WO2024257712A1 - Radiation treatment assistance device, radiation treatment assistance program, and radiation treatment system - Google Patents

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

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

Radiation therapy is one of the "three pillars of cancer treatment" and plays an important role in cancer treatment. In radiation therapy, it is important to understand the location of the targeted tumor.

MRI (Magnetic Resonance Imaging) images taken with an MR (Magnetic Resonance) device have better contrast resolution between normal tissue and tumors in soft tissue than images taken with an 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.

In recent years, MR linacs, which combine MR devices and linacs, have been put to clinical use. 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 which the therapeutic radiation beam is irradiated.

The spatial extent of the 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. Planning target volume is the target volume that is determined taking into account the uncertainties of radiation therapy.

MR image-guided immediate adaptive radiation therapy is a type of radiation therapy in which, with the patient positioned on the treatment bed, three-dimensional MR images are acquired on the day of treatment, and based on the images, contours are drawn, a new treatment plan is created, verified, and radiation is administered. In MR image-guided immediate adaptive radiation therapy using an MR linac, in order to confirm that radiation is being administered according to the treatment plan created immediately before treatment, it is important to directly observe the tumor being irradiated with the therapeutic radiation beam using MR images and to appropriately control the therapeutic radiation beam. Specifically, the macroscopic tumor volume is grasped using MR images, and the therapeutic radiation beam of the linac is controlled based on the planned target volume calculated using a treatment planning device.

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

Patent document 2 discloses the configuration of an MR device combined with a linear accelerator. The system discloses a system for more quickly acquiring imaging slices by comparing information indicating a portion of a target trajectory that is rapidly acquired from one or more imaging slices with information acquired from a previously acquired volume reference image.

Special Publication No. 2020-523075 Special Publication No. 2022-544780

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.

The tumor, which is the target of radiation irradiation, moves with breathing, heart movement, intestinal peristalsis, etc. This can result in the therapeutic radiation beam being significantly displaced from the planned target volume.

If the tumor position significantly shifts from the planned target volume into which the therapeutic radiation beam is to be irradiated, it is necessary to quickly stop the irradiation of the therapeutic radiation beam. This action prevents damage to areas other than the targeted tumor that would otherwise be caused by the irradiation of the therapeutic radiation beam. For this reason, it is important to check the tumor position in real time while the therapeutic radiation beam is being irradiated.

For this reason, in the MR linac, a high-speed imaging sequence such as B-TFE that prioritizes time resolution is used during irradiation of the therapeutic radiation beam. However, high-speed imaging sequences have low contrast because the data update time is shortened. For this reason, there is a problem with high-speed imaging sequences in that it is not possible to monitor in real time during irradiation of the therapeutic radiation beam whether a tumor that moves due to breathing, cardiac movement, intestinal peristalsis, etc. remains 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.

The present invention was conceived in consideration of the above-mentioned problems, and its purpose is to provide a radiation therapy support device, a radiation therapy support program, and a radiation therapy system that can monitor 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.

The radiation therapy support device according to the first 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 an area 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, 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 the macroscopic tumor volume and image data of the contour of the planned target volume with the second magnetic resonance image data.

The radiation therapy support device according to the second invention is the same as the first invention, but is characterized in that the second magnetic resonance image data has a longer update time than the first magnetic resonance image data.

The radiation therapy support device according to the third invention is the first invention, characterized in that the contour image data includes image data of the contours of risk organs or image data of the contours of dose distribution.

The radiation therapy support device according to the fourth invention is the same as the first invention, but is 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.

The radiation therapy support device according to the fifth invention is the first invention, 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.

The radiation therapy support device according to the sixth invention is the first invention, further comprising a composite image selection unit that distributes or switches the second magnetic resonance image data and inputs it to the image synthesis unit.

The radiation therapy support program according to the seventh 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 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 preset contour image data with the magnetic resonance image data acquired by the magnetic resonance image acquisition function, the magnetic resonance image acquisition function acquiring 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 the macroscopic tumor volume and image data of the contour of the planned target volume with the second magnetic resonance image data.

The radiation therapy system according to the eighth invention is a radiation therapy system used for MR image-guided real-time adaptive radiation therapy, and includes a treatment planning unit that creates 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 created by the treatment planning unit, a magnetic resonance image acquisition unit that 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 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 the macroscopic tumor volume and image data of the contour of the planned target volume with the second magnetic resonance image data.

According to the present invention having the above-mentioned 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. Therefore, an image can be obtained in which spatial resolution (including contrast resolution) is prioritized. This makes it possible to monitor in real time during irradiation of the therapeutic radiation beam whether a tumor that moves due to breathing, cardiac movement, intestinal peristalsis, etc. remains within the planned target volume of the therapeutic radiation beam.

FIG. 1 is a diagram illustrating an example of a radiation therapy support apparatus. FIG. 2 is a diagram illustrating an example of a radiation therapy system according to the first embodiment. FIG. 3 is a diagram illustrating an example of a radiation therapy system according to the second embodiment. FIG. 4 is a diagram illustrating an example of a radiation therapy system according to the third embodiment. FIG. 5 is a diagram illustrating an example of a radiation therapy system according to the fourth embodiment. 6(a) and 6(b) show respiratory-moving tumors during deep expiration. 7(a)-7(e) show diagrams depicting tumor-bearing organs, organs at risk and planning target volumes. FIG. 8 is a flowchart showing an example of the operation of the radiation therapy support program.

Below, the radiation therapy support device, radiation therapy support program, and radiation therapy system to which the present invention is applied will be described in detail with reference to the drawings.

1 is a diagram showing 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 an area including at least one of a planned target volume to be irradiated with a therapeutic radiation beam or an area near the planned target volume, 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 an area 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 synthetic 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 original data are input to the image synthesis unit 42. The contour image original data is generated using, for example, a known treatment planning device. The image synthesis unit 42 may also acquire contour image data generated using, for example, a known treatment planning device, and the method of generating and acquiring the contour image data can 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 volume near the target, organ at risk volume, or planned organ at risk volume.

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 is generated, for example, using a known MR linac system.

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 planned target volume, which are preset with respect to the second magnetic resonance image data. Hereinafter, image data obtained by synthesizing the 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 respect to the second magnetic resonance image data will be referred to as contour synthesis image data. Note that a publicly known image synthesis technique can be used as a method for synthesizing each image data.

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

The magnetic resonance image data obtained from the MR device is still image data or cine image (moving image) data.

Next, we will explain the operation of the radiation therapy support device 100 in Figure 1.

An MR linac, which combines an MR device with a radiation therapy device, has the advantage of being able to acquire magnetic resonance image data while a therapeutic radiation beam is being irradiated. Magnetic resonance image data is image data captured, for example, by an MR device mounted on the MR linac. The MR linac can acquire magnetic resonance image data not only when a therapeutic radiation beam is not being irradiated, but also when a therapeutic radiation beam is being irradiated.

Here, during irradiation of the therapeutic radiation beam, if the position of the tumor significantly shifts from the planned target volume to which the therapeutic radiation beam is irradiated, 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 time resolution is used. It is known that the pixel intensity of magnetic resonance image data imaged using the high-speed imaging sequence B-TFE is proportional to the ratio of the transverse relaxation time to the longitudinal relaxation time, but for example, the ratio of relaxation times is almost the same for liver tumors and normal liver tissue. For this reason, it is often the case that there is no contrast between liver tumors and normal liver tissue. Therefore, it is difficult to monitor tumors, such as liver tumors that move due to respiration, in real time during irradiation of the therapeutic radiation beam.

In response to this, the radiation therapy support device 100 can display first magnetic resonance image data that prioritizes time resolution during irradiation of a therapeutic radiation beam, while displaying on the composite image display unit 44 contour composite image data that combines contour image data with second magnetic resonance image data that prioritizes spatial resolution captured when irradiation is not occurring.

