JP2018134208A - Radiotherapy planning apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiotherapy planning apparatus for creating a treatment plan capable of appropriately selecting irradiation energy and reducing a time taken for irradiation by optimizing an irradiation amount.SOLUTION: In a treatment planning device 201, a reduction candidate for an energy layer is set based on an index set for each energy layer, and an objective function is defined for selectively reducing the number of irradiation spots or an irradiation amount of the reduction candidate. Using the objective function, the spot irradiation amount and the energy layer are optimized simultaneously.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a radiation therapy planning apparatus.

  In radiation therapy, a tumor is damaged by irradiating a target tumor cell with radiation. X-rays are the most widely used radiation for treatment, but demand for particle beams (charged particle beams) typified by proton beams and carbon beams with high dose concentration on the target is increasing.

  In radiotherapy, irradiating a dose designated to concentrate as much as possible on the tumor area as much as possible leads to an improvement in the therapeutic effect.

  In the 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 in the treatment apparatus and guided to an arbitrary position in the plane so as to fill the inside of the tumor, thereby giving a high dose only to the tumor area. It is. The scanning method does not basically require a patient-specific device, and has an advantage that various distributions can be formed.

  In order to realize this scanning method, a process of creating a treatment plan using a radiation treatment planning apparatus before irradiation is extremely important. The treatment planning apparatus is a computer having a function of simulating a dose distribution in a patient body by numerical calculation based on information in the patient body obtained from a CT image or the like. An operator (an operator who makes a treatment plan) refers to a calculation result output by the treatment planning apparatus, and irradiation conditions (also called a treatment plan) