Radiation treatment assistance device, radiation treatment assistance program, and radiation treatment system

Abstract

[Problem] To provide a radiation treatment assistance device, a radiation treatment assistance program, and a radiation treatment system capable of monitoring, in real time during radiation exposure, that a tumor moving due to respiration, heart movement, intestinal peristalsis, or the like remains in a planning target volume irradiated with a therapeutic radiation beam during MR-guided online-adaptive radiotherapy. [Solution] The present invention is provided with: a magnetic resonance image acquisition unit that acquires magnetic resonance image data of a region including the planning target volume of a therapeutic radiation beam; and an image synthesis unit that synthesizes preset contour image data for the magnetic resonance image data. The magnetic resonance image acquisition unit acquires first magnetic resonance image data that is a magnetic resonance image when the radiation is being radiated, and second magnetic resonance image data that is a magnetic resonance image when the radiation is not being radiated. The image synthesis unit synthesizes the second magnetic resonance image data and contour image data including image data of the contours of a gross tumor volume and image data of the contours of the planning target volume.

Description

Radiation therapy support device, radiation therapy support program, and radiation therapy system

[0001] The present invention relates to a radiation therapy support device, a radiation therapy support program, and a radiation therapy system.

[0002] Radiation therapy plays an important role in cancer treatment as one of the "three pillars of cancer treatment." In radiation therapy, it is important to understand the location of the target tumor.

[0003] MRI (Magnetic Resonance Imaging) images taken by an MR (Magnetic Resonance) device have better contrast resolution between normal tissue and tumors in soft tissue than images taken by X-ray CT (Computed Tomography). For this reason, MR devices are often used to confirm the location of tumors that have developed in soft tissue.

[0004] In recent years, MR linacs, which combine MR devices and linacs, have been used in clinical applications. A linac (linear accelerator) is a device that generates therapeutic radiation beams such as high-energy X-ray beams and electron beams by colliding linearly accelerated electrons or protons with metal. MR linacs can acquire MR images while irradiating the therapeutic radiation beam (during irradiation), making it possible to match the position of the tumor with the planned target volume to be irradiated with the therapeutic radiation beam.

[0005] The spatial extent of a targeted tumor is defined in ICRU (International Commission on Radiation Units and Measurements) Report 83 (Non-Patent Document 1). Gross tumor volume is the volume in which the presence of a tumor can be confirmed with the naked eye. The location and size of the gross tumor volume are determined by imaging diagnostics such as endoscopy, X-ray CT scans, MR scans, and ultrasound scans. The planning target volume is a target volume determined taking into account the uncertainties of radiation therapy.

[0006] MR image-guided real-time adaptive radiation therapy is a type of radiation therapy in which, while the patient is positioned on the treatment couch, three-dimensional MR images are acquired on the day of treatment, and based on the images, contouring is performed, a new treatment plan is created, verified, and delivered. In MR image-guided real-time adaptive radiation therapy using an MR linac, it is important to directly observe the tumor using MR images during irradiation with the therapeutic radiation beam and appropriately control the therapeutic radiation beam to confirm that the treatment is being delivered according to the treatment plan created just before treatment. Specifically, the macroscopic tumor volume is determined using MR images, and the linac's therapeutic radiation beam is controlled based on the planned target volume calculated using a treatment planning system.

[0007] Patent Document 1 discloses a method for reconstructing an MR image using a B-TFE (Balanced Turbo Field Echo) sequence, which is a high-speed imaging sequence.

[0008] Patent Document 2 discloses a configuration of an MR device combined with a linear accelerator, and a system for more quickly acquiring imaging slices by comparing information indicating a portion of a target trajectory obtained quickly from one or more imaging slices with information obtained from a previously acquired volume reference image.

[0009] Special table 2020-523075 publication Special table 2022-544780 publication

[0010] International Commission on Radiation Units and Measurements: Prescribing, Recording, and Reporting Proton-Beam Intensity-Modulated Radiation Therapy (IMRT), ICRU Report 83, Journal of the ICRU, Volume 10(1). Oxford University Press, 2010.

[0011] The tumor, which is the target of radiation irradiation, moves due to breathing, cardiac movement, intestinal peristalsis, etc. Therefore, the therapeutic radiation beam may significantly deviate from the planned target volume to be irradiated.

[0012] If the tumor position significantly shifts from the planned target volume to be irradiated with the therapeutic radiation beam, it is necessary to quickly stop the irradiation of the therapeutic radiation beam. This action prevents damage to areas other than the targeted tumor due to the irradiation of the therapeutic radiation beam. Therefore, it is important to check the tumor position in real time during irradiation of the therapeutic radiation beam.

[0013] For this reason, MR linacs use high-speed imaging sequences, such as B-TFE, that prioritize temporal resolution during irradiation of therapeutic radiation beams. However, high-speed imaging sequences have low contrast due to a shortened data update time. Therefore, high-speed imaging sequences have the problem that they cannot monitor in real time during irradiation of therapeutic radiation beams whether tumors that move due to breathing, cardiac movement, intestinal peristalsis, etc. remain within the planned target volume of the therapeutic radiation beam. In this regard, the techniques disclosed in Patent Document 1, Patent Document 2, and Non-Patent Document 1 have difficulty in solving the above-mentioned problem.

