JP7082366B2 - Radiation therapy device, bed positioning device, and bed positioning method - Google Patents

Description

The present invention relates to a treatment device using radiation and a method for positioning a patient bed, and in particular, a radiation therapy device that irradiates an affected area with particle beams such as proton beams and carbon beams or X-rays, and a suitable bed positioning device and bed. Regarding the positioning method of.

For the purpose of providing a treatment device using an ion beam that can shorten the time required for positioning the bed, in Patent Document 1, the treatment device using an ion beam is provided with an ion beam irradiation device provided with an X-ray tube. An X-ray detector with a rotating gantry and multiple X-ray detectors is movably installed in the direction of the rotation axis of the rotating gantry, and the bed on which the patient rests is on the extension of the ion beam path of the irradiator. The X-ray tube is moved until the affected area is almost located, the X-ray tube is located in the ion beam path, the X-ray detector is located on its extension line, and the X-ray tube emits X-rays as the rotating gantry rotates. And an X-ray detector swirls around the patient, the X-rays radiate to the patient, pass through the patient, are detected by the X-ray detector, and are based on the signal output from the X-ray detector. It is described that tomographic image information is created and bed positioning information is created using this tomographic image information.

Patent No. 4130680

A treatment method is known in which an irradiation target center is set on an affected part of a patient such as cancer and irradiation with particle beams such as proton beams and carbon beams or X-rays. Among these treatments, the particle beam therapy device used for particle beam therapy includes a beam generator consisting of an accelerator and a beam transport system, an irradiation field forming device, and a positioning device consisting of an X-ray fluoroscope and a patient bed. The particle beam accelerated by the accelerator reaches the irradiation field forming device via the beam transport system, is monitored by this irradiation field forming device, and is shaped to fit the shape of the affected part of the patient.

Particle beams such as proton beams and carbon beams have the property of releasing most of the energy immediately before they stop, and the resulting dose distribution is called the Bragg peak. The particle beam therapy device utilizes this property to select the energy of the particle beam to stop the particle beam at the irradiation target and release most of the energy to the affected area.

In such particle beam therapy, a CT image (reference CT image) of a patient is previously imaged with an X-ray CT device in order to determine the irradiation position and irradiation amount of the particle beam. The position of the affected area is confirmed on this reference CT image, and the arrangement of the patient at the time of particle beam irradiation is determined.

Before irradiating the particle beam, the affected area must be properly placed with respect to the irradiation field forming device so that the dose is maximum in the affected area and does not damage normal tissue. Therefore, the patient bed is positioned by the positioning device. In order to reliably position the patient with respect to the irradiation field forming device using the positioning device, collation is mainly performed by an X-ray fluoroscopic image.

X-ray generators and X-ray receivers are located on both sides of the patient lying on the bed, and the X-ray receiver produces an X-ray fluoroscopic image of the patient prior to irradiation of the particle beam. The movement direction and the movement distance of the patient bed with respect to the irradiation field forming apparatus so that the generated X-ray fluoroscopic image and the reference image calculated from the reference CT image captured in advance match are obtained. After that, the positioning control of the patient bed is performed based on the obtained positioning direction and the moving distance, and the patient is positioned.

In the above-mentioned Patent Document 1, a CT image (CT at the time of irradiation) obtained by acquiring an X-ray fluoroscopic image at a plurality of angles using an X-ray fluoroscopic device that rotates around the patient together with an irradiation field forming device and reconstructing the acquired image. The moving direction and amount of movement of the bed are calculated so that the image) and the reference CT image match, and the patient is positioned.

Here, in order to reconstruct the CT image at the time of irradiation, an X-ray fluoroscopic image from a direction of at least 180 degrees around the patient is required, and in Patent Document 1, an irradiation field forming apparatus and an X-ray fluoroscopic apparatus are used. By rotating around the patient together, X-ray fluoroscopic images from multiple angles are acquired.

Further, in the treatment device, in addition to the device having a mechanism for rotating the irradiation field forming device around the patient as described in Patent Document 1, the irradiation field forming device is fixed and one or two. There is also a device that irradiates particle beams from only one or two directions with a table irradiation field forming device. In such a device, a CT image can be acquired by rotating a structure in which an X-ray generator and an X-ray receiver are arranged at both ends of the C-shape around the patient.

However, when a fluoroscopic device for acquiring a fluoroscopic image or a structure for moving the fluoroscopic device is provided, there is a risk of interference between the fluoroscopic device or the structure and another device such as an irradiation field forming device, and it is difficult to arrange the device. There are cases. In addition, since it is necessary to evacuate during treatment, it is necessary to secure a place to evacuate, which causes a space problem.

An object of the present invention is a radiation therapy device, a bed positioning device, and a bed positioning method that can solve the problem of interference between a fluoroscope and another structure such as an irradiation field forming device and the problem of space as compared with the conventional case. Is to provide.

The present invention includes a plurality of means for solving the above problems, for example, a bed configured to allow at least one of tilting from a horizontal direction and rotation in a horizontal plane. A radiation fluoroscope that acquires a perspective image of an imaged object on the bed, and a plurality of radiation fluoroscopes whose positions are fixed during acquisition of the perspective image, and a fluoroscope acquired by the radiation fluoroscope. A positioning control device having a function of moving the position of the bed based on an image is provided, and the positioning control device acquires a perspective image at a plurality of bed tilt angles and is based on the obtained plurality of perspective images. In addition to executing the control to move the position of the bed, if there is an angle that matches the angle of irradiating the radiation among the plurality of bed tilt angles, the fluoroscopic image is acquired at the angle that matches the angle of irradiating the radiation. It is characterized in that the inclination angle of the bed is controlled so as to be performed last .

