Radiation therapy planning device and radiation therapy planning method

Abstract

To reduce deleterious events to a normal tissue in radiotherapy.SOLUTION: A radiotherapy planning apparatus according to an embodiment includes a setting unit, an acquisition unit, an evaluation unit, and an output unit. The setting unit sets a radiation irradiation condition to a medical image concerning a patient. The acquisition unit acquires a histogram of a dosage rate in a predetermined area of the patient based on the irradiation condition. The evaluation unit evaluates the irradiation condition based on the histogram. The output unit outputs information based on an evaluation result of the irradiation condition.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The embodiments disclosed in the present specification and drawings include a radiation therapy planning system and Radiation treatment planning By law Regarding. [Background technology]

[0002] In radiation therapy, there is a high-dose-rate, ultrashort-duration irradiation method called FLASH irradiation. FLASH irradiation selectively damages tumors without damaging normal tissue by delivering high-dose-rate radiation (e.g., 40 Gy / sec or more) in an ultrashort time. However, because the dose rate is reduced in the penumbra created by the aperture that limits the irradiation field, if the penumbra is irradiated onto normal tissue, the effects of FLASH irradiation cannot be achieved and there is a possibility of damaging normal tissue. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-220659 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to reduce adverse events to normal tissues during radiation therapy. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described below can also be positioned as other problems. [Means for solving the problem]

[0005] A radiation therapy planning device according to an embodiment includes a setting unit, an acquisition unit, an evaluation unit, and an output unit. The setting unit sets radiation irradiation conditions for a medical image of a patient. The acquisition unit acquires a histogram of radiation dose rates in a predetermined region of the patient based on the irradiation conditions. The evaluation unit evaluates the irradiation conditions based on the histogram. The output unit outputs information based on the evaluation results of the irradiation conditions. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a radiotherapy system according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of the radiation therapy planning apparatus according to the first embodiment. [Figure 3] FIG. 3 is a diagram showing a typical flow of treatment planning processing by the radiation treatment planning device. [Figure 4] FIG. 4 is a diagram showing a schematic view of a FLASH region and a normal irradiation region when the irradiation direction is "270 degrees" in a cross section parallel to the beam axis of radiation. [Figure 5] FIG. 5 is a diagram showing a schematic view of a FLASH region and a normal irradiation region when the irradiation direction is "270 degrees" in a cross section perpendicular to the beam axis of radiation. [Figure 6] FIG. 6 is a diagram showing the normal irradiation volume ratio. [Figure 7] FIG. 7 is a diagram showing an example of a display screen for the normal irradiation volume ratio and the determination result. [Figure 8] FIG. 8 is a diagram showing a schematic diagram of the irradiation condition change process. [Figure 9] FIG. 9 is a diagram showing an example of a display screen of the normal irradiation volume ratio and the determination result under the changed irradiation conditions. [Figure 10] FIG. 10 is a diagram showing a display example of the DVH in the FLASH area and the DVH in the normal illumination area. [Figure 11] FIG. 11 is a diagram showing an example of the configuration of a radiation therapy support apparatus according to the second embodiment. [Figure 12]FIG. 12 is a diagram showing a typical flow of treatment support processing by the radiation treatment support apparatus. [Figure 13] FIG. 13 is a diagram showing a series of processes related to obtaining the DrVH of the current position and the DrVH of the reference position. [Figure 14] FIG. 14 is a diagram showing an example of a display screen showing the DrVH of the current position and the DrVH of the reference position. [Figure 15] FIG. 15 is a diagram showing an example of the warning screen. [Figure 16] FIG. 16 is a diagram showing an example of projection of the correction direction and correction amount. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of a radiation therapy planning apparatus, a radiation therapy planning method, and a radiation therapy support apparatus will be described in detail with reference to the drawings.

[0008] The radiation therapy planning device and the radiation therapy support device according to this embodiment are included in a radiation therapy system.

[0009] Fig. 1 is a diagram showing an example of the configuration of a radiation therapy system 1 according to this embodiment. As shown in Fig. 1, the radiation therapy system 1 includes a medical image diagnostic apparatus 2, a radiation therapy planning apparatus 3, a radiation therapy apparatus 4, and a radiation therapy support apparatus 5. The medical image diagnostic apparatus 2, the radiation therapy planning apparatus 3, the radiation therapy apparatus 4, and the radiation therapy support apparatus 5 are communicably connected to each other via a network. The radiation therapy system 1 is a system that creates a treatment plan for radiation therapy for a patient and performs radiation therapy in accordance with the treatment plan.

[0010] The medical image diagnostic device 2 performs medical imaging on a patient to be treated and generates medical images to be used in treatment planning. The medical images may be two-dimensional images composed of two-dimensionally arranged pixels, or three-dimensional images composed of three-dimensionally arranged voxels. The medical image diagnostic device 2 may be any modality device capable of generating medical images. Examples of modality devices include an X-ray computed tomography device, a magnetic resonance imaging device, a cone-beam CT device, and a nuclear medicine diagnostic device. Data of the medical images is transmitted to, for example, a radiation treatment planning device 3.

[0011] The radiation therapy planning device 3 is a computer that creates a treatment plan for a patient using medical images generated by the medical image diagnostic device 2. Data on the treatment plan is supplied to a radiation therapy device 4 and a radiation therapy support device 5.

[0012] The radiation therapy device 4 treats the patient by irradiating the patient with radiation in accordance with the treatment plan created by the radiation therapy planning device 3. The radiation therapy device 4 has a treatment gantry and a treatment couch installed in a treatment room. The treatment couch moves its top plate so that the patient's treatment area is approximately aligned with the isocenter. The treatment gantry supports an irradiation head unit that is rotatable around a rotation axis. The irradiation head unit irradiates radiation in accordance with the treatment plan. Specifically, the irradiation head unit forms an irradiation field using a multi-leaf collimator, and this irradiation field suppresses irradiation of normal tissue. When radiation is irradiated to the treatment area, the treatment area disappears or shrinks.

[0013] The radiation therapy support device 5 is installed in a treatment room where the radiation therapy device 4 is installed or in a control room adjacent to the treatment room. The radiation therapy support device 5 is a computer that outputs guide information to guide the work related to radiation therapy.

[0014] Hereinafter, an embodiment relating to a radiation therapy planning device 3 will be described as a first embodiment, and an embodiment relating to a radiation therapy support device 5 will be described as a second embodiment.

[0015] (First embodiment) 2 is a diagram showing an example of the configuration of a radiation therapy planning device 3 according to the first embodiment. The radiation therapy planning device 3 includes a processing circuitry 31, a storage device 32, a display device 33, an input device 34, and a communication device 35.

[0016] The processing circuitry 31 has processors such as a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). When the processor starts a radiation therapy planning program installed in the storage device 32 or the like, the processor realizes an acquisition function 311, a condition setting function 312, a region specifying function 313, a calculation function 314, a determination function 315, and a display control function 316. Note that each of the functions 311-316 does not necessarily have to be realized by a single processing circuit. A processing circuit may be configured by combining multiple independent processors, and each processor may execute a program to realize each of the functions 311-316.

[0017] The processing circuitry 31 acquires various pieces of information by implementing the acquisition function 311. For example, the processing circuitry 31 acquires data of medical images received from the medical image diagnostic apparatus 2.

[0018] By implementing the condition setting function 312, the processing circuitry 31 sets radiation irradiation conditions for radiation therapy. The irradiation conditions include at least an irradiation field and an irradiation dose index value. The irradiation field is the area to which radiation is irradiated. The irradiation dose index value is the dose index value of the irradiated radiation. The dose index value includes a total dose indicating the total amount of irradiated dose and a dose rate indicating the dose irradiated per unit time.

[0019] By implementing the calculation function 314, the processing circuitry 31 calculates a volume index value of a region of normal tissue included in the irradiation field, the region having a predicted dose index value below the first threshold, based on the irradiation conditions set by the condition setting function 312. The predicted dose index value is a dose index value calculated by the processing circuitry 31 etc. when planning a radiation therapy, and is a predicted value of a dose index value to be irradiated at a position corresponding to each pixel of a medical image. Specifically, the predicted dose index value includes a predicted dose value which is a predicted value of a total dose and a predicted dose value which is a predicted value of a dose rate. The volume index value is an index value related to volume, and includes, for example, a volume, a volume ratio, etc.

