Provided is an ultrasonic evaluation device in which there is employed a temperature-sensitive phantom that has a broader band of temperature sensitivity while maintaining transparency.　This ultrasonic evaluation device is accommodated in an accommodation box and comprises: a temperature-sensitive phantom provided with a plurality of temperature-sensitive phantom members formed so that temperature-sensitive materials are mixed into transparent phantoms, the temperature-sensitive phantom members having substantially the same shape and having different ranges of temperature sensitivity, and the temperature-sensitive phantom being such that the temperature-sensitive phantom members are positioned symmetrically with respect to the longitudinal center axis of the temperature-sensitive phantom; a sheet light source that radiates planar light perpendicular to the longitudinal center axis; and an image sensor that is positioned on an extension line of the longitudinal center axis and captures images of the temperature-sensitive phantom members that have received ultrasonic radiation. The accommodation box accommodates an ultrasonic output element so that the emission direction coincides with the longitudinal center axis and so that ultrasonic waves are focused at the longitudinal center axis.

Description

Temperature-sensitive phantom and ultrasonic evaluation device using it

Regarding the temperature-sensitive phantom and the ultrasonic evaluation device using it.

Since it is provided with a temperature sensor that measures temperature based on electrical resistance or hue, it is necessary to provide an ultrasonic diagnostic system that has high reproducibility and can easily measure a two-dimensional or three-dimensional temperature rise or temperature distribution. As an issue, there is a technique disclosed in Gazette regarding an ultrasonic diagnostic system including a phantom that simulates a temperature rise in a living body and a temperature sensor that is distributed inside the phantom and measures the temperature based on electrical resistance or hue (patented patent). Document 1).

Optical including a microencapsulated thermochromic liquid crystal that emits a temperature-dependent reflection spectrum with the challenge of overcoming the limitations that exist in the evaluation of three-dimensional temperature distribution during High Intensity Focused Ultrasound (HIFU) exposure. In a system in which a transparent temperature-sensitive phantom was made, the three-dimensional temperature distribution was visualized using the optical sheet method, and the temperature distribution of the optical phantom during HIFU exposure was determined with an error of 0.6 ° C., different focusing was performed. There is a technique for visualizing the temperature distribution induced by HIFU exposure using HIFU (Non-Patent Document 1).

In the entire temperature range where the temperature-sensitive liquid crystal changes color depending on the temperature, the temperature can be obtained directly from each brightness of the three primary colors, and the temperature-sensitive liquid crystal can be adjusted according to the temperature with the task of expanding the measured temperature range and improving the accuracy. The entire temperature region that changes the color is divided into a large number of continuous temperature regions in which the relationship between the brightness values of the three primary colors of the temperature-sensitive liquid crystal and the temperature is a monotonically increasing function or a monotonically decreasing function, and the brightness values of the three primary colors in each temperature region. Each range is obtained, and each brightness value of the three primary colors actually obtained by the temperature-sensitive liquid crystal is compared with the brightness value range of the three primary colors in each temperature range, and all three primary colors correspond perfectly and are 1: 1. There is a technique disclosed in Gazette regarding a temperature measurement method using a temperature-sensitive liquid crystal, which determines a specific temperature region to be related and directly calculates the temperature within the specific temperature region by linear interpolation from a brightness value (Patent). Document 2).

Japanese Unexamined Patent Publication No. 2013-85898 Japanese Patent No. 3553048

Here, in the conventional temperature measurement method in which the hue is modulated by the thermochromism effect in which the hue changes due to the temperature change and the temperature distribution is measured, only a certain surface is selectively extracted and the hue is not detected.

In addition, in the technology of kneading a temperature-sensitive material into a transparent phantom, scanning the sheet light with galvanoscan technology to acquire three-dimensional information, and detecting three-dimensional temperature measurement by color tone modulation of the temperature-sensitive material, the material is used. The temperature sensing range was narrow at about 10 ° C.

Further, in the method of color-modulating from the temperature-sensitive liquid crystal, the specific temperature has a one-to-one relationship in which all three primary colors correspond perfectly with each other in comparison with the brightness value range of the three primary colors (R, G, B) in each temperature region. A temperature-sensitive liquid crystal was used in which a region was determined and the temperature was directly calculated by linear interpolation from the brightness value within a specific temperature region.

By the way, ultrasonic therapy equipment that raises the temperature of tissues in the body by focusing and irradiating the living body with strong ultrasonic waves and performs treatment such as cauterizing the tissues is widely used. A phantom that simulates a temperature rise in a living tissue is also known in order to receive ultrasonic waves and grasp the temperature rise in the living body. The phantom simulates the ultrasonic propagation characteristics in the living body, and the typical characteristics of the phantom material are shown in, for example, IEC61391-2. As a method of measuring the temperature distribution inside the phantom, the hue of the phantom is measured using the therm chromism effect (photochromism effect) in which the color of the phantom changes due to temperature changes, and the temperature of the phantom is measured based on the measured hue. The technology to do is also known.

Ultrasound output from the device in the preparatory stage of surgery using ultrasonic therapy equipment that uses strong focused ultrasound (HIFU), or in the process of manufacturing and shipping various ultrasonic output devices that use HIFU. As a means of evaluating the above, research and development are being conducted on whether or not to adopt a temperature-sensitive phantom in which a temperature-sensitive material (mainly cholesteric liquid crystal, etc.) is mixed with a transparent phantom. Further, in recent years, in the field of ultrasonic diagnosis, a technique for diagnosing tissue properties (hardness, etc.) using a relatively high-intensity acoustic radiation pulse that focuses ultrasonic waves with an ultrasonic diagnostic probe has become widespread. , There is a widespread demand for a method for easily evaluating an unnecessary temperature rise in the living body of the acoustic radiation pulse.

When a small amount of temperature-sensitive material is mixed with a transparent phantom, it becomes translucent, but by observing the hue of the temperature-sensitive material (phantom) that generates heat by receiving ultrasonic waves using a light source and an image sensor, the temperature-sensitive phantom It is possible to visualize the temperature rise (heating status) and temperature distribution of the cross section. In order to evaluate the ultrasonic waves output from the device, it is necessary to observe the temperature rise in a temperature range of about 30 ° C. to 40 ° C. However, an amount of cholesteric liquid crystal that is acceptable for maintaining transparency suitable for observation has a temperature sensitivity range of about 10 ° C., and a conventional temperature sensitive phantom has a temperature sensitivity range of 10 ° C. (for example, 40 to 50 ° C., 50 to 50 to 50). There was a problem that only the temperature range of 60 ° C.) could be visualized. It is possible to visualize a wide range of temperatures by mixing temperature-sensitive materials in various temperature ranges (40 to 50 ° C, 50 to 60 ° C, etc.), but if a large amount of temperature-sensitive material is mixed, the temperature-sensitive phantom becomes transparent. There was a problem that the property could not be maintained and the color change of the cross section could not be observed. In fact, there was no temperature-sensitive phantom having a temperature-sensitive range of 30 to 40 ° C. while ensuring transparency. An object of the present invention is to provide a temperature-sensitive phantom having a wider temperature-sensitive range while maintaining transparency, and to provide an ultrasonic evaluation device using the temperature-sensitive phantom.

In order to solve the above problem, the temperature-sensitive phantom according to claim 1 is
A temperature-sensitive phantom with a plurality of temperature-sensitive phantom members having different temperature-sensitive ranges.
Each temperature-sensitive phantom member is formed by mixing a temperature-sensitive material with a transparent phantom.

The temperature-sensitive phantom according to claim 2 is the temperature-sensitive phantom according to claim 1.
A wide range of temperature sensing is covered by making the temperature sensing range of the plurality of temperature sensing phantom members continuous.

The temperature-sensitive phantom according to claim 3 is the temperature-sensitive phantom according to claim 1 or 2.
The plurality of temperature-sensitive phantom members are arranged axially symmetrically with respect to the longitudinal axis of the temperature-sensitive phantom.

The temperature-sensitive phantom according to claim 4 is the temperature-sensitive phantom according to any one of claims 1 to 3.
Each temperature-sensitive phantom member has substantially the same shape.

In order to solve the above problems, the ultrasonic evaluation device according to claim 5 is used.
The temperature-sensitive phantom according to any one of claims 1 to 4,
A light source that irradiates the temperature-sensitive phantom with light,
An image sensor that captures each temperature-sensitive phantom member that has received ultrasonic waves,
To be equipped.

The ultrasonic evaluation device according to claim 6 is the ultrasonic evaluation device according to claim 5.
A storage box for accommodating the temperature-sensitive phantom according to claim 3, the light source, and the image sensor is further provided.
The storage box stores an ultrasonic output element that emits ultrasonic waves to the temperature-sensitive phantom so that the emission direction coincides with the longitudinal axis and the ultrasonic waves are focused on the longitudinal axis.

The ultrasonic evaluation device according to claim 7 is the ultrasonic evaluation device according to claim 6.
The light source is a sheet light source that irradiates planar light perpendicular to the longitudinal axis.
The image sensor is arranged on an extension line of the longitudinal axis.

The ultrasonic evaluation device according to claim 8 is the ultrasonic evaluation device according to claim 7.
Further provided is a moving mechanism for moving the light emitted by the sheet light source in the longitudinal axis direction in the vicinity of the focused position of ultrasonic waves.

The ultrasonic evaluation device according to claim 9 is the ultrasonic evaluation device according to claim 6.
The light source irradiates the entire temperature-sensitive phantom member with light from a direction perpendicular to the longitudinal axis.
The image sensor is arranged on the side opposite to the light source with the temperature-sensitive phantom in between.

The ultrasonic evaluation device according to claim 10 is the ultrasonic evaluation device according to claim 7.
The ultrasonic output element that emits ultrasonic waves to the temperature-sensitive phantom is perpendicular to the boundary surface while maintaining the original emission direction of the ultrasonic waves parallel to the boundary surface. An output child moving mechanism for moving in two axes (X, Y) directions is further provided.

The ultrasonic evaluation device according to claim 11 is the ultrasonic evaluation device according to any one of claims 5 to 10.
The entire ultrasonic evaluation device is shielded from light.

According to the present invention, the temperature sensitive phantom has a wider temperature sensitive range while maintaining transparency.

It is the schematic which shows the structure of the ultrasonic wave evaluation apparatus which concerns on 1st Embodiment. It is a figure explaining the reason why sheet light is used. It is a figure explaining the reason why sheet light is used. It is explanatory drawing which shows the moving mechanism of the light source shown in FIG. It is a side view which shows an example of the temperature sensitive phantom shown in FIG. It is a figure explaining the color change of the temperature-sensitive phantom of two layers when ultrasonic waves are emitted. It is a figure which shows another example of the temperature sensitive phantom shown in FIG. It is a figure explaining the color change of the four temperature sensitive phantom members shown in FIG. 7 about a specific division surface. It is a figure which displays the result of having temperature-converted about the divided plane of FIG. 8 in consideration of symmetry. It is a temperature map which visualized the temperature width 40 degreeC of time: t1 to t4 by summing up the images of FIG. It is a figure which shows the modification of the temperature sensitive phantom shown in FIG. 7. It is the schematic which shows the structure of the ultrasonic wave evaluation apparatus which concerns on 2nd Embodiment. It is a figure explaining the color change of the two-layer temperature sensitive phantom member when ultrasonic waves are emitted asymmetrically. It is a figure explaining the color change of the four temperature sensitive phantom members shown in FIG. 7 when ultrasonic waves are emitted asymmetrically. It is a photograph of an actual temperature-sensitive phantom seen from an image sensor. (A) shows an actual temperature-sensitive phantom, and (b) shows a state of temperature change when a strong focused ultrasonic wave (HIFU) is irradiated from the back to the front of the paper surface.

