JP7451285B2 - radiation therapy equipment - Google Patents

Description

Embodiments disclosed herein and in the drawings relate to radiation therapy apparatus.

Conventionally, in radiotherapy, first, rough alignment is performed between marks made on the body surface of the patient (subject to be treated) and a laser sight in the radiotherapy equipment based on the treatment plan, and then X-ray stereography is performed. Alignment between the radiation irradiation area and the iso-center of the radiation therapy apparatus is performed using an image or a cone beam CT image. Thereafter, the target area is irradiated with radiation, but it takes some time from alignment to irradiation of the irradiation area. During this time, the patient being treated is required to remain still, but it is difficult to hold their breath for long periods of time, and their position may move slightly.

Ideally, it would be desirable to treat the patient with a positional deviation of 0, but it is extremely difficult to achieve this, and alignment is performed many times in order to reduce the positional deviation to 0. This increases the treatment time and puts a burden on the patient. Therefore, after alignment between the irradiation area and the isocenter is performed, radiation is irradiated without assuming that the patient is moving unless the patient's posture changes significantly.

Regarding positional deviation due to breathing, for example, positional deviation is reduced by holding the breath at the end of exhalation and then irradiating radiation, but some positional deviation occurs even at the end of the same exhalation.

Such positional deviation causes a deviation in the radiation dose distribution between the treatment plan and the actual irradiation, but this deviation is ignored by existing methods. Specifically, in existing methods, a margin is added to the irradiation area so that sufficient radiation can be irradiated to the irradiation area even if there is such a shift.

Furthermore, conventionally, there is a system for measuring the shape of the body surface of a subject, and this system is used to check the movement (body movement, respiratory movement, etc.) of the subject during treatment. This system for measuring the surface shape of the object to be treated is, for example, a method in which images are taken from two directions with a twin-lens camera, and a three-dimensional shape is identified from the images from the two directions using the principle of stereo, or a method in which a three-dimensional shape is identified from one direction. There is a method of identifying a three-dimensional shape by irradiating a laser and photographing a laser projection image from the other side. Furthermore, a method of identifying a three-dimensional shape based on signals such as ultrasound waves is also known.

JP 2019-10508 Publication

One of the problems that the embodiments disclosed in this specification and drawings aim to solve is to reduce unnecessary radiation exposure. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problems. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems.

The radiation therapy apparatus according to the embodiment includes a first acquisition section, a second acquisition section, and an identification section. The first acquisition unit acquires first shape information indicating the body surface shape of the subject at the time of positioning before radiation irradiation. The second acquisition unit acquires second shape information indicating the body surface shape of the subject at the time of radiation irradiation. The identification unit identifies a change in the position of the radiation irradiation target area based on the first shape information and the second shape information.

FIG. 1 is a diagram showing an example of the configuration of a radiation therapy system according to a first embodiment. FIG. 2 is an external view showing an example of the radiation therapy apparatus according to the first embodiment. FIG. 3 is a diagram showing an example of the configuration of the radiation therapy apparatus according to the first embodiment. FIG. 4 is a flowchart showing a processing procedure by the radiation therapy apparatus according to the first embodiment. FIG. 5 is a diagram for explaining an example of processing by the identification function according to the modification.

Embodiments of the radiation therapy apparatus according to the present application will be described in detail below with reference to the accompanying drawings. Note that the radiation therapy apparatus according to the present application is not limited to the embodiments described below. Further, the embodiment can be combined with other embodiments or conventional techniques as long as there is no contradiction in processing content.

(First embodiment)
First, a radiation therapy system including a radiation therapy apparatus according to this embodiment will be described. FIG. 1 is a diagram showing an example of the configuration of a radiation therapy system 1 according to the first embodiment. As shown in FIG. 1, the radiation therapy system 1 according to the first embodiment includes a treatment planning CT (Computed Tomography) device 100, a treatment planning device 200, a radiation therapy information system 300, and a surface shape measuring device 400. and a radiation therapy apparatus 500. The treatment planning CT device 100, the treatment planning device 200, the radiation therapy information system 300, the surface shape measuring device 400, and the radiation therapy device 500 are connected to each other via the network 2 so that they can communicate with each other. Note that the configuration shown in FIG. 1 is just an example, and the embodiment is not limited to this. For example, the radiation therapy system 1 may include various other devices and systems.

The treatment planning CT device 100 has a pedestal, a bed device having a top plate, and a console, and collects CT image data including a treatment target site (tumor, etc.) of a patient lying on the top plate. , transmits the collected CT image data to the treatment planning device 200. Specifically, the treatment planning CT apparatus 100 collects projection data while rotating an X-ray tube and an Reconstruct three-dimensional CT image data. Here, the top plate of the treatment planning CT apparatus 100 has a planar shape similar to the top plate of the radiation therapy apparatus.

Note that in this embodiment, only the treatment planning CT apparatus 100 is shown as a device that collects image data for treatment planning, but the embodiment is not limited to this. For example, three-dimensional image data for treatment planning may be collected by a treatment planning MRI (Magnetic Resonance Imaging) device, an ultrasonic diagnostic device, or the like.

The treatment planning device 200 uses the three-dimensional CT image data of the subject collected by the treatment planning CT device 100 to create a treatment plan for radiation therapy by the radiation treatment device 500. For example, the treatment planning device 200 uses CT image data collected by the treatment planning CT device 100 to identify the position of the treatment target region within the patient's body. For example, the treatment planning device 200 also determines the irradiation angle of the radiation that the radiation therapy device 500 irradiates to the treatment target site whose position is specified using CT image data, the dose for each irradiation angle, and the shape of the irradiation field. Make a plan such as the number of times to irradiate. Then, the treatment planning device 200 transmits the treatment plan to the radiation treatment information system 300 and the radiation treatment device 500.

The radiation therapy information system 300 stores and manages various information related to radiation therapy. Specifically, the radiation therapy information system 300 collects various information related to treatment progress for each patient, such as treatment plans, performance information (irradiation history), various reports, and records of the status of the patient. be stored and managed. The radiation therapy information system 300 can provide information that is accessed and managed by each device connected to the network 2.