[0020] By implementing the determination function 315, the processing circuitry 31 determines whether the irradiation conditions set by the condition setting function 312 are acceptable based on the volume index value calculated by the calculation function 314. More specifically, if the volume index value is greater than the second threshold, the processing circuitry 31 determines that the irradiation conditions are unacceptable, and if the volume index value is less than the second threshold, the processing circuitry 31 determines that the irradiation conditions are acceptable.

[0021] In the display control function 316, the processing circuitry 31 displays various information on the display device 33. For example, the processing circuitry 31 displays the volume index value calculated by the calculation function 314, the determination result by the determination function 315, etc.

[0022] The storage device 32 is a storage device such as a ROM (Read Only Memory), RAM (Random Access Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or semiconductor storage device that stores various information. In addition to the above storage devices, the storage device 32 may also be a portable storage medium such as a CD (Compact Disc), DVD (Digital Versatile Disc), or flash memory, or a drive that reads and writes various information from and to a semiconductor memory element. The storage device 32 may also be located in another computer connected to the radiation therapy planning device 3 via a network. For example, the storage device 32 stores a treatment planning program, etc.

[0023] The display device 33 displays various information in accordance with the display control function 316 of the processing circuit 31. For example, a liquid crystal display (LCD), a cathode ray tube (CRT) display, an organic electroluminescence display (OLED), a plasma display, or any other display can be used as appropriate as the display device 33. The display device 33 may also be a projector.

[0024] The input device 34 accepts various input operations from the user, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing circuit 31. Specifically, the input device 34 may be a mouse, keyboard, trackball, switch, button, joystick, touchpad, touch panel display, or the like, as appropriate. An electrical signal corresponding to the input operation to the input device is output to the processing circuit 31. The input device 34 may be a voice recognition device that converts a voice signal collected by a microphone into a command signal. The input device 34 may also be an input device provided in another computer connected via a network or the like.

[0025] The communication device 35 is an interface for communicating data with other devices included in the radiation therapy system 1. For example, the communication device 35 receives medical image data from the medical image diagnostic device 2 via the network. The communication device 35 also transmits treatment plan data to the radiation therapy device 4 and the radiation therapy support device 5 via the network.

[0026] Next, a description will be given of an example of the operation of the radiation therapy planning device 3. In the following description, it is assumed that the medical images are three-dimensional CT images collected by an X-ray computed tomography device.

[0027] Fig. 3 is a diagram showing a typical flow of treatment planning processing by the radiation therapy planning device 3. As shown in Fig. 3, the processing circuitry 31 first acquires a medical image of a patient (step SA1) by implementing the acquisition function 311. The medical image acquired in step SA1 depicts the patient's anatomical structure.

[0028] After step SA1 is performed, the processing circuitry 31, by implementing the region identification function 313, identifies tumors, normal normal tissues, and risk organs from the medical image acquired in step SA1 (step SA2). The tumor is the target of radiation therapy. The normal normal tissues and risk organs are normal tissues other than the tumor. The risk organs are normal tissues that are particularly sensitive to radiation. The normal normal tissues are normal tissues other than the risk organs. The identification method may be any method. For example, it may be performed manually by the user. Specifically, the identification is performed according to the following procedure. First, the processing circuitry 31 displays the medical image on the display device 33. The user draws outlines surrounding each of the tumors, normal normal tissues, and risk organs depicted in the medical image via an input device 34 such as a mouse or tablet pen. The processing circuitry 31 identifies the image regions surrounded by the outlines as tumors, normal normal tissues, or risk organs. If there are multiple tumors, normal normal tissues, and risk organs, they are identified individually.

[0029] The identification method is not limited to the above method, and may be performed automatically by image processing. For example, the processing circuitry 31 can identify tumors, normal tissues, and risk organs by performing threshold processing or image recognition processing on medical images.

[0030] When step SA2 is performed, the processing circuitry 31 sets provisional irradiation conditions by implementing the condition setting function 312 (step SA3). In step SA3, the processing circuitry 31 sets the irradiation field, irradiation direction, and irradiation dose index value as irradiation conditions. The irradiation field is set on the medical image. The irradiation direction is the direction in which radiation is irradiated. The irradiation direction is defined by the angle around the rotation center axis of the treatment gantry of the radiation therapy device 4. The irradiation dose index value includes the irradiation dose and the irradiation dose rate. The irradiation dose is defined as the total dose of radiation irradiated in radiation therapy performed over multiple days. The irradiation dose rate is defined as the dose of radiation per unit time.

[0031] When step SA3 is performed, the processing circuitry 31 identifies a FLASH region and a normal irradiation region in the irradiation field set in step SA3 by implementing the region identification function 313 (step SA4). In step SA4, the processing circuitry 31 identifies, from the irradiation field set in step SA3, the irradiation region irradiated with irradiation rays due to the penumbra as the normal irradiation region, and identifies the irradiation region irradiated with irradiation rays not due to the penumbra as the FLASH region.

[0032] 4 and 5 are diagrams showing a schematic view of the FLASH region and the normal irradiation region when the irradiation direction is "270 degrees." FIG. 4 shows a cross section of the medical image parallel to the beam axis of the radiation. FIG. 5 shows a cross section of the medical image perpendicular to the beam axis of the radiation. As shown in FIGS. 4 and 5, the medical image includes a tumor region RA and a normal tissue region RB. The tumor region RA is an image region related to the tumor identified in step SA3. The normal tissue region RB is an image region related to normal normal tissue and / or risk organs identified in step SA3.

[0033] As shown in Figures 4 and 5, the irradiation field R1 is set to surround the tumor region RA. An area reduced by a predetermined distance from the irradiation field R1 is set as the FLASH region R2. The area between the irradiation field R1 and the FLASH region R2 is set as the normal irradiation region R3. The normal irradiation region R3 is an area irradiated with radiation that has passed through an aperture provided in the radiotherapy device 4, i.e., penumbra. The predetermined distance may be set arbitrarily depending on the geometric conditions of the radiotherapy device 4, etc. The predetermined distance in this embodiment is assumed to be approximately 5 mm. The FLASH region R2 is an area irradiated with direct rays that do not pass through an aperture provided in the radiotherapy device 4, i.e., radiation that does not rely on penumbra, thereby achieving FLASH irradiation.

[0034] As described above, FLASH irradiation is a radiation irradiation method that selectively damages tumors without damaging normal tissues by irradiating ultra-high doses of radiation in a short period of time. The effect of selectively damaging tumors without damaging normal tissues is called the FLASH irradiation effect. Because the dose rate to the normal irradiation region R3 is lower than the dose rate of FLASH irradiation, the FLASH irradiation effect cannot be achieved in the normal irradiation region R3. However, because the normal irradiation region R3 is irradiated with radiation at a higher dose rate than the dose rate of normal radiation therapy, there is a risk of excessive damage to normal tissues. Therefore, it is appropriate as an irradiation condition for the volume of the normal tissue region RB overlapping the normal irradiation region R3 to be as small as possible.

[0035] After step SA4, the processing circuitry 31, by implementing the calculation function 314, generates a spatial distribution of the predicted dose rate for the irradiation field identified in step SA3 (step SA5). In step SA5, the processing circuitry 31 generates the spatial distribution of the predicted dose rate according to an arbitrary dose calculation algorithm based on the irradiation conditions and the medical image. The predicted dose rate is calculated as a predicted value of the administered dose rate for one FLASH irradiation. In this case, the processing circuitry 31 assigns a predicted dose rate reduced by the aperture to the normal irradiation region and a predicted dose rate not reduced by the aperture to the FLASH region to generate the spatial distribution of the predicted dose rate. Examples of the dose calculation algorithm that can be used include the equivalent TAR (tissue-air ratio) method, the differential scattered air dose ratio method, the small volume method, the Monte Carlo method, and the convolution method.

[0036] After step SA5 is performed, the processing circuitry 31, by implementing the calculation function 314, generates a frequency distribution (DrVH) of predicted dose rates for each of the tumor, normal normal tissue, and risk organs identified in step SA2 (step SA6). For example, the processing circuitry 31 identifies a predicted dose rate assigned to each pixel in the normal tissue region corresponding to each of the normal tissue region and the risk organ, and calculates a volume index value for each predicted dose rate. The processing circuitry 31 can generate the DrVH by recording the volume index value for each predicted dose rate. As the volume index value, volume or volume ratio may be used. The volume may be defined as the number of pixels, or may be defined as the number of pixels multiplied by the volume of one pixel. The volume ratio is defined as the ratio of the volume of each predicted dose rate to the total volume of the normal tissue region. Hereinafter, the volume index value is referred to as the volume ratio. The processing circuitry 31 can similarly generate a DrVH for each tumor region.

[0037] When step SA6 is performed, processing circuitry 31, by implementing calculation function 314, calculates the volume fraction below the FLASH effect threshold (step SA7). The calculated volume fraction is called the normal irradiation volume fraction. Specifically, in step SA7, processing circuitry 31 applies the FLASH effect threshold to the DrVH of the normal tissue region generated in step SA6 to calculate the normal irradiation volume fraction.

[0038] FIG. 6 is a diagram showing a normal irradiation volume fraction. As shown in FIG. 6, in step SA6, the processing circuitry 31 generates a frequency distribution (DrVH) 61 of the volume fraction (Volume [%]) of the predicted dose rate (Dose_rate [Gy / s]). The DrVH 61 is a graph in which the horizontal axis is defined as the predicted dose rate and the vertical axis is defined as the volume fraction. Next, the processing circuitry 31 sets a FLASH effect threshold Th for the DrVH. The FLASH effect threshold Th is defined as the predicted dose rate at which a therapeutic effect (FLASH effect) can be obtained by FLASH irradiation. For example, the FLASH effect threshold Th is set to 40 Gy / s, etc. The FLASH effect threshold Th may be set for each organ. The processing circuitry 31 calculates a volume fraction 71 below the FLASH effect threshold as a normal irradiation volume fraction based on the DrVH generated in step SA6. The normal irradiation volume fraction 71 means a volume fraction at which the FLASH effect cannot be obtained.

[0039] When step SA7 is performed, the processing circuitry 31, by implementing the determination function 315, determines whether the irradiation conditions set in step SA3 are within the allowable range (step SA8). Specifically, the processing circuitry 31 determines whether the normal irradiation volume ratio calculated in step SA7 exceeds a predetermined determination threshold. The determination threshold is set to, for example, the upper limit of the allowable normal irradiation volume ratio. If the normal irradiation volume ratio calculated in step SA7 exceeds the determination threshold, the processing circuitry 31 determines that the irradiation conditions are not within the allowable range. On the other hand, if the normal irradiation volume ratio calculated in step SA7 does not exceed the determination threshold, the processing circuitry 31 determines that the irradiation conditions are within the allowable range.

[0040] When step SA8 is performed, the processing circuitry 31 displays the normal irradiation volume ratio calculated in step SA7 and the determination result obtained in step SA8 (step SA9) by implementing the display control function 316. In step SA9, the processing circuitry 31 displays the normal irradiation volume ratio and the determination result in a predetermined layout on the display device 33.

[0041] FIG. 7 is a diagram showing an example of a display screen I1 for the normal irradiation volume ratio and the determination result. The display screen I1 is displayed on the display device 33. As shown in FIG. 7, the display screen I1 includes a display area I11 for the DrVH 61, a display area I12 for the irradiation conditions, a display area I13 for the normal irradiation region, a display area I14 for the FLASH region, and a display area I15 for the determination result. The DrVH 61 is displayed in the display area I11. The normal irradiation volume ratio may be emphasized in the DrVH 61. The irradiation conditions are displayed in the display area I12. The value (e.g., 26%) of the volume ratio of the normal irradiation region (normal irradiation volume ratio) is displayed in the display area I13. The value (e.g., 74%) of the volume ratio of the FLASH region is displayed in the display area I14. The volume ratio of the FLASH region is calculated by subtracting the normal irradiation volume ratio from 100%. The display area I15 displays a message according to the determination result of the determination process executed in step SA8. For example, if it is determined in step SA8 that the irradiation conditions are not within the allowable range, a message such as "Normally, the irradiation volume ratio is high" or "Please change the irradiation conditions" is displayed.

[0042] After step SA9 is performed, the processing circuitry 31 determines whether or not to change the irradiation conditions by implementing the determination function 315 (step SA10).

[0043] As shown in FIG. 7, a change button I16 and a confirm button I17 are displayed on the display screen I1. The change button I6 is a GUI (Graphical User Interface) button for instructing a change of the irradiation conditions. The confirm button I7 is a GUI button for instructing a confirmation of the irradiation conditions. The user observes the determination results and the normal irradiation volume ratio displayed on the display screen I1, and when the user determines that the irradiation conditions should be changed, the user presses the change button I16 via the input device 34 or the like. When the change button I16 is pressed, the processing circuitry 31 determines to change the irradiation conditions in step SA10.

[0044] If it is determined in step SA10 that the irradiation conditions are to be changed (step SA10: YES), the processing circuitry 31 sets new irradiation conditions by implementing the condition setting function 312 (step SA3). That is, the processing circuitry 31 changes parameter values ​​of irradiation conditions, such as the irradiation field, irradiation direction, irradiation dose, and irradiation dose rate, in accordance with a user's instruction via the input device 34 or a predetermined algorithm. The processing circuitry 31 may change the parameter values ​​of the irradiation conditions so that the normal irradiation volume fraction becomes smaller, or so that the normal irradiation volume fraction becomes smaller than a determination threshold. For example, the processing circuitry 31 may determine a conditional expression indicating a correspondence relationship between the parameter values ​​of the irradiation conditions and the normal irradiation volume fraction, and calculate the parameter values ​​of the irradiation conditions that minimize the normal irradiation volume fraction based on the conditional expression. Alternatively, the processing circuitry 31 may determine the parameter values ​​of the irradiation conditions that minimize the normal irradiation volume fraction using a Gaussian process regression model such as Bayesian optimization. The processing circuitry 31 may also randomly change the parameter values ​​of the irradiation conditions. Alternatively, the processing circuitry 31 may change the irradiation conditions to parameter values ​​designated by the user via the input device 34 .

[0045] 8 is a diagram showing a schematic diagram of the irradiation condition change process. As shown in FIG. 8, when the irradiation direction is 270 degrees, the normal tissue region RB overlaps the normal irradiation region R3 over a wide area, the normal irradiation volume ratio is larger than the judgment threshold, and it is determined in step SA8 that the irradiation conditions are not within the allowable range. On the other hand, when the irradiation direction is 0 degrees, the normal tissue region RB overlaps the normal irradiation region R3 only over a relatively narrow area. In this case, the processing circuitry 31 changes the irradiation direction from 270 degrees to 0 degrees, as shown in FIG. 8.

[0046] When the irradiation conditions are changed in step SA3, the processing circuitry 31 executes steps SA4-SA9 as described above. That is, the processing circuitry 31 calculates a changed volume index value based on the changed irradiation conditions, and determines whether the changed irradiation conditions are acceptable based on the changed volume index value. In step SA9, the processing circuitry 31 may display the normal irradiation volume fraction calculated under the changed irradiation conditions in step SA7 and the determination result of step SA8, or may display this information together with the normal irradiation volume fraction under the irradiation conditions before the change.

[0047] 9 is a diagram showing an example of a display screen I2 showing the normal irradiation volume ratio and the determination result under the changed irradiation conditions. As shown in FIG. 9, the display screen I2 includes a display area I21 for the changed DrVH 62, a display area I22 for the irradiation conditions, a display area I23 for the normal irradiation area, a display area I24 for the FLASH area, a display area I25 for the determination result, a change button I26, and a confirm button I27. The display areas I22, I23, I24, I25, the change button I26, and the confirm button I27 are substantially equivalent to the display areas I12, I13, I14, I15, the change button I16, and the confirm button I17 in FIG. 7, respectively.

