JP7114348B2 - Tumor position display device and radiotherapy system - Google Patents

Description

Embodiments of the present invention relate to tumor location display devices and radiation therapy systems.

In the moving body tracking irradiation in radiotherapy, the vicinity of the patient's tumor is imaged by 4-dimensional CT, and the treatment plan is performed considering the movement of the tumor due to respiration. According to this method, it is possible to grasp the movement of the tumor due to respiration, but it is difficult to intuitively grasp the movement amount and movement speed of the tumor. Therefore, the operator performs measurement and the like and empirically determines the breathing control method. In addition, moving body tracking irradiation is so-called ambush irradiation in which radiation is irradiated only when a tumor reaches a fixed position. Therefore, moving body tracking irradiation requires more time to complete treatment than continuous radiation irradiation.

Japanese Patent Publication No. 2004-513735 JP 2009-148336 A JP 2012-213604 A

The problem to be solved by the invention is to support the determination of an appropriate radiotherapy policy corresponding to the movement of individual tumors.

A tumor position display device according to an embodiment includes a specifying unit that specifies a tumor region included in a plurality of three-dimensional medical images related to a plurality of time phases, and pixels included in a movement path of the tumor region over the plurality of time phases. a calculation unit for calculating a parameter indicating the degree of retention of the tumor region in each of the pixels; and a two-dimensional medical image based on at least one three-dimensional medical image among the plurality of three-dimensional medical images, and a display unit for displaying in density or color according to the value of the parameter.

FIG. 1 is a diagram showing the configuration of a radiotherapy system according to this embodiment. FIG. 2 is a diagram showing a typical flow of treatment planning by the radiotherapy system according to this embodiment. FIG. 3 is a diagram showing the specifying process of the tumor area and the movement path area performed by the processing circuit in step S2 of FIG. FIG. 4 is a diagram showing the concept of retention parameters calculated by the processing circuit in step S4 of FIG. FIG. 5 is a diagram showing the concept of the dwell time calculated by the processing circuit in step S4 of FIG. FIG. 6 shows a dwell parameter map generated by the processing circuitry in step S5 of FIG. FIG. 7 is a diagram showing an example of a two-dimensional image on which a staying parameter map is superimposed, which is displayed by the processing circuit in step S5 of FIG. FIG. 8 is a diagram showing a display screen of the movement distance displayed by the processing circuit in step S6 of FIG. FIG. 9 is a diagram showing a tumor position and irradiation mode selection screen displayed by the processing circuit in step S7 of FIG. FIG. 10 is a diagram conceptually showing guidelines for determining the irradiation mode in step S7 of FIG. FIG. 11 is a diagram showing a treatment plan selection screen displayed by the processing circuit of FIG.

A tumor position display device and a radiotherapy system according to this embodiment will be described below with reference to the drawings.

A tumor position display device according to this embodiment is a computer for displaying the position of a patient's tumor for treatment planning in radiotherapy. The tumor position display device according to this embodiment may be a computer dedicated to displaying the position of a tumor, or may be incorporated in a computer for treatment planning (hereinafter referred to as a treatment planning device). , may be incorporated in other devices such as a medical image diagnostic device and a radiotherapy device. Hereinafter, it is assumed that the tumor position display device according to this embodiment is incorporated in a treatment planning device.

FIG. 1 is a diagram showing the configuration of a radiotherapy system 1 according to this embodiment. As shown in FIG. 1, the radiotherapy system 1 includes a medical image diagnostic apparatus 10, a treatment planning apparatus 30, a radiotherapy information management system (OIS: Oncology Information System) 50, a respiratory synchronized irradiation management system 70, and a radiotherapy apparatus 90. have. The medical image diagnostic apparatus 10, the treatment planning apparatus 30, the radiotherapy information management system 50, the respiratory synchronized irradiation management system 70, and the radiotherapy apparatus 90 are communicably connected to each other via a network.

The medical image diagnostic apparatus 10 performs medical imaging on a patient to be treated and generates four-dimensional medical image data used for treatment planning. Four-dimensional medical image data includes multiple three-dimensional medical images (volume data) for multiple time phases. The medical image diagnostic apparatus 10 according to this embodiment can be applied to any modality apparatus capable of generating a four-dimensional medical image. Modality apparatuses applicable to this embodiment include, for example, an X-ray computed tomography apparatus, a magnetic resonance imaging apparatus, a cone beam CT apparatus, a nuclear medicine diagnosis apparatus, and the like. The generated four-dimensional medical image data is transmitted to the treatment planning device 30, for example.

The treatment planning device 30 is a computer that uses four-dimensional medical image data to create a treatment plan for a patient to be treated. As shown in FIG. 1, treatment planning device 30 includes processing circuitry 31 , storage device 33 , display device 35 , input device 37 and communication device 39 . The processing circuit 31, storage device 33, display device 35, input device 37, and communication device 39 are communicably connected via a bus or the like.