According to the present invention, it is possible to solve the problem of interference between the fluoroscopic device and other structures such as the irradiation field forming device and the problem of space as compared with the conventional case.

It is a figure which shows the whole structure of the particle beam therapy apparatus in the Example of this invention. It is a figure which shows the schematic structure of the device arranged in the treatment room in the particle beam therapy apparatus of this Example. It is a figure which shows an example of the input screen of the inclination angle of a bed displayed on the console in the particle beam therapy apparatus of this Example. It is a flow chart which carries out the particle beam irradiation by the particle beam therapy apparatus of this Example. It is a flow diagram which carries out the bed positioning in the particle beam therapy apparatus of this Example. It is a figure which shows the outline of the apparatus arranged in the treatment room of the particle beam therapy apparatus which performs positioning by using the fluoroscopic image by particle beam which is another Example of this invention. It is a figure which shows the schematic structure of the X-ray therapy apparatus which is another Example of this invention.

Examples of the radiation therapy device, the bed positioning device, and the bed positioning method of the present invention will be described with reference to FIGS. 1 to 7. In this embodiment, a particle beam therapy device will be described as an example of a radiation therapy device, but as will be described later, the same effect can be obtained by applying the present invention to an X-ray therapy device.

First, an outline of the particle beam therapy device and the bed positioning device will be described with reference to FIG. FIG. 1 is a diagram showing an overall configuration of a particle beam therapy device.

In FIG. 1, the particle beam therapy device includes a charged particle beam generator 11, a high energy beam transport system 20, irradiation field forming devices 31A and 31B, a bed positioning device, a central control device 312, a memory 313, an irradiation control device 314, and a console. (Display device) 315 is provided.

Of these, the bed positioning device includes a bed 33, a bed drive device 34, an X-ray generator 35A, 35B, 35C, 35D, an X-ray receiver 36A, 36B, 36C, 36D, and a positioning control device 311. Further, the particle beam therapy device is connected to the treatment planning device 501 via the central control device 312.

The charged particle beam generator 11 is composed of an ion source 12, a pre-stage accelerator 13, and a particle beam accelerator 14. In this embodiment, a synchrotron type particle beam accelerator is assumed as the particle beam accelerator 14, but another known particle beam accelerator such as a cyclotron can be used as the particle beam accelerator 14. As shown in FIG. 1, the synchrotron type particle beam accelerator 14 has a deflection electromagnet 15, an accelerator 16, a high frequency application device 17 for emission, a deflector 18 for emission, and a quadrupole electromagnet (not shown) on its orbit. ).

FIG. 1 will explain the process from the particle beam generation from the charged particle beam generator 11 using the synchrotron type particle beam accelerator 14 to the emission toward the patient 40.

First, the particles supplied from the ion source 12 are accelerated by the pre-stage accelerator 13 and sent to the synchrotron which is a beam accelerator. An accelerating device 16 is installed in the synchrotron, and a high frequency is applied to a high frequency accelerating cavity (not shown) provided in the accelerating device 16 in synchronization with the period in which the particle beam orbiting in the synchrotron passes through the accelerating device 16. Is applied to accelerate the particle beam. In this way, the particle beam is accelerated until it reaches a predetermined energy.

After the particle beam is accelerated to a predetermined energy (for example, 70 to 250 MeV in the case of a proton beam), when an emission start signal is output from the central control device 312 via the irradiation control device 314, the high frequency application device 17 is output. High-frequency power from the high-frequency power supply 19 is applied to the particle beam orbiting in the synchrotron by the installed high-frequency application electrode, and the particle beam is emitted from the synchrotron.

The high energy beam transport system 20 communicates the synchrotron with the irradiation field forming devices 31A and 31B. The particle beam taken out from the synchrotron is guided to the irradiation field forming devices 31A and 31B installed in the treatment room 30 via the high energy beam transport system 20. One or more irradiation field forming devices may be provided. In this embodiment, two are provided. When two or more are provided as in this embodiment, the particle beam is generated by changing the excitation amount of the deflection electromagnet 21 arranged at the branch position of the high energy beam transport system 20. The irradiation field forming devices 31A and 31B to be transported can be selected.

The irradiation field forming devices 31A and 31B are devices that shape the shape of the particle beam to be finally irradiated to the patient 40, and the structure thereof differs depending on the irradiation method. The scatterer method and the scanning method are typical irradiation methods, and the present invention is effective in either of the irradiation methods. In this embodiment, a case where the scanning method is used will be described. In the scanning method, a high-dose region is finally formed only on the target by three-dimensionally scanning a thin particle beam transported from the high-energy beam transport system 20.

The irradiation field forming devices 31A and 31B each include two scanning electromagnets, a dose monitor, and a beam position monitor. The dose monitor measures the amount of particle beams that have passed through the monitor. On the other hand, the beam position monitor measures the position where the particle beam has passed. Based on the information from these monitors, the irradiation control device 314 manages that the planned position is irradiated with the planned amount of particle beams.

The traveling direction of the fine particle beam transported from the charged particle beam generator 11 via the high energy beam transport system 20 is deflected by the scanning electromagnet. These scanning electromagnets are provided so that magnetic lines of force are generated in a direction perpendicular to the beam traveling direction, and by using two electromagnets, particle beams can be moved to any position in a plane perpendicular to the beam traveling direction. It is possible to irradiate the target with a particle beam. The irradiation control device 314 controls the amount of current flowing through the scanning electromagnet. The amount of deflection of the particle beam can be freely set by exciting a magnetic field corresponding to the amount of current.

