JP7385213B2 - Non-rigid image registration adjustment support device, non-rigid image registration adjustment support method and program - Google Patents

Description

The present invention relates to a non-rigid image registration adjustment support device, a non-rigid image registration adjustment support method, and a program.

In recent years, software that uses non-rigid image registration (DIR) technology (see Non-Patent Literature 1, Non-Patent Literature 2, and Non-Patent Literature 3) has been used to create treatment plans in medical settings. ing.

Richard Castillo et al., “A framework for evaluation of deformable image registration spatial accuracy using large landmark point sets”, Phys. Med. Biol. 54 (2009) 1849-1870 Martha M. Coselmon et al., “Mutual information based CT registration of the lung at exhale and inhale breathing states using thin-plate splines”, Med. Phys. 31(11), November 2004, 2942-2948 David Sarrut et al., “Simulation of four-dimensional CT images from deformable registration between inhale and exhale breath-hold CT scans”, Med. Phys. 33(3), March 2006, 605-617

By the way, in the DIR technology used in such medical settings, the DIR performance is evaluated in advance using images of the patient's organs, and the DIR parameters may be suitably adjusted based on the evaluation results. . The performance of DIR is evaluated by the smallness of the difference between the image after transformation by DIR and the image obtained by imaging. In general, not limited to DIR, in order to evaluate the difference between two images, things that are common between the two images are found, and based on the common things, the extent to which the things that are not common are different is evaluated. For example, in rigid body registration, regardless of the image to be transformed, the relative positional relationship between each position of the object to be imaged in the image after transformation, such as the outline of the object to be imaged or the area inside the contour, is the same as before the transformation. does not change. That is, in rigid body registration, the relative positional relationship between each position of the object to be photographed is preserved regardless of the image to be deformed. Therefore, in rigid body registration, the difference between the deformed image and the photographed image is evaluated based on the relative positional relationship.

However, since the deformation by DIR is non-rigid deformation, the relative positional relationship of each position of the image, such as the distance between the vertices of the image reflected in the image and the angle of the vertices, is not necessarily preserved. Therefore, in DIR, candidates for common matters for evaluating DIR performance may differ depending on the image to be transformed, and the reliability of DIR performance evaluation results may be low.

As a means of solving such problems, there is a method in which the adjuster compares two images and specifies many common positions on the images that are found visually. The adjuster is a person who evaluates the performance of DIR and makes adjustments based on the evaluation results. However, in such a case, there is a problem in that the burden on the adjuster is heavy because the adjuster needs to judge and give instructions about many common positions.

In view of the above circumstances, an object of the present invention is to reduce the labor of an adjuster who adjusts non-rigid image registration (DIR: Deformable Image Registration).

One aspect of the present invention is to execute DIR for performing non-rigid image registration (DIR: Deformable Image Registration) on a first image that is a photographing result of a first physical phantom that is a physical phantom that imitates part or all of a human body. first physical phantom information that is information indicating the shape and size of the first physical phantom; and a shape and size of a second physical phantom that is a physical phantom that partially differs in shape from the first physical phantom. second physical phantom information that is information indicating the size; image position information on the first phantom that is information indicating the position of the image shown by the first image on the first physical phantom; image position information on the second phantom, which is information indicating the position on the second physical phantom of an image shown by a second image that is a photographing result; and image position information on the second phantom, which is a part of the first physical phantom. geometric information that is information indicating a relationship expressed by geometry that does not use coordinates between a part with a different shape and a part that is part of the second physical phantom and has a different shape from the first physical phantom; , a coincidence degree acquisition unit that acquires information indicating the degree of coincidence between the DIR execution result by the DIR execution unit and a second image that is the photographing result of the second physical phantom, based on . This is a registration adjustment support device.

One aspect of the present invention is the non-rigid image registration adjustment support device described above, wherein the geometric information includes a part of the first physical phantom that is different in shape from the second physical phantom, and This indicates that a portion that is part of the second physical phantom and has a different shape from the first physical phantom is in a similar relationship.

One aspect of the present invention is the non-rigid image registration adjustment support device described above, wherein the geometric information includes a part of the first physical phantom that is different in shape from the second physical phantom, and This indicates that a portion of the second physical phantom that is different in shape from the first physical phantom is in an enlarged or reduced relationship.

One aspect of the present invention is the non-rigid image registration adjustment support device described above, in which the first image includes a first physical phantom that is a coordinate system for indicating the shape and size of the first physical phantom. The second image does not include an image indicating the position of the origin of the coordinate system, and the second image does not include the position of the origin of the second physical phantom coordinate system, which is a coordinate system for indicating the shape and size of the second physical phantom. There is no image showing this.

One aspect of the present invention is the non-rigid image registration adjustment support device described above, further comprising a DIR updating section that updates the DIR based on the degree acquired by the coincidence degree acquisition section.

One aspect of the present invention is the non-rigid image registration adjustment support device described above, in which the physical phantom has one or more parts that can be inserted and removed.

One aspect of the present invention is the above-described non-rigid image registration adjustment support device, in which a part or all of the removable parts have a shape, size, and number that have a smaller influence on DIR than a predetermined influence. and has a solid body of position.

One aspect of the present invention is the non-rigid image registration adjustment support device described above, in which the physical phantom is a physical phantom that imitates the waist of a human body.

One aspect of the present invention is to execute DIR for performing non-rigid image registration (DIR: Deformable Image Registration) on a first image that is a photographing result of a first physical phantom that is a physical phantom that imitates part or all of a human body. step, first physical phantom information that is information indicating the shape and size of the first physical phantom, and a shape and size of a second physical phantom that is a physical phantom that partially differs in shape from the first physical phantom. second physical phantom information that is information indicating the size; image position information on the first phantom that is information indicating the position of the image shown by the first image on the first physical phantom; image position information on the second phantom, which is information indicating the position on the second physical phantom of an image shown by a second image that is a photographing result; and image position information on the second phantom, which is a part of the first physical phantom. geometric information that is information indicating a relationship expressed by geometry that does not use coordinates between a part with a different shape and a part that is part of the second physical phantom and has a different shape from the first physical phantom; , a matching degree obtaining step of obtaining information indicating the degree of matching between the DIR execution result in the DIR execution step and a second image that is the photographing result of the second physical phantom, based on the non-rigid image. This is a registration adjustment support method.