The B-TFE high-speed imaging sequence used for the first magnetic resonance image data can display about five images per second, making it possible to monitor the movement of the tumor in almost real time, but there has been a problem with insufficient contrast of the tumor. On the other hand, high-speed imaging sequences such as the T1-weighted high-speed imaging sequence or the T2-weighted high-speed imaging sequence used for the second magnetic resonance image data can display about one to three images per second, and although the display speed is inferior, it has the advantage of improving the contrast of the tumor. 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.

The original contour image data is image data including image data of the macroscopic tumor volume and image data of the planned target volume. When the original contour image data is input, the contour image generating unit 41 generates 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. Note that the contour image generating unit 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 planned target volume using known technology.

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. By configuring in this way, contour synthesis image data can be acquired that synthesizes 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 synthetic image display unit 44.

In this way, the radiation therapy support device 100 can acquire second magnetic resonance image data with a priority on spatial resolution, and synthesize contour image data with the second magnetic resonance image data. Therefore, it is possible to obtain contour synthetic image data in which contour image data is synthesized with the second magnetic resonance image data. In addition, for example, by displaying the acquired contour synthetic image data on the synthetic image display unit 44, the synthetic image display unit 44 can be checked during irradiation of the therapeutic radiation beam. This makes it possible to monitor in real time during irradiation of the therapeutic radiation beam that a tumor moving due to breathing, cardiac movement, intestinal peristalsis, etc. remains in the planned target volume of the therapeutic radiation beam. During irradiation of the therapeutic radiation beam, the contrast of the tumor by the T1-weighted fast imaging sequence or the T2-weighted fast imaging sequence depends on the tumor, so it is possible to alternately display images obtained by both sequences and select and use the sequence that gives better contrast. Note that under free breathing or suppressed breathing due to abdominal compression, the tumor moves due to respiratory movement, so the tumor contour is within the range of respiratory movement, and the volume obtained by adding an irradiation margin (for example, 3 mm to 5 mm) to this tumor contour becomes the planned target volume. In contrast, when irradiating with 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.

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 and the target can be seen with the naked eye or detected by image analysis. This improves the accuracy of tumor monitoring during irradiation of the therapeutic radiation beam. For example, the first magnetic resonance image data is a cine image captured by B-TFE, and the second magnetic resonance image data is a two-dimensional T1-weighted cine image.

FIG. 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 on the MR linac system 2 is output from the magnetic resonance image generation unit 22 via the video output I/F 221 and input to the image synthesis unit 42. The 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. The contour synthesis image data output from the image synthesis unit 42 is input to the synthesis image display unit 44.

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 generating unit 22 and a radiation irradiation unit 21. The magnetic resonance image data generated by the magnetic resonance image generating 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 memory unit 24, a data processing unit 251, an operation unit 26, a display unit 23, and a video input I/F 231.

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

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

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

The network I/F 27 is an interface that connects to external devices via a wired LAN or wireless LAN.

The storage unit 24 is a known storage device in which magnetic resonance image data and the like are stored. 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.

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

The operation unit 26 is a device that has an input device such as an operation button or a touch sensor.

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

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

The image signal that transfers the image data is, for example, a digital signal based on a video standard such as HDMI (registered trademark) (High-Definition Multimedia Interface) or DVI (Digital Visual Interface).

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), but it may also be 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.

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.

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

FIG. 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 parts as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted below.

The radiation therapy system 1 according to the second embodiment has 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.

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 42.

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 captured when irradiation is not being performed and prioritizes spatial resolution, can be stored in the magnetic resonance image storage unit 43. By configuring in this manner, it is possible to display on the composite image display unit 44 the 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 the contour image data.

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.

The magnetic resonance image storage unit 43, the contour image generation unit 41, the image synthesis unit 42, and the synthetic image display unit 44 may also 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 synthetic image display unit 44 is the display of the notebook personal computer.