There are two scanning methods for the beam. One is a discrete method in which the irradiation position is repeatedly moved and stopped, and the other is a method in which the irradiation position is continuously changed.

In the discrete method, first, a specified amount of particle beam is irradiated while keeping the irradiation position at a certain point. This point is called a spot. After the spot is irradiated with the specified amount of particle beam, the irradiation of the particle beam is temporarily stopped, and then the exciting current amount of the scanning electromagnet is changed so that the spot can be irradiated to the next position. The amount of exciting current is changed, and after moving to the next irradiation position, the particle beam is irradiated again.

The method of continuously moving the irradiation position changes the irradiation position while irradiating the particle beam. That is, while continuously changing the excitation amount of the scanning electromagnet, it is moved while irradiating the beam so as to pass through the entire irradiation field. The change in the irradiation amount for each irradiation position in this method is realized by modulating the scanning speed, the intensity of the particle beam (current value), or both.

The particle beam stops at a certain position in the direction of travel and imparts most of the energy to that stop position. The energy of the particle beam is adjusted so that the stopping depth of the beam is within or near the target. For example, in the case of the discrete method, the spots registered to be irradiated with the adjusted energy are sequentially irradiated. The amount of particle beams to be irradiated for each spot is predetermined, and a predetermined amount of particle beams is irradiated for each spot. Once all spots have been irradiated, the depth at which the beam is stopped is changed to illuminate other depth locations within the target.

In order to change the stopping depth of the beam, the energy of the beam applied to the patient 40 is changed. One of the methods of changing the energy is to change the setting of the particle beam accelerator, that is, the synchrotron in this embodiment. The particle beam is accelerated to the set energy in the synchrotron, and the energy incident on the patient 40 can be changed by changing this set value. In this case, since the energy taken out from the synchrotron changes, the energy when passing through the high energy beam transport system 20 also changes, and it is necessary to change the setting of the high energy beam transport system 20.

In this way, when the information of the energy, the irradiation position, and the irradiation amount for each spot is input, the particle beam therapy device irradiates the particle beam toward the target and forms a dose distribution. Information such as energy, irradiation position, and irradiation amount for each spot is determined by the treatment planning device 501.

Prior to treatment, a CT image (hereinafter referred to as a reference CT image) is imaged by an X-ray CT device. The treatment planning device 501 calculates the dose distribution formed by the particle beam in the patient's body using the reference CT image, and forms the dose distribution so that the target is covered. The installation position of the patient 40, the angle of the bed 33, and the irradiation. The field forming devices 31A and 31B, the energy for each spot, the irradiation position, and the irradiation amount are determined. The treatment room 30 has a reference position fixed to the treatment room 30 on a particle beam passage path called an isocenter. By designating the position in the body that should match this reference position, the installation position of the patient 40 is specified. Further, although it is uniquely determined when one irradiation field forming device is used, this embodiment is provided with two irradiation field forming devices 31A and 31B so that particle beams are irradiated from two directions, an upward direction and a horizontal direction. In the case of the treatment room 30 as described above, the irradiation field forming devices 31A and 31B for irradiating the particle beam are selected.

The treatment planning device 501 transmits these determined information to the central control device 312. The central control device 312 records the received information in the memory 313.

The details of the configuration of the treatment room 30 will be described with reference to FIG. FIG. 2 shows a case where the patient 40 is viewed from the foot side.

As shown in FIG. 2, the treatment room 30 of this embodiment includes two irradiation field forming devices 31A and 31B, a bed 33, a bed driving device 34, and four X-ray fluoroscopes.

Of these, the radiation fluoroscope is a pair of X-ray generator 35A and X-ray receiver 36A, a pair of X-ray generator 35B and X-ray receiver 36B, and an X-ray generator 35C and X-ray receiver 36C. It is a fluoroscope that acquires a fluoroscopic image by X-rays, consisting of a pair of an X-ray generator 35D and a pair of an X-ray receiver 36D, a total of four pairs of an X-ray generator and an X-ray receiver.

The bed 33 is composed of a top plate for allowing the patient 40 whose target is the object to be imaged and the object to be irradiated with the particle beam to stand still. The bed 33 can be tilted from the horizontal direction by rotating around the x-axis and the y-axis, and can rotate in the horizontal plane by rotating around the z-axis.

The bed drive device 34 moves the patient 40 rested on the bed 33 in each of the three orthogonal xyz directions and rotates around the x-axis, y-axis, and z-axis. It is a device that can be moved, for example, an articulated robot arm. The bed driving device 34 is connected to the bed 33, and the bed 33 can be moved to a position and an angle specified by the positioning control device 311.

The irradiation field forming device 31A can irradiate the patient 40 on the bed 33 with a particle beam from a vertical direction, and the irradiation field forming device 31B irradiates the patient 40 on the bed 33 with a particle beam from a horizontal direction. It is placed in a position where it can be.

An X-ray fluoroscope (a pair of an X-ray generator 35A and an X-ray receiver 36A) that images vertically to the patient 40 on the bed 33 and an X-ray fluoroscope (X-ray generator 35B) that images horizontally. Of the pairs of X-ray receivers 36B), the positions of the X-ray receivers 36A and 36B overlap with the irradiation path of the particle beam. For this reason, the position is fixed during acquisition of the fluoroscopic image, but it is provided with a drive mechanism (not shown) configured and controlled so as to be able to evacuate from the path of the particle beam when irradiating the particle beam. The X-ray generators 35A and 35B are fixed to the wall, floor, or the like of the treatment room 30. The two X-ray fluoroscopes can capture fluoroscopic images from the front and sides of the patient. Such fluoroscopic images from the front and sides are familiar to operators such as doctors who operate particle beam therapy devices.

