JP2017225487A - Radiotherapy support system, image generation method, and image generation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiotherapy support system, an image generation method, and an image generation program which reduce burden on a patient and is capable of speedily and accurately positioning the patient during radiotherapy.SOLUTION: A radiotherapy support system comprises: an associating unit which associates the positions of bones and joints of a patient with the positions of respective portions of a human body model representing the body surface and inside of the patient; and an image generation unit which, on the basis of a result of association by the associating unit, generates an image in which the respective portions of the human body model have been moved in accordance with the positions of the bones and joints of the patient at the time of radiotherapy.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radiation therapy support system, an image generation method, and an image generation program.

  Conventionally, in conventional radiotherapy in which radiation (X-rays) is applied to a tumor part (cancer) of a patient for treatment, usually several to 40 divided irradiations are performed over a plurality of days. In radiotherapy, a high dose can be concentrated on a tumor site due to the characteristics of radiation, but more accurate positioning is required. That is, it is desirable that the patient position for each radiotherapy is constant, and it is necessary to accurately determine the position of the patient with respect to the radiation. For such patient positioning (also referred to as “patient setup”), a body surface marker (for example, ink) is used as an index for knowing the position of the tumor.

  The body surface marker is drawn on the patient's body surface according to the following flow. First, a computed tomography image (CT image) for treatment planning is acquired using a tomography apparatus (for example, an X-ray CT (Computed Tomography) apparatus). Next, after identifying the position and shape of the tumor part based on the obtained CT image, the contour of the tumor part or normal organ is input on the computer, the radiation direction and position are determined, and treatment is performed. A plan is created, and a pseudo X-ray image, which is a fluoroscopic image of a patient viewed from the generation point of radiation, is created. The pseudo X-ray image is the most basic index for patient positioning. For example, pseudo X-ray images are created in two directions from above and from the side of a patient in addition to the radiation incident direction during treatment, and are recorded and stored in a recording device.

  At the time of actual radiotherapy, the doctor / engineer compares the X-ray image (hereinafter referred to as “positioning X-ray image”) taken with the radiotherapy apparatus with the pseudo X-ray image, and determines the patient position and irradiation area. Visually confirm that they match. Then, in the matched patient position, a body surface marker is drawn on the patient's body surface by a laser indicator (projector) installed in the radiation treatment room based on the projection marker projected on the patient's body surface. If the patient's body position and irradiation area do not match, finely adjust the patient's body position by moving the treatment table, etc., and again take a positioning X-ray image and compare it with the pseudo X-ray image. To do. Such work is repeated until the positioning X-ray image and the pseudo X-ray image coincide with each other, and a body surface marker is drawn.

  Thereafter, positioning is performed at the time of actual radiotherapy. Specifically, by moving the treatment table by visual operation or moving the patient's body position so that the body surface marker and the projected marker projected onto the patient's body surface by the laser indicator coincide. Perform patient positioning.

  In addition, as a technique related to radiotherapy, the movement of the treatment target part is directly observed in real time using X-ray fluoroscopy and ultrasound, and the irradiation of radiation is controlled based on the movement vector of the directly observed treatment target part. (See, for example, Patent Documents 1 and 2).

JP 2005-185336 A Japanese Patent Laid-Open No. 2003-1117010

  However, body surface markers drawn on the patient's body surface can easily move due to differences in limb position and sagging skin, and the tilt and twist of the body axis, the position and angle of the arms and legs relative to the trunk. Since the reproducibility is limited, there is a problem that the position and shape of the tumor part at the time of treatment planning differ at the time of radiation treatment, and there is a possibility that patient positioning errors may occur. Therefore, at present, there has been a problem that the radiation irradiation range has to be enlarged in advance by the amount of positioning error that can occur.

  In recent years, a method of positioning a patient by acquiring a positioning X-ray image (or CT image) for each radiotherapy and comparing it with a pseudo X-ray image has been implemented. Since there is no change in positioning, there is still a possibility that a patient positioning error will occur. Moreover, when acquiring the X-ray image for positioning, there exists a problem that a patient's X-ray exposure generate | occur | produces for every acquisition. Furthermore, if the number of times of acquisition of the positioning X-ray image increases until the patient body position and the irradiation region coincide with each other by comparing the positioning X-ray image and the pseudo X-ray image, the time required for positioning the patient accordingly And the patient's X-ray exposure dose increases.

  An object of the present invention is to provide a radiation therapy support system, an image generation method, and an image generation program capable of reducing the burden on a patient and performing patient positioning in a short time and with high accuracy during radiation therapy. .

The radiation therapy support system according to the present invention includes:
An association unit that associates the position of the patient's skeleton and joints with the position of each part of the human body model simulating the patient's body surface and interior;
An image generation unit that generates an image obtained by moving each part of the human body model according to the position of the skeleton and joints of the patient at the time of radiation treatment based on the result of the association by the association unit;
Prepare.

An image generation method according to the present invention includes:
Correlate the position of the patient's skeleton and joints with the position of each part of the human body model that imitates the patient's body surface and interior,
Based on the result of the association, an image is generated by moving each part of the human body model in accordance with the positions of the skeleton and joints of the patient at the time of radiation therapy.

An image generation program according to the present invention includes:
On the computer,
A process for associating the position of the patient's skeleton and joints with the position of each part of the human body model imitating the patient's body surface and interior;
Processing for storing the result of the association;
A process for generating an image in which each part of the human body model is moved in accordance with the position of the skeleton and joints of the patient at the time of radiotherapy based on the stored result of the correspondence;
Is executed.

  According to the present invention, it is possible to reduce the burden on the patient during radiotherapy and to perform positioning of the patient including the twist of the body axis and the angles of the limbs in a short time and with high accuracy.

It is a figure which shows the structure of the radiation therapy assistance system in this Embodiment. It is a figure which shows the structure of the examination room and radiotherapy room in this Embodiment. It is a figure which shows the example of the skeleton model in this Embodiment. It is a figure which shows the example of the human body model in this Embodiment. It is a figure which shows a mode that the patient in the radiotherapy room on real space is reproduced on virtual space. It is a figure which shows the example of a display of the X-ray image for a comparison in this Embodiment. It is a flowchart which shows the production | generation operation | movement of the X-ray image for a comparison in this Embodiment.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating an example of a configuration of a radiation therapy support system 1 in the present embodiment. FIG. 2 is a diagram illustrating an example of a configuration of an examination room and a radiation therapy room in the present embodiment.

  As shown in FIG. 1, the radiation therapy support system 1 includes a first detection unit 10, a CT apparatus 12 (corresponding to the “CT image generation unit” of the present invention), a treatment planning apparatus 14, a second detection unit 20, and a comparison. An X-ray image generation apparatus 30 and a radiation therapy apparatus 50 are provided.

  As shown in FIGS. 1 and 2, the first detection unit 10, the CT apparatus 12, and the patient bed 60 are installed in an examination room that performs various examinations. The treatment planning device 14 is installed in a treatment planning room for creating a treatment plan for performing radiation treatment. The second detection unit 20, the comparative X-ray image generation apparatus 30, the radiotherapy apparatus 50, and the treatment table 80 are installed in a radiotherapy room that performs radiotherapy. Note that the comparative X-ray image generation apparatus 30 may be installed in an examination room or a treatment planning room instead of the radiation treatment room.

  The first detection unit 10 detects a patient 70 placed on the patient bed 60 in the same position as that during radiotherapy in the examination room. In the present embodiment, as shown in FIG. 2A, the first detection unit 10 is a distance image sensor attached to, for example, the ceiling of the examination room, and images the patient 70 and the imaging range from the first detection unit 10. The distance (depth) to the patient 70 existing inside is measured. Then, the first detection unit 10 transmits the detection result (captured image, distance information) to the comparative X-ray image generation device 30.

  The CT apparatus 12 irradiates the patient 70 with X-rays while rotating 360 degrees around the patient 70, images the cross-section of the patient 70 placed on the patient bed 60 in the same posture as during radiotherapy, and from each direction A CT image of the patient 70 is generated by processing the captured image of the patient 70 with a computer. The CT apparatus 12 transmits the generated CT image to the treatment planning apparatus 14 and the comparative X-ray image generation apparatus 30.

