JP2018187089A - Treatment planning device - Google Patents

Abstract

Provided is a treatment planning apparatus capable of creating a treatment plan in consideration of robustness against uncertainty at the time of treatment more easily than in the past.
An optimization calculation is performed by changing the importance w of a robust term, and the obtained dose distribution is stored in a data storage device 206. When the operator sets the importance w of the robust term by moving the slider 801A on the GUI, the dose distribution calculated using the parameter closest to the set importance w of the robust term is searched from the data storage device 206. The dose distribution at the set importance w is obtained by interpolation. Then, DVHs 802A and 802B and DVH bands 803A and 803B are obtained from the obtained dose distribution and the like and displayed on the display device 203.
[Selection] Figure 8

Description

  The present invention relates to a treatment planning apparatus.

  In radiation therapy, treatment is performed by irradiating a target tumor cell with radiation. Although X-rays are the most widely used treatment using radiation, there is a demand for treatments using proton beams and particle beams (charged particle beams) typified by carbon rays that have high dose concentration to the target. It is growing.

  In radiotherapy, excessive irradiation and insufficient dose can lead to side effects on normal tissues other than tumors and tumor recurrence. Therefore, also in the particle beam therapy system, it is required to irradiate a specified dose of radiation so as to concentrate on the tumor region as accurately as possible and as much as possible.

  In particle beam therapy, the use of the scanning method is spreading as a method of concentrating the dose. This is a method in which a thin particle beam is deflected by two sets of scanning electromagnets and guided to an arbitrary position in a plane to irradiate the tumor so as to fill the inside of the tumor, thereby giving a high dose only to the tumor region.

  In order to realize the scanning method, a process of creating a plan using a treatment planning apparatus before actual irradiation is extremely important. The treatment planning device is a device that simulates a dose distribution in a patient by numerical calculation based on information in the patient obtained from a CT image or the like. The operator determines irradiation conditions such as the direction of beam irradiation, beam energy, irradiation position, and dose while referring to the calculation result of the treatment planning apparatus. The general process is described below.

  The operator first inputs a target area to be irradiated with radiation. A CT image is mainly used, and a target region is input to each slice of the image. The input data is stored in the memory on the treatment planning apparatus as three-dimensional area data when the operator registers it in the treatment planning apparatus. If necessary, enter and register the positions of important organs in the same way.

  Next, the operator sets a prescription dose that becomes a target dose value for each registered region. The setting is made for the previously registered target area and important organ. For example, in the target area, a dose sufficient to necrotize the tumor is specified. In many cases, the dose value to be delivered to the target area is specified. On the other hand, for important organs, an allowable dose is determined as the maximum tolerable dose value. The beam irradiation position and dose for realizing the dose distribution designated by the operator are determined by the treatment planning apparatus. Usually, the irradiation position is determined first, and then the irradiation dose is determined so as to satisfy the dose distribution condition input by the operator.

As a method for efficiently determining the irradiation dose, as described in Non-Patent Document 1, the deviation between the dose d _i and the prescription dose p at the dose evaluation point i arranged in the region of interest (target, dangerous organ) is quantified. A method using the objective function F _d (see equation (1)) is widely adopted.

  This objective function is an objective function (dose constraint term) that represents the degree of achievement of the dose constraint, and is defined so that the dose distribution becomes smaller as the prescription dose is satisfied. The optimum irradiation dose is calculated by searching for a spot irradiation dose that minimizes this by iterative calculation.

Special table 2014-503315 gazette

A Lomax, “Intensity modulation methods for proton radiotherapy” Phys. Med. Biol. 44 (1999) 185-205. A Lomax, “Intensity modulated proton therapy and its sensitivity to treatment uncertainties 1: the potential effects of calculation uncertainties” Phys. Med. Biol. 53 (2008) 1027-1042 A Lomax, “Intensity modulated proton therapy and its sensitivity to treatment uncertainties 2: the potential effects of inter-fraction and inter-field motions” Phys. Med. Biol. 53 (2008) 1043-1056

  There is intensity modulated proton therapy (IMPT) as a treatment method that takes advantage of the scanning method. This IMPT forms a non-uniform dose distribution in each irradiation direction, and by adding the dose distributions from all irradiation directions, it suppresses the irradiation to organs (important organs) where the dose should be kept low while minimizing the tumor. It is possible to form a desired dose distribution in the region.

  However, in IMPT, since a desired dose distribution is formed by forming and adding non-uniform dose distributions from a plurality of irradiation directions, there is a problem that it is easily affected by uncertainty during treatment.

