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

Abstract

To provide a medical image processing apparatus, a treatment system, a medical image processing method, a program and a storage medium which can perform quantitative confirmation of a positioning result of a patient performed with image collation of a transparent image.SOLUTION: A medical image processing apparatus according to an embodiment comprises: a first image acquisition unit; a second image acquisition unit; a treatment error acquisition unit; a difference calculation unit; and a difference statistical amount calculation unit. The first image acquisition unit acquires a first transparent image obtained by imaging the interior of the body of a patient. The second image acquisition unit acquires a second transparent image of the interior of the body of the patient imaged at a different time from the first transparent image. The treatment error acquisition unit acquires a treatment error generated when executing positioning processing or in a treatment. The difference calculation unit calculates a difference image between the second transparent image and the first transparent image by giving a virtual disturbance to the position of the patient imaged based on the treatment error. The difference statistical amount calculation unit calculates a statistical amount of the difference between the first transparent image and the second transparent image based on the difference image.SELECTED DRAWING: Figure 2

Description

Technical Field

[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 storage medium.

Background Art

[0002] Radiation therapy is a treatment method that destroys a tumor by irradiating radiation to the tumor (lesion) in a patient's body. Since radiation may affect normal tissues when irradiated to normal tissues in the patient's body, in radiation therapy, it is necessary to accurately irradiate radiation to the position of the tumor. For this reason, when performing radiation therapy, first, at the treatment planning stage, for example, computed tomography (CT) is performed in advance, and the position of the tumor in the patient's body is grasped three-dimensionally. Then, based on the grasped position of the tumor, the direction of irradiation of radiation and the intensity of the irradiated radiation are planned. Thereafter, at the treatment stage, the position of the patient is adjusted to the position of the patient at the treatment planning stage, and radiation is irradiated to the tumor according to the irradiation direction and irradiation intensity planned at the treatment planning stage.

[0003] In the patient positioning at the treatment stage, image matching is performed between a fluoroscopic image of the patient's body taken in a state where the patient is lying on a bed immediately before starting treatment and a digitally reconstructed radiograph (DRR) image obtained by virtually reconstructing a fluoroscopic image from a three-dimensional CT image taken at the treatment planning stage, and the displacement of the patient's position between the respective images is obtained. Then, by moving the bed based on the obtained displacement, the positions of the tumor, bone, etc. in the patient's body are aligned with those at the treatment planning stage.

[0004] The patient's positional displacement is determined by searching for the patient's position in the CT image so that the DRR image most similar to the fluoroscopic image is reconstructed. Numerous methods have been proposed to automate the search for the patient's position using computers. However, conventional methods required users (such as doctors) to verify the results of the automated search by comparing the fluoroscopic image and the DRR image. For example, conventional methods involved making the fluoroscopic image and the DRR image semi-transparent and overlaying them, allowing the user to visually confirm whether the contours of the bone edges matched. However, this verification method does not quantify the degree of matching of the patient's position. Therefore, with a method that relies on visual verification by the user, there was a possibility that the effectiveness of the treatment performed could vary depending on the skill of the user performing the verification.

[0005] Incidentally, it was sometimes difficult to visually confirm the location of a tumor as seen in a fluoroscopic image. This is because tumors are more transparent to X-rays than bones, and therefore do not appear clearly in fluoroscopic images. In recent years, however, CT images have been taken instead of fluoroscopic images to confirm the location of the tumor during treatment. In this case, the displacement of the patient's position is determined by comparing the CT images taken during treatment planning with the CT images taken during the treatment stage; in other words, by comparing the CT images themselves.

[0006] In image matching between CT images, the position of one CT image is shifted, and the position that most closely resembles that of the other CT image is found. One possible method for image matching between CT images is to compare the pixel values ​​of the two CT images and search for the position with the smallest difference. Furthermore, as an example of another method for image matching between CT images, one could use the CT image to calculate the amount of energy loss when radiation passes through the human body (CT data) and find the position where this matches. In this case, the degree of agreement in the amount of energy loss is quantitative, so it does not need to be left to the user's judgment, and it may be possible to mechanically determine whether or not the patient's positioning has been successful.

[0007] On the other hand, if CT images can be taken during treatment, it will become possible to replan the treatment plan to accommodate changes in the patient's condition (such as changes in posture) as treatment progresses. For example, it will be possible to change the treatment plan based on the differences between two CT images. In this case, it will be necessary to present the differences between the two CT images to the user. For example, the amount of change in the patient's position that matches through alignment will be presented to the user. However, in patient alignment during the treatment stage, the patient's position is adjusted by physically moving the treatment table on which the patient lies. Therefore, there was a possibility of errors occurring that would not appear in calculated alignment based on image data, such as image matching between CT images, such as errors in the movement of the treatment table. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] U.S. Patent Application Publication No. 2011 / 0058750 [Patent Document 2] Japanese Patent Publication No. 2020-127723 [Patent Document 3] Japanese Patent Publication No. 2021-137323 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The problem that the present invention aims to solve is to provide a medical image processing device, a treatment system, a medical image processing method, a program, and a storage medium that can quantitatively confirm the results of patient positioning performed by image matching of fluoroscopic images. [Means for solving the problem]

[0010] The medical image processing apparatus of the embodiment includes a first image acquisition unit, a second image acquisition unit, a treatment error acquisition unit, a difference calculation unit, and a difference statistics calculation unit. The first image acquisition unit acquires a first fluoroscopic image taken inside the patient's body. The second image acquisition unit acquires a second fluoroscopic image taken inside the patient's body at a different time than the first fluoroscopic image. The treatment error acquisition unit acquires treatment errors that occur when performing alignment processing to match the position of the patient as depicted in the second fluoroscopic image to the position of the patient as depicted in the first fluoroscopic image, based on the first and second fluoroscopic images, or when treatment errors occur. The difference calculation unit calculates the position of the patient as depicted in the second fluoroscopic image based on the treatment errors. and change the parameters that represent posture virtual misalignment Give, the above misalignment The difference image between the second perspective image and the first perspective image is calculated based on the difference image. misalignment The difference statistics between the given second perspective image and the given image are calculated. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a medical image processing device, a treatment system, a medical image processing method, a program, and a storage medium that can quantitatively confirm the results of patient positioning by image matching between CT images taken during treatment planning and during the treatment phase. [Brief explanation of the drawing]

[0012] [Figure 1] A block diagram showing the schematic configuration of a treatment system equipped with a medical image processing device according to the first embodiment. [Figure 2] A block diagram showing the general configuration of a medical image processing device. [Figure 3] A flowchart illustrating the process for outputting differential statistics in a medical image processing system. [Figure 4] A block diagram showing the schematic configuration of the medical image processing device according to the second embodiment. [Figure 5]A flowchart showing the process of determining whether adjustment of a patient's position is necessary in a medical image processing device. [Figure 6] A block diagram showing the schematic configuration of a medical image processing device according to a third embodiment. [Figure 7] A diagram showing an example of presentation data generated by a presentation data processing unit included in a medical image processing device. [Figure 8] A diagram showing an example of a display screen on which a presentation data processing unit included in a medical image processing device displays presentation data on a display device. [Figure 9] A diagram showing an example of another display screen on which a presentation data processing unit included in a medical image processing device displays presentation data on a display device.

Mode for Carrying Out the Invention

[0013] Hereinafter, a medical image processing device, a treatment system, a medical image processing method, a program, and a storage medium according to an embodiment will be described with reference to the drawings.

[0014] (First Embodiment) FIG. 1 is a block diagram showing the schematic configuration of a treatment system including a medical image processing device according to the first embodiment. The treatment system 1 includes, for example, a treatment device 10 and a medical image processing device 100. The treatment device 10 includes, for example, a hospital bed 12, a computed tomography (CT) device 14 (hereinafter referred to as "CT imaging device 14"), and a treatment beam irradiation door 16.

[0015] The treatment table 12 is a movable treatment table that fixes a subject (patient) P 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 14 having an opening, according to control from the medical image processing device 100. The medical image processing device 100 outputs movement control signals to control the translation and rotation mechanisms provided on the treatment table 12 in order to change the direction in which the treatment beam B is irradiated onto the patient P fixed on the treatment table 12. The translation mechanism can drive the treatment table 12 in three axial directions, and the rotation mechanism can drive the treatment table 12 around three axes. Therefore, the medical image processing device 100 moves the treatment table 12 with six degrees of freedom by controlling the translation and rotation mechanisms of the treatment table 12, for example. The degrees of freedom with which the medical image processing device 100 controls the patient bed 12 do not have to be six degrees of freedom; they may be 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).

[0016] The CT imaging device 14 is an imaging device for performing three-dimensional computed tomography. In the CT imaging device 14, a plurality of radiation sources are arranged inside an annular opening, and radiation for fluoroscoping the inside of the patient P is irradiated from each radiation source. That is, the CT imaging device 14 irradiates radiation from a plurality of positions around the patient P. The radiation irradiated from each radiation source in the CT imaging device 14 is, for example, X-rays. The CT imaging device 14 detects the radiation that has been irradiated from the corresponding radiation source, passed through the inside of the patient P, and reached, by means of a plurality of radiation detectors arranged inside the annular opening. The CT imaging device 14 generates a CT image of the inside of the patient P based on the magnitude of the energy of the radiation detected by each radiation detector. The CT image of the patient P generated by the CT imaging device 14 is a three-dimensional digital image representing the magnitude of the energy of the radiation as digital values. The CT imaging device 14 outputs the generated CT image to the medical image processing device 100. The three-dimensional imaging of the inside of the patient P in the CT imaging device 14, that is, the irradiation of radiation from each radiation source and the generation of the CT image based on the radiation detected by each radiation detector, are controlled by, for example, an imaging control unit (not shown). The CT imaging device 14 is an example of an "imaging device".

[0017] The treatment beam irradiation port 16 irradiates radiation for destroying a tumor (lesion), which is a treatment target site existing inside the patient P, as a treatment beam B. The treatment beam B is, for example, X-rays, γ-rays, electron beams, proton beams, neutron beams, heavy particle beams, or the like. The treatment beam B is irradiated linearly from the treatment beam irradiation port 16 to the patient P (more specifically, the tumor inside the patient P). The irradiation of the treatment beam B at the treatment beam irradiation port 16 is controlled by, for example, a treatment beam irradiation control unit (not shown). The treatment beam irradiation port 16 is an example of an "irradiation unit".

[0018] In the treatment room where the treatment system 1 is installed, a three-dimensional coordinate system of a reference position is pre-set as shown in Figure 1. In the treatment room where the treatment beam B is irradiated onto patient P, the installation position of the treatment beam irradiation gate 16, the direction of irradiation of the treatment beam B (irradiation direction), the installation position of the treatment table 12, the installation position of the CT scanner 14, and the location from which CT images of the inside of patient P are taken are all determined according to the pre-set three-dimensional coordinate system of the reference position. In the following explanation, the three-dimensional coordinate system of the reference position pre-set in the treatment room is defined as the "room coordinate system." In the following explanation, "position" refers to the three-axis (three-dimensional) coordinates of the treatment table 12 as determined by the translation mechanism, as expressed according to the room coordinate system, and "posture" refers to the rotation angle around the three axes, as determined by the rotation mechanism of the treatment table 12, as expressed according to the room coordinate system. For example, the position of the bed 12 is the position of a predetermined point included in the bed 12, expressed in three-dimensional coordinates, and the posture of the bed 12 is the rotation angle of the bed 12 expressed in terms of yaw, roll, and pitch.