  The treatment planning apparatus 14 has a function of simulating the radiation dose distribution in the patient 70 by numerical calculation based on the in-vivo information of the patient 70 obtained from the CT image transmitted from the CT apparatus 12. An operator (an operator who plans a treatment plan) refers to the calculation result of the treatment planning device 14 to determine an irradiation condition such as an optimum irradiation direction, energy, irradiation position, and irradiation amount of the radiation. Formulate. The treatment planning device 14 transmits treatment plan information indicating the treatment plan formulated by the operator to the comparative X-ray image generation device 30.

  The second detection unit 20 detects the patient 70 placed on the treatment table 80 in the same position as that during radiation treatment in the radiation treatment room. In the present embodiment, as shown in FIG. 2B, the second detection unit 20 is a distance image sensor attached to, for example, the ceiling of the radiotherapy room, and images the patient 70 and images from the second detection unit 20. The distance (depth) to the patient 70 existing within the range is measured. Then, the second detection unit 20 transmits the detection result (captured image, distance information) to the comparative X-ray image generation device 30 and the radiotherapy device 50.

  In FIG. 2B, the rotation trajectory when the gantry of the radiation therapy apparatus 50 rotates is indicated by a dotted line G. In this case, the rotation center of the radiation therapy apparatus 50 is called an isocenter.

  The comparative X-ray image generation apparatus 30 is an X-ray image generated based on the CT image generated by the CT apparatus 12 when the patient 70 is positioned when performing radiation therapy on the patient 70. Specifically, a comparative X-ray image used for comparison with a pseudo X-ray image that is a fluoroscopic image of the patient 70 viewed from the generation point of radiation is generated.

  At the time of actual radiotherapy, the doctor / engineer visually compares the comparative X-ray image generated by the comparative X-ray image generation device 30 with the pseudo X-ray image, and the patient's body position and the irradiation region match. Make sure.

  If the patient position and the irradiation region do not match, the patient position and the irradiation region are finely adjusted by moving the treatment table 80 or the patient 70 itself, etc., and again generated by the comparative X-ray image generation device 30. The comparison X-ray image and the pseudo X-ray image are compared. This comparison operation is repeated until the comparison X-ray image and the pseudo X-ray image match. When the doctor / engineer confirms that the comparative X-ray image matches the pseudo X-ray image, the positioning operation of the patient 70 is terminated.

  The radiotherapy apparatus 50 performs radiotherapy for the patient 70 placed on the treatment table 80 based on the treatment plan information transmitted from the treatment planning apparatus 14 after the positioning operation of the patient 70 is completed. The radiation therapy apparatus 50 includes a rotation mechanism that rotates 360 degrees around the patient 70 and that can irradiate radiation (treatment beam) from an arbitrary angle. The radiation therapy apparatus 50 may perform cyber knife therapy, tomotherapy, heavy particle therapy, or the like on the patient 70.

  Next, a specific configuration of the comparative X-ray image generation apparatus 30 will be described. As shown in FIG. 1, the comparative X-ray image generation apparatus 30 includes a first skeleton model generation unit 32, a human body model generation unit 34, an alignment unit 36, a second skeleton model generation unit 38, a human body model movement unit 40, A comparison X-ray image generation unit 42 and a comparison X-ray image display unit 44 are provided.

  The first skeleton model generation unit 32, the human body model generation unit 34, and the alignment unit 36 correspond to the “association unit” of the present invention. The second skeleton model generating unit 38, the human body model moving unit 40, and the comparative X-ray image generating unit 42 correspond to the “image generating unit” of the present invention. The comparative X-ray image display unit 44 corresponds to the “image display unit” of the present invention.

  Although not shown, the comparative X-ray image generation apparatus 30 includes, for example, a ROM (corresponding to the “image generation program” of the present invention), a processor such as a CPU (Central Processing Unit) as a processor, and a control program. It has a storage medium such as a read only memory (RAM), a working memory such as a random access memory (RAM), and a communication circuit. In this case, the function of each unit described above is realized by the processor executing the control program.

  The first skeleton model generation unit 32 generates a first skeleton model that imitates the skeleton and joints of the patient 70 based on the detection result of the first detection unit 10. Then, the first skeleton model generation unit 32 outputs the generated first skeleton model to the alignment unit 36.

  The first skeleton model generation unit 32 can generate the first skeleton model using a known method for generating a skeleton model from motion capture data, for example. The motion capture data can be obtained by using various motion capture techniques such as a video motion capture using an image in addition to a motion capture using an exclusive marker (optical, magnetic, mechanical, etc.).