The processing circuit 31 includes processors such as a CPU (Central Processing Unit) and GPU (Graphics Processing Unit), and memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory). By executing the programs stored in the memory, the processor performs a tumor region identification function 311, a movement time calculation function 312, a retention parameter calculation function 313, a tumor position setting function 314, an irradiation mode determination function 315, and a treatment planning function. 316 and a display control function 317 are implemented.

In the tumor region identifying function 311 , the processing circuit 31 identifies tumor regions included in a plurality of three-dimensional medical images for a plurality of time phases generated by the medical image diagnostic apparatus 10 . The three-dimensional medical images in which the tumor region is specified may be all three-dimensional medical images related to all time phases generated by the medical image diagnostic apparatus 10. may be a three-dimensional medical image relating to

In the travel time calculation function 312 , the processing circuit 31 calculates the travel time of the tumor region identified by the tumor region identification function 311 over a plurality of time phases.

In the retention parameter calculation function 313, the processing circuit 31 calculates the degree of retention of the tumor region in each pixel included in the movement path of the tumor region identified by the tumor region identification function 311 over a plurality of time phases. Calculate the parameters shown. A parameter indicating the degree of retention is hereinafter referred to as a retention parameter.

In the tumor position setting function 314 , the processing circuit 31 sets the position of the tumor region in a plurality of three-dimensional medical images etc. regarding a plurality of time phases by image processing or according to an operator's instruction via the input device 37 .

In the irradiation mode determination function 315 , the processing circuit 31 automatically determines the radiation mode for radiotherapy according to a predetermined algorithm or according to an operator's instruction via the input device 37 .

In the treatment planning function 316 , the processing circuit 31 creates a treatment plan based on the tumor region at the position set by the tumor position setting function 314 and the irradiation mode determined by the irradiation mode determination function 315 .

The processing circuit 31 in the display control function 317 displays various information on the display device 35 . For example, the processing circuit 31 converts a two-dimensional image based on at least one three-dimensional medical image out of a plurality of three-dimensional medical images with density or color according to the value of the dwell parameter calculated by the dwell parameter calculation function 313. indicate. A two-dimensional image is generated by three-dimensional image processing by the processing circuit 31 . Examples of three-dimensional image processing include volume rendering, surface volume rendering, pixel value projection processing, MPR (Multi-Planer Reconstruction) processing, CPR (Curved MPR) processing, and the like. Also, the processing circuit 31 may display the treatment plan or the like created by the treatment planning function 316 on the display device 35 .

The storage device 33 is a storage device such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or an integrated circuit storage device that stores various information. The storage device 33 stores, for example, a plurality of three-dimensional medical images for a plurality of time phases generated by the medical image diagnostic apparatus 10 . The storage device 33 is compatible with portable storage media such as CDs (Compact Discs), DVDs (Digital Versatile Discs), flash memories, semiconductor memory devices such as RAMs (Random Access Memories), etc., in addition to HDDs and SSDs. It may be a driving device that reads and writes various information between them. The storage device 33 may also be implemented as an external storage device connected to the treatment planning apparatus 30 via a network.

The display device 35 displays various information. For example, the display device 35 displays a two-dimensional image generated by the processing circuit 31, a treatment plan, and the like. For example, the display device 35 may be a liquid crystal display (LCD), a CRT (Cathode Ray Tube) display, an organic EL display (OELD: Organic Electro Luminescence Display), a plasma display, or any other display. It is possible.

The input device 37 receives various commands from the operator. A keyboard, a mouse, various switches, and the like can be used as the input device 37 . The input device 37 supplies an operation signal corresponding to the received command to the processing circuit 31 via the bus.

The communication device 39 communicates with the medical image diagnostic apparatus 10, the treatment planning apparatus 30, the radiotherapy information management system 50, the respiratory synchronized irradiation management system 70, and the radiotherapy apparatus 90, which constitute the radiotherapy system 1, via a wired or wireless connection (not shown). perform data communication between

The radiotherapy information management system 50 is a computer system that manages information on radiotherapy in cooperation with the medical image diagnostic apparatus 10, the treatment planning apparatus 30, the respiratory synchronized irradiation management system 70, the radiotherapy apparatus 90, and the like. The radiotherapy information management system 50 comprises an input device, a display, a communication device, and a storage device that a general-purpose computer or workstation has. For example, the radiotherapy information management system 50 manages treatment plans created by the treatment planning device 30 . The radiotherapy information management system 50 supplies the irradiation conditions and the like included in the treatment plan to the respiratory synchronized irradiation management system 70 and the radiotherapy apparatus 90 .

The respiratory synchronized irradiation management system 70 measures the respiratory motion of a patient placed on a treatment bed in a radiation therapy room during radiation therapy before or during radiation irradiation. For example, the respiration-gated irradiation management system 70 generates a respiration waveform indicating changes in the patient's respiration level using a mechanical or optical respiration sensor, and monitors the patient's respiration level. If the respiration level is within a predetermined threshold range, respiration-gated irradiation management system 70 provides a radiation irradiation instruction signal to radiation therapy apparatus 90 .

