JP7671508B2 - Temperature distribution information acquisition device and program - Google Patents

Description

This disclosure relates to a temperature distribution information acquisition device and program.

Patent Document 1 discloses a device that converts the CT values of each part of an object (e.g., muscle and fat) measured by an X-ray CT device into temperature to obtain information about the temperature distribution of the object.

Patent No. 6483473

Images captured by X-ray CT scanners contain a lot of noise, which causes variations (standard deviation) in the CT values, and these variations are also reflected in the temperature values converted from the CT values. When image information is generated in which temperature values are color-mapped in the temperature distribution information acquired by the device described in Patent Document 1, there is a possibility that the displayed color will differ from the actual temperature due to the influence of image noise. In other words, it may be difficult to accurately recognize the temperature value of each part.

This disclosure has been made in consideration of these problems, and provides a temperature distribution information acquisition device and program that can acquire temperature distribution information with reduced effects of image noise.

(1) According to a first aspect of the present disclosure, a temperature distribution information acquisition device includes a calculation unit that calculates the variation in CT values of an object to be inspected from a CT image, a setting unit that converts the variation in CT values to temperature variation using a conversion table that indicates the relationship between the CT values of the object to be inspected and the temperature, and sets a temperature resolution for the object to be inspected based on the variation in temperature, a conversion unit that converts the CT value of the object to temperature in the CT image using the conversion table, and a generation unit that generates temperature distribution information that visualizes the distribution of the temperature of the object to be inspected in a display mode that differs for each temperature range based on the set temperature resolution.

(2) According to a second aspect of the present disclosure, in the temperature distribution information acquisition device according to the first aspect, the calculation unit accepts designation of a region of interest within the object of examination and calculates the variation in the CT value within the region of interest.

(3) According to a third aspect of the present disclosure, in the temperature distribution information acquisition device according to the first or second aspect, the generation unit creates a lookup table in which a different color is set for each of the temperature ranges, and generates the temperature distribution information using the lookup table.

(4) According to a fourth aspect of the present disclosure, the temperature distribution information acquisition device according to any one of the first to third aspects further includes an image processing unit that performs image processing on the CT image to reduce image noise, the calculation unit calculates the variation in the CT value of the test object from the CT image after the image processing, and the conversion unit converts the CT value of the test object in the CT image after the image processing to the temperature.

(5) According to a fifth aspect of the present disclosure, the temperature distribution information acquisition device according to any one of the first to fourth aspects further includes a display unit that displays the temperature distribution information superimposed on the CT image.

(6) According to a sixth aspect of the present disclosure, the program causes a temperature distribution information acquisition device to execute the steps of: calculating the variation in CT values of the test object from a CT image; converting the variation in CT values to temperature variation using a conversion table that represents the relationship between the CT values of the test object and the temperature, and setting a temperature resolution for the test object based on the temperature variation; converting the CT value of the test object in the CT image to temperature using the conversion table; and generating temperature distribution information that visualizes the distribution of the temperature of the test object in a display mode that differs for each temperature range based on the set temperature resolution.

The temperature distribution information acquisition device and program disclosed herein can acquire temperature distribution information with reduced effects of image noise.

1 is a diagram showing an overall configuration of a temperature distribution information acquisition system according to the present invention. 4 is a block diagram for explaining a functional configuration of a processor of the temperature distribution information acquisition device of the present invention. FIG. 4 is a first flowchart showing an example of processing of the temperature distribution information acquisition device of the present invention. FIG. 2 is a first diagram for explaining the function of the temperature distribution information acquisition device of the present invention. FIG. 4 is a diagram showing an example of a conversion table according to the present invention; FIG. 13 is a diagram showing an example of the temperature resolution for each organ according to the present invention. 11 is a second flowchart showing an example of processing by the temperature distribution information acquisition device of the present invention. FIG. 2 is a second diagram for explaining the function of the temperature distribution information acquisition device of the present invention. FIG. 13 is a block diagram illustrating a functional configuration of a processor of a temperature distribution information acquisition device in a modified example of the present invention.

First Embodiment
Hereinafter, a temperature distribution information acquisition system 1 and a temperature distribution information acquisition device 20 according to a first embodiment of the present disclosure will be described with reference to FIGS. 1 to 8. FIG.