(First Embodiment)
An ultrasonic evaluation device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing the configuration of the ultrasonic wave evaluation device 1 according to the first embodiment. The ultrasonic evaluation device 1 includes a temperature-sensitive phantom 10 that indicates a temperature rise or temperature distribution by hue (change in shade and gradation of color), and a light source 20 that irradiates the temperature-sensitive phantom 10 with planar light (sheet light). And an image sensor 30 that captures an image of the temperature-sensitive phantom 10 that has been irradiated with ultrasonic waves, and is housed in a light-shielding box 32 displayed by a broken line. Further, the probe 42 of the ultrasonic output device 40 is arranged on an extension line of the longitudinal axis of the temperature-sensitive phantom 10, and is housed in the light-shielding box 32 so that the emission direction of ultrasonic waves matches the longitudinal axis. The probe 42 is a focusing type single disk element using a titanium / lead zirconate tit (PZT) piezoelectric material, a composite piezoelectric material, or the like, or a plurality of elements using these materials arranged in an array in a focusing type / planar type. You can pick up what you have done. In the case of the focusing type, the focusing region (point) of the emitted ultrasonic waves is, and in the case of the flat type, the focusing region (point) generated by adjusting the ultrasonic emission timing (time) delay of each element is the longitudinal axis of the temperature sensitive phantom 10. Arranged to focus on. Further, the probe 42 is arranged in contact with the temperature sensitive phantom 10 in order to satisfactorily propagate the ultrasonic wave to the temperature sensitive phantom 10. The ultrasonic evaluation device 1 also has a device control unit 50 that moves and scans the light source 20 in the longitudinal direction (the movement mechanism will be described later) and acquires an image by the image sensor 30, and converts the temperature from the acquired image. It also has an arithmetic processing unit 52 that reconstructs the temperature rise region into a two-dimensional or three-dimensional image, and an image display unit 54 that displays the temperature rise region of the temperature-sensitive phantom 10.

Here, the temperature-sensitive phantom 10 uses a transparent material such as acrylamide, agar (agar), or urethane, which has close to biological characteristics, as a base material, and a temperature-sensitive material such as cholesteric liquid crystal is mixed at a concentration of, for example, 0.1% or less. It is formed by curing. The light source 20 irradiates the sheet light from a direction perpendicular to the ultrasonic emission direction so as to include all of the divided surfaces perpendicular to the longitudinal axis in the vicinity of the ultrasonic focusing position in the temperature sensitive phantom 10. The light source 20 moves in the longitudinal axis direction of the temperature-sensitive phantom 10 by a moving mechanism (not shown) described later. The image sensor 30 is configured to include a CCD, CMOS, or the like, and images the temperature rise of the divided surface (sheet light irradiation surface) of the temperature-sensitive phantom 10 to image it. The ultrasonic output device 40 includes a consumer ultrasonic output device for a humidifier and a sensor, in addition to a medical ultrasonic diagnostic probe for the purpose of treatment and diagnosis.

(Reason for using sheet light)
2 and 3 are diagrams for explaining the reason why the sheet light is used for observing the temperature distribution of the temperature-sensitive phantom 10. FIG. 2A shows an image of an image acquired by the image sensor 30 when the temperature-sensitive phantom 10 is irradiated with sheet light, and FIG. 2B shows an image of FIG. 2A in the longitudinal direction. An image is shown in which a plurality of images are acquired to reconstruct the three-dimensional temperature distribution of the temperature-sensitive phantom 10. FIG. 3 shows an image of an image acquired by the image sensor 30 when the temperature-sensitive phantom 10 is irradiated with normal spot light from the front, the side surface, an oblique direction, or the like. When sheet light is used for observing the temperature-sensitive phantom 10, the image obtained by irradiating the sheet light is only the image of the sheet light irradiation surface. As a result, the temperature distribution of the temperature-sensitive phantom 10 on the irradiation surface can be grasped (FIG. 2A). By acquiring a plurality of these images in the longitudinal direction of the temperature-sensitive phantom 10, the temperature distribution region of the temperature-sensitive phantom 10 can be reconstructed in three dimensions (FIG. 2B). On the other hand, when ordinary spot light is used for observing the temperature-sensitive phantom 10, the entire temperature-sensitive phantom is illuminated because the ordinary spot light is adopted. The image acquired by the image sensor 30 is an image of the temperature distribution stacked in the longitudinal axis direction of the temperature sensitive phantom 10. Since the temperature distributions overlap, the temperature distribution region of the temperature-sensitive phantom 10 cannot be grasped in three dimensions (FIG. 3). By acquiring images of a plurality of divided surfaces at different positions in the longitudinal axis direction of the temperature-sensitive phantom 10 using sheet light, the temperature distribution region of the temperature-sensitive phantom 10 can be accurately grasped in three dimensions.

(Light source movement mechanism)
FIG. 4 is an explanatory diagram showing a moving mechanism of the light source 20 shown in FIG. As a method of moving the light source 20, for example, a method of directly moving the light source 20 itself to move the sheet light irradiation surface (FIG. 4A), a method of fixing the position of the light source 20 and moving the light emitting position to move the sheet light. A method of moving the irradiation surface (FIG. 4B) can be considered. In the former, as shown in FIG. 4A, the light source 20 is moved in the longitudinal axis direction of the temperature-sensitive phantom 10 by the moving stage 22 under the control of the device control unit 50, and the sheet light irradiation surface is moved. In the latter, as shown in FIG. 4B, the position of the light source 20 is fixed, the galvanometer mirror 24 is moved in the longitudinal axis direction of the temperature sensitive phantom 10 under the control of the device control unit 50, and the sheet light irradiation is performed. Move the face. In addition to this, a method of moving the slit inside the light source 20 can be considered (not shown).

