JP2021168824A - Positioning device, radiation therapy equipment, positioning method and computer program - Google Patents

Abstract

To perform accurate patient positioning without adding a photographing device.SOLUTION: A patient positioning device 70 for use in radiation therapy equipment A including a digital radiographic image photographing device 50 acquiring a digital radiographic image obtained by photographing a patient 9 using radioscopy and a bed control device 60 changing a position of a bed 7 on which the patient is mounted. The patient positioning device 70: acquires respective digital radiographic images at a plurality of positions of the bed 7 ; generates a composite digital radiographic image obtained by compositing the plurality of digital radiographic images by emphasizing a specific digital radiographic image in such a way that a specific portion whose relative position to the patient 9 is fixed exists at a specific position of the specific digital radiographic image; and uses the composite digital radiographic image to calculate an amount of movement of the bad 7 required for positioning of the bad 7 at the time of radiation therapy by the radiation therapy equipment A.SELECTED DRAWING: Figure 1

Description

The present invention relates to a positioning device, a radiotherapy device, a positioning method and a computer program.

Radiation therapy, which is one of the treatment methods for cancer, uses uncharged particle beams such as X-rays and gamma rays and charged particle beams such as proton beams and carbon beams as the radiation type used in the treatment. It is roughly divided into treatment. The latter treatment using a charged particle beam (charged particle beam) is generally called particle beam therapy.

The uncharged particle has the characteristic that the dose applied decreases at a constant rate from a shallow position to a deep position in the body, while the charged particle beam has a dose distribution (black curve) having a peak at a specific depth determined by energy. ) Is formed, so that the dose to normal tissues located deeper than the tumor can be significantly reduced by irradiating the beam with the peak position aligned with the tumor position.

In radiation therapy, irradiating the target tumor with a desired dose as accurately as possible leads to an improvement in the therapeutic effect. In order to realize accurate irradiation of the tumor with therapeutic radiation, it is necessary to align the patient with the same irradiation position as the treatment plan created by the treatment planning device at the time of actual irradiation. The alignment is called patient positioning.

Patient positioning in radiotherapy is generally performed using fluoroscopic X-ray images of the patient taken from two directions by two pairs of X-ray tubes arranged orthogonally and a plane detector. The captured fluoroscopic X-ray image and the CT image at the time of treatment planning are arranged in the virtual space, and the amount of attenuation of X-rays entering the virtual plane detector from the virtual X-ray tube is calculated from the same direction as the above-mentioned fluoroscopic X-ray image. This is carried out by comparing the projected image (hereinafter referred to as a pseudo-transparent X-ray image) created by the above and obtaining the amount of displacement required for the two to match. Here, the bone that serves as a mark on the fluoroscopic X-ray image (hereinafter referred to as the bone to be positioned) is manually aligned by a medical worker or automatically aligned by automatic calculation so as to coincide with the same site on the pseudo-transparent X-ray image. It is carried out by obtaining the displacement amount by.

However, the visibility of the bone to be positioned may be reduced due to the overlap of the structures (intestinal cavity, fixture, non-positioning bone) before and after the imaging direction, and in that case, the alignment by automatic calculation becomes difficult. , It corresponds with manual alignment that takes more time than automatic calculation. In radiotherapy, the patient positioning time occupies almost half of the total treatment time, and it is desirable that high-speed automatic alignment is performed for all patients in order to shorten the treatment time.

As a general technique in this technical field, there is a technique described in Patent Document 1.

Patent Document 1 states that "a step of scanning an object using a first imaging system (20) to obtain at least a first image (158) of the object and a first image (158). At the stage of determining the coordinates of the region of interest (ROI) (160) that can be observed in, the stage where the ROI (160) includes the abnormal portion (152) and the coordinates of the ROI (160) are used. Including the step of scanning the object by the second imaging system (14). "

Japanese Unexamined Patent Publication No. 2005-125080

Medical Physics (US), vol.44, No.11, p.5584-5595

Normally, in order to separate the overlap of the structures before and after the positioning target bone on the two-dimensional fluoroscopic X-ray image, it is conceivable to take measures to emphasize only the positioning target bone by image processing, but when viewed from the perspective imaging direction. It may be difficult to distinguish between the target bone and the structures existing before and after it, or in the case of a thick patient, the visibility of the target bone itself may be originally reduced due to a thick layer of soft tissue. In order to obtain information on only the target bone, it is usually conceivable to acquire 3D information, but in order to acquire 3D images, a new computed tomography (CT) or cone beam is installed in the treatment room of the existing facility. Introducing a computed tomography system (CBCT system) is considered to increase the burden on the facility management side both spatially and economically.