One aspect of the present invention is a program for causing a computer to function as the above-mentioned non-rigid image registration adjustment support device.

According to the present invention, it is possible to provide a technique that reduces the labor of an adjuster who adjusts DIR.

FIG. 1 is a diagram showing an example of a functional configuration of a DIR adjustment support system 100 according to an embodiment. The figure which shows an example of the functional structure of the control part 21 in embodiment. 7 is a flowchart illustrating an example of a process flow in which the inter-original-image correspondence information acquisition unit 212 acquires inter-original-image correspondence information in the embodiment. FIG. 4 is an explanatory diagram illustrating a deformation vector field in the embodiment. 12 is a flowchart illustrating an example of a process flow in which the matching degree acquisition unit 214 acquires the DIR matching degree in the embodiment. 2 is a flowchart illustrating an example of the flow of processing executed by the DIR adjustment support device 2 of the embodiment. FIG. 1 is a first perspective view showing an example of a physical phantom 3 according to an embodiment. FIG. 8 is a diagram showing parts of the pelvis imitated by part P1, part P2, part P3, and part P5 of the physical phantom 3 of the embodiment shown in FIG. 7; FIG. 3 is a second perspective view showing an example of the physical phantom 3 of the embodiment. FIG. 3 is a diagram showing an example of a cross section of a physical phantom 3 according to an embodiment. FIG. 3 is a diagram showing an example of the shape of the physical phantom 3 in the depth direction of the embodiment. FIG. 3 is a diagram illustrating an example of a shape that satisfies the axiomatic system of non-Euclidean geometry but does not satisfy the axiom system of Euclidean geometry. The figure which shows an example of the image reflected in the 1st phantom image, and an example of the image reflected in the 2nd phantom image in the relationship of enlargement or reduction of a modification.

(Embodiment)
FIG. 1 is a diagram showing an example of a functional configuration of a DIR adjustment support system 100 according to an embodiment.
<Overview of DIR adjustment support system 100>
First, an overview of the DIR adjustment support system 100 will be explained.
The DIR adjustment support system 100 includes a first physical phantom (hereinafter referred to as "first physical phantom") and a second physical phantom (hereinafter referred to as "second physical phantom") whose shape is partially different from the first physical phantom. ). The physical phantom to be imaged is a physical phantom that imitates part or all of a human body.

Hereinafter, the image of the first physical phantom will be referred to as a first phantom image. Hereinafter, the image of the second physical phantom will be referred to as a second phantom image. Hereinafter, a region having the same shape and size in the first physical phantom and the second physical phantom will be referred to as an anatomically matched region.

The DIR adjustment support system 100 uses the first phantom image and the second phantom image to evaluate the performance of the non-rigid image registration that is the evaluation target and the adjustment target, and further adjusts the parameters of the non-rigid image registration. do. More specifically, the DIR adjustment support system 100 first evaluates the performance of non-rigid image registration (DIR) to be adjusted. Hereinafter, the process of evaluating DIR performance will be referred to as DIR evaluation process.

Next, the DIR adjustment support system 100 updates the parameters of the DIR to be adjusted if the evaluation result does not meet a predetermined standard (hereinafter referred to as "passing standard"). Hereinafter, the process of updating the DIR parameters to be adjusted will be referred to as DIR update process. DIR parameters include, for example, the DIR range, DIR grid size, and smoothing coefficient.

The DIR adjustment support system 100 improves the performance of the DIR to be adjusted by repeating the DIR evaluation process and the DIR update process until the acceptance criteria are met. Hereinafter, the process of repeating the DIR evaluation process and the DIR update process until the acceptance criteria are met will be referred to as the DIR adjustment process.
This concludes the explanation of the outline of the DIR adjustment support system 100.

<Details of DIR adjustment support system 100>
The DIR adjustment support system 100 includes an imaging unit 1 that acquires a first phantom image and a second phantom image, and a DIR adjustment support device 2 that improves DIR performance based on the first phantom image and the second phantom image. .

The imaging unit 1 includes a laser light source 11 and an imaging device 12.
The laser light source 11 emits laser. In FIG. 1, the laser is laser L. The laser emitted by the laser light source 11 is irradiated onto one location on the physical phantom 3. In FIG. 1, for example, a position S on the physical phantom 3 is irradiated. The physical phantom 3 in FIG. 1 is a first physical phantom or a second physical phantom.

The imaging device 12 photographs an image of an object located within a photographing range. The imaging device 12 may be of any type as long as it can take an image of an object located within the imaging range. The imaging device 12 may be, for example, a CT (Computed Tomography) or a device that generates an image using an MRI (Magnetic Resonance Imaging). Specifically, the objects located within the imaging range are a first physical phantom and a second physical phantom.

Here, details of the positions where the first physical phantom and the second physical phantom are installed will be explained. In the DIR adjustment support system 100, the first physical phantom is located within the imaging range and satisfies the condition that a predetermined position on the first physical phantom is irradiated with the laser (hereinafter referred to as "first installation"). (referred to as "location"). Hereinafter, a predetermined position on the first physical phantom that is irradiated with a laser will be referred to as a first irradiation position.

In the DIR adjustment support system 100, the second physical phantom is located at a position within the imaging range where a predetermined position on the second physical phantom is irradiated with a laser (hereinafter referred to as "second installation position"). ). Hereinafter, a predetermined position on the second physical phantom that is irradiated with a laser will be referred to as a second irradiation position.

The first irradiation position is the position of the origin of the first physical phantom coordinate system. The first physical phantom coordinate system is a coordinate system used when the DIR adjustment support system 100 evaluates the performance of non-rigid image registration, and is a coordinate system used to indicate the positional relationship between the origin and each position on the first physical phantom. It is a coordinate system. Therefore, the first physical phantom coordinate system is a coordinate system used to indicate the shape and size of the first physical phantom. The second irradiation position is the position of the origin of the second physical phantom coordinate system. The second physical phantom coordinate system is a coordinate system used when the DIR adjustment support system 100 evaluates the performance of non-rigid image registration, and is a coordinate system used to indicate the positional relationship between the origin and each position on the second physical phantom. It is a coordinate system. Therefore, the second physical phantom coordinate system is a coordinate system used to indicate the shape and size of the second physical phantom.