  Specifically, as described in Non-Patent Document 2 and Non-Patent Document 3, the uncertainties during treatment include patient positioning uncertainties (positioning errors) and CT values converted into water equivalent thicknesses. There are uncertainties such as uncertainties (range errors). When these uncertainties occur, there is a concern that the dose distribution in the patient may deteriorate due to an increase in the dose of important organs or a decrease in the target dose due to high-density substances such as bone existing near the irradiation position. The

  Therefore, when creating an IMPT treatment plan, it is desirable to create a treatment plan not only whether the desired dose distribution is satisfied, but also considering the robustness of the plan with respect to uncertainty during treatment.

  As a method for taking into account the influence of uncertainty during treatment when creating a treatment plan, a method has been proposed in which a term representing the robustness of the dose distribution (hereinafter referred to as robust term) is added to the objective function (see Non-Patent Document 3). . An example of this is the worst case optimization method.

In the worst case optimization method, an error generation condition is assumed in advance, a dose distribution under a plurality of error generation conditions is calculated, and a dose value and a prescription dose p at a dose evaluation point i under the error generation condition are calculated. the divergence calculated, defining the sum of the maximum value as a robust claim F _R. The robust term is defined by the following equation (2).

Here, d _i ^c represents a dose value of the dose evaluation point i of the error occurrence condition c, w represents the importance of the robust terms.

  The objective function is set by adding the robust term and the dose constraint term in equation (1) as the objective function, and the influence on the dose distribution due to uncertainty during treatment is suppressed. A treatment plan can be created. Further, the larger the importance w of the robust term is set, the more the distribution that emphasizes the robustness of the dose distribution is derived.

  When creating an IMPT treatment plan, it is important to balance the weight of the dose constraint term and the robust term of the objective function used for the optimization calculation. If the dose constraint term is emphasized, the dose distribution approaches the prescribed distribution, but a weak dose distribution may be derived from the uncertainty during treatment. Therefore, when creating an IMPT treatment plan, dose calculation is performed using the irradiation spot obtained as a result of optimization calculation, and DVH (Dose Volume Histogram) and dose distribution are calculated and robust under a plurality of error generation conditions. It is necessary to evaluate the property (see Patent Document 1).

  FIG. 1 shows a flow of creating a treatment plan of a conventional treatment planning apparatus. As shown in FIG. 1, after the start, the operator sets the weight of the robust term for the treatment planning device (step S101). Next, the execution of the irradiation amount optimization calculation is instructed (step S102). Thereafter, the calculated and displayed dose distribution calculation result and robustness are evaluated (step S103). Next, it is determined whether or not the dose distribution evaluated in step S103 is according to the target (step S104). If it is determined that the target is achieved, the process is terminated. If it is determined that the target is not achieved, the process returns to step S101, and the process starts again from the robust term weight setting.

  As described above, in the conventional treatment planning apparatus, if the robustness does not satisfy the desired condition, the robustness weight is changed by trial and error, the robustness is evaluated again, and an appropriate dose constraint term and robustness are evaluated. This had to be repeated until the balance of terms was achieved. Therefore, it has been difficult to easily create a treatment plan that takes into account the robustness with respect to uncertainty during treatment.

  An object of this invention is to provide the treatment plan apparatus which can produce the treatment plan which considered robustness with respect to the uncertainty at the time of treatment more simply than before.

  In order to solve the above problems, for example, the configuration described in the claims is adopted.

The present invention includes a plurality of means for solving the above-described problems. For example, the present invention is a treatment planning apparatus for creating a treatment plan for radiation therapy, which is a robust dose distribution of radiation irradiated to a target. An input unit for changing and inputting parameters related to sex and a dose distribution in which parameters related to robustness are changed by a specified number are calculated in advance, and the parameter input in the input unit is calculated from the closest dose distribution. A dose distribution with the input parameters is interpolated, a calculation unit for calculating DVH and DVH band under the condition that an error occurs from the dose distribution obtained by the interpolation calculation, and the calculation unit calculated by the calculation unit And a display unit for displaying DVH and the DVH band.
The present invention also provides an input unit for changing / inputting parameters related to the robustness of the dose distribution of radiation applied to the target, and calculating the dose distribution in the parameters input in the input unit, and calculating the calculated dose distribution. And a display unit for displaying the DVH and the DVH band calculated by the calculation unit, and a display unit for displaying the DVH and the DVH band calculated by the calculation unit. An adjustment unit for changing / inputting the parameter is displayed, and the parameter is changed / input by operating the input unit to change the adjustment unit.

  According to the present invention, it is possible to more easily create a treatment plan that takes into account the robustness with respect to the uncertainty during treatment.

It is a flowchart showing the flow until the treatment plan which considered robustness is drawn when using a general treatment plan apparatus. It is explanatory drawing which shows the structure of the treatment planning apparatus of Example 1 of this invention. It is a flowchart which shows the flow of a process until it draws up the treatment plan which considered robustness when the treatment plan apparatus of Example 1 is used. It is a flowchart explaining the process at the time of creating the treatment plan in consideration of the robustness by the treatment plan apparatus of Example 1. FIG. It is a flowchart which shows the flow of a process until it produces a plan candidate database when the treatment planning apparatus of Example 1 is used. It is a flowchart explaining the process at the time of creating the CT plan candidate database by the treatment plan apparatus of Example 1. FIG. It is the figure which showed the state which input and registered the target area | region and the important organ on CT screen. It is explanatory drawing which showed GUI (Graphical User Interface) for adjusting the balance of a dose restriction | limiting term and a robust term in the treatment planning apparatus of Example 1. FIG. It is a flowchart explaining the process at the time of DVH band calculation in the treatment plan apparatus of Example 1. FIG. It is a flowchart explaining the process at the time of final treatment plan preparation in the treatment plan apparatus of Example 1. FIG. It is explanatory drawing which showed GUI at the time of referring the information of each DVH band in the treatment planning apparatus of Example 1. FIG. It is explanatory drawing which showed GUI for adjusting the balance of a dose restriction term and a robust term in the treatment plan apparatus of Example 2. FIG.

  Embodiments of a treatment planning apparatus of the present invention and a treatment planning method using the treatment planning apparatus will be described below with reference to the drawings.

<Example 1>
A first embodiment of a treatment planning apparatus and a treatment planning method using the treatment planning apparatus according to the present invention will be described with reference to FIGS. In FIG. 2, the whole structure of the treatment plan apparatus 201 of a present Example is shown.

  The treatment planning apparatus 201 according to the present embodiment is an apparatus that makes a treatment plan for particle beam therapy using a scanning irradiation method. As shown in FIG. 2, the treatment planning apparatus 201 includes an input device (input unit) 202, a display device (display unit) 203, a memory 204, an arithmetic processing device (calculation unit) 205, and a data storage device (memory). Unit) 206 and a communication device 207. The treatment planning apparatus 201 is connected to the data server 208 via a network. Specifically, the communication device 207 in the treatment planning device 201 is connected to the data server 208 via a network, and exchanges data based on the control of the communication device 207.

  The input device 202 is a device for an operator to input various information and execution, setting change, and termination of various processes when creating a treatment plan, and is, for example, a keyboard or a mouse.

  The display device 203 is a display device for providing information to the operator when inputting various information necessary for creating a treatment plan and execution, setting change, and termination of various processes.

  The memory 204 is a storage device that temporarily stores information used in various types of arithmetic processing in the arithmetic processing unit 205 described later.

  The arithmetic processing unit 205 calculates a DVH and a DVH band that is a DVH at the time of uncertainty occurrence from the main arithmetic unit 205A that calculates the irradiation amount of the spot by optimization calculation and data stored in the data storage unit 206. And a DVH band calculation unit 205B. The arithmetic processing device 205 is connected to the input device 202, the display device 203, the memory 204, the data storage device 206, and the communication device 207.

  As will be described in detail later, the arithmetic processing unit 205 of the present embodiment uses the DVH band calculation unit 205B to determine a parameter related to robustness (in this embodiment, a robust term in the objective function in which the deviation from the prescription dose is quantified). The designated number of plan candidate data consisting of dose distributions with varying importance) is calculated. Further, the dose distribution with the input parameters is obtained by interpolation from the plan candidate data having the closest parameter specified by the slider 801A (see FIG. 8) on the slider bar 801B (see FIG. 8). Then, a DVH and a DVH band which is a DVH at the time of occurrence of uncertainty are calculated from the dose distribution obtained by complementation and output to the display device 203.

  Further, when the main processing unit 205A calculates the dose distribution, the arithmetic processing unit 205 calculates the dose distribution based on DVH obtained indirectly by interpolation.

  Further, when the DVH band on which the input device 202 is operated is selected, the arithmetic processing unit 205 displays the DVH band generation condition and the difference value with the DVH on the display device 203 by the DVH band calculation unit 205B. Processing and control to display on the screen.

  In addition, the arithmetic processing unit 205 performs DVH normalization processing by the DVH band calculation unit 205B. For example, when the DVH hand at the time when the error occurs most is selected, the DVH band is normalized so as to be displayed as DVH, and arithmetic processing and control are performed so that the DVH hand is displayed on the display device 203.

  The data storage device 206 is a storage device that stores various types of information used for processing of each device in the treatment planning device 201. In the data storage device 206 of the present embodiment, the data candidate plan calculated by the arithmetic processing device 205 is stored by the designated number.

  Next, with reference to FIG. 3 to FIG. 11, a treatment plan planning method using the treatment planning apparatus 201 according to the present embodiment will be described in connection with functions and operations of each device in the treatment planning apparatus 201.