[0019] In radiation therapy, treatment plans are developed in a simulated treatment room environment. Specifically, the direction and intensity of the treatment beam B are planned by simulating the patient P's position on the treatment table 12 in the treatment room. Therefore, CT images taken during the treatment planning stage (treatment planning stage) are imprinted with information such as parameters representing the position and orientation of the treatment table 12 within the treatment room. This is also true for CT images taken immediately before radiation therapy and for CT images taken during previous radiation therapy sessions. In other words, CT images taken inside the patient P's body by the CT scanner 14 are imprinted with parameters representing the position and orientation of the treatment table 12 at the time of the scan.

[0020] Figure 1 shows the configuration of a treatment device 10 comprising a CT scanner 14 and a fixed treatment beam irradiation gate 16, but the configuration of the treatment device 10 is not limited to the above configuration. For example, the treatment device 10 may be configured to include, instead of the CT scanner 14, an imaging device that generates three-dimensional images of the inside of the patient P, such as a CT scanner in which a set of radiation sources and radiation detectors rotate inside an annular opening, a cone-beam (CB) CT scanner, a magnetic resonance imaging (MRI) scanner, or an ultrasound diagnostic device. For example, the treatment device 10 may be configured to include multiple treatment beam irradiation gates, such as further including a treatment beam irradiation gate that irradiates the patient P with a treatment beam from a horizontal direction. For example, the treatment device 10 may be configured to irradiate the patient P with a treatment beam from various directions by rotating around the patient P, such as by having the single treatment beam irradiation gate 16 shown in Figure 1 rotate 360 ​​degrees around the rotation axis in the horizontal direction X shown in Figure 1. For example, the treatment device 10 may, instead of the CT scanner 14, include one or more imaging devices consisting of a radiation source and a radiation detector, and this imaging device may rotate 360 ​​degrees around the rotation axis in the horizontal direction X shown in Figure 1, thereby imaging the inside of the patient P's body from various directions. Such a configuration is called a rotating gantry type treatment device. In this case, for example, one treatment beam irradiation gate 16 shown in Figure 1 may rotate simultaneously with the imaging device on the same rotation axis.

[0021] The medical image processing device 100 performs processing to align the position of patient P when performing radiation therapy, based on the CT images output by the CT scanner 14. More specifically, the medical image processing device 100 performs processing to align the position of tumors and tissues present in patient P's body, based on, for example, the CT image of patient P taken before radiation therapy, such as during the treatment planning stage, and the current CT image of patient P taken by the CT scanner 14 during the treatment stage (treatment stage) in which radiation therapy is performed. The medical image processing device 100 then outputs a movement control signal to move the patient bed 12 to align the irradiation direction of the treatment beam B emitted from the treatment beam irradiation gate 16 with the direction set during the treatment planning stage. In other words, the medical image processing device 100 moves patient P in a direction that allows the treatment beam B to appropriately irradiate the tumors and tissues to be treated during radiation therapy, based on the movement control signal.

[0022] The medical image processing device 100 and the CT scanning device 14 provided in the treatment device 10 may be connected by a wire, or they may be connected wirelessly, for example, by a LAN (Local Area Network) or WAN (Wide Area Network).

[0023] Furthermore, the medical image processing device 100 presents information representing the result (or even the in-progress) of the process for aligning the patient P's position (hereinafter referred to as "positioning process") to the person performing the radiation therapy, such as a physician, i.e., the user of the treatment system 1. Figure 1 shows a configuration in which the medical image processing device 100 presents the result of the positioning process to the user (hereinafter referred to as "user") by displaying images and information on a display device D, such as a liquid crystal display (LCD), an organic electroluminescence (EL) display, or a micro-LED (light-emitting diode) display. The display device D may be, for example, a display device connected to a personal computer (PC) (a so-called PC monitor), or a display device installed in a terminal device (digital device) such as a tablet or smartphone. This allows the user to check the result of the positioning process displayed on the display device D and decide whether to end the positioning process, i.e., start radiation therapy, or perform the positioning process again. In addition to information representing the results of the alignment process, the medical image processing device 100 may also present information to the user by displaying, for example, CT images from the treatment planning stage and CT images from the treatment stage on the display device D. However, since CT images are three-dimensional images, they cannot be directly displayed on the display device D, which displays two-dimensional images. Therefore, the medical image processing device 100 generates one or more cross-sectional images corresponding to the CT images from the treatment planning stage and the CT images from the treatment stage, and displays them on the display device D. At this time, in order to make it easier for the user to visually compare the respective CT images, the medical image processing device 100 may display a difference image obtained by taking the difference between each cross-sectional image, or it may display a color map that is color-coded according to the magnitude of the difference value of each cross-sectional image.

[0024] The medical image processing apparatus 100 of the first embodiment will be described below. Figure 2 is a block diagram showing the schematic configuration of the medical image processing apparatus 100. The medical image processing apparatus 100 includes, for example, a first image acquisition unit 110, a second image acquisition unit 120, a treatment error acquisition unit 130, a difference calculation unit 140, and a difference statistics calculation unit 150.

[0025] 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 LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and 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 storage 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, or it may be stored in a removable storage medium (a non-transient storage 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 storage 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.

[0026] The first image acquisition unit 110 acquires a first fluoroscopic image of patient P before treatment, and parameters representing the position and posture at the time the first fluoroscopic image was taken. The first fluoroscopic image is a three-dimensional CT image representing the three-dimensional shape of the patient P's body, taken, for example, by a CT scanner 14 during the treatment planning stage when performing radiation therapy. The first fluoroscopic image is used to determine the direction (path including inclination and distance) and intensity of the treatment beam B to be irradiated onto patient P during radiation therapy. The determined direction (irradiation direction) and intensity of the treatment beam B are set in the first fluoroscopic image. The first fluoroscopic image is taken while maintaining a constant position and posture (hereinafter referred to as "body position") of patient P by fixing it to the bed 12. The parameters representing the patient P's position when the first fluoroscopic image was taken may be the position and orientation (shooting direction and magnification) of the CT scanner 14 when the first fluoroscopic image was taken, or, for example, the position and orientation of the bed 12 when the first fluoroscopic image was taken, that is, the setting values ​​set in the translational and rotational mechanisms provided on the bed 12 to maintain a constant position for the patient P. The first image acquisition unit 110 outputs the acquired first fluoroscopic image and parameters to the difference calculation unit 140. The first fluoroscopic image may be an image taken before radiation therapy is performed, for example, an image taken in the treatment room immediately before treatment is performed, or an image taken during a previous radiation therapy. The first image acquisition unit 110 may be equipped with an interface for connecting to the CT scanner 14 provided in the treatment device 10.

[0027] The second image acquisition unit 120 acquires a second fluoroscopic image of patient P immediately before the start of radiation therapy, and parameters representing the position and posture at the time the second fluoroscopic image was taken. The second fluoroscopic 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 14, in order to match the position of patient P when the treatment beam B is irradiated during radiation therapy. In other words, the second fluoroscopic image is an image taken by the CT scanner 14 when the treatment beam B is not being irradiated from the treatment beam irradiation gate 16. To put it another way, the second fluoroscopic image is a CT image taken at a different time than the first fluoroscopic image. In this case, although the first and second fluoroscopic images were taken at different times, the method of taking each image is the same. Therefore, the second fluoroscopic image is taken while the patient is in a position close to the position at which the first fluoroscopic image was taken. The parameters representing the patient P's position when the second fluoroscopic image is taken may be the position and orientation (shooting direction and magnification) of the CT scanner 14 when the second fluoroscopic image is taken, or, for example, the position and orientation of the bed 12 when the second fluoroscopic image is taken, that is, the settings set in the translational and rotational mechanisms provided on the bed 12 to bring the patient P's position closer to the position when the first fluoroscopic image was taken. The second image acquisition unit 120 outputs the acquired second fluoroscopic image and parameters to the difference calculation unit 140. The second image acquisition unit 120 may also have an interface for connecting to the CT scanner 14 provided in the treatment device 10. This interface may be the same as the interface provided in the first image acquisition unit 110.

[0028] The first and second fluoroscopic images are not limited to CT images taken by the CT scanner 14, but may be three-dimensional images taken by an imaging device different from the CT scanner 14, such as a CBCT scanner, MRI scanner, or ultrasound diagnostic device. For example, the first fluoroscopic image may be a CT image and the second fluoroscopic image may be a three-dimensional image taken by an MRI scanner. Conversely, the first fluoroscopic image may be a three-dimensional image taken by an MRI scanner and the second fluoroscopic image may be a CT image. The first and second fluoroscopic images are not limited to three-dimensional images, but may be four-dimensional images, such as CT images taken in motion. The first and second fluoroscopic images may be two-dimensional X-ray images taken from one or more directions.

[0029] As described above, both the first and second fluoroscopic images are three-dimensional CT images taken at different times. When taking the second fluoroscopic image, the patient P's position is brought as close as possible to the position when the first fluoroscopic image was taken. However, it is difficult to capture the second fluoroscopic image with the patient P in exactly the same position as when the first fluoroscopic image was taken. In other words, it is difficult to minimize changes in the internal state of the patient P or to fix them in the same position even with the use of restraints. Therefore, even if the patient P's position in the first fluoroscopic image and the patient P's position in the second fluoroscopic image are virtually placed identically in a predetermined three-dimensional space, there will be a slight discrepancy (for example, a few millimeters), and it is difficult to reproduce the patient P's position at the time the first fluoroscopic image was taken by taking only the second fluoroscopic image. The predetermined three-dimensional space refers to the space of the room coordinate system that is set in advance in the treatment room. Therefore, the medical image processing device 100 calculates an approximate image of the first fluoroscopic image through alignment processing, and further calculates the amount of positional and pose difference between the first fluoroscopic image and the second fluoroscopic image to determine the amount of movement of the bed 12 to match the position of patient P as captured in the first fluoroscopic image with the position of patient P as captured in the second fluoroscopic image. In other words, the medical image processing device 100 determines the amount of movement of the bed 12 to reproduce the position of patient P at the time the first fluoroscopic image was taken through alignment processing. At this time, the medical image processing device 100 may perform the alignment processing using either the first fluoroscopic image or the second fluoroscopic image, whichever has fewer pixels, as the reference. In this case, the time required for the alignment processing can be shortened.

[0030] Here, we will describe an example of alignment processing in the medical image processing device 100.

