JP2023114192A - Radiation therapy planning device - Google Patents

Abstract

To provide an appropriate radiation therapy plan while suppressing damage to a normal tissue region.SOLUTION: A radiation therapy planning device 3 includes: a region extraction unit 111 for extracting a tumor region and a normal tissue region included in a medical image; an irradiation plan creation unit 112 for acquiring reference information indicating a durable dose of the normal tissue region according to a lethal dose of the tumor region, a threshold of a dose rate at which the normal tissue region acquires an irradiation effect related to FLASH (ultra-high dose rate short time radiation irradiation), and a dose rate of a radioactive ray radiated to the normal tissue region, and creating an irradiation plan for the radioactive ray radiated to the tumor region and the normal tissue region on the basis of the reference information; and an information output unit 113 for outputting information based on the created irradiation plan.SELECTED DRAWING: Figure 2

Description

The embodiments disclosed in the specification and drawings relate to radiation therapy planning apparatus.

In recent years, a radiation treatment method called FLASH has attracted attention. FLASH irradiates radiation at a dose rate (e.g., 40 Gy/s or more) that is much higher than the dose rate (e.g., about 0.03 Gy/s) in general radiotherapy in a short time (e.g., 1 second or less). treatment of the tumor site.

FLASH tends to protect (do not damage) normal tissue sites even when irradiated with a dose of radiation equivalent to the dose at which normal tissue sites are damaged in general radiotherapy. In other words, FLASH tends to protect normal tissue sites while maintaining therapeutic effects on tumor sites, and is expected to reduce side effects of radiotherapy.

Japanese Patent Publication No. 2004-532671 JP 2011-78750 A Japanese Patent Application Publication No. 2013-524956

One of the problems addressed by the embodiments disclosed in the specification and drawings is to limit damage to normal tissue sites and provide adequate radiation treatment planning. However, the problems to be solved by the embodiments disclosed in this specification and drawings are not limited to the above problems. A problem corresponding to each effect of each configuration shown in the embodiments described later can be positioned as another problem.

A radiotherapy planning apparatus according to an embodiment includes a site extraction unit that extracts a tumor site and a normal tissue site included in a medical image, a lethal dose of the tumor site, and a FLASH (ultra-high dose rate short-time radiation dose) for the normal tissue site. irradiation), and the reference information representing the tolerable dose of the normal tissue part according to the dose rate of the radiation irradiated to the normal tissue part, and the obtained reference information and an information output unit for outputting information based on the generated irradiation plan.

1 is a block diagram showing the configuration of a radiotherapy system according to an embodiment; FIG. 2 is a block diagram showing the configuration of the radiotherapy planning apparatus shown in FIG. 1; FIG. 3 is a diagram showing the configuration of a lethal dose table stored in the storage unit shown in FIG. 2; FIG. (a) is a diagram showing a configuration of a tolerable dose table (FLASH) stored in a storage unit shown in FIG. 2. FIG. (b) is a diagram showing a configuration of a tolerable dose table (general radiotherapy) stored in the storage unit shown in FIG. 2; It is the figure which showed radiation attenuation rate data typically. 3 is a flowchart showing processing executed by the radiotherapy planning apparatus shown in FIG. 2; (a) is a schematic diagram showing a tumor site included in a medical image. (b) is a schematic diagram showing an irradiation path of radiation. 2 is a block diagram showing the configuration of a radiotherapy planning apparatus according to Embodiment 2; FIG. 9 is a flowchart showing processing executed by the radiotherapy planning apparatus shown in FIG. 8;

(Embodiment 1)
The configuration of a radiotherapy system according to one embodiment will be described below with reference to the drawings. As shown in FIG. 1 , the radiation therapy system 1 has a medical image diagnostic device 2 , a radiation therapy planning device 3 and a radiation therapy device 4 . The medical image diagnostic apparatus 2, radiotherapy planning apparatus 3, and radiotherapy apparatus 4 are communicably connected to each other via a network.

The medical image diagnostic apparatus 2 generates medical images to be used for radiation therapy planning for a patient to be subjected to radiation therapy. The medical image may be a two-dimensional image composed of two-dimensionally arranged pixels, or a three-dimensional image composed of three-dimensionally arranged voxels. The medical image diagnostic device 2 may be any modality device capable of generating medical images. Modality devices include, for example, X-ray computed tomography (CT), magnetic resonance imaging (MRI), cone beam CT, nuclear medicine diagnosis (PET: positron emission tomography, SPECT: Single Photon Emission Computed Tomography) and the like.

The radiotherapy apparatus 4 irradiates the patient with radiation according to the radiotherapy plan created by the radiotherapy planning apparatus 3 to treat the patient. The radiotherapy apparatus 4 is installed in a treatment room and has a treatment platform and a treatment bed. The treatment table moves the tabletop so that the treatment site (tumor site) of the patient substantially coincides with the isocenter. The treatment platform supports the irradiation head part rotatably around the rotation axis. The irradiation head unit irradiates radiation according to a treatment plan. Specifically, the irradiation head unit forms an irradiation range of radiation with a multi-split diaphragm (multi-leaf collimator).