The radiotherapy apparatus 90 is an apparatus for the purpose of radiotherapy, and treats the patient by irradiating the patient with radiation according to the treatment plan created by the treatment planning apparatus 30 . The radiotherapy apparatus 90 has a treatment platform and a treatment bed provided in the treatment room. The treatment platform supports the irradiation head part rotatably around the rotation axis. The irradiation head unit irradiates radiation according to the irradiation conditions and the like supplied from the radiotherapy information management system 50 . Specifically, the irradiation head unit forms an irradiation field with a multi-divided diaphragm (multi-leaf collimator), and suppresses irradiation of normal tissues by the irradiation field. By irradiating the treatment area with radiation, the treatment area disappears or shrinks. In the case of respiratory-gated irradiation, the radiotherapy apparatus 90 irradiates radiation only when receiving a radiation irradiation instruction signal from the respiratory-gated irradiation management system 70 . As a result, radiation exposure to normal tissue can be reduced even when the tumor moves greatly due to respiratory motion or the like.

An operation example of treatment planning by the radiotherapy system 1 according to this embodiment will be described below.

FIG. 2 is a diagram showing a typical flow of treatment planning by the radiotherapy system 1 according to this embodiment. As shown in FIG. 2, first, the medical image diagnostic apparatus 10 performs medical imaging on a patient to be treated to generate four-dimensional medical image data (step S1). In step S1, the medical image diagnostic apparatus 10 repeats medical imaging for a certain period of time to generate a plurality of three-dimensional medical images related to a plurality of time phases as four-dimensional medical image data. It is assumed that the treatment target according to this embodiment is a tumor whose position changes according to the patient's breathing. Such tumors include, for example, cancers originating in tissues of the chest and abdomen. In order to grasp the patient's respiratory phase during medical imaging for each three-dimensional image, information relating to the respiratory phase is associated with each three-dimensional image. The information related to the respiratory phase may be the numerical value or name of the respiratory phase, or the numerical value of the height of the patient's chest or abdomen (hereinafter referred to as respiratory level). In one respiratory cycle, the time phase with the lowest respiration level is called maximum expiration, and the time phase with the highest respiration level is called maximum inspiration. The numerical value of the respiratory phase may be, for example, the ratio of the time from the reference time phase to the time of one respiratory cycle, or the time from the reference time phase. The name of the respiratory phase is the time of maximum expiration and the time of maximum inspiration described above.

When step S1 is performed, the processing circuit 31 of the treatment planning device 30 executes the tumor area specifying function 311 (step S2). In step SS2, the processing circuit 31 identifies the tumor region and the movement path region for the three-dimensional medical images generated by the medical image diagnostic apparatus 10 during a specific period. The specific period is set to a period including at least from the time of maximum expiration to the time of maximum inspiration or from the time of maximum inspiration to the time of maximum expiration. In the following embodiments, the specific period shall be set to one respiratory cycle. A respiratory cycle is defined as the period between any particular adjacent respiratory phases. Typically, one respiratory cycle is defined as the period between adjacent times of maximum expiration or the period between adjacent times of maximum inspiration.

FIG. 3 is a diagram showing the specifying process of the tumor area and the movement path area performed by the processing circuit 31 in step S2. As shown in FIG. 3, one respiratory cycle includes, for example, a maximum expiration time Te1, a maximum inspiration time Ta following the maximum expiration time Te1, and a maximum expiration time Te2 following the maximum inspiration time Ta. The processing circuit 31 identifies the tumor region included in the three-dimensional medical image for each time phase from the time of maximum expiration Te1 to the time of maximum expiration Te2. The processing circuit 31 may extract the tumor region by arbitrary image processing such as threshold processing, segment processing, machine learning, etc., or may manually specify the tumor region according to the user's instruction via the input device 37. good. For example, the tumor region Rte1 is specified for the three-dimensional medical image Vte1 at the time of maximum expiration Te1, the tumor region Rta is specified for the three-dimensional medical image Vta at the time Te1 for maximum expiration, and the tumor region Rte2 is specified for the three-dimensional medical image Vte2 at the time Te2 for maximum expiration. be done. As shown in FIG. 3, the position of the tumor region periodically changes in the three-dimensional medical image VO due to patient's respiratory motion during medical imaging.

When the tumor region is specified, the processing circuit 31 calculates the sum region of the tumor regions in a plurality of time phases forming one respiratory cycle. For example, a sum area of a plurality of tumor regions is calculated for a plurality of time phases included from the time of maximum exhalation Te1 to the time of maximum exhalation Te2. The calculated sum area is presumed to be the path along which the tumor area moves from Te1 at the time of maximum expiration to Te2 at the time of maximum expiration. The calculated sum area is set as the movement route area Rtr.