The surface shape measuring device 400 is installed in a treatment room, measures the shape of the body surface of a patient lying on the top plate of the radiation therapy device 500, and collects three-dimensional shape data of the body surface. Then, the surface shape measurement device 400 transmits the collected three-dimensional shape data to the radiation therapy device 500. Specifically, the surface shape measuring device 400 measures three-dimensional shape data of the body surface from the time when the subject is lying down on the table top and positioning for radiation therapy is performed until the end of the radiation therapy. Continue to collect. Here, the surface shape measuring device 400 can be realized by various techniques.

For example, the surface shape measuring device 400 includes a two-lens camera (stereo camera), and photographs the object to be treated from two directions using the stereo camera. Then, the surface shape measuring device 400 extracts corresponding pixels (pixels indicating the same position of the object to be treated) in the two image data taken from two directions. The surface shape measuring device 400 calculates the distance to each position on the body surface of the treated object using the difference in position between each corresponding pixel and the difference in the shooting position of the stereo camera. The three-dimensional coordinates of each position on the body surface are calculated. Note that corresponding pixels in two image data can be extracted using various existing matching algorithms. Thereby, the surface shape measuring device 400 can collect three-dimensional shape data of the body surface of the subject to be treated.

Further, for example, the surface shape measuring device 400 includes a light projection device that emits a laser and a camera. Then, the surface shape measuring device 400 uses a light projection device to scan the object to be treated on the top plate in a line shape with a laser, and captures the laser light as an image. Furthermore, the surface shape measuring device 400 calculates three-dimensional coordinates from the position of the laser light source and the position of the laser beam on the image. The surface shape measuring device 400 can collect three-dimensional shape data of the body surface of the subject by repeatedly performing this operation while changing the projection angle of the laser.

Note that the collection of three-dimensional shape data of the body surface is not limited to the above two methods, and any method may be used as long as the body surface of the subject can be measured.

The radiation therapy apparatus 500 irradiates a treatment subject with radiation according to the treatment plan by the treatment planning apparatus 200 to perform radiation treatment. FIG. 2 is an external view showing an example of the radiation therapy apparatus 500 according to the first embodiment. Note that FIG. 2 shows a radiation therapy apparatus 500 installed in a treatment room.

As shown in FIG. 2, the radiation therapy apparatus 500 includes a pedestal having a radiation generator 512, a radiation diaphragm 513, an imaging device (an X-ray generator 511a and an X-ray detector 511b), and a top plate 522. It includes a bed apparatus having a bed apparatus, and performs radiation therapy based on control from a console (not shown). Specifically, the radiation therapy apparatus 500 acquires a treatment plan from the radiation therapy information system 300. The radiation therapy apparatus 500 then rotates the pedestal in the direction of the arrow to set the irradiation angle in accordance with the treatment plan, and irradiates the subject lying on the top plate 522 with radiation.

Here, in radiotherapy, first, three-dimensional CT image data necessary for creating a treatment plan is collected by the treatment planning CT apparatus 100. Here, a fixture may be created to improve the reproducibility and maintainability of the posture of the subject. In addition, the body surface of the subject is marked with marks necessary for positioning in order to accurately irradiate the body with radiation during each radiation treatment session.

Then, in the treatment plan, the radiation irradiation area, the radiation irradiation angle, the dose for each irradiation angle, the shape of the irradiation field, the number of times of irradiation, etc. are determined. For example, in determining the radiation irradiation area, first, risk organs to be avoided from radiation irradiation are set based on CT image data collected by the treatment planning CT apparatus 100. Then, the gross tumor volume (GTV), which is a three-dimensional area in which the progression and presence of the tumor can be visually confirmed, is set, and the set GTV and the potential tumor area that cannot be confirmed macroscopically are set. A clinical target volume (CTV) is set. Note that the settings of risk organs, GTC, and CTV are performed, for example, by contouring (contour extraction), but contouring can be performed either manually by a doctor or automatically by image processing technology. .

In determining the radiation irradiation area, we use an ITV (internal target volume), which includes an internal margin (IM) to absorb the effects of internal organ movements such as breathing, swallowing, heartbeat, and peristalsis. is set for CTV. Furthermore, a planning target volume (PTV) including a set-up margin (SM) in each irradiation is set for the CTV, thereby determining the radiation irradiation area.

In this way, once the radiation irradiation area is determined, the radiation irradiation conditions for the determined irradiation area are set. For example, in the treatment planning device 200, an operator (medical worker) sets irradiation conditions such as the radiation irradiation angle, the dose for each irradiation angle, the shape of the irradiation field, and the number of irradiations. Here, the shape of the irradiation field is formed by, for example, a multi-leaf collimator (MLC), which is the radiation diaphragm 513. MLC has multiple radiation shielding plates that set the radiation irradiation range, and each shielding plate is driven independently based on the treatment plan to create an irradiation field that matches the shape of the radiation irradiation area (PTV). can be formed.

The treatment plan created in this way is transmitted to the radiotherapy information system 300 and managed together with patient information, treatment history, etc. During radiotherapy, a treatment plan is transmitted from the radiotherapy information system 300 to the radiotherapy apparatus 500. The radiation therapy apparatus 500 irradiates the subject lying on the top plate 522 with radiation according to the received treatment plan.

Here, the laser beam from the laser sight is attached to the body surface of the treated subject so that the treated subject lying on the top plate 522 is in the same position as when the CT image data for treatment planning was collected. The patient's position, bed, etc. are adjusted so that the marks overlap, and rough positioning is performed.

Thereafter, in order to align the radiation irradiation area and the isocenter of the radiation therapy apparatus 500, the radiation therapy apparatus 500 uses a cone beam for alignment using an imaging device including an X-ray generator 511a and an X-ray detector 511b. Generate CT image data. For example, the radiation therapy apparatus 500 irradiates X-rays from the X-ray generator 511a while rotating the pedestal, collects projection data for an angle of 200 degrees or more, and creates a three-dimensional cone based on the collected projection data. Reconstruct beam CT image data.

The radiation therapy apparatus 500 uses the reconstructed cone beam CT image data and the CT image data for treatment planning to align the irradiation area and the isocenter. Note that the radiation therapy apparatus 500 can perform alignment using other methods than the above-described alignment using cone beam CT image data. For example, as shown in FIG. 2, two X-ray imaging devices 511c are installed in the treatment room as imaging devices. The radiation therapy apparatus 500 uses two X-ray imaging devices 511c to photograph a subject lying on a top plate 522, and generates a DRR ( The alignment of the irradiation area and the isocenter is performed by comparing the irradiation area with the isocenter (Digitally Reconstructed Radiograph). Note that the DRR is a virtual X-ray image obtained by projecting CT image data for treatment planning in two directions taken by two X-ray imaging devices 511c.

In this way, in radiation therapy, detailed positioning is performed in order to deliver radiation according to the treatment plan, but as mentioned above, even after positioning, slight changes occur in the body position, making it difficult to administer radiation. A margin is set in the area (PTV) to absorb them. Therefore, the radiation therapy apparatus 500 according to the present embodiment detects a change in the posture after alignment based on the shape of the body surface of the treated object acquired by the surface shape measuring device 400. As a result, the radiation therapy apparatus 500 can determine the deviation in the administered dose and modify the treatment plan based on the detected change when the deviation is large, thereby reducing the margin included in the irradiation area. , reducing unnecessary radiation exposure. Note that the surface shape measuring device 400 is installed in a treatment room, for example, as shown in FIG.

Details of the radiation therapy apparatus 500 according to this embodiment will be described below. FIG. 3 is a diagram showing an example of the configuration of the radiation therapy apparatus 500 according to the first embodiment. As shown in FIG. 3, the radiation therapy apparatus 500 includes a pedestal 510, a bed device 520, and a console 530.

The pedestal 510 includes an imaging device 511, a radiation generator 512, and a radiation diaphragm 513. The imaging device 511 includes an X-ray generator 511a and an X-ray detector 511b, and performs imaging for collecting cone beam CT image data of a treatment subject placed on a bed device 520 under the control of a console 530. I do. Specifically, the imaging device 511 is configured such that an X-ray generator 511a that irradiates X-rays for imaging and an X-ray detector 511b that detects X-rays for imaging face each other with the object to be treated in between. Placed. The imaging device 511 emits X-rays from the X-ray generator 511a while the gantry 510 is rotating, and detects the X-rays with the X-ray detector 511b, thereby obtaining projection data for an angle of 200 degrees or more. collect. Imaging device 511 transmits the collected projection data to console 530.

The radiation generator 512 includes an electron gun and an acceleration tube (not shown). The acceleration tube accelerates thermionic electrons generated from the electron gun and causes them to collide with a tungsten target to emit therapeutic radiation. The radiation diaphragm 513 is, for example, an MLC, and has a plurality of radiation shielding plates that set the irradiation range of therapeutic radiation. For example, the radiation diaphragm 513 irradiates radiation having a shape corresponding to the irradiation area of the treated object by independently moving a plurality of radiation shielding plates using a moving mechanism (not shown) under control from the console 530. form a field.

The bed device 520 includes a base 521 and a top plate 522. The base 521 has a built-in bed driving device 523, and movably supports the top plate 522. The top plate 522 has a planar shape, and the subject to be treated is placed thereon. The bed driving device 523 includes a motor, an actuator, and the like, and moves the top plate 522 under the control of the console 530.

Console 530 includes a communication interface 531 , an input interface 532 , a display 533 , a storage circuit 534 , and a processing circuit 535 .

The communication interface 531 is connected to the processing circuit 535 and controls the transmission and communication of various data with each device connected via the network 2. For example, the communication interface 531 is realized by a network card, network adapter, NIC (Network Interface Controller), or the like.

The input interface 532 is connected to the processing circuit 535 , converts an input operation received from an operator (medical worker) into an electrical signal, and outputs the electrical signal to the processing circuit 535 . Specifically, the input interface 532 converts an input operation received from the operator into an electrical signal and outputs it to the processing circuit 535. For example, the input interface 532 includes a trackball, a switch button, a mouse, a keyboard, a touchpad that performs input operations by touching the operation surface, a touchscreen that integrates a display screen and a touchpad, and a non-control device that uses an optical sensor. This is realized by a touch input circuit, a voice input circuit, etc. Note that in this specification, the input interface 532 is not limited to one that includes physical operation parts such as a mouse and a keyboard. For example, examples of the input interface 532 include an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs this electrical signal to a control circuit.

The display 533 is connected to the processing circuit 535 and displays various information and various image data output from the processing circuit 535. For example, the display 533 is realized by a liquid crystal display, a CRT (Cathode Ray Tube) display, an organic EL display, a plasma display, a touch panel, or the like. In this embodiment, for example, the display 533 displays the treatment plan, irradiation history, and the like.

The storage circuit 534 is connected to the processing circuit 535 and stores various data. For example, the memory circuit 534 is realized by a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, a hard disk, an optical disk, or the like. For example, the storage circuit 534 stores surface shape information 5341, irradiation history 5342, and the like. Furthermore, the storage circuit 534 stores treatment plans received from the radiation therapy information system 300, various processing results, and the like.

The surface shape information 5341 is three-dimensional shape data of the body surface of the subject acquired by the surface shape measuring device 400. Specifically, the surface shape information 5341 is a plurality of three-dimensional shape data that are continuously collected after the object to be treated is aligned on the top plate 522 until the radiation treatment is finished. Each time the surface shape information 5341 is acquired by the surface shape measuring device 400, it is acquired by the processing circuit 535 and stored in the storage circuit 534.

The irradiation history 5342 includes the irradiation conditions and dose distribution of the radiation actually irradiated to the treated object, and is stored in the storage circuit 534 every time radiation irradiation is performed. Here, the irradiation history 5342 according to the present embodiment also includes irradiation conditions and dose distribution of radiation actually irradiated based on a treatment plan modified by a processing circuit 535, which will be described later. Note that the irradiation conditions will be detailed later. The irradiation history 5342 is transmitted to the radiation therapy information system 300 every time radiation irradiation is completed, and is managed by the radiation therapy information system 300.

The processing circuit 535 controls the overall operation of the radiation therapy apparatus 500 according to input operations received from the operator via the input interface 532. For example, processing circuit 535 is implemented by a processor. As shown in FIG. 3, the processing circuit 535 performs a control function 5351, an acquisition function 5352, an imaging function 5353, a reconstruction function 5354, an identification function 5355, and a modification function 5356. Here, the acquisition function 5352 is an example of a first acquisition unit and a second acquisition unit. Further, the identification function 5355 is an example of an identification unit. Further, the modification function 5356 is an example of a modification section.