The other two X-ray fluoroscopes (X-ray generator 35C and X-ray receiver 36C pair and X-ray generator 35D and X-ray receiver 36D pair) are at an angle of 45 degrees with respect to the patient 40. Placed in. These two X-ray fluoroscopes are not arranged on the irradiation path of the particle beam irradiated by the irradiation field forming devices 31A and 31B. Therefore, it is possible to acquire an X-ray fluoroscopic image even while irradiating a particle beam. Therefore, these two pairs of X-ray fluoroscopes are suitable for so-called moving object tracking, in which the position of a target is measured even when the target moves by acquiring an X-ray fluoroscopic image during irradiation with a particle beam. X-ray fluoroscope. By performing moving object tracking using such an X-ray fluoroscope, the particle beam can be irradiated only when the measured target position comes to the planned position, so that the particle beam can be targeted with higher accuracy. Can be focused and irradiated. Since the X-ray generators 35C and 35D and the X-ray receivers 36C and 36D do not need to be retracted, they are fixed to the wall or floor of the treatment room 30.

In this embodiment, it is assumed that two X-ray fluoroscopes of two types having different main roles are provided, for a total of four X-ray fluoroscopes, but the number of X-ray fluoroscopes is multiple. Any number of units may be used, and at least two units may be used.

The arrangement method of the X-ray fluoroscope is not limited to the pattern shown in FIG. 2, and the positions of the X-ray generators 35A, 35B, 35C, 35D and the X-ray receivers 36A, 36B, 36C, 36D are interchanged. You may. In that case, the X-ray generators 35A and 35B on the particle beam irradiation path are configured to move to the retracted position.

Returning to FIG. 1, the positioning control device 311 has a function of moving the position of the bed 33 based on the X-ray fluoroscopic image acquired by the X-ray fluoroscopic device. The positioning control device 311 sets the position of the target in the patient 40 on the bed 33 as an isocenter based on the X-ray fluoroscopic images acquired by the four X-ray fluoroscopes in a state where a plurality of tilt angles of the bed 33 are changed. The movement amount of the bed 33 for matching is calculated, and the movement command is output to the bed drive device 34.

For example, the positioning control device 311 reconstructs a CT image (tomographic image) at the time of irradiation from the acquired X-ray fluoroscopic image, and compares the CT image at the time of irradiation with a reference CT image acquired in advance to obtain a target. The amount of movement of the bed 33 for matching the position with the isocenter is calculated.

A general method can be used for this reconstruction, but in that case, it is desirable to consider individual differences of a plurality of X-ray fluoroscopes. Usually, the X-ray fluoroscope includes individual differences depending on the installation position, method, specifications, and the like. Therefore, when reconstructing the CT image at the time of irradiation from the acquired X-ray fluoroscopic image, it is desirable to reconstruct it after considering the individual difference of each X-ray fluoroscopic device that acquired the X-ray fluoroscopic image.

Further, the positioning control device 311 acquires information on the irradiation of the particle beam from the treatment planning device 501, and when it is determined that there is an angle matching the angle of irradiating the particle beam among the plurality of bed inclination angles, the positioning control device 311 acquires the information regarding the irradiation of the particle beam. The tilt angle of the bed 33 and the schedule for acquiring the X-ray fluoroscopic image are controlled so that the acquisition of the X-ray fluoroscopic image at an angle matching the angle of irradiating the particle beam is finally performed.

Further, the positioning control device 311 displays a plurality of bed tilt angle input screens for acquiring an X-ray fluoroscopic image on the console 315, and tilts the bed 33 based on the bed tilt angle input by the console 315. FIG. 3 shows an example of a screen for inputting the inclination angle of the bed 33.

In FIG. 3, the bed tilt angle input screen 710 displayed on the console 315 has individual bed tilt angle input fields 712, O.D. The K button 714 and the cancel button 716 are displayed. The operator operates the console 315 to input the bed tilt angle for acquiring the X-ray fluoroscopic image in the individual bed tilt angle input fields 712, and when the input of all the angles is completed, the O.D. Press the K button 714. O. When the K button 714 is pressed, acquisition of an X-ray fluoroscopic image by a plurality of X-ray fluoroscopic devices at the bed tilt angle input in the bed tilt angle input field 712 is executed. To end the bed tilt angle input or cancel the input, press the cancel button 716.

Next, the entire flow of particle beam irradiation including the bed positioning method of the present invention will be described with reference to FIGS. 4 and 5. First, the overall flow of particle beam irradiation will be described with reference to the flow chart of FIG.

As shown in FIG. 4, the patient 40 first enters the treatment room 30 (step S101).

Next, the patient 40 lies on the bed 33 and performs the positioning of the bed 33, which is a feature of the present invention (step S102). In this step, the central control device 312 reads the information determined by the treatment planning device 501 recorded in the memory 313. Information necessary for positioning is transmitted from the central control device 312 to the positioning control device 311. The detailed flow of positioning will be described later with reference to FIG.

Next, the irradiation field forming devices 31A and 31B for irradiating the particle beam are selected (step S103). Further, information such as energy and irradiation amount for each spot required for irradiation is transmitted from the central control device 312 to the irradiation control device 314. When the process returns from step S105, in this step, the irradiation field forming devices 31A and 31B for irradiating the particle beam are changed.