Further, as described in Patent Document 1, there is also a method called tomosynthesis imaging technique in which a fluoroscopic image is synthesized by emphasizing a tomographic image in which a target bone exists on a fluoroscopic image. Since it is necessary to acquire multiple fluoroscopic X-ray images with the emphasized part as the focal point and the imaging angle changed in order to create it, the X-ray tube and detector must operate during imaging, and the existing equipment needs to be modified. Become.

There is also an attempt to acquire tomosynthesis images using a plurality of X-ray tubes and a large plane detector. In the method described in Non-Patent Document 1, eight small X-ray tubes are arranged around the nozzle for irradiating the therapeutic radiation so that the focus is on the irradiation reference position of the therapeutic radiation called an isocenter, and the X-ray tubes are installed on the downstream side of the therapeutic radiation. Each X-ray is received in eight small areas of the large plane detector. It is a technique of acquiring eight X-ray images at the same time and adding and synthesizing the acquired eight X-ray images to acquire a composite image emphasizing an object having a depth near the isocenter. In this technique, a plurality of small X-ray tubes are required to acquire an image in which the shooting direction is changed.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a positioning device, a radiotherapy device, a positioning method, and a computer program capable of performing accurate patient positioning without adding an imaging device. ..

In order to solve the above problems, the positioning device according to one aspect of the present invention is a fluoroscopic X-ray imaging device that acquires a fluoroscopic X-ray image of a patient by X-ray fluoroscopy, and a position of a bed on which the patient is mounted. It is a positioning device used in a radiotherapy device having a sleeper control device to be changed, and a fluoroscopic X-ray image at each of a plurality of sleeper positions is acquired, and a specific location where the relative position with the patient is fixed is specific. A composite fluoroscopic X-ray image is generated by emphasizing this specific fluoroscopic X-ray image so as to be at a specific position of the fluoroscopic X-ray image and synthesizing a plurality of fluoroscopic X-ray images. It is characterized in that the amount of movement of the sleeper required for positioning the sleeper during radiotherapy by the radiotherapy device is calculated.

According to the present invention, accurate patient positioning can be performed without adding an imaging device.

It is a figure which shows the whole schematic structure of the radiotherapy apparatus which concerns on embodiment. It is a flowchart for demonstrating operation of the automatic patient positioning method by the positioning apparatus which concerns on embodiment of this invention. It is a conceptual diagram which shows the fluoroscopic X-ray image taking method necessary for creating a composite image in the positioning apparatus which concerns on embodiment. It is a conceptual diagram which shows the composite image creation method which considered the geometric arrangement of the apparatus in the positioning apparatus which concerns on embodiment. It is a flowchart for demonstrating operation of the composite image creation method by the positioning apparatus which concerns on Embodiment 1. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and are appropriately omitted and simplified for the sake of clarification of the description. The present invention can also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

In the figure for explaining the embodiment, the same reference numerals are given to the parts having the same function, and the repeated description thereof will be omitted.

The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range and the like disclosed in the drawings.

When there are a plurality of components having the same or similar functions, they may be described by adding different subscripts to the same reference numerals. However, when it is not necessary to distinguish between these plurality of components, the subscripts may be omitted for explanation.

In the present embodiment, as described below, a composite image created from a perspective X-ray image taken while moving the imaging target and a three-dimensional image at the time of treatment planning in the same system as the perspective X-ray image are used. A virtually created pseudo-perspective X-ray image is created, and a composite image in which the bone to be positioned is emphasized is created and used for positioning.