The radiotherapy planning apparatus 3 uses the medical images generated by the medical image diagnostic apparatus 2 to create a radiotherapy plan. The radiotherapy planning device 3 provides the radiotherapy device 4 with the created radiotherapy plan. The radiation therapy planning apparatus 3 may store the created radiation therapy plan in a storage device (server or the like) on the network. In this case, the radiation therapy device 4 receives the radiation therapy plan created by the radiation therapy planning device 3 from the storage device. As shown in FIG. 2 , the radiotherapy planning apparatus 3 includes a processing section 11 , a storage section 12 , a communication section 13 , an operation section 14 and a display section 15 .

The communication unit 13 is composed of a communication interface device such as a NIC (Network Interface Card) that performs communication via a network. The communication unit 13 receives the medical images transmitted from the medical image diagnostic apparatus 2 and supplies them to the processing unit 11 . The communication unit 13 also transmits the radiotherapy plan received from the processing unit 11 to the radiotherapy apparatus 4 .

The operation unit 14 is composed of an input interface device. Input interface devices include, for example, mice, keyboards, trackballs, switches, buttons, joysticks, touch pads, and touch panel displays. The operation unit 14 receives various input operations by the user and supplies electrical signals corresponding to the received input operations to the processing unit 11 .

The display unit 15 includes a display device such as a liquid crystal display (LCD), a CRT (Cathode Ray Tube) display, an organic EL display (OELD: Organic Electro Luminescence Display), or the like. The display unit 15 displays various information under the control of the processing unit 11 .

The storage unit 12 includes a storage device such as a ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or the like. Further, the storage unit 12 stores various programs and various data.

The storage unit 12 stores a lethal dose table. The lethal dose table, as shown in FIG. 3, shows doses required to eliminate tumors (lethal doses) for each type of tumor. The lethal dose is indicated, for example, as a dose per unit volume. The lethal dose is a measure of the radiosensitivity of a tumor, and indicates, for example, the dose that eliminates the tumor site with a probability of 95% or more. For example, when the tumor site to be treated is “lung cancer”, the processing unit 11 refers to the lethal dose table and sets a dose (dose rate, irradiation time) that is equal to or higher than the lethal dose corresponding to “lung cancer”.

The storage unit 12 also stores a tolerable dose table. The tolerable dose table shows, for each organ, the dose (tolerable dose) that can be tolerated by normal tissue sites. The tolerable dose indicates, for example, the dose per unit volume. The tolerable dose is a measure of the radiosensitivity of normal tissue sites, and indicates the dose at which the irradiated radiation does not cause serious adverse events. Normal tissue sites also include risk organs that have a reduced survival rate if there is radiation infiltration. The tolerable dose table, as shown in FIGS. 4(a) and 4(b), includes FLASH and general radiotherapy.

The tolerable dose table for general radiotherapy shows the tolerable dose for each organ. On the other hand, the FLASH-related tolerable dose table shows the radiation dose rate, tolerable irradiation time, and tolerable dose for each organ. FLASH protects the normal tissue site even when the normal tissue site is irradiated with a dose equivalent to the dose (tolerance dose) at which the normal tissue site is damaged in general radiotherapy (general radiotherapy) (damage not). In other words, in radiation therapy according to FLASH, the risk of damage to normal tissue sites varies depending on the dose rate of radiation. In the FLASH-related tolerable dose table, the tolerable dose for normal tissue sites is set to a larger value as the dose rate is higher. The tolerable irradiation time is determined based on the dose rate and the tolerable dose.

The storage unit 12 also stores various data for obtaining the distribution of the dose rate in the radiation irradiation path (beam path). For example, the storage unit 12 stores radiation absorption coefficient data, radiation attenuation rate data, penumbra area data, and the like.

The radiation absorption coefficient data is data indicating the radiation absorption coefficient for each living tissue, which indicates the ratio of energy absorbed by the living tissue per unit volume or unit length of the entering radiation. The radiation attenuation rate data is data indicating the relationship between the irradiation depth of radiation and the dose attenuation rate. For example, as shown in FIG. 5, the dose of radiation such as an electron beam is attenuated according to the depth inside the body to which the radiation is irradiated. In other words, the dose rate changes between the position where the radiation enters the patient and the position where the radiation exits, so the irradiation effect of the radiation differs. The penumbra area is an area where the radiation passing through the peripheral portion of the opening of the diaphragm among the irradiation rays that have passed through the opening of the multi-segment diaphragm (multi-leaf collimator) of the radiotherapy apparatus 4 is irradiated, and is the center of the opening. The dose rate is reduced compared to the dose rate of the radiation that passed through the part. The penumbra area data is data indicating the relationship between the position and size of the aperture of the diaphragm and the attenuation rate of radiation attenuated by the penumbra area formed on the edge of the aperture.