The first irradiation position is an anatomical matching site of the first physical phantom. The second irradiation position is the origin of the second physical phantom coordinate system. The second irradiation position is an anatomical matching site of the second physical phantom. The positional relationship between the first irradiation position and other anatomically matching parts of the first physical phantom is the same as the positional relationship between the second irradiating position and other anatomically matching parts of the second physical phantom. The first irradiation position and the second irradiation position are located outside the imaging range.
This concludes the detailed explanation of the positions where the first physical phantom and the second physical phantom are installed.

The imaging device 12 generates a first phantom image by photographing a first physical phantom installed at a first installation position. The imaging device 12 generates a second phantom image by photographing a second physical phantom installed at a second installation position.

Image data of the first phantom image (hereinafter referred to as “first phantom image data”) generated by the imaging device 12 is transmitted to the DIR adjustment support device 2. Image data of the second phantom image (hereinafter referred to as “second phantom image data”) generated by the imaging device 12 is transmitted to the DIR adjustment support device 2.

The DIR adjustment support device 2 evaluates the performance of the non-rigid image registration to be evaluated and to be adjusted based on the acquired first phantom image data and second phantom image data. Further, the DIR adjustment support device 2 adjusts the parameters of the non-rigid image registration based on the acquired first phantom image data and second phantom image data.

The DIR adjustment support device 2 includes a control unit 21 including a processor 91 such as a CPU (Central Processing Unit) and a memory 92 connected via a bus, and executes a program. The DIR adjustment support device 2 functions as a device including a control section 21, a communication section 22, a storage section 23, an input section 24, and an output section 25 by executing a program.

Note that all or part of each function of the DIR adjustment support device 2 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). good. The program may be recorded on a computer-readable recording medium. The computer-readable recording medium is, for example, a portable medium such as a flexible disk, magneto-optical disk, ROM, or CD-ROM, or a storage device such as a hard disk built into a computer system. The program may be transmitted via a telecommunications line.

The control unit 21 controls the operation of each functional unit included in the own device (DIR adjustment support device 2). Further, the control unit 21 executes DIR adjustment processing.

The communication unit 22 includes a communication interface for connecting its own device to the imaging unit 1 . The communication unit 22 communicates with the imaging unit 1 via wireless or wired communication. The communication unit 22 receives, for example, first phantom image data and second phantom image data generated by the imaging device 12 through communication with the imaging unit 1.

The storage unit 23 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The storage unit 23 stores, for example, a DIR program to be adjusted. The storage unit 23 stores, for example, image data of an image after conversion by DIR. The storage unit 23 stores, for example, the received first phantom image data and second phantom image data.

The storage unit 23 stores first physical phantom information in advance. The first physical phantom information is information indicating the shape and size of the first physical phantom. Specifically, the first physical phantom information is information expressed by the first physical phantom coordinate system. The first physical phantom information is, for example, a coordinate value of each position of the first physical phantom in the first physical phantom coordinate system.

The storage unit 23 stores second physical phantom information in advance. The second physical phantom information is information indicating the shape and size of the second physical phantom. Specifically, the second physical phantom information is information expressed by the second physical phantom coordinate system. The second physical phantom information is, for example, a coordinate value of each position of the second physical phantom in the second physical phantom coordinate system.

The storage unit 23 stores information indicating the position of the image represented by the first phantom image on the first physical phantom (hereinafter referred to as "image position information on the first phantom"). The information indicating the position on the first physical phantom of the image indicated by the first phantom image indicates, for example, the first installation position, the position of the laser light source 11, the position of the imaging device 12, and the angle of view of the imaging device 12. information and information indicating the direction in which the laser beam is emitted by the laser light source 11.

The storage unit 23 stores information indicating the position of the image indicated by the second phantom image on the second physical phantom (hereinafter referred to as "image position information on the second phantom"). The information indicating the position of the image indicated by the second phantom image on the second physical phantom indicates, for example, the second installation position, the position of the laser light source 11, the position of the imaging device 12, and the angle of view of the imaging device 12. information and information indicating the direction in which the laser beam is emitted by the laser light source 11.

The storage unit 23 stores the positional relationship between the first irradiation position and other anatomically matching parts of the first physical phantom, and the positional relationship between the second irradiating position and other anatomically matching parts of the second physical phantom. stores information indicating that they are the same (hereinafter referred to as "irradiation position correspondence information").

The storage unit 23 stores information (hereinafter referred to as "geometric information") indicating a relationship expressed by geometry that does not use coordinates between the shape of a non-identical part in the first phantom and the shape of a non-identical part in the second phantom. ). The non-identical portion is a portion that is different between the first physical phantom and the second physical phantom. The geometric information is, for example, information that the shapes of the non-identical parts in the first phantom and the shapes of the non-identical parts in the second phantom are in a similar relationship. For the sake of simplicity, DIR adjustment will be described below using an example in which the geometric information is information that the shapes of non-identical parts in the first phantom and the shapes of non-identical parts in the second phantom are in a similar relationship. The support device 2 will be explained.

The input unit 24 includes input devices such as a mouse, a keyboard, and a touch panel. The input unit 24 may be configured as an interface that connects these input devices to the own device. The input unit 24 receives, for example, an input of a DIR program to be adjusted. The input unit 24 outputs the input DIR program to be adjusted (hereinafter referred to as “target DIR program”) to the storage unit 23. The input unit 24 receives, for example, an instruction to start adjusting the target DIR program.

The output unit 25 includes a display device such as a CRT (Cathode Ray Tube) display, a liquid crystal display, and an organic EL (Electro-Luminescence) display. The output unit 25 may be configured as an interface that connects these display devices to its own device. The output unit 25 displays information output from the control unit 21. Note that the output unit 25 does not necessarily need to be configured to include a display device, and may be configured to include any device as long as it is capable of outputting information. For example, the output unit 25 may be a sound output device such as a speaker that outputs sound indicating information to be output.