More specifically, in the present embodiment, two pairs of orthogonally arranged X-ray tubes and a plane detector, which have been conventionally used for patient positioning, are used to pass through an imaging region formed by both imaging devices. By moving the bed on which the patient is placed and taking continuous images, a fluoroscopic X-ray image in which the relative angle of the bone to be positioned with respect to the straight line between the X-ray tube and the center of the plane detector is changed is acquired. A composite fluoroscopic X-ray image that emphasizes the image of the depth of the positioning target bone is created by synthesizing the acquired plurality of X-ray images according to the depth of the positioning target bone in the patient's body. Similarly, a composite pseudo-transparent X-ray image is created using the same imaging system. By using the composite perspective X-ray image and the composite pseudo perspective X-ray image, the bone to be positioned can be emphasized, and an image in which the images of the structures existing before and after the imaging direction are blurred can be used for the patient positioning calculation. can.

The automatic patient positioning operation in the radiotherapy apparatus according to the present embodiment will be described with reference to FIGS. 1 to 5.

As shown in the overall configuration diagram of the radiotherapy device A in FIG. 1, the radiotherapy device A includes an accelerator 1, a beam transport device 2, a gantry 3, an irradiation nozzle 4, plane detectors 5A, 5B, and X. The wire tubes 6A and 6B, the sleeper 7, the robot arm 8, the treatment planning device 20, the communication device 30, the data server 40, the fluoroscopic X-ray imaging device 50, the sleeper control device 60, and the patient positioning device 70. Be prepared.

In order to irradiate the target with therapeutic radiation, the radiotherapy device A generates therapeutic radiation with the accelerator 1 and accelerates it to energy suitable for treatment. The beam transport device 2 then transports the accelerated therapeutic radiation to the gantry 3. The gantry 3 has a rotation mechanism and can irradiate the affected area of the patient with therapeutic radiation at various angles. The therapeutic radiation bent at an angle more suitable for the gantry 3 passes through the irradiation nozzle 4 and is applied to the affected area of the patient 9. The irradiation nozzle 4 incorporates a mechanism for changing the shape of therapeutic radiation so as to match the shape of the affected area of the patient. The patient 9 is placed on the bed 7 and moved to a pre-planned planned position by the robot arm 8 connected to the bed 7 before being irradiated with the therapeutic radiation. The planned position here refers to a position in the radiotherapy room that reproduces the same position and state as the treatment plan created in advance using the treatment planning device 12. The robot arm 8 can be driven in three translational directions and three rotational axial directions, and the bed 7 on which the patient 9 is placed can be arranged at an appropriate position and angle.

The treatment planning device 20 calculates and determines an appropriate irradiation angle, irradiation shape, and irradiation amount of the treatment radiation for the three-dimensional image of the patient 9 taken in advance as irradiation information. The determined irradiation information is stored in the data server 40 via the communication device 30.

The perspective X-ray image capturing apparatus 50 controls the plane detectors 5A and 5B and the X-ray tubes 6A and 6B arranged at right angles to acquire a perspective X-ray image. The acquired image is sent to the patient positioning device 70.

The patient positioning device 70 acquires irradiation information and three-dimensional image information of the patient from the data server 40 via the communication device 30, and creates a pseudo-transparent X-ray image by the pseudo-transparent X-ray image creating unit 71 of the patient positioning device 70. do. The composite image creation unit 72 creates a composite fluoroscopic X-ray image and a composite pseudo-transparent X-ray image from the fluoroscopic X-ray image and the pseudo-transparent X-ray image. The displacement amount calculation unit 73 calculates the displacement amount required for arranging the patient at the planned position using the composite fluoroscopic X-ray image and the synthetic pseudo-transparent X-ray image.

The patient positioning device 70 is composed of a device capable of various information processing, for example, an information processing device such as a computer. The information processing device has an arithmetic element, a storage medium, and a communication interface, and further has an input unit such as a mouse and a keyboard, and a display unit such as a display, if necessary.