The processing unit 11 is composed of processors such as a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). The processing unit 11 controls the radiotherapy planning apparatus 3 as a whole by controlling each part of the radiotherapy planning apparatus 3 . Further, the processing unit 11 functions as a part extraction unit 111 , an irradiation plan creation unit 112 and an information output unit 113 by executing programs stored in the storage unit 12 . A part or all of the functions 111 to 113 may be configured by an integrated circuit such as an ASIC (Application Specific Integrated Circuit).

Processing operations performed by the radiotherapy planning apparatus 3 configured as described above will be described below with reference to FIGS. 6 and 7. FIG.

The part extraction unit 111 acquires a medical image generated by the medical image diagnostic apparatus 2 (step ST1). The medical image is, for example, a three-dimensional CT image generated by an X-ray computed tomography device (CT device) here, but a magnetic resonance imaging device (MRI), a cone beam CT device, a nuclear medicine diagnostic device (PET, Various medical images generated by SPECT, etc., may also be used. The site extraction unit 111 performs segmentation processing on the acquired medical image to extract the tumor site and the normal tissue site included in the medical image (step ST2). Note that the site extraction unit 111 may extract the tumor site and the normal tissue site according to the user's operation via the operation unit 14 .

The irradiation plan creation unit 112 determines the lethal dose of the tumor site, the dose rate threshold for obtaining the irradiation effect of FLASH (ultra-high dose rate short-term irradiation) on the normal tissue site, and the amount of radiation to be irradiated on the normal tissue site. Obtaining reference information representing the tolerable dose of the normal tissue site according to the dose rate. The irradiation plan creation unit 112 creates a radiation irradiation plan for irradiating the tumor site and the normal tissue site based on the acquired reference information. In the present embodiment, an example will be described in which the irradiation plan creation unit 112 creates an irradiation plan using a forward planning method. The irradiation plan creation unit 112 includes an irradiation condition setting unit 112a and an irradiation condition evaluation unit 112b.

The irradiation condition setting unit 112a sets irradiation conditions for FLASH for the tumor site and the normal tissue site extracted by the site extraction unit 111 (step ST3). For example, as shown in FIG. 7A, the user confirms the positional relationship between the tumor site and the normal tissue site included in the medical image displayed on the display unit 15, and the lethal dose displayed on the display unit 15. The irradiation conditions for FLASH are set by referring to the table and the tolerable dose table. The irradiation condition setting unit 112a, for example, as shown in FIG. Time, incident position of radiation (beam), incident direction (beam angle), opening degree of multi-leaf collimator (MLC), etc. are set.

Based on the irradiation conditions set by the irradiation condition setting unit 112a, the irradiation condition evaluation unit 112b obtains the dose of radiation applied to the tumor site and the dose rate and dose of radiation applied to the normal tissue site. In addition, the irradiation condition evaluation unit 112b determines the lethal dose of the tumor site, the threshold of the dose rate at which the normal tissue site obtains the irradiation effect related to FLASH (ultra-high dose rate short-term radiation irradiation), and the irradiation of the normal tissue site. Based on the reference information representing the tolerable dose of the normal tissue site according to the radiation dose rate, the radiation dose irradiated to the tumor site, and the radiation dose rate and dose irradiated to the normal tissue site, Create a radiation irradiation plan.

Specifically, the irradiation condition evaluation unit 112b obtains the radiation irradiation route (beam path) based on the irradiation conditions set by the irradiation condition setting unit 112a, and acquires the dose rate distribution in the irradiation route (step ST4 ). The irradiation condition evaluation unit 112b reads various data such as radiation absorption coefficient data, radiation attenuation rate data, and penumbra area data stored in the storage unit 12, and compares the read various data, the acquired medical image, and the set data. Based on the irradiation conditions, the radiation attenuation rate in the irradiation path is obtained, and the dose rate distribution in the irradiation path is obtained based on the radiation attenuation rate. The irradiation condition evaluation unit 112b acquires the dose rate distribution per unit volume.

Specifically, the irradiation condition evaluation unit 112b obtains the radiation attenuation rate according to the irradiation depth of the irradiation path by referring to the radiation attenuation rate data. In addition, the irradiation condition evaluation unit 112b identifies biological tissues such as a tumor site and a normal tissue site in the irradiation route of radiation. By referring to the radiation absorption coefficient data, the irradiation condition evaluation unit 112b obtains the radiation attenuation rate according to the radiation absorption coefficient of the living tissue identified in the irradiation path. Note that the radiation attenuation rate corresponding to the radiation absorption coefficient of the living tissue is obtained by considering the size (volume, length) of the living tissue included in the irradiation path. Furthermore, the irradiation condition evaluation unit 112b obtains a penumbra area corresponding to the edge of the aperture of the multi-segment diaphragm (multi-leaf collimator) of the radiotherapy apparatus 4. FIG. The irradiation condition evaluation unit 112b refers to the penumbra area data to obtain the radiation attenuation rate according to the penumbra area in the irradiation path.