(Conversion between living body and temperature sensitive phantom)
When the amplitude absorption coefficient α in the living body is set to the peak intensity I, the calorific value q per unit volume is

I can do it. Further, in the soft tissue of the ultrasonic frequency f, the amplitude absorption coefficient α is

Can be approximated to. The heat transfer phenomenon in the living body can be described by the bioheat transport equation (3).

ρ, C _p , and k are the density, specific heat, and thermal conductivity in the living body, and W _b , c _b , and T _b are blood flow, specific heat and temperature of blood.

Since the intense focused ultrasonic therapy is a high-intensity irradiation in a relatively short time, the amount of heat generated by the blood flow can be ignored as compared with the calorific value q, so that the equation (3) can be written as (4).

Whether or not the size of the heat conduction term on the right side of equation (4) can be ignored compared to the calorific value q depends on the steepness of the distribution of the temperature T. Now, assuming that the dimension of the strongly focused ultrasonic focal region is d, the irradiation time τ _c

When the irradiation time is shorter, the heat conduction k can be ignored. Therefore, the equation (4) can be approximated as follows.

When the temperature rise ΔT immediately before the ultrasonic irradiation is set to the irradiation time Δt (≦ τ _c ),

Is estimated. When it is d to 1 mm, it is about 10 s.

The various parameters of the temperature sensitive phantom [Delta] T _T of the formula _{(7), α T, ρ} T, C pT and the various parameters of the biological _{_{ΔT B, α B = X ·}} α T, ρ B = Y · ρ T, C _{Let pB} = Z · C _pT . X, Y, and Z are the ratios of the temperature-sensitive phantom and the parameters of the living body (various parameters of the temperature-sensitive phantom can be measured in advance, and the ratio with the known biological parameters can be calculated).

Pre-measured temperature-sensitive phantom parameter density ρ, specific heat C _p , ultrasonic absorption coefficient α temperature-sensitive phantom and actual known organ parameters (density ρ, specific heat C _p , ultrasonic absorption coefficient α) If the ratio (X, Y, Z) is known, the actual temperature rise of the living body can be estimated. The conventional temperature-sensitive phantom has a temperature sensitivity range of 10 ° C., and the actual temperature rise of the living body is also the living body temperature rise conversion coefficient × 10 ° C. However, the temperature-sensitive phantom proposed by the present invention has a living body temperature rise conversion coefficient × 40. The temperature becomes ℃ (in principle, 50 ℃ and 60 ℃ are possible), and it becomes possible to visualize the temperature rise in the living body which is a constant multiple of the conventional one. Therefore, the present invention is not limited to a specific width of 40 ° C., but can visualize a region having a temperature width that is a constant multiple of the conventional one.

(Two-layered temperature-sensitive phantom)
FIG. 5 is a side view showing an example of the temperature-sensitive phantom shown in FIG. The temperature-sensitive phantom 12 is composed of temperature-

sensitive phantom members

12a and 12b having a rectangular parallelepiped shape having an upper and lower two-layer structure overlapping in a horizontal plane including a longitudinal axis. The upper temperature sensitive phantom member 12a has a first temperature sensitive range of 40 to 50 ° C., and the lower temperature sensitive phantom member 12b has a second temperature sensitive range of 50 to 60 ° C. The probe 42 is arranged so that the emitted ultrasonic waves are focused on a horizontal plane including the longitudinal axis of the temperature-sensitive phantom 10. FIG. 6 is a diagram illustrating each color change imaged by the image sensor 30 when ultrasonic waves are emitted from the probe 42. FIG. 6A is a diagram for explaining the change in color of the temperature-sensitive phantom 12 with time, and FIG. 6B is a diagram in which the color change of the temperature-sensitive phantom 12 is reconstructed. The temperature-

sensitive phantom members

12a and 12b are in a plane-symmetrical positional relationship with respect to the boundary surface (horizontal plane). Alternatively, it can be said that the temperature-

sensitive phantom members

12a and 12b have an axisymmetric positional relationship with respect to the longitudinal axis (center of the horizontal plane in the figure).

Here, the two temperature-

sensitive phantom members

12a and 12b preferably have substantially the same shape. As used herein in this context, the term "substantially identical shape" is used for manufacturing or other purposes as long as it is in a plane-symmetrical position with respect to the horizontal plane, including the longitudinal axis, in addition to the same shape. It is intended to include slightly different shapes. In one preferred embodiment, the temperature-

sensitive phantom members

12a and 12b have a plane-symmetrical positional relationship with respect to the horizontal plane including the longitudinal axis or an axially symmetric positional relationship with respect to the longitudinal axis, and the temperature-

sensitive phantom members

12a and 12b have a positional relationship of the temperature-sensitive phantom. It also includes the case where the peripheral region away from the longitudinal axis is slightly different within the range in which the degree of temperature rise and the temperature distribution thereof do not interfere with the observation from the image sensor (see FIG. 1).

Further, for the temperature-sensitive phantom 12, a method in which the temperature-

sensitive phantom members

12a and 12b are separately produced and the two temperature-

sensitive phantom members

12a and 12b are bonded together, or a temperature-sensitive phantom member 12a is produced and used as a base material. It is formed by a method of producing a temperature-sensitive phantom member 12b by arranging a mixed solution with the temperature-sensitive material at a position in contact with the temperature-sensitive phantom member 12a and curing the mixture.