  FIG. 3 is a diagram illustrating an example of a skeleton model in the present embodiment. As shown in FIG. 3, the skeleton model is composed of a plurality of joints, and each joint is connected in a tree structure. A line connecting each joint corresponds to a bone in the human body and is generally called a bone. Subscripts A to K are joints indicating the waist, hip joint, knee joint, ankle joint, center of the spine, upper spine, shoulder joint, elbow joint, wrist joint, finger joint, and neck, respectively. Each joint has three-dimensional position information and information on tilt (rotation).

  Arrows connecting the joints indicate a parent-child relationship. In other words, the elbow joint of the subscript H is a child of the shoulder joint of the subscript G, and the wrist joint of the subscript I is a child of the elbow joint H, indicating that it becomes a child as it goes from the trunk to the extermination joint. Yes. It should be noted that the number of joints in the skeletal model may be selected appropriately depending on the irradiation site of the radiation and the like, and the skeleton model only needs to have a data structure that changes from parent to child as it goes to deletion.

  The human body model generation unit 34 generates a human body model simulating the body surface and the inside of the patient 70 based on the CT image transmitted from the CT apparatus 12. In this embodiment, the human body model is a mesh model in which the body surface and the inside are represented by a mesh. Then, the human body model generation unit 34 outputs the generated human body model to the alignment unit 36.

  The human body model is created from the CT image transmitted from the CT apparatus 12 and the outline information (for example, DICOM RT-Structure set) of tissues and organs obtained at the time of treatment planning using the treatment planning apparatus 14.

  More specifically, the human body model is generated by, for example, using a marching cube method in which a cube including an isosurface is extracted from voxel data labeled with contour information, and the isosurface included in the cube is approximated by a triangle. Is done. The contour information can be created by contour extraction using the CT value (pixel value) threshold by the treatment planning device 14 or by manual input. Note that the contour extraction and manual input using the CT value threshold may be performed on other image software capable of reading a CT image.

  FIG. 4 is a diagram illustrating an example of a human body model represented by a mesh in the present embodiment. FIG. 4 shows a human body model including a body surface and bones that are frequently used for positioning the patient 70. In the treatment plan, in addition to the body surface, bones, and lungs, other organs and tumors (targets) are often surrounded. Therefore, the positioning operation of the patient 70 can be facilitated by generating a human body model including these tumor parts and other organs.

  In addition, since the positioning index of the useful patient 70 changes according to the irradiation site | part etc. of a radiation, the structure | tissue and organ contained in a human body model should just be selected appropriately according to an irradiation site | part etc. Further, as shown in FIG. 4, the material assigned to the mesh model is given transparency. This is because it is possible to generate a virtual X-ray image for comparison by allowing information inside the body to be obtained from the appearance like an X-ray fluoroscopic image.

  The alignment unit 36 uses the predetermined reference (a marker to be described later) included in both the detection result and the CT image respectively transmitted from the first detection unit 10 and the CT apparatus 12, from the first skeleton model generation unit 32. The output skeleton and joint positions of the first skeletal model are associated with the positions of the respective parts of the human body model output from the human body model generation unit 34 so that their positions match. Then, the alignment unit 36 outputs the first skeleton model and the human body model obtained as a result to the human body model moving unit 40.

  The first skeleton model and the human body model have different coordinate systems because they are obtained by different configurations (first detection unit 10 and CT apparatus 12). Therefore, the alignment unit 36 performs the above association by converting the coordinate system of the first skeleton model into the coordinate system of the human body model by the following procedure. This association is performed by attaching a detection result (captured image) transmitted from each of the first detection unit 10 and the CT apparatus 12 and a marker detectable in the CT image to the body surface of the patient 70.

  Specifically, the position on the body surface of the patient 70 (front surface if facing up) that can capture micro metal balls (four or more in this embodiment) as markers with the first detection unit 10 (distance image sensor). To obtain the coordinate value of the marker.

  Then, the alignment unit 36 calculates a three-dimensional movement amount between the marker coordinates imaged by the first detection unit 10 and the marker coordinates obtained from the CT image. Thereafter, the alignment unit 36 converts the coordinate system of the first skeleton model into the coordinate system of the human body model by reflecting the calculated three-dimensional movement amount on the position information of the first skeleton model, and thereby the first skeleton model. The positions of the skeletons and joints of the human body model and each part of the human body model are associated with each other so that their positions are matched.