The irradiation condition evaluation unit 112b integrates the radiation attenuation rate according to each of the irradiation depth, the radiation absorption coefficient, and the penumbra region, and acquires the dose rate distribution in the irradiation path based on the integrated attenuation rate. The irradiation condition evaluation unit 112b uses various data such as radiation absorption coefficient data, radiation attenuation rate data, and penumbra area data, acquired medical images, set irradiation conditions, and a predetermined dose calculation algorithm. Based on this, the distribution of the dose rate in the radiation irradiation path may be obtained. Predetermined dose calculation algorithms include, for example, the Monte Carlo method, the equivalent TAR (Tissue-Air Ratio) method, the differential scattering air dose ratio method, the microvolume method, the convolution method, and the like.

Further, the irradiation condition evaluation unit 112b may use a trained model that has been machine-learned so as to output the dose rate distribution in the radiation irradiation path based on the input of the medical image and the irradiation conditions. In this case, the irradiation condition evaluation unit 112b reads out the trained model stored in the storage unit 12, and inputs the medical image and radiation irradiation conditions to the trained model, thereby obtaining the radiation output from the trained model. You may acquire the distribution of the dose rate in the irradiation path|route of.

Based on the distribution of the dose rate in the irradiation route thus acquired (information acquired based on the irradiation conditions), the irradiation condition evaluation unit 112b determines the dose of radiation irradiated to the tumor site, the dose of radiation irradiated to the normal tissue site, Determine the dose rate and dose of the radiation delivered.

The irradiation condition evaluation unit 112b obtains the dose of radiation applied to the tumor site and evaluates the irradiation effect on the tumor site (step ST5). Specifically, the irradiation condition evaluation unit 112b acquires the dose rate distribution of the tumor site included in the irradiation route from among the dose rate distributions acquired in step ST4. Further, the irradiation condition evaluation unit 112b acquires the irradiation time for irradiating the tumor site based on the radiation irradiation conditions set in step ST3. The irradiation condition evaluation unit 112b obtains the distribution of the dose applied to the tumor site from the distribution of the dose rate of the tumor site and the irradiation time. The irradiation condition evaluation unit 112b reads the lethal dose table shown in FIG.

Based on the distribution of the dose of radiation irradiated to the tumor site, the irradiation condition evaluation unit 112b determines the distribution of the dose of radiation irradiated to the tumor site that exceeds the lethal dose and the distribution of the dose that is equal to or less than the lethal dose. distinguish between The irradiation condition evaluation unit 112b gives identification information indicating that irradiation is sufficient for regions showing a distribution exceeding the lethal dose, and indicates that irradiation is insufficient for regions showing a distribution below the lethal dose. Assign identification information.

The irradiation condition evaluation unit 112b superimposes and displays on the medical image information that can be visually identified to indicate that the irradiation dose of the region is sufficient, such as by enclosing the region showing the distribution exceeding the lethal dose with a blue line. You may make it display on the part 15. The irradiation condition evaluation unit 112b superimposes, on the medical image, information that can visually identify that the irradiation dose of the region is insufficient, such as by enclosing the region showing the distribution of the lethal dose or less with a purple line. It may be displayed on the display unit 15 . The lethal dose table shown in FIG. 3 may also indicate the lethal dose and the lethal irradiation time according to the dose rate. The irradiation condition evaluation unit 112b assigns identification information indicating that the irradiation dose is sufficient to regions exceeding the lethal dose associated with each dose rate indicated by the distribution of the tumor site, and indicates the distribution below the lethal dose. Areas are given identification information indicating that they are under-illuminated. In this way, the irradiation effect on the tumor site is evaluated.

As another method for assigning identification information, the irradiation condition evaluation unit 112b obtains the ratio of the region exceeding the lethal dose and the region below the lethal dose of the tumor site, and according to the ratio, the tumor site , identification information may be added to identify whether the lethal dose is exceeded.

In addition, the irradiation condition evaluation unit 112b obtains the dose rate and dose of radiation applied to the normal tissue site, and evaluates the irradiation effect on the normal tissue site. Specifically, the irradiation condition evaluation unit 112b acquires the dose rate and the irradiation time of the radiation irradiated to the normal tissue site included in the irradiation route (step ST6). The irradiation condition evaluation unit 112b selects one normal tissue site from the plurality of normal tissue sites when the irradiation path includes a plurality of normal tissue sites. The irradiation condition evaluation unit 112b acquires the dose rate distribution of the selected normal tissue site. Further, the irradiation condition evaluation unit 112b acquires the irradiation time for irradiation of the selected normal tissue site based on the radiation irradiation conditions set in step ST3.

The irradiation condition evaluation unit 112b identifies whether or not the dose rate is equal to or higher than the threshold for obtaining the irradiation effect of FLASH, based on the distribution of the dose rate of the radiation irradiated to the selected normal tissue region (step ST7). . It is known that the effect of FLASH is obtained at a high dose rate of, for example, 40 Gy/s or higher. ). The irradiation condition evaluation unit 112b indicates the distribution of the dose rate below the threshold (for example, 40 Gy/s) (the area where the effect of FLASH is not obtained) and the distribution of the dose rate above the threshold for the selected normal tissue part. area (the area where the effect of FLASH is obtained).

