Medical image processing device, treatment system, medical image processing method, program, and storage medium

Abstract

A medical image processing device according to an embodiment comprises: a first image acquisition unit that acquires a first image, which is a three-dimensional fluoroscopic image of a patient captured at a first stage; a second image acquisition unit that acquires a second image, which is a three-dimensional fluoroscopic image of the patient captured in a second stage that is subsequent to the first stage; a 3D-3D positioning execution unit that executes 3D-3D positioning for calculating a first deviation amount between the first image and the second image; a DRR image generation unit that generates a two-dimensional first DRR image from the first image and generates a two-dimensional second DRR image from the second image corrected on the basis of the first deviation amount; and a display control unit that causes a display device to display the first DRR image and the second DRR image.

Description

Medical image processing device, treatment system, medical image processing method, program, and recording medium

[0001] Embodiments of the present invention relate to a medical image processing apparatus, a treatment system, a medical image processing method, a program, and a recording medium. This application claims priority under Japanese Patent Application No. 2024-193947, filed in Japan on November 5, 2024, the contents of which are incorporated herein by reference.

[0002] Radiation therapy is a treatment method that destroys lesions in a patient's body by irradiating them with radiation. In this process, the radiation must be precisely directed to the location of the lesion. This is because irradiating healthy tissue within the patient's body can affect that tissue as well. Therefore, during the treatment planning stage of radiation therapy, the location of the lesion in the patient's body is determined in three dimensions. To achieve this, a three-dimensional fluoroscopic image of the patient is taken. A CT image obtained by computed tomography (CT) is an example of a three-dimensional fluoroscopic image. Based on the determined location of the lesion, the direction and intensity of radiation are planned to minimize irradiation of healthy tissue. Then, during the actual treatment phase, the patient's position is adjusted to match the position determined during the treatment planning stage, and radiation is delivered to the lesion according to the planned direction and intensity.

[0003] During patient positioning in the treatment phase, a three-dimensional fluoroscopic image is virtually placed in the treatment room, and the position of the mobile treatment table is adjusted so that the actual position of the patient lying on the table matches the position of the three-dimensional fluoroscopic image. More specifically, the patient's positional shift between the two images is determined by comparing (3D-3D positioning) the three-dimensional fluoroscopic image taken during treatment planning and the three-dimensional fluoroscopic image of the patient lying on the table. Based on the positional shift determined by image comparison, the table is moved to match the position of lesions and bones within the patient's body to the position during treatment planning. After that, the radiation therapist (such as a doctor) approves the positioning by visually comparing the captured images, and then irradiates the lesion with radiation.

[0004] Japanese Patent Publication No. 2018-507073

[0005] When a radiation therapist (such as a doctor) visually compares three-dimensional fluoroscopic images, it is necessary to check each of the plurality of cross-sectional images of the three-dimensional fluoroscopic image one by one. For this reason, it has taken time to check. Since the patient has to be kept waiting during the image check, the burden on the patient has also increased.

[0006] The present invention has been made in consideration of such circumstances, and an object thereof is to provide a medical image processing apparatus, a treatment system, a medical image processing method, a program, and a recording medium that facilitate confirmation of positioning.

[0007] The medical image processing apparatus according to the embodiment includes a first image acquisition unit that acquires a first image that is a three-dimensional fluoroscopic image of a patient taken in a first stage, and the patient taken in a second stage after the first stage. A second image acquisition unit that acquires a second image that is a three-dimensional fluoroscopic image of the patient, a 3D-3D positioning execution unit that executes 3D-3D positioning for calculating a first displacement amount between the first image and the second image, and the first A DRR image generation unit that generates a two-dimensional first DRR image from the image and generates a two-dimensional second DRR image from the second image corrected based on the first displacement amount, and the first DRR image and the second DRR image are displayed on a display device. And a display control unit.

[0008] According to an embodiment of the present invention, it is possible to provide a medical image processing apparatus, a treatment system, a medical image processing method, a program, and a recording medium that facilitate confirmation of positioning.

[0009] A block diagram showing the schematic configuration of a treatment system equipped with the medical image processing device of the first embodiment. A block diagram showing the schematic configuration of the treatment system equipped with the medical image processing device of the first embodiment, viewed from a different angle than Figure 1. A block diagram mainly showing the schematic configuration of the medical image processing device of the first embodiment. A flowchart showing an example of the processing flow performed by the medical image processing device of the first embodiment. A block diagram mainly showing the schematic configuration of a modified medical image processing device of the first embodiment. A block diagram mainly showing the schematic configuration of the medical image processing device of the second embodiment. A diagram showing an example of a superimposed image generated by the DRR image superimposition unit of the medical image processing device of the second embodiment. A flowchart showing an example of the processing flow performed by the medical image processing device of the second embodiment.

[0010] (First Embodiment) Hereinafter, a medical image processing apparatus, treatment system, medical image processing method, program, and recording medium of the first embodiment will be described with reference to the drawings.

[0011] [Overall Configuration] Figure 1 is a block diagram showing the schematic configuration of a treatment system 1 equipped with a medical image processing device 100 of an embodiment. The treatment system 1 includes, for example, a treatment device 10, a medical image processing device 100, and a display device 200. The treatment device 10 includes, for example, a patient bed 12, a patient bed control unit 14, a treatment beam irradiation gate 18 (irradiation unit), and a first imaging device D1. In Figure 1, a computed tomography (CT) device 16 (hereinafter referred to as "CT imaging device 16") is shown as an example of the first imaging device D1.