[0014] The present invention has been devised in consideration of the above-mentioned problems, and an object of the present invention is to provide a radiation therapy support device, a radiation therapy support program, and a radiation therapy system that are capable of monitoring in real time during irradiation of a therapeutic radiation beam to ensure that a tumor that moves due to breathing, cardiac movement, intestinal peristalsis, etc. remains within the planned target volume of the therapeutic radiation beam.

[0015] A radiation therapy support device according to a first aspect of the present invention is a radiation therapy support device used for MR image-guided real-time adaptive radiation therapy, and includes: a magnetic resonance image acquisition unit that acquires magnetic resonance image data of a region including a planned target volume to be irradiated with a therapeutic radiation beam; and an image synthesis unit that synthesizes predetermined contour image data with the magnetic resonance image data acquired by the magnetic resonance image acquisition unit, wherein the magnetic resonance image acquisition unit acquires first magnetic resonance image data which is a magnetic resonance image when the therapeutic radiation beam is being irradiated and second magnetic resonance image data which is a magnetic resonance image when the therapeutic radiation beam is not being irradiated, and the image synthesis unit synthesizes the contour image data including image data of the contour of a macroscopic tumor volume and image data of the contour of the planned target volume with the second magnetic resonance image data.

[0016] A radiation therapy support apparatus according to a second aspect of the present invention is the first aspect of the present invention, characterized in that the second magnetic resonance image data has a longer update time than the first magnetic resonance image data.

[0017] A radiation therapy support apparatus according to a third aspect of the present invention is the radiotherapy support apparatus of the first aspect, characterized in that the contour image data includes image data of the contours of organs at risk or image data of the contours of dose distribution.

[0018] A radiation therapy support device according to a fourth invention is the same as that of the first invention, characterized in that the magnetic resonance image acquisition unit alternately switches between acquiring the first magnetic resonance image data and acquiring the second magnetic resonance image data.

[0019] A radiation therapy support device according to a fifth aspect of the present invention is characterized in that, in the first aspect, the contour image data includes image data in which a contour line is extracted using multi-value information of the image data of the macroscopic tumor volume.

[0020] A radiation therapy support apparatus according to a sixth aspect of the present invention is the apparatus of the first aspect, further comprising a composite image selection unit that distributes or switches the second magnetic resonance image data and inputs it to the image composition unit.

[0021] A radiation therapy support program according to a seventh aspect of the present invention is a radiation therapy support program used in MR image-guided real-time adaptive radiation therapy, and causes a computer to execute a magnetic resonance image acquisition function that acquires magnetic resonance image data of a region including a planned target volume to be irradiated with a therapeutic radiation beam, and an image synthesis function that synthesizes predetermined contour image data with the magnetic resonance image data acquired by the magnetic resonance image acquisition function, wherein the magnetic resonance image acquisition function acquires first magnetic resonance image data which is a magnetic resonance image when the therapeutic radiation beam is being irradiated, and second magnetic resonance image data which is a magnetic resonance image when the therapeutic radiation beam is not being irradiated, and the image synthesis function synthesizes the contour image data including image data of a macroscopic tumor volume contour and image data of the planned target volume contour with the second magnetic resonance image data.

[0022] a radiation therapy system for use in MR image-guided real-time adaptive radiation therapy, the radiation therapy system comprising: a treatment planning unit that prepares an irradiation plan including a planned target volume to be irradiated with a therapeutic radiation beam; an irradiation unit that irradiates the therapeutic radiation beam based on the irradiation plan prepared by the treatment planning unit; a magnetic resonance image acquisition unit that acquires magnetic resonance image data of a region including the planned target volume to be irradiated with the therapeutic radiation beam by the irradiation unit; and an image synthesis unit that synthesizes predetermined contour image data with the magnetic resonance image data acquired by the magnetic resonance image acquisition unit, wherein the magnetic resonance image acquisition unit acquires first magnetic resonance image data which is a magnetic resonance image obtained when the therapeutic radiation beam is being irradiated and second magnetic resonance image data which is a magnetic resonance image obtained when the therapeutic radiation beam is not being irradiated, and the image synthesis unit synthesizes the contour image data including image data of a contour of a macroscopic tumor volume and image data of the contour of the planned target volume with the second magnetic resonance image data.

[0023] According to the present invention having the above-described configuration, the image synthesis unit synthesizes contour image data, including image data of the contour of the macroscopic tumor volume and image data of the contour of the planned target volume, with the second magnetic resonance image data. This makes it possible to obtain an image in which spatial resolution (including contrast resolution) is prioritized. This allows real-time monitoring during irradiation of the therapeutic radiation beam to ensure that a tumor moving due to breathing, cardiac movement, intestinal peristalsis, etc. remains within the planned target volume of the therapeutic radiation beam.