[0031] First, let's explain the treatment plan, which is performed before the alignment process in the medical image processing device 100. In the treatment plan, the energy of the treatment beam B (radiation) to be irradiated onto 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 stages are determined. 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 important organs in the surrounding area, for the first fluoroscopic image taken during the treatment planning stage (for example, a CT image taken by the CT scanner 14). Then, in the treatment plan, based on the information about the tumor specified by the person who plans the treatment (such as a doctor), the depth from the surface of patient P to the location of the tumor and the size of the tumor are determined, and the direction (path through which the treatment beam B passes) and intensity of the irradiation of the treatment beam B are determined.

[0032] Specifying the boundary between the tumor area and the area of ​​normal tissue is equivalent to specifying the location and volume of the tumor. This tumor volume is called the Gross Tumor Volume (GTV), Clinical Target Volume (CTV), Internal Target Volume (ITV), Planning Target Volume (PTV), etc. GTV is the volume of the tumor that can be seen with the naked eye from an image, and in radiotherapy, it is the volume to which a sufficient dose of treatment beam B must be irradiated. CTV is the volume that includes the GTV and the latent tumor to be treated. ITV is the volume obtained by adding a predetermined margin to the CTV, taking into account that the CTV will move due to predicted physiological patient P movements, etc. PTV is the volume obtained by adding a margin to the ITV, taking into account errors in the positioning of the patient P during treatment. The following relationship holds for these volumes.

[0033]

number

[0034] On the other hand, the volume of important organs located around tumors that are highly sensitive to radiation and are strongly affected by the radiation dose is called the Organ At Risk (OAR). The Planning Organ At Risk Volume (PRV) is specified as the OAR plus a predetermined margin. The PRV is specified by adding a margin to the volume (region) that should be irradiated while avoiding the OAR that should not be destroyed by radiation. The relationship between these volumes is given by equation (2) below.

[0035]

number

[0036] During the treatment planning stage, the direction (path) and intensity of the treatment beam B (radiation) to be irradiated onto patient P are determined based on a margin that takes into account the errors that may occur during the actual treatment.

[0037] Subsequently, during the radiation therapy treatment phase, when the medical image processing device 100 performs alignment processing, first, the first image acquisition unit 110 acquires a first fluoroscopic image and parameters representing the position and orientation of the first fluoroscopic image. The second image acquisition unit 120 acquires a second fluoroscopic image of patient P immediately before the start of treatment and parameters representing the position and orientation of the second fluoroscopic image. The medical image processing device 100 performs alignment processing using information regarding direction within the treatment room (hereinafter referred to as "direction information"). Direction information is information represented in a pre-set room coordinate system. Direction information includes, for example, information representing the irradiation direction of the treatment beam B and information representing the movement direction of the treatment table 12.

[0038] The information representing the irradiation direction of the treatment beam B represents the direction in which the treatment beam irradiation gate 16 irradiates the patient P with the treatment beam B within the treatment room. As shown in Figure 1, the treatment device 10 may have a fixed configuration in which the treatment beam irradiation gate 16 is fixed, but as mentioned above, it is also possible to have a configuration in which the treatment beam B can be irradiated from both vertical and horizontal directions, or a configuration in which the treatment beam irradiation gate 16 rotates simultaneously on the same axis of rotation as the imaging device, allowing the treatment beam B to be irradiated from various directions. Furthermore, the treatment beam B may be irradiated to the tumor area (range) within the patient P's body by scanning the beam of radiation (raster scan) or by irradiating within a predetermined planar area. In other words, there may be multiple paths through which the treatment beam B is actually irradiated to the tumor within the patient P's body. In these cases, the medical image processing device 100 acquires all irradiation directions (including multiple paths) in which the treatment beam B can be irradiated within the treatment room as information representing the irradiation direction of the treatment beam B.

[0039] The information representing the direction of movement of the bed 12 represents the direction in which the fixed patient P can be moved when the treatment beam B is irradiated by the bed 12 installed in the treatment room. The information representing the direction of movement of the bed 12 also includes information representing the angle in which the position of the patient P can be changed by the bed 12. For example, as described above, the bed 12 can move in position and orientation with six degrees of freedom by translation and rotation mechanisms. Therefore, the information representing the direction of movement of the bed 12 may also be information representing the directions of the six degrees of freedom of the bed 12. The information representing the direction of movement of the bed 12 may also be information representing the range of setting values ​​that can be set for the translation and rotation mechanisms. As mentioned above, when the bed 12 moves with fewer degrees of freedom than six (for example, four degrees of freedom), the medical image processing device 100 acquires information corresponding to the degrees of freedom in which the bed 12 moves. It is also possible that the movement of the bed 12 follows its own coordinate system, which is different from the room coordinate system that is set in advance in the treatment room. In this case, the medical image processing device 100 may acquire information about the direction of movement of the bed 12 in its own coordinate system as information representing the direction of movement of the bed 12.

[0040] The medical image processing device 100 performs alignment processing using information representing the irradiation direction of the acquired treatment beam B and information representing the movement direction of the treatment table 12. The medical image processing device 100 outputs a movement control signal to the treatment device 10 according to the result of the alignment processing. As a result, the treatment device 10 moves the treatment table 12 in accordance with the movement control signal output by the medical image processing device 100 so that the current position of patient P is close to the position of patient P at the treatment planning stage.

[0041] The treatment error acquisition unit 130 acquires errors in radiation therapy that did not appear during the treatment planning stage (hereinafter referred to as "treatment errors"). The treatment error acquisition unit 130 outputs the acquired treatment errors to the difference calculation unit 140. Treatment errors are errors that may occur when performing radiation therapy.

[0042] Treatment errors are, for example, movement errors of the treatment bed 12 that are expected (estimated) to occur when the position and orientation of the treatment bed 12 are moved in accordance with the movement control signal. Movement errors are, for example, minute mechanical control errors that may occur when the translational and rotational mechanisms provided on the treatment bed 12 move the treatment bed 12. For example, if the treatment bed 12 is a robotic arm type treatment bed device attached to the end of an arm, the treatment bed 12 can be moved to any coordinate position in the room coordinate system within the treatment room by moving the angle of the joints and the position of the base of the robotic arm according to the movement control signal. However, even in this case, since the control of the robotic arm is mechanical control, there is a possibility that minute mechanical control errors may occur. Such movement errors of the treatment bed 12 can be measured, for example, by measuring the coordinates of the treatment bed 12 using a high-precision distance sensor fixed in the treatment room, finding the difference between the coordinates and the coordinates indicated by the movement control signal, and measuring this difference as the movement error of the treatment bed 12. However, if it is difficult to perform high-precision measurements using distance sensors each time radiation therapy is performed due to time constraints, the movement error for the current radiation therapy may be determined based on the distribution of movement errors measured, for example, when performing periodic inspections of the treatment system 1. This distribution of movement errors may be prepared separately for each of the three translational axes and three rotational axes of the treatment table 12, i.e., for all six axes.

[0043] Treatment error is, for example, the expected (estimated) discrepancy between the irradiation of treatment beam B planned during the treatment planning stage and the irradiation of treatment beam B during the treatment stage. The discrepancy that occurs when irradiating with treatment beam B includes, for example, the irradiation position including the direction of treatment beam B irradiated onto patient P (i.e., the path including the inclination and distance of the irradiated treatment beam B) and the intensity discrepancy (error). Factors that can cause such discrepancies when irradiating with treatment beam B include various factors that affect the irradiation system of treatment beam B, such as weather conditions such as temperature, atmospheric pressure, and season, and temporal fluctuations such as time of day. If it is difficult to measure this discrepancy (error) in the irradiation position of treatment beam B each time radiation therapy is performed, the magnitude of the error may be determined based on the experience of the user of treatment system 1 (such as a doctor).

[0044] Treatment error refers to, for example, the installation error of the fixation device used to secure patient P to the bed 12, which is expected (estimated) to differ between the treatment planning stage and the treatment stage. Installation error is an error that may occur when the gap between patient P and the fixation device differs between the treatment planning stage and the treatment stage due to factors such as changes in body shape in response to increases or decreases in patient P's weight. The magnitude of the installation error may be predetermined according to, for example, the patient P's weight, chest circumference, waist circumference, and other body surface values ​​of patient P.

[0045] Treatment errors are errors related to the internal state of patient P, which are expected (estimated) to occur due to changes in the patient's body over time. Factors contributing to errors related to the internal state of patient P may include physiological activities such as the location of intestinal gas, pulsation, respiration, edema, and blood flow. The magnitude of these errors related to the internal state of patient P may be determined based on these values ​​measured for patient P during radiation therapy, for example.

[0046] Such treatment errors may be assumed (estimated) by the user (such as a doctor) and input by operating an input device such as a user interface unit (not shown) provided by the medical image processing device 100. The user interface unit (input device) may be, for example, an input device such as a keyboard, a pointing device such as a mouse or pen-type stylus, or an operating device such as buttons or switches. The user interface unit may be equipped with a pressure sensor as an input device and configured as a touch panel combined with the display device D. In this case, the user inputs the treatment error by performing various touch operations (such as tapping or flicking) on ​​the image displayed on the display device D. The user inputs information on the acceptable range of treatment errors after considering various conditions, such as the area of ​​the patient P receiving radiation therapy, whether there are areas near the area to which the treatment beam B should not be irradiated, and the depth to which the treatment beam B is irradiated. The treatment error acquisition unit 130 acquires the treatment error input by the user and outputs the acquired treatment error to the difference calculation unit 140.

[0047] The difference calculation unit 140 calculates (generates) a difference image between the first fluoroscopic image and the second fluoroscopic image, based on the first fluoroscopic image and parameters output by the first image acquisition unit 110, the second fluoroscopic image and parameters output by the second image acquisition unit 120, and the treatment error output by the treatment error acquisition unit 130, while virtually changing the parameters of the second fluoroscopic image (position and posture when the second fluoroscopic image was taken) according to the treatment error in radiotherapy. In other words, the difference calculation unit 140 calculates a difference image with a virtually shifted patient P position, taking into account the treatment error in radiotherapy that did not appear in the treatment planning stage. More specifically, the difference calculation unit 140 calculates a difference image by taking the difference between the first fluoroscopic image and the second fluoroscopic image with the virtual perturbation applied to the patient P's position as seen in the second fluoroscopic image after the alignment process, that is, by virtually shifting the patient P's position, based on the treatment error. The difference is then taken between the first fluoroscopic image and the second fluoroscopic image with the virtual perturbation applied to the patient P's position (hereinafter, to distinguish it from the second fluoroscopic image before the perturbation, the perturbed second fluoroscopic image will be referred to as the "second P fluoroscopic image"). The size (number of pixels) of the difference image calculated by the difference calculation unit 140 may be the same as or different from the size (number of pixels) of the first fluoroscopic image and the second fluoroscopic image after the alignment process. For example, the difference calculation unit 140 may calculate a difference image with a size (number of pixels) corresponding to the range for which the difference statistics calculation unit 150, described later, calculates the difference statistics.

[0048] The difference calculation unit 140 may, based on the treatment error, sequentially change the virtual perturbation applied to the position of patient P as seen in the second fluoroscopic image after the alignment process to a different perturbation, that is, sequentially shift the position of patient P by a different amount of displacement, and each time calculate a difference image by taking the difference with the first fluoroscopic image. In other words, the difference calculation unit 140 may apply multiple perturbations to the position of patient P as seen in the second fluoroscopic image after the alignment process, and calculate the same number of difference images as the number of times perturbations are applied. The number of times the difference calculation unit 140 calculates difference images, that is, the number of times virtual perturbations are applied to the position of patient P, may be a predetermined number depending on the processing capacity of the difference calculation unit 140 or the medical image processing device 100, or it may be a number specified by the user (for example, specified by the user by operating the user interface unit (not shown)).

[0049] The difference calculation unit 140 calculates the difference image by, for example, finding the difference in pixel values ​​(CT values) between pixels (voxels) at the same position in the first fluoroscopic image and the second P fluoroscopic image after alignment processing and the application of a virtual perturbation. However, it is also possible that the two fluoroscopic images used to calculate the difference image have different dimensions, for example, when the first fluoroscopic image is a three-dimensional CT image and the second fluoroscopic image is a two-dimensional X-ray image. In this case, the difference calculation unit 140 converts the three-dimensional CT image into a DRR image to match the dimensions of the first fluoroscopic image and the second fluoroscopic image after alignment processing, then applies a virtual perturbation and calculates the difference image. In this case, the difference calculation unit 140 calculates the difference image by, for example, finding the difference in pixel values ​​between pixels at the same position in the first fluoroscopic image and the second P fluoroscopic image. The difference calculation unit 140 may calculate the difference image by applying various image processing to each of the perspective images, such as smoothing to suppress noise, edge enhancement, and transformation to convert the pixel values ​​to the direction of the gradient, and then applying a virtual perturbation to find the difference in the pixel values ​​of each perspective image.

[0050] The difference image is an image calculated (generated) by focusing on irradiating tumors and tissues present in the patient P's body with the dose of treatment beam B determined in the treatment planning stage. For example, if the second fluoroscopic image is a CT image, the difference calculation unit 140 calculates the dose of treatment beam B to be irradiated in the same way as in the treatment planning stage, and generates the difference image by calculating the difference in dose between the second P fluoroscopic image and the first fluoroscopic image for each pixel. The difference calculation unit 140 may also generate the difference image by converting the first fluoroscopic image and the second P fluoroscopic image, respectively, into the energy attenuation of treatment beam B in the tumor, and calculating the difference. The energy attenuation of treatment beam B can be obtained, for example, by integrating the pixel values ​​(CT values) of pixels (voxels) located on the path through which the irradiated treatment beam B passes. The energy attenuation of treatment beam B may also be converted into, for example, water equivalent thickness. Water equivalent thickness is a value that expresses the energy attenuation of the treatment beam B, which differs for each tissue (substance), as the thickness of water, which is the same substance, and can be converted based on the CT value. For example, if the CT value represents bone, the energy attenuation when the treatment beam B passes through bone is large, so the water equivalent thickness will be a large value. For example, if the CT value represents fat, the energy attenuation when the treatment beam B passes through fat is small, so the water equivalent thickness will be a small value. For example, if the CT value represents air, there is no energy attenuation when the treatment beam B passes through air, so the water equivalent thickness will be "0". By converting each CT value contained in the CT image into water equivalent thickness, the energy attenuation by each pixel located in the path of the treatment beam B can be expressed on the same standard. As a conversion formula for converting CT values ​​to water equivalent thickness, for example, a regression formula based on experimentally obtained nonlinear conversion data may be used. Various literatures have been published regarding experimentally obtained nonlinear conversion data.

[0051] The difference calculation unit 140 outputs the calculated difference image, or information representing the difference (amount of displacement) between the first perspective image and the second P perspective image represented by the difference image (hereinafter, these together are referred to as the "difference image"), to the difference statistics calculation unit 150.

[0052] The difference statistics calculation unit 150 calculates the difference (amount of shift) between the first perspective image and the second P perspective image represented by the difference image output by the difference calculation unit 140 (hereinafter referred to as "difference statistics"). Difference statistics are numerical values ​​(data) such as the mean of the absolute values ​​of the pixel values ​​of the difference image, the standard deviation, the median, and the maximum value. Difference statistics are also values ​​(data) used to generate graphs such as the distribution of pixel values ​​of the difference image or a histogram. Difference statistics may also be values ​​(data) used to generate graphs such as the cumulative distribution of errors or a cumulative histogram. Difference statistics are an example of "statistics".

[0053] The range over which the differential statistics calculation unit 150 calculates differential statistics is, for example, the entire area of ​​the differential image. The range over which the differential statistics calculation unit 150 calculates differential statistics may be narrowed down to, for example, a specific area such as the tumor or other organs of patient P included in the differential image, or a designated area such as the PTV determined at the treatment planning stage. The range over which the differential statistics calculation unit 150 calculates differential statistics may also be narrowed down to, for example, only the boundary portion within the PTV. If the range over which the differential statistics calculation unit 150 calculates differential statistics is narrowed, the differential calculation unit 140 may also set the range over which it calculates differential images to correspond to the range over which the differential statistics calculation unit 150 calculates differential statistics. In this case, the amount of computation required for the differential calculation unit 140 to calculate the differential image can be reduced. The range over which the differential statistics calculation unit 150 calculates differential statistics may be changed, for example, according to the irradiation direction and irradiation range of the treatment beam B. For example, the differential statistics calculation unit 150 may calculate the differential statistics by focusing on the area in front of the tumor (closer to the treatment beam irradiation gate 16) and the area behind the tumor (farther from the treatment beam irradiation gate 16), depending on the distance from the treatment beam irradiation gate 16 to the tumor inside the patient P's body. In other words, the differential statistics calculation unit 150 may calculate the differential statistics based on the irradiation direction of the treatment beam B and the spatial positional relationship between the treatment beam irradiation gate 16 that irradiates the treatment beam B and the tumor. This allows the differential statistics calculation unit 150 to calculate differential statistics that reflect the error conditions for the dose of treatment beam B, which are set loosely in front of the tumor and strictly in behind the tumor, so that the area behind the tumor is not irradiated with treatment beam B and remains as is, or that the area of ​​normal tissue behind the tumor is irradiated with treatment beam B. The range over which the differential statistics calculation unit 150 calculates the differential statistics may, for example, be each region divided by segmentation performed by image processing during radiotherapy in the treatment system 1. For example, the differential statistics calculation unit 150 may divide the area into regions segmented according to anatomical tissue and calculate the differential statistics. The differential statistics calculated by the differential statistics calculation unit 150 may be a vector value combining the above.

[0054] The differential statistics calculation unit 150 outputs data representing the calculated differential statistics (hereinafter simply referred to as "differential statistics"). The differential statistics output by the differential statistics calculation unit 150 are presented to the user by the medical image processing device 100, for example, and are referenced when determining whether the alignment process performed by the medical image processing device 100 is being carried out correctly. The method by which the medical image processing device 100 presents the differential statistics to the user at this time may be to display an image and / or numerical value representing the differential statistics on a display device D, for example, or to display it on a liquid crystal display (not shown) provided by the medical image processing device 100.

[0055] The following describes the process for outputting differential statistics in the medical image processing device 100 (hereinafter referred to as "differential statistics calculation process"). Figure 3 is a flowchart showing the process for outputting differential statistics in the medical image processing device 100. Before the medical image processing device 100 performs the differential statistics calculation process, that is, before radiation therapy is performed (for example, about a week before), a treatment plan is created based on the first fluoroscopic image that has been taken. Furthermore, immediately before the medical image processing device 100 performs the differential statistics calculation process, that is, immediately before starting radiation therapy, a second fluoroscopic image is taken. In radiation therapy, the treatment beam B may be irradiated multiple times (including on different days) to treat the same patient P. Therefore, if it is the second or subsequent radiation therapy for the same patient P, the second fluoroscopic image, in which the position of patient P was aligned during the previous treatment, may be used as the first fluoroscopic image, and yet another treatment plan may be created. Then, when the medical image processing device 100 performs the differential statistics calculation process, an alignment process is performed.

[0056] The medical image processing device 100 primarily focuses on calculating differential statistics that are referenced by the user when determining whether the alignment process for positioning patient P during radiation therapy in the treatment system 1 is being performed correctly. Therefore, further detailed explanations regarding the processing when acquiring the first fluoroscopic image and the second fluoroscopic image (in this case, CT images), as well as the alignment process, will be omitted. In the following explanation, it will be assumed that the treatment plan based on the first fluoroscopic image has been completed, the second fluoroscopic image has been acquired in the treatment system 1, and the alignment process has already been completed at least once. Accordingly, in the following explanation, the second fluoroscopic image will be assumed to be the second fluoroscopic image after the alignment process.

[0057] First, when the medical image processing device 100 starts the differential statistics calculation process, the first image acquisition unit 110 acquires a first fluoroscopic image and parameters representing the position and orientation of the first fluoroscopic image, the second image acquisition unit 120 acquires a second fluoroscopic image and parameters representing the position and orientation of the second fluoroscopic image, and the treatment error acquisition unit 130 acquires the treatment error (step S100). The first image acquisition unit 110 outputs the acquired first fluoroscopic image and its parameters to the differential calculation unit 140. The second image acquisition unit 120 outputs the acquired second fluoroscopic image and its parameters to the differential calculation unit 140. The treatment error acquisition unit 130 outputs the acquired treatment error to the differential calculation unit 140.

[0058] Next, the difference calculation unit 140 modifies the parameters representing the position and orientation of the second fluoroscopic image after the alignment process based on the treatment error obtained by the treatment error acquisition unit 130 (step S101). In other words, the difference calculation unit 140 applies a virtual perturbation to the body position of patient P as captured in the second fluoroscopic image after the alignment process.

[0059] Next, the difference calculation unit 140 calculates a difference image by taking the difference between the first fluoroscopic image and the second fluoroscopic image (second P fluoroscopic image) in which a virtual perturbation has been applied to the patient P's body position (step S102). The difference calculation unit 140 outputs the calculated difference image to the difference statistics calculation unit 150.

[0060] Next, the difference statistics calculation unit 150 calculates the difference statistics obtained from the difference image output by the difference calculation unit 140 (step S103). The difference statistics calculation unit 150 outputs the calculated difference statistics. Then, the medical image processing device 100 presents the difference statistics output by the difference statistics calculation unit 150 to the user.

[0061] Through this process, the differential statistics calculation process of the medical image processing device 100 involves the difference calculation unit 140 calculating a difference image by changing the parameters representing the position and orientation of the second fluoroscopic image after the alignment process based on the treatment error (by applying a virtual perturbation), and the difference statistics calculation unit 150 calculating the difference statistics based on the difference image. The medical image processing device 100 repeats the above-described differential statistics calculation process (for the same number of times as the number of times a virtual perturbation was applied) to calculate multiple difference images and calculates the difference statistics based on each difference image. The medical image processing device 100 then presents each calculated difference statistic to the user. This allows the user to refer to the presented difference statistics and determine whether the alignment process performed by the medical image processing device 100 was performed correctly. If the user determines that the alignment process performed by the medical image processing device 100 was not performed correctly, the user can instruct the medical image processing device 100 to perform the alignment process again.