[0012] The treatment table 12 is a movable treatment table that fixes a patient P (subject) receiving radiation therapy in a lying position, for example, using a restraint device. The treatment table 12 moves with the patient P fixed inside the annular CT scanner 16 having an opening, according to the control from the treatment table control unit 14. The treatment table control unit 14 controls the translational mechanism and rotational mechanism provided on the treatment table 12 in order to position the patient P fixed to the treatment table 12 according to the movement amount signal output by the medical image processing device 100. The translational mechanism can drive the treatment table 12 in three axial directions (X axis, Y axis, Z axis). The rotational mechanism can rotate the treatment table 12 around three axes. In other words, the treatment table control unit 14 moves the treatment table 12 with six degrees of freedom by controlling, for example, the translational mechanism and rotational mechanism of the treatment table 12. The bed control unit 14 has six degrees of freedom to control the bed 12, but may have fewer than six degrees of freedom (for example, four degrees of freedom) or more than six degrees of freedom (for example, eight degrees of freedom). The bed 12 is installed so as to be movable to both positions when the position where imaging by the CT scanner 16 is performed and the position where the treatment beam B is irradiated by the treatment beam irradiation gate 18 are different.

[0013] The CT scanner 16 performs three-dimensional computed tomography. The CT scanner 16 has multiple radiation sources arranged inside the annular (gantry) opening. Each of the multiple radiation sources emits radiation to visualize the inside of the patient P's body. In other words, the CT scanner 16 emits radiation from multiple locations around the patient P. In the CT scanner 16, the radiation emitted from each of the multiple radiation sources is, for example, X-rays. The CT scanner 16 has multiple radiation detectors arranged inside the annular opening. Each of the multiple radiation detectors detects radiation emitted from the corresponding radiation source and that has passed through the patient P's body. The CT scanner 16 generates a CT image of the inside of the patient P's body based on the magnitude of the radiation energy detected by each of the multiple radiation detectors. The CT image of patient P generated by the CT scanner 16 is a three-dimensional digital image. The three-dimensional digital image represents the magnitude of the degree of radiation attenuation at each of the multiple locations inside the body as a digital value. The CT scanner 16 outputs the generated CT image to the medical image processing device 100. The imaging of the inside of the patient P's body in the CT scanner 16, that is, the generation of a CT image based on the irradiation of radiation from each of the multiple radiation sources and the radiation detected by each of the multiple radiation detectors, is controlled, for example, by an imaging control unit (not shown).

[0014] The treatment beam irradiation gate 18 irradiates the patient P with radiation as treatment beam B to destroy the tumor (lesion), which is the target area for treatment, located within the patient P's body. Treatment beam B can be, for example, X-rays, gamma rays, electron beams, proton beams, neutron beams, or heavy ion beams. Treatment beam B is irradiated linearly from the treatment beam irradiation gate 18 to the patient P (more specifically, the tumor inside the patient P's body). The irradiation of treatment beam B at the treatment beam irradiation gate 18 is controlled, for example, by a treatment beam irradiation control unit (not shown). In the illustrated treatment system 1, the treatment beam irradiation gate 18 is an example of an "irradiation unit". A rotating gantry that can irradiate the patient P with treatment beam B from any irradiation direction may be used as the irradiation unit.

[0015] In radiation therapy, the irradiation direction and intensity of the treatment beam B are planned by simulating the patient P being placed on the treatment table 12 in the treatment room. This stage of planning the treatment is called the "treatment planning stage." The treatment planning stage is an example of the "first stage." After the first stage, the second stage is performed. Here, the "second stage" is a concept that includes not only the period during which the treatment beam B is actually irradiated to the patient P, but also the period immediately before and after that.

[0016] In the treatment planning stage, specifically, the physician identifies the area to be irradiated using a CT image (an example of the "first image") and determines the irradiation dose and the irradiation angle of the treatment beam. For this reason, the CT image in the treatment planning stage is accompanied by information related to the treatment plan (hereinafter referred to as supplementary information or treatment planning information), such as parameters representing the angle of the treatment table 12 in the treatment room and the position of the patient P (lying on their back or on their stomach). The supplementary information may also include information such as the location of the tumor and the location of organs at risk that should be avoided from radiation exposure. The supplementary information may also include parameters assigned to each pixel of the CT image for coloring the location of the tumor, the location of organs at risk, etc. The CT image taken inside the patient P's body by the CT scanner 16 does not have supplementary information attached. Therefore, supplementary information may be added to the CT image taken inside the patient P's body by the CT scanner 16 by comparing it with a CT image that has supplementary information, such as the CT image in the treatment planning stage. For example, the pixel values ​​of the tumor image region in a CT image with supplementary information may be used as a reference, and compared with the pixel values ​​of a CT image without supplementary information. The location where the difference in pixel values ​​is small may be considered the tumor location in the CT image without supplementary information. This process may be performed not only on tumors but also on organs at risk.

[0017] The treatment plan will be explained in detail. The treatment plan determines the energy of the treatment beam B (radiation) to be irradiated to patient P, the direction of irradiation, the shape of the irradiation area, and the distribution of doses when the treatment beam B is irradiated in multiple sessions. More specifically, first, the person who plans the treatment (such as a doctor) specifies the boundary between the tumor (lesion) area and the area of ​​normal tissue, and the boundary between the tumor and surrounding important organs, etc., for the first image taken during the treatment planning stage (for example, a CT image taken by a CT scanner 16). Then, the treatment plan determines the direction (path through which the treatment beam B passes) and intensity of the irradiation of the treatment beam B, based on the depth from the surface of patient P to the location of the tumor and the size of the tumor, which are calculated from the tumor information specified by the person who plans the treatment (such as a doctor). In addition, a marker may be implanted inside patient P's body by percutaneous procedure. In this case, the position of the marker implanted inside patient P is also registered in the treatment plan.