FIG. 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 below.

Compared to the first embodiment, the third embodiment has a selection unit 452.

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

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

The selection unit 452 may have a built-in image storage device. In that case, the input video 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 output. The selection unit 452 may also be configured to distribute the input video signal so that it is passed through and output to both, and the image synthesis unit 42 synthesizes the second magnetic resonance image data.

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 makes it possible to improve the operability of monitoring tumors during irradiation with therapeutic radiation beams.

FIG. 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 described above are denoted by the same reference numerals, and the description thereof will be omitted below.

The radiation therapy system 1 according to the fourth embodiment is equipped with an MR linac system 5 with built-in image synthesis.

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 contour image original 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.

The magnetic resonance image acquisition unit 46 of the built-in image synthesis data processing unit 252 acquires the magnetic resonance image data generated by the magnetic resonance image generation unit 22. With this configuration, it is possible to display on the display unit 23 contour synthesis image data that synthesizes the contour of the tumor and the contour of the planned target volume inside the built-in image synthesis MR linac system 5. The display unit 23 may display the contour synthesis image data as a picture-in-picture display in addition to the first magnetic resonance image data and the second magnetic resonance image data that are displayed in a known MR linac system.

A risk organ is a normal organ that is located around an organ in which a tumor has developed. In the case of lung cancer, for example, risk organs are normal organs adjacent to the lungs, such as the trachea and heart. If a therapeutic radiation beam hits a risk organ, there is a risk of complications, etc., so real-time monitoring is required to prevent the therapeutic radiation beam from hitting the risk organ. The contour image generator 41 generates image data of the contours of the risk organ from the original contour image data that includes the risk organ. For this reason, contour-synthesized image data can be obtained by synthesizing the contour image data that includes the image data of the contours of the risk organ with the magnetic resonance image data in the image synthesizer 42. This makes it possible to monitor in real-time that the risk organ is not within the planned target volume during irradiation of the therapeutic radiation beam.

The dose distribution is the distribution of dose planned by the treatment planning device. The contour image generating unit 41 generates image data of the dose distribution from the 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 synthesis unit 42. This makes it possible to monitor the relative positional relationship between the dose distribution and the planned target volume in real time during irradiation of the therapeutic radiation beam.

The magnetic resonance image acquisition unit 46 can update the second magnetic resonance image data and synthesize an image reflecting the latest tumor position by alternately switching between acquiring the first magnetic resonance image and acquiring the second magnetic resonance image. This can improve the accuracy of tumor monitoring during irradiation of the therapeutic radiation beam. Furthermore, if imaging using B-TFE, a high-speed imaging sequence of the MR device, is not performed during irradiation of the therapeutic radiation beam, slow but high-contrast T2 cine images can be captured even during irradiation of the therapeutic radiation beam. In that case, the magnetic resonance image acquisition unit 46 may alternate between image data using the high-speed imaging sequence and slow but high-contrast T2 cine image data.

The image synthesis unit 42 synthesizes the second magnetic resonance image data generated by the magnetic resonance image generation unit 22 with image data in which the contour line is extracted using the multi-value information of the macroscopic tumor volume image data, thereby improving the accuracy of the tumor contour image data and improving the accuracy of tumor monitoring during irradiation with a therapeutic radiation beam. Here, multi-value information includes grayscale images and color images for binary information such as black and white image data. When extracting the contour line from image data, many known techniques are used for binarization using a Laplace filter or a Laplace-Gaussian filter. However, binarization may extract parts that are not actually contours, such as image noise, or may not extract the necessary contour parts. Therefore, the accuracy of the tumor contour image data can be improved by using multi-value information including multiple gradations between 0 and 1, rather than only two values such as 0 and 1. In addition, the resolution of the image data can be increased by using a super-resolution technique that predicts or restores high-frequency components of a low-resolution image.