When the probe 42 emits ultrasonic waves to the temperature-sensitive phantom 12, the temperature-sensitive phantom 12 near the focusing position where the ultrasonic waves focus changes in color at different times, and the image captured by the image sensor 30 is also shown in FIG. It changes as shown in (a). That is, when the temperature-sensitive phantom 10 starts to rise in temperature in response to ultrasonic waves and the temperature-sensitive phantom 12 reaches the first temperature-sensitive range (40 to 50 ° C.) after a predetermined time elapses, the upper temperature-sensitive phantom member 12a Is observed to be visualized. When ultrasonic waves are continuously emitted, the temperature of the temperature-sensitive phantom 10 rises further, exceeds the first temperature-sensitive range (time: t1), and reaches the second temperature-sensitive range (50 to 60 ° C.). The color of the temperature-sensitive phantom member 12a in the upper layer disappears, while the visualization of the temperature-sensitive phantom member 12b in the lower layer is observed. Further, when ultrasonic waves are continuously emitted and the temperature sensitive phantom 10 is further heated (time: t2), the temperature is further increased from the second temperature sensitive range, and the color of the lower temperature sensitive phantom member 12b disappears.

FIG. 6 (b) is a diagram in which this series of color changes of the temperature-sensitive phantom 10 is reconstructed by the arithmetic processing unit 52 (FIG. 1). It is assumed that the ultrasonic waves are emitted plane-symmetrically (or can be said to be "axisymmetric with respect to the longitudinal axis") with respect to the horizontal plane including the longitudinal axis. Visualization of the temperature-

sensitive phantom members

12a and 12b in the upper and lower layers is arranged in the time axis direction (FIG. 6 (a)), and the images are synthesized and reconstructed to enable visualization in a wide temperature range (FIG. 6). 6 (b)). In this example, the temperature range of 40 to 60 ° C. and the temperature range of 20 ° C. are visualized. Since the temperature sensitive ranges of the two temperature

sensitive phantom members

12a and 12b are continuous, a series of color changes of the temperature sensitive phantom 12 are displayed.

When the probe 42 is arranged so that the emission direction of the ultrasonic waves matches the longitudinal axis of the temperature-sensitive phantom 10, the colors of the upper and lower two layers of the temperature-sensitive phantom 10 are changed by the ultrasonic waves with respect to the horizontal plane including the longitudinal axis. It changes in a plane symmetric manner. When it is observed that the hues of the upper and lower two layers of the temperature-sensitive phantom 10 are not plane-symmetrical, the probe 42 does not emit ultrasonic waves symmetrically. This makes it possible to evaluate the symmetry of the ultrasonic waves emitted by the probe 42. Further, since the progress of the temperature rise of the temperature-sensitive phantom 12 is observed over time, the continuity of the output of the probe 42 can be evaluated.

The two-layered temperature-sensitive phantom 12 has described an example in which the temperature-

sensitive phantom members

12a and 12b are in a plane-symmetrical positional relationship with respect to the horizontal plane, but the present invention is not limited to this. For example, the two temperature-sensitive phantom members may be arranged so as to have a plane-symmetrical positional relationship with respect to a vertical plane (not shown). In such an arrangement, it can be said that the two temperature-sensitive phantom members are in an axially symmetrical positional relationship with respect to the longitudinal axis of the temperature-sensitive phantom.

The ultrasonic evaluation device 1 has described an example in which the temperature-sensitive phantom 10, the light source 20, and the image sensor 30 are housed in a light-shielding box 32, but the present invention is not limited to this. For example, it may be an ultrasonic evaluation device in which a temperature-sensitive phantom, a light source, and an image sensor are housed in a storage box having a transparent window for observing the operating state of the device. It is also possible to operate the entire device with light shielding, such as covering it with a dark curtain cloth at the time of use or installing the device in a dark room.

(Temperature-sensitive phantom with four temperature-sensitive ranges)
FIG. 7 is a diagram showing another example of the temperature sensitive phantom shown in FIG. 1 as viewed from the image sensor 30. The temperature-sensitive phantom 14 can be divided into four in a horizontal plane including a longitudinal central axis and a vertical plane. In each section, temperature-

sensitive phantom members

14a, 14b, 14c, and 14d having the same rectangular parallelepiped shape but different temperature sensing ranges are arranged in an axisymmetric relationship with respect to the longitudinal central axis. The first temperature-sensitive phantom member 14a has a first temperature-sensitive range of 40 to 50 ° C., and the second temperature-sensitive phantom member 14b has a second temperature-sensitive range of 50 to 60 ° C. and a third feeling. The warm phantom member 14c has a third temperature sensitive range of 60 to 70 ° C., and the fourth temperature sensitive phantom member 14d has a fourth temperature sensitive range of 70 to 80 ° C. As a result, the temperature-sensitive phantom 14 covers the temperature-sensitive range of 40 to 80 ° C. required to properly capture the ultrasonic waves emitted by the probe 42 as a whole.

Similar to the example of the temperature-sensitive phantom 12 shown in FIG. 5, when the probe 42 (FIG. 1) emits ultrasonic waves to the temperature-sensitive phantom 14, four temperature-sensitive phantom members are located near the focusing position where the ultrasonic waves are focused. 14a, 14b, 14c, 14d change color at different times. FIG. 8 is a diagram for explaining the hues of the four temperature-

sensitive phantom members

14a, 14b, 14c, and 14d imaged by the image sensor 30 with respect to the specific divided surface. The temperature-sensitive phantom 14 was heated by receiving ultrasonic waves, and with the passage of time, each of the temperature-

sensitive phantom members

14a, 14b, 14c, and 14d was visualized within the respective temperature-sensitive range, and the image sensor 30 was visualized. Observe the temperature-sensitive phantom 14 (FIGS. 8 (a) to 8 (d)).