FIG. 2 is a diagram showing an example of the functional configuration of the control unit 21 in the embodiment. More specifically, FIG. 2 shows an example of a functional configuration related to the DIR adjustment process executed by the control unit 21.
The control unit 21 includes a phantom image acquisition unit 211, an original image correspondence information acquisition unit 212, a DIR execution unit 213, a coincidence degree acquisition unit 214, a repetition control unit 215, and a DIR output control unit 216.

The phantom image acquisition unit 211 acquires first phantom image data and second phantom image data via the communication unit 22.

The original image correspondence information acquisition unit 212 acquires information (hereinafter referred to as "original image correspondence information") indicating the correspondence between each position of the image in the first phantom image and each position of the image in the second phantom image. ).

FIG. 3 is a flowchart illustrating an example of a process flow in which the inter-original-image correspondence information acquisition unit 212 acquires the inter-original-image correspondence information in the embodiment.
The original image correspondence information acquisition unit 212 acquires first image position information based on the first physical phantom information and the first phantom on-image position information (step S101). The first image position information is information indicating the positional relationship between each position of the image in the first phantom image and the origin of the first physical phantom coordinate system. Next to step S101, the original image correspondence information acquisition unit 212 acquires second image position information based on the second physical phantom information and the image position information on the second phantom (step S102). The second image position information is information indicating the positional relationship between each position of the image in the second phantom image and the origin of the second physical phantom coordinate system. Next to step S102, the original image correspondence information acquisition unit 212 acquires original image correspondence information based on the geometric information, the irradiation position correspondence information, the first image position information, and the second image position information ( Step S103).

The reason why the inter-original-image correspondence information acquisition unit 212 can acquire the inter-original-image correspondence information through the process shown in FIG. 3 is because there is irradiation position correspondence information. If there is no irradiation position correspondence relationship information, the positional relationship between each position of the image in the first image indicated by the first image position information and each position of the image in the second image indicated by the second image position information is unclear. turn into. In addition, when there is no geometric information, for non-identical parts, each position of the image of the non-identical part in the first phantom image corresponds to which position in the image of the non-identical part in the second phantom image. , is unclear. Precisely because there is geometric information, the original image correspondence information acquisition unit 212 can determine to which position each position of an image of a non-identical part appearing in the first phantom image is located in an image of a non-identical part appearing in the second phantom image. It is possible to obtain highly accurate information indicating whether or not the application is compatible.

The DIR execution unit 213 generates a deformed first phantom image by executing DIR using the target DIR program on the first phantom image. The transformed first phantom image is a first phantom image transformed by DIR of the target DIR program. That is, the deformed first phantom image is the result of executing DIR to be adjusted on the first phantom image.

In addition, by executing DIR, the DIR execution unit 213 generates information (hereinafter referred to as "DIR coordinate correspondence") indicating the correspondence between each position in the first image and each position in the deformed first phantom image. (hereinafter referred to as "DIR coordinate correspondence information"). Since execution of DIR is a process of moving each position in the first image to each position in the deformed first phantom image, the DIR execution unit 213 can acquire DIR coordinate correspondence information. The DIR coordinate correspondence information is, for example, information on a deformation vector field.

FIG. 4 is an explanatory diagram illustrating a deformation vector field in the embodiment.
In FIG. 4, image F1 is an example of an image reflected in the first phantom image. In FIG. 4, image F2 is an example of an image reflected in the second phantom image. FIG. 4 shows that the image F1 and the image F2 have similar shapes, and the image F1 is deformed by DIR so as to approach the shape of the image F2. FIG. 4 shows the deformation vector field when the image F1 is deformed by DIR. The deformation vector field is a set of deformation vectors at each position of the image.

The DIR coordinate correspondence is, for example, an expression matrix representing a mapping from the first coordinate system to the first coordinate system to be transformed, or an inverse matrix thereof.

The matching degree acquisition unit 214 obtains the DIR matching degree based on the original image correspondence information and the DIR coordinate correspondence relationship information. The DIR matching degree is the degree of matching between the deformed first phantom image and the second phantom image.

FIG. 5 is a flowchart illustrating an example of a process flow in which the matching degree acquisition unit 214 acquires the DIR matching degree in the embodiment.
The coincidence degree acquisition unit 214 determines the position of each point on the outline of the non-identical part shown in the first phantom image to be transformed and the non-identical part shown in the second phantom image based on the original image correspondence information and the DIR coordinate correspondence relationship information. Information indicating the correspondence between the positions of each point on the outline of the part (hereinafter referred to as "non-identical part correspondence information") is acquired (step S201). The non-identical part correspondence relationship information is, for example, a deformation that connects a point on the outline of a non-identical part shown in the first phantom image to be transformed and a corresponding point on the outline of the non-identical part shown in the second phantom image. It is a collection of vectors.

Next, the matching degree obtaining unit 214 obtains the DIR matching degree based on the obtained non-identical part correspondence relationship information (step S202). For example, when the non-identical part correspondence relationship information is a set of deformation vectors, the DIR matching degree is the difference between the deformation vector indicated by the inter-original image correspondence information and the deformation vector indicated by the non-identical part correspondence relationship information. The DIR match may be, for example, a target registration error.

The performance of DIR is better as the degree of DIR matching is higher. Therefore, the processing in which the original image correspondence information acquisition unit 212 acquires the original image correspondence information, the DIR execution unit 213 executes DIR, and the coincidence degree acquisition unit 214 acquires the DIR coincidence degree based on the execution result of DIR is performed. , DIR evaluation processing.

The repetition control unit 215 determines whether the DIR coincidence degree acquired by the coincidence degree acquisition unit 214 satisfies the acceptance criteria. The acceptance criterion is, for example, that the degree of DIR matching exceeds a predetermined threshold. If the acceptance criteria are not met, the repetition control unit 215 updates the DIR parameters according to predetermined update rules (hereinafter referred to as "update rules"). The update rule is, for example, a process of reducing the size of the DIR grid. The process in which the repetition control unit 215 updates the DIR parameters according to the update rules is a DIR update process.