Next, the operation of the radiation therapy system 1 according to the first embodiment will be explained using FIG. 2.

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 the 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 the contour synthesized image data in which the contour image data is synthesized with the second magnetic resonance image data.

During irradiation of the therapeutic radiation beam, the first magnetic resonance image data in which temporal resolution is prioritized is displayed on the display unit 23, while the composite image display unit 44 can display contour composite image data in which preset contour image data is composited with the second magnetic resonance image data in which spatial resolution is prioritized. Therefore, it is possible to monitor in real time during irradiation of the therapeutic radiation beam whether a tumor that moves due to breathing, cardiac movement, etc. remains within the planned target volume.

Next, the operation of the radiation therapy system 1 according to the second embodiment will be explained using FIG. 3.

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, the data of the second magnetic resonance image can be read out during irradiation of the therapeutic radiation beam. This makes it possible to display on the composite image display unit 44 contour composite image data that is a superimposition of an image in which the tumor is visible with a priority given to spatial resolution during irradiation of the therapeutic radiation beam and the contour image data.

Next, the operation of the radiation therapy system 1 according to the third embodiment will be explained using FIG. 4.

The second magnetic resonance image generated by the magnetic resonance image generating 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 generating 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, in which case the selection unit 452 outputs the magnetic resonance image data stored in the internal storage device.

Next, the operation of the radiation therapy system 1 according to the fourth embodiment will be explained using FIG. 5.

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 in such a way that the data processing unit 252 with built-in image synthesis has the image synthesis unit 42 built in.

The radiation therapy support program is explained below.

FIG. 8 is a flowchart showing an example of the operation of the radiation therapy support program. The radiation therapy support program causes the computer to execute a magnetic resonance image generation function for generating 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 contour image data and magnetic resonance image data. The computer is a desktop PC (Personal Computer), a notebook PC, a smartphone, a tablet terminal, or a microcomputer of an embedded system. The first step S110 is the start of the loop, and the fourth step S140 is the end of the loop. While the automatic update mode is TRUE, the processing between the first step S110 and the fourth step S140 is repeated. The second step S120 is processing performed by 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. 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 irradiated, and second magnetic resonance image data, which is a magnetic resonance image when the therapeutic radiation beam is not 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 loop of the fourth step S140 is exited and the process is terminated.

Figure 6 shows a tumor moving with respiration during deep expiration.

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

Figure 7 shows the organs in which the tumor is present, the organs at risk, and the planned target volume.

7(a) is an example of a high-speed imaging sequence image in which temporal resolution is prioritized due to irradiation of a therapeutic radiation beam, and the tumor position (see tumor 71 in FIG. 7(b)) cannot be confirmed due to low contrast. FIG. 7(b) is a high-contrast two-dimensional T1-weighted cine image and two-dimensional T2-weighted cine image obtained by prioritizing spatial resolution due to not irradiating a therapeutic radiation beam, and shows that the positions of tumor 71 and risk organ 72 in organ 74 in which the tumor is occurring can be clearly confirmed. Tumor 71 shows the macroscopic tumor volume. FIG. 7(c) shows the contour 741 of the organ in which the tumor is occurring, the tumor contour 711, the contour 721 of the risk organ, and the contour 731 of the planned target volume. FIG. 7(d) is contour composite image data obtained by combining FIG. 7(b) and FIG. 7(c). In FIG. 7(d), tumor 71 and tumor contour 711, and risk organ 72 and risk organ contour 721 are in the same position. FIG. 7(e) is a diagram showing movement associated with breathing and cardiac movement. In FIG. 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. Also, looking at FIG. 7(d) and FIG. 7(e) with attention to the planned target volume 731, it can be seen that in FIG. 7(e), the organ at risk 72 moves into the planned target volume 731 due to breathing and cardiac movement. If such a situation is confirmed, it becomes necessary to make a decision to interrupt irradiation of the therapeutic radiation beam, for example.