[0048] As shown in FIG. 9 , the display area I21 displays a graph of DrVH 62 calculated under the changed irradiation conditions and DrVH 61 calculated under the previous irradiation conditions. For example, the processing circuit 31 displays the changed DrVH 62 and the previous DrVH 61 in different visual modes, such as different line types or colors. By observing the changed DrVH 62 and the previous DrVH 61, the user can understand the change in the normal irradiation volume ratio due to the change in the irradiation conditions. The display area I25 displays a message corresponding to the determination result of the determination process executed in step SA8. For example, if it is determined in step SA8 that the irradiation conditions are within the allowable range, a message such as "The normal irradiation volume ratio is low" or "The irradiation conditions are appropriate" is displayed.

[0049] When step SA9 is performed, the processing circuitry 31 determines whether or not to change the irradiation conditions by implementing the determination function 315 (step SA10). The user observes the determination result and the normal irradiation volume ratio displayed on the display screen I2, and if the user determines that the irradiation conditions do not need to be changed, the user presses the confirm button I27 via the input device 34 or the like. When the confirm button I27 is pressed, the processing circuitry 31 determines in step SA10 that the irradiation conditions will not be changed.

[0050] If it is determined in step SA10 that the irradiation conditions should not be changed (step SA10: NO), the processing circuit 31 sets the current irradiation conditions set in step SA3 as the final version by implementing the condition setting function 312 (step SA11).

[0051] As described above, the processing circuitry 31 can search for optimal irradiation conditions in which the normal irradiation volume ratio is smaller than the determination threshold by repeating steps SA3 to SA10. The finalized irradiation conditions are stored in the storage device 32 and transmitted to the radiotherapy device 4 and the radiotherapy support device 5.

[0052] When step SA11 is performed, the treatment planning process ends by the radiation treatment planning device 3. Thereafter, the radiation treatment device 4 irradiates the patient with radiation in accordance with the finalized irradiation conditions, and performs radiation treatment.

[0053] 3 is an example, and is not limited to this, and various modifications are possible. Some modifications will be described below.

[0054] In the above processing example, it is determined in step SA10 whether or not the irradiation conditions need to be changed. However, this embodiment is not limited to this. For example, if it is determined in step SA8 that the irradiation conditions are not within the allowable range, the processing circuitry 31 may determine that the irradiation conditions need to be changed, and if it is determined in step SA8 that the irradiation conditions are within the allowable range, the processing circuitry 31 may determine that the irradiation conditions need not be changed.

[0055] In the above processing example, a frequency distribution (DrVH) of predicted dose rates is generated (step SA6) and displayed (step SA9). However, this embodiment is not limited to this. For example, the processing circuitry 31 may generate a frequency distribution (DVH) of predicted doses for each of the FLASH region and normal irradiation region set in step SA4 and display it on the display device 33.

[0056] FIG. 10 is a diagram showing a display example of DVH 64 of the FLASH region and DVH 65 of the normal irradiation region. As shown in FIG. 10, DVH 64 and DVH 65 are graphs in which the horizontal axis is defined as the predicted dose (Dose [Gy]) and the vertical axis is defined as the volume ratio (Volume [%]). By displaying the DVH, the user can check the total dose irradiated to the patient for the FLASH region and the normal irradiation region separately. Note that the processing circuitry 31 may generate and display a DVH of the sum of the FLASH region and the normal irradiation region. This allows the user to compare the DVH of the FLASH region and / or the normal irradiation region with the sum of the regions (total region).

[0057] When the irradiation field includes multiple normal tissues (organs), such as the heart and stomach, the processing circuitry 31 may generate and display a DrVH and / or DVH for each normal tissue, or may calculate and display a normal irradiation volume ratio. In this case, the processing circuitry 31 may display only the DrVH and / or DVH for a specific organ, or may display multiple DrVHs and / or DVHs for multiple organs. The processing circuitry 31 may display the DrVH and normal irradiation volume ratio for each organ as a graph or as a numerical value, as shown in FIG. 6, etc. By generating and displaying a DrVH for each organ, or by calculating and displaying the normal irradiation volume ratio, it is possible to more precisely distinguish between regions to which the FLASH effect is applied and regions to which it is not applied. Furthermore, the processing circuitry 31 may display a DrVH for each organ, as well as a DrVH for all normal organs as a single region.

[0058] As described above, the radiation therapy planning device 3 according to the first embodiment includes the processing circuitry 31. The processing circuitry 31 sets radiation irradiation conditions. The irradiation conditions include at least a radiation irradiation field and an irradiation dose index value set in a medical image. Based on the irradiation conditions, the processing circuitry 31 calculates a volume index value of a region of normal tissue included in the irradiation field, the region relating to a predicted dose index value below the FLASH effect threshold. The processing circuitry 31 determines whether the irradiation conditions are acceptable based on the volume index value.

[0059] According to the above configuration, it is possible to determine whether irradiation conditions are acceptable or not depending on the volume index value of the region of normal tissue where the FLASH effect can be obtained. This makes it possible to search for irradiation conditions that result in a relatively small volume index value of the region where the FLASH effect cannot be obtained. Therefore, safe and highly accurate radiation therapy that can reduce adverse events to normal tissue is possible in ultra-high dose rate short-time irradiation methods such as FLASH irradiation.

[0060] In the above processing example, the processing circuitry 31 determines that the illumination conditions are not within the acceptable range when the volume index value of the area below the FLASH effect threshold exceeds the judgment threshold. However, this embodiment is not limited to this. For example, the processing circuitry 31 may assume that the normal illumination area can be considered the same as the area where the FLASH effect cannot be obtained, and determine that the illumination conditions are not within the acceptable range when the volume index value of the normal illumination area identified in step SA3 exceeds the threshold, and determine that the illumination conditions are within the acceptable range when the volume index value of the normal illumination area is below the threshold. This makes it possible to easily determine the appropriateness of the illumination conditions based on the volume index value of the area where the FLASH effect is not expected to be obtained.

[0061] From another perspective, the processing circuitry 31 of the radiation therapy planning device 3 according to the first embodiment executes setting processing, acquisition processing, evaluation processing, and output processing. In the setting processing, the processing circuitry 31 sets radiation irradiation conditions for a medical image of a patient. The irradiation conditions include an irradiation field, a total dose, a dose rate, etc., and are set by a condition setting function 312. In the acquisition processing, the processing circuitry 31 acquires a histogram (DrVH) of radiation dose rates in a predetermined region of the patient based on the irradiation conditions. The DrVH may be generated by the processing circuitry 31 of the radiation therapy planning device 3 or by another computer. In the latter case, the processing circuitry 31 receives the DrVH via the communication device 35 from the computer that generated the DrVH or the computer that stores the DrVH. The predetermined region is the irradiation field or a tumor, normal region, normal normal tissue, and / or risk organs included in the irradiation field. In the evaluation processing, the processing circuitry 31 evaluates the irradiation conditions based on the DrVH. In the output processing, the processing circuitry 31 outputs information based on the evaluation results of the irradiation conditions. The information output from the processing circuit 31 may be displayed on the display device 3, may be stored in the storage device 32, or may be transferred to another computer via the communication device 35.

[0062] According to the above configuration, the irradiation conditions are evaluated based on DrVH, which is the frequency distribution of the dose rate, so that it is possible to easily determine whether the irradiation conditions for the FLASH irradiation method are appropriate.

[0063] In the evaluation process, the processing circuit 31 may determine the appropriateness of the illumination conditions based on the DrVH. Specifically, the processing circuit 31 determines the appropriateness of the illumination conditions based on a comparison between a first threshold (determination threshold) and a volume ratio of a first region (normal illumination region) in the DrVH where the illumination effect of FLASH is not obtained or a second region (FLASH region) where the illumination effect of FLASH is obtained. Specifically, if the volume ratio of the normal illumination region to the illumination region is larger than the first determination threshold, the illumination conditions are determined to be inappropriate. If the volume ratio is smaller than the first determination threshold, the illumination conditions are determined to be appropriate. If the volume ratio of the FLASH region to the illumination region is larger than the second determination threshold, the illumination conditions are determined to be appropriate. If the volume ratio is smaller than the second determination threshold, the illumination conditions are determined to be inappropriate. Note that the processing circuit 31 does not have to determine the appropriateness of the illumination conditions. For example, the processing circuitry 31 may display the DrVH and the determination threshold on the display device 33. By checking the position of the determination threshold in the DrVH, the user can estimate the volume ratio of the normal irradiation area or the FLASH area and determine whether the irradiation conditions are appropriate.