Further, the irradiation condition evaluation unit 112b identifies whether or not the tolerable dose of the selected normal tissue site is exceeded based on the dose rate distribution and the irradiation time of the selected normal tissue site (step ST8). Specifically, the irradiation condition evaluation unit 112b reads the tolerable dose table shown in FIG. In radiation therapy for FLASH, the risk of damage to normal tissue sites varies depending on the radiation dose rate. In other words, even if radiation is irradiated at a dose rate equal to or higher than the threshold (for example, 40 Gy/s) in step ST6, depending on the dose rate and irradiation time of the radiation, the tolerable dose of the normal tissue site corresponding to the dose rate may be exceeded. It is necessary to identify whether or not The irradiation condition evaluation unit 112b determines whether the selected normal tissue region can withstand FLASH irradiation based on the dose rate and irradiation time of the radiation irradiated to the selected normal tissue region and the tolerable dose corresponding to the dose rate. Distinguish between areas and areas that cannot withstand FLASH irradiation.

The irradiation condition evaluation unit 112b evaluates the irradiation effect on the normal tissue site selected in step ST6 based on the identification results in steps ST7 and ST8. Specifically, the irradiation condition evaluation unit 112b, among the selected normal tissue parts, for the region identified as the region where the effect of FLASH can be obtained and the region that can withstand the irradiation of FLASH (step ST7; Yes, step ST8; No), identification information (for example, information indicating that the irradiation risk is small) for identifying that irradiation of radiation according to FLASH can be performed normally is given (step ST9). The irradiation condition evaluation unit 112b may superimpose visually identifiable information indicating that the region can be irradiated, such as by enclosing the region of the normal tissue site with a green line, and cause the display unit 15 to display the information. good.

On the other hand, the irradiation condition evaluation unit 112b, among the selected normal tissue parts, for the region identified as the region where the effect of FLASH is not obtained or the region that cannot withstand the irradiation of FLASH (step ST7; No , step ST8; Yes), identification information (for example, information indicating that the irradiation risk is high) for identifying that irradiation of radiation for FLASH cannot be performed normally is given (step ST10). The irradiation condition evaluation unit 112b superimposes visually identifiable information indicating that the region cannot be irradiated by, for example, surrounding the region of the normal tissue site with a red line, and causes the display unit 15 to display the superimposed information. good too. In this way, the irradiation effect on the normal tissue site selected in step ST6 is evaluated.

In addition, the irradiation condition evaluation unit 112b obtains the ratio of a region with a low irradiation risk and a region with a high irradiation risk in a normal tissue region, and irradiates the normal tissue region with radiation according to FLASH according to the ratio. You may output so that it can identify whether it can be performed normally.

After that, the irradiation condition evaluation unit 112b determines whether or not there is another normal tissue site on the irradiation path (step ST11). Then, the process of ST10 is performed (step ST11; Yes).

Through the above processing, the irradiation conditions set in step ST3 are evaluated. The irradiation plan creation unit 112 displays on the display unit 15 information representing the evaluation result of the irradiation conditions by the irradiation condition evaluation unit 112b. Based on the information, the user can check whether there are areas in the normal tissue site where the effect of FLASH is not obtained, areas that cannot withstand FLASH irradiation, or areas where the dose to the tumor site is insufficient. It is determined whether or not it is necessary to set the irradiation conditions for . When the irradiation plan creation unit 112 determines that other irradiation conditions need to be set according to the user's operation via the operation unit 14, the irradiation plan generation unit 112 returns to step ST3 and resets the irradiation conditions ( Step ST12; Yes).

On the other hand, when the irradiation plan creation unit 112 determines that other irradiation conditions need not be set according to the user's operation via the operation unit 14, the irradiation condition evaluated by the irradiation condition evaluation unit 112b is used. Based on this, a radiation irradiation plan is created (step ST13). The information output unit 113 outputs information based on the irradiation plan created by the irradiation plan creation unit 112 to the storage unit 12 and the display unit 15 . In addition, the information output unit 113 outputs information based on the irradiation plan created by the irradiation plan creating unit 112 to the radiotherapy apparatus 4 through the communication unit 13 according to the user's operation through the operation unit 14. .

According to the above-described processing operations, the radiotherapy planning apparatus 3 displays the irradiation effect on the tumor site and the irradiation effect on the normal tissue site in a identifiable manner based on the set irradiation conditions. can be provided. In particular, with regard to the irradiation effect on normal tissue sites, areas where the FLASH effect is obtained and areas where the FLASH effect is not obtained are determined based on the distribution of the dose rate of radiation irradiated to the normal tissue site. can be distinguished. In addition, considering the risk of damage to normal tissue sites according to the dose rate of radiation, based on the dose rate and irradiation time of radiation irradiated to normal tissue sites and the tolerable dose corresponding to the dose rate, A distinction can be made between areas that are tolerant of FLASH irradiation and areas that are not tolerant of FLASH irradiation.

In the above embodiment, in steps ST9 and ST10, an example was described in which identification information for identifying whether FLASH irradiation can be performed normally is given to a normal tissue site, but the irradiation condition evaluation unit 112b Identification information that identifies whether the dose rate is above the threshold (information that identifies whether the effect of FLASH is obtained) and identification information that identifies whether the tolerable dose of normal tissue sites is exceeded (FLASH (information for identifying whether or not the irradiation can be tolerated) may be individually given to the corresponding region of the normal tissue site or to the normal tissue site.

In the above embodiment, in step ST12, an example was described in which it is determined whether or not other irradiation conditions need to be set according to the user's operation. Depending on the evaluation results of the irradiation conditions, the irradiation conditions set in step ST3 may be automatically determined, and a notification to that effect may be displayed on the display unit 15 . Further, the irradiation plan creation unit 112 may display on the display unit 15 a notification prompting resetting of the irradiation conditions set in step ST3 according to the evaluation result of the irradiation conditions by the irradiation condition evaluation unit 112b. For example, the irradiation condition evaluation unit 112b, in the normal tissue site, when it is identified that there is a region in which the effect of FLASH is not obtained, or a region that can not withstand the irradiation of FLASH (step ST7; No or step ST8; If yes), the process may return to step ST3 and display a notification on the display unit 15 prompting resetting of the irradiation conditions. In this case, in step ST12, the user confirms that the effect of FLASH is obtained in all areas of the normal tissue site. Even in this case, the irradiation plan creation unit 112 accepts the user's operation via the operation unit 14, and determines whether or not it is necessary to set other irradiation conditions according to the user's operation. good.

In the above embodiment, as another irradiation condition, an example of resetting the irradiation condition related to FLASH has been described. Irradiation conditions may be set. In this case, the irradiation condition setting unit 112a sets the irradiation conditions (irradiation plan) for general radiotherapy so that the dose of radiation irradiated to the normal tissue region is minimized and the tumor region is irradiated with radiation, as in the conventional case. to create The irradiation condition evaluation unit 112b acquires the dose distribution in the radiation irradiation path (beam path) based on the set irradiation conditions, and obtains the dose of radiation irradiated to the tumor site and the normal tissue site. The irradiation condition evaluation unit 112b reads out the lethal dose table for the tumor site from the storage unit 12, and identifies whether or not the radiation dose applied to the tumor site exceeds the lethal dose. The irradiation condition evaluation unit 112b also reads out the tolerable dose table shown in FIG. 4B from the storage unit 12, and identifies whether or not the radiation dose applied to the normal tissue site exceeds the tolerable dose. The irradiation plan creation unit 112 displays on the display unit 15 information representing the evaluation result of the irradiation conditions related to general radiotherapy by the irradiation condition evaluation unit 112b.

Furthermore, the irradiation plan creation unit 112 automatically resets the irradiation conditions set in step ST3 and evaluates the reset irradiation conditions according to the evaluation result of the irradiation conditions by the irradiation condition evaluation unit 112b. may also be used (irradiation effects may be simulated).

In the above embodiment, the number of times of irradiation and the number of incident directions were not mentioned for convenience of explanation, but irradiation conditions including the number of times of irradiation and the number of incident directions may be set in step ST3. In this case, the irradiation plan creating unit 112 acquires irradiation information representing the distribution of the dose rate of the radiation irradiated to the normal tissue region and the irradiation time in consideration of the number of times of processing and the number of incident directions.

Further, in the above embodiment, an example (40 Gy/s) in which the dose rate threshold for obtaining the irradiation effect of FLASH is uniformly set has been described. may be set. In this case, the irradiation condition evaluation unit 112b, based on the threshold corresponding to the organ represented by the selected normal tissue site, for the normal tissue site, the region showing the distribution of the dose rate below the threshold (the effect of FLASH is obtained) area where the dose rate is above the threshold (area where the FLASH effect is obtained).

Furthermore, the irradiation condition evaluation unit 112b explained an example using the tolerable dose table related to FLASH shown in FIG. The dose rate that is not obtained may be obtained by complementing the tolerable dose and tolerable irradiation time by calculation.

In addition, the irradiation plan creation unit 112 may create an irradiation plan for FLASH and an irradiation plan for general radiotherapy separately and display them on the display unit 15 . For example, by displaying the irradiation plan for FLASH and the irradiation plan for general radiotherapy side by side on the display unit 15, the user can easily compare the irradiation plan for FLASH and the irradiation plan for general radiotherapy. Become.

Further, the irradiation plan creation unit 112 may create an irradiation plan combining FLASH-related irradiation and general radiotherapy-related irradiation, or a combination of multiple FLASH-related irradiations. For example, the irradiation plan creation unit 112 creates a low FLASH irradiation plan based on a dose rate (for example, about 50 Gy/s) close to the dose rate threshold for obtaining the irradiation effect of FLASH, and the dose rate threshold for obtaining the irradiation effect of FLASH. You may create an irradiation plan combined with a high FLASH irradiation plan based on a dose rate (for example, about 500 Gy/s) far exceeding .