When step S2 is performed, the processing circuit 31 executes the travel time calculation function 312 (step S3). In step S3, the processing circuit 31 calculates the movement time of the tumor region in one respiratory cycle. The migration time according to this embodiment is defined as the length of the period during which the tumor region is migrating. In other words, the travel time according to the present embodiment is the travel time of the tumor in consideration of the organ migration in the human body's biological activity such as respiratory braking. For example, if the time from maximum expiration to maximum inspiration is 1.2 seconds, and the time from maximum inspiration to maximum expiration is 2.4 seconds, the movement time of the tumor region in one respiratory cycle is 3.0 seconds. 6 seconds. If the tumor region is constantly moving, the migration time in one respiratory cycle is equal to the length of one respiratory cycle. The travel time of the tumor region in one respiratory cycle is also called one cycle respiratory time. The time from maximum expiration to maximum inspiration and the time from maximum inspiration to maximum expiration are calculated based on time information associated with maximum expiration and time information associated with maximum inspiration. Good luck.

When step S3 is performed, the processing circuit 31 executes the stay parameter calculation function 313 (step S4). In step S4, the processing circuit 31 calculates the residence parameter of the tumor region in one respiratory cycle. A stay parameter is calculated for each pixel included in the moving path area. The retention parameter is a parameter that indicates the degree of retention of the tumor region in each pixel included in the movement path region. Pixels included in the movement path area are hereinafter referred to as movement path pixels. The retention parameters include the number of frames in which a tumor region exists in each moving path pixel (hereinafter referred to as the number of retention frames), the number of retention frames per cycle breathing time, and the number of retention frames per respiratory cycle for one cycle breathing time. ratio (hereinafter referred to as retention ratio), product of retention ratio and 1-cycle respiration time (hereinafter referred to as retention time), ratio of retention ratio to 1-cycle respiration time (hereinafter referred to as retention ratio), tumor An example is the movement speed of the region. A frame corresponds to the time phase of each three-dimensional medical image. The frame rate is defined by the number of time phases included in a unit time, in other words, the number of three-dimensional medical images.

FIG. 4 is a diagram showing the concept of the stay parameter calculated by the processing circuit 31 in step S4. As shown in FIG. 4, the tumor region periodically moves along with respiratory motion in the three-dimensional medical image VO. Here, attention is focused on the movement path pixel Vx included in the movement path area. The processing circuit 31 determines whether or not a tumor region is included in the movement path pixel Vx for each of a plurality of time phases (frames) that constitute one respiratory cycle. If the tumor area is included in the movement path pixel Vx, the time phase (frame) is "stayed", and if the tumor area is not included in the movement path pixel Vx, the time phase (frame) is "no stay". is determined. For example, as shown in FIG. 4, the tumor region Rte1 at the time of maximum expiration is not included in the movement path pixels Vx, so "no retention" at the time of maximum expiration, and the tumor region Rta at the time of maximum inspiration is included in the movement path pixels Vx. Therefore, "no retention" is determined for the time of maximum inspiration, and "with retention" is determined for the intermediate time phase because the tumor region Rtm for the intermediate time phase between maximum expiration and maximum inspiration is included in the movement path pixel Vx.

For example, it is assumed that the breathing time for one cycle consisting of maximum expiration→maximum inspiration→maximum expiration is 3.6 seconds, and the imaging frame rate in four-dimensional CT is 15 fps. In this case, 3.6×15=54 tumor regions are extracted in one respiratory cycle consisting of maximum expiration→maximum inspiration→maximum expiration. That is, the number of time phases (number of frames) in one respiratory cycle is 54. The processing circuit 31 counts the number of time phases (the number of frames) determined to be "with stay" for each movement path pixel as the number of stay frames. For example, in one respiratory cycle, when the tumor region is determined to be “stayed” in 27 frames in a certain movement path pixel, the number of retained frames is calculated as 27. The processing circuit 31 calculates a staying ratio based on the number of staying frames and one cycle breathing time. Specifically, the processing circuit 31 calculates the staying ratio by dividing the number of staying frames by one cycle breathing time. For example, if the number of dwell frames is 27 and the number of frames in one respiratory cycle is 54, the dwell ratio is calculated as 27/54=0.5. Processing circuitry 31 calculates the residence time based on the residence ratio and the one-cycle breathing time. Specifically, the processing circuitry 31 calculates the residence time by multiplying the one-cycle breathing time by the residence ratio. For example, if the dwell ratio is 0.5 and the one-cycle breath time is 3.6 seconds, the dwell time is calculated as 0.5 x 3.6 = 1.8 seconds.

FIG. 5 is a diagram showing the concept of the residence time calculated by the processing circuit 31 in step S4. As shown in FIG. 5, the processing circuit 31 calculates the residence time for each movement route pixel Vx that forms the movement route region Rtr. For example, the residence time of the movement path pixel Vx1 is 1.8 seconds, the residence time of the movement path pixel Vx2 is 1.7 seconds, and so on, for all the movement path pixels Vx.

When the tumor area does not move at all regardless of the patient's breathing, the 1 cycle breathing time is 3.6 seconds, the number of frames in 1 breathing cycle is 54, and all frames are judged to be "with retention", the retention ratio is 54/54=1.0, residence time is 3.6×1.0=3.6 seconds.

Note that the processing circuit 31 may calculate, as the residence parameter, a residence ratio, which is a ratio of the residence ratio to one cycle breathing time. For example, if the one-cycle breath time is 3.6 seconds and the dwell ratio is 0.5, then the dwell ratio is 0.5/3.6=0.14. The processing circuitry 31 may calculate the moving speed of the tumor area as the residence parameter. For example, the moving speed of the tumor area is defined by the number of pixels moved by the tumor area per unit time.

When step S4 is performed, the processing circuit 31 executes the display control function 317 (step S5). In step S5, the processing circuit 31 performs weighted display according to the stay parameter. Specifically, the processing circuit 31 first performs three-dimensional image processing on at least one three-dimensional medical image among a plurality of three-dimensional images related to a plurality of time phases over one respiratory cycle to generate a two-dimensional image. For example, a volume rendering image may be generated by performing volume rendering processing on a three-dimensional medical image of a specific time phase, or a cross-sectional image of an arbitrary cross-section may be generated by performing MPR processing. Further, the processing circuit 31 may generate an averaged image of three-dimensional medical images for a plurality of time phases, and generate a volume rendering image or a cross-sectional image based on the generated averaged image.

The processing circuitry 31 also generates a map (hereinafter referred to as a stay parameter map) representing the spatial distribution of the stay parameters calculated in step S4. The stay parameter map is generated by assigning a density according to the value of the stay parameter to each movement path pixel constituting the map. Note that the color of the movement path pixels may be set to any color such as white, black, red, or blue.

FIG. 6 is a diagram showing the stay parameter map Mtr generated by the processing circuit 31 in step S5 of FIG. The stay parameter map Mtr shown in FIG. 6 is a map in which densities corresponding to the values of the stay parameters are assigned to pixels. In FIG. 6, each pixel of the stay parameter map Mtr is assigned a gray density, ie, a gray level, according to the stay parameter value. As shown in FIG. 6, the tumor region Rt periodically moves between the time of maximum expiration and the time of maximum inspiration. Typically, the tumor region Rt tends to remain temporarily during maximum expiration and maximum inspiration. That is, the residence parameters (eg, residence time and residence ratio) take relatively large values in the existence range of the tumor region Rt at maximum expiration and the tumor region Rt at maximum inspiration. Therefore, the retention parameter map Mtr has a density distribution in which the density increases toward both ends and decreases toward the center. The types of retention parameters for which the retention parameter map Mtr is to be generated can be arbitrarily set via the input device 37 or the like from among the number of retention frames, retention ratio, retention time, retention ratio ratio, and tumor movement speed. be.

FIG. 7 is a diagram showing an example of the two-dimensional image I1 on which the staying parameter map Mtr is superimposed, displayed by the processing circuit 31 in step S5 of FIG. As shown in FIG. 7, the two-dimensional image I1 is a morphological image that depicts the internal structure RP of the patient. The processing circuit 31 aligns and superimposes the stay parameter map Mtr on the two-dimensional image I1 and displays it on the display device 35 . As a result, the stay parameter is weighted and displayed. For example, the staying parameter map Mtr is displayed as an overlay of the two-dimensional image I1. The staying parameter map Mtr is displayed semi-transparently so that the superimposed two-dimensional image I1 can also be seen. By observing the two-dimensional image I1 on which the retention parameter map Mtr is superimposed, the user can grasp the movement range of the tumor in the patient's body and the degree of tumor retention within the movement range.

When step S5 is performed, the processing circuit 31 executes the display control function 317 (step S6). In step S6, the processing circuit 31 displays the movement distance of the tumor region in one respiratory cycle on the display device 35. FIG.

FIG. 8 is a diagram showing the display screen SC1 of the movement distance displayed by the processing circuit 31 in step S6. As shown in FIG. 8, the display screen SC1 includes a two-dimensional image I2 on which the stay parameter map Mtr is superimposed and a display field I3. The display field I3 displays the moving distance of the tumor region in one respiratory cycle. The travel distance is defined by the distance between the tumor area at maximum exhalation and the tumor area at maximum inspiration. For example, the processing circuit 31 calculates the distance between both ends of the moving path area specified in step S2 in the moving direction as the moving distance. The distance may be calculated as the number of pixels, or may be calculated as the actual distance expressed in units such as millimeters (mm). As shown in FIG. 8, the processing circuit 31 displays a two-dimensional image I2 on which the retention parameter map Mtr is superimposed and a display field I3 for the moving distance of the tumor area side by side. For example, when the moving distance is calculated to be 15 mm, it is displayed as "tumor moving distance: 15 mm". Knowing the movement distance of the tumor enables the user to better understand the movement range of the tumor within the patient's body and the degree of tumor retention within the movement range.

When step S6 is performed, the processing circuit 31 executes the tumor position setting function 314 and the irradiation mode determination function 315 (step S7). In step S7, the processing circuitry 31 waits for selection of the tumor position and irradiation mode.

FIG. 9 is a diagram showing a tumor position and irradiation mode selection screen SC2 displayed by the processing circuit 31 in step S7. As shown in FIG. 9, the selection screen SC2 includes a two-dimensional image I4 on which the retention parameter map Mtr is superimposed, a display field I5 displaying the movement distance of the tumor region in one respiratory cycle, and an irradiation mode selection field I6. including. A confirmation button B1 for confirming the tumor position and the irradiation mode is also displayed on the selection screen SC2. The user designates the position Pt of the tumor region used for treatment planning in the two-dimensional image I4 via the input device 37 . The processing circuitry 31 sets the specified position Pt as the tumor position. According to this embodiment, since the retention parameter map Mtr can be observed, it is possible to specify the tumor position by more accurately considering respiratory motion. For example, the tumor position Pt may be designated so as to surround the entire retention parameter map Mtr, or only a portion of the retention parameter map Mtr (portion where the degree of retention is locally high) is designated as the tumor position Pt. Also good.

As shown in FIG. 9, the selection field I6 displays irradiation mode specification buttons Br1, Br2, and Br3. The irradiation mode according to the present embodiment refers to a radiation irradiation method in radiotherapy. Irradiation modes include, for example, respiratory gating, intensity modulation, and normal irradiation. “Respiratory gating” is an irradiation mode in which radiation is limited to a specific respiratory phase so that radiation is limited to when the tumor is located in a specific area. "Intensity Modulation" is a non-respiratory-gated method with a spatially non-uniform dose distribution. In "intensity modulation", radiation is always emitted while spatially modulating the intensity of the radiation within the irradiation range of the radiation. "Normal irradiation" is a non-respiratory-gated technique with a spatially uniform dose distribution. In the "normal irradiation", the radiation is always irradiated without spatially modulating the intensity of the radiation within the irradiation range of the radiation. In FIG. 9, the designation button Br1 corresponding to respiratory gating is selected. The processing circuit 31 sets the irradiation mode corresponding to the selected designation button as the irradiation mode for radiotherapy.

FIG. 10 is a diagram conceptually showing guidelines for determining an irradiation mode. As shown in FIG. 10, the irradiation mode is determined from both the residence parameter map and the movement distance. For example, as shown in the left end of FIG. 10, when the movement distance of the tumor region is relatively long (12 mm) and the value of the retention parameter is biased in the retention parameter map (that is, there is a bias in density or color), Respiratory gating is selected as the irradiation mode. As shown in the center of FIG. 10, when the movement distance of the tumor region is relatively short (3 mm) and there is no bias in the retention parameter values in the retention parameter map (that is, there is no bias in density or color), the irradiation mode is selected for normal irradiation. As shown in the right end of FIG. 10, when the moving distance of the tumor region is relatively short (7 mm) and the retention parameter values are biased in the retention parameter map, intensity modulation is selected as the irradiation mode.

When the user presses the confirmation button B1 via the input device 37, the processing circuitry 31 confirms the selected irradiation mode and tumor position.

Note that the processing circuitry 31 may automatically determine an irradiation mode in radiotherapy based on the residence parameter map and the movement distance. Specifically, the processing circuit 31 determines whether or not the stay parameter values are biased in the stay parameter map. The presence or absence of bias is determined, for example, by the magnitude relationship between the difference between the stay parameter value at the end of the stay parameter map and the stay parameter value at the center, and the first threshold. The processing circuit 31 determines that there is bias when the difference is greater than the first threshold, and determines that there is no bias when the difference is less than the first threshold. Processing circuitry 31 then compares the distance traveled against a second threshold. The processing circuit 31 determines that the moving distance is relatively long when the moving distance is longer than the second threshold, and determines that the moving distance is relatively short when the moving distance is shorter than the second threshold. As shown in the left end of FIG. 10, when it is determined that there is an imbalance and the movement distance is relatively long, the processing circuit 31 selects "respiratory gating" as the irradiation mode. As shown in the center of FIG. 10, when it is determined that there is no bias and the moving distance is relatively short, the processing circuit 31 selects "normal irradiation" as the irradiation mode. As shown in the right end of FIG. 10, when it is determined that there is an imbalance and the moving distance is relatively short, the processing circuit 31 selects "intensity modulation" as the irradiation mode. As described above, according to the present embodiment, it is possible to objectively adopt an irradiation mode based on the tumor movement distance and the tumor retention parameter.

Note that the processing circuit 31 can also automatically set the tumor position based on the irradiation mode and retention parameter map. For example, if the irradiation target is "respiratory-gated," a region in the retention parameter map in which the retention parameter value is higher than the third threshold is set as the tumor position. As a result, it is possible to carry out a treatment plan targeting a portion where the degree of retention is relatively high. Note that the third threshold can be set to any value via the input device 37 . When the irradiation targets are "normal irradiation" and "intensity modulation", the entire area of the residence parameter map is set to the tumor position. This allows treatment planning to target the entire tumor migration region. Note that an area expanded by a margin range from the entire area of the retention parameter map may be set as the tumor position in consideration of variations in respiratory motion and the like.