[0064] The processing circuitry 31 according to the first embodiment may further execute a specification process, in which the processing circuitry 31 specifies a normal irradiation region and a FLASH region in a medical image or DrVH relating to a predetermined region.

[0065] In the identification process, the processing circuitry 31 identifies a penumbra region in a predetermined region as a normal irradiation region, and identifies a region other than the penumbra region in the predetermined region as a FLASH region. As one example, the processing circuitry 31 identifies a penumbra region and a non-penumbra region based on an operator's region designation of a predetermined region in a medical image. As another example, the processing circuitry 31 identifies a penumbra region based on an operator's region designation of a predetermined region in a medical image, and identifies the region other than the penumbra region in the predetermined region as a non-penumbra region. As another example, the processing circuitry 31 identifies a non-penumbra region based on an operator's region designation of a predetermined region in a medical image, and identifies the region other than the non-penumbra region in the predetermined region as a penumbra region. As another example, the processing circuitry 31 may identify a determination region and a non-penumbra region from within a predetermined region of a medical image based on parameters defining an irradiation field.

[0066] In the identification process, the processing circuitry 31 may identify the normal irradiation region and the FLASH region based on at least one of the irradiation depth of the radiation in the irradiation region, the radiation absorption characteristics of the tissue in the irradiation region, and the penumbra in the irradiation region. The irradiation depth refers to the distance from the body surface along the radiation irradiation direction. Specifically, the processing circuitry 31 identifies the penumbra region and the non-penumbra region in the irradiation region of the medical image using the above method. Next, the processing circuitry 31 calculates a predicted dose rate for each pixel in the irradiation region based on the irradiation conditions. In this case, for the penumbra region, the processing circuitry 31 calculates the predicted dose rate taking into account the attenuation of radiation according to the penumbra. Furthermore, the processing circuitry 31 calculates the predicted dose rate taking into account at least one of the attenuation rate of radiation according to the irradiation depth of the radiation in the irradiation region and the attenuation rate of radiation according to the radiation absorption characteristics of the tissue. The attenuation rate of radiation according to the irradiation depth and the radiation absorption characteristics of the tissue may be experimentally determined values ​​or may be values ​​obtained by predictive calculation. The processing circuitry 31 identifies regions where the predicted dose rate is below the FLASH effect threshold as normal irradiation regions, and identifies regions where the predicted dose rate is above the FLASH effect threshold as FLASH regions.

[0067] In the identification process, the processing circuitry 31 may identify a normal irradiation region and a FLASH region in the DrVH based on the DrVH and the FLASH effect threshold. As an example, the processing circuitry 31 identifies a region in the DrVH where the predicted dose rate is below the FLASH effect threshold as a normal irradiation region, and identifies a region in the DrVH where the predicted dose rate is above the FLASH effect threshold as a FLASH region. In this case, it is not necessarily necessary to identify a normal irradiation region and a FLASH region in the medical image.

[0068] In the determination process, the processing circuitry 31 may determine the appropriateness of the irradiation conditions based on a comparison between the predicted dose for tissue in the normal irradiation area and the tolerable dose of the tissue. The determination of the appropriateness of the irradiation conditions using the tolerable dose is, for example, performed when the irradiation conditions are determined to be applicable in the determination of the appropriateness of the irradiation conditions using DrVH. The tolerable dose is a radiation dose that can be tolerated. The tolerable dose differs for each tissue. For example, the processing circuitry 31 identifies the tolerable dose of tissue in the normal irradiation area using a tolerable dose table. The tolerable dose table is a LUT (Look Up Table) that records the tolerable dose for each tissue type. The tissue type refers to the anatomical name or symbol of the tissue. The processing circuitry 31 identifies the type of tissue in the normal irradiation area using anatomical landmarks, etc., and searches the tolerable dose table using the identified tissue type as a search key to determine the tolerable dose of the tissue. Meanwhile, the processing circuitry 31 generates a spatial distribution of the predicted dose. The processing circuitry 31 identifies the tissue to be treated within the normal irradiation region, identifies the predicted dose of the tissue by referring to the spatial distribution of the predicted dose, and compares the identified predicted dose with the tissue's tolerable dose. If the predicted dose exceeds the tolerable dose, the irradiation conditions are determined to be inappropriate, and if the predicted dose is below the tolerable dose, the irradiation conditions are determined to be appropriate. This determination process determines the appropriateness of the irradiation conditions using not only the volume fraction of the normal irradiation region and / or the FLASH region but also the tolerable dose, thereby making it possible to further reduce unnecessary exposure to normal tissue, etc. Note that determining the appropriateness of the irradiation conditions using the tolerable dose may be performed instead of determining the appropriateness of the irradiation conditions using DrVH.

[0069] In the output process, the processing circuit 31 displays information based on the appropriateness of the irradiation conditions on the display device 33. The information based on the appropriateness of the irradiation conditions may be information indicating that the irradiation conditions are appropriate or information indicating that the irradiation conditions are inappropriate, or may be information encouraging the start of radiation therapy based on the appropriate irradiation conditions or information encouraging a change in the irradiation conditions based on the inappropriate irradiation conditions. An example of information indicating that the irradiation conditions are appropriate is "The normal irradiation volume ratio is low. The irradiation conditions are appropriate," which is displayed in display field I25 in Figure 9. An example of information encouraging a change in the irradiation conditions is "The normal irradiation volume ratio is high. Please change the irradiation conditions," which is displayed in display field I15 in Figure 7.

[0070] In the output process, the processing circuitry 31 displays the normal irradiation region and the FLASH region on the display device 33 so that they can be distinguished from each other. As an example, the processing circuitry 31 displays the normal irradiation region (the region drawn with diagonal lines) and the FLASH region (the region drawn with white lines) in the DrVH so that they are visually distinguished from each other, as shown in FIG. 7. In this case, the processing circuitry 31 may attach a mark representing the determination threshold to the DrVH. As an example of the mark, a boundary line representing the determination threshold Th in FIG. 7 is displayed. As another example, the processing circuitry 31 may display the normal irradiation region and the FLASH region in the medical image so that they are visually distinguished from each other.

[0071] In the output process, the processing circuitry 31 may display a numerical value representing the volume ratio of the normal illumination area and / or the FLASH area on the display device 33. For example, as shown in Fig. 7, the processing circuitry 31 may display both the numerical value "26%" representing the volume ratio of the normal illumination area and the numerical value "74%" representing the volume ratio of the FLASH area.

[0072] (Second embodiment) 11 is a diagram showing an example of the configuration of a radiation therapy support device 5 according to the second embodiment. The radiation therapy support device 5 includes a processing circuit 51, a storage device 52, a display device 53, an input device 54, and a communication device 55.

[0073] The processing circuitry 51 has processors such as a CPU and a GPU. When the processor starts a radiation therapy planning program installed in the storage device 32 or the like, the processor realizes an acquisition function 511, a calculation function 512, a distribution display function 513, a determination function 514, and a warning function 515. Note that each of the functions 511-515 does not necessarily have to be realized by a single processing circuit. A processing circuit may be configured by combining multiple independent processors, and each processor may execute a program to realize each of the functions 511-515.

[0074] The processing circuitry 51 acquires various information by implementing the acquisition function 511. For example, the processing circuitry 51 acquires data on the predicted dose rate frequency distribution (DrVH) and the normal irradiation volume ratio received from the radiation therapy planning device 3.

[0075] By implementing the calculation function 512, the processing circuitry 51 calculates the positional deviation of the patient placed on the treatment couch of the radiotherapy device 4. Specifically, the processing circuitry 51 calculates the positional deviation between the current position of the patient placed on the couch of the radiotherapy device 4 and a reference position.