[0024] FIG. 1 is a diagram showing an example of a radiation therapy support device. FIG. 2 is a diagram showing an example of a radiation therapy system according to the first embodiment. FIG. 3 is a diagram showing an example of a radiation therapy system according to the second embodiment. FIG. 4 is a diagram showing an example of a radiation therapy system according to the third embodiment. FIG. 5 is a diagram showing an example of a radiation therapy system according to the fourth embodiment. FIGS. 6(a) and 6(b) are diagrams showing a tumor moving due to respiratory movement during deep exhalation. FIGS. 7(a) to 7(e) are diagrams showing organs in which a tumor is present, organs at risk, and planned target volumes. FIG. 8 is a flowchart showing an example of the operation of a radiation therapy support program.

[0025] A radiation therapy support device, a radiation therapy support program, and a radiation therapy system to which the present invention is applied will be described in detail below with reference to the drawings.

[0026] FIG. 1 illustrates an example of a radiation therapy support device 100. The radiation therapy support device 100 is a device used for MR image-guided real-time adaptive radiation therapy. The radiation therapy support device 100 includes a magnetic resonance image acquisition unit 46 that acquires magnetic resonance image data of a region including at least one of a planned target volume and an area near the planned target volume to be irradiated with a therapeutic radiation beam, and an image synthesis unit 42 that synthesizes contour image data with the magnetic resonance image data. The magnetic resonance image data can be obtained by imaging a patient using an MR device. For example, in the case of a liver cancer patient, magnetic resonance image data is generated by imaging a region including a liver tumor. The radiation therapy support device 100 may include, for example, a contour image generation unit 41 that generates contour image data, or may include, for example, a composite image display unit 44. The magnetic resonance image data acquired by the magnetic resonance image acquisition unit 46 and the contour image data generated by the contour image generation unit 41 from the contour image source data are input to the image synthesis unit 42. The contour image source data is generated using, for example, a known treatment planning device. The image synthesis unit 42 may acquire contour image data generated using, for example, a known treatment planning device, and the method for generating and acquiring the contour image data may be set arbitrarily depending on the application. The contour image data includes contour images of the macroscopic tumor volume, clinical target volume, planned target volume, organ volumes near the target, organ-at-risk volumes, or planned organ-at-risk volumes.

[0027] The magnetic resonance image acquisition unit 46 acquires first magnetic resonance image data, which is a magnetic resonance image when the therapeutic radiation beam is being irradiated, and second magnetic resonance image data, which is a magnetic resonance image when the therapeutic radiation beam is not being irradiated. The magnetic resonance image data acquired by the magnetic resonance image acquisition unit 46 are generated using, for example, a known MR linac system.

[0028] The image synthesis unit 42 synthesizes contour image data, including image data of the contour of the macroscopic tumor volume and image data of the contour of the planning target volume, with the second magnetic resonance image data. The image data obtained by synthesizing the contour image data, including the image data of the contour of the macroscopic tumor volume and the image data of the contour of the planning target volume, with the second magnetic resonance image data is hereinafter referred to as contour-synthesized image data. Note that a known image synthesis technique can be used as a method for synthesizing each image data.

[0029] The contour composite image data composited by the image composite unit 42 is displayed on a composite image display unit 44. The composite image display unit 44 is, for example, a display of a notebook personal computer.

[0030] The magnetic resonance image data acquired from the MR device is still image data or cine image (moving image) data.

[0031] Next, the operation of the radiation therapy support device 100 shown in FIG. 1 will be described.

[0032] An MR linac, which combines an MR device with a radiation therapy device, is characterized by its ability to acquire magnetic resonance image data during irradiation of a therapeutic radiation beam. Magnetic resonance image data is image data captured by, for example, an MR device mounted on the MR linac. The MR linac can acquire magnetic resonance image data both when a therapeutic radiation beam is being irradiated and when a therapeutic radiation beam is not being irradiated.

[0033] During irradiation of a therapeutic radiation beam, if the tumor position significantly shifts from the planned target volume to be irradiated with the therapeutic radiation beam, it is necessary to quickly stop the irradiation of the therapeutic radiation beam. For this reason, imaging using a high-speed imaging sequence that prioritizes temporal resolution is used. It is known that the pixel intensity of magnetic resonance image data acquired using the high-speed imaging sequence B-TFE is proportional to the ratio of the transverse relaxation time to the longitudinal relaxation time. However, for example, the ratio of the relaxation times of a liver tumor and normal liver tissue is almost the same. Therefore, it is often difficult to obtain a contrast between the liver tumor and normal liver tissue. Therefore, it is difficult to monitor the position of a tumor, such as a liver tumor, which moves due to respiration, in real time during irradiation with a therapeutic radiation beam.

[0034] In contrast, the radiation therapy support device 100 can display first magnetic resonance image data that prioritizes temporal resolution during irradiation of a therapeutic radiation beam, while displaying contour composite image data on the composite image display unit 44, which is obtained by combining contour image data with second magnetic resonance image data that prioritizes spatial resolution and is captured when no irradiation is being performed.

[0035] The B-TFE high-speed imaging sequence used for the first magnetic resonance image data can display approximately five images per second, allowing for near-real-time tumor movement monitoring, but has the problem of insufficient tumor contrast. On the other hand, high-speed imaging sequences, such as a T1-weighted high-speed imaging sequence or a T2-weighted high-speed imaging sequence used for the second magnetic resonance image data, can display approximately one to three images per second, and while they have a slower display speed, they have the advantage of improved tumor contrast. When the therapeutic radiation beam is not being irradiated, the second magnetic resonance image data can be acquired with a priority on spatial resolution. Therefore, when irradiation is not being performed, the second magnetic resonance image data with a priority on spatial resolution can be input to the magnetic resonance image acquisition unit 46. The second magnetic resonance image data with a priority on spatial resolution is, for example, a two-dimensional T1-weighted cine image or a two-dimensional T2-weighted cine image.

[0036] The original contour image data is image data including image data of the macroscopic tumor volume and image data of the planning target volume. When the original contour image data is input, the contour image generator 41 generates contour image data including image data of the contour of the macroscopic tumor volume and image data of the contour of the planning target volume. Note that the contour image generator 41 can generate contour image data including image data of the contour of the macroscopic tumor volume and image data of the contour of the planning target volume using known technology.

[0037] The image synthesis unit 42 synthesizes the second magnetic resonance image data acquired by the magnetic resonance image acquisition unit 46 with the preset contour image data generated by the contour image generation unit 41. With this configuration, contour synthesis image data can be acquired by synthesizing an image in which the tumor is visible, with priority given to spatial resolution, and an image in which the contour image data is superimposed, and the synthesized image can be displayed on the synthesized image display unit 44.

[0038] In this way, the radiation therapy support device 100 can acquire second magnetic resonance image data with a priority on spatial resolution and composite contour image data onto the second magnetic resonance image data. Therefore, contour composite image data can be obtained by compositely combining contour image data with the second magnetic resonance image data. Furthermore, for example, by displaying the acquired contour composite image data on the composite image display unit 44, the composite image display unit 44 can be checked during irradiation of the therapeutic radiation beam. This allows real-time monitoring during irradiation of the therapeutic radiation beam to ensure that a tumor moving due to respiration, cardiac movement, intestinal peristalsis, etc. remains within the planned target volume of the therapeutic radiation beam. During irradiation of the therapeutic radiation beam, the contrast of a tumor obtained by a T1-weighted fast imaging sequence or a T2-weighted fast imaging sequence depends on the tumor. Therefore, it is possible to alternately display images obtained by both sequences and select the sequence that provides better contrast. Note that during free breathing or suppressed breathing due to abdominal compression, the tumor undergoes respiratory movement, so the tumor contour is within the respiratory-movement range, and the planned target volume is the volume obtained by adding an irradiation margin (e.g., 3 mm to 5 mm) to this tumor contour. In contrast, when irradiating under breath-holding, the tumor does not move due to respiration, so the tumor contour is extracted without moving. In this case, the planning target volume can be defined by adding an irradiation margin to the contour of the tumor that does not move due to respiration.

[0039] Here, the second magnetic resonance image data may have a longer update time than the first magnetic resonance image data. In this case, contrast is improved, making the target visible to the naked eye or detectable by image analysis. This improves the accuracy of tumor monitoring during irradiation with the therapeutic radiation beam. For example, the first magnetic resonance image data is a cine image captured using B-TFE, and the second magnetic resonance image data is a two-dimensional T1-weighted cine image.

[0040] 2 is a diagram showing an example of a radiation therapy system 1 according to the first embodiment. The radiation therapy system 1 includes an MR linac system 2 and a treatment planning device 3 connected via a network. Magnetic resonance image data captured by an MR device mounted in the MR linac system 2 is output from the magnetic resonance image generation unit 22 via a video output I / F 221 and input to an image synthesis unit 42. Original contour image data output by the treatment planning device 3 is input to the contour image generation unit 41. The output of the contour image generation unit 41 is input to the image synthesis unit 42. Synthesized contour image data output from the image synthesis unit 42 is input to a synthetic image display unit 44.

[0041] The MR linac system 2 is a system that combines an MR device and a linac. The MR linac system 2 includes a magnetic resonance image generation unit 22 and a radiation irradiation unit 21. The magnetic resonance image data generated by the magnetic resonance image generation unit 22 is output as a signal to the outside of the MR linac system 2 via a video output I / F 221. The MR linac system 2 also includes a network I / F 27, a storage unit 24, a data processing unit 251, an operation unit 26, a display unit 23, and a video input I / F 231.

[0042] The radiation irradiation unit 21 is, for example, a linear accelerator.

[0043] The magnetic resonance image generating unit 22 is an MR device that generates magnetic resonance image data of a region including a planned target volume to be irradiated with a therapeutic radiation beam.

[0044] The video output I / F 221 is an interface that outputs image data generated by the magnetic resonance image generating unit 22 .

[0045] The network I / F 27 is an interface for connecting to an external device via a wired LAN or a wireless LAN.

[0046] The storage unit 24 is a known storage device that stores magnetic resonance image data, etc. For example, it may be a volatile storage device such as a dynamic random access memory (DRAM), or a non-volatile storage device such as a flash memory.

[0047] The data processing unit 251 is an electronic component that performs data processing using, for example, a microcontroller unit (microcontroller unit). It may be a general-purpose processor such as a CPU (Central Processing Unit), or a dedicated processor such as an FPGA (Field Programmable Gate Array).