The control function 5351 controls the execution of processes according to various requests input via the input interface 532. For example, the control function 5351 controls transmission and reception of information (eg, treatment plan, irradiation history, etc.) via the communication interface 531, storage of information in the storage circuit 534, display of information on the display 533, and the like.

Further, the control function 5351 controls the rotation of the pedestal 510, the irradiation of radiation by the radiation generator 512, the movement of the radiation shielding plate in the radiation diaphragm 513, etc. based on the treatment plan. Furthermore, the control function 5351 controls the movement of the top plate 522 by controlling the bed driving device 523 in the bed device 520 based on the treatment plan.

The acquisition function 5352 acquires shape information indicating the body surface shape of the subject to be treated from the surface shape measuring device 400. Specifically, the acquisition function 5352 acquires three-dimensional shape data (first shape information) of the body surface of the treated object indicating the shape of the body surface of the treated subject at the time of alignment before radiation irradiation. Further, the acquisition function 5352 acquires three-dimensional shape data (second shape information) indicating the body surface shape of the subject to be treated at the time of radiation irradiation. Here, the acquisition function 5352 acquires three-dimensional shape data (second shape information) indicating the body surface shape of the subject to be treated at least one of immediately before and during continuous radiation irradiation.

For example, the acquisition function 5352 transmits a control signal to the surface shape measuring device 400 to start measuring the body surface shape of the object to be treated on the top plate 522 when alignment is performed. The acquisition function 5352 sequentially acquires three-dimensional shape data acquired over time by the surface shape measuring device 400 and stores it in the storage circuit 534. The acquisition function 5352 continues to acquire three-dimensional shape data until radiation irradiation is completed. Note that the acquisition function 5352 temporarily stops the acquisition of the three-dimensional shape data after acquiring the three-dimensional shape data during positioning, and starts acquiring the three-dimensional shape data immediately before or after the start of radiation irradiation. It can also be controlled to restart.

The imaging function 5353 controls the imaging device 511 to collect projection data for reconstructing cone beam CT image data. Specifically, the imaging function 5353 controls rotation of the pedestal 510, irradiation of X-rays by the X-ray generator 511a, and data collection by the X-ray detector 511b. For example, the imaging function 5353 rotates the pedestal 510 by 200 degrees or more, causes the X-ray generator 511a to irradiate X-rays, and collects data with the X-ray detector 511b. Collect projection data for angles greater than or equal to degrees. The imaging function 5353 then stores the collected projection data in the storage circuit 534.

Furthermore, when two X-ray imaging devices 511c are installed in the treatment room, the imaging function 5353 controls the two X-ray imaging devices 511c to collect X-ray images in two directions, and The X-ray image is stored in the storage circuit 534.

The reconstruction function 5354 generates various images from the projection data collected by the imaging function 5353 and stores the generated images in the storage circuit 534. For example, the reconstruction function 5354 reconstructs cone beam CT image data by reconstructing projection data using various reconstruction methods, and stores the reconstructed cone beam CT image data in the storage circuit 534.

The identification function 5355 identifies the positional relationship between the isocenter and the radiation irradiation area in the radiation therapy apparatus 500 based on the image data. For example, the identification function 5355 compares the CT image data collected by the treatment planning CT apparatus 100 and the cone beam CT image data, and extracts the irradiation area in the cone beam CT image data. That is, the identification function 5355 extracts the position of the irradiation area in the coordinate system of the radiation therapy apparatus 500. The identification function 5355 identifies the positional relationship between the isocenter and the irradiation area in the radiation therapy apparatus 500. Furthermore, the identification function 5355 calculates six-axis parameters of the position and angle of the top plate 522 for aligning the irradiation area with respect to the isocenter based on the identified positional relationship.

For example, the identification function 5355 compares the X-ray images taken in two directions by the two X-ray imaging devices 511c and the DRR generated from the CT image data for treatment planning. Extract the position of the irradiation area in the coordinate system. The identification function 5355 identifies the positional relationship between the isocenter and the irradiation area in the radiation therapy apparatus 500, and provides six-axis parameters of the position and angle of the top plate 522 for aligning the irradiation area with respect to the isocenter. Calculate.

Further, the identification function 5355 identifies a change in the position of the irradiation area after alignment based on the three-dimensional shape data of the body surface of the subject. Specifically, the identification function 5355 identifies a change in the position of the irradiation region based on the three-dimensional shape data of the body surface collected during alignment and the three-dimensional shape data of the body surface collected during radiation irradiation. More specifically, the identification function 5355 uses the three-dimensional shape data of the body surface collected immediately after the completion of alignment as a reference, and the three-dimensional shape data of the body surface collected immediately before the start of radiation irradiation and the radiation radiation. Changes in position and shape from the reference of three-dimensional shape data of the body surface collected during irradiation are identified. Then, the identification function 5355 identifies a change in the position of the radiation irradiation area based on the identified change in the three-dimensional shape of the body surface.

For example, the identification function 5355 extracts the correspondence between each position on the body surface in the three-dimensional shape data collected during alignment and each position on the body surface in the three-dimensional shape data collected during radiation irradiation. That is, the identification function 5355 compares the coordinates of each position on the body surface during alignment in the coordinate system of the surface profile measuring device 400 with the coordinates of each position on the body surface during radiation irradiation, and identifies the same body surface position. Extract the change in the coordinates of .

For example, the identification function 5355 determines one body surface shape from the other body surface shape based on the three-dimensional shape data of the body surface collected during alignment and the three-dimensional shape data of the body surface collected during radiation irradiation. Non-rigid alignment is performed to match the irradiation area, and positional deviations and deformations of the irradiation area are identified based on the results of the non-rigid alignment. That is, in non-rigid positioning, the identification function 5355 identifies the positional shift of the irradiation area based on the movement of the body surface shape, and identifies the deformation of the irradiation area based on the deformation of the body surface shape.