If it is determined in step S7 that the tumor position and irradiation mode have been selected (step S7: YES), the processing circuitry 31 executes the treatment planning function 316 (step S8). In step S8, the processing circuit 31 utilizes at least one three-dimensional medical image among a plurality of three-dimensional medical images related to a plurality of time phases included in one respiratory cycle to determine the tumor position and irradiation mode selected in step S7. create a treatment plan based on Spatial dose distribution and the like are calculated as the treatment plan. The processing circuit 31 uses the tumor position selected in step S7 as a target region and generates a spatial dose distribution dependent on the irradiation mode selected in step S7. The created treatment plan is displayed on the display device 35 by the processing circuit 31 .

This completes the description of the operation example of the treatment planning by the radiotherapy system 1 according to the present embodiment.

The flow of the treatment plan described above is an example, and various modifications are possible. For example, the display of the movement distance in step S6 can be omitted if not necessary. Further, the order of identifying the tumor region and the moving route region in step S2 and calculating the moving time in step S3 may be reversed.

The display mode of the stay parameter map is also not limited to the above example. In the above example, the stay parameter map expresses the stay parameter values with arbitrary color densities. However, the stay parameter map may be a color map that expresses stay parameter values with different colors. For example, the staying parameter value is divided into a plurality of divisions according to the size, and a color is assigned to each division. For example, if it is divided into 5 segments, the 1st segment with the highest value is red, the 2nd segment is orange, the 3rd segment is green, the 4th segment is blue, and the 5th segment is purple. assigned. In this way, by expressing the retention parameter value by the type of color, it becomes possible to grasp the degree of retention more quickly and clearly. Note that the color density may be the same in each segment, or may be changed according to the retention parameter value.

The display mode of the two-dimensional image is also not limited to the above example. The processing circuit 31 may superimpose the movement of the tumor region over a plurality of time phases on the two-dimensional image and display it as an animation. Specifically, the processing circuitry 31 displays a picture representing the tumor superimposed on the tumor region depicted in the two-dimensional image. Since the tumor area related to the animation display has higher visibility than the tumor area of the two-dimensional image, it is possible to clearly grasp the movement of the tumor area over multiple time phases and the position of the tumor area for each time phase. can. Note that the processing circuit 31 may superimpose the movement of the tumor region over a plurality of time phases on the retention parameter map and display it as an animation.

In the above example, it is assumed that the treatment plan is created based on the tumor location and tumor mode selected in step S7. However, this embodiment is not limited to this. Since radiotherapy is performed over a number of days, it is assumed that the patient's breathing pattern will change from the day the treatment was started. The processing circuit 31 according to this embodiment can create a treatment plan for each of a plurality of different combinations of the moving distance of the tumor region, the retention parameter value, and the irradiation mode. A treatment plan is created for each of the plurality of combinations, as described above, using at least one three-dimensional medical image among the plurality of three-dimensional medical images relating to the plurality of time phases included in one respiratory cycle. The processing circuit 31 displays the treatment plan created for each of the plurality of combinations on the display device 35 .

FIG. 11 shows a treatment plan selection screen SC3 displayed by the processing circuit 31. As shown in FIG. As shown in FIG. 11, the selection screen SC3 displays treatment plans DD created for each of a plurality of combinations of different tumor region moving distances and irradiation modes. A dose distribution image in which a spatial dose distribution is superimposed on a CT image is displayed as the treatment plan DD. For example, the dose distribution image I7 for the irradiation target “normal irradiation” and the movement distance “3 mm”, the dose distribution image I8 for the irradiation target “intensity modulation” and the movement distance “7 mm”, the irradiation target “respiratory synchronization” and the movement distance “ 15 mm" is displayed. An instruction button Br for instructing selection of the corresponding treatment plan is displayed near each dose distribution image. For example, as shown in FIG. 11, below the dose distribution image I7, an instruction button Br4 for instructing selection of a treatment plan corresponding to the dose distribution image I7 is displayed. When an arbitrary instruction button Br is pressed and the confirmation button B2 is pressed, the processing circuit 31 adopts the treatment plan corresponding to the pressed instruction button. For example, the user observes changes in spatial dose distribution due to changes in moving distance for each irradiation mode. Then, the user selects an irradiation mode with a small spatial dose distribution, and selects a treatment plan for the selected irradiation mode and for the residence parameter value calculated in step S4 and the movement distance calculated in step S6 or its vicinity. . This allows the adoption of a robust treatment plan that is robust against changes in breathing patterns.

In FIG. 11, a dose distribution image is created and displayed for each combination of moving distance and irradiation mode. A dose distribution image may be created and displayed for each combination of , for each combination of moving distance, retention parameter value, and irradiation mode, and for each combination of retention parameter value and irradiation mode.