[0018] Figure 1 shows a CT scanner 16 as an example of the first imaging device D1. However, the first imaging device D1 can be any device that generates three-dimensional images of the inside of the patient P's body, such as a cone-beam (CB) CT scanner, a magnetic resonance imaging (MRI) scanner, or an ultrasound diagnostic device.

[0019] In the second stage, the medical image processing device 100 outputs a movement amount signal to the bed control unit 14 to move the bed 12 in order to position the patient P in the same position as in the treatment planning stage. In other words, the medical image processing device 100 outputs a movement amount signal to the bed control unit 14 to move the patient P so that the treatment beam B can be appropriately irradiated to the tumor or tissue to be treated in radiotherapy. The movement amount signal is determined based on the first displacement amount and the second displacement amount, etc., which will be described later.

[0020] In the second stage, the display device 200 displays images to present various information in the treatment system 1 to the radiation therapist (such as a doctor) using the treatment system 1, including information obtained during the patient P positioning process in the medical image processing device 100. The display device 200 displays various images, such as CT images and X-ray fluoroscopy images output by the medical image processing device 100, or images on which various information is superimposed. Here, various information includes, for example, patient information (age, sex, height, weight, etc.), image acquisition conditions (acquisition site, presence or absence of contrast agent, tube voltage, tube current, etc.), date and time of acquisition, or patient position (head supine, feet prone, etc.). The display device 200 includes, for example, a device such as a liquid crystal display (LCD). The radiation therapist can obtain information for performing radiation therapy using the treatment system 1 by visually confirming the images displayed on the display device 200. The treatment system 1 may be configured to include a user interface, such as an operating unit (not shown), which is operated by the person performing the radiation therapy, and to allow manual operation of various functions performed by the treatment system 1.

[0021] Figure 2 is a schematic diagram of the treatment system 1, viewed from a different angle than Figure 1. Figure 2 is a block diagram showing the schematic configuration of the treatment system. As shown in Figure 2, the treatment system 1 includes a second imaging device D2. The second imaging device D2 has, for example, two radiation sources 20 (radiation source 20-1 and radiation source 20-2) and two radiation detectors 30 (radiation detector 30-1 and radiation detector 30-2). However, the second imaging device D2 may be, for example, an ultrasound diagnostic device.

[0022] Radiation source 20-1 irradiates patient P with radiation r-1 at a predetermined angle for fluoroscopy of the patient's body. Radiation source 20-2 irradiates patient P with radiation r-2 at a predetermined angle different from that of radiation source 20-1 for fluoroscopy of the patient's body. Radiation sources 20-1 and 20-2 are, for example, X-ray sources, and radiation r-1 and radiation r-2 are, for example, X-rays. Figure 2 shows a case where X-ray imaging is performed from two directions on patient P fixed on a bed 12. Note that in Figure 2, the control unit that controls the irradiation of radiation r-1 and r-2 by radiation source 20 is omitted. In the following description, radiation r-1 and r-2 may be simply referred to as radiation r.

[0023] Radiation detector 30-1 detects radiation r-1 that has been irradiated from radiation source 20-1 and passed through the body of patient P, and generates an X-ray fluoroscopic image of the inside of patient P corresponding to the energy magnitude of the detected radiation r-1. Radiation detector 30-2 detects radiation r-2 that has been irradiated from radiation source 20-2 and passed through the body of patient P, and generates an X-ray fluoroscopic image of the inside of patient P corresponding to the energy magnitude of the detected radiation r-2. In radiation detector 30, multiple X-ray detectors are arranged in a two-dimensional array. Radiation detector 30 generates a digital image as an X-ray fluoroscopic image, representing the energy magnitude of the radiation r that has reached each of the multiple X-ray detectors as a digital value.

[0024] The radiation detector 30 is, for example, a flat panel detector (FPD), an image intensifier, or a color image intensifier. The following describes the case where each of the multiple radiation detectors 30 is an FPD. Each radiation detector 30 (FPD) outputs the generated X-ray fluoroscopic image to the medical image processing device 100. Note that in Figure 2, the control unit that controls the generation of X-ray fluoroscopic images by the radiation detectors 30 is omitted from the diagram.

[0025] The specific configuration of the second imaging device D2 may be changed. For example, the second imaging device D2 may be equipped with three or more sets of radiation sources 20 and radiation detectors 30. Alternatively, the second imaging device D2 may be equipped with only one set of radiation sources 20 and radiation detectors 30. Hereinafter, the combination of radiation sources 20 and radiation detectors 30 may be referred to as an "X-ray imaging device".

[0026] The various components shown in Figures 1 and 2 may be connected to each other by wires, or they may be connected wirelessly, for example, by a LAN (Local Area Network) or a WAN (Wide Area Network).

[0027] [Medical Image Processing Device] The medical image processing device 100 of the embodiment will be described below. Figure 3 is a block diagram mainly showing the schematic configuration of the medical image processing device 100 of the embodiment. The medical image processing device 100 includes, for example, a first image acquisition unit 110, a second image acquisition unit 120, a 3D-3D positioning execution unit 130, a DRR image generation unit 140, a comparison unit 150, and a display control unit 170.