For example, the identification function 5355 performs non-rigid alignment of the three-dimensional shape data of the body surface collected during alignment and the three-dimensional shape data of the body surface collected during radiation irradiation, without changing the body surface shape. If the position has moved, it is determined that a movement (positional shift) similar to the surface shape has occurred in the irradiation area. In addition, the identification function 5355 can detect, for example, that the shape of the body surface changes when non-rigid alignment is performed between the three-dimensional shape data of the body surface collected during alignment and the three-dimensional shape data of the body surface collected during radiation irradiation. If so, it is determined that a change related to a change in surface shape has occurred in the irradiated area.

Then, the identification function 5355 calculates the amount of positional shift and the amount of deformation of the irradiation area based on the result of the non-rigid alignment. For example, the identification function 5355 calculates the amount and direction of movement of the irradiation area with respect to the radiation irradiation direction based on the amount and direction of movement of each position on the body surface in non-rigid alignment. The identification function 5355 repeatedly performs the above-mentioned processing on the three-dimensional shape data of the body surface of the subject that is sequentially acquired during radiation irradiation, and continues to identify changes in the position and shape of the irradiation area. and do it.

In addition, in the example mentioned above, the case where the change of the irradiation area is identified directly using the change of three-dimensional shape data of a body surface was demonstrated. However, the embodiment is not limited to this, and for example, changes in the irradiation area may be identified using CT image data collected by the treatment planning CT apparatus 100.

Typically, three-dimensional CT image data collected for creating a treatment plan is collected in multiple time phases in order to take into account changes associated with respiration and pulsation. Therefore, the identification function 5355 extracts CT image data of two temporal phases whose temporal phases are close to each other from among the CT image data of multiple temporal phases collected for creating a treatment plan. The identification function 5355 then extracts each irradiation area included in the extracted two-time phase CT image data, and calculates the actual positional deviation and deformation amount of the irradiation area based on the change in the shape of the extracted irradiation area. calculate.

Modification function 5356 modifies the treatment plan based on the changes identified by identification function 5355. Specifically, the modification function 5356 changes the shape of the MLC during radiation irradiation to the treatment subject based on the change identified by the identification function 5355. For example, the correction function 5356 identifies a positional shift and a change in shape of the irradiation area in the radiation irradiation direction based on the movement amount and movement direction of the irradiation area with respect to the radiation irradiation direction. Then, the modification function 5356 changes the shape of the MLC so that the irradiation field matches the changed position and shape of the irradiation area. That is, the modification function 5356 controls the control function 5351 to change the shape of the MLC.

The modification function 5356 changes the shape of the MLC described above in accordance with changes in the position and shape of the irradiation area that are sequentially identified during radiation irradiation. Therefore, the radiation therapy apparatus 500 according to the present embodiment can correct the radiation irradiation field in real time in response to a positional shift and a change in shape of the irradiation area that occur during radiation irradiation. As a result, in the radiation therapy apparatus 500, the internal margin and the setup margin can be made small, and the exposure to radiation can be reduced.

Here, radiation irradiation in radiotherapy may be performed not only from one direction but also from multiple directions. Even in such a case, the radiation therapy apparatus 500 corrects the shape of the MLC in real time as described above when irradiating radiation from each direction.

Note that by correcting the shape of the MLC in real time, a difference may occur between the actual radiation dose distribution and the planned radiation dose distribution. In that case, the modification function 5356 can also modify the next treatment plan so that there is no difference between the actual radiation dose distribution and the planned radiation dose distribution. For example, in a treatment plan for 30 radiation irradiations, if there is a difference between the radiation dose distribution from the first radiation irradiation and the planned radiation dose distribution, the correction function 5356 may be used to Modify the irradiation plan. The modification function 5356 determines whether there is a difference in radiation dose distribution after each radiation irradiation, and can modify the irradiation plan each time if a difference occurs.

Then, the correction function 5356 stores the irradiation history in the storage circuit 534 after the radiation irradiation is completed. For example, the correction function 5356 includes the irradiation conditions of the actually irradiated radiation, the presence or absence of changes in the position and shape of the irradiation area, the amount of change in the position and shape of the irradiation area, the content of changes in the shape of the MLC, and the actual radiation dose distribution. With respect to changes in the position and shape of the irradiation area, an irradiation history including the radiation dose distribution and the like if the shape of the MLC were not changed is stored in the storage circuit 534.

In addition, the correction function 5356 does not correct the treatment plan in real time even if the position and shape of the irradiation area changes, but corrects the next treatment plan after performing radiation irradiation according to the treatment plan. You can also do that. That is, the modification function 5356 modifies the treatment plan for the next and subsequent times so as to correct the deviation in the radiation dose distribution caused by performing radiation irradiation according to the treatment plan.

Here, the modification function 5356 can selectively use the above-described real-time treatment plan modification and subsequent treatment plan modification depending on the degree of change in the irradiation area. Specifically, the modification function 5356 changes the shape of the MLC during irradiation of the treatment subject with radiation when the change in the irradiation area identified by the identification function 5355 is greater than a threshold value. That is, the modification function 5356 modifies the treatment plan in real time when the radiation dose distribution deviates significantly from the treatment plan due to a large change in the irradiation area. In addition, when the change in the irradiation area identified by the identification function 5355 is smaller than a threshold value, the correction function 5356 irradiates radiation with the position of the radiation irradiation target area changed and corrects the next treatment plan. do.

Hereinafter, an example of processing by the radiation therapy apparatus 500 will be described using FIG. 4. FIG. 4 is a flowchart showing a processing procedure by the radiation therapy apparatus 500 according to the first embodiment. Here, steps S101, S103 to S104 in FIG. 4 are realized, for example, by the processing circuit 535 reading out a program corresponding to the identification function 5355 from the storage circuit 534 and executing it. Further, step S102 is realized, for example, by the processing circuit 535 reading out a program corresponding to the acquisition function 5352 from the storage circuit 534 and executing it. Further, steps S105 to S107 and S109 to S111 are realized, for example, by the processing circuit 145 reading out a program corresponding to the correction function 5356 from the storage circuit 534 and executing it. Further, step S108 is realized, for example, by the processing circuit 535 reading out a program corresponding to the control function 5351 from the storage circuit 534 and executing it.