(Embodiment 2)
In Embodiment 1, the irradiation plan creation unit 112 sets the irradiation conditions related to FLASH according to the user's operation via the operation unit 14, and creates an irradiation plan by a forward planning technique. In the present embodiment, an example of automatically creating an irradiation plan by an inverse planning method will be described.

For example, as shown in FIG. 8, the processing unit 11 functions as a part extraction unit 111, an irradiation plan creation unit 112, and an information output unit 113 by executing programs stored in the storage unit 12. FIG.

Processing operations performed by the radiotherapy planning apparatus 3 will be described below with reference to FIG.

The site extraction unit 111 acquires the medical image generated by the medical image diagnostic apparatus 2 (step ST21), and extracts the tumor site and the normal tissue site included in the medical image (step ST22).

The irradiation plan creation unit 112 determines the lethal dose of the tumor site, the dose rate threshold (for example, 40 Gy/s) at which the normal tissue site obtains the irradiation effect related to FLASH (ultra-high dose rate short-term radiation irradiation), and the normal tissue site acquires reference information representing the tolerable dose of the normal tissue site according to the dose rate of the radiation irradiated to the body; The irradiation plan creation unit 112 creates a radiation irradiation plan for irradiating the tumor site and the normal tissue site based on the acquired reference information.

Specifically, the irradiation plan creating unit 112 reads the lethal dose table shown in FIG. A target dose (first criterion) equal to or greater than the dose is set for the tumor site (step ST23).

In addition, the irradiation plan creation unit 112 sets the target dose rate (second criterion) of the radiation irradiated to the normal tissue site extracted in step ST22 as a dose rate threshold (for example, 40 Gy/ s) Set above (step ST24).

In addition, the irradiation plan creation unit 112 sets the target dose (third criterion) for the normal tissue site extracted in step ST22 to be equal to or less than the tolerable dose corresponding to the dose rate of the radiation irradiated to the normal tissue site. (Step ST25). If there are a plurality of normal tissue sites extracted in step ST22, a target dose (third criterion) is set for each normal tissue site.

The irradiation plan creating unit 112 creates an irradiation condition (irradiation plan) for FLASH that satisfies the set first to third criteria (step ST26). For example, the irradiation plan creation unit 112 sets a plurality of irradiation conditions, simulates the irradiation effect related to FLASH for each set irradiation condition, and as a result, the optimum irradiation conditions that satisfy the first to third criteria Obtain the (irradiation plan). As a result, the irradiation plan creation unit 112 determines that the dose of radiation irradiated to the tumor site becomes equal to or greater than the lethal dose of the tumor site, and the dose rate of the radiation irradiated to the normal tissue site is the dose rate that obtains the irradiation effect related to FLASH. Radiation irradiation conditions ( irradiation plan) is obtained.

The information output unit 113 outputs information based on the irradiation plan created by the irradiation plan creation unit 112 to the storage unit 12 and the display unit 15 . Specifically, the information output unit 113 outputs identification information for identifying the irradiation effect on the tumor site and the normal tissue site (identification information indicating sufficient irradiation for the tumor site, irradiation risk for the normal tissue site, is displayed on the display unit 15 by superimposing it on the medical image. In addition, the information output unit 113 outputs information based on the irradiation plan created by the irradiation plan creation unit 112 to the radiotherapy apparatus 4 through the communication unit 13 according to the user's operation through the operation unit 14. may

Note that the irradiation plan creation unit 112 is learned by machine learning so as to output irradiation conditions (irradiation plans) for FLASH that satisfy the first to third criteria based on the input of the tumor site and the normal tissue site. A ready-made model may also be used. In this case, the irradiation plan creation unit 112 reads out the learned model stored in the storage unit 12, inputs the tumor site and the normal tissue site extracted from the medical image into the learned model, and performs the learning. The irradiation conditions for FLASH output from the finished model may be set.

Further, the irradiation plan creating unit 112 may create a plurality of irradiation conditions (irradiation plans) satisfying the first to third criteria. In this case, the information output unit 113 outputs the list of irradiation conditions to the display unit 15 . The information output unit 113 selects one irradiation condition (irradiation plan) from the list according to the user's operation via the operation unit 14, and determines the irradiation plan.

Moreover, the site extraction unit 111 may specify at least one of the tumor site and the normal tissue site based on the user's operation via the operation unit 14 . The irradiation plan creation unit 112 may acquire FLASH-related irradiation conditions that satisfy the first to third criteria for the tumor site or normal tissue site specified based on the operation.

In addition, the irradiation plan creation unit 112 may create a treatment plan for general radiotherapy (general radiotherapy). In this case, as in the conventional case, the irradiation plan creation unit 112 minimizes the dose of radiation irradiated to the normal tissue site, and sets the irradiation conditions (irradiation plan) for general radiotherapy so that the tumor site is irradiated with radiation. to create

In addition, the irradiation plan creation unit 112 may create an irradiation plan for FLASH and an irradiation plan for general radiotherapy separately and display them on the display unit 15 . For example, by displaying the irradiation plan for FLASH and the irradiation plan for general radiotherapy side by side on the display unit 15, the user can easily compare the irradiation plan for FLASH and the irradiation plan for general radiotherapy. Become.