(Overall configuration of temperature distribution information acquisition system)
FIG. 1 is a diagram showing the overall configuration of a temperature distribution information acquisition system according to the present invention.
The temperature distribution information acquisition system 1 according to the present invention is a system for displaying an image of the temperature distribution inside an object to be inspected. The object to be inspected is a living body such as a patient undergoing treatment such as thermotherapy, cauterization, or cryotherapy. The object to be inspected is not limited to a human being, and in other embodiments, an animal may be the object to be inspected. In still other embodiments, a non-living body such as food (e.g., fermented food) may be the object to be inspected. In this embodiment, the object to be inspected is a living body. As shown in FIG. 1, the temperature distribution information acquisition system 1 includes an X-ray CT (Computed Tomography) device 10 and a temperature distribution information acquisition device 20.

The X-ray CT device 10 irradiates a living body with X-rays and measures the amount of X-ray transmission (the amount of X-rays that have passed through the living body). The X-ray CT device 10 irradiates a living body with X-rays from multiple directions, measures the amount of X-ray transmission for each direction, analyzes the measurement results, and calculates the CT value for each part of the living body. The X-ray CT device 10 then transmits a CT image capable of detecting the calculated CT value to the temperature distribution information acquisition device 20. An existing X-ray CT device can be used as the X-ray CT device 10.

The CT value is a relative value that indicates the degree of X-ray absorption, with air being -1000 and water being 0, and is expressed in units of HU (Hounsfield Unit). The CT value can be calculated, for example, using the method described in Patent Document 1.

The temperature distribution information acquisition device 20 calculates temperature distribution information of the living body based on the CT value received from the X-ray CT device 10, and displays the temperature distribution of the target object as an image. As shown in FIG. 1, the temperature distribution information acquisition device 20 is configured using a computer including, for example, a processor 200, a memory 201, a storage 202, an interface 203, a display unit 204, and an operation reception unit 205.

The processor 200 controls the overall operation of the temperature distribution information acquisition device 20.

Memory 201 stores instructions and data for processor 200 to operate based on a program.

Storage 202 is a so-called auxiliary storage device, and may be, for example, a hard disk drive (HDD) or a solid state drive (SSD).

The interface 203 is an interface (communication interface) for connecting to the X-ray CT device 10 so that communication is possible.

The display unit 204 is a display that displays temperature distribution information.

The operation reception unit 205 is an input device that receives input operations by the operator of the temperature distribution information acquisition device 20, and may be, for example, a general mouse, keyboard, touch sensor, etc.

(Functional configuration of temperature distribution information acquisition device)
FIG. 2 is a block diagram for explaining the functional configuration of the processor of the temperature distribution information acquisition device of the present invention.
As shown in FIG. 2, the processor 200 of the temperature distribution information acquisition device 20 operates according to a predetermined program to function as a calculation unit 2001, a setting unit 2002, a conversion unit 2003, and a generation unit 2004.

The calculation unit 2001 calculates the variation in CT values of a living body from the CT images.

The setting unit 2002 converts the CT number variation into a temperature variation using a conversion table that represents the relationship between the CT number and temperature of the living body, and sets the temperature resolution for the living body based on the temperature variation.

The conversion unit 2003 converts the CT value of the living body in the CT image into temperature using a conversion table.

The generating unit 2004 generates temperature distribution information that visualizes the temperature distribution of the living body in a display mode that differs for each temperature range based on the set temperature resolution. The generating unit 2004 creates, for example, a lookup table in which a different color is set for each temperature range, and generates temperature distribution information using the lookup table.

(Processing flow of the temperature distribution information acquisition device)
FIG. 3 is a first flowchart showing an example of processing performed by the temperature distribution information acquisition device of the present invention.
First, the flow of the temperature resolution setting process by the temperature distribution information acquisition device 20 will be described in detail with reference to Fig. 3. Here, an example will be described in which the temperature distribution information acquisition device 20 acquires temperature distribution information inside the body of a patient undergoing treatment such as thermotherapy, cauterization, or cryotherapy (particularly, the area where the treatment is performed).