[0028] Some or all of the components of the medical image processing device 100 are realized, for example, by a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Some or all of these components may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or GPU (Graphics Processing Unit), or by the cooperation of software and hardware. Some or all of the functions of these components may be realized by a dedicated LSI. The program may be stored in advance in a storage device (a storage device equipped with a non-transient recording medium) such as ROM (Read Only Memory), RAM (Random Access Memory), HDD (Hard Disk Drive), or flash memory provided by the medical image processing device 100. The program may also be stored in a removable recording medium (a non-transient recording medium) such as a DVD or CD-ROM, and installed in the HDD or flash memory of the medical image processing device 100 when the recording medium is inserted into the drive device provided by the medical image processing device 100. The program may also be downloaded from another computer device via a network and installed in the HDD or flash memory of the medical image processing device 100.

[0029] The first image acquisition unit 110 acquires a first image of patient P during the treatment planning stage (first stage). The first image is a three-dimensional CT image representing the three-dimensional shape of the patient P's body, which is taken, for example, by a CT scanner 16 during the treatment planning stage. The first image is used to determine the direction (path including inclination and distance, etc.) and intensity of the treatment beam B irradiated onto patient P during radiation therapy. The first image may also be an MRI image taken by an MRI scanner during the treatment planning stage.

[0030] The second image acquisition unit 120 acquires a second image of patient P immediately before the start of radiation therapy (i.e., the second stage). The second image is a three-dimensional CT image representing the three-dimensional shape of the inside of patient P's body, taken, for example, by a CT scanner 16, in order to adjust the position of patient P when irradiating with the treatment beam B during radiation therapy (i.e., positioning). In other words, the second image is an image taken by the CT scanner 16 immediately before irradiating with the treatment beam B from the treatment beam irradiation gate 18. In this case, the time at which the first image is acquired and the time at which the second image is acquired are different, but the method of acquiring the first image is the same as the method of acquiring the second image. The second image may also be an MRI image acquired by an MRI scanner in the second stage.

[0031] The 3D-3D positioning execution unit 130 performs 3D-3D positioning processing to align the position of patient P when performing radiation therapy, based on the first image acquired by the first image acquisition unit 110 and the second image acquired by the second image acquisition unit 120. More specifically, for example, the medical image processing device 100 calculates the amount of three-dimensional displacement (hereinafter sometimes referred to as the "first displacement amount") between the first image acquired by the first image acquisition unit 110 and the second image acquired by the second image acquisition unit 120, and aligns the position between the first image and the second image by correcting the second image by the calculated first displacement amount.

[0032] In the second stage, the medical image processing device 100 may output a movement amount signal to the bed control unit 14 to move the bed 12 on which the patient P is placed and fixed by a first displacement amount, and the bed control unit 14 may move the bed 12 by the first displacement amount. Also, if the CT scanning device 16 and the treatment beam irradiation gate 18 are installed at separate locations, the medical image processing device 100 may output a movement amount signal to the bed control unit 14 to move the bed 12 by the distance between the CT scanning position and the irradiation position plus the first displacement amount. The bed control unit 14 may move the bed 12 by the distance between the CT scanning position and the irradiation position plus the first displacement amount.

[0033] The DRR image generation unit 140 generates a first DRR image from the first image and generates a second DRR image from the second image, which has been corrected by a first displacement amount. A DRR (Digitally Reconstructed Radiograph) image is a digitally reconstructed X-ray photograph obtained by virtually reconstructing an X-ray fluoroscopic image from a three-dimensional image (for example, a CT image). The method for creating DRR images in the DRR image generation unit 140 is described below. In an X-ray imaging device, an internal fluoroscopic image is obtained by converting the energy of X-rays emitted from an X-ray source (radiation source 20) through the patient's body and reaching an FPD (radiation detector 30) into pixel values. To simulate this, an X-ray source and an FPD are placed in a virtual three-dimensional space, and the patient's CT images (first image, second image) are placed between the X-ray source and the FPD. The energy attenuation of X-rays from the X-ray source to each pixel position of the FPD is determined by the material in the X-ray path. For example, if there is a CT image in the X-ray path, the energy attenuation is calculated according to the pixel values ​​of the CT image at the points the X-ray passes through.

[0034] The DRR image generation unit 140 can generate a DRR image viewed from a specific direction based on a three-dimensional CT image. For example, the DRR image generation unit 140 may generate a first DRR image and a second DRR image viewed from the irradiation direction of the treatment beam B. In this case, the position of the X-ray source necessary for generating the DRR image is set at the exit port of the treatment beam B, and the position of the FPD is set at an arbitrary position on the back of the patient P. When generating the first DRR image and the second DRR image, an X-ray source and an FPD placed at the same position in a virtual three-dimensional space are used. The FPD here can be a virtual FPD. Therefore, it is not necessary to limit it to the FPD of the second imaging device D2. For example, the size or number of detectors placed on the FPD can be set arbitrarily. In other words, the resolution and image size of the first DRR image and the second DRR image can be set arbitrarily. In other words, as the first and second DRR images, DRR images with increased resolution may be created only in the region near the path of treatment beam B. Furthermore, the placement of the first and second images can also be limited to the region near the tumor.

[0035] Furthermore, the DRR image generation unit 140 can generate a DRR image that emphasizes a specific part of patient P by creating a DRR image that emphasizes a specific CT value in the three-dimensional CT image. For example, the DRR image generation unit 140 may generate a DRR image that emphasizes the bone area of ​​patient P by creating a DRR image that emphasizes the CT value corresponding to the bone area in the three-dimensional CT image. The DRR image generation unit 140 may also generate a DRR image that emphasizes the tissue of the lesion in patient P that is of importance, or the tissue that the radiation therapist (such as a doctor) wants to focus on. In addition, the DRR image generation unit 140 can generate a DRR image that extracts a specific range in the three-dimensional CT image. For example, the DRR image generation unit 140 may generate a DRR image that extracts the range from the surface of patient P's body to the location of the tumor (the range to which the treatment beam B is irradiated) within patient P's body.