  For example, a procrustes analysis can be applied to the calculation of the three-dimensional movement amount. In this case, the alignment unit 36 calculates the three-dimensional movement amount by obtaining an approximate solution that minimizes the square sum of the difference between the marker coordinates imaged by the first detection unit 10 and the marker coordinates obtained from the CT image. To do. After the association, the first skeleton model and the human body model are parented into a data structure having the first skeleton model as a parent and the human body model as a child.

  The second skeletal model generation unit 38 uses the same method as the first skeletal model generation unit 32 based on the detection result transmitted from the second detection unit 20 to simulate the skeleton and joints of the patient 70. Generate a skeletal model. Then, the second skeleton model generation unit 38 outputs the generated second skeleton model to the human body model moving unit 40.

  The human body model moving unit 40 includes a skeleton and a joint corresponding to the second skeleton model output from the second skeleton model generation unit 38 in the positions of the skeleton and the joint corresponding to the first skeleton model output from the alignment unit 36. Each part of the human body model associated with the first skeleton model is moved by the alignment unit 36 so as to coincide with the position of the human body model. Then, the human body model moving unit 40 outputs the human body model obtained by moving each unit to the comparative X-ray image generating unit 42.

  In the present embodiment, a comparative X-ray image for comparison with a pseudo X-ray image at the time of positioning of the patient 70 by moving each part of the human body model based on the second skeletal model obtained at the time of radiotherapy. Is generated. Therefore, it is necessary to determine how to move the vertex of the human body model when the position of the skeleton and joint corresponding to the first skeleton model does not match the position of the skeleton and joint corresponding to the second skeleton model. . This determination operation is generally called skinning.

  Skinning groups each bone (joint) and each vertex of the human body model mesh. Each vertex can belong to a plurality of groups, and can follow the movement of a plurality of bones. Which bones follow at what rate is defined by the weight per vertex.

  In moving each part of the human body model so that the positions of the skeleton and the joint corresponding to the first skeleton model coincide with the positions of the skeleton and the joint corresponding to the second skeleton model, first, in the real space of the radiotherapy room The geometric arrangement (see FIGS. 5A and 5C) is reproduced in the virtual space (see FIGS. 5B and 5D).

  Specifically, the position and orientation (orientation) of the second detection unit 20 in the coordinate system in the real space with the isocenter (center of the gantry rotation trajectory G) as the origin is obtained, and the position and orientation are obtained in the virtual space. Defined in Here, since the 2nd detection part 20 can acquire the 3D coordinate data of the object centering on the 2nd detection part 20, the 3D coordinate data of the object in the radiotherapy room measured in advance and From the correspondence with the three-dimensional coordinate data of the object acquired from the second detection unit 20, the position and orientation of the second detection unit 20 can be obtained.

  As a method for deriving the position and orientation, for example, Orthogonal Procedures Problem method is used. In addition, the association between the three-dimensional coordinate position in the radiation therapy room and the three-dimensional point group acquired from the second detection unit 20 can be performed using a three-dimensional feature amount such as a SHOT feature amount.

  In addition, since the 2nd detection part 20 (distance image sensor) can acquire image data, the position of the 2nd detection part 20 is obtained by changing the position of a known pattern image (for example, chess board) and photographing several. You may ask for attitude. In this way, the position and orientation of the second detection unit 20 can be obtained by various methods, and a method suitable for the second detection unit 20 to be used may be used.

  Here, the second detection unit 20 in the real space illustrated in FIG. 5A is used to acquire the second skeletal model of the patient 70. Further, the position of the second detection unit 20 ′ defined in the virtual space is used as a reference when placing the human body model 100. Then, by arranging the positions of the skeleton and joints of the second skeleton model at the positions of the skeleton and joints of the first skeleton model, the position of the patient 70 in the real space can be reproduced in the virtual space.

  Further, the three-dimensional position and angle of the human body model 100 in the virtual space are arbitrary joints among the first skeleton models parented as the parent of the human body model 100 (in the case of the first skeleton model shown in FIG. It is determined by the three-dimensional coordinates of the waist) corresponding to the subscript A and the rotation angle information. Only the rotation angle is used for the other joints, and each part of the human body model 100 can be moved by reflecting the rotation angle on the rotation angle of each joint of the first skeleton model. As described above, in the present embodiment, the position and posture of the patient 70 in the real space are reproduced on the virtual space by the skeletal animation.