Further, the irradiation plan creation unit 112 may create an irradiation plan combining FLASH-related irradiation and general radiotherapy-related irradiation, or a combination of multiple FLASH-related irradiations. For example, the irradiation plan creation unit 112 creates a low FLASH irradiation plan based on a dose rate (for example, about 50 Gy/s) close to the dose rate threshold for obtaining the irradiation effect of FLASH, and the dose rate threshold for obtaining the irradiation effect of FLASH. You may create an irradiation plan combined with a high FLASH irradiation plan based on a dose rate (for example, about 500 Gy/s) far exceeding .

According to at least one embodiment described above, it is possible to provide a radiotherapy plan that suppresses damage to normal tissue sites and appropriately obtains irradiation effects.

The term "processor" used in the above description includes, for example, CPU, GPU, or Application Specific Integrated Circuit (ASIC), programmable logic device (for example, Simple Programmable Logic Device: SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)). The processor realizes its functions by reading and executing the programs stored in the memory circuit. It should be noted that instead of storing the program in the memory circuit, the program may be directly installed in the circuit of the processor. In this case, the processor realizes its function by reading and executing the program embedded in the circuit. Also, functions corresponding to the program may be realized by combining logic circuits instead of executing the program. Note that each processor of the present embodiment is not limited to being configured as a single circuit for each processor, and may be configured as one processor by combining a plurality of independent circuits to realize its function. good.

While several embodiments have been described, these embodiments are provided 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, changes, and combinations of embodiments 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 radiotherapy system 2 medical image diagnostic apparatus 3 radiotherapy planning apparatus 4 radiotherapy apparatus 11 processing unit 111 part extraction unit 112 irradiation plan creation unit 112a irradiation condition setting unit 112b irradiation condition evaluation unit 113 information output unit 12 storage unit 13 communication unit 14 operation unit 15 display unit

Claims (11)

a site extraction unit that extracts a tumor site and a normal tissue site included in a medical image;
Depending on the lethal dose of the tumor site, the dose rate threshold for obtaining the irradiation effect of FLASH (ultra high dose rate short-term irradiation) on the normal tissue site, and the dose rate of the radiation irradiated on the normal tissue site an irradiation plan creation unit that acquires reference information representing a tolerable dose of the normal tissue site, and creates an irradiation plan for irradiating the tumor site and the normal tissue site based on the acquired reference information;
An information output unit that outputs information based on the created irradiation plan,
Radiotherapy planning equipment. The irradiation plan creation unit,
an irradiation condition setting unit that sets irradiation conditions related to FLASH for the tumor site and the normal tissue site extracted by the site extraction unit;
an irradiation condition evaluation unit that calculates the dose of radiation applied to the tumor site and the dose rate and dose of radiation applied to the normal tissue site based on the irradiation conditions set by the irradiation condition setting unit; prepared,
The irradiation condition evaluation unit creates the irradiation plan based on the reference information, the dose of radiation irradiated to the tumor site, and the dose rate and dose of radiation irradiated to the normal tissue site.
A radiotherapy planning apparatus according to claim 1 . The irradiation condition evaluation unit, based on the dose rate distribution and the irradiation time, identifies whether the tolerable dose or the tolerable irradiation time corresponding to the dose rate is exceeded,
A radiotherapy planning apparatus according to claim 2. The irradiation condition evaluation unit identifies whether the dose rate included in the irradiation information is equal to or higher than the dose rate that obtains the effect of FLASH,
A radiotherapy planning apparatus according to claim 2. The irradiation condition evaluation unit obtains the irradiation route of the radiation based on the irradiation conditions, and acquires the distribution of the dose rate in the irradiation route.
A radiotherapy planning apparatus according to any one of claims 2 to 4. The irradiation condition evaluation unit obtains the radiation attenuation rate in the irradiation route, and acquires the dose rate distribution in the irradiation route based on the radiation attenuation rate.
A radiotherapy planning apparatus according to claim 5 . The irradiation condition evaluation unit obtains a radiation attenuation rate according to the irradiation depth of the irradiation route,
A radiotherapy planning apparatus according to claim 5 . The irradiation condition evaluation unit obtains a radiation attenuation rate according to the radiation absorption coefficient of living tissue in the irradiation route,
A radiotherapy planning apparatus according to claim 5 . The irradiation condition evaluation unit obtains an attenuation rate of radiation according to a penumbra region in the irradiation path,
A radiotherapy planning apparatus according to claim 5 . The irradiation condition evaluation unit determines a plurality of the irradiation conditions,
the information output unit outputs a list of the plurality of irradiation conditions;
Radiation therapy planning apparatus according to any one of claims 2 to 9. The site extraction unit extracts at least one of the tumor site and the normal tissue site based on a user's operation.
Radiation therapy planning apparatus according to any one of claims 1 to 10.

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