After executing the DIR update process, the repetition control unit 215 causes the DIR execution unit 213 to execute DIR for the DIR after the parameter update, and then causes the coincidence degree acquisition unit 214 to evaluate the performance of the DIR after the parameter update. . The DIR adjustment process is a process in which the DIR performance evaluation process and the DIR update process are repeated by the DIR execution unit 213, the coincidence degree acquisition unit 214, and the repetition control unit 215 until the acceptance criteria are met.

The repetition control unit 215 ends the DIR adjustment process when the DIR matching degree satisfies the acceptance criteria.

DIR output control section 216 controls the operation of output section 25. The DIR output control unit 216 controls the operation of the output unit 25 and causes the output unit 25 to output a DIR program that satisfies the acceptance criteria. Further, the DIR output control unit 216 controls the operation of the output unit 25 to cause the output unit 25 to output the DIR matching degree acquired by the matching degree acquisition unit 214.

FIG. 6 is a flowchart showing an example of the flow of processing executed by the DIR adjustment support device 2 of the embodiment.
The phantom image acquisition unit 211 acquires first phantom image data and second phantom image data generated by the imaging unit 1 (step S301). Next, the original image correspondence information acquisition unit 212 acquires the original image correspondence information (step S302). Next, the DIR execution unit 213 executes DIR on the first phantom image to generate a deformed first phantom image (step S303). In the process of step S303, for example, the processes of steps S101 to S103 are executed. Step S303 Next, the matching degree obtaining unit 214 obtains the DIR matching degree based on the correspondence information between original images and the DIR coordinate correspondence relationship information (Step S304). In the process of step S304, for example, the processes of steps S201 to S202 are executed.

Following the process in step S304, the repetition control unit 215 determines whether the DIR matching degree acquired in the immediately previous process satisfies the acceptance criteria (step S305). If the acceptance criteria are not met (step S305: NO), the repetition control unit 215 updates the DIR parameters according to the update rule (step S306). After step S306, the process of step S303 is executed.

On the other hand, if the acceptance criteria are met (step S305: YES), the DIR adjustment process ends, and the DIR output control unit 216 causes the output unit 25 to output the DIR adjusted by the DIR adjustment process (step S307). The DIR that has been adjusted by the DIR adjustment process is the DIR that has been determined to satisfy the acceptance criteria in step S305. Note that the DIR output control unit 216 may cause the output unit 25 to output the history of the DIR matching degree in step S307.

Note that in the flowchart shown in FIG. 6, the DIR evaluation process is the process from step S301 to step S304. The DIR output control unit 216 may cause the output unit 25 to output the DIR coincidence degree every time the process of step S304 is executed.

The DIR adjustment support system 100 of the embodiment configured as described above uses a first physical phantom and a second physical phantom whose shape is partially different from that of the first physical phantom. Evaluate the performance of a certain DIR. Therefore, the effort of the adjuster who is the user of the DIR adjustment support system 100 to judge and instruct the common position between the two images used to evaluate the DIR performance is reduced. . Therefore, the DIR adjustment support system 100 can reduce the effort of the adjuster who adjusts the DIR.

Further, the DIR adjustment support system 100 of the embodiment configured as described above updates the parameters of the DIR based on the evaluation result of the performance of the DIR that is the target of evaluation and the target of adjustment. Therefore, the DIR adjustment support system 100 can reduce the effort of the adjuster who adjusts the DIR.

<About the effect of the first irradiation position and the second irradiation position being located outside the imaging range>
If the first irradiation position and the second irradiation position are located within the imaging range, the first phantom image will include an image indicating the position of the origin of the first phantom coordinate system (hereinafter referred to as the "first origin"). There is. Therefore, when DIR is executed on the first phantom image, the first phantom image is transformed depending on the image indicating the position of the first origin. However, the image indicating the position of the first origin is not an image imitating human tissue. Therefore, the performance of DIR evaluated using a method in which the first origin is included in the first phantom image is approximately the same as the performance of DIR when used in an actual medical setting to examine the affected area using an image that does not include the first origin. This results in performance that is not the same.

On the other hand, in the DIR adjustment support system 100 of the embodiment, the first phantom image does not include an image indicating the position of the first origin. Therefore, the performance of the DIR evaluated in the DIR adjustment support system 100 of the embodiment is substantially the same as the performance of the DIR when used in an actual medical field.

<About physical phantom>
The details of the physical phantom 3 will be explained.
FIG. 7 is a first perspective view showing an example of the physical phantom 3 of the embodiment.
The physical phantom 3 shown in FIG. 7 has substantially the same shape as a rectangular parallelepiped. The physical phantom 3 shown in FIG. 7 is an example of a first physical phantom. Part P1, part P2, part P3, part P4, part P5, and part P6 in FIG. 7 are rectangular parallelepipeds having lengths in the depth direction (Y-axis direction in FIG. 7). Site P1, site P2, site P3, site P4, site P5, and site P6 are removable. Part P1, part P2, part P3, part P4, part P5, and part P6 are three-dimensional shapes that imitate parts of the human body.

The physical phantom 3 shown in FIG. 7 is used to evaluate the performance of DIR as a physical phantom that imitates parts of the human body. The physical phantom 3 shown in FIG. 7 is used, for example, for DIR performance evaluation as a physical phantom imitating the waist of a human body. When the physical phantom 3 in FIG. 7 imitates the waist of a human body, the direction parallel to the Y axis (depth direction) in FIG. 7 is the direction from the feet to the head, and the XZ plane is a plane parallel to the cross section of the waist. be.

FIG. 8 is a diagram showing the parts of the pelvis imitated by part P1, part P2, part P3, and part P5 of the physical phantom 3 of the embodiment shown in FIG.
As shown in FIG. 8, site P1 represents the right femoral head of the pelvis. Site P2 represents the prostate of the pelvis. Site P3 represents the left femoral head of the pelvis. Site P5 represents the rectum of the pelvis. Site P4 and site P6 are soft tissue positions in FIG.

Returning to the explanation of FIG. 7. The physical phantom 3 in FIG. 7 may be used for DIR performance evaluation as a physical phantom that simulates a region other than the waist. For example, the physical phantom 3 may be used to evaluate the performance of DIR as a physical phantom imitating the head and neck. In such a case, site P1 represents the mandible. In such a case, site P2 represents the tumor (tongue). In such a case, site P3 represents the mandible. In such a case, site P5 represents the spinal cord. In such a case, sites P4 and P6 represent the parotid gland.