When the temperature-sensitive phantom 14 begins to rise in temperature in response to ultrasonic waves and the first temperature-sensitive phantom member 14a reaches the first temperature-sensitive range (40 to 50 ° C.) after a predetermined time elapses, the first temperature-sensitive phantom member 14a reaches the first temperature sensing range (40 to 50 ° C.). It is observed that the phantom member 14a is visualized (FIG. 8 (a)). When ultrasonic waves are continuously emitted, the temperature of the temperature-sensitive phantom 14 rises, exceeds the first temperature-sensitive range (time: t1), reaches the second temperature-sensitive range (50 to 60 ° C.), and becomes the first. While the color of the temperature-sensitive phantom member 14a disappears, the second temperature-sensitive phantom member 14b is visualized (FIG. 8 (b)). When ultrasonic waves are continuously emitted, the temperature of the temperature-sensitive phantom 14 rises further, exceeds the second temperature-sensitive range (time: t2), and reaches the third temperature-sensitive range (60 to 70 ° C.). While the color of the second temperature-sensitive phantom member 14b disappears, the third temperature-sensitive phantom member 14c is visualized (FIG. 8 (c)). When ultrasonic waves are continuously emitted, the temperature of the temperature-sensitive phantom 14 rises further, exceeds the third temperature-sensitive range (time: t3), and reaches the fourth temperature-sensitive range (70 to 80 ° C.). While the color of the third temperature-sensitive phantom member 14c disappears, the visualization of the fourth temperature-sensitive phantom member 14d is observed (FIG. 8 (d)). When ultrasonic waves are continuously emitted and the temperature of the temperature-sensitive phantom 14 is further increased (time: t4), the temperature is further increased from the fourth temperature-sensitive range, and the color disappears from the fourth temperature-sensitive phantom member 14d.

The arithmetic processing unit 52 (FIG. 1) that acquired the temperature rise image of the divided surface (sheet light irradiation surface) of the temperature-sensitive phantom 14 imaged by the image sensor 30 (FIG. 1) has the symmetry of the four divisions of the temperature-sensitive phantom 14. In consideration of (FIG. 7), the temperature is converted from the image for each divided surface, and the temperature rise region is reconstructed into a two-dimensional image. FIG. 9 is a diagram showing the result of temperature conversion for a specific divided surface in consideration of symmetry. FIG. 10 is a temperature map in which the images of FIG. 9 are added up for a specific divided surface and the temperature range of 40 ° C. at time: t1 to t4 is visualized. Since the temperature sensitive ranges of the four temperature

sensitive phantom members

14a, 14b, 14c, and 14d are continuous, a series of color changes of the temperature sensitive phantom 14 are displayed. By synthesizing four images using the longitudinal central axis as an index, visualization in a wide temperature range becomes possible. In this example, the temperature range of 40 to 80 ° C. and the temperature range of 40 ° C. can be visualized. When the probe 42 emits ultrasonic waves symmetrically, the hues of the four temperature-

sensitive phantom members

14a, 14b, 14c, and 14d change axisymmetrically with respect to the longitudinal central axis. When it is observed that the four hues are not axisymmetric, the probe 42 does not emit ultrasonic waves symmetrically. This makes it possible to evaluate the symmetry of the ultrasonic waves emitted by the probe 42. Further, since the progress of the temperature rise of the temperature-sensitive phantom 14 is observed over time, the continuity of the output of the probe 42 can be evaluated.

The reason why the temperature-sensitive phantom 14 is irradiated with the sheet light is to visualize the temperature rise of the surface of interest (the divided surface (sheet light irradiation surface)). By using sheet light, it is possible to irradiate only the surface of interest (although it has a width of several mm), so that an image of the surface of interest can be acquired by the image sensor 30 (FIG. 1). By scanning the temperature-sensitive phantom 14 and taking images one by one using the moving mechanism of the light source 20 shown in FIG. 4, it is possible to grasp the three-dimensional temperature rise near the ultrasonic focusing position.

(Modification example)
FIG. 11 is a diagram showing a modified example of the temperature sensitive phantom 14 shown in FIG. 7. In the four types of temperature-sensitive phantoms 16, the temperature-sensitive phantom members 16a ₁ and 16a ₂ , 16b ₁ and 16b ₂ , 16c ₁ and 16c ₂ , 16d ₁ and 16d ₂ having the same temperature sensing range are axes centered on the longitudinal central axis. They are arranged symmetrically (FIG. 11 (a)). When the probe 42 emits ultrasonic waves symmetrically, the hues of the two opposing temperature-sensitive phantom members 16a ₁ and 16a ₂ , 16b ₁ and 16b ₂ , 16c ₁ and 16c ₂ , 16d ₁ and 16d ₂ are longitudinal centers. It changes axisymmetrically with respect to the axis (FIG. 11 (b)). When the probe 42 is not axisymmetric with respect to the longitudinal central axis (FIG. 11 (c)), the probe 42 does not emit ultrasonic waves symmetrically. This makes it possible to evaluate the symmetry of the ultrasonic waves emitted by the probe 42.

_{Here, the two temperature-sensitive phantom members 16a 1} and 16a ₂ arranged axially symmetrically with respect to the longitudinal central axis have "substantially the same shape". More specifically, in addition to the same shape, the positional relationship is axisymmetric with respect to the longitudinal central axis, and the degree of temperature rise of the temperature-sensitive phantom and its temperature distribution hinder observation from the image sensor (see FIG. 1). It also includes the case where the peripheral area away from the longitudinal axis is slightly different within the range. _{Similarly, the temperature-sensitive phantom members 16b 1} and 16b ₂ , 16c ₁ and 16c ₂ , 16d ₁ and 16d ₂ arranged axially symmetrically with respect to the longitudinal central axis also have "substantially the same shape".