  Skeletal animation is a technique used for computer animation of characters, also called bone animation or skinned mesh animation. In skeletal animation, a predetermined posture (key frame) is expressed by a skeleton that is a hierarchical connection of skeletons (bones), and the position of the component points that make up the character's body surface is tracked accordingly. Realize animation.

  The comparative X-ray image generating unit 42 generates a comparative X-ray image based on the human body model output from the human body model moving unit 40 and the treatment plan information transmitted from the treatment planning device 14. The comparison X-ray image generation unit 42 can generate a plurality of comparison X-ray images viewed from a plurality of directions. Then, the comparison X-ray image generation unit 42 outputs the generated comparison X-ray image to the comparison X-ray image display unit 44.

  Here, in order to generate a comparative X-ray image, a virtual position on the gantry rotation trajectory G ′ is used with reference to the position of the isocenter (center of the gantry rotation trajectory G ′, see FIG. 5B) defined in the virtual space. A typical camera as a virtual camera. The position and number of virtual cameras to be arranged can be arbitrarily selected. As an angle of the virtual camera, an angle in the radiation irradiation direction is generally selected. However, when there is no irradiation direction on the front side (gantry angles 0 °, 180 °) and side surfaces (gantry angles 90 °, 270 °), these angles are often additionally selected.

  In the present embodiment, when the comparison X-ray image generation unit 42 generates a comparison X-ray image corresponding to the radiation irradiation direction, the collimator angle included in the treatment plan information transmitted from the treatment planning device 14, A radiation irradiation region is depicted with reference to the JAW position and the multi-division collimator position. The comparison X-ray image generation unit 42 generates a comparison X-ray image by perspective projection viewed from the position of the virtual camera.

  The comparison X-ray image display unit 44 displays the comparison X-ray image output from the comparison X-ray image generation unit 42 using the treatment plan information transmitted from the treatment planning device 14. When a plurality of comparison X-ray images viewed from a plurality of directions are output from the comparison X-ray image generation unit 42, the comparison X-ray image display unit 44 simultaneously displays the plurality of comparison X-ray images. be able to.

  FIG. 6 is a diagram showing a display example when the comparative X-ray image in the present embodiment is displayed at the same time. FIG. 6 shows a front image, a side image, and an image viewed from the right front obliquely from the left in the drawing. The comparative X-ray images 200, 210, and 220 shown at the top are display examples before the positioning of the patient 70 is started. The comparative X-ray images 206, 216, and 226 shown at the bottom are display examples when the positioning of the patient 70 is completed. Further, comparative X-ray images 202, 204, 212, 214, 222, and 224 shown between the uppermost stage and the lowermost stage are display examples during positioning of the patient 70.

  Before the positioning of the patient 70 is started, since the patient 70 is not located near the isocenter, only the scaler is displayed on the comparative X-ray images 200 and 210. In addition, in the comparative X-ray image 220, a scaler and a frame of an X-ray irradiation region included in the treatment plan information transmitted from the treatment planning device 14 are displayed.

  The second-stage comparative X-ray images 202, 212, and 222 are images when the patient 70 is located near the isocenter. In the display example shown in FIG. 6, it is assumed that there is a deviation in the head-to-tail direction of the patient 70 and the rotation of the body in a visual comparison with a pseudo X-ray image (not shown). In this case, the position or body position of the patient 70 is corrected.

  The third-stage comparative X-ray images 204, 214, and 224 are images after correcting the head-to-tail direction and body rotation of the patient 70. In the display example illustrated in FIG. 6, it is assumed that the position of the left arm of the patient 70 is shifted in visual comparison with a pseudo X-ray image (not shown). The lowermost comparison X-ray images 206, 216 and 226 are images when the position of the left arm of the patient 70 is corrected and the positioning operation of the patient 70 is completed.

  Next, with reference to the flowchart shown in FIG. 7, a comparison X-ray image generation operation in the present embodiment will be described.

  First, the first skeleton model generation unit 32 generates a first skeleton model imitating the skeleton and joints of the patient 70 based on the detection result of the first detection unit 10 (step S100).