[0062] Here, the difference statistics presented by the medical image processing device 100 are presented in addition to, or as a substitute for, images used in conventional treatment systems to visually confirm whether the target area for radiation therapy matches the position in the treatment plan. These images are superimposed by making the first fluoroscopic image and the second fluoroscopic image after alignment processing semi-transparent. Moreover, the difference statistics presented by the medical image processing device 100 are quantitative data representing the discrepancy (error) between the first fluoroscopic image and the second fluoroscopic image after alignment processing, in other words, the degree of agreement of the patient P's position. Therefore, ideally, even in conventional treatment systems, the patient P's position after alignment processing matches, but for the user, it is difficult to judge from the degree of overlap between the two fluoroscopic images (the first fluoroscopic image and the second fluoroscopic image after alignment processing). This makes it easier and more accurate to determine whether the alignment processing by the medical image processing device 100 has been performed correctly. As a result, in the treatment system 1 equipped with the medical image processing device 100, it is possible to perform radiation therapy that does not differ in effectiveness due to factors such as the skill of the user performing the check, unlike in conventional treatment systems where the user visually checks whether the alignment process by the medical image processing device 100 is being performed correctly.

[0063] Furthermore, the differential statistics presented by the medical image processing device 100 take into account treatment errors in radiation therapy that did not appear during the treatment planning stage, and allow for the determination of whether or not the radiation therapy can be continued even if the patient P's position shifts during the radiation therapy. Therefore, the user can also determine whether the results of the alignment processing by the medical image processing device 100 can accommodate changes in the patient's condition (such as changes in posture) that are expected (estimated) to change over time as the radiation therapy progresses, or errors in the movement of the treatment table 12.

[0064] As described above, in the medical image processing device 100, the first image acquisition unit 110 acquires a first fluoroscopic image of patient P taken before treatment, and parameters representing the position and posture at the time the first fluoroscopic image was taken. The second image acquisition unit 120 acquires a second fluoroscopic image of patient P taken immediately before the start of treatment, and parameters representing the position and posture at the time the second fluoroscopic image was taken. Furthermore, the medical image processing device 100's treatment error acquisition unit 130 acquires treatment errors in radiotherapy that did not appear during the treatment planning stage. Then, the medical image processing device 100's difference calculation unit 140 modifies (hypothesizes) the parameters representing the position and posture of the second fluoroscopic image after alignment processing based on the treatment errors, and calculates a difference image. Subsequently, the medical image processing device 100's difference statistics calculation unit 150 calculates difference statistics based on the difference image. Finally, the medical image processing device 100 presents the calculated difference statistics to the user. As a result, in the treatment system 1 equipped with the medical image processing device 100, the user can refer to the presented difference statistics to determine whether the current alignment process by the medical image processing device 100 is being performed correctly.

[0065] As described above, the medical image processing device 100 includes a first image acquisition unit 110 that acquires a first fluoroscopic image taken inside the body of patient P, a second image acquisition unit 120 that acquires a second fluoroscopic image taken inside the body of patient P at a different time than the first fluoroscopic image, a treatment error acquisition unit 130 that acquires treatment errors that occur when performing alignment processing to match the position of patient P in the second fluoroscopic image to the position of patient P in the first fluoroscopic image based on the first and second fluoroscopic images, or treatment errors that occur in radiotherapy, a difference calculation unit 140 that applies a virtual perturbation to the position of patient P in the second fluoroscopic image based on the treatment error and calculates a difference image between the perturbed second fluoroscopic image and the first fluoroscopic image, and a difference statistics calculation unit 150 that calculates difference statistics of the difference between the first fluoroscopic image and the perturbed second fluoroscopic image based on the difference image. As a result, the medical image processing device 100 can present the difference statistics calculated by the difference statistics calculation unit 150 to the user.

[0066] As described above, the difference calculation unit 140 may apply multiple perturbations to the position of patient P in the second fluoroscopic image, calculate a difference image for each applied perturbation, and the difference statistics calculation unit 150 may calculate a difference statistic corresponding to each perturbation based on each difference image. In this way, the medical image processing device 100 can present to the user each difference statistic calculated by applying multiple virtual perturbations.

[0067] As described above, the treatment system 1 comprises a medical image processing device 100, a treatment beam irradiation gate 16 for irradiating the patient P with a treatment beam B, a CT scanning device 14 for capturing a first fluoroscopic image and a second fluoroscopic image, and a treatment table 12 for supporting and fixing the patient P. With this, the treatment system 1 allows the user to perform radiation therapy at the position of the patient P determined by the user by referring to the difference statistics presented by the medical image processing device 100.

[0068] (Second embodiment) The second embodiment will now be described. In the first embodiment, a configuration was described in which the differential statistics calculation unit 150 calculates and presents the differential statistics to the user. In other words, a configuration was described in which the user makes a judgment as to whether or not the alignment process by the medical image processing device 100 has been performed correctly. In the second embodiment, a configuration and method will be described that can automatically determine whether or not it is necessary to adjust the position of patient P after the alignment process, as support for the user's judgment.

[0069] 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 200 of the second embodiment. In the following description, the treatment system equipped with the medical image processing device 200 will be referred to as "treatment system 2".

[0070] In the following description, components of the treatment system 2 equipped with the medical image processing device 200 are assigned the same reference numerals as components of the treatment system 1 equipped with the medical image processing device 100, and further detailed explanations are omitted.

[0071] The medical image processing device 200, like the medical image processing device 100, calculates differential statistics through differential statistics calculation processing and presents the differential statistics to the user. Furthermore, based on the calculated differential statistics, the medical image processing device 200 determines whether or not it is necessary to adjust the position of patient P and presents the determination result to the user.

[0072] The configuration of the medical image processing device 200 that constitutes the treatment system 2 will be described below. Figure 4 is a block diagram showing the schematic configuration of the medical image processing device 200 of the second embodiment. The medical image processing device 200 includes, for example, a first image acquisition unit 110, a second image acquisition unit 120, a treatment error acquisition unit 130, a difference calculation unit 140, a difference statistics calculation unit 150, and a determination unit 260. The medical image processing device 200 is configured by adding the determination unit 260 to the medical image processing device 100.

[0073] The determination unit 260 determines whether or not it is necessary to adjust the position of patient P in the alignment process of the medical image processing device 200, based on the difference statistics output by the difference statistics calculation unit 150. The determination of whether or not the position of patient P needs to be adjusted in the determination unit 260 is performed, for example, by comparing the magnitude relationship between the difference statistics and a predetermined threshold. The determination of whether or not the position of patient P needs to be adjusted in the determination unit 260 may also be performed, for example, by comparing the magnitude relationship between the output value of a model equation such as a weighted sum of multiple difference statistics and a predetermined threshold. The determination of whether or not the position of patient P needs to be adjusted in the determination unit 260 may also be performed, for example, by calculating the proportion of pixel values ​​greater than or equal to a predetermined difference value in the distribution of pixel values ​​of the difference image, and comparing the magnitude relationship between this calculated value and a predetermined threshold. The predetermined threshold is input to the medical image processing device 200 or the determination unit 260 by the user operating the user interface unit (not shown).

[0074] The determination unit 260 outputs a result (determination result) indicating whether or not patient P's position adjustment is necessary. The determination result output by the determination unit 260 is, for example, presented to the user by the medical image processing device 200 and referred to by the user when deciding whether to perform the position adjustment process again. The method by which the medical image processing device 200 presents the determination result to the user at this time may be, for example, by displaying an image representing the determination result on the display device D, or by displaying it on a liquid crystal display (not shown) provided by the medical image processing device 200, or by indicating the determination result by turning on / off or changing the color of LEDs or lamps provided by the medical image processing device 200.

[0075] The following describes the process for determining whether or not to adjust the position of patient P in the medical image processing device 200 (hereinafter referred to as the "adjustment determination process"). Figure 5 is a flowchart showing the process for determining whether or not to adjust the position of patient P in the medical image processing device 200. In the adjustment determination process in the medical image processing device 200, the process up to the calculation of the difference statistics by the difference statistics calculation unit 150 is the same as the difference statistics calculation process in the medical image processing device 100, so a detailed explanation will be omitted again.

[0076] In step S103, the differential statistics calculation unit 150 calculates the differential statistics and outputs the calculated differential statistics to the determination unit 260. Based on the differential statistics output by the differential statistics calculation unit 150, the determination unit 260 determines whether or not patient P's position adjustment is necessary (step S204). The impact determination unit 206 outputs the determination result. The medical image processing device 200 then presents the determination result output by the determination unit 260 to the user.

[0077] With this configuration, operation, and processing, the medical image processing device 200, in the adjustment judgment process, determines whether or not it is necessary to adjust the position of patient P based on the difference statistics calculated by the difference statistics calculation unit 150, similar to the medical image processing device 100. The medical image processing device 200 then presents the calculated difference statistics and the judgment result determining whether or not it is necessary to adjust the position of patient P to the user. This allows the user to quantitatively judge the degree of agreement of the position of patient P, etc., with the medical image processing device 200, similar to the medical image processing device 100, and to receive support in determining whether or not it is necessary to adjust the position of patient P after the alignment process. If the medical image processing device 200 determines that the current alignment process has not been performed correctly, or that it is necessary to adjust the position of patient P, the user can instruct the medical image processing device 200 to perform the alignment process again or to adjust the position of patient P. As a result, the treatment system 2 equipped with the medical image processing device 200 can perform more effective radiotherapy, similar to the treatment system 1 equipped with the medical image processing device 100.

[0078] As described above, in the medical image processing device 200, similar to the medical image processing device 100, the first image acquisition unit 110 acquires a first fluoroscopic image of patient P taken before treatment, and parameters representing the position and posture at the time the first fluoroscopic image was taken. The second image acquisition unit 120 acquires a second fluoroscopic image of patient P taken immediately before the start of treatment, and parameters representing the position and posture at the time the second fluoroscopic image was taken. Furthermore, in the medical image processing device 200, similar to the medical image processing device 100, the treatment error acquisition unit 130 acquires treatment errors in radiotherapy that did not appear in the treatment planning stage. Then, in the medical image processing device 200, similar to the medical image processing device 100, the difference calculation unit 140 calculates a difference image by changing the parameters representing the position and posture of the second fluoroscopic image after alignment processing based on the treatment error (by applying a virtual perturbation). Subsequently, in the medical image processing device 200, similar to the medical image processing device 100, the difference statistics calculation unit 150 calculates difference statistics based on the difference image. Furthermore, the medical image processing device 200, like the medical image processing device 100, presents the calculated difference statistics to the user. In addition, the medical image processing device 200's determination unit 260 determines whether or not it is necessary to adjust the position of patient P based on the difference statistics calculated by the difference statistics calculation unit 150. As a result, in the treatment system 2 equipped with the medical image processing device 200, just like in the treatment system 1 equipped with the medical image processing device 100, the user can refer to the presented difference statistics to determine whether or not the position adjustment process performed by the medical image processing device 200 is being carried out correctly. Furthermore, in the treatment system 2 equipped with the medical image processing device 200, the user can refer to the determination result by the determination unit 260 to decide whether or not to adjust the position of patient P.