  First, the processing flow of the operator when creating a treatment plan and the processing flow of the treatment planning apparatus 201 will be described below with reference to FIGS. FIG. 3 shows a processing flow of the operator when creating a treatment plan, and FIG. 4 shows a processing flow of the treatment planning apparatus 201.

  In the treatment planning apparatus 201 of the present embodiment, the treatment plan creation processing flow is mainly composed of three steps in order to easily create a treatment plan while adjusting the balance between the dose restriction and the robustness of the dose distribution.

  The first step is a step of creating a database of a plurality of plan candidates in which the importance of the robust term is changed. When the operator instructs creation of plan candidate data (step S301), the treatment planning apparatus 201 starts creating a plan candidate database (step S401).

  When the creation of the plan candidate data in step S401 is completed, the operator proceeds to a step of adjusting the balance between the robust term and the dose constraint term while confirming the DVH or DVH band displayed on the display device 203. In this step, the treatment planning apparatus 201 calculates DVH and DVH bands in a balance between arbitrary robust terms and dose constraint terms based on the plan candidates registered in the database, and outputs them to the display device (step S402).

  The operator changes the balance between the robust term and the dose constraint term desired by the operator while confirming the DVH and DVH bands displayed in step S402 (step S302), and whether the DVH and DVH bands are in accordance with the target. Is determined (step S303). If it is determined that the target is achieved, the process proceeds to step S304. If it is determined that the target is not achieved, the process returns to step S301. After determining the balance between the robust term and the dose constraint term, the operator issues a final plan creation instruction (step S304).

  In the last step, the treatment planning apparatus 201 creates a treatment plan as a final plan based on the dose distribution determined by the operator or the importance of the robust term (step S403).

  Details of each step will be described below.

  First, the details of the plan candidate database creation flow in steps S301 and S401 described above will be described. FIG. 5 shows the flow of the procedure of the operator until the plan candidate database is created, and FIG. 6 shows the processing flow of the treatment planning apparatus 201 when creating the plan candidate data.

  First, a medical worker (engineer or doctor) who is an operator selects data (hereinafter referred to as CT data) related to a CT image for a treatment plan of a patient who creates a treatment plan (step S501). The selected CT data is three-dimensional data in which CT values are recorded for each small area called a voxel. The treatment planning apparatus 201 makes a treatment plan using this CT data. When the operator inputs patient information (patient ID) from the input device 202, the treatment planning device 201 starts creating patient treatment plan information corresponding to the patient ID.

  In the treatment planning device 201, first, the input device 202 outputs the input patient ID to the arithmetic processing device 205. The arithmetic processing unit 205 reads the target patient's CT data from the data server 208 based on the input patient ID. That is, the treatment planning apparatus 201 receives the CT data of the patient corresponding to the patient ID from the data server 208 through the network connected to the communication apparatus 207 and stores it in the memory 204. The treatment planning apparatus 201 creates a CT image for treatment planning based on the received CT data, and displays it on the display device 203 (step S601). The display device 203 displays an image in each slice (each layer) obtained by dividing the region including the affected part of the patient into a plurality of layers.

  While confirming the CT image displayed on the display device 203, the operator uses the input device 202 to input a region (target region) to be designated as a target for each slice of the CT image. The target area is an area that is determined to be irradiated with a particle beam, for example, including an area that the operator has determined to be a cancerous part of a patient.

  When the input of the target area for all slices is completed, the operator inputs an input end signal from the input device 202 (step S502). When receiving the input end signal, the treatment planning apparatus 201 stores and registers information on the target area in all slices in the memory 204. Information registered in the memory 204 is three-dimensional position information indicating the target area input by the operator. When there is an important organ in the vicinity of the target area where the irradiation dose should be suppressed as much as possible, or when there is another area that needs to be evaluated or controlled, the operator can select these based on the image information displayed on the display device 203. The position information of important organs is also input from the input device 202. The position information of the important organs and the like is stored and registered in the memory 204 as with the target area information. FIG. 7 shows an example in which the display device 203 displays the input target region 702, important organ 703, and other regions in an arbitrary slice (layer) 701 including the affected part, which is generated based on the CT data.

  Next, the operator designates irradiation parameters such as the irradiation direction and prescription dose (step S503). When performing irradiation from a plurality of directions, a plurality of angles are selected. In addition to this, the operator sets a prescription dose for each registered region.

  If the prescription dose is a target region 702 as shown in FIG. 7, the minimum value and maximum value of the dose to be received in the region are often input, but here the dose value to be irradiated to the target region 702 is set. Specify one. On the other hand, an allowable dose is often set for the important organ 703. In this example, an allowable dose is designated for the important organ 703.