The arithmetic element is, for example, a CPU (Central Processing Unit), an FPGA (Field-Programmable Gate Array), or the like. The storage medium includes, for example, a magnetic storage medium such as an HDD (Hard Disk Drive), a semiconductor storage medium such as a RAM (Random Access Memory), a ROM (Read Only Memory), and an SSD (Solid State Drive). Further, a combination of an optical disk such as a DVD (Digital Versatile Disk) and an optical disk drive is also used as a storage medium. In addition, a known storage medium such as a magnetic tape medium is also used as the storage medium.

Programs such as firmware are stored in the storage medium. At the start of operation of the patient positioning device 70 (for example, when the power is turned on), a program such as firmware is read from this storage medium and executed to perform overall control of the patient positioning device 70. In addition to the program, the storage medium stores data and the like required for each process of the patient positioning device 70.

The patient positioning device 70 of the present embodiment may be configured by a so-called cloud in which the information processing device is configured to be able to communicate via a communication network.

The patient positioning method of the present embodiment will be described with reference to FIG.

When positioning the patient for radiotherapy, the patient 9 is first placed on the bed 7 in the setup position, and an infrared laser installed in the treatment room is used so as to reproduce the patient position based on the irradiation information set by the treatment planning device 20. The body surface position is adjusted. After that, the bed 7 on which the patient 9 is placed moves toward the isocenter, which is the irradiation reference position of radiation, by controlling the robot arm 8 via the bed control device 60 (Step 100).

The bed 7 is from the bed position 200 outside the irradiation regions 12A and 12B in FIG. 3 in which the patient's positioning target bone 10 (see FIG. 3) is formed by the plane detectors 5A and 5B and the X-ray tubes 6A and 6B. , It moves so as to straddle the irradiation areas 12A and 12B. By controlling the fluoroscopic X-ray imaging apparatus 50 while the positioning target bone 10 moves in the irradiation regions 12A and 12B, a plurality of fluoroscopic X-ray images (Digital Radiography: DR) are acquired (Step 101).

After that, the acquired plurality of DRs are transferred to the composite image creation unit 72 of the patient positioning device 70, and the composite image creation unit 72 creates a composite DR by DR synthesis so as to emphasize the layer of the isocenter depth (Step 102). ..

A composite image creation method using the shift addition method will be described with reference to FIGS. 3 and 4 as an example of the composite image creation method shown in Step 102 in the patient positioning device 70 of this embodiment.

Here, for convenience, among the perspective X-ray images acquired at the three sleeper positions 201, 202, and 203 in FIG. 3, the perspective X-ray images 1A, 2A, and 3A (204,) acquired by the plane detector 5A and the X-ray tube 6A. Only 205, 206) will be described.

The positioning target bones 10 photographed at the bed positions 201, 202, and 203 are detected by the detection elements located at the intersections of the dotted line in the figure and the plane detector 5A, and are reflected on the fluoroscopic X-ray image. Using the position log information of the sleeper at the time of X-ray photography, the fluoroscopic X-ray image 1A and the fluoroscopic X-ray image 3A are left and right based on the fluoroscopic X-ray image 2A acquired when the positioning target bone 10 is at the isocenter 80 position. Shift to to create an additional image.

Since the moving direction of the sleeper 7 of the present embodiment is at an angle of 45 degrees with the shooting direction and the positioning target bone 10 to be emphasized exists at the isocenter height, the shift amount of the image is the actual movement amount of the sleeper. It corresponds to the value obtained by multiplying by sinθ and multiplying by the image enlargement ratio. Here, θ is the angle formed by the center of the X-ray tube 6A-plane detector 5A and the horizontal plane (see FIG. 4), and the image magnification is defined as the distance from the X-ray tube 6A to the position of the isocenter 80 as a. It is a value represented by (a + b) / a, where b is the distance from the position of the isocenter 80 to the plane detector 5A.

今回、図示する撮影体系ではθ＝４５°であるため、ｘ_１、ｘ_２は下記のように表される。

_{Therefore, the rightward shift amount x 1 of} the perspective X-ray image 1A (204) _{and the leftward shift amount x 2} of the perspective X-ray image 3A (206) are expressed as follows.