In the radiation therapy apparatus 500 according to the first embodiment, first, a medical staff places a patient to be treated on the top plate 522 and places the patient on the bed so that the mark made on the body surface matches the laser beam from the laser sight. Adjust device 520. The medical staff then rotates the pedestal 510 in the direction of the first radiation irradiation based on the treatment plan. When the rotation is completed and the pedestal 510 is set in the radiation irradiation direction, the imaging function 5353 controls the imaging device 511 to collect image data. For example, the imaging function 5353 controls the imaging device 511 to collect projection data for reconstructing cone beam CT image data. Alternatively, the imaging function 5353 controls the two X-ray imaging devices 511c to collect X-ray images in two directions.

When image data is collected in this way, the identification function 5355 performs alignment based on the image data, as shown in FIG. 4 (step S101). For example, the identification function 5355 compares CT image data collected by the treatment planning CT apparatus 100 with cone beam CT image data, and identifies the positional relationship between the isocenter and the irradiation area in the radiation therapy apparatus 500. Then, the identification function 5355 calculates six-axis parameters of the position and angle of the top plate 522 for aligning the irradiation area with respect to the isocenter based on the identified positional relationship.

Alternatively, the identification function 5355 can identify the isocenter in the radiation therapy apparatus 500 by comparing the X-ray images in two directions taken by the two X-ray imaging apparatuses 511c and the DRR generated from the CT image data for treatment planning. and the irradiation area, and calculate six-axis parameters of the position and angle of the top plate 522 for aligning the irradiation area with respect to the isocenter. Note that the identification function 5355 can also perform position alignment using cone beam CT image data and then further capture X-ray images in two directions to confirm the position.

When the alignment is performed as described above, the acquisition function 5352 starts acquiring three-dimensional shape data indicating the surface shape of the object to be treated on the top plate 522 (step S102). The identification function 5355 determines the three-dimensional shape data at the time of alignment as a reference shape (step S103), and compares the surface shape acquired thereafter with the reference shape (step S104). The identification function 5355 then determines whether a change has occurred in the shape (step S105).

Here, if there is no change in the shape of the body surface of the treated object (step S105, negative), the control function 5351 adjusts the tube voltage, tube current, irradiation time, and shape of the MLC according to the treatment plan, Radiation is irradiated (step S108).

On the other hand, when a change occurs in the shape of the body surface of the subject to be treated (step S105, affirmative), the identification function 5355 determines whether or not to modify the treatment plan in real time (step S106). For example, the identification function 5355 determines whether the amount of change in the shape identified by the identification function 5355 exceeds a threshold value.

Here, if the treatment plan is modified in real time (for example, the amount of change exceeds the threshold) (step S106, affirmative), the modification function 5356 modifies the shape of the MLC based on the change in shape (step S107). ) Then, the control function 5351 irradiates radiation using the tube voltage, tube current, and irradiation time according to the treatment plan and the changed MLC shape (step S108). Note that if the treatment plan is not modified in real time (for example, the amount of change does not exceed the threshold) (step S106, negative), the control function 5351 adjusts the tube voltage, tube current, irradiation time, and MLC shape according to the treatment plan. and irradiates with radiation (step S108).

When the irradiation is completed, the correction function 5356 stores the irradiation history in the storage circuit 534 (step S109), and determines whether all the irradiations have been completed (step S110). For example, the correction function 5356 determines whether irradiation from all irradiation angles in the first irradiation has been completed.

Here, if all the irradiation is not completed (step S110, negative), the control function 5351 rotates the gantry 510 to the next irradiation angle, and the process from step S104 is executed again. On the other hand, if all irradiations have been completed (step S110, affirmative), the modification function 5356 modifies the next treatment plan based on the irradiation history (step S111), and ends the process.

(Modified example)
In the embodiment described above, an example was described in which changes in the irradiation area are identified using CT image data collected by the treatment planning CT apparatus 100, but this CT image data may be collected in advance at a high collection rate. It is also possible to accurately identify changes in the irradiation area.

FIG. 5 is a diagram for explaining an example of processing by the identification function 5355 according to the modification. Here, in FIG. 5, the respiratory signal is shown in the upper row. The respiratory signal is obtained, for example, by a sensor that detects expansion and contraction of a wound around the chest or abdomen. That is, the sensor detects changes in chest circumference or abdominal circumference associated with breathing as a breathing signal. For example, the elongation detected by the sensor indicates that the chest or abdominal circumference has increased due to inspiration. Further, the contraction detected by the sensor indicates that the chest circumference or abdominal circumference has decreased due to exhalation. In other words, in Figure 5, the part where the curve goes down to the lower right corresponds to expiration, which is a series of phases of breathing out, and the part where the curve goes up to the upper right in Figure 5 corresponds to a series of phases of breathing in. Corresponds to inhalation.

For example, in radiation therapy, as shown in FIG. 5, radiation irradiation is controlled to be turned on at the end of exhalation and turned off at the start of inspiration. Therefore, when identifying changes in the irradiation area using CT image data collected by the treatment planning CT apparatus 100, it is preferable to use CT image data collected at the end of expiration when radiation irradiation is turned on. .

For example, as shown in FIG. 5, the identification function 5355 selects CT image data 11 and CT image data 12 of two temporal phases whose respiratory phases are close to each other from among a plurality of CT image data collected over the entire respiratory cycle. and extract. Then, the identification function 5355 determines the shape of the body during radiation irradiation based on the three-dimensional shape data of the body surface when the CT image data 11 was taken and the three-dimensional shape data of the body surface when the CT image data 12 was taken. Virtual CT image data 13 that substantially matches the three-dimensional shape data of the body surface is generated. That is, by using the CT image data 11 and CT image data 12, the identification function 5355 estimates the position and shape of the irradiation area during radiation irradiation, with reference to changes in the position and shape of the irradiation area that actually occur inside the body. do. Note that by performing such estimation, it is possible to correct not only the slight body movement targeted in the first embodiment described above, but also the deviation due to the deviation of the respiratory phase in the modified example.

In this manner, the identification function 5355 identifies changes in the irradiation area by estimating the position and shape of the irradiation area during radiation irradiation based on actual changes in the position and shape of the irradiation area. Therefore, by collecting CT image data at a higher acquisition rate from the end of expiration when radiation irradiation is turned on to the start of inspiration, it is possible to obtain more detailed changes in the position and shape of the actual irradiation area. This makes it possible to accurately identify changes in the irradiation area.