[0036] The comparison unit 150 compares the first DRR image and the second DRR image generated by the DRR image generation unit 140. For example, the comparison unit 150 calculates the difference in pixel values ​​between pixels at the same position in the first DRR image and the second DRR image.

[0037] The display control unit 170 displays various information processed by the medical image processing device 100 on the display device 200. Specifically, the display control unit 170 displays the first DRR image and the second DRR image generated by the DRR image generation unit 140 on the display device 200. At this time, the display control unit 170 may display the first DRR image and the second DRR image side by side on the display device 200. The display control unit 170 may also display the first DRR image and the second DRR image alternately in space on the display device 200. More specifically, the display control unit 170 may divide the first DRR image into a plurality of first divided images, divide the second DRR image into a plurality of second divided images, and display the first divided images and the second divided images alternately in a grid pattern on the display device 200. The display control unit 170 may also display the comparison results from the comparison unit 150 on the display device 200. For example, the display control unit 170 may display a difference image obtained by taking the difference between the first DRR image and the second DRR image on the display device. Alternatively, the display control unit 170 may display the result of the 3D-3D positioning process on the display device 200.

[0038] The radiation therapist (such as a physician) confirms the positioning by visually comparing the first DRR image and the second DRR image displayed on the display device 200. In this embodiment, since the radiation therapist visually compares the two-dimensional first DRR image and the two-dimensional second DRR image, confirming the positioning becomes easier compared to visually comparing three-dimensional fluoroscopic images. Furthermore, the time required for confirmation can be reduced, thereby reducing the burden on the patient.

[0039] Next, with reference to Figure 4, the processing flow performed by the medical image processing device 100 will be described. Figure 4 is a flowchart showing an example of the processing flow performed by the medical image processing device 100.

[0040] First, the first image acquisition unit 110 acquires a three-dimensional fluoroscopic image (e.g., a CT image) that has been taken in advance during the treatment planning stage as the first image (step S100). Next, the medical image processing device 100 moves the bed 12 on which the patient P is fixed to a position where it can be photographed by the first imaging device D1 (e.g., a CT scanner 16) (step S102). Specifically, the medical image processing device 100 outputs a movement amount signal to the bed control unit 14. The bed control unit 14 controls the translation mechanism and the like provided on the bed 12. Next, the first imaging device D1 takes a three-dimensional fluoroscopic image (e.g., a CT image) of the patient P, and the second image acquisition unit 120 acquires the captured three-dimensional fluoroscopic image as the second image (step S104).

[0041] Next, the 3D-3D positioning execution unit 130 performs 3D-3D positioning processing based on the first image acquired by the first image acquisition unit 110 and the second image acquired by the second image acquisition unit 120, and calculates the first displacement amount (step S106). Next, the bed control unit 14 moves the bed 12 by the first displacement amount determined by the 3D-3D positioning processing (step S108).

[0042] Next, the DRR image generation unit 140 generates a first DRR image from the first image and generates a second DRR image from the second image corrected by a first displacement amount (step S110). The comparison unit 150 compares the first DRR image and the second DRR image generated by the DRR image generation unit 140 (step S112). The display control unit 170 displays the first DRR image and the second DRR image generated by the DRR image generation unit 140, as well as the comparison results from the comparison unit 150, on the display device 200 (step S114). The radiation therapist approves the positioning by visually comparing and confirming the first DRR image and the second DRR image displayed on the display device 200.

[0043] In the process of the flowchart shown in FIG. 4, in step S108, the bed control unit 14 moves the bed 12 by the amount of the first deviation specified by the 3D-3D positioning process. However, the process of step S108 may be omitted. When the CT imaging device 16 and the treatment beam irradiation door 18 are installed at positions far from each other, the process of step S108 may be a process of moving the bed 12 by adding the amount of the first deviation to the distance between the CT imaging position and the irradiation position.

[0044] As described above, the medical image processing apparatus 100 according to the present embodiment includes a first image acquisition unit 110 that acquires a first image, which is a three-dimensional fluoroscopic image of the patient P taken in the first stage, a second image acquisition unit 120 that acquires a second image, which is a three-dimensional fluoroscopic image of the patient P taken in a second stage after the first stage, a 3D-3D positioning execution unit 130 that executes 3D-3D positioning for calculating the amount of the first deviation between the first image and the second image, a DRR image generation unit 140 that generates a two-dimensional first DRR image from the first image and generates a two-dimensional second DRR image from the second image corrected based on the amount of the first deviation, and a display control unit 170 that causes the display device 200 to display the first DRR image and the second DRR image. According to the above configuration, an operator (such as a doctor) of radiotherapy can confirm the positioning by visually comparing the two-dimensional first DRR image and the two-dimensional second DRR image. Therefore, it becomes easier to confirm the positioning.

[0045] The medical image processing apparatus 100 may further include a comparison unit 150 that compares the first DRR image and the second DRR image, and the display control unit 170 may cause the display device 200 to display the comparison result by the comparison unit 150. The comparison unit 150 calculates the difference in pixel values between the first DRR image and the second DRR image, and the display control unit 170 may cause the display device 200 to display the difference image between the first DRR image and the second DRR image. According to the above configuration, it becomes even easier to confirm the positioning.