[0079] Furthermore, the medical image processing device 200 allows the determination unit 260 to quantitatively and automatically determine whether or not it is necessary to adjust the position of patient P. This enables the realization of a treatment system that automatically starts adjusting the position of patient P faster than the user can decide and give instructions. In other words, it becomes possible to realize a treatment system that automatically performs positioning processing to position patient P in a position suitable for radiation therapy.

[0080] As described above, the medical image processing device 200 further includes a determination unit 260 that determines the result of the alignment process based on differential statistics, compared to the medical image processing device 100 of the first embodiment. This allows the medical image processing device 200 to present to the user the determination result of whether or not the determination unit 260 has determined that the position of patient P needs to be adjusted.

[0081] (Third embodiment) The third embodiment will now be described. In the first and second embodiments, the configuration, operation, and processing of the medical image processing device 100 or medical image processing device 200 were described assuming that the alignment process had already been completed at least once. In the third embodiment, a medical image processing device including a configuration for performing the alignment process will be described.

[0082] The configuration of the treatment system equipped with the medical image processing device of the third 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 300 of the third embodiment. In the following description, the treatment system equipped with the medical image processing device 300 will be referred to as "treatment system 3".

[0083] In the following description, in the components of the treatment system 3 equipped with the medical image processing device 300, the same reference numerals are used for components that are the same as those in the treatment system 1 equipped with the medical image processing device 100, or the treatment system 2 equipped with the medical image processing device 200 of the second embodiment, and further detailed explanations are omitted.

[0084] Similar to the medical image processing devices 100 and 200, the medical image processing device 300 performs positioning processing to align the patient P's position during radiation therapy based on the CT image output by the CT scanner 14, and outputs a movement control signal to move the patient bed 12 to align the irradiation direction of the treatment beam B emitted from the treatment beam irradiation gate 16 with the direction set in the treatment planning stage. Furthermore, similar to the medical image processing devices 100 and 200, the medical image processing device 300 calculates differential statistics through differential statistics calculation processing and presents the differential statistics to the user. In addition, similar to the medical image processing device 200, the medical image processing device 300 determines whether or not it is necessary to adjust the patient P's position based on the calculated differential statistics and presents the determination result to the user.

[0085] The configuration of the medical image processing device 300, which constitutes the treatment system 3, will be described below. Figure 6 is a block diagram showing the schematic configuration of the medical image processing device 300 of the third embodiment. The medical image processing device 300 includes a first image acquisition unit 110, a second image acquisition unit 120, a treatment error acquisition unit 130, a difference calculation unit 140, a difference statistics calculation unit 150, a determination unit 260, a position error calculation unit 370, a treatment table control unit 380, and a presentation data processing unit 390. The medical image processing device 300 is configured by adding the position error calculation unit 370, the treatment table control unit 380, and the presentation data processing unit 390 to the medical image processing device 200. Accordingly, the difference calculation unit 140 in the medical image processing device 200 has been replaced by the difference calculation unit 140a.

[0086] The position error calculation unit 370 performs alignment processing based on the first fluoroscopic image and parameters output by the first image acquisition unit 110 and the second fluoroscopic image and parameters output by the second image acquisition unit 120. More specifically, the position error calculation unit 370 acquires the first fluoroscopic image and parameters representing the position and orientation of the first fluoroscopic image, and acquires the second fluoroscopic image and parameters representing the position and orientation of the second fluoroscopic image. Then, the position error calculation unit 370 calculates the amount of movement of the position and orientation of the second fluoroscopic image so that the patient's position when the second fluoroscopic image was taken matches the patient's position when the first fluoroscopic image was taken.

[0087] Here, matching the patient's position when the second fluoroscopic image was taken with the patient's position when the first fluoroscopic image was taken means solving the problem of calculating the similarity between the first and second fluoroscopic images while varying the parameters representing the position and orientation of the second fluoroscopic image, and finding the parameters that maximize the similarity. Therefore, in the alignment process of the position error calculation unit 370, the efficiency of selecting the similarity and searching for parameters greatly affects the accuracy of patient P alignment and the calculation time (processing time). Similarity is a scalar value obtained by calculating a difference image while changing the parameters of the second fluoroscopic image, similar to the difference calculation unit 140, and finding the difference (amount of shift) between the first fluoroscopic image and the second fluoroscopic image with the changed parameters represented by the calculated difference image. As for the parameter search method, optimization methods such as the gradient method, Newton's method, and the Lucas-Kanade method (LK method) are used.

[0088] The position error calculation unit 370 outputs the calculated position and orientation displacement amounts of the second perspective image to the difference calculation unit 140a and the bed control unit 380 as the result of the alignment process.

[0089] As a result, the difference calculation unit 140a moves the parameters of the second perspective image based on the amount of movement represented by the processing result output by the position error calculation unit 370, applies a virtual perturbation to this second perspective image as the second perspective image after alignment processing, and calculates the difference image in the same way as the difference calculation unit 140.

[0090] The bed control unit 380 generates a movement control signal to control the translation and rotation mechanisms provided on the bed 12, based on the amount of movement represented by the processing result output by the position error calculation unit 370 and the determination result of whether or not patient P's position adjustment is necessary, output by the determination unit 260. The bed control unit 380 outputs the generated movement control signal to the treatment device 10. As a result, the treatment device 10 controls the translation and rotation mechanisms in accordance with the movement control signal output by the bed control unit 380, moving the bed 12 so that the current position of patient P, which is fixed to the bed 12, approaches the position of patient P at the treatment planning stage. As a result, in the treatment system 3 equipped with the medical image processing device 300, the irradiation direction of the treatment beam B irradiated onto patient P from the treatment beam irradiation gate 16 is aligned with the direction set at the treatment planning stage, and radiation therapy can be performed.

[0091] The presentation data processing unit 390 generates presentation data for presenting results and information calculated by the medical image processing device 300 to the user. The presentation data includes, for example, the first fluoroscopic image and parameters output by the first image acquisition unit 110, the second fluoroscopic image and parameters output by the second image acquisition unit 120, the treatment error output by the treatment error acquisition unit 130, the difference image output by the difference calculation unit 140 (including information representing the difference (amount of displacement) between the first fluoroscopic image and the second P fluoroscopic image represented by the difference image), the difference statistics output by the difference statistics calculation unit 150, and the judgment result output by the judgment unit 260. The presentation data processing unit 390 generates an image representing this information as presentation data and presents the information to the user by displaying this presentation data on the display device D.

[0092] Here, we will describe an example of the presentation data that the presentation data processing unit 390 generates and displays on the display device D. As described above, the presentation data processing unit 390 displays information such as the first fluoroscopic image, the second fluoroscopic image, treatment error, difference image, difference statistics, and judgment result on the display device D. Below, we will describe an example in which the presentation data processing unit 390 presents difference statistics to the user as a representative example of this information.

[0093] Figure 7 shows an example of presentation data generated by the presentation data processing unit 390 of the medical image processing device 300. Figure 7 shows an example of presentation data in which the difference statistics calculated by the difference statistics calculation unit 150 are represented graphically. In Figure 7, for illustrative purposes, an example is shown in which the movement error (treatment error) of the treatment table 12 is exaggerated. More specifically, Figures 7(a) to (c) show an example in which the difference calculation unit 140a calculates a difference image by applying treatment errors (movement errors of the treatment table 12) of ±0.5 mm and ±1.0 mm as virtual perturbations for each of the three axes of the translation mechanism, and the difference statistics calculation unit 150 calculates the error of the water equivalent path length (WEL) at each pixel of the difference image, and the difference statistics are used as a histogram representing the distribution of errors. Figures 7(d) to (f) show an example in which the same difference statistics as in Figures 7(a) to (c) are used as a cumulative histogram representing the cumulative distribution of errors. Figures 7(a) and (d) show examples where a virtual perturbation is applied in the X-axis direction (see Figure 1), Figures 7(b) and (e) show examples where a virtual perturbation is applied in the Y-axis direction (see Figure 1), and Figures 7(c) and (f) show examples where a virtual perturbation is applied in the Z-axis direction (see Figure 1). In Figures 7(a) to (c), the horizontal axis represents the difference value (absolute value) of the equivalent water thickness, and the vertical axis represents the number of pixels with the same difference value. In Figures 7(d) to (f), the horizontal axis represents the difference value (absolute value) of the equivalent water thickness, and the vertical axis represents the proportion of pixels with the same difference value. Figures 7(a) to (f) also show the difference statistics when the alignment process is complete, i.e., when the perturbation is 0.0 mm.

[0094] For example, from the cumulative histograms shown in Figures 7(d) to (f), it can be seen that when the alignment process is complete, the difference in water equivalent thickness is within approximately 1.0 mm in all three axial directions of the translation mechanism, and approximately 90% of these differences are within approximately 0.5 mm. Furthermore, from the histograms shown in Figures 7(a) to (c) and the cumulative histograms shown in Figures 7(d) to (f), it can be seen whether the difference in water equivalent thickness increases when a treatment error occurs in the direction of any axis of the translation mechanism. More specifically, it can be seen that when a treatment error occurs in the X-axis direction of the translation mechanism, the difference in water equivalent thickness is larger than when a treatment error occurs in the Y-axis or Z-axis direction. On the other hand, when a treatment error occurs in the Z-axis direction of the translation mechanism, the change in the difference in water equivalent thickness due to the treatment error is small.

[0095] Figures 7(a) to (f) show examples of graphs corresponding to the three axes (X-axis, Y-axis, and Z-axis) of the translation mechanism. However, the treatment device 10 can move the bed 12 in six degrees of freedom using the translation mechanism and the rotation mechanism. In other words, the treatment device 10 can move not only in the three axes of the translation mechanism but also in the rotation angles (yaw, roll, and pitch) around the three axes of the rotation mechanism. Therefore, the presentation data processing unit 390 may generate graphs corresponding to the rotation angles around the three axes of the rotation mechanism in the same way as in Figures 7(a) to (f). Each graph shown in Figures 7(a) to (f) represents both the difference statistics for the state after the alignment process is completed (perturbation of 0.0 mm) and the difference statistics when a virtual perturbation is applied. In other words, each graph shown in Figures 7(a) to (f) simultaneously shows multiple difference statistics. However, each graph shown in Figures 7(a) to (f) may show only one of the difference statistics.

[0096] The presentation data processing unit 390 generates an image (display image) representing such information and displays it on the display device D. Figure 8 is a diagram showing an example of a display screen on the display device D where the presentation data processing unit 390 of the medical image processing device 300 displays the presentation data. Figure 8 shows an example of the display screen DS1 of the display device D where the presentation data processing unit 390 displays an image of the presentation data.