The temperature distribution information acquisition device 20 acquires a CT image from the X-ray CT device 10 (step S01). This CT image is displayed on the display unit 204 of the temperature distribution information acquisition device 20.

Next, the operation reception unit 205 of the temperature distribution information acquisition device 20 receives an operation by the operator to specify the target region R1 and the region of interest R2 on the CT image (step S02).

FIG. 4 is a first diagram for explaining the function of the temperature distribution information acquisition device of the present invention.
As shown in Fig. 4, the display unit 204 displays a CT image of the patient acquired from the X-ray CT device 10. While viewing the CT image displayed on the display unit 204, the operator performs an operation to specify a target region R1 for generating temperature distribution information of the patient and a region of interest R2. The target region R1 is, for example, a region indicating an organ to be treated. The region of interest R2 is a region within the target region R1 in which the CT value is closer to uniform, and for example, the operator visually checks the CT image to determine the position for setting the region of interest R2.

At this time, the range of the target region R1 and the region of interest R2 may be manually specified by the operator using the operation reception unit 205 (e.g., a mouse).

When the operator specifies a point on the CT image, the calculation unit 2001 of the temperature distribution information acquisition device 20 may automatically set the range of the target region R1 and the region of interest R2 based on the point. For example, the calculation unit 2001 may use known image processing to extract the contour of an organ (e.g., muscle, fat, liver, kidney, etc.) present around the specified point on the CT image, and set the area within this contour as the target region R1. The calculation unit 2001 may also set a circular region a predetermined distance from the specified point on the CT image as the region of interest R2. The predetermined distance may be a fixed value set in advance for each organ, or the operator may specify an arbitrary value. The region of interest is not limited to a circle, and may be another shape, such as a rectangle.

Note that multiple target regions R1 may be set. Furthermore, when multiple target regions R1 are set, one region of interest R2 is set for each target region R1.

Next, the calculation unit 2001 calculates the variation in CT values within the region of interest R2 of the target region R1 (step S03). Here, the calculation unit 2001 calculates the standard deviation SD (σ _CT ) of the CT values.

When a plurality of target regions R1 (for example, four organs T1 to T4) are set, the calculation unit 2001 calculates the standard deviation SD (σ _CT1 to σ _CT4 ) of the CT values for each target region R1.

Furthermore, the setting unit 2002 converts the variation in the CT values into a variation in temperature (step S04). Specifically, the setting unit 2002 converts the standard deviation SD (σ _CT ) of the CT values into a standard deviation SD (σ _T ) of the temperature by the following formula (1).

In equation (1), f'(T) is the slope of the function f(T) (hereinafter also referred to as the "conversion table") that represents the relationship between the CT value and the temperature.

FIG. 5 is a diagram showing an example of a conversion table according to the present invention.
5 is a graph showing a linear approximation of the relationship between the CT value and temperature of each of a plurality of organs T1 to T4 of a living body. For example, the organs T1 to T4 are the liver, muscle, kidney, and fat, respectively. These graphs are obtained in advance based on the measured values of the CT value and temperature of each organ T1 to T4 (for example, the liver, muscle, kidney, and fat), and are recorded in the storage 202 as a conversion table used for converting the CT value to temperature. The same conversion table may be used for all patients.

In addition, a conversion table may be prepared for each group, for example, classified by gender, age, height, weight, etc., and the conversion table corresponding to the group to which the patient belongs may be used.

For example, assume that an organ T1 is set as the target region R1 in step S02. In this case, the setting unit 2002 converts the standard deviation SD (σ CT ) of the CT value of the organ T1 into the standard deviation SD (σ _T ) of the temperature by using the slope f'( _T ) of the conversion table for the organ T1.

In addition, when multiple target regions R1 (e.g., four organs T1 to T4) are set, the setting unit 2002 converts the standard deviation SD of the CT values (σ _CT1 to σ _CT4 ) into the standard deviation SD of the temperature (σ _T1 to σ _T4 ) for each target region R1.

Next, the setting unit 2002 sets the temperature resolution in the target region R1 based on the standard deviation SD ( _σT ) of the temperature (step S05). For example, the setting unit 2002 sets _2σT (i.e., the range of ± _σT ), which is twice _the standard deviation SD (σT), as the temperature resolution of the target region R1.