[0046] The DRR image generation unit 140 may generate a first DRR image and a second DRR image as viewed from the irradiation direction of the treatment beam B irradiated to the patient P. According to the above configuration, the practitioner of radiotherapy can visually compare the first DRR image and the second DRR image as viewed from the irradiation direction of the treatment beam B irradiated to the patient P, making it easier to confirm the positioning. Regarding the fluoroscopic X-ray image of the patient P taken by the second imaging device D2, the possible imaging directions are limited. That is, since it is necessary to prevent the irradiation direction of the X-rays irradiated from the second imaging device D2 from overlapping with the irradiation direction of the treatment beam B, it is not possible to take a fluoroscopic X-ray image as viewed from the irradiation direction of the treatment beam B. Since the DRR image generation unit 140 has no such restrictions as described above, it can generate the first DRR image and the second DRR image as viewed from the irradiation direction of the treatment beam B.

[0047] Further, the display control unit 170 may cause the display device 200 to display the first DRR image and the second DRR image alternately in space. According to the above configuration, it becomes easier to confirm the positioning.

[0048] (Modification of the First Embodiment) Hereinafter, a modification of the first embodiment will be described with reference to FIG. 5. As shown in FIG. 5, the medical image processing apparatus 100 may further include a 3D-2D positioning execution unit 160. The 3D-2D positioning execution unit 160 performs 3D-2D positioning processing for collating a DRR image for positioning (hereinafter, may be referred to as the "third DRR image") generated from the first image with a fluoroscopic X-ray image, which is a two-dimensional fluoroscopic image of the patient P taken by the second imaging device D2 in the second stage. Further, the display control unit 170 may cause the display device 200 to display the execution result of the 3D-2D positioning processing.

[0049] This section describes the method for creating DRR images in the 3D-2D positioning execution unit 160. In an X-ray imaging device, X-rays emitted from an X-ray source (radiation source 20) pass through the patient's body and, upon reaching the FPD (radiation detector 30), their energy is converted into pixel values ​​to obtain a fluoroscopic image of the body. To simulate this, an X-ray source and FPD are placed in the same positions as the X-ray imaging device in a virtual three-dimensional space, and a CT image of the patient is placed between the X-ray source and the FPD. The amount of energy attenuation of X-rays from the X-ray source to each pixel position of the FPD is determined by the material in the path of the X-rays. For example, if there is a CT image in the path of the X-rays, the amount of energy attenuation is calculated according to the pixel values ​​of the CT image at the positions the X-rays pass through.

[0050] The 3D-2D positioning execution unit 160 calculates the amount of three-dimensional displacement (hereinafter sometimes referred to as the "second displacement") between the third DRR image generated from the first image and the X-ray fluoroscopic image of patient P taken after moving the bed 12 on which patient P is placed and fixed by a first displacement amount. The radiation therapist approves the positioning if, for example, the calculated second displacement is less than a threshold. On the other hand, if the calculated second displacement is greater than or equal to the threshold, the bed control unit 14 moves the bed 12 by the calculated second displacement amount, takes another X-ray fluoroscopic image of patient P, and the 3D-2D positioning execution unit 160 performs the 3D-2D positioning process again using the captured X-ray fluoroscopic image. The above process is repeated until the positioning is finally approved by the radiation therapist. The positioning DRR image (third DRR image) may be a DRR image generated from the second image corrected by the first displacement amount.

[0051] Furthermore, in this modified example, in the processing performed by the medical image processing device 100, a 3D-2D positioning process may be performed after step S108. In this case, the 3D-2D positioning execution unit 160 performs a 3D-2D positioning process based on the third DRR image generated from the first image and the X-ray fluoroscopic image of patient P taken by the second imaging device D2 in the second stage, and calculates the second displacement amount. Next, the medical image processing device 100 determines whether the positioning has been approved by the radiation therapist. More specifically, the medical image processing device 100 may determine whether the positioning has been manually approved by the radiation therapist via an interface on the display device 200. The medical image processing device 100 may also automatically determine whether the positioning has been approved by determining whether the second displacement amount is within a threshold. If it is determined that the positioning has been approved, the medical image processing device 100 confirms the positioning and proceeds to step S110. On the other hand, if approval is not determined, the bed control unit 14 moves the bed 12 by the second displacement amount identified by the 3D-2D positioning process and performs the 3D-2D positioning process again. The third DRR image in the 3D-2D positioning execution unit 160 may be a third DRR image generated from the second image. The second displacement amount obtained at this time is used to confirm whether there has been any change in the position of patient P since the second image was taken. Thus, the third DRR image may be a DRR image generated from the first image and the second image, and the second displacement amount may be determined for each.

[0052] As described above, the medical image processing device 100 may further include a 3D-2D positioning execution unit 160 that performs 3D-2D positioning to calculate a second displacement amount between a third DRR image generated from a first image or a second image corrected based on a first displacement amount and a two-dimensional fluoroscopic image of patient P.

[0053] (Second Embodiment) The second embodiment will now be described. The configuration of the treatment system equipped with the medical image processing device of the second embodiment is the same as the configuration of the treatment system 1 equipped with the medical image processing device 100 of the first embodiment shown in Figure 1, but in which the medical image processing device 100 is replaced with the medical image processing device of the second embodiment (hereinafter referred to as "medical image processing device 100A"). In the following description, the treatment system equipped with the medical image processing device 100A will be referred to as "treatment system 1A".

[0054] In the following description, components of the treatment system 1A equipped with the medical image processing device 100A that are the same as those of the treatment system 1 equipped with the medical image processing device 100 of the first embodiment will be given the same reference numerals, and detailed descriptions of each component will be omitted. Furthermore, in the following description, only the configuration, operation, and processing of the medical image processing device 100A, which are components that differ from the medical image processing device 100 of the first embodiment, will be described.