Next, the central control device 312 controls the particle beam generator, the high energy beam transport system 20, and the irradiation field forming devices 31A and 31B together with the irradiation control device 314 to irradiate the particle beam toward the patient 40 (step S104). ..

Next, the central control device 312 determines whether or not irradiation in all irradiation directions is completed (step S105). When irradiating the particle beam from the other irradiation field forming devices 31A and 31B, or when irradiating the particle beam with the angle of the patient 40 changed by changing the inclination angle of the bed 33, it is determined that the process is not completed. Then, the process is returned to step S103, the irradiation field forming devices 31A and 31B are selected, the bed inclination angle is changed if necessary, and the particle beam is irradiated again in step S104. On the other hand, when it is determined that the process is completed, the process proceeds to step S106.

When it is determined in step S105 that the irradiation from all the planned irradiation directions is completed, the irradiation is terminated, and the patient 40 descends from the bed 33 and leaves the treatment room 30 (step S106).

Next, the positioning process of the bed 33 in step S102 of FIG. 4, which includes the method of positioning the bed 33 of the present invention, will be described in detail with reference to the flow chart of FIG.

As shown in FIG. 5, the patient first lays down on the bed and performs temporary positioning that reproduces the same posture as when the reference CT image was taken (step S201). In this temporary positioning, it is desirable to reproduce the positions of both arms, the angle at which the knees are bent, and the like using a support tool fixed to the bed 33. Move the bed 33 to an approximate position where the target position coincides with the isocenter.

After moving the bed, the positioning control device 311 may be retracted from the X-ray fluoroscope (X-ray generators 35A, 35B and X-ray receivers 36A, 36B) from the particle beam path, that is, the X-ray fluoroscopy position. Move the retracted X-ray generators 35A and 35B and X-ray receivers 36A and 36B to positions where X-ray fluoroscopic images can be captured, and capture X-ray fluoroscopic images with all four X-ray fluoroscopic devices. (Step S202). When the operator inputs an X-ray fluoroscopy command from the console 315, the positioning control device 311 that receives the command controls the X-ray generators 35A, 35B, 35C, and 35D to generate X-rays, and X-rays are generated. The X-ray fluoroscopic images detected by the receivers 36A, 36B, 36C, and 36D are collected.

Next, the positioning control device 311 determines whether or not it is necessary to take an image at another bed inclination angle (step S203). If it is necessary to take an image at another bed tilt angle, it is determined that fluoroscopy at all bed angles is not completed, and the process proceeds to step S204. On the other hand, when it is determined that fluoroscopy at all bed angles is completed, the process proceeds to step S205.

After it is determined that the position is not completed, in step S204, the operator inputs the bed tilt angle to the console 315 and sends a command to change the bed tilt angle from the console 315. Upon receiving the command, the positioning control device 311 controls the bed drive device 34 to change the angle of the bed 33 (step S204).

For example, it is assumed that fluoroscopy is performed at an inclination angle of the bed 33 of 0 degrees, -15 degrees, and 15 degrees. After first completing the X-ray fluoroscopy at 0 degrees of the bed, it is necessary to perform the X-ray fluoroscopy at the bed tilt angles of -15 degrees and 15 degrees, so the bed tilt angle is set to -15 degrees in step S204. do. The bed tilt angle is set so that the bed 33 is tilted with the straight line passing through the isocenter as the axis of rotation, parallel to the body axis direction of the patient. After tilting the bed 33, an X-ray fluoroscopic image is taken by all the X-ray fluoroscopic devices in step S202. Next, since it is necessary to perform X-ray fluoroscopy at a bed tilt angle of 15 degrees, the process transitions again from step S203 to step S204, the bed tilt angle is set to 15 degrees, and the bed 33 is tilted. Then, in step S202, an X-ray fluoroscopic image is taken by the X-ray fluoroscopic device. As described above, four X-ray fluoroscopic images are imaged at each of the three angles, and a total of 12 X-ray fluoroscopic images are acquired.

By repeating steps S202 to S204, a plurality of radiation fluoroscopes whose positions are fixed at least during the acquisition of a fluoroscopic image with respect to the image pickup target placed stationary on the bed 33 configured to be tilted from the horizontal direction. Corresponds to the acquisition step of acquiring a fluoroscopic image at a plurality of bed tilt angles using the above.

In these steps S203 and S204, the method is not limited to the method in which the operator inputs a command from the console 315 each time the bed inclination angle is changed as described above, and the bed inclination angle is determined before the start of acquisition of the X-ray fluoroscopic image. By setting in advance on the input screen as shown in the above and inputting the X-ray fluoroscopic image acquisition command from the console 315 by the operator, the command can be automatically executed in sequence. In addition to that, it may be automatically carried out sequentially based on the bed inclination angle set in advance according to the characteristics of the device without inputting from the console 315.

Here, for the sake of simplicity, the case where the bed 33 has three tilt angles has been described, but by further increasing the tilt angles, the image quality of the irradiated CT image reconstructed in step S205 is improved, and the positioning accuracy is improved. Can be improved.

In addition, the order of the bed tilt angles for acquiring the X-ray fluoroscopic image does not matter, but if there is an angle that matches the angle at which the particle beam is irradiated among the plurality of bed tilt angles, the angle at which the particle beam is irradiated is used. It is preferable to obtain the X-ray fluoroscopic image last.

Further, when the tilt angle of the bed 33 is large, the position of the patient 40 may move, so it is desirable to set a constraint on the tilt angle of the bed 33.