FIG. 6 is a diagram showing an example of the temperature resolution for each organ according to the present invention.
As in the example of FIG. 6, when a plurality of target regions R1 (for example, four organs T1 to T4) are set, the setting unit 2002 sets the temperature resolution of each target region.

In the example of Fig. 6, the setting unit 2002 substitutes the standard deviation SD ( _σCT1 = 1.3) of the CT value of the organ T1 calculated by the calculation unit 2001 and the slope (-0.5) of the conversion table for the organ T1 into the above formula (1), and converts it into the standard deviation SD ( _σT1 = 2.6) of the temperature. The setting unit 2002 also sets the temperature resolution of the organ T1 to "5.2", which is _2σT . Similarly, the setting unit 2002 sets the temperature resolution of the other target regions R1 (organs T2, T3, T4).

When a single CT image includes multiple target regions R1, the setting unit 2002 may set one temperature resolution to be applied to the entire CT image in accordance with the target region R1 with the highest (worst) temperature resolution. In the example of FIG. 6, the setting unit 2002 sets the temperature resolution of the organ T3 (9.4) as the highest, and thus rounds up the temperature resolution of this organ T3 to 10.0, as the temperature resolution of the entire CT image.

The temperature distribution information acquisition device 20 performs the series of processes shown in FIG. 3 once, for example, immediately before treating a patient. When treating another patient, the temperature distribution information acquisition device 20 performs the series of processes shown in FIG. 3 again to set the temperature resolution according to the patient.

In addition, if the imaging conditions of the X-ray CT device 10 are changed during treatment of a patient, the variation in CT values may change. In this case, the temperature distribution information acquisition device 20 may perform the series of processes in FIG. 3 again to update the temperature resolution for this patient.

FIG. 7 is a second flowchart showing an example of the process of the temperature distribution information acquisition device of the present invention.
Next, the flow of the temperature distribution information generation process by the temperature distribution information acquisition device 20 will be described in detail with reference to Fig. 7. When the setting of the temperature resolution is completed by the series of processes in Fig. 3, the temperature distribution information acquisition device 20 executes the process of generating temperature distribution information of the target region during treatment.

First, as shown in FIG. 7, the temperature distribution information acquisition device 20 acquires a CT image from the X-ray CT device 10 (step S11). This CT image is displayed on the display unit 204 of the temperature distribution information acquisition device 20.

Next, the conversion unit 2003 converts the CT value of the target region R1 into temperature using the conversion table f(T) for the target region R1 (step S12).

Next, the generating unit 2004 creates a lookup table D1 (FIG. 8) in which a different color is assigned to each temperature range based on the temperature resolution set by the setting unit 2002, and generates temperature distribution information D2 (FIG. 8) in which the temperature distribution of the target region R1 is color-coded using this lookup table D1 (step S13).

FIG. 8 is a second diagram for explaining the function of the temperature distribution information acquisition device of the present invention.
As shown in Fig. 8, the lookup table D1 is a table in which a predetermined temperature range is divided into gradations with a temperature resolution of 2σ _T , and a different color is set for each gradation. In the example of Fig. 8, the temperature range is -20°C to 60°C, and the temperature resolution is 10.0°C. Therefore, the lookup table D1 is divided into eight gradations, and a different color is set for each gradation. As shown in Fig. 8, the lookup table D1 may be displayed on the display unit 204 so that the operator can understand the correspondence between the color and the temperature. The lookup table D1 may also include information indicating the body temperature of the patient when the CT image was taken.

The generation unit 2004 references the lookup table D1 and generates temperature distribution information D2, which is an image in which each part (each pixel) of the target region R1 is painted with a color corresponding to the temperature.

The display unit 204 also superimposes the temperature distribution information D2 generated by the generation unit 2004 on the CT image (step S14). This allows the operator to easily grasp the temperature distribution of the target region R1 (the patient's treatment area) on the CT image.

The temperature distribution information acquisition device 20 may perform the series of processes shown in FIG. 7 each time a CT image is taken before, during, and after performing thermotherapy on a patient. This allows the operator to perform treatment while checking whether the treatment area is at an appropriate temperature.