  Subsequently, the operator sets an estimated value of uncertainty in planning a treatment for considering robustness (step S504). Uncertainties in planning treatment set in this step include CT image artifacts, range error due to CT value-water thickening conversion table error, setup error that occurs when positioning the patient, etc. It is. The operator uses the input device 202 to input the magnitude of the estimated uncertainty in mm units or%. The irradiation direction and prescription dose set as described above and the estimated value of uncertainty in planning the treatment plan are stored in the memory 204 of the treatment planning apparatus 201 (step S602).

  After registering the prescription dose, the operator sets the number of plans in the plan candidate database to be created (step S505). A plan candidate database is created according to the number of plans set here (steps S603 to S607).

  After the setting of the number of plans, when the operator gives a calculation instruction (step S506), the treatment planning apparatus 201 starts creating a plan candidate database.

  When the creation of the plan candidate database is started, first, the DVH band calculation unit 205B of the treatment planning apparatus 201 automatically sets the importance w of the robust term (step S603) and sets the objective function (step S604). As described above, the objective function for considering robustness is represented by the sum of the dose constraint term (formula (1)) and the robust term (formula (2)).

  Next, in the DVH band calculation unit 205B, the treatment planning apparatus 201 changes the importance w of the robust term of the objective function for each plan candidate to be created, and executes the irradiation amount optimization calculation (step S605).

  After completion of the optimization calculation, the DVH band calculation unit 205B stores the optimization calculation result in the data storage device 206 as plan candidate data (step S606). The data stored here includes the importance of the robust term, the objective function value of the robust term and the dose control term, the spot irradiation amount, and the dose evaluation point information (dose value and coordinate value) used to calculate the objective function. It is. When it is desired to include dose voxels in the stored data, it is necessary to perform dose calculation based on the spot irradiation amount calculated after the optimization calculation.

  Next, the treatment planning device 201 determines whether or not the calculation of the designated number of plan candidate data has been completed (step S607). When it is determined that the processing has ended, the processing is ended, and it is determined that the processing has not ended. If so, the process returns to step S603.

  Next, details of steps S302, S303, and S402 for determining whether the DVH and DVH bands are in accordance with the target will be described.

  In step S402, the DVH band calculation unit 205B of the treatment planning apparatus 201 performs DVH based on the DVH that changes according to the importance of the robust term instructed by the operator and the estimated uncertainty set in the previous steps S504 and S602. The band (DVH calculated under the error generation condition) is calculated using the candidate plan database created in step S 401 and displayed on the display device 203. An example of a state in which the DVH 802A and 802B and the DVH bands 803A and 803B are displayed on the display device 203 is shown in FIG.

  In the screen shown in FIG. 8, the operator can change the setting value of the importance level of the robust term by operating the slider 801A on the slider bar 801B using the input device 202. Accordingly, the DVH 802A and DVH band 803A of the target displayed, and the DVH 802B and DVH band 803B of the dangerous organ (OAR: Organ At Risk) are changed. Therefore, the operator can easily determine an appropriate balance between the robust term and the dose constraint term by operating the slider 801A on the slider bar 801B while observing the changes in the DVH 802A and 802B and the DVH bands 803A and 803B. It becomes possible.

  In this embodiment, the treatment planning apparatus 201 uses the flow shown in FIG. 9 to calculate and display the DVH and DVH bands for the importance of the robust term specified by the slider 801A on the slider bar 801B. This will be described below. FIG. 9 shows a flowchart.

  When the operator moves the slider 801A and designates the importance of an arbitrary robust term, the DVH band calculation unit 205B of the treatment planning apparatus 201 first selects a plan candidate having the importance of the robust term near the designated value as data. The plan candidate data group stored in the storage device 206 is searched for and stored in the memory 204 (step S901).

  Subsequently, the DVH band calculation unit 205B of the treatment planning apparatus 201 calculates a DVH band. As a method for calculating the DVH band, there are a method using dose voxel data stored as plan candidate data and a method using dose value data of dose evaluation points arranged in the region of interest. In the present embodiment, a case where a DVH band is calculated based on dose value data of dose evaluation points arranged in a region of interest will be described as an example.

  First, the DVH band calculation unit 205B of the treatment planning apparatus 201 determines the dose value data of the dose evaluation points arranged in the region of interest and the objective functions of the dose constraint term and the robust constraint term from the plan candidate data searched in step S901. A value is called (step S902).

  Next, using the distance in the objective function space between the called plan candidate and the importance of the robust term set by the operator, the dose value data at each dose evaluation point is interpolated to set any robust value set. Dose value data (interpolated dose value data) at the dose evaluation point with respect to the importance of the term is acquired (step S903).

  Next, the dose evaluation points are classified for each region of interest, a histogram is created from the interpolated dose value data of the dose evaluation points belonging to the region of interest, and DVH is created by accumulating this histogram from the high dose side. . A DVH band is created by executing this process for all error generation conditions (step S904).