[0076] By implementing the distribution display function 513, the processing circuitry 51 displays the frequency distribution (DrVH) of predicted dose index values ​​for the current position and the frequency distribution (DrVH) of predicted dose index values ​​for the reference position. For example, the processing circuitry 51 displays the DrVH for the current position and the DrVH for the reference position on the display device 53.

[0077] By implementing the determination function 514, the processing circuitry 51 determines whether the positional deviation calculated by the calculation function 512 is acceptable based on a comparison between the volume index value of a region of the patient's normal tissue corresponding to the current position, the region having a predicted dose index value below the first threshold, and the reference volume index value. The reference volume index value is the volume index value of a region of the patient's normal tissue corresponding to the reference position, the region having a predicted dose index value below the first threshold. The normal irradiation volume ratio of the first embodiment may be used as the volume index value of the region having a predicted dose index value below the first threshold. The first threshold is set to the FLASH effect threshold of the first embodiment.

[0078] By realizing the warning function 515, the processing circuit 51 issues a warning when the determination function 514 determines that the positional deviation is not permissible. The warning may be issued as a warning message via the display device 53 or as a warning sound via a speaker.

[0079] The storage device 52 is a storage device such as a ROM, RAM, HDD, SSD, or integrated circuit storage device that stores various information. In addition to the above storage devices, the storage device 52 may also be a portable storage medium such as a CD, DVD, or flash memory, or a drive that reads and writes various information from and to a semiconductor memory element. The storage device 52 may also be located in another computer connected to the radiation therapy support device 5 via a network. For example, the storage device 52 stores a treatment support program, etc.

[0080] The display device 53 displays various information. For example, a liquid crystal display, a CRT display, an organic EL display, a plasma display, or any other display can be used as the display device 53. The display device 53 may also be a projector.

[0081] The input device 54 accepts various input operations from the user, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing circuit 51. Specifically, the input device 54 may be a mouse, keyboard, trackball, switch, button, joystick, touchpad, touch panel display, or the like, as appropriate. An electrical signal corresponding to the input operation to the input device is output to the processing circuit 51. The input device 54 may be a voice recognition device that converts a voice signal collected by a microphone into a command signal. The input device 54 may also be an input device provided in another computer connected via a network or the like.

[0082] The communication device 55 is an interface for communicating data with other devices included in the radiation therapy system 1. For example, the communication device 55 acquires data on the predicted dose rate frequency distribution (DrVH) and the normal irradiation volume fraction received from the radiation therapy planning device 3.

[0083] Next, a description will be given of an example of the operation of the radiation therapy support device 5. In the following description, it is assumed that the medical images are three-dimensional medical images collected by an X-ray computed tomography apparatus.

[0084] FIG. 12 is a diagram showing a typical flow of treatment support processing by the radiation treatment support apparatus 5.

[0085] As shown in FIG. 12, the processing circuitry 51 calculates the positional deviation of the patient by implementing the positional deviation calculation function 512 (step SB1). In step SB1, the processing circuitry 51 calculates the positional deviation between the current position of the patient and the reference position. The current position of the patient may be acquired by any method. For example, a user optically scans a patient placed on a bed using a shape measurement device that applies 3D optical scanning. The shape measurement device generates a graphical model of the patient's appearance (hereinafter referred to as the patient model) based on the scan data, which is series data of position information of sample points. The patient model at the current position is stored in the storage device 52 of the radiation therapy support device 5. Meanwhile, the storage device 52 stores a patient model at a reference position that was generated in advance. The reference position is the position of the patient at the time of treatment planning. In other words, the reference position is, for example, the position of the patient at the time of collecting medical images for treatment planning.

[0086] The processing circuitry 51 places the patient model in the current position and the patient model in the reference position in the same image processing coordinate system, and calculates the positional deviation between the patient model in the current position and the patient model in the reference position. The positional deviation is defined by a combination of a direction (hereinafter referred to as the positional deviation direction) and a distance (hereinafter referred to as the positional deviation amount). The positional deviation direction is represented, for example, by the craniocaudal, left-right, and front-to-back directions of the patient. The positional deviation amount is defined as a distance from the reference position. Specifically, the positional deviation calculation is performed as follows. First, the processing circuitry 51 identifies the same anatomical references for the patient model in the current position and the patient model in the reference position, and then calculates the positional deviation direction and the positional deviation amount from the anatomical references of the patient model in the reference position to the anatomical references of the patient model in the current position.

[0087] When step SB1 is performed, the processing circuitry 51 determines whether or not there is a positional deviation by implementing the positional deviation calculation function 512 (step SB2). In step SB2, the processing circuitry 51 compares the amount of positional deviation calculated in step SB1 with a threshold value. The threshold value may be set to any value, such as 0. If the amount of positional deviation is below the threshold value, the processing circuitry 51 determines that there is no positional deviation (step SB2: NO). In this case, the treatment support process shown in FIG. 12 ends. If the amount of positional deviation is above the threshold value, the processing circuitry 51 determines that there is a positional deviation.

[0088] If it is determined in step SB2 that there is a positional deviation (step SB2: YES), the processing circuit 51, by implementing the acquisition function 511, acquires the frequency distribution (DrVH) of the predicted dose rate corresponding to the current position and the frequency distribution (DrVH) of the predicted dose rate at the reference position (step SB3).

[0089] FIG. 13 is a diagram showing a series of processes related to obtaining the DrVH of the current position and the DrVH of the reference position. As shown in FIG. 13, the reference position and current position of the patient are obtained. It is assumed that the current position is shifted 3 cm caudally from the reference position. In step SB1, the positional shift between the reference position and the current position is calculated. In the case of FIG. 13, the positional shift direction is caudal, and the positional shift amount is 3 cm.

[0090] In step SB3, the storage device 32 stores the DrVH and the normal irradiation volume ratio in association with each other for each of a plurality of combinations of misalignment direction and misalignment amount. The DrVH and the normal irradiation volume ratio for each of the plurality of combinations are generated and calculated in advance by the radiation therapy planning device 3. For example, the processing circuitry 31 of the radiation therapy planning device 3 generates and calculates the DrVH and the normal irradiation volume ratio when the patient's organ is shifted at predetermined intervals in the craniocaudal, left-right, and anterior-posterior directions around the reference position. The DrVH and the normal irradiation volume ratio are generated and calculated according to the finalized irradiation conditions.

[0091] 13, if it is determined in step SB2 that there is a positional deviation, the DrVH of the reference position and the DrVH of the current position are obtained from the storage device 52. In the case of FIG. 13, the DrVH of the current position is obtained as the DrVH at a position 3 cm caudal to the reference position.

[0092] When step SB3 is performed, the processing circuit 51 displays the DrVH of the current position and the DrVH of the reference position acquired in step SB3 (step SB4) by implementing the distribution display function 513. In step SB4, the processing circuit 51 displays the DrVH of the current position and the DrVH of the reference position on the display device 53 in a predetermined layout.

[0093] FIG. 14 is a diagram showing an example of a display screen I3 showing the DrVH at the current position and the DrVH at the reference position. The display screen I3 is displayed on the display device 53. As shown in FIG. 14, the display screen I3 includes a DrVH display area 31 and a message display area I32. The display area I31 displays the DrVH 71 at the current position and the DrVH 72 at the reference position. By displaying the DrVH 71 at the current position and the DrVH 72 at the reference position, the user can estimate the damage to normal tissue at the current position due to radiation at a dose rate below the FLASH effect threshold, compared to the reference position. The DrVH 71 at the current position and the DrVH 72 at the reference position are displayed in different visual modes, such as different line types and colors. A message corresponding to the determination result of the presence or absence of misalignment in step SB2 is displayed in the display area I32. For example, if it is determined that there is misalignment in step SB2, a message indicating the misalignment, such as "Misalignment has occurred," is displayed, as shown in FIG. 14.

[0094] When step SB4 is performed, the processing circuit 51 acquires the normal irradiation volume ratio at the current position and the normal irradiation volume ratio at the reference position (step SB5) by implementing the acquisition function 511. In step SB5, the processing circuit 51 acquires the normal irradiation volume ratio at the current position and the normal irradiation volume ratio at the reference position from the storage device 52 that stores the normal irradiation volume ratios for each of multiple combinations of positional deviation directions and positional deviation amounts.