After the acquisition of the X-ray fluoroscopic image by the inclination angle of the bed 33 set in advance is completed in this way, the positioning control device 311 reconstructs the CT image and creates a CT image (tomographic image) at the time of irradiation (step S205). .. For the reconstruction, 12 X-ray fluoroscopic images acquired in steps S202 to S204 are used.

When the reconstruction is completed, the positioning control device 311 displays the reconstructed irradiation CT image and the reference CT image on the console 315. The amount of movement of the bed 33 is calculated so that the two images displayed on top of each other match (step S206). The amount of movement of the bed 33 includes both translation and rotation, and each is expressed as three parameters. That is, the amount of movement is the amount of movement of the orthogonal xyz in each of the three axes and the rotation angle about each axis.

There is a method of optimizing the six parameters representing the movement amount so that the value representing the correlation indicating the degree of coincidence between the two images becomes smaller in the calculation of the movement amount. The values representing the correlation include, for example, the dispersion of pixel values and the amount of mutual information. Further, the operator can manually adjust the six parameters of the movement amount while checking how the CT at the time of irradiation and the reference CT overlap with the console 315.

The six parameters of the movement amount adjusted in this way are transmitted to the positioning control device 311. When the operator inputs a bed movement command on the console 315, the positioning control device 311 controls the bed driving device 34 to move the bed 33 by a specified movement amount (step S207).

These steps S206 to S207 correspond to a moving step of moving the position of the bed 33 based on the fluoroscopic image obtained by repeating steps S202 to S204.

By the above operation, the patient 40 can be moved to the position planned by the treatment planning device 501.

When the positioning of the patient is completed, it is confirmed whether the bed 33 has moved to the predetermined position (step S208), and the X-ray receivers 36A and 36B on the irradiation path of the particle beam move to the retracted position and position. Is completed.

Here, the case where the bed 33 is tilted with the straight line parallel to the body axis and the horizontal direction of the patient 40 as the rotation axis has been described, but the axis of the angle at which the patient 40 is tilted is the isocenter parallel to the anteroposterior direction of the patient 40. The bed 33 may be tilted about a straight line (perpendicular to the body axis and the horizontal direction) passing through the bed 33. In this case, since the bed 33 is kept horizontal, it is possible to acquire an X-ray fluoroscopic image without moving the position of the patient 40 at more angles, and it is possible to reconstruct a CT image at the time of irradiation with good image quality. There is an advantage that it can be done.

Further, the axis of the angle at which the patient 40 is tilted may be tilted about the straight line perpendicular to the body axis of the patient 40 and parallel to the horizontal direction. Further, the bed 33 may be tilted from the body axis of the patient 40 with a straight line perpendicular to or horizontal to the horizontal direction as an axis, or the bed may be tilted with the body axis and a straight line tilted with respect to the horizontal direction as an axis. You may tilt 33. In this way, it is possible to rotate around any one of the x-axis, the y-axis, and the z-axis.

Next, the effect of this embodiment will be described.

The radiotherapy apparatus of the present embodiment described above has a bed 33 for standing the patient 40 and its positioning, which is configured to allow at least one of tilting from a horizontal direction and rotation in a horizontal plane. It is equipped with a bed positioning device to perform. Of these, the bed positioning device is a radiation fluoroscope consisting of X-ray generators 35A, 35B, 35C, 35D and X-ray receivers 36A, 36B, 36C, 36D, which acquire a fluoroscopic image of the patient 40 on the bed 33. A plurality of radiation fluoroscopes whose positions are fixed during acquisition of the fluoroscopic image, and a positioning control device 311 having a function of moving the position of the bed 33 based on the fluoroscopic image acquired by the radiation fluoroscope. , And the positioning control device 311 acquires a fluoroscopic image at a plurality of bed tilt angles, and executes control to move the position of the bed 33 based on the obtained plurality of fluoroscopic images.

Using the bed 33 configured to be able to change such an inclination angle, while sequentially changing the inclination angle of the bed 33, a plurality of X-ray fluoroscopic images are obtained by a plurality of X-ray fluoroscopes for each inclination angle of the bed 33. Since it is acquired, it is not necessary to move the structure for moving the X-ray fluoroscope or the X-ray fluoroscope when acquiring the fluoroscopic image, and the amount of movement of the structure for moving the fluoroscope or the X-ray fluoroscope is compared with the conventional one. Can be significantly reduced. Therefore, the problem of interference between the fluoroscopy device and other structures such as the irradiation field forming device can be solved as compared with the conventional case, and a space for retracting the structure for moving the fluoroscopy device or the X-ray fluoroscopy device. It is not necessary to secure a large amount of space, and the problem of space can be solved as compared with the conventional case. Further, it is possible to acquire an X-ray fluoroscopy image from a plurality of angles without arranging the X-ray fluoroscope in the rotation mechanism, and even when there is no rotation mechanism of the X-ray fluoroscope, highly accurate positioning can be performed. The effect that it is possible is obtained.

Further, since the radiation fluoroscope is composed of X-ray generators 35A, 35B, 35C, 35D for acquiring a fluoroscopic image by X-rays and X-ray receivers 36A, 36B, 36C, 36D, it has a simple configuration. Therefore, the accuracy of the fluoroscopic image required for positioning can be made high, and more accurate positioning becomes possible. In some cases, an X-ray generator or an X-ray receiver that has a different purpose can be used, so that there is no need to add a new structure for acquiring an X-ray fluoroscopic image, and there is no need for interference or space. It also has the effect of being able to solve the problem of.