Since θ = 45 ° in the imaging system shown this time, x ₁ and x ₂ are expressed as follows.

The procedure of the composite image creation method shown in Step 102 of FIG. 2 will be described with reference to the flow of FIG.

First, all the captured DRs are read (Step150). The position information of the bed 7 at the time of each DR shooting is acquired from the log information of the bed control device 60 (Step 151). Set the reference position (e.g. isocenter) on the same layer as the layer to be emphasized (Step 152). The distance d from the position of the bed 7 to the reference position at the time of each DR shooting is calculated (Step 153). Using the information of the distance a between the X-ray tube and the reference position, the distance b between the center of the plane detector and the reference position, and the distance d, the shift amount x required for the image shift is calculated for each DR (Step 154). .. A composite image 207 is created by shifting and adding each DR according to the shift amount (Step 155). The composite image creation process is completed through the above procedure (Step 156).

After creating a composite image in Step 102 of the flow shown in FIG. 2 by the above processing method, a pseudo-transparent X-ray is created by virtually projecting from three-dimensional information which is positioning reference information at the time of treatment planning in patient positioning. In order to prepare an image (Digitally Reconstructed Radiography: DRR), the initial values of translation 3 degrees of freedom and rotation 3 degrees of freedom required for DRR creation are set (Step 103).

A plurality of DRRs are created from CT under the same imaging conditions as each DR acquisition condition in Step 101 (Steo 104). A synthetic DRR is created from a plurality of DRRs by the same synthesis method as Step 102 (Step 105).

The degree of coincidence between the synthetic DR and the synthetic DRR produced by Step 102 and Step 105 is calculated (Step 106). As the similarity index, a commonly used normalized mutual correlation coefficient, mutual information amount, or the like may be used, or other similarity indexes may be used.

Next, it is determined whether the calculated similarity satisfies the preset convergence condition (Step 107). If the convergence condition is not satisfied, the condition that satisfies the convergence condition (translation 3 degrees of freedom, rotation 3 degrees of freedom, total 6 degrees of freedom) is obtained by optimization processing. There are methods such as the downhill simplex method and the Powell method for the optimization process of multiple variables such as 6 degrees of freedom, but other methods may be used.

In the optimization process, the value of 6 degrees of freedom is updated (Step 108), and Steps 104 to 108 are repeated. When the degree of agreement satisfies the convergence condition in Step 107, the patient can be moved from the current position to the position at the time of treatment planning by moving the bed based on the obtained value of 6 degrees of freedom, and precise positioning is possible. It can be carried out (Steo109). With the above, the automatic patient positioning is completed (Step 110), and the actual irradiation of the therapeutic radiation is performed.

Therefore, according to this embodiment, it is possible to realize a positioning device, a radiotherapy device, a positioning method, and a computer program capable of performing accurate patient positioning without adding an imaging device.

More specifically, by using the above-mentioned composite images for patient positioning, the positioning target bone can be used even for a patient with overlapping non-target bones or a large body thickness, even though the addition of an imaging device is not required. You will be able to perform automatic calculation positioning based on. In addition, since this imaging operation can be incorporated into the bed operation, which is incorporated as a general patient positioning workflow, it is considered that the influence of the application of this technology on the increase in positioning time is small.

Further, according to the present embodiment, since the composite images in which the positioning target bones 10 are emphasized are used, the positions by automatic calculation are conventionally calculated even when the positioning target bones have low visibility and manual alignment is required. Alignment is possible, which leads to shortening of positioning time. Further, since the composite image is an image created by integrating the images in principle, it is not necessary that each fluoroscopic X-ray image is an image having a sufficient signal-to-noise ratio (SN). Therefore, the total X-ray dose for imaging may be small, and imaging at a low dose becomes possible.

The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace other configurations with respect to a part of the configurations of each embodiment.

As an example, the accelerator 1 described in the present embodiment may be an electron beam accelerator assuming therapeutic X-rays, or a particle beam accelerator such as a proton or carbon.