(Functions and Effects of Temperature Distribution Information Acquisition Device)
As described above, the temperature distribution information acquiring device 20 according to the present invention obtains the temperature variation from the CT number variation of a living body (test subject) in a CT image, and sets the temperature resolution for the living body based on this temperature variation. The temperature distribution information acquiring device 20 also generates temperature distribution information in which the distribution of temperatures converted from the CT number of the living body is visualized in a display mode (color) that differs for each temperature range based on the temperature resolution.

By doing this, the temperature distribution information acquisition device 20 can acquire temperature distribution information with reduced temperature variation caused by image noise.

The temperature distribution information acquisition device 20 also superimposes this temperature distribution information on the CT image.

By doing this, the temperature distribution information acquisition device 20 can allow the operator to easily understand whether the temperature distribution within the living body has been brought to an appropriate state through treatment such as hyperthermia.

<Modification>
FIG. 9 is a block diagram for explaining the functional configuration of a processor of a temperature distribution information acquisition device in a modified example of the present invention.
As shown in FIG. 9 , the processor 200 of the temperature distribution information acquisition device 20 according to the modified example may further function as an image processing unit 2005 .

The image processing unit 2005 performs image processing to reduce image noise in the CT image received from the X-ray CT device 10. The image processing is, for example, a smoothing process.

In a modified example of the present invention, in step S01 of FIG. 3, the image processing unit 2005 performs image processing (such as smoothing processing) on the CT image acquired from the X-ray CT device 10 to reduce image noise. In this case, in step S03 of FIG. 3, the calculation unit 2001 calculates the variation in CT values based on the CT image after image processing.

Similarly, in step S11 of FIG. 7, the image processing unit 2005 performs image processing on the CT image acquired from the X-ray CT device 10 to reduce image noise. In this case, in step S12 of FIG. 7, the conversion unit 2003 converts the CT value into temperature based on the CT image after image processing.

By doing this, the temperature distribution information acquisition device 20 can acquire temperature distribution information with reduced effects of image noise.

As described above, several embodiments of the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and gist of the invention.

REFERENCE SIGNS LIST 1 Temperature distribution information acquisition system 10 X-ray CT apparatus 20 Temperature distribution information acquisition apparatus 200 Processor 2001 Calculation unit 2002 Setting unit 2003 Conversion unit 2004 Generation unit 2005 Image processing unit 201 Memory 202 Storage 203 Interface 204 Display unit 205 Operation reception unit

Claims (6)

A calculation unit that calculates the variation in CT value of the inspection object from the CT image;
a setting unit that converts the variation in the CT number into a variation in temperature using a conversion table that indicates a relationship between the CT number and the temperature of the object to be inspected, and sets a temperature resolution for the object to be inspected based on the variation in temperature;
a conversion unit that converts the CT value of the object in the CT image into a temperature using the conversion table;
a generating unit that generates temperature distribution information by imaging the distribution of the temperature of the inspection object in a display mode that differs for each temperature range based on the set temperature resolution;
A temperature distribution information acquisition device comprising: The calculation unit receives a designation of a region of interest within the examination object, and calculates a variation in the CT value within the region of interest.
The temperature distribution information acquisition device according to claim 1 . the generating unit creates a lookup table in which a different color is set for each of the temperature ranges, and generates the temperature distribution information using the lookup table.
The temperature distribution information acquisition device according to claim 1 . An image processing unit that performs image processing on the CT image to reduce image noise,
The calculation unit calculates a variation in the CT value of the object from the CT image after the image processing,
The conversion unit converts the CT value of the object in the CT image after the image processing into the temperature.
The temperature distribution information acquiring device according to claim 1 . a display unit that displays the temperature distribution information superimposed on the CT image,
The temperature distribution information acquiring device according to claim 1 . Calculating the variation in CT value of the object from the CT image;
converting the variation in the CT number into a variation in temperature using a conversion table that indicates a relationship between the CT number and the temperature of the object to be inspected, and setting a temperature resolution for the object to be inspected based on the variation in temperature;
converting the CT value of the object in the CT image into a temperature using the conversion table;
generating temperature distribution information by imaging the distribution of the temperature of the inspection object in a display mode that differs for each temperature range based on the set temperature resolution;
A program for causing a temperature distribution information acquisition device to execute the above.

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