As described above, if a plurality of temperature-sensitive phantom materials are arranged axisymmetrically with respect to the longitudinal central axis, the symmetry of the ultrasonic waves emitted by the contacts can be evaluated, so the number of temperature-sensitive phantom materials is here. The number is not limited to 2, 4, and 8 mentioned in the above, and may be 3 or 5 or more. Further, in FIGS. 6 and 7, the temperature-

sensitive phantoms

12 and 14 are shown to have a square cross section perpendicular to the longitudinal axis, but the present invention is not limited to this. For example, the cross section may be rectangular or circular.

In the temperature-sensitive phantom 14 shown in FIG. 7, the first temperature-sensitive phantom member 14a has a first temperature-sensitive range of 40 to 50 ° C., and the second temperature-sensitive phantom member 14b has a second temperature-sensitive phantom member 14b of 50 to 60 ° C. The third temperature-sensitive phantom member 14c has a third temperature-sensitive range of 60 to 70 ° C., and the fourth temperature-sensitive phantom member 14d has a fourth temperature-sensitive range of 70 to 80 ° C. An example has been described, but the present invention is not limited to this. For example, the first temperature-sensitive phantom member 14a and the fourth temperature-sensitive phantom member 14d have a first temperature-sensitive range of 40 to 50 ° C., and the second temperature-sensitive phantom member 14b has a second temperature-sensitive phantom member 14b of 50 to 60 ° C. The same temperature sensing region (first temperature sensing range) is centered on the longitudinal central axis, such that the third temperature sensing phantom member 14c has a third temperature sensing range of 60 to 70 ° C. It may be arranged axisymmetrically. Alternatively, the first temperature-sensitive phantom member 14a and the second temperature-sensitive phantom member 14b have a first temperature-sensitive range of 40 to 50 ° C., and the third temperature-sensitive phantom member 14c has a third temperature-sensitive phantom member 14c of 50 to 60 ° C. The same temperature sensing region (first temperature sensing range) is not necessarily centered on the longitudinal central axis, such that the fourth temperature sensing phantom member 14d has a third temperature sensing range of 60 to 70 ° C. Even if they are arranged adjacent to each other instead of being axisymmetric, the temperature sensing ranges of the plurality of temperature sensing phantom members may be continuous.

(Second Embodiment)
FIG. 12 is a schematic view showing the configuration of the ultrasonic evaluation device 101 according to the second embodiment suitable for observing the two-layered temperature-sensitive phantom 12. The same or similar elements as those of the ultrasonic evaluation device 1 according to the first embodiment are designated by the same or similar reference numerals, and the description thereof will be omitted. The ultrasonic evaluation device 1 according to the first embodiment fixes the probe 42 and images the divided surface of the temperature-sensitive phantom 10, whereas the ultrasonic evaluation device 101 according to the second embodiment is described below. As described, the difference is that the probe 42 is moved to image the temperature-sensitive phantom 12 (FIG. 5). Even when the symmetry of the ultrasonic wave emission direction cannot be ensured, it is effective because the probe 42 can be moved to take an image. The ultrasonic evaluation device 101 maintains the probe 42 so that the original emission direction of the ultrasonic wave is parallel to the boundary surface of the two temperature-

sensitive phantom members

12a and 12b (FIG. 5), and the probe 42 A probe moving mechanism (not shown) for moving the probe 42 in two axes (X, Y) directions perpendicular to the boundary surface, and a movement control unit 150 for controlling the movement of the probe 42 are provided.

FIG. 13 is a diagram for explaining the color change of the temperature-sensitive phantom 12 imaged by the image sensor 30 when ultrasonic waves are asymmetrically emitted from the probe 42. 13 (a) and 13 (b) are diagrams for explaining the change in color of the temperature-sensitive phantom 12 with time, and FIG. 13 (c) is a diagram reconstructing the color change of the temperature-sensitive phantom 12. The probe 42 is moved to the temperature-sensitive phantom member 12a in a state where the light source 20 irradiates the surface perpendicular to the original emission direction of the ultrasonic waves with the sheet light. Ultrasonic waves are emitted from the probe 42 to the temperature-sensitive phantom 12 (temperature-sensitive phantom member 12a). The sheet light irradiation surface is moved in the longitudinal axis direction near the ultrasonic focusing position, and the temperature-sensitive phantom 12 (temperature-sensitive phantom member 12a) is scanned by the image sensor 30 (FIG. 13 (a)). As a result, the three-dimensional temperature distribution of the temperature-sensitive phantom member 12a is visualized. Subsequently, the probe moving mechanism (not shown) moves the probe 42 to the temperature-sensitive phantom member 12b, and similarly, ultrasonic waves are emitted from the probe 42 to the temperature-sensitive phantom member 12b to generate ultrasonic waves. The temperature-sensitive phantom member 12b is scanned by moving the sheet light irradiation surface in the longitudinal axis direction near the focusing position (FIG. 13 (b)). As a result, the three-dimensional temperature distribution of the temperature-sensitive phantom member 12b is visualized. By synthesizing and reconstructing the two acquired three-dimensional temperature distributions as in the case of the first embodiment, it is possible to visualize the axially asymmetric temperature rise region with a temperature width twice that of the conventional one (FIG. 13 (FIG. 13). c)). Since the finally acquired temperature distribution is synthesized and reconstructed, it does not matter which of the temperature-

sensitive phantom members

12a and 12b the observation is started from.