Further, the positioning control device 311 calculates the amount of movement of the bed 33 using the tomographic image reconstructed from the fluoroscopic image, so that the position of the soft tissue close to the density of water can be determined in addition to the dense substance such as bone. The position of the bed 33 can be confirmed and determined, and more accurate positioning becomes possible.

Further, when the positioning control device 311 has an angle that matches the angle of irradiating the radiation among the plurality of bed inclination angles, the positioning control device 311 is requested to finally acquire the fluoroscopic image at the angle that matches the angle of irradiating the radiation. By controlling the bed inclination angle, irradiation of the particle beam can be started immediately after the positioning is performed, and the overall throughput of irradiation can be improved.

Further, the positioning control device 311 displays the bed tilt angle input screen 710 for inputting a plurality of bed tilt angles on the console 315, so that the tilt angle of the bed 33 according to the position of the target and the state of the patient 40 can be determined. The setting and its confirmation become easy, and the accuracy and the degree of freedom of the setting for acquiring the X-ray fluoroscopic image can be improved.

<Others>
The present invention is not limited to the above embodiment, and various modifications and applications are possible. The above-mentioned examples have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations.

For example, the method of calculating the amount of movement of the bed is not limited to the method of comparing the reference CT image and the irradiation CT image as described in steps S205 to S206 described above, and the reference fluoroscopic image is calculated from the reference CT image. The amount of movement can be calculated by comparing the created and obtained reference perspective image with the X-ray perspective image acquired by the X-ray fluoroscope. According to the present invention, there is an effect that the positioning accuracy is improved because the comparison direction is increased as compared with the conventional method of comparing fluoroscopic images at one bed inclination angle.

In addition, as a method for calculating the amount of movement of the bed, a reference fluoroscopic image at a plurality of angles is calculated from the reference CT image, a reference fluoroscopic image that most closely matches the fluoroscopic image acquired by the X-ray fluoroscope is selected, and then the bed 33 is used. There is a method to calculate the amount of movement. By selecting the most matching reference image, the amount of rotation with the patient's body axis as the rotation axis can be calculated accurately. According to the present invention, since the X-ray fluoroscopic image is acquired at a plurality of bed inclination angles, the comparison direction is increased even when this method is used, so that the positioning accuracy is improved.

Further, in the above-described embodiment, the configuration in which the irradiation field forming device and the X-ray fluoroscopy device of the particle beam therapy device are fixed has been described, but the irradiation field forming device and the X-ray fluoroscopy device are rotated around the patient 40. The present invention can also be applied to a particle beam therapy device provided with a rotation mechanism. In this case, the method for positioning the bed 33 of the present invention is performed by sequentially changing the bed tilt angle and acquiring X-ray fluoroscopic images at a plurality of bed tilt angles while the rotation mechanism of the X-ray fluoroscope is stopped. Can be carried out. According to the present invention, it is possible to perform highly accurate positioning without rotating the rotation mechanism that rotates the irradiation field forming device and the X-ray fluoroscopy device. When the irradiation field forming device and the patient fixative interfere with each other due to the rotation of the rotation mechanism, the rotation mechanism cannot be rotated, so that the positioning of the bed 33 according to the present invention is effective.

Further, in the above-described embodiment, the method of positioning using an X-ray fluoroscopic image has been described, but it is possible to acquire an image of a particle beam and perform positioning based on the image. Hereinafter, the outline of the particle beam therapy apparatus for acquiring the positioning image by the particle beam will be described with reference to FIG. FIG. 6 shows the configuration of the treatment room when positioning is performed using a fluoroscopic image acquired by a particle beam.

As shown in FIG. 6, in the particle beam therapy device that acquires a positioning image by a particle beam, a particle beam detector 38A is installed in the treatment room at a position opposite to the irradiation field forming device 31A with respect to the patient 40. The particle beam detector 38B is arranged at a position opposite to the forming device 31B. In this case, the radiation fluoroscope is a pair of the irradiation field forming device 31A and the particle beam detector 38A, and a pair of the irradiation field forming device 31B and the particle beam detector 38B, for a total of two irradiation field forming devices and the particle beam detector. It is a fluoroscope that is composed of a pair of particles and acquires a fluoroscopic image by a particle beam.

In order to obtain a positioning image by a particle beam, a small amount of a particle beam having a sufficiently high energy is irradiated to penetrate the patient. The positioning control device 311A transmits an irradiation signal of a particle beam to the irradiation control device 314A for positioning, and the irradiation control device 314A irradiates the particle beam for positioning. The irradiated particle beam is emitted from the irradiation field forming devices 31A and 31B, passes through the patient 40, and reaches the particle beam detectors 38A and 38B. Since the particle beam travels while attenuating the energy in the patient's body and reaches the particle beam detectors 38A and 38B, it can be seen that the position where the energy of the particle beam is low has a high density on the passage path. From this, the particle beam detectors 38A and 38B can obtain a fluoroscopic image by measuring the energy of the particle beam at each position on a plane perpendicular to the beam axis.

The nuclides of the particle beam for which the fluoroscopic image is acquired and the particle beam used for the treatment may be the same or different. If they match, the charged particle beam generator handles few nuclides, so there is an advantage that the configuration is simple. On the other hand, when the nuclides are different, there is an advantage that a fluoroscopic image can be obtained even when the patient 40 is large by using a nuclide having a small mass number and being easily transmitted.