Thus, the processing circuit 31 according to this embodiment can create and display treatment plans for each of a plurality of combinations of at least one of the movement distance, the dwell parameter value, and the irradiation mode. As a result, the user can adopt a treatment plan that is resistant to changes in breathing patterns while taking into consideration the moving distance and degree of retention of the tumor region due to respiratory motion.

As described above, the tumor position display device 30 according to this embodiment has the processing circuit 31 capable of executing at least the tumor region specifying function 311 , the retention parameter calculation function 313 and the display control function 317 . The processing circuitry 31 identifies tumor regions included in multiple three-dimensional medical images for multiple time phases. The processing circuit 31 calculates a retention parameter indicating the degree of retention of the tumor region in each movement path pixel for each movement path pixel included in the movement path of the tumor area over a plurality of time phases. The processing circuit 31 displays a two-dimensional medical image based on at least one three-dimensional medical image among the plurality of three-dimensional medical images on the display device 35 in density or color according to the value of the retention parameter.

With the above configuration, the tumor position display device 30 according to the present embodiment can present the degree and mode of tumor movement associated with respiratory movement to the user by performing the weighted display of the retention parameter. By observing the weighted display, the user can accurately grasp the movements of individual tumors accompanying respiratory movements. This allows the user to select an appropriate irradiation mode corresponding to the movement of individual tumors accompanying respiratory motion, and thus to determine an appropriate radiotherapy planning policy.

According to at least one embodiment described above, it is possible to support the determination of an appropriate radiotherapy planning policy corresponding to individual tumor movements.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

1 Radiation therapy system 10 Medical image diagnosis device 30 Tumor position display device (treatment planning device)
31 processing circuit 33 storage device 35 display device 37 input device 39 communication device 50 radiotherapy information management system (OIS: Oncology Information System)
70 Respiratory gated irradiation management system 90 Radiotherapy apparatus 311 Tumor region identification function 312 Moving time calculation function 313 Retention parameter calculation function 314 Tumor position setting function 315 Irradiation mode determination function 316 Treatment planning function 317 Display control function

Claims (9)

an identifying unit that identifies a tumor region included in a plurality of three-dimensional medical images related to a plurality of respiratory phases included in at least one respiratory cycle of a patient to be treated ;
a calculation unit that calculates, for each of the pixels included in the moving path of the tumor region over the plurality of respiratory phases, a parameter indicating the degree of retention of the tumor region in each of the pixels;
superimposing a map representing the spatial distribution of the parameter and having a density or color corresponding to the value of the parameter on a two-dimensional medical image based on at least one three-dimensional medical image among the plurality of three-dimensional medical images; a display unit for displaying;
A tumor position display device comprising: The calculation unit uses, as the parameters, the number of frames in which the tumor region exists in each of the pixels, the number of frames in which the tumor region exists in each of the pixels in the at least one respiratory cycle, and the number of frames relative to the movement time of the tumor region. 2. The tumor position according to claim 1, wherein a retention ratio that is a ratio of numbers, a retention time that is a product of the retention ratio and the migration time, a ratio of the retention ratio to the migration time, or a migration speed of the tumor area is calculated. display device. 2. The tumor position indicating device according to claim 1, wherein said plurality of respiratory phases includes a maximum expiration breathing phase and a maximum inspiration breathing phase. 2. The tumor position display device according to claim 1, further comprising a setting unit for setting a tumor position used for creating a treatment plan based on said map in said two-dimensional medical image. The calculation unit calculates a moving distance of the tumor region over the plurality of respiratory phases,
the display unit displays the two-dimensional medical image and the movement distance of the tumor region;
The tumor position display device according to claim 1. Further comprising a determination unit that determines a radiation irradiation mode in radiation therapy based on the movement distance and the map ,
The display unit displays the irradiation mode,
The tumor position display device according to claim 5 . 7. The tumor position display device according to claim 6 , wherein said irradiation modes include respiratory gating, non-respiratory gating with a spatially uniform dose distribution, and non-respiratory gating with a spatially non-uniform dose distribution. further comprising a treatment planning unit that prepares a treatment plan for each of a plurality of different combinations of the moving distance of the tumor region, the parameter, and the radiation irradiation mode in radiotherapy;
the display unit displays the treatment plan for each of the plurality of combinations;
The tumor position display device according to claim 1. an imaging unit that performs medical imaging on a patient to be treated and generates a plurality of three-dimensional medical images related to a plurality of respiratory phases included in at least one respiratory cycle ;
an identifying unit that identifies a tumor region included in the plurality of three-dimensional medical images;
a calculation unit that calculates, for each of the pixels included in the moving path of the tumor region over the plurality of respiratory phases, a parameter indicating the degree of retention of the tumor region in each of the pixels;
superimposing a map representing the spatial distribution of the parameter and having a density or color corresponding to the value of the parameter on a two-dimensional medical image based on at least one three-dimensional medical image among the plurality of three-dimensional medical images; a display unit for displaying;
A radiotherapy system comprising:

Images