  After creating the DVH band, the created DVH and DVH band are displayed on the display device 203 (step S905). Here, the DVH band to be displayed may display all DVH calculated for each error generation condition, or extract the maximum volume value and the minimum volume value of each dose value of DVH calculated for all error generation conditions. The two created lines (DVH) may be displayed.

  Also, as shown in FIG. 11, in the treatment planning apparatus 201 of the present embodiment, the DVH band calculation unit 205B of the arithmetic processing unit 205 moves the pointer 1101 onto the DVH bands 803A and 803B using the input device 202. Thus, an error generation condition corresponding to each calculation condition and a DVH difference value between a specified error generation condition and a condition without error can be displayed on the dialog 1102. FIG. 11 shows a state where a dialog corresponding to each DVH band is displayed.

  If the operator cannot obtain satisfactory DVH 802A and 802B only by adjusting the importance of the robust term, the DVH 802A and 802B are rescaled by the normalization process. Furthermore, in this rescaling, it is possible to use the DVH band (DVH when an error occurs) as DVH.

When such a normalization process is performed, the operator uses the input device 202 to set a target DVH in the standardization information setting unit 804 in FIG. 8 or FIG. ) and selects the one, etc.) what percent of the prescribed dose normalized method (D _95. Here, when the worst case DVH is selected, the DVH band calculation unit 205B of the treatment planning apparatus 201 searches the DVH band for the DVH under the error generation condition that is farthest from the normalization condition. For example, if you set the normalization condition that "the D ₉₅ to 95% of the prescribed dose" for DVH band targets are displayed in Figure 8, as DVH for calculating the scale of DVH, DVH band Select DVH at the bottom. Then, the scale amount is calculated using the selected DVH, and the DVH, DVH band and dose distribution are rescaled and displayed on the display device 203.

  Next, the details of the final treatment plan creation flow in steps S304 and S403 will be described.

  First, after the operator determines the balance between the robust term and the dose constraint term using the input device 202, the treatment planning device 201 stores the dose evaluation point data used for the DVH calculation in the memory 204. After data storage, the process proceeds to step S403 for creating a final treatment plan.

  The DVH and DVH bands displayed by the process of step S402 are calculated by interpolation from the dose distribution data of the plan candidate database stored in the data storage device 206, and the irradiation amount of each spot is actually calculated. I don't mean. For this reason, it is desirable to perform the process of step S403 which actually calculates the dose.

  Therefore, when the operator instructs execution of the final calculation, the main arithmetic unit 205A of the arithmetic processing unit 205 of the treatment planning apparatus 201 determines the irradiation amount of the spot that realizes the DVH and DVH bands displayed on the display unit 203. Calculated by optimization calculation.

  The method for defining the objective function for calculating the spot irradiation amount is a method for newly defining the objective function using the dose value at the dose evaluation point i used when calculating the DVH band in step S402. . FIG. 10 shows a processing flow.

  First, the main calculation unit 205A calls the interpolated dose value data stored in the memory 204 (step S1001), and sets the called dose value as a target dose at each dose evaluation point (step S1002).

  Subsequently, the main operation unit 205A sets an objective function used for optimization calculation (step S1003). In the dose distribution optimized for robustness, the dose distribution for each irradiation direction has characteristics such as the fact that a high dose area is not formed in front of the dangerous organ and the gradient of the dose distribution is gradual. . For this reason, the objective function is defined by the following equation (3) so as not to lose the characteristics of the distribution for each irradiation direction.

Here, P _i represents the interpolated dose value at the dose evaluation point i, and d _{i, f} and P _{i, f} represent the dose value at the dose evaluation point i in the irradiation direction f and the interpolated dose value.

  The main operation unit 205A performs optimization calculation using the equation (3) as an objective function (step S1004). As a result, the dose at each dose evaluation point can be brought close to the interpolated dose value, and the spot dose for obtaining the dose distribution desired by the operator can be calculated in step S402.

  When the spot irradiation amount is determined by the optimization calculation, the main calculation unit 205A calculates a dose distribution using the finally obtained spot position and the irradiation amount to each spot (step S1005). The calculation result is displayed on the display device 203 (step S1006). The operator can confirm on the display device 203 whether or not the designated dose is given to the target area without excess or deficiency.

  Next, the effect of the present embodiment will be described.

  As mentioned above, when creating a treatment plan for intensity-modulated proton therapy, it is important to balance the robustness of the dose distribution to the uncertainty during treatment planning and the achievement of the dose constraints set as a prescription. . Here, conventionally, if the robustness does not satisfy a desired condition, the robustness is evaluated again by changing the importance of the robust term by trial and error. For this reason, it is necessary to repeatedly calculate the dose distribution until a suitable balance between the achievement of dose restriction and the robustness is obtained, and it is not easy to create a treatment plan considering the robustness.