[0095] When step SB5 is performed, the processing circuit 51, by implementing the determination function 514, determines whether the positional deviation calculated in step SB1 is outside the allowable range (step SB6). In step SB6, the processing circuit 51 determines that the positional deviation is outside the allowable range if the positional deviation amount exceeds a predetermined threshold, and determines that the positional deviation is not outside the allowable range if the positional deviation amount is below the predetermined threshold. The threshold can be set to any value. Furthermore, the threshold may be set to different values ​​depending on the positional deviation direction.

[0096] If it is determined in step SB6 that the positional deviation is outside the allowable range (step SB6: YES), the processing circuit 51 issues a warning by implementing the warning function 515 (step S7). In step SB7, the processing circuit 51 displays a warning screen on the display device 53 in a predetermined layout.

[0097] Fig. 15 is a diagram showing an example of a warning screen I4. The warning screen I4 is displayed on the display device 53. As shown in Fig. 15, the warning screen I4 includes a display area I41 of the DrVH, a first display area I42, a second display area I43, and a third display area I44. The display area I41 and the first display area I42 of the DrVH are similar to the display area I31 and the display area I32 of Fig. 14, respectively.

[0098] As shown in FIG. 15, the second display area I43 displays a message corresponding to the determination result of whether the positional deviation is outside the allowable range in step SB6. For example, if it is determined in step SB6 that the positional deviation is outside the allowable range, a warning message such as "Positional deviation is not allowable" is displayed. The third display area I44 displays a message indicating the direction and amount of correction for the positional deviation. The direction and amount of correction for the positional deviation are calculated based on the direction and amount of positional deviation from the reference position to the current position calculated in step SB1. Specifically, the direction of positional deviation from the current position to the reference position is specified, and the amount of correction is specified as the amount of positional deviation from the current position to the reference position. For example, as shown in FIG. 13, if the positional deviation from the reference position to the current position is 3 cm caudal, the direction of correction is cephalad, and the amount of correction is 3 cm. By displaying the direction and amount of correction in this manner, the user can easily place the patient from the current position to the reference position.

[0099] The correction direction and correction amount are not limited to being displayed as a message on the warning screen I4 as shown in Fig. 15. For example, if a projector is available as the display device 53, the correction direction and correction amount may be projected onto the patient's body surface or the like.

[0100] FIG. 16 is a diagram showing an example of projection of the correction direction and correction amount. As shown in FIG. 16, a patient P is placed on the bed 41 of the radiation therapy apparatus 4. As shown in FIG. 12, the patient P is placed at a current position that is 3 cm caudal to the reference position. In this case, the correction direction and correction amount are, as described above, head direction and 3 cm, respectively. The projector serving as the display device 53 projects a projection image I5 indicating the correction direction and correction amount onto the body surface of the patient P. The projection image I5 is composed of a mark indicating the correction direction and a numerical value indicating the correction amount. Specifically, an arrow indicating the head direction is projected as the mark indicating the correction direction, and a numerical value indicating the correction amount, such as 3 cm, is projected superimposed on the arrow. By projecting the correction direction and correction amount onto the body surface of the patient in this way, the user can grasp the correction direction and correction amount without moving their line of sight to the display.

[0101] When step SB7 is performed, the treatment support processing by the radiation therapy support device 5 is completed. After the treatment support processing, the radiation therapy device 4 performs radiation therapy on the patient.

[0102] 12 is merely an example, and the present invention is not limited to this example, and various modifications are possible. Some modifications will be described below.

[0103] In the above processing example, the processing circuit 51 acquires the DrVH in step SB3 and displays the DrVH in step SB4, but it may also acquire the DVH in step SB3 and display the DVH in step SB4.

[0104] As described above, the radiation therapy support device 5 according to the second embodiment includes a processing circuitry 51. The processing circuitry 51 calculates the positional deviation between the current position of the patient placed on the bed of the radiation therapy device 4 and the reference position. The processing circuitry 51 determines whether the positional deviation is permissible based on a comparison between the volume index value (normal irradiation volume ratio) of a region of the patient's normal tissue corresponding to the current position, which has a predicted dose index value below the FLASH effect threshold, and the reference volume index value. If it is determined that the positional deviation is not permissible, the processing circuitry 51 issues a warning.

[0105] With the above configuration, the processing circuitry 51 determines whether or not the patient's positional shift is acceptable depending on the normal irradiation volume ratio of normal tissue, and therefore, it is possible to evaluate the appropriateness of the patient's positional shift depending on the volume amount at which the FLASH effect on normal tissue can be obtained.

[0106] According to at least one of the embodiments described above, adverse events to normal tissues in radiation therapy can be reduced.

[0107] The term "processor" used in the above description refers to a circuit such as a CPU, a GPU, an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). A processor realizes its functions by reading and executing a program stored in a memory circuit. Note that instead of storing a program in a memory circuit, a program may be directly embedded in the processor circuit. In this case, the processor realizes its functions by reading and executing the program embedded in the circuit. Alternatively, instead of executing a program, a function corresponding to the program may be realized by combining logic circuits. Note that each processor in this embodiment is not limited to being configured as a single circuit, but may be configured as a single processor by combining multiple independent circuits to realize its function. Furthermore, multiple components in FIGS. 1, 2, and 11 may be integrated into a single processor to realize its function.

[0108] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims.

[0109] With respect to the above embodiment, the following supplementary notes are disclosed as one aspect and optional features of the invention.

[0110] (Appendix 1) a setting unit for setting radiation irradiation conditions for a medical image relating to a patient; an acquisition unit that acquires a histogram of radiation dose rates in a predetermined region of the patient based on the irradiation conditions; an evaluation unit that evaluates the irradiation conditions based on the histogram; an output unit that outputs information based on the evaluation result of the irradiation conditions; A radiation therapy planning device comprising:

[0111] (Appendix 2) The evaluation unit may determine whether the irradiation conditions are appropriate based on the histogram.

[0112] (Appendix 3) The evaluation unit may determine whether the irradiation conditions are appropriate based on a comparison between a volume ratio of a first region in the histogram where the FLASH irradiation effect is not obtained or a second region in the histogram where the FLASH irradiation effect is obtained, and a first threshold value. FLASH irradiation is a technique for selectively damaging tumors without damaging normal tissues by irradiating them with radiation at an ultra-high dose rate (e.g., 40 Gy / sec or more) for a short period of time (e.g., 1 sec or less).

[0113] (Appendix 4) The radiation therapy planning apparatus may further include an identifying unit that identifies the first region and the second region in the medical image or the histogram relating to the predetermined region.

[0114] (Appendix 5) The identification unit may identify a penumbra region in the predetermined region as the first region, and identify a region in the predetermined region other than the penumbra region as the second region.

[0115] (Appendix 6) The identification unit may identify the first region and the second region based on at least one of an irradiation depth of radiation in the irradiation region, a radiation absorption characteristic of tissue in the irradiation region, and a penumbra in the irradiation region.

[0116] (Appendix 7) The identifying unit identifies the first region and the second region based on the histogram and a second threshold value related to the dose rate.

[0117] (Appendix 8) The evaluation unit may determine whether the irradiation conditions are appropriate based on a comparison between a predicted dose to tissue in a first region where the irradiation effect of FLASH cannot be obtained and a tolerable dose of the tissue.

[0118] (Appendix 9) The output unit may display information based on the suitability of the irradiation conditions on a display device.

[0119] (Appendix 10) When the irradiation conditions are determined to be inappropriate, the output unit may display information that prompts the user to change the irradiation conditions as information based on the suitability of the irradiation conditions.

[0120] (Appendix 11) The output unit may display the first area and the second area on a display device so that the first area and the second area can be distinguished from each other.

[0121] (Appendix 12) The output unit may display the histogram on a display device so that the first region and the second region are visually distinguishable from each other.

[0122] (Appendix 13) The output unit may attach a mark representing the first threshold to the displayed histogram.