For example, the physical phantom 3 may be used for DIR performance evaluation as a physical phantom imitating the abdomen. In such a case, site P1 represents the liver. In such a case, site P2 represents the tumor (pancreas). In such a case, site P3 represents the stomach. In such a case, site P5 represents the spinal cord. In such a case, sites P4 and P6 represent the kidneys.
In this way, the parts 4 and 6 are parts that imitate a pair of left and right organs, such as the parotid gland and the kidneys, in the structure of the human body that the physical phantom 3 imitates.

FIG. 9 is a second perspective view showing an example of the physical phantom 3 of the embodiment. More specifically, FIG. 9 shows a physical phantom from which a part of the physical phantom 3 of FIG. 7 has been extracted. In FIG. 9, the extracted portions are region P1, region P2, region P3, region P4, region P5, and region P6 in FIG.

The user can insert into the space after extraction a part that is partially different from the extracted part. For example, the user can insert a solid object that partially differs from the part P1 into the space after the part P1 has been extracted. The solid inserted in place of the part P1 is a solid that represents the shape of the part of the human body represented by the part P1 after it is deformed due to an action such as breathing or a factor such as an illness. Such a physical phantom 3 in which a part that is partially different from the extracted part is inserted into the space after all or part of the parts that can be inserted and removed from the first physical phantom is the same as that of the second physical phantom. This is an example.

FIG. 10 is a diagram showing an example of a cross section of the physical phantom 3 of the embodiment. More specifically, FIG. 10 is a cross-sectional view taken along line AA' of the physical phantom 3 shown in FIG. In parts P1 and P3 of the physical phantom 3, a three-dimensional object whose XZ plane is shaped like a shuriken is embedded. The three-dimensional object whose XZ plane (that is, cross section) is shaped like a shuriken is, for example, a three-dimensional object imitating human bones. In the center of the XZ plane of the part P2 of the physical phantom 3, a solid T1 whose XZ plane has a triangular shape is embedded. The solid T1 whose XZ plane is triangular in shape is, for example, a solid that imitates the prostate of a human body. The material of the solid body T1 is, for example, acrylic.

The part P2 of the physical phantom 3 has a plurality of dots around the triangular solid T1. The dot body is a solid whose size in the XZ plane is smaller than a predetermined size. Hereinafter, a figure representing the outline of a cross section (ie, XZ plane) of a dot body will be referred to as a dot. For example, in FIG. 10, four dots are arranged at the vertices of a rectangle on each of the left and right sides of a triangular solid T1. In FIG. 10, the eight dot bodies in total are dot body D1, dot body D2, dot body D3, dot body D4, dot body D5, dot body D6, dot body D7, and dot body D8. The left and right sides of the triangular solid T1 refer to positions in the positive direction and negative direction in the X-axis direction with the center of gravity of the triangular solid T1 on the XZ plane as the center. The shape, size, number, and position of the dots have a smaller influence on the conversion by DIR than a predetermined influence. The dots may be of any shape as long as the size, number, and position have a smaller effect on the DIR conversion than a predetermined effect. For example, the shape of the dots may be a circle, an ellipse, or a star.

<About the effects of dots>
It is known that in DIR, which attempts to match only the triangular solid T1 with a predetermined precision or higher accuracy before and after DIR conversion, the periphery of the solid T1 deforms more greatly than other parts. Since the physical phantom 3 shown in FIG. 10 has dot bodies D1 to D8 around the solid body T1, when evaluating the performance of DIR using the physical phantom 3 shown in FIG. The performance of DIR is also evaluated based on the amount of deformation. Therefore, the results of DIR performance evaluation using Physical Phantom 3, which has multiple solids with dot cross sections around solid T1, are more reliable than the results of DIR performance evaluation using only solid T1. .

FIG. 10 shows that part P5 has a space V1 whose XZ plane has a trapezoidal shape. In FIG. 10, the space V1 is filled with vacuum or air. For example, a dosimeter may be installed inside the space V1. In such a case, the user can also know changes in the dose distribution due to the DIR to be evaluated using the physical phantom 3.

At the position where the region P2 is inserted, the user can insert another solid body whose shape or size is different from the shape or size of the triangular solid T1 shown in FIG. Therefore, the physical phantom 3 into which such another solid is inserted is a physical phantom that differs from the physical phantom 3 of FIG. 10 only in the triangular solid T1. In such a case, the solid T1 shown in FIG. 10 is an example of a changed part, and the parts other than the solid T1 among the parts of the physical phantom 3 shown in FIG. 10 are examples of changed parts.

FIG. 11 is a diagram showing an example of the shape of the physical phantom 3 in the depth direction of the embodiment. More specifically, FIG. 11 is a cross-sectional view taken along line BB' of the physical phantom 3 shown in FIG. FIG. 11 shows that the shape of the three-dimensional object embedded in the removable portion does not necessarily have to be uniform in the depth direction. For example, in FIG. 11, the portion P5 has a rectangular parallelepiped shape, and the space V1 that the portion P5 has does not have a uniform shape in the Y-axis direction (that is, the depth direction). The three-dimensional shape embedded in the removable portion may be uniform in the depth direction.

Note that the physical phantom 3 in FIG. 7 does not necessarily have to have a plurality of parts that can be inserted and removed, and may be one.

(Modified example)
Note that the first phantom on-image position information and the second phantom on-image position information do not need to be stored in the storage unit 23 in advance. The first phantom on-image position information and the second phantom on-image position information may be input by the user via the input unit 24, for example. For example, the user may view the first phantom image, visually determine the position of the image represented by the first phantom image on the first physical phantom, and input the determination result to the DIR adjustment support device 2. For example, the user may view the second phantom image, visually determine the position of the image shown by the second phantom image on the second physical phantom, and input the determination result to the DIR adjustment support device 2.

When such a user visually determines the position of the image shown by the first phantom image on the first physical phantom and the position of the image shown by the first phantom image on the first physical phantom, the laser light source 11 is not necessary. In such a case, the irradiation position correspondence relationship information does not necessarily include the positional relationship between the first irradiation position and other anatomical matching parts of the first physical phantom, and the positional relationship between the second irradiation position and other anatomical matching parts of the second physical phantom. The information does not have to be information indicating that the positional relationship with the anatomical matching site is the same.