[0097] The "coronal," "sagittal," and "axial" sections shown in Figure 8 represent cross-sectional images of patient P. More specifically, "coronal" represents a coronal section (frontal section) that divides patient P into two parts in the left-right direction, namely the front (chest side) and the back (back side). In other words, it represents a cross-section viewed from directly in front of or directly behind patient P (the XY section in the room coordinate system shown in Figure 1). "Sagittal" represents a sagittal section that divides patient P into two parts in the front-back direction, namely the left and right sides. In other words, it represents a cross-section viewed from directly to the side of patient P (the XZ section in the room coordinate system shown in Figure 1). "Axial" represents a horizontal section (axial section) that divides patient P into two parts in the left-right direction, namely the upper (head side) and lower (foot side). In other words, it represents a cross-section viewed from above patient P from the head side or from above patient P from the foot side (the YZ section in the room coordinate system shown in Figure 1). The data processing unit 390 may place a corresponding cross-sectional image (which may be a difference image of the corresponding cross-section) in the central area labeled "coronal," "sagittal," or "axial" in the coronal cross-sectional image IM-C, sagittal cross-sectional image IM-S, and horizontal cross-sectional image IM-A placed on the display screen DS1.

[0098] In the coronal section image IM-C, sagittal section image IM-S, and horizontal section image IM-A, the cumulative histograms labeled "X+", "X-", "Y+", "Y-", "Z+", and "Z-" are similar to the cumulative histograms of the difference statistics shown in Figure 7. However, unlike the cumulative histogram shown in Figure 7, the cumulative histograms in the coronal section image IM-C, sagittal section image IM-S, and horizontal section image IM-A divide the virtual perturbations applied to each of the three axis directions of the translation mechanism into + and - directions. Therefore, the difference values ​​of the water equivalent thickness on the horizontal axis are not absolute values ​​but values ​​in the corresponding direction. In other words, the cumulative histograms placed in the coronal section image IM-C, sagittal section image IM-S, and horizontal section image IM-A are cumulative histograms of the difference statistics calculated by the difference calculation unit 140a, which calculates the difference image by applying the treatment error (movement error of the treatment table 12) as a virtual perturbation separately to the + and - directions for each of the three axes of the translation mechanism, and the difference statistics calculation unit 150, which calculates the error of the water equivalent thickness at each pixel of the difference image.

[0099] As shown in Figure 8, the data processing unit 390 generates an image on the display device D in which the cross-sectional images IM are arranged in a positional relationship that is easy for the user to intuitively understand, showing each cross-sectional image and the cumulative histogram corresponding to each direction (axial direction) of that cross-sectional image. This allows the user to quantitatively check the amount of change in the water equivalent thickness error in the actual position of the treatment table 12 after the alignment process has been completed, assuming a displacement due to movement error, from each image IM placed on the display screen DS1. The user can then decide whether or not to start radiation therapy based on the amount of change they have checked. More specifically, if the maximum value of the difference in water equivalent thickness in each direction shown in the coronal cross-sectional image IM-C, sagittal cross-sectional image IM-S, and horizontal cross-sectional image IM-A is within the acceptable range, the user can start radiation therapy at the current position of the treatment table 12. If it is outside the acceptable range, the user can decide, for example, to fine-tune the position of the treatment table 12 before starting radiation therapy. Fine-tuning of the position of the treatment table 12 can be done, for example, by the user operating the user interface unit (not shown).

[0100] Figure 9 shows an example of another display screen where the presentation data processing unit 390 of the medical image processing device 300 displays presentation data on the display device D. Figure 9 shows an example of switching display screen DS2 in response to user operation of the user interface unit IF. More specifically, it shows an example of switching between display screen DS2-1 and display screen DS2-2 in response to user operation of the user interface unit IF (cross keys in Figure 9).

[0101] Display screen DS2-1 is a display screen DS2 on which a cross-sectional image IM-W is the difference image between the first and second fluoroscopic images obtained when the CT image is converted to water equivalent thickness and the water equivalent thickness up to the vicinity of the tumor (PTV) is calculated by line integration considering the irradiation direction of the treatment beam B (upward in this case). The presentation data processing unit 390 may superimpose information from the treatment planning stage, such as the contour line of the tumor (GTV), onto the cross-sectional image IM-W. Display screen DS2-2 is a display screen DS2 on which a graph image IM-G is placed on which a graph of the error distribution (here, a graph similar to the histogram and cumulative histogram shown in Figure 7) is one of the difference statistics calculated by the difference statistics calculation unit 150 for the cross-sectional image IM-W. The data processing unit 390, for example, switches the display screen DS2 displayed on the display device D to display screen DS2-1 when the user presses the upper operation button on the user interface unit IF, and switches the display screen DS2 displayed on the display device D to display screen DS2-2 when the user presses the lower operation button on the user interface unit IF. This allows the user to quantitatively check the current alignment status of patient P and the amount of change in the water equivalent thickness error if a displacement due to movement error occurs from this state, based on the respective image IM placed on the display screen DS2. The user can then decide whether or not to start radiotherapy based on the checked status.

[0102] Figures 8 and 9 illustrate examples of display screens DS used by the data presentation processing unit 390 to present information to the user. However, the display screens DS used to present information to the user are not limited to those shown in Figures 8 and 9. In other words, the data presentation processing unit 390 can generate various display screens DS based on the information provided to the user and display them on the display device D.

[0103] For example, when the display screen DS2-2 shown in Figure 9 is displayed on the display device D, the data processing unit 390 may change the graphs placed in the graph image IM-G when the user presses the operation buttons on the right or left side of the user interface unit IF. More specifically, for example, when the user presses the operation buttons on the right or left side of the user interface unit IF, the data processing unit 390 may change the graphs of the three axes (X-axis, Y-axis, and Z-axis) of the translation mechanism currently placed in the graph image IM-G to graphs of the rotation angles (yaw, roll, and pitch) around the three axes of the rotation mechanism (by switching all graphs or by sequentially scrolling through the graphs one by one).

[0104] For example, when the display screen DS2-1 shown in Figure 9 is displayed on the display device D, the data processing unit 390 may enlarge the position of the tumor in the cross-sectional image IM-W if the user presses any of the operation buttons on the user interface unit IF. For example, the data processing unit 390 may further display a cursor (not shown) on the enlarged cross-sectional image IM-W and superimpose a pop-up image on the current display that shows numerical values ​​(data) such as the average, standard deviation, median, and maximum value of the pixel corresponding to the position of the cursor moved by the user using the operation buttons. For example, when the display screen DS2-2 shown in Figure 9 is displayed on the display device D, the data processing unit 390 may display a cursor (not shown) and superimpose a pop-up image on the current display that shows numerical values ​​(data) such as the average, standard deviation, median, and maximum value of the pixel values ​​of the difference image corresponding to the position of the cursor on the graph moved by the user using the operation buttons.

[0105] For example, when the data processing unit 390 displays graphs corresponding to three axes, as shown in the display screen DS2-2 in Figure 9, the user may select which graphs to display, or the data processing unit 390 may display graphs corresponding to the three axes with the largest errors. For example, in the graph image IM-G placed on the display screen DS2-2 as shown in Figure 9, the data processing unit 390 may simultaneously display graphs of the rotation angles around the three axes of the rotation mechanism instead of the upper graph (histogram). In other words, for example, the data processing unit 390 may simultaneously display cumulative histograms corresponding to all six axes that allow the bed 12 to move.

[0106] For example, the data processing unit 390 may display, in addition to or instead of, the graphs (histograms and cumulative histograms) shown in Figures 8 and 9, numerical values ​​(data) such as the average of the absolute values ​​of the pixel values ​​in the difference image, the standard deviation, the median, and the maximum value.

[0107] With this configuration, operation, and processing, the medical image processing device 300 has a position error calculation unit 370 that performs alignment processing, and a bed control unit 380 that generates a movement control signal to move the bed 12 to the treatment device 10. Furthermore, the medical image processing device 300 has a presentation data processing unit 390 that generates presentation data (for example, a display screen DS as shown in Figures 8 and 9) for the user and displays it on the display device D. As a result, the user can quantitatively judge the degree of agreement of the patient P's position in the medical image processing device 300, just as in the medical image processing device 100 and the medical image processing device 200, and can also receive assistance in deciding whether or not it is necessary to adjust the position of patient P after the alignment processing. If the user determines that the alignment processing by the medical image processing device 300 has not been performed correctly, or that it is necessary to adjust the position of patient P, the user can instruct the medical image processing device 300 to perform the alignment processing again or to adjust the position of patient P. As a result, treatment system 3 equipped with the medical image processing device 300 can perform more effective radiotherapy, similar to treatment system 1 equipped with the medical image processing device 100 and treatment system 2 equipped with the medical image processing device 200.

[0108] As described above, in the medical image processing device 300, similar to the medical image processing device 100 and the medical image processing device 200, the first image acquisition unit 110 acquires a first fluoroscopic image of patient P taken before treatment, and parameters representing the position and posture at the time the first fluoroscopic image was taken. The second image acquisition unit 120 acquires a second fluoroscopic image of patient P taken immediately before the start of treatment, and parameters representing the position and posture at the time the second fluoroscopic image was taken. Furthermore, in the medical image processing device 300, similar to the medical image processing device 100 and the medical image processing device 200, the treatment error acquisition unit 130 acquires treatment errors in radiotherapy that did not appear in the treatment planning stage. Then, in the medical image processing device 300, similar to the medical image processing device 100 and the medical image processing device 200, the difference calculation unit 140 calculates a difference image by changing the parameters representing the position and posture of the second fluoroscopic image after alignment processing based on the treatment error (by applying a virtual perturbation). Subsequently, in the medical image processing device 300, similar to the medical image processing device 100 and the medical image processing device 200, the difference statistics calculation unit 150 calculates difference statistics based on the difference image. Then, in the medical image processing device 300, similar to the medical image processing device 200, the determination unit 260 determines whether or not it is necessary to adjust the position of patient P based on the difference statistics calculated by the difference statistics calculation unit 150. Then, in the medical image processing device 300, the bed control unit 380 generates a movement control signal according to the result of the alignment process performed by the position error calculation unit 370, and moves the bed 12 to the treatment device 10. Then, in the medical image processing device 300, similar to the medical image processing device 100 and the medical image processing device 200, the presentation data processing unit 390 generates presentation data (display screen DS) to present information such as the calculated difference statistics to the user and displays it on the display device D. As a result, in the treatment system 3 equipped with the medical image processing device 300, just like in the treatment system 1 equipped with the medical image processing device 100 and the treatment system 2 equipped with the medical image processing device 200, the user can refer to the presented data (display screen DS) displayed on the display device D to determine whether the current alignment process by the medical image processing device 200 is being performed correctly.Furthermore, in the treatment system 3 equipped with the medical image processing device 300, the user can refer to the judgment result from the judgment unit 260 presented as data to determine whether or not to adjust the position of patient P.