[0123] (Appendix 14) The output unit may display a numerical value representing the volume ratio of the first region and / or the second region on a display device.

[0124] (Appendix 15) setting radiation exposure conditions for medical images relating to a patient; obtaining a histogram of radiation dose rates in a predetermined region of the patient based on the irradiation conditions; evaluating the illumination conditions based on the histogram; outputting information based on the evaluation result of the irradiation conditions; A radiation therapy planning method comprising:

[0125] (Appendix 16) a calculation unit that calculates a positional deviation between a current position of a patient placed on a bed and a reference position; a determination unit that determines whether the positional deviation is allowable based on a comparison between a volume ratio of a region associated with a predicted dose rate below a threshold in the patient's normal tissue corresponding to the current position and a reference value; a notification unit that issues a warning when it is determined that the positional deviation is not allowable; A radiation therapy support device equipped with the above.

[0126] (Appendix 17) The reference value may be a volume fraction of the normal tissue of the patient corresponding to the reference location with a predicted dose rate below the threshold.

[0127] (Appendix 18) The radiation therapy support apparatus may further include an output unit that displays, on a display device, a first histogram of predicted dose rates for the current position and a second histogram of predicted dose rates for the reference position.

[0128] (Appendix 19) a setting unit that sets radiation irradiation conditions; a calculation unit that calculates a volume index value of a region related to a predicted dose index value that is lower than a first threshold value based on the irradiation condition; a determination unit that determines whether the irradiation conditions are acceptable based on the volume index value; A radiation therapy planning device comprising: The irradiation conditions include at least an irradiation field of radiation set in a medical image and an exposure dose index value.

[0129] (Appendix 20) The determination unit may determine that the irradiation conditions are not permissible when the volume index value is greater than a second threshold, and may determine that the irradiation conditions are permissible when the volume index value is less than the second threshold.

[0130] (Appendix 21) The calculation unit may generate a spatial distribution of predicted dose index values ​​for the irradiation field based on the irradiation conditions, generate a frequency distribution of predicted dose index values ​​for the normal tissue based on the spatial distribution, and calculate the volume index value by applying the first threshold to the frequency distribution.

[0131] (Appendix 22) The radiation therapy planning device may further include a region specifying unit that specifies, from the irradiation field, a first irradiation region to be irradiated with penumbra radiation and a second irradiation region to be irradiated with non-penumbra radiation. The calculation unit may generate the spatial distribution by allocating a predicted dose index value reduced by an aperture to the first irradiation region and a predicted dose index value not reduced by the aperture to the second irradiation region.

[0132] (Appendix 23) The radiation therapy planning device may further include a display device that displays the volume index value numerically or graphically.

[0133] (Appendix 24) The radiation therapy planning apparatus may further include a display device that displays the volume index value for the first irradiation region and the volume index value for the second irradiation region as numerical values ​​or graphs.

[0134] (Appendix 25) The radiation therapy planning device may further include a change unit that changes the irradiation conditions in accordance with an instruction from an operator or a predetermined algorithm when the irradiation conditions are determined to be unacceptable. The calculation unit may calculate a changed volume index value based on the changed irradiation conditions. The determination unit may determine whether the changed irradiation conditions are acceptable based on the changed volume index value.

[0135] (Appendix 26) The irradiation conditions may further include the direction of irradiation of the radiation.

[0136] (Appendix 27) The first threshold may have a value at which a therapeutic effect can be obtained by high-dose ultrashort-time irradiation of the normal tissue.

[0137] (Appendix 28) When the irradiation field includes a plurality of normal tissues, the calculation unit may calculate the volume index value for each of the plurality of normal tissues.

[0138] (Appendix 29) The predicted dose index value may be a predicted dose value and / or a predicted dose rate value, and the volume index value may be a volume or a volume fraction.

[0139] (Appendix 30) a calculation unit that calculates a positional deviation between a current position of a patient placed on a bed and a reference position; a determination unit that determines whether the positional deviation is allowable based on a comparison between a volume index value of a region of the patient's normal tissue corresponding to the current position, the region having a predicted dose index value below a threshold, and a reference volume index value; a notification unit that issues a warning when it is determined that the positional deviation is not allowable; A radiation therapy support device equipped with the above.

[0140] (Appendix 31) The reference volume index value may be a volume index value of a region of the normal tissue of the patient corresponding to the reference location with a predicted dose index value below the threshold.

[0141] (Appendix 32) The radiation therapy support apparatus may further include a display device that displays a first frequency distribution of predicted dose index values ​​for the current position and a second frequency distribution of predicted dose index values ​​for the reference position. [Explanation of symbols]

[0142] 1. Radiation therapy system 2 Medical imaging diagnostic equipment 3 Radiation treatment planning device 4 Radiation therapy equipment 5 Radiation therapy support equipment 31 Processing circuit 32 Storage device 33 Display equipment 34 Input Devices 35 Communication equipment 41 berth 51 Processing circuit 52 Storage device 53 Display equipment 54 Input Devices 55 Communication equipment 311 Acquisition Function 312 Condition setting function 313 Area identification function 314 Calculation function 315 Judgment Function 316 Display Control Function 511 Acquisition Function 512 Calculation function 513 Distribution display function 514 Judgment Function 515 Warning Function

Claims

1. a setting unit for setting radiation irradiation conditions for a medical image relating to a patient; an acquisition unit that acquires a histogram of radiation dose rates in a predetermined region of the patient based on the irradiation conditions; an evaluation unit that evaluates the irradiation conditions based on the histogram; an output unit that outputs information based on the evaluation result of the irradiation conditions; Equipped with the evaluation unit determines whether the irradiation conditions are appropriate based on a comparison between a volume ratio of a first region in which the irradiation effect of FLASH is not obtained or a second region in which the irradiation effect of FLASH is obtained in the histogram to the predetermined region and a first threshold value. Radiation treatment planning equipment.

2. The radiation therapy planning apparatus according to claim 1 , further comprising an identifying unit that identifies the first region and the second region in the medical image or the histogram relating to the predetermined region.

3. The radiation therapy planning device according to claim 2 , wherein the specifying unit specifies a penumbra region in the predetermined region as the first region, and specifies a region other than the penumbra region in the predetermined region as the second region.

4. 3. The radiation therapy planning device according to claim 2, wherein the specifying unit specifies the first region and the second region based on at least one of an irradiation depth of radiation in an irradiation region of the predetermined region, a radiation absorption characteristic of tissue in the irradiation region, and a penumbra in the irradiation region.

5. The radiation therapy planning apparatus according to claim 2 , wherein the specifying unit specifies the first region and the second region based on the histogram and a second threshold value related to the dose rate.

6. The radiation therapy planning apparatus according to claim 1 , wherein the output unit displays information based on the suitability of the irradiation conditions on a display device.

7. The radiation therapy planning device according to claim 6 , wherein, when the irradiation conditions are determined to be inappropriate, the output unit displays information prompting a change of the irradiation conditions as information based on the appropriateness of the irradiation conditions.

8. The radiation therapy planning apparatus according to claim 1 , wherein the output unit displays the first region and the second region on a display device so that the first region and the second region can be distinguished from each other.

9. The radiation therapy planning apparatus according to claim 1 , wherein the output unit displays the histogram on a display device so that the first region and the second region are visually distinguishable from each other.

10. The radiation therapy planning apparatus according to claim 9 , wherein the output unit attaches a mark representing the first threshold value to the displayed histogram.

11. The radiation therapy planning apparatus according to claim 1 , wherein the output unit displays a numerical value representing the volume ratio of the first region and / or the second region on a display device.

12. A computer comprising: setting radiation irradiation conditions for a medical image relating to a patient; obtaining a histogram of radiation dose rates in a predetermined region of the patient based on the irradiation conditions; evaluating the irradiation conditions based on the histogram; and outputting information based on the evaluation result of the irradiation conditions, the evaluating step determines whether the irradiation conditions are appropriate based on a comparison between a volume ratio of a first region in the histogram where the FLASH irradiation effect is not obtained or a volume ratio of a second region in the histogram where the FLASH irradiation effect is obtained, and a first threshold value; Radiation treatment planning methods.

Images