  On the other hand, in the treatment planning apparatus 201 for creating the treatment plan of the proton beam treatment according to the first embodiment of the present invention described above, the optimization calculation is performed by changing the importance w of the robust term, and the obtained dose distribution is obtained. Ask for. When the operator changes or sets the importance w of the robust term, the dose distribution calculated using the parameter closest to the set importance w of the robust term is searched, and the dose distribution at the set importance w is interpolated. Ask for. Then, DVHs 802A and 802B and DVH bands 803A and 803B are obtained from the obtained dose distribution and displayed on the display device 203.

  As a result, the operator can check the DVH 802A and 802B and the DVH bands 803A and 803B while changing the importance w of the robust term. Further, since the 802A and 802B and DVH bands 803A and 803B at the importance w of the robust term newly selected promptly by interpolation from the previously obtained dose distribution or the like are displayed, the degree of achievement of the appropriate dose constraint and the robustness Trial and error in obtaining the balance is much easier than in the past, and the creation of a treatment plan that takes into account the robustness against uncertainty during treatment is easier than in the past.

  Further, the arithmetic processing unit 205 calculates the dose distribution based on the interpolated DVHs 802A and 802B, so that the dose distribution can be calculated with higher accuracy in consideration of the robustness with respect to the uncertainty during the treatment. It becomes possible.

  Further, the display device 203 displays the generation conditions of the selected DVH bands 803A and 803B on the dialog 1102, so that the operator confirms the displayed information, so that an error generation condition in which the dose distribution is likely to deteriorate. Can be confirmed. This makes it possible to check whether the conditions that are likely to deteriorate are due to the range error or the setup error, which can be incorporated into judgments at the time of plan decision and response at the time of treatment, and is more robust. It is possible to create a treatment plan. For example, when a plan in which the dose distribution of a treatment plan is likely to deteriorate due to a setup error is created, it is possible to take measures such as carefully positioning the corresponding setup error in the direction of treatment.

  In addition, the arithmetic processing unit 205 normalizes the DVHs 802A and 802B based on the operator's instruction, and the display unit 203 displays the standardized DVHs 802A and 802B and the DVH bands 803A and 803B at that time. Thus, the DVH 802A and 802B that the operator is satisfied with and the DVH bands 803A and 803B at that time can be obtained more easily.

  Furthermore, the arithmetic processing unit 205 obtains DVH 802A and 802B and DVH bands 803A and 803B at that time that are easily understood by the operator by performing standardization processing with DVH bands 803A and 803B as DVH 802A and 802B. Can do.

  In addition, the data storage device 206 for storing the dose distribution in which the importance w of the robust term is calculated, which is calculated by the number specified in the arithmetic processing device 205, is further provided, thereby improving the processing speed of the interpolation calculation. Can contribute to the creation of a prompt treatment plan.

  Further, a slider bar 801B for adjusting the importance w of the robust term is displayed on the display device 203. By operating the input device 202 and moving the slider 801 on the slider bar 801B, the importance of the robust term is displayed. By changing and entering w, the operator can intuitively change and input the importance w of the robust term, and more easily create a treatment plan that takes into account the robustness against uncertainty during treatment. be able to.

  Further, in the treatment planning apparatus 201 for creating the treatment plan for the proton beam treatment according to the first embodiment of the present invention described above, the slider 801 on the slider bar 801B for adjusting the importance w of the robust term displayed on the display device 203. To change and input the importance w of the robust term, obtain the dose distribution at the set importance w, obtain DVH 802A, 802B and DVH bands 803A, 803B from the obtained dose distribution, and display device 203 is displayed.

  As a result, the operator can confirm DVH 802A, 802B and DVH bands 803A, 803B while intuitively changing the importance w of the robust term. Similarly, the degree of achievement of the appropriate dose constraint and the robustness can be confirmed. Trial and error in obtaining the balance is much easier than in the past, and the creation of a treatment plan that takes into account the robustness against uncertainty during treatment is easier than in the past.

<Example 2>
A treatment planning apparatus according to a second embodiment of the present invention and a treatment plan planning method using the treatment planning apparatus will be described with reference to FIG. The same components as those in FIGS. 2 to 11 are denoted by the same reference numerals, and description thereof is omitted.

  In the treatment planning apparatus of this embodiment, the standardization information setting unit 804 is not displayed on the display device 203, and the standardization processing function of the arithmetic processing unit 205 is omitted.

  In the main calculation unit 205A of this embodiment, there are two methods for defining an objective function for calculating the spot irradiation amount.

  The first method is the method described in the first embodiment, in which an objective function is newly defined using the dose value at the dose evaluation point i used when calculating the DVH band in step S402.

  The second method uses the formula (2). In the case of the method using the expression (2), it is necessary to estimate the weight value of the robust term from the weight of the plan candidate used when displaying the DVH band in step S402 and the objective function value.