[0055] The configuration of the medical image processing device 100A will be described below. Figure 6 is a block diagram showing an example of the configuration of the medical image processing device 100A according to the second embodiment. The medical image processing device 100A includes a first image acquisition unit 110, a second image acquisition unit 120, a 3D-3D positioning execution unit 130, a DRR image generation unit 140, a comparison unit 150, and a display control unit 170, as well as a region information acquisition unit 210, a region estimation unit 220, and a DRR image superposition unit 230.

[0056] The region information acquisition unit 210 acquires region information corresponding to a predetermined region of the first image. Region information is information from the treatment plan information (ancillary information) that is associated with a predetermined region of the first image. For example, region information may include the location of a tumor (contour information), the location of a risk organ (contour information), or the irradiation direction and irradiation area of ​​the treatment beam B (path of the treatment beam B). If a marker is implanted in the patient P's body, the region information may also be the location (contour information) of the implanted marker. For example, if the region information is the location of a tumor, the region information is associated with pixels, etc., in the region corresponding to the tumor in the first image. The region information may also be stored together with the first image on a recording medium provided by the medical image processing device 100A. In this case, the region information acquisition unit 210 reads the region information from the recording medium.

[0057] The region estimation unit 220 estimates the region in the second image that corresponds to the region information, based on the first image and the region information. For example, if the region information is the location of a tumor, the region estimation unit 220 estimates the extent of the tumor in the second image as the region. For example, if the region information is the location of a marker, the region estimation unit 220 estimates the extent of the marker in the second image as the region. The estimation method is not limited, but for example, the region (location of the tumor) in the second image may be estimated based on the positional relationship between a specific bone and the tumor in the first image and the position of the specific bone in the second image.

[0058] The DRR image superposition unit 230 generates a superimposed image by superimposing region information onto the first DRR image and the second DRR image, based on region information and regions estimated by the region estimation unit 220. Figure 7 shows an example of a superimposed image generated by the DRR image superposition unit 230. As shown in Figure 7(a), the first DRR image has a tumor region A1 indicating the location of the tumor, a passage region A2 indicating the path of the treatment beam B, and a risk region A3 indicating the location of a risk organ superimposed on it. As shown in Figure 7(b), the second DRR image has a tumor region A1' indicating the location of the tumor, a passage region A2' indicating the path of the treatment beam B, and a risk region A3' indicating the location of a risk organ superimposed on it, as estimated by the region estimation unit 220.

[0059] Furthermore, in this embodiment, the comparison unit 150 compares the first DRR image and the second DRR image based on the superimposed image generated by the DRR image superimposition unit 230. For example, the comparison unit 150 may calculate the degree of overlap or misalignment between the region superimposed on the first DRR image (e.g., tumor region A1) and the region superimposed on the second DRR image (e.g., tumor region A1').

[0060] Furthermore, in this embodiment, the 3D-3D positioning execution unit 130 may acquire region information and region information estimated by the region estimation unit 220, and calculate the amount of displacement of the center of gravity of the tumor in three-dimensional space between the first image and the second image. If a marker is implanted in the patient P's body, the 3D-3D positioning execution unit 130 may calculate the amount of displacement of the center of gravity of the marker in three-dimensional space. The 3D-3D positioning execution unit 130 may calculate the length of the path of the treatment beam B in the first image and the second image, respectively, and calculate the difference in the length of the path of the treatment beam B between the first image and the second image.

[0061] The display control unit 170 displays the superimposed image generated by the DRR image superimposition unit 230 on the display device 200. The display control unit 170 may also display the degree of overlap or misalignment calculated by the comparison unit 150 on the display device 200. The display control unit 170 may also display the amount of displacement of the center of gravity of the tumor or marker in three-dimensional space, or the difference in the length of the path of the treatment beam B, calculated by the 3D-3D positioning execution unit 130, on the display device 200.

[0062] Next, with reference to Figure 8, the processing flow performed by the medical image processing device 100A will be described. Figure 8 is a flowchart showing an example of the processing flow performed by the medical image processing device 100A. Steps S100, S102, S104, S106, S108, and S110 are the same as the processing performed by the medical image processing device 100 of the first embodiment, so their description is omitted here.

[0063] In this embodiment, step S200 is performed after step S110. In step S200, the region information acquisition unit 210 acquires region information corresponding to a predetermined region of the first image. Next, the region estimation unit 220 estimates the region in the second image corresponding to the region information based on the first image and the region information (step S202). The DRR image superposition unit 230 generates a superimposed image by superimposing the region information onto the first DRR image and the second DRR image based on the region information and the region estimated by the region estimation unit 220 (step S204). The comparison unit 150 compares the first DRR image and the second DRR image based on the superimposed image generated by the DRR image superposition unit 230 (step S206). The display control unit 170 displays the superimposed image generated by the DRR image superposition unit 230 and the comparison result by the comparison unit 150 on the display device 200 (step S208). The radiation therapist approves the positioning by visually comparing and confirming the superimposed images (first DRR image and second DRR image) displayed on the display device 200.

[0064] As described above, the medical image processing apparatus 100A of this embodiment further comprises: a region information acquisition unit 210 that acquires region information corresponding to a region of a first image; a region estimation unit 220 that estimates a region in a second image that corresponds to the region information; and a DRR image superposition unit 230 that generates a superimposed image by superimposing region information onto the first DRR image and the second DRR image based on the region information and the region estimated by the region estimation unit 220. The display control unit 170 causes the superimposed image to be displayed on the display device 200. With the above configuration, position confirmation becomes easier.