Further, the image shift amount required for creating the composite image may be calculated based on the position log information of the bed, or may be obtained by installing a marker on or in the bed. When calculating the sleeper position using markers, the trigonometry is performed from the two-dimensional position information of the markers on the image acquired by the two pairs of X-ray plane detectors and the geometric arrangement of the X-ray tube and the plane detector. It is used to calculate and use the three-dimensional position information of the marker.

Further, regarding the moving direction of the sleeper at the time of taking a fluoroscopic X-ray image, the moving direction may be changed according to the positional relationship between the positioning target bone and the non-positioning target bone. For example, as in the present embodiment, the image may be taken by moving left and right in the horizontal direction, or by moving in the cranio-caudal direction or the ventral-dorsal direction (vertical direction). By creating a composite image by an imaging method in which the non-positioning target bone is moved in the direction perpendicular to the straight line at the end to be removed, the effect of blurring the image of the non-positioning target bone can be obtained.

Further, as a method of creating a composite image, the shift addition method of shifting and adding images to each other has been described in this embodiment, but an analytical reconstruction method such as a filterback project method generally used for compositing tomosynthesis images can be used. It is also possible to reconstruct the image using a statistical reconstruction method such as the successive approximation reconstruction method.

Regarding the composite image used for patient positioning, in the present embodiment, two composite images are created from the perspective X-ray images acquired by each of the two pairs of X-ray-plane detectors, and simulated by the same imaging system. Although it was shown that positioning was performed using two composite pseudo-perspective X-ray images synthesized by the above, one composite image was created using all the images acquired by the two pairs of X-ray-plane detectors. However, positioning may be performed using the composite pseudo-transparent X-ray image created in the same manner. Further, the X-ray tube and the plane detector to be used do not necessarily have to be two pairs, and a composite image may be created from an image acquired by using one pair or three or more pairs and used for patient positioning.

Further, each of the above configurations, functions, processing units, processing means and the like may be realized by hardware by designing a part or all of them by, for example, an integrated circuit. Further, each of the above configurations, functions, and the like may be realized by software by the processor interpreting and executing a program that realizes each function. Information such as programs, tables, and files that realize each function can be placed in a memory, a recording device such as a hard disk or SSD, or a recording medium such as an IC card, SD card, or DVD.

In addition, the control lines and information lines indicate those that are considered necessary for explanation, and do not necessarily indicate all the control lines and information lines in the product. In practice, it can be considered that almost all configurations are interconnected.

A ... Radiation therapy device 1 ... Accelerator 2 ... Beam transport device 3 ... Gantry 4 ... Irradiation nozzle 5A, 5B ... Flatness detector 6A, 6B ... X-ray tube 7 ... Sleeper 8 ... Robot arm 9 ... Patient 10 ... Positioning target bone 11 ... Positioning non-target bone 20 ... Treatment planning device 30 ... Communication device 40 ... Data server 50 ... Fluoroscopic X-ray imaging device 60 ... Sleeper control device 70 ... Patient positioning device 71 ... Pseudo-transparent X-ray image creation unit 72 ... Synthetic image creation Part 73 ... Displacement amount calculation part 80 ... Isocenter

Claims (11)