(Temperature phantom with 4 temperature ranges)
If a temperature-sensitive phantom having four temperature-sensitive ranges shown in FIG. 7 is used, even a probe of an ultrasonic output device whose symmetry in the emission direction of ultrasonic waves cannot be ensured can be moved to take an image. The axially asymmetric temperature rise region can be visualized with double the temperature width. FIG. 14 is a diagram for explaining the color change of the four temperature-sensitive phantom members shown in FIG. 7 when ultrasonic waves are emitted asymmetrically. The temperature-sensitive phantom 14 was heated by receiving ultrasonic waves, and with the passage of time, each of the temperature-

sensitive phantom members

14a, 14b, 14c, and 14d was visualized within the respective temperature-sensitive range, and the image sensor 30 was visualized. Observe the temperature-sensitive phantom 14 (FIGS. 14 (a) to 14 (d)). The probe 42 is moved to the temperature-sensitive phantom member 14a in a state where the light source 20 irradiates the surface perpendicular to the original emission direction of the ultrasonic waves with the sheet light. The image sensor 30 scans the temperature-sensitive phantom member 14a by emitting ultrasonic waves to irradiate the sheet light (FIG. 14A) to visualize the three-dimensional temperature distribution of the temperature-sensitive phantom member 14a. This is repeated for the temperature-

sensitive phantom members

14b, 14c, 14d, and the visualized temperature-sensitive phantom 14 is observed (FIGS. 14 (b) to 14 (d)). By synthesizing and reconstructing the four acquired three-dimensional temperature distributions, it is possible to visualize the axially asymmetric temperature rise region with a temperature width four times that of the conventional one.

A temperature-sensitive phantom having four temperature-sensitive ranges shown in FIG. 7 was actually produced. A thermosetting urethane material was used as the base material of the temperature-sensitive phantom. Then, in order to obtain a sensitivity range of 40 ° C to 50 ° C, a cholesteric liquid crystal (model number: KXN-4050) of Nippon Capsule Products is used, and in a sensitivity range of 50 ° C to 60 ° C, the same liquid crystal (model number: KXN-5060) is used. The same liquid crystal (model number: KXN-6070) is used in the sensitivity range of 60 ° C to 70 ° C, and the same liquid crystal (model number: KXN-7080) is used in the sensitivity range of 70 ° C to 80 ° C. A temperature-sensitive phantom was prepared by mixing it with a base material at a concentration of (urethane) = about 0.05% and curing it.

FIG. 15 shows a temperature-sensitive phantom actually produced. FIG. 15 is a photograph of an actual temperature-sensitive phantom seen from an image sensor (see FIG. 1). (A) shows an actual temperature-sensitive phantom, and the arrangement of the four temperature-sensitive ranges corresponds to the arrangement of FIG. 7. (B) shows the state of temperature change when strong focused ultrasonic waves (HIFU) are irradiated from the back to the front of the paper surface. As shown in FIG. 15 (b), the change in the sensitivity range from 40 ° C. to 80 ° C. described with reference to FIGS. 8 (a) to 8 (d) could be actually observed.

1: Ultrasonic evaluation device, 10: Temperature sensitive phantom,
12: Temperature-sensitive phantom, 12a: Upper-layer temperature-sensitive phantom member, 12b: Lower-layer temperature-sensitive phantom member,
14: Temperature-sensitive phantom, 14a: First temperature-sensitive phantom member, 14b: Second temperature-sensitive phantom member, 14c: Third temperature-sensitive phantom member, 14d: Fourth temperature-sensitive phantom member,
16: Temperature-sensitive phantom, 16a ₁ , 16a ₂ , 16b ₁ , 16b ₂ , 16c ₁ , 16c ₂ , 16d ₁ , 16d ₂ : Temperature-sensitive phantom member,
20: Light source, 22: Moving stage, 24: Galvano mirror, 30: Image sensor, 32: Shading box, 40: Ultrasonic output device, 42: Detector, 50: Device control unit, 52: Arithmetic processing unit, 54 : Image display,
101: Ultrasonic evaluation device, 150: Movement control unit

Claims

A temperature-sensitive phantom with a plurality of temperature-sensitive phantom members having different temperature-sensitive ranges.
Each temperature-sensitive phantom member is a temperature-sensitive phantom formed by mixing a temperature-sensitive material with a transparent phantom.
The temperature-sensitive phantom according to claim 1, which covers a wide range of temperature-sensing by making the temperature-sensing ranges of the plurality of temperature-sensitive phantom members continuous.
The temperature-sensitive phantom according to claim 1 or 2, wherein the plurality of temperature-sensitive phantom members are arranged axially symmetrically with respect to the longitudinal axis of the temperature-sensitive phantom.
The temperature-sensitive phantom according to any one of claims 1 to 3, wherein each temperature-sensitive phantom member has substantially the same shape.
The temperature-sensitive phantom according to any one of claims 1 to 4,
A light source that irradiates the temperature-sensitive phantom with light,
An image sensor that captures each temperature-sensitive phantom member that has received ultrasonic waves,
An ultrasonic evaluation device.
A storage box for accommodating the temperature-sensitive phantom according to claim 3, the light source, and the image sensor is further provided.
5. The storage box stores an ultrasonic output element that emits ultrasonic waves to the temperature-sensitive phantom so that the emission direction coincides with the longitudinal axis and the ultrasonic waves are focused on the longitudinal axis. The ultrasonic evaluation device according to.
The light source is a sheet light source that irradiates planar light perpendicular to the longitudinal axis.
The ultrasonic evaluation device according to claim 6, wherein the image sensor is arranged on an extension line of the longitudinal axis.
The ultrasonic evaluation device according to claim 7, further comprising a moving mechanism for moving the light emitted by the sheet light source in the longitudinal axis direction near the focused position of ultrasonic waves.
The light source irradiates the entire temperature-sensitive phantom member with light from a direction perpendicular to the longitudinal axis.
The ultrasonic evaluation device according to claim 6, wherein the image sensor is arranged on the opposite side of the temperature-sensitive phantom from the light source.
The ultrasonic output element that emits ultrasonic waves to the temperature-sensitive phantom is perpendicular to the boundary surface while maintaining the original emission direction of the ultrasonic waves parallel to the boundary surface. The ultrasonic evaluation device according to claim 7, further comprising an output child moving mechanism for moving in two axes (X, Y) directions.
The ultrasonic evaluation device according to any one of claims 5 to 10, wherein the entire ultrasonic evaluation device is shielded from light.