Here, for estimating changes in the position and shape of the irradiation area in consideration of respiratory movements, there are two possible methods: a method using the above-described sensor data, and a method not using the sensor data. In the case of the method using sensor data, the identification function 5355 identifies the time at the time of radiation irradiation from among the plurality of CT image data collected over the entire respiratory cycle, based on the time phase information acquired by the sensor. CT image data of two temporal phases in which the respiratory phases are close to each other are extracted. Then, the identification function 5355 compares the three-dimensional shape data of the body surface in the CT image data of two temporal phases in which the respiratory phases are close to the three-dimensional shape data of the body surface at the time of radiation irradiation, and applies the deviation due to breathing. Non-rigid deformation is applied to one of the two temporal phases of CT image data. The identification function 5355 estimates the deformation of the irradiation area based on the non-rigid deformation transformation. Furthermore, the identification function 5355 corrects positional deviation due to movement. In the case of this method, the deformation caused by breathing is slight, so if breathing does not deviate significantly, stable estimation can be performed in a short period of time.

Furthermore, in the case of a method that does not use sensor data, the identification function 5355 performs positioning of the head and pelvis as a reference with respect to a plurality of CT image data collected over the entire respiratory cycle. Then, the identification function 5355 extracts two CT image data whose chest and abdomen are closest in position from among the CT image data after alignment. Then, the identification function 5355 compares the three-dimensional shape data of the body surface in the two CT image data with the three-dimensional shape data of the body surface at the time of radiation irradiation, applies the deviation due to respiration, and calculates the two-time phase CT image data. Apply non-rigid deformation to one side of . The identification function 5355 estimates the deformation of the irradiation area based on the non-rigid deformation transformation. Furthermore, the identification function 5355 corrects positional deviation due to movement. In this method, it is assumed that deformation due to breathing is not reproducible, and the closest three-dimensional shape data is searched from all time phases. As a result, although the amount of calculation increases, it is possible to perform transformation using data whose phase is closest to that of respiration, and it becomes possible to perform estimation with high accuracy.

As described above, according to the first embodiment, the acquisition function 5352 acquires first shape information indicating the body surface shape of the treated object at the time of alignment before radiation irradiation. The acquisition function 5352 acquires second shape information indicating the body surface shape of the subject at the time of radiation irradiation. The identification function 5355 identifies a change in the position of the radiation irradiation target area based on the first shape information and the second shape information. Modification function 5356 modifies the treatment plan based on the changes identified by identification function 5355. Therefore, the radiation therapy apparatus 500 according to the first embodiment can modify the treatment plan according to changes in the position of the irradiation area, and can set the internal margin and the setup margin small. As a result, the radiation therapy device 500 allows for reduced radiation exposure to normal areas and also enables accurate dose administration to the target area.

Further, according to the first embodiment, the acquisition function 5352 acquires the second shape information indicating the body surface shape of the treated object at least either immediately before radiation irradiation or during radiation irradiation. Therefore, the radiation therapy apparatus 500 according to the first embodiment makes it possible to detect changes in the irradiation area after alignment.

Further, according to the first embodiment, the identification function 5355 performs non-rigid alignment of the first shape information and the second shape information to match one body surface shape to the other body surface shape. , identify displacement and deformation of the target region based on the results of the non-rigid alignment. Therefore, the radiation therapy apparatus 500 according to the first embodiment can detect changes in the irradiation area by a method that does not use radiation, and can prevent an increase in radiation exposure.

Further, according to the first embodiment, the identification function 5355 identifies the positional shift of the target region based on the movement of the body surface shape in non-rigid body alignment, and identifies the positional shift of the target region based on the deformation of the body surface shape. Identify deformities. Therefore, the radiation therapy apparatus 500 according to the first embodiment makes it possible to identify positional deviations and changes in shape of the irradiation area.

Further, according to a modification, the identification function 5355 is configured to identify a body in a plurality of three-dimensional image data including a target region collected over time from a treatment subject and a plurality of three-dimensional shape data of a plurality of body surfaces photographed at the same time. A plurality of three-dimensional image data showing changes similar to changes in the surface shape are extracted, and deformation of the target region is identified based on the extracted plurality of three-dimensional image data. Therefore, the radiation therapy apparatus 500 according to the first embodiment can identify positional deviations and changes in shape of the irradiation area based on actual positional deviations and changes in shape of the irradiation area, and provides highly accurate identification. enable.

Further, according to a modification, the plurality of three-dimensional image data are collected at least in each phase of one breath of the subject. Therefore, the radiation therapy apparatus 500 according to the first embodiment makes it possible to refer to the actual positional shift and change in shape of the irradiation area due to breathing.

Further, according to the modification, the plurality of three-dimensional image data are collected at a relatively high collection rate near the respiratory phase in which radiation is irradiated during one breath of the subject. Therefore, the radiation therapy apparatus 500 according to the modified example can refer to the actual positional deviation of the irradiation area and finer changes in shape, thereby enabling more accurate identification.

Further, according to the first embodiment and the modified example, the correction function 5356 uses a multi-leaf collimator (MLC) during radiation irradiation to the treatment subject based on the change identified by the identification function 5355. change the shape of. Therefore, the radiation therapy apparatus 500 according to the first embodiment enables real-time modification of the treatment plan.

Further, according to the first embodiment and the modification, the modification function 5356 changes the shape of the multi-leaf collimator during radiation irradiation to the treatment subject when the change identified by the identification function 5355 is larger than the threshold value. change. Therefore, the radiation therapy apparatus 500 according to the first embodiment can make corrections in real time when the position and shape of the irradiation area has changed significantly, reducing the time required for resetting, and improving the It makes it possible to reduce the load.

Further, according to the first embodiment and the modified example, the correction function 5356 adjusts the radiation dose distribution after radiation is irradiated with the position of the radiation irradiation target area changed and the radiation dose distribution in the treatment plan. Modify subsequent treatment plans based on the difference. Therefore, the radiation therapy apparatus 500 according to the first embodiment and the modified example allows modification of the entire treatment plan.