  Next, the human body model generation unit 34 generates a human body model that imitates the body surface and the inside of the patient 70 based on the CT image generated by the CT apparatus 12 (step S120).

  Next, the alignment unit 36 is generated by the first skeleton model generation unit 32 using a predetermined reference included in both the detection result of the first detection unit 10 and the CT image generated by the CT apparatus 12. The positions of the skeleton and joints of the first skeleton model thus made correspond to the positions of the respective parts of the human body model generated by the human body model generation unit 34 (step S140).

  Next, the second skeleton model generation unit 38 generates a second skeleton model imitating the skeleton and joints of the patient 70 based on the detection result of the second detection unit 20 (step S160).

  Next, the human body model moving unit 40 uses the skeleton and joints of the second skeleton model generated by the second skeleton model generation unit 38 so that the positions of the skeleton and joints of the first skeleton model associated by the alignment unit 36 are the same. Each part of the human body model associated with the first skeletal model is moved so as to coincide with the position (step S180).

  Finally, the comparative X-ray image generation unit 42 generates a comparative X-ray image based on the human body model moved by the human body model moving unit 40 and the treatment plan information generated by the treatment planning device 14. (Step S200). When the process of step S200 is completed, the generation operation of the comparative X-ray image ends.

  The comparative X-ray image generated here is used for comparison with a pseudo X-ray image that is a fluoroscopic image of the patient 70 viewed from the radiation generation point.

  As described above in detail, in the present embodiment, the radiation therapy support system 1 detects the patient 70 placed on the patient bed 60 when creating a treatment plan for performing radiation therapy by irradiating radiation. The first skeleton model generating unit 32 that generates a first skeleton model imitating the skeleton and joints of the patient 70 based on the detection result of the first detecting unit 10 and the CT of the patient 70 when creating a treatment plan Based on the CT image generated by the CT apparatus 12 (CT image generation unit) that generates the image, the human body model generation unit 34 that generates a human body model imitating the body surface and the inside of the patient 70, the detection result, and Using a predetermined reference included in both of the CT images, an alignment unit 36 that associates the position of the skeleton and joints of the first skeleton model with the position of each part of the human body model, A second skeleton that generates a second skeleton model that imitates the skeleton and joints of the patient 70 based on the detection result of the second detection unit 20 that detects the patient placed on the treatment table 80 when performing the radiation therapy. Each part of the human body model associated with the first skeleton model so that the position of the skeleton and joint corresponding to the first skeleton model matches the position of the skeleton and joint corresponding to the second skeleton model. Based on the CT image when positioning the patient 70 when performing radiation therapy on the patient 70 based on the human body model moving unit 40 that moves the human body model and the human body model moved by the human body model moving unit 40 A comparison X-ray image generation unit 42 that generates a comparison X-ray image used for comparison with the generated X-ray image (pseudo X-ray image).

  According to the present embodiment configured as described above, each part of the human body model 100 is moved based on the second skeletal model obtained at the time of radiotherapy, and compared with the pseudo X-ray image when the patient 70 is positioned. An X-ray image for comparison is generated. This makes it possible to reduce the patient's X-ray exposure, unlike the conventional case where the patient's X-ray exposure occurs every time a positioning X-ray image for comparison with a pseudo X-ray image is acquired. Conventionally, in order to obtain an X-ray image for positioning, that is, an X-ray photograph, it has been necessary to leave the radiation treatment room and take an image, but in this embodiment, an X-ray image for comparison is generated in real time. Since it is displayed and can be confirmed by the doctor, the patient can be positioned in a short time including the twist of the body axis and the angle of the limbs.

  Further, conventionally, there has been a possibility that a positioning error of the patient may occur between the treatment planning time and the radiation treatment time because the body surface marker drawn on the patient's body surface easily moves. In this embodiment, since a comparative X-ray image that reflects the position of the patient's body is generated based on information obtained both during treatment planning and during radiation treatment, patient positioning accuracy is improved. Can be made. It is also possible to eliminate the need to draw a body surface marker on the patient's body surface for patient positioning.