  Other configurations / operations are substantially the same configurations / operations as those of the treatment planning apparatus of the first embodiment and the treatment planning method using the treatment planning apparatus, and the details are omitted.

  In the treatment planning apparatus according to the second embodiment of the present invention and the treatment planning method using the treatment planning apparatus, substantially the same effects as the treatment planning apparatus according to the first embodiment described above can be obtained.

<Others>
In addition, this invention is not limited to said Example, Various modifications are included. The above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

  For example, in the first and second embodiments, the example in which the treatment planning apparatus is applied to the intensity-modulated proton beam treatment has been described. However, the present invention is an intensity modulation that requires the creation of a treatment plan in consideration of robustness. The present invention can also be suitably applied to radiation therapy (X-ray therapy and particle beam therapy using heavy particle beams such as carbon ions). The treatment planning apparatus of the present invention can also be applied to the creation of a treatment plan by a treatment system using particle beams or X-rays that does not deviate in intensity.

  In addition, as a parameter related to robustness, in the above-described embodiment, the case where the importance of the robust term in the objective function in which the deviation from the prescription dose is quantified has been described, but the parameter related to robustness is In addition to the importance of the robust term, there is an objective function value of the robust term.

  Further, in the scanning irradiation method, after irradiating a predetermined amount of beam to a certain irradiation position (spot), the beam is once stopped, and after moving to the irradiation position to be irradiated next, irradiation is started again, and There is a raster system that does not stop the irradiation of the beam even while the irradiation position is moved. In the above-described embodiments, the spot scanning method has been described. However, the treatment planning apparatus of the present invention can be applied to the case of creating a treatment plan using a raster method or another irradiation method.

201 ... treatment planning device 202 ... input device (input unit)
203 ... Display device (display unit)
204 ... Memory 205 ... Arithmetic processing unit (arithmetic unit)
205A ... main calculation unit 205B ... DVH band calculation unit 206 ... data storage device (storage unit)
207 ... Communication device 208 ... Data server 701 ... CT data slice 702 ... Target region 703 ... Important organ 801A ... Slider (adjustment unit)
801B: Slider bar (adjustment unit) for adjusting the importance of robustness
802A, 802B ... DVH
803A, 803B ... DVH band 804 ... Standardized information setting unit 1101 ... Pointer 1102 ... Dialog

Claims (9)

A treatment planning apparatus for creating a radiation treatment treatment plan,
An input unit for changing and inputting parameters related to the robustness of the dose distribution of the radiation applied to the target;
Calculate the dose distribution by changing the parameters related to robustness by the specified number in advance, interpolate the dose distribution with the parameter input from the dose distribution closest to the parameter input in the input unit, and interpolate A calculation unit for calculating a DVH band which is a DVH and a DVH under a condition in which an error occurs from a dose distribution obtained by calculation;
A treatment planning apparatus comprising: a display unit that displays the DVH and the DVH band calculated by the calculation unit. The treatment planning device according to claim 1,
The said calculating part calculates the said dose distribution based on DVH by which the interpolation calculation was carried out. The treatment plan apparatus characterized by the above-mentioned. The treatment planning device according to claim 1,
The said display part displays the generation conditions of the selected DVH band. The treatment plan apparatus characterized by the above-mentioned. The treatment planning device according to claim 1,
The arithmetic unit normalizes the DVH based on an operator instruction,
The said display part displays DVH by which the normalization process was carried out, and the DVH band at that time. The treatment plan apparatus characterized by the above-mentioned. The treatment planning device according to claim 4, wherein
The said calculation part performs the normalization process which makes the said DVH band the said DVH. The treatment plan apparatus characterized by the above-mentioned. The treatment planning device according to claim 1,
A treatment planning apparatus, further comprising a storage unit that stores a dose distribution obtained by changing a parameter related to robustness calculated by the number specified by the calculation unit. The treatment planning device according to claim 1,
The display unit displays a slider bar for adjusting the parameter,
The treatment planning apparatus, wherein the parameter is changed / input by operating the input unit and moving a slider on the slider bar. The treatment planning device according to claim 1,
The parameter related to the robustness is an importance of a robust term in an objective function obtained by quantifying a deviation from a prescription dose or an objective function value of the robust term. An input unit for changing and inputting parameters related to the robustness of the dose distribution of the radiation applied to the target;
A calculation unit that calculates a dose distribution in the parameters input in the input unit, and calculates a DVH and a DVH band that is a DVH under a condition in which an error occurs from the calculated dose distribution;
A display unit for displaying the DVH and the DVH band calculated by the calculation unit;
The display unit displays an adjustment unit for changing and inputting the parameter,
The treatment planning apparatus, wherein the parameter is changed / input by operating the input unit and changing the adjustment unit.

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