Further, according to the first embodiment and the modified example, when the change identified by the identification function 5355 is smaller than the threshold, the correction function 5356 irradiates the radiation target area with the position changed. and modify future treatment plans. Therefore, the radiation therapy apparatus 500 according to the first embodiment prevents excessive modification of the treatment plan during radiation irradiation, prevents the time required for radiation irradiation from increasing, and reduces the load on the treated subject. make it possible.

(Other embodiments)
Now, although the first embodiment has been described so far, it may be implemented in various different forms other than the first embodiment described above.

In the embodiment described above, a case has been described in which the modification function 5356 modifies the treatment plan based on the change identified by the identification function 5355. However, embodiments are not limited thereto; for example, the modification function 5356 may not modify the treatment plan. For example, the correction function 5356 compares the planned radiation dose distribution with the radiation dose distribution after the change identified by the identification function 5355, and if the deviation in the administered dose is within a threshold, the treatment plan is Irradiation may be performed as is without any modification.

In the embodiment described above, each processing function that the processing circuit 535 has has been described. Here, for example, each of the processing functions described above is stored in the storage circuit 534 in the form of a computer-executable program. The processing circuit 535 reads each program from the storage circuit 534 and executes each read program, thereby realizing a processing function corresponding to each program. In other words, the processing circuit 535 in a state where each program is read has each processing function shown in FIG. 3.

Note that although FIG. 3 describes an example in which each processing function is realized by a single processing circuit 535, the embodiment is not limited to this. For example, the processing circuit 535 may be configured by combining a plurality of independent processors, and each processor may implement each processing function by executing each program. Further, each processing function of the processing circuit 535 may be realized by being appropriately distributed or integrated into a single or multiple processing circuits.

Furthermore, the word "processor" used in the description of each embodiment described above refers to, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an Application Specific Integrated Circuit (ASIC). , circuits such as programmable logic devices (e.g., Simple Programmable Logic Devices (SPLDs), Complex Programmable Logic Devices (CPLDs), and Field Programmable Gate Arrays (FPGAs)). means. Here, instead of storing the program in the memory circuit, the program may be directly incorporated into the circuit of the processor. In this case, the processor implements its functions by reading and executing a program built into the circuit. Furthermore, each processor of this embodiment is not limited to being configured as a single circuit for each processor, but may also be configured as a single processor by combining multiple independent circuits to realize its functions. good.

Here, the program to be executed by the processor is provided by being pre-installed in a ROM (Read Only Memory), a storage unit, or the like. This program is a file in a format that can be installed or executable on these devices, such as CD (Compact Disk)-ROM, FD (Flexible Disk), CD-R (Recordable), DVD (Digital Versatile Disk), etc. may be stored and provided on a computer readable storage medium. Further, this program may be stored on a computer connected to a network such as the Internet, and may be provided or distributed by being downloaded via the network. For example, this program is composed of modules including each functional unit. In actual hardware, a CPU reads a program from a storage medium such as a ROM and executes it, so that each module is loaded onto the main storage device and generated on the main storage device.

According to at least one embodiment described above, unnecessary exposure can be reduced.

Although several embodiments have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, changes, and combinations of embodiments can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

500 Radiation therapy device 5352 Acquisition function 5355 Identification function 5356 Correction function

Claims (12)

a first acquisition unit that acquires first shape information indicating the body surface shape of the treated subject at the time of positioning when performing radiation irradiation;
a second acquisition unit that acquires second shape information indicating the body surface shape of the subject to be treated at the time of radiation irradiation;
an identification unit that identifies at least one of positional deviation and deformation of the radiation irradiation target area based on the first shape information and the second shape information;
A radiation therapy device comprising: The radiation therapy apparatus according to claim 1, further comprising a modification section that modifies the treatment plan based on at least one of positional deviation and deformation identified by the identification section. 3. The second acquisition unit acquires the second shape information indicating the body surface shape of the subject at least one of immediately before radiation irradiation and during radiation irradiation. radiotherapy equipment. The identification unit compares each position on one body surface with each corresponding position on the other body surface with respect to the first shape information and the second shape information, and identifies the same body surface position. The radiation therapy apparatus according to any one of claims 1 to 3, wherein non-rigid alignment is performed to align the positions of the target area, and positional deviation and deformation of the target region are identified based on the results of the non-rigid alignment. In the non-rigid alignment, the identification unit identifies a positional shift of the target region based on whether or not the body surface shape has moved position without a change in shape , and determines the shape of the body surface shape. The radiation therapy apparatus according to claim 4, wherein the deformation of the target region is identified based on whether or not the target region has changed . The identification unit extracts a plurality of three-dimensional image data showing a change similar to a change in the body surface shape from a plurality of three-dimensional image data including the target region collected from the subject to be treated over time. 5. The radiation therapy apparatus according to claim 4, wherein deformation of the target region is identified based on a plurality of extracted three-dimensional image data. The radiation therapy apparatus according to claim 6, wherein the plurality of three-dimensional image data are collected at least in each phase of one breath of the subject. 8. The radiation therapy apparatus according to claim 7, wherein the plurality of three-dimensional image data are collected at a relatively high collection rate near a respiratory phase in which radiation is irradiated during one breath of the treated subject. The radiation therapy according to claim 2, wherein the modification unit changes the shape of a multi-leaf collimator (MLC) during radiation irradiation to the treatment subject based on the change identified by the identification unit. treatment equipment. When at least one of the positional deviation and deformation identified by the identification unit is larger than a corresponding threshold of a threshold set for the positional deviation and a threshold set for the deformation, the correction unit The radiation therapy apparatus according to claim 9, wherein the shape of the multi-leaf collimator is changed during irradiation of the radiation to the treated object. The correction unit corrects the next treatment plan based on the difference between the radiation dose distribution after radiation is irradiated with the position of the radiation irradiation target area changed and the radiation dose distribution in the treatment plan. The radiation therapy apparatus according to claim 2. The correction unit controls radiation irradiation when the positional deviation and deformation identified by the identification unit are smaller than corresponding thresholds of a threshold set for the positional deviation and a threshold set for the deformation. The radiation therapy apparatus according to claim 11, wherein radiation is irradiated while the position of the target region is changed, and the treatment plan for the next and subsequent times is corrected.

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