[0109] As described above, the medical image processing device 300 further includes a position error calculation unit 370 that performs alignment processing on the medical image processing device 200 of the second embodiment, and a bed control unit 380 that generates a movement control signal to control the movement of the bed 12 of the treatment device 10 that performs radiation therapy based on the result of the alignment processing, thereby moving the bed 12. The difference calculation unit 140a calculates a difference image in which the position of the patient P captured in the second fluoroscopic image has been perturbed based on the result of the alignment processing. As a result, the medical image processing device 300 allows the bed control unit 380 to move the bed 12 of the treatment device 10 based on the amount of movement represented by the result of the alignment processing by the position error calculation unit 370.

[0110] As described above, the medical image processing device 300 further comprises a presentation data processing unit 390 that generates presentation data for presenting a first fluoroscopic image, a second fluoroscopic image, and / or a graph or numerical value based on differential statistics. This allows the medical image processing device 300 to present the presentation data generated by the presentation data processing unit 390 to the user.

[0111] In the second embodiment, a component characteristic of the second embodiment (determination unit 260) is added to the medical image processing apparatus 100 of the first embodiment, and in the third embodiment, a component characteristic of the third embodiment (position error calculation unit 370, bed control unit 380, and presentation data processing unit 390) is added to the medical image processing apparatus 200 of the second embodiment. However, the components added in each embodiment do not necessarily have to be components that need to be added. For example, the medical image processing apparatus 300 of the third embodiment may have a configuration in which the determination unit 260 added in the medical image processing apparatus 200 of the second embodiment is omitted. In this case, it becomes a medical image processing apparatus that realizes the functions of each component that the medical image processing apparatus has.

[0112] In each embodiment, a configuration was described in which the medical image processing device and the treatment device 10 are separate devices. However, the configuration in which the medical image processing device and the treatment device 10 are separate devices is not limited to this configuration; the medical image processing device and the treatment device 10 may be integrated into a single unit.

[0113] As described above, for example, a medical image processing method performed by the medical image processing device 100 is a medical image processing method in which a computer (such as a processor) acquires a first fluoroscopic image taken inside the body of patient P, acquires a second fluoroscopic image taken inside the body of patient P at a different time than the first fluoroscopic image, acquires treatment errors that occur when performing alignment processing to match the position of patient P in the second fluoroscopic image to the position of patient P in the first fluoroscopic image based on the first and second fluoroscopic images, or when treatment errors that occur in radiotherapy, applies a virtual perturbation to the position of patient P in the second fluoroscopic image based on the treatment errors, calculates a difference image between the perturbed second fluoroscopic image and the first fluoroscopic image, and calculates a difference statistic of the difference between the first fluoroscopic image and the perturbed second fluoroscopic image based on the difference image.

[0114] As explained above, for example, the program executed by the medical image processing device 100 is a program that causes a computer (such as a processor) to acquire a first fluoroscopic image taken inside the body of patient P, to acquire a second fluoroscopic image taken inside the body of patient P at a different time than the first fluoroscopic image, to acquire treatment errors that occur when performing alignment processing to match the position of patient P in the second fluoroscopic image to the position of patient P in the first fluoroscopic image based on the first and second fluoroscopic images, or when treatment errors that occur in radiotherapy, to apply a virtual perturbation to the position of patient P in the second fluoroscopic image based on the treatment errors, to calculate a difference image between the perturbed second fluoroscopic image and the first fluoroscopic image, and to calculate a difference statistic of the difference between the first fluoroscopic image and the perturbed second fluoroscopic image based on the difference image.

[0115] As explained above, for example, a storage medium storing a program executed by the medical image processing device 100 is a computer-readable non-temporary storage medium that stores a program that causes a computer (such as a processor) to acquire a first fluoroscopic image taken inside the body of patient P, to acquire a second fluoroscopic image taken inside the body of patient P at a different time than the first fluoroscopic image, to acquire treatment errors that occur when performing alignment processing to match the position of patient P in the second fluoroscopic image to the position of patient P in the first fluoroscopic image based on the first and second fluoroscopic images, or that occur in radiotherapy, to apply a virtual perturbation to the position of patient P in the second fluoroscopic image based on the treatment errors, to calculate a difference image between the perturbed second fluoroscopic image and the first fluoroscopic image, and to calculate a difference statistic of the difference between the first fluoroscopic image and the perturbed second fluoroscopic image based on the difference image.

[0116] According to at least one embodiment described above, a first image acquisition unit (110) acquires a first fluoroscopic image of the inside of a patient (P), a second image acquisition unit (120) acquires a second fluoroscopic image of the inside of a patient (P) taken at a different time than the first fluoroscopic image, a treatment error acquisition unit (130) acquires treatment errors that occur when performing alignment processing to match the position of the patient (P) in the second fluoroscopic image to the position of the patient (P) in the first fluoroscopic image based on the first and second fluoroscopic images, or when treatment errors occur during treatment (radiotherapy), and based on the treatment errors, the second fluoroscopic image is... The system includes a difference calculation unit (140) that applies a virtual perturbation to the position of the patient (P) and calculates a difference image between the perturbed second fluoroscopic image (second P fluoroscopic image) and the first fluoroscopic image, and a difference statistics calculation unit (150) that calculates a difference statistic (difference statistic) between the first fluoroscopic image and the perturbed second fluoroscopic image (second P fluoroscopic image) based on the difference image. This allows a physician or other radiation therapist (user) to quantitatively confirm the results of the patient (P) positioning by image matching between CT images (first fluoroscopic image and second fluoroscopic image) taken during treatment planning and during the treatment phase.

[0117] 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. [Explanation of Symbols]

[0118] 1,2,3...Treatment system, 10...Treatment device, 12...Treatment table, 14...CT scanning device, 16...Treatment beam irradiation gate, 100,200,300...Medical image processing device, 110...First image acquisition unit, 120...Second image acquisition unit, 130...Treatment error acquisition unit, 140...Difference calculation unit, 150...Difference statistics calculation unit, 260...Determination unit, 370...Position error calculation unit, 380...Treatment table control unit, 390...Presentation data processing unit, D...Display device

Claims

1. A first image acquisition unit that acquires a first fluoroscopic image of the inside of the patient's body, A second image acquisition unit acquires a second fluoroscopic image of the patient's body taken at a different time than the first fluoroscopic image, A treatment error acquisition unit that acquires treatment errors that occur when performing alignment processing to match the position of the patient as depicted in the second fluoroscopic image to the position of the patient as depicted in the first fluoroscopic image, based on the first fluoroscopic image and the second fluoroscopic image, or when acquiring treatment errors that occur during treatment, A difference calculation unit that modifies parameters representing the position and posture of the patient as captured in the second fluoroscopic image based on the treatment error to introduce a virtual shift, and calculates a difference image between the second fluoroscopic image with the shift and the first fluoroscopic image, A difference statistics calculation unit calculates a difference statistic between the first perspective image and the second perspective image with the displacement applied, based on the difference image. A medical image processing device equipped with [a specific feature].

2. The difference calculation unit modifies the parameters representing the position and posture of the patient as captured in the second fluoroscopic image to provide multiple stages of the displacement, and calculates the difference image for each of the provided displacements. The difference statistics calculation unit calculates the statistics corresponding to each of the differences based on each of the difference images. The medical image processing apparatus according to claim 1.

3. The system further includes a determination unit that determines the result of the alignment process based on the aforementioned statistical quantity. A medical image processing apparatus according to claim 1 or claim 2.

4. A position error calculation unit that performs the aforementioned alignment process, Based on the results of the alignment process, a bed control unit generates a movement control signal to control the movement of the treatment bed of the treatment device, and moves the treatment bed. Furthermore, The difference calculation unit calculates the difference image with the displacement applied by changing the parameters representing the position and posture of the patient as captured in the second fluoroscopic image based on the result of the alignment process. A medical image processing apparatus according to any one of claims 1 to 3.

5. The system further comprises a presentation data processing unit that generates presentation data for presenting a first perspective image, a second perspective image, and / or a graph or numerical value based on the statistical quantity, A medical image processing apparatus according to any one of claims 1 to 4.

6. The aforementioned difference image is an image showing the path of radiation irradiated to the patient during treatment. A medical image processing apparatus according to any one of claims 1 to 5.

7. The aforementioned treatment error is a movement error that is expected to occur when the treatment table of the treatment device is moved for treatment purposes. A medical image processing apparatus according to any one of claims 1 to 6.

8. The aforementioned statistics are calculated based on the direction of radiation irradiation to the patient during treatment, and the difference image of the range based on the spatial positional relationship between the irradiation area and the tumor area present in the patient's body. A medical image processing apparatus according to any one of claims 1 to 7.

9. A medical image processing apparatus according to any one of claims 1 to 8, A treatment device comprising: an irradiation unit for irradiating the patient with radiation; an imaging device for capturing the first fluoroscopic image and the second fluoroscopic image; and a bed for supporting and securing the patient. A treatment system equipped with [the following features].

10. Computers First fluoroscopic images were taken of the inside of the patient's body. A second fluoroscopic image of the patient's body, taken at a different time than the first fluoroscopic image, is obtained. When performing a positioning process to match the position of the patient as depicted in the second fluoroscopic image to the position of the patient as depicted in the first fluoroscopic image, based on the first fluoroscopic image and the second fluoroscopic image, treatment errors that occur during treatment are acquired. Based on the aforementioned treatment error, parameters representing the position and posture of the patient as captured in the second fluoroscopic image are changed to introduce a virtual shift, and a difference image is calculated between the second fluoroscopic image with the shift and the first fluoroscopic image. Based on the difference image, a statistical value of the difference between the first perspective image and the second perspective image with the displacement applied is calculated. Medical image processing methods.

11. On the computer, The first fluoroscopic image was taken from inside the patient's body. A second fluoroscopic image of the patient's body, taken at a different time than the first fluoroscopic image, is obtained. When performing a positioning process to match the position of the patient as depicted in the second fluoroscopic image to the position of the patient as depicted in the first fluoroscopic image, based on the first fluoroscopic image and the second fluoroscopic image, the system acquires treatment errors that occur during treatment. Based on the aforementioned treatment error, parameters representing the patient's position and posture as captured in the second fluoroscopic image are changed to introduce a virtual shift, and a difference image is calculated between the second fluoroscopic image with the shift and the first fluoroscopic image. Based on the difference image, calculate the statistical difference between the first perspective image and the second perspective image with the displacement applied. program.

12. On the computer, The first fluoroscopic image was taken from inside the patient's body. A second fluoroscopic image of the patient's body, taken at a different time than the first fluoroscopic image, is obtained. When performing a positioning process to match the position of the patient as depicted in the second fluoroscopic image to the position of the patient as depicted in the first fluoroscopic image, based on the first fluoroscopic image and the second fluoroscopic image, the system acquires treatment errors that occur during treatment. Based on the aforementioned treatment error, parameters representing the patient's position and posture as captured in the second fluoroscopic image are changed to introduce a virtual shift, and a difference image is calculated between the second fluoroscopic image with the shift and the first fluoroscopic image. Based on the difference image, calculate the statistical difference between the first perspective image and the second perspective image with the displacement applied. A computer-readable, non-temporary storage medium that stores a program.

Images