[0048] The operation unit 26 is a device having an input device such as an operation button or a touch sensor.

[0049] The display unit 23 is a display device that displays the state of the MR linac system 2 and the images captured by the magnetic resonance image generating unit 22 .

[0050] The video input I / F 231 is an interface that displays input image data on the display unit 23 .

[0051] The image signal that transfers the image data is a digital signal that complies with a video standard such as HDMI (registered trademark) (High-Definition Multimedia Interface) or DVI (Digital Visual Interface).

[0052] Here, the connection from the treatment planning device 3 to the contour image generating unit 41 may be a connection based on a video standard such as HDMI (registered trademark), or a connection based on a network communication standard such as Ethernet. In this way, since the transfer of image data can be replaced with a transfer based on a communication standard such as LAN, the connection for transferring image data may be a connection based on a communication standard such as LAN.

[0053] The image synthesis unit 42 may include a magnetic resonance image acquisition unit 46 that acquires magnetic resonance image data from the video output I / F 221. The image synthesis unit 42 may perform synthesis using hardware such as an FPGA or an ASIC (Application Specific Integrated Circuit), or may perform synthesis using software using a microcontroller.

[0054] The composite image display unit 44 displays the input image. The composite image display unit 44 may be a display device that displays an image by emitting light from its screen, or may be configured to display the image on the screen of a tablet terminal or smartphone via communication.

[0055] 3 is a diagram showing an example of a radiation therapy system 1 according to the second embodiment. In the second embodiment, the same components and members as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted.

[0056] The radiation therapy system 1 according to the second embodiment includes a magnetic resonance image storage unit 43. The magnetic resonance image storage unit 43 stores second magnetic resonance image data in which spatial resolution is prioritized.

[0057] The magnetic resonance image data generated by the magnetic resonance image generating unit 22 is input to the magnetic resonance image storage unit 43 via the video output I / F 221. The output of the magnetic resonance image storage unit 43 is input to the image synthesis unit .

[0058] During irradiation of the therapeutic radiation beam, the magnetic resonance image generating unit 22 outputs the first magnetic resonance image data, and the second magnetic resonance image data, which is acquired when irradiation is not being performed and prioritizes spatial resolution, can be stored in the magnetic resonance image storage unit 43. With this configuration, contour composite image data, which is obtained by combining the second magnetic resonance image data stored in the magnetic resonance image storage unit 43 with contour image data, can be displayed on the composite image display unit 44.

[0059] The magnetic resonance image storage unit 43 stores the magnetic resonance image data generated by the magnetic resonance image generation unit 22. The magnetic resonance image storage unit 43 may be a volatile storage device such as a DRAM, or a non-volatile storage device such as a flash memory.

[0060] Alternatively, the magnetic resonance image storage unit 43, the contour image generation unit 41, the image synthesis unit 42, and the composite image display unit 44 may be configured using a notebook personal computer or a desktop personal computer. When configured using a notebook personal computer, the magnetic resonance image storage unit 43 is the DRAM of the personal computer, data processing by the contour image generation unit 41 and the image synthesis unit 42 is data processing by the CPU, and the composite image display unit 44 is the display of the notebook personal computer.

[0061] 4 is a diagram showing an example of a radiation therapy system 1 according to the third embodiment. In the third embodiment, the same components and members as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted.

[0062] The third embodiment differs from the first embodiment in that it includes a selection unit 452 .

[0063] The magnetic resonance image data output by the video output I / F 221 is input to a selection unit 452. One output of the selection unit 452 is input to the video input I / F 231 of the MR linac system 2, and the other output is input to the image synthesis unit 42.

[0064] The selector 452 is a composite image selector that distributes or switches the second magnetic resonance image data and inputs it to the image composition unit. The selector 452 selectively outputs the input video signal. The selector 452 outputs the video signal to, for example, either the video input I / F 231 or the image composition unit 42 of the MR linac system 2. The selector 452 can output the video signal to the video input I / F 231 when the input video signal is the first magnetic resonance image data, and can output the video signal to the image composition unit 42 when the input video signal is the second magnetic resonance image data.

[0065] The selector 452 may have a built-in image storage device. In this case, the input image signal can be passed through to one selected output, and a video signal of an image previously stored in the image storage device can be output to the other selected output. Alternatively, the selector 452 may be configured to pass through the input image signal and distribute it to both outputs, and the image synthesis unit 42 may synthesize the second magnetic resonance image data.

[0066] By providing a selection unit 452 that distributes or switches the magnetic resonance image data acquired by the magnetic resonance image acquisition unit 46 and inputs it to the image synthesis unit 42, the magnetic resonance image data generated by the magnetic resonance image generation unit 22 can be returned to the video input I / F 231. This improves the efficiency of tumor monitoring during irradiation with therapeutic radiation beams.

[0067] 5 is a diagram showing an example of a radiation therapy system 1 according to the fourth embodiment. In the fourth embodiment, the same components and members as those in the third embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0068] The radiation therapy system 1 according to the fourth embodiment includes an MR linac system 5 with built-in image synthesis.

[0069] The image synthesis built-in data processing unit 252 includes a magnetic resonance image acquisition unit 46, a contour image generation unit 41, and an image synthesis unit 42. The image synthesis built-in data processing unit 252 also includes a contour image generation unit 41 that generates original contour image data. The magnetic resonance image data acquired by the magnetic resonance image acquisition unit 46 and the contour image data generated by the contour image generation unit 41 are input to the image synthesis unit 42.

[0070] The magnetic resonance image acquisition unit 46 of the data processing unit 252 with built-in image synthesis acquires the magnetic resonance image data generated by the magnetic resonance image generation unit 22. With this configuration, contour-synthesized image data, in which the contour of the tumor and the contour of the planned target volume are synthesized, can be displayed on the display unit 23 inside the MR linac system 5 with built-in image synthesis. The display unit 23 may display the contour-synthesized image data in picture-in-picture format in addition to the first magnetic resonance image data and the second magnetic resonance image data displayed in a known MR linac system.

[0071] An organ at risk is a normal organ located around an organ where a tumor has developed. For example, in the case of lung cancer, the organ at risk is a normal organ adjacent to the lung, such as the trachea or heart. Because the risk of a therapeutic radiation beam hitting an organ at risk poses a risk of complications, real-time monitoring is required to prevent the therapeutic radiation beam from hitting the organ at risk. The contour image generator 41 generates image data of the contours of the organ at risk from original contour image data including the organ at risk. Therefore, contour-synthesized image data can be obtained by synthesizing the contour image data including the image data of the organ at risk with the magnetic resonance image data using the image synthesizer 42. This allows real-time monitoring to ensure that the organ at risk is not within the planned target volume during irradiation with the therapeutic radiation beam.

[0072] The dose distribution is the distribution of doses planned by a treatment planning system. The contour image generator 41 generates image data of the dose distribution from original contour image data including the dose distribution. Therefore, contour-synthesized image data can be obtained by synthesizing the contour image data including image data of the dose distribution contour with the magnetic resonance image data in the image synthesizer 42. This allows the relative positional relationship between the dose distribution and the planned target volume to be monitored in real time during irradiation of the therapeutic radiation beam.

[0073] The magnetic resonance image acquisition unit 46 alternately switches between acquiring the first magnetic resonance image and acquiring the second magnetic resonance image, thereby updating the second magnetic resonance image data and synthesizing an image that reflects the latest tumor position. This improves the accuracy of tumor monitoring during therapeutic radiation beam irradiation. Furthermore, if imaging using B-TFE, a high-speed imaging sequence of the MR device, is not performed during therapeutic radiation beam irradiation, slow but high-contrast T2 cine images can be acquired even during therapeutic radiation beam irradiation. In this case, the magnetic resonance image acquisition unit 46 may alternate between image data obtained using the high-speed imaging sequence and slow but high-contrast T2 cine image data.

[0074] The image synthesis unit 42 synthesizes image data in which contour lines are extracted using multi-valued information of macroscopic tumor volume image data with the second magnetic resonance image data generated by the magnetic resonance image generation unit 22, thereby improving the accuracy of the tumor contour image data and improving the accuracy of tumor monitoring during therapeutic radiation beam irradiation. Here, multi-valued information includes grayscale images and color images as opposed to binary information such as black-and-white image data. When extracting contour lines from image data, well-known binarization techniques using Laplace filters, Laplace-Gauss filters, etc. are often used. However, binarization may extract non-contour parts, such as image noise, or may fail to extract necessary contour parts. Therefore, the accuracy of tumor contour image data can be improved by using multi-valued information including multiple gradations between 0 and 1, rather than just binary values ​​such as 0 and 1. Furthermore, the resolution of image data can be increased by using super-resolution technology that predicts or restores high-frequency components of low-resolution images.

[0075] Next, the operation of the radiation therapy system 1 according to the first embodiment will be described with reference to FIG.

[0076] The image synthesis unit 42 synthesizes the second magnetic resonance image data generated by the magnetic resonance image generation unit 22 of the MR linac system 2 with contour image data output via the video output I / F 221. The synthesized contour synthesized image data is displayed on the synthesized image display unit 44. Here, during irradiation of the therapeutic radiation beam, the display unit 23 of the MR linac system 2 displays the first magnetic resonance image data or the second magnetic resonance image data generated by the magnetic resonance image generation unit 22, while the synthesized image display unit 44 displays contour synthesized image data obtained by synthesizing the contour image data with the second magnetic resonance image data.

[0077] During irradiation of the therapeutic radiation beam, the first magnetic resonance image data, which prioritizes temporal resolution, can be displayed on the display unit 23, while contour composite image data, which is obtained by combining preset contour image data with the second magnetic resonance image data, which prioritizes spatial resolution, can be displayed on the composite image display unit 44. Therefore, it is possible to monitor in real time during irradiation of the therapeutic radiation beam whether a tumor, which moves due to breathing, cardiac movement, or the like, remains within the planned target volume.

[0078] Next, the operation of the radiation therapy system 1 according to the second embodiment will be described with reference to FIG.