[0065] Furthermore, the comparison unit 150 may calculate the degree of overlap or misalignment between the region superimposed on the first DRR image and the region superimposed on the second DRR image in the superimposed image, and the display control unit 170 may display the calculated degree of overlap or misalignment on the display device 200. With the above configuration, positioning can be confirmed more easily.

[0066] The region estimated by the region estimation unit 220 may be the extent of the tumor in the second image. The region estimated by the region estimation unit 220 may also be the extent of the marker in the second image.

[0067] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0068] 1, 1A... Treatment system 10... Treatment device 12... Treatment table 14... Treatment table control unit 100, 100A... Medical image processing device 110... First image acquisition unit 120... Second image acquisition unit 130... 3D-3D positioning execution unit 140... DRR image generation unit 150... Comparison unit 160... 3D-2D positioning execution unit 170... Display control unit 200... Display device 210... Region information acquisition unit 220... Region estimation unit 230... DRR image superposition unit

Claims

1. A medical image processing apparatus comprising: a first image acquisition unit that acquires a first image, which is a three-dimensional fluoroscopic image of a patient taken in a first stage; a second image acquisition unit that acquires a second image, which is a three-dimensional fluoroscopic image of the patient taken in a second stage that is later than the first stage; a 3D-3D positioning execution unit that performs 3D-3D positioning to calculate a first displacement amount between the first image and the second image; a DRR image generation unit that generates a two-dimensional first DRR image from the first image and generates a two-dimensional second DRR image from the second image corrected based on the first displacement amount; and a display control unit that displays the first DRR image and the second DRR image on a display device.

2. The medical image processing apparatus according to claim 1, further comprising a comparison unit for comparing the first DRR image with the second DRR image, wherein the display control unit causes the comparison result by the comparison unit to be displayed on the display device.

3. A medical image processing apparatus according to claim 1, further comprising: a region information acquisition unit that acquires region information corresponding to a region of the first image; a region estimation unit that estimates a region in the second image corresponding to the region information; and a DRR image superposition unit that generates a superimposed image by superimposing the region information onto the first DRR image and the second DRR image based on the region information and the region estimated by the region estimation unit, wherein the display control unit causes the superimposed image to be displayed on the display device.

4. The medical image processing apparatus according to claim 1, wherein the DRR image generation unit generates the first DRR image and the second DRR image as viewed from the irradiation direction of the treatment beam irradiated onto the patient.

5. A medical image processing apparatus according to claim 3, further comprising a comparison unit for comparing the first DRR image and the second DRR image, wherein the comparison unit calculates the degree of overlap or misalignment between the region superimposed on the first DRR image and the region superimposed on the second DRR image in the superimposed image, and the display control unit causes the calculated degree of overlap or misalignment to be displayed on the display device.

6. The medical image processing apparatus according to claim 2, wherein the comparison unit calculates the difference in pixel values ​​between the first DRR image and the second DRR image, and the display control unit causes the display device to display the difference image between the first DRR image and the second DRR image.

7. The medical image processing apparatus according to claim 1, wherein the display control unit causes the first DRR image and the second DRR image to be displayed spatially alternately on the display device.

8. The medical image processing apparatus according to claim 3, wherein the region estimated by the region estimation unit is the extent of the tumor in the second image.

9. The medical image processing apparatus according to claim 3, wherein the region estimated by the region estimation unit is the range of the marker in the second image.

10. The medical image processing apparatus according to claim 1, further comprising: a 3D-2D positioning execution unit that performs 3D-2D positioning for calculating a second displacement amount between a third DRR image generated from the first image or the second image corrected based on the first displacement amount and a two-dimensional fluoroscopic image of the patient.

11. A treatment system comprising: a medical image processing device according to any one of claims 1 to 10; an irradiation unit for irradiating the patient with radiation; a first imaging device for capturing the second image; a bed for placing and fixing the patient; and a bed control unit for controlling the movement of the bed.

12. A medical image processing method comprising: a computer acquiring a first image, which is a three-dimensional fluoroscopic image of a patient taken in a first stage; acquiring a second image, which is a three-dimensional fluoroscopic image of the patient taken in a second stage after the first stage; performing 3D-3D positioning to calculate a first displacement amount between the first image and the second image; generating a two-dimensional first DRR image from the first image; generating a two-dimensional second DRR image from the second image corrected based on the first displacement amount; and displaying the first DRR image and the second DRR image on a display device.

13. A program that causes a computer to acquire a first image, which is a three-dimensional fluoroscopic image of the patient taken in the first stage; acquire a second image, which is a three-dimensional fluoroscopic image of the patient taken in the second stage, which is after the first stage; perform 3D-3D positioning to calculate a first displacement amount between the first image and the second image; generate a two-dimensional first DRR image from the first image; generate a two-dimensional second DRR image from the second image corrected based on the first displacement amount; and display the first DRR image and the second DRR image on a display device.

14. A recording medium on which a program is recorded, wherein the program causes a computer to acquire a first image, which is a three-dimensional fluoroscopic image of a patient taken in a first stage; acquire a second image, which is a three-dimensional fluoroscopic image of the patient taken in a second stage after the first stage; perform 3D-3D positioning to calculate a first displacement amount between the first image and the second image; generate a two-dimensional first DRR image from the first image; generate a two-dimensional second DRR image from the second image corrected based on the first displacement amount; and display the first DRR image and the second DRR image on a display device.

Images