As in the case of the fluoroscopic image by X-ray, the particle beam is sequentially irradiated from both the horizontal and upward irradiation field forming devices 31A and 31B at a plurality of bed inclination angles, and the fluoroscopic image of the particle beam is acquired. .. The tomographic image is reconstructed from the acquired fluoroscopic image and compared with the reference CT image to calculate the amount of movement of the bed 33. The bed 33 is moved by the calculated movement amount to complete the positioning. As the method of reconstruction and the method of calculating the movement amount of the bed 33, the same method as in the case of using X-rays can be used.

Further, the present invention can be applied to an X-ray therapy apparatus other than the above-mentioned particle beam therapy apparatus. FIG. 7 shows an example of the configuration of the treatment room of the X-ray treatment apparatus to which the present invention is applied.

As shown in FIG. 7, the X-ray treatment device includes an X-ray irradiation device 50 that generates therapeutic X-rays and a positioning device. The X-ray irradiation device 50 includes a rotation mechanism 51 that can rotate around the patient 40. The positioning device includes a plurality of fixed X-ray generators 35C, 35D, X-ray receivers 36C, 36D, a bed 33, a bed drive mechanism (not shown), and a positioning control device 311B. Even in such a configuration, the positioning of the bed 33, which is a feature of the present invention, can be carried out by following the flow of FIG.

Further, in FIG. 7, an example of the rotating X-ray irradiation device 50 is shown, but the X-ray irradiation device is attached to the tip of the robot arm so that the affected area can be irradiated with therapeutic X-rays from any direction. Even if there is, the positioning of the present invention can be carried out in the same manner.

30 ... Treatment room 31A, 31B ... Irradiation field forming device 33 ... Bed 34 ... Bed driving device 35A, 35B, 35C, 35D ... X-ray generator 36A, 36B, 36C, 36D ... X-ray receiver 38A, 38B ... Particle beam Detector 40 ... Patient 50 ... X-ray irradiation device 51 ... Rotation mechanism 311, 311A, 311B ... Positioning control device 312 ... Central control device 314, 314A ... Irradiation control device 315 ... Console 501 ... Treatment planning device 710 ... Bed tilt angle input screen

Claims (10)

With a bed configured to allow at least one of horizontal tilt and horizontal rotation,
A plurality of radiation fluoroscopes that acquire a fluoroscopic image of an imaged object on the bed and whose positions are fixed during acquisition of the fluoroscopic image.
A positioning control device having a function of moving the position of the bed based on a fluoroscopic image acquired by the radiation fluoroscopy device is provided.
The positioning control device acquires a perspective image at a plurality of bed tilt angles, executes control to move the position of the bed based on the obtained plurality of perspective images, and emits radiation into the plurality of bed tilt angles. If there is an angle that matches the angle of irradiation, the tilt angle of the bed is controlled so that the fluoroscopic image is finally acquired at the angle that matches the angle of irradiation.
A radiation therapy device characterized by that. In the radiotherapy apparatus according to claim 1,
The radiological fluoroscopy device is a radiotherapy device characterized in that it is a fluoroscopy device that acquires the fluoroscopic image by X-rays. In the radiotherapy apparatus according to claim 1,
The radiological fluoroscopy device is a radiotherapy device characterized in that it is a fluoroscopy device that acquires the fluoroscopic image by a particle beam. In the radiotherapy apparatus according to claim 1,
The positioning control device is a radiotherapy device characterized in that the amount of movement of the bed is calculated using a tomographic image reconstructed from the fluoroscopic image. In the radiotherapy apparatus according to claim 1,
The positioning control device is a radiotherapy device characterized in that a display device displays an input screen of the plurality of bed tilt angles. A bed positioning device for positioning a bed for allowing a radiation target to stand still, which is configured to allow at least one of tilting from a horizontal direction and rotation in a horizontal plane.
A plurality of radiation fluoroscopes that acquire a fluoroscopic image of an imaged object on the bed and whose positions are fixed during acquisition of the fluoroscopic image.
A positioning control device having a function of moving the position of the bed based on a fluoroscopic image acquired by the radiation fluoroscopy device is provided.
The positioning control device acquires a perspective image at a plurality of bed tilt angles, executes control to move the position of the bed based on the obtained plurality of perspective images, and emits radiation into the plurality of bed tilt angles. If there is an angle that matches the angle of irradiation, the tilt angle of the bed is controlled so that the fluoroscopic image is finally acquired at the angle that matches the angle of irradiation.
A bed positioning device characterized by that. Multiple radiations that are fixed in position at least during fluoroscopic image acquisition for an imaged object that is stationary on a bed that is configured to allow at least one of horizontal tilt and horizontal rotation. The acquisition process of acquiring fluoroscopic images at multiple bed tilt angles using a fluoroscopic device,
It has a moving step of moving the position of the bed based on the fluoroscopic image obtained by the acquisition step.
In the moving step, if there is an angle matching the radiation irradiation angle among the plurality of bed tilt angles, the perspective image at the angle matching the radiation irradiation angle is finally acquired. A bed positioning method characterized by controlling the tilt angle . In the bed positioning method according to claim 7 ,
In the acquisition step, a method for positioning a bed is characterized in that a fluoroscope that acquires the fluoroscopic image by X-rays is used as the radiation fluoroscope. In the bed positioning method according to claim 7 ,
In the acquisition step, a method for positioning a bed is characterized in that a fluoroscope that acquires the fluoroscopic image by a particle beam is used as the radiation fluoroscope. In the bed positioning method according to claim 7 ,
In the moving step, a bed positioning method characterized in that the moving amount of the bed is calculated using a tomographic image reconstructed from the fluoroscopic image acquired in the acquisition step.

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