[0079] The second magnetic resonance image generated by the magnetic resonance image generating unit 22 of the MR linac system 2 is input to and stored in the magnetic resonance image storage unit 43 via the video output I / F 221. With this configuration, it is possible to read out data of the second magnetic resonance image during irradiation of the therapeutic radiation beam. As a result, it is possible to display on the composite image display unit 44 contour composite image data in which an image in which the tumor is visible, with priority given to spatial resolution, is superimposed on the contour image data during irradiation of the therapeutic radiation beam.

[0080] Next, the operation of the radiation therapy system 1 according to the third embodiment will be described with reference to FIG.

[0081] The second magnetic resonance image generated by the magnetic resonance image generation unit 22 of the MR linac system 2 is input to the selection unit 452 via the video output I / F 221. The first magnetic resonance image and the second magnetic resonance image are output from the magnetic resonance image generation unit 22, and the selection unit 452 can select the magnetic resonance image to be input to the image synthesis unit 42. Here, the selection unit 452 may have an internal storage device, and in that case, the selection unit 452 outputs the magnetic resonance image data stored in the internal storage device.

[0082] Next, the operation of the radiation therapy system 1 according to the fourth embodiment will be described with reference to FIG.

[0083] The magnetic resonance image acquisition unit 46 of the data processing unit 252 with built-in image synthesis acquires the second magnetic resonance image data generated by the magnetic resonance image generation unit 22. The acquired second magnetic resonance image data and the contour image data generated by the contour image generation unit 41 are synthesized by the image synthesis unit 42. The synthesized contour synthesis image data is displayed on the display unit 23. In this way, the MR linac system 5 with built-in image synthesis may be configured such that the image synthesis unit 42 is built into the data processing unit 252 with built-in image synthesis.

[0084] The radiation therapy support program is explained below.

[0085] FIG. 8 is a flowchart showing an example of the operation of the radiation therapy support program. The radiation therapy support program causes a computer to execute a magnetic resonance image generation function for generating magnetic resonance image data of a region including a planned target volume to be irradiated with a therapeutic radiation beam and an image synthesis function for synthesizing contour image data and magnetic resonance image data. The computer may be a desktop PC (Personal Computer), a notebook PC, a smartphone, a tablet terminal, or a microcomputer in an embedded system. The first step S110 marks the beginning of a loop, and the fourth step S140 marks the end of the loop. The processes between the first step S110 and the fourth step S140 are repeated while the automatic update mode is TRUE. The second step S120 is a process performed by a magnetic resonance image acquisition function for acquiring magnetic resonance image data of a region including a planned target volume to be irradiated with a therapeutic radiation beam. Here, the magnetic resonance image acquisition function acquires first magnetic resonance image data, which is a magnetic resonance image when the therapeutic radiation beam is being irradiated, and second magnetic resonance image data, which is a magnetic resonance image when the therapeutic radiation beam is not being irradiated. The third step S130 is a process performed by the image synthesis function. The image synthesis function synthesizes the second magnetic resonance image data with contour image data including image data of the contour of the macroscopic tumor volume and image data of the contour of the planning target volume, and outputs contour synthesis image data. When the automatic update mode is no longer TRUE, the process exits the loop of the fourth step S140 and ends.

[0086] FIG. 6 shows a respiratory-moving tumor during deep exhalation.

[0087] The planned target volume 61 is a volume to be irradiated with the therapeutic radiation beam calculated by the treatment planning device 3. A tumor 62A before deep exhalation moves to the position of a tumor 62B when deep exhalation is performed. In the radiation therapy system 1, an irradiation plan is created by the treatment planning unit so that a predetermined radiation dose is irradiated to the tumor and the radiation dose irradiated to surrounding normal tissue is minimized. The treatment planning unit is, for example, a known treatment planning device.

[0088] FIG. 7 is a diagram showing tumor-bearing organs, organs at risk, and planning target volumes.

[0089] FIG. 7( a) is an example of a high-speed imaging sequence image in which temporal resolution is prioritized due to irradiation with a therapeutic radiation beam. Due to low contrast, the tumor position (see tumor 71 in FIG. 7( b)) cannot be confirmed. FIG. 7( b) is a high-contrast 2D T1-weighted cine image and a 2D T2-weighted cine image obtained without irradiation with a therapeutic radiation beam, in which spatial resolution is prioritized. The positions of a tumor 71 and an organ at risk 72 in an organ 74 in which the tumor is present are clearly confirmed. The tumor 71 indicates the macroscopic tumor volume. FIG. 7( c) shows the outline 741 of the organ in which the tumor is present, the outline 711 of the tumor, the outline 721 of the organ at risk, and the outline 731 of the planned target volume. FIG. 7( d) is a composite image of the outlines of FIGS. 7( b) and 7( c). In FIG. 7( d), the tumor 71 and the outline 711 of the tumor, and the outlines 721 of the organ at risk are in the same position. Figure 7(e) is a diagram showing movement associated with breathing and cardiac movement. In Figure 7(e), it can be seen that the tumor 71 and the tumor contour 711, and the organ-at-risk 72 and the organ-at-risk contour 721 are in different positions. Furthermore, looking at Figures 7(d) and 7(e) with a focus on the planning target volume 731, it can be seen that in Figure 7(e), the organ-at-risk 72 moves into the planning target volume 731 due to breathing and cardiac movement. If such a situation is confirmed, it becomes necessary to make a decision, such as to interrupt irradiation of the therapeutic radiation beam.