As described above, the first irradiation position is the position of the origin of the first physical phantom coordinate system. Therefore, when the laser light source 11 is not provided, the user may instruct the DIR adjustment support device 2 via the input unit 24, for example, as to the position on the physical phantom corresponding to the origin of the first physical phantom coordinate system. Hereinafter, information indicating the position on the physical phantom corresponding to the origin of the first physical phantom coordinate system will be referred to as first origin position information. Further, if the laser light source 11 is not provided, the position on the physical phantom corresponding to the origin of the first physical phantom coordinate system may be specified by the user to the DIR adjustment support device 2 via the input unit 24, for example. . Hereinafter, information indicating the position on the physical phantom corresponding to the origin of the second physical phantom coordinate system will be referred to as second origin position information.

In this case, the irradiation position correspondence relationship information includes the positional relationship between the position indicated by the first origin position information and other anatomically matching parts of the first physical phantom, and the position indicated by the second origin position information and the second physical phantom. Information indicating that the positional relationship with other anatomically matching parts is the same is stored.

Note that the DIR adjustment support system 100 does not necessarily need to include the repetition control unit 215, and may not necessarily include the repetition control unit 215. In such a case, the DIR adjustment support system 100 evaluates the performance of the DIR to be evaluated, but does not adjust the parameters of the DIR based on the evaluation result. That is, such a DIR adjustment support system 100 executes a DIR evaluation process but does not execute a DIR update process.

The DIR adjustment support system 100 that does not perform such DIR update processing cannot reduce the amount of labor required by the adjuster as much as the case where the DIR adjustment support system 100 does not perform such DIR update processing. However, even in the DIR adjustment support system 100 that does not perform such a DIR update process, evaluation can be performed using a non-first physical phantom and a second physical phantom whose shape is partially different from the first physical phantom. The performance of DIR, which is the target and adjustment target, is evaluated. Therefore, the effort of the adjuster, who is a user of the DIR adjustment support system 100, is reduced in determining and instructing a common position between two images used to evaluate DIR performance. In this way, even with the DIR adjustment support system 100 that does not perform DIR update processing, the effort of the adjuster who adjusts the DIR can be reduced.

Note that the contour of the first physical phantom image used when the DIR adjustment support system 100 obtains the DIR coincidence degree and the contour of the second physical phantom image reflected in the second phantom image are not necessarily similar to each other as shown in FIG. It does not need to be in the shape of That is, the geometric information does not necessarily have to be information that the shapes of the non-identical parts in the first phantom and the shapes of the non-identical parts in the second phantom are in a similar relationship. The first physical phantom image is the first physical phantom that appears in the first phantom image. The second physical phantom image is a second physical phantom that appears in the second phantom image. For example, the shape of the first physical phantom image is a shape that satisfies the axiomatic system of Euclidean geometry, and the shape of the second physical phantom image is a shape that satisfies the axiomatic system of non-Euclidean geometry, and that satisfies the axiomatic system of Euclidean geometry. It may be a shape that does not satisfy the requirements. For example, the first physical phantom image used when obtaining the DIR matching degree is a triangle shown in FIG. 4, and the outline of the second physical phantom image used when obtaining the DIR matching degree is the shape F3 shown below. It may be. In such a case, the geometric information may be, for example, information indicating the geometric relationship between the triangle and the shape F3.

FIG. 12 is a diagram showing an example of a shape that satisfies the axiomatic system of non-Euclidean geometry but does not satisfy the axiomatic system of Euclidean geometry. The shape F3 in FIG. 12 is a shape that satisfies the axiomatic system of non-Euclidean geometry, but does not satisfy the axiomatic system of Euclidean geometry. The shape F3 has a vertex C1, a vertex C2, and a vertex C3, and the sum of the angle θ1 at the vertex C1, the angle θ2 at the vertex C2, and the angle θ3 at the vertex C3 exceeds 180°.

Note that the geometric information may be, for example, information that the shape of a non-identical part in the first phantom and the shape of a non-identical part in the second phantom are in a relationship of expansion or contraction.

FIG. 13 is a diagram illustrating an example of an image appearing in a first phantom image and an example of an image appearing in a second phantom image in a relationship of enlargement or reduction in a modified example.
Image F1 in FIG. 13 is an image reflected in the first phantom image. In FIG. 13, the image F1 is a triangle. In FIG. 13, image F2 is an image reflected in the second phantom image. In FIG. 13, image F2 is a triangle. In FIG. 13, the image F1 and the image F2 are in an enlarged or reduced relationship. More specifically, the triangle of image F2 is a diagram obtained by reducing the height of the triangle of image F1 in FIG.

Note that the second physical phantom does not need to be one in which the three-dimensional objects of the first physical phantom that can be inserted and removed are changed to other three-dimensional objects, and may be formed entirely of a material different from that of the first physical phantom. .

Note that the DIR matching degree is an example of information indicating the degree of matching between the DIR execution result and the second image. The first phantom image is an example of a first image. The second phantom image is an example of a second image. The DIR adjustment support device 2 is an example of a non-rigid image registration adjustment support device. The repetition control unit 215 is an example of a DIR update unit. The first phantom image and the second phantom image are examples of imaging results.

The DIR adjustment support device 2 may be implemented using a plurality of information processing devices communicably connected via a network. In this case, each functional unit included in the DIR adjustment support device 2 may be distributed and implemented in a plurality of information processing devices. For example, the repetition control unit 215 may be implemented in an information processing device different from other functional units included in the control unit 21.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and includes designs within the scope of the gist of the present invention.