  Furthermore, by simultaneously displaying a comparative X-ray image viewed from a plurality of directions in real time, a doctor can compare a comparative X-ray image and a pseudo X-ray image in a plurality of directions at a time. In addition to shortening the positioning time, positioning accuracy can be improved. As described above, during radiation therapy, the X-ray exposure dose of the patient 70 can be reduced, and the patient 70 can be positioned in a short time with high accuracy. In addition, since X-ray irradiation is not necessary, the patient can be positioned in a separate room. If an apparatus having a mechanism for carrying the patient 70 after positioning to the radiation treatment room by a robot arm or the like is used, the use time of the radiation treatment room per patient can be further shortened.

  In the above embodiment, an example in which the CT apparatus 12 is installed in the examination room has been described. However, an MRI apparatus may be installed together with the CT apparatus 12 or instead of the CT apparatus 12. In this case, the MRI apparatus generates an MRI image of the patient 70 corresponding to the CT image generated by the CT apparatus 12.

  Each of the above-described embodiments is merely an example of the implementation of the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

  INDUSTRIAL APPLICABILITY The present invention is useful as a radiation therapy support system, an image generation method, and an image generation program that can reduce the burden on a patient and perform patient positioning in a short time and with high accuracy during radiotherapy.

DESCRIPTION OF SYMBOLS 1 Radiotherapy support system 10 1st detection part 12 CT apparatus 14 Treatment plan apparatus 20,20 '2nd detection part 30 X-ray image generation apparatus for comparison 32 1st skeleton model generation part 34 Human body model generation part 36 Positioning part 38 Second skeleton model generation unit 40 Human body model moving unit 42 Comparison X-ray image generation unit 44 Comparison X-ray image display unit 50 Radiation therapy device 60 Patient bed 70 Patient 80 Treatment table 100 Human body model 200, 202, 204, 206, 210, 212, 214, 216, 220, 222, 224, 226 X-ray image for comparison G, G 'gantry rotation orbit

Claims (7)

An association unit that associates the position of the patient's skeleton and joints with the position of each part of the human body model simulating the patient's body surface and interior;
An image generation unit that generates an image obtained by moving each part of the human body model according to the position of the skeleton and joints of the patient at the time of radiation treatment based on the result of the association by the association unit;
Radiation therapy support system provided. The association unit includes
When taking a CT image for creating a treatment plan for performing radiation therapy by irradiating with radiation, the patient is detected based on the detection result of the first detection unit that detects the patient placed on the patient bed. A first skeleton model generation unit that generates a first skeleton model imitating the skeleton and joints of
A human body model generation unit that generates the human body model based on a CT image generated by a CT image generation unit that generates a CT image of the patient when creating the treatment plan;
An alignment unit that associates the position of the skeleton and joints of the first skeleton model with the position of each part of the human body model using a predetermined reference included in both the detection result and the CT image; ,
The radiation therapy support system according to claim 1, comprising: The image generation unit
A second skeletal model that generates a second skeletal model simulating the skeleton and joints of the patient based on the detection result of the second detection unit that detects the patient placed on the treatment table when performing the radiotherapy A generator,
Move each part of the human body model associated with the first skeleton model so that the positions of the skeleton and joint corresponding to the first skeleton model coincide with the positions of the skeleton and joint corresponding to the second skeleton model A human body model moving unit,
Based on the human body model moved by the human body model moving unit, compared with the X-ray image generated based on the CT image when positioning the patient when performing the radiation therapy on the patient A comparison X-ray image generation unit that generates a comparison X-ray image used to
The radiation therapy support system according to claim 2, comprising: The image generation unit generates a plurality of the images viewed from a plurality of directions.
The radiation therapy support system according to any one of claims 1 to 3. An image display unit that simultaneously displays the plurality of images generated by the image generation unit;
The radiation therapy support system according to claim 4. Correlate the position of the patient's skeleton and joints with the position of each part of the human body model that imitates the patient's body surface and interior,
Based on the result of the association, generate an image in which each part of the human body model is moved in accordance with the position of the skeleton and joints of the patient at the time of radiotherapy.
Image generation method. On the computer,
A process for associating the position of the patient's skeleton and joints with the position of each part of the human body model imitating the patient's body surface and interior;
Processing for storing the result of the association;
A process for generating an image in which each part of the human body model is moved in accordance with the position of the skeleton and joints of the patient at the time of radiotherapy based on the stored result of the correspondence;
An image generation program that executes