[0090] In the embodiments of the present invention, examples of radiation therapy using X-ray beams and electron beams have been presented, but the present invention can also be applied to gamma ray therapy, proton therapy, and heavy particle therapy.

[0091] Although an embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. Such novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its modifications are included within the scope and spirit of the invention, and are also included in the inventions described in the claims and their equivalents.

[0092] REFERENCE SIGNS LIST 1 Radiation therapy system 2 MR linac system 21 Radiation irradiation unit 22 Magnetic resonance image generation unit 221 Video output I / F 23 Display unit 231 Video input I / F 24 Storage unit 251 Data processing unit 252 Data processing unit with built-in image synthesis 26 Operation unit 27 Network I / F 3 Treatment planning device 41 Contour image generation unit 42 Image synthesis unit 43 Magnetic resonance image storage unit 44 Synthesized image display unit 452 Selection unit 46 Magnetic resonance image acquisition unit 5 MR linac system with built-in image synthesis 61 Planning target volume 62A Tumor (before deep exhalation) 62B Tumor (moving due to respiration when deep exhalation is performed) 71 Tumor 711 Tumor contour 72 Organ at risk 721 Contour of organ at risk 731 Contour of planning target volume 74 Organ in which tumor occurs 741 Outline of the organ where the tumor is occurring 100 Radiation therapy support device

Claims

1. A radiation therapy support device used in MR image-guided real-time adaptive radiation therapy, comprising: a magnetic resonance image acquisition unit that acquires magnetic resonance image data of a region including a planned target volume to be irradiated with a therapeutic radiation beam; and an image synthesis unit that synthesizes preset contour image data with the magnetic resonance image data acquired by the magnetic resonance image acquisition unit, wherein the magnetic resonance image acquisition unit acquires first magnetic resonance image data which is a magnetic resonance image when the therapeutic radiation beam is being irradiated, and second magnetic resonance image data which is a magnetic resonance image when the therapeutic radiation beam is not being irradiated, and the image synthesis unit synthesizes the contour image data including image data of the contour of a macroscopic tumor volume and image data of the contour of the planned target volume with the second magnetic resonance image data.

2. A radiation therapy support device according to claim 1, characterized in that the second magnetic resonance image data has a longer update time than the first magnetic resonance image data.

3. The radiation therapy support device according to claim 1, characterized in that the contour image data includes image data of the contour of an organ at risk or image data of the contour of a dose distribution.

4. A radiation therapy support device as described in claim 1, characterized in that the magnetic resonance image acquisition unit alternately switches between acquisition of the first magnetic resonance image data and acquisition of the second magnetic resonance image data.

5. A radiation therapy support device according to claim 1, characterized in that the contour image data includes image data in which a contour line is extracted using multi-value information of the image data of the macroscopic tumor volume.

6. The radiation therapy support device according to claim 1, further comprising a composite image selection unit which distributes or switches the second magnetic resonance image data and inputs it to the image synthesis unit.

7. A radiation therapy support program used in MR image-guided real-time adaptive radiation therapy, comprising: a computer that executes a magnetic resonance image acquisition function for acquiring magnetic resonance image data of an area including a planned target volume to be irradiated with a therapeutic radiation beam; and an image synthesis function for synthesizing predetermined contour image data with the magnetic resonance image data acquired by the magnetic resonance image acquisition function; wherein the magnetic resonance image acquisition function acquires first magnetic resonance image data which is a magnetic resonance image when the therapeutic radiation beam is being irradiated, and second magnetic resonance image data which is a magnetic resonance image when the therapeutic radiation beam is not being irradiated; and the image synthesis function synthesizes the contour image data including image data of the contour of a macroscopic tumor volume and image data of the contour of the planned target volume with the second magnetic resonance image data.

8. A radiation therapy system used in MR image-guided real-time adaptive radiation therapy, comprising: a treatment planning unit which prepares an irradiation plan including a planned target volume to be irradiated with a therapeutic radiation beam; an irradiation unit which irradiates the therapeutic radiation beam based on the irradiation plan prepared by the treatment planning unit; a magnetic resonance image acquisition unit which acquires magnetic resonance image data of an area including the planned target volume to be irradiated with the therapeutic radiation beam by the irradiation unit; and an image synthesis unit which synthesizes predetermined contour image data with the magnetic resonance image data acquired by the magnetic resonance image acquisition unit, wherein the magnetic resonance image acquisition unit acquires first magnetic resonance image data which is a magnetic resonance image when the therapeutic radiation beam is being irradiated, and second magnetic resonance image data which is a magnetic resonance image when the therapeutic radiation beam is not being irradiated, and the image synthesis unit synthesizes the contour image data including image data of the contour of a macroscopic tumor volume and image data of the contour of the planned target volume with the second magnetic resonance image data.

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