100... DIR adjustment support system, 1... Imaging unit, 11... Laser light source, 12... Imaging device, 2... DIR adjustment support device, 21... Control unit, 22... Communication unit, 23... Storage unit, 24... Input unit, 25 ...Output unit, 211...Phantom image acquisition unit, 212...Original image correspondence information acquisition unit, 213...DIR execution unit, 214...Concordance degree acquisition unit, 215...Repetition control unit, 216...DIR output control unit, 3...Physics phantom

Claims (10)

a DIR execution unit that executes non-rigid image registration (DIR: Deformable Image Registration) on a first image that is a photographing result of a first physical phantom that is a physical phantom that imitates part or all of a human body;
First physical phantom information, which is information indicating the shape and size of the first physical phantom, and information indicating the shape and size of a second physical phantom, which is a physical phantom having a partially different shape from the first physical phantom. second physical phantom information that is information showing the image, first phantom image position information that is information showing the position of the image shown by the first image on the first physical phantom, and a photographing result of the second physical phantom. Image position information on a second phantom, which is information indicating the position of an image shown by a certain second image on the second physical phantom, and image position information on a second phantom that is a part of the first physical phantom and has a different shape from the second physical phantom. Geometry that is information indicating a relationship between a polygonal shape of an image of a region and a polygonal shape of an image of a region that is part of the second physical phantom and has a different shape from the first physical phantom; acquisition of a degree of coincidence, which is information indicating the degree of coincidence between the DIR execution result by the DIR execution unit and the second image that is the photographed result of the second physical phantom, based on the scientific information; Department and
a repetition control unit that determines whether or not the acceptance criteria are met based on whether or not the DIR matching degree exceeds a predetermined threshold;
Equipped with
By executing the DIR, the correspondence between each position in the first image and each position in the deformed first image generated by executing the DIR is set as DIR coordinate correspondence relationship information,
The correspondence between each position of the image in the first image and each position of the image in the second image is set as inter-original image correspondence information,
Based on the original image correspondence information and the DIR coordinate correspondence relationship information, the position of each point on the contour of the non-identical part shown in the first image to be transformed and the position of each point on the contour of the non-identical part shown in the second image is determined. When the correspondence between the positions of each point is treated as non-identical part correspondence information,
The DIR matching degree is the difference between the deformation vector indicated by the original image correspondence information and the deformation vector indicated by the non-identical part correspondence information,
the number of vertices of the polygon that is part of the first physical phantom and has a different shape from the second physical phantom; and the number of vertices of the polygon that is part of the second physical phantom and has a different shape from the first physical phantom. The number of vertices of a polygon is the same,
Non-rigid image registration adjustment support device. The geometric information includes a first image (F1) of a part of the first physical phantom that is different in shape from the second physical phantom , and a first image (F1) of a part of the second physical phantom that is part of the second physical phantom. 1. A second image (F2) that applies to a part whose shape is different from that of the physical phantom ; and a deformation vector field that is a set of the deformation vectors at each position of the image. It shows that there is a relationship of similar shapes that are transformed so as to approach
The non-rigid image registration adjustment support device according to claim 1. The geometric information includes a first image (F1) of a part of the first physical phantom that is different in shape from the second physical phantom , and a first image (F1) of a part of the second physical phantom that is part of the second physical phantom. 1. A second image (F2) that covers a part having a different shape from that of the physical phantom , and a deformation vector field that is a set of the deformation vectors at each position of the image are used to enlarge or reduce the height of the first image. Indicates that the shape is deformed so as to approximate the shape of the second image ;
The non-rigid image registration adjustment support device according to claim 1. a DIR updating unit that updates the DIR based on the degree acquired by the coincidence degree acquisition unit;
The non-rigid image registration adjustment support device according to any one of claims 1 to 3 , further comprising: The physical phantom has one or more parts that can be inserted and removed,
The non-rigid image registration adjustment support device according to any one of claims 1 to 4 . Some or all of the removable and removable parts have a solid shape, size, number, and position that have a smaller influence on DIR than a predetermined influence;
The non-rigid image registration adjustment support device according to claim 5 . The physical phantom is a physical phantom that imitates the waist of a human body.
The non-rigid image registration adjustment support device according to any one of claims 1 to 6 . The second physical phantom has a plurality of dot bodies each of which is a three-dimensional part in which the size of the figure to be imaged is smaller than a predetermined size.
The non-rigid image registration adjustment support device according to any one of claims 1 to 7. a DIR execution step of performing non-rigid image registration (DIR: Deformable Image Registration) on a first image that is a photographing result of a first physical phantom that is a physical phantom that imitates part or all of a human body;
First physical phantom information, which is information indicating the shape and size of the first physical phantom, and information indicating the shape and size of a second physical phantom, which is a physical phantom having a partially different shape from the first physical phantom. second physical phantom information that is information showing the image, first phantom image position information that is information showing the position of the image shown by the first image on the first physical phantom, and a photographing result of the second physical phantom. Image position information on a second phantom, which is information indicating the position of an image shown by a certain second image on the second physical phantom, and image position information on a second phantom that is a part of the first physical phantom and has a different shape from the second physical phantom. Geometry that is information indicating a relationship between a polygonal shape of an image of a region and a polygonal shape of an image of a region that is part of the second physical phantom and has a different shape from the first physical phantom; acquisition of a degree of coincidence, which is information indicating the degree of coincidence between the DIR execution result in the DIR execution step and the second image that is the photographing result of the second physical phantom, based on the scientific information; step and
a repetitive control step of determining whether or not the acceptance criteria are met based on whether or not the degree of DIR coincidence exceeds a predetermined threshold;
has
By executing the DIR, the correspondence between each position in the first image and each position in the deformed first image generated by executing the DIR is set as DIR coordinate correspondence relationship information,
The correspondence between each position of the image in the first image and each position of the image in the second image is set as inter-original image correspondence information,
Based on the original image correspondence information and the DIR coordinate correspondence relationship information, the position of each point on the contour of the non-identical part shown in the first image to be transformed and the position of each point on the contour of the non-identical part shown in the second image is determined. When the correspondence between the positions of each point is treated as non-identical part correspondence information,
The DIR matching degree is the difference between the deformation vector indicated by the original image correspondence information and the deformation vector indicated by the non-identical part correspondence information,
the number of vertices of the polygon that is part of the first physical phantom and has a different shape from the second physical phantom; and the number of vertices of the polygon that is part of the second physical phantom and has a different shape from the first physical phantom. The number of vertices of a polygon is the same,
Non-rigid image registration adjustment support method. A program for causing a computer to function as the non-rigid image registration adjustment support device according to claim 1.

Images