A positioning device used in a radiotherapy device having a fluoroscopic X-ray imaging device that acquires a fluoroscopic X-ray image of a patient by X-ray fluoroscopy and a bed control device that changes the position of the bed on which the patient is mounted. There,
Each of the fluoroscopic X-ray images at the positions of the plurality of sleepers is acquired, and the specific location where the relative position with the patient is fixed is at a specific position of the specific fluoroscopic X-ray image. A composite fluoroscopic X-ray image is generated by emphasizing the fluoroscopic X-ray image and synthesizing the plurality of the fluoroscopic X-ray images, and the composite fluoroscopic X-ray image is used to generate a composite fluoroscopic X-ray image of the bed during radiotherapy by the radiotherapy apparatus. A positioning device characterized by calculating the amount of movement of the sleeper required for positioning. The positioning device according to claim 1, wherein the specific location is a specific region of the patient. The first aspect of claim 1, wherein a composite perspective X-ray image is generated by synthesizing the plurality of the perspective X-ray images so that the specific portion is located at substantially the same position of the plurality of the perspective X-ray images. Positioning device. A composite fluoroscopic X-ray image obtained by synthesizing the plurality of fluoroscopic X-ray images by moving the composite position of the fluoroscopic X-ray images so that the specific location is substantially the same position of the plurality of fluoroscopic X-ray images. The positioning device according to claim 2, wherein the positioning device is generated. The first aspect of claim 1, wherein the plurality of fluoroscopic X-ray images are taken when the bed is moved from the position where the patient is mounted to the position of the radiotherapy by the radiotherapy apparatus. Positioning device. A plurality of pseudo-perspective images obtained by acquiring a three-dimensional tomographic image of the patient, and based on the three-dimensional tomographic image, the patient is photographed at the positions of the plurality of sleepers in the same arrangement as that taken by the fluoroscopic X-ray imaging apparatus. An X-ray image is generated, and the specific pseudo-transparent X-ray image is emphasized so that the specific location is at the specific position of the specific pseudo-transparent X-ray image, and the plurality of the fluoroscopic X-ray images are combined. The combined pseudo-transparent X-ray image is generated, and the synthetic pseudo-transparent X-ray image and the synthetic pseudo-transparent X-ray image are used to move the sleeper required for positioning the sleeper during radiation treatment by the radiation therapy apparatus. The positioning device according to claim 1, wherein the image is calculated. The claim is characterized in that the composite pseudo-perspective X-ray image is generated by synthesizing the plurality of pseudo-perspective X-ray images so that the specific portion is located at substantially the same position of the plurality of pseudo-perspective X-ray images. 6. The positioning device according to 6. The positioning device according to claim 1, wherein the specific location is a marker whose relative position with respect to the patient is fixed. A fluoroscopic X-ray imaging device that acquires a fluoroscopic X-ray image of a patient by X-ray fluoroscopy, a sleeper control device that changes the position of the sleeper on which the patient is mounted, and a positioning device that positions the sleeper. It is a positioning device used for the radiotherapy device that it has.
The positioning device is
Each of the fluoroscopic X-ray images at the positions of the plurality of sleepers is acquired, and the specific location where the relative position with the patient is fixed is at a specific position of the specific fluoroscopic X-ray image. A composite fluoroscopic X-ray image is generated by emphasizing the fluoroscopic X-ray image and synthesizing the plurality of the fluoroscopic X-ray images, and the synthetic fluoroscopic X-ray image is used to generate a composite fluoroscopic X-ray image of the bed during radiotherapy by the radiotherapy apparatus. A radiotherapy apparatus characterized by calculating the amount of movement of the sleeper required for positioning. By a positioning device used in a radiotherapy device having a fluoroscopic X-ray imaging device that acquires a fluoroscopic X-ray image of a patient by X-ray fluoroscopy and a bed control device that changes the position of the bed on which the patient is mounted. It ’s a positioning method,
The fluoroscopic X-ray images at the positions of the plurality of beds are acquired, respectively.
The plurality of the perspective X-ray images are combined by emphasizing the specific perspective X-ray image so that the specific location where the relative position with the patient is fixed is at a specific position of the specific perspective X-ray image. Generate a composite perspective X-ray image
A positioning method characterized by calculating the amount of movement of the berth required for positioning the berth during radiotherapy by the radiotherapy apparatus using this synthetic fluoroscopic X-ray image. Executed by a computer used in a radiotherapy device having a fluoroscopic X-ray imaging device that acquires a fluoroscopic X-ray image of a patient taken by X-ray fluoroscopy and a bed control device that changes the position of the bed on which the patient is mounted. It is a computer program that is used
A function to acquire the fluoroscopic X-ray images at the positions of the plurality of beds, and
The plurality of the perspective X-ray images are combined by emphasizing the specific perspective X-ray image so that the specific location where the relative position with the patient is fixed is at a specific position of the specific perspective X-ray image. A function to generate a composite perspective X-ray image
A computer program that realizes a function of calculating the amount of movement of the sleeper required for positioning the sleeper during radiotherapy by the radiation therapy apparatus using this synthetic fluoroscopic X-ray image.

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