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

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 implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. This embodiment and its modifications are included within the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

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 Image synthesis built-in data processing unit 26 Operation unit 27 Network I/F
3 Treatment planning device 41 Contour image generating 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 Image synthesis built-in MR linac system 61 Planning target volume 62A Tumor (before deep exhalation) 62B Tumor (moving with respiration when deep exhalation is performed) 71 Tumor 711 Tumor contour 72 Risk organ 721 Risk organ contour 731 Planning target volume contour 74 Organ in which tumor occurs 741 Contour of organ in which tumor occurs 100 Radiation therapy support device

Claims (8)

A radiation therapy support device for use in MR image-guided real-time adaptive radiation therapy, comprising:
a magnetic resonance image acquisition unit for acquiring magnetic resonance image data of a region including a planned target volume to be irradiated with a therapeutic radiation beam;
an image synthesis unit that synthesizes predetermined contour image data with the magnetic resonance image data acquired by the magnetic resonance image acquisition unit,
The magnetic resonance image acquisition unit includes:
a first magnetic resonance image data set which is a magnetic resonance image obtained while the therapeutic radiation beam is being irradiated;
and acquiring second magnetic resonance image data, which is a magnetic resonance image when the therapeutic radiation beam is not irradiated;
The radiation therapy support device according to claim 1, wherein the image synthesis unit synthesizes the contour image data, which includes image data of a contour of a macroscopic tumor volume and image data of a contour of the planning target volume, with the second magnetic resonance image data. The radiation therapy support device according to claim 1 , wherein the second magnetic resonance image data has a longer update time than the first magnetic resonance image data. 2. The radiation therapy support device according to claim 1, wherein the contour image data includes image data of a contour of an organ at risk or image data of a contour of a dose distribution. The radiation therapy support device according to claim 1 , wherein 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. 2. The radiation therapy support device according to claim 1, wherein 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. The radiation therapy support device according to claim 1 , 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. A radiation therapy support program for use in MR image-guided real-time adaptive radiation therapy, comprising:
On the computer,
a magnetic resonance image acquisition function for acquiring magnetic resonance image data of an area including a planned target volume to be irradiated with the therapeutic radiation beam;
an image synthesis function of synthesizing predetermined contour image data with the magnetic resonance image data acquired by the magnetic resonance image acquisition function;
The magnetic resonance image acquisition function includes:
a first magnetic resonance image data set which is a magnetic resonance image obtained while the therapeutic radiation beam is being irradiated;
and acquiring second magnetic resonance image data, which is a magnetic resonance image when the therapeutic radiation beam is not irradiated;
The radiation therapy support program, wherein the image synthesis function synthesizes the contour image data, including image data of a contour of a macroscopic tumor volume and image data of a contour of the planning target volume, with the second magnetic resonance image data. 1. A radiation therapy system for use in MR image-guided real-time adaptive radiation therapy, comprising:
a treatment planning unit for generating an irradiation plan including a planning target volume to be irradiated with the therapeutic radiation beam;
an irradiation unit that irradiates the therapeutic radiation beam based on the irradiation plan created by the treatment planning unit;
a magnetic resonance image acquisition unit that acquires magnetic resonance image data of a region including the planning target volume to be irradiated with the therapeutic radiation beam by the irradiation unit;
an image synthesis unit that synthesizes predetermined contour image data with the magnetic resonance image data acquired by the magnetic resonance image acquisition unit,
The magnetic resonance image acquisition unit includes:
a first magnetic resonance image data set which is a magnetic resonance image obtained while the therapeutic radiation beam is being irradiated;
and acquiring second magnetic resonance image data, which is a magnetic resonance image when the therapeutic radiation beam is not irradiated;
The radiation therapy system according to claim 1, wherein the image synthesis unit synthesizes the contour image data, which includes image data of a contour of a macroscopic tumor volume and image data of a contour of the planning target volume, with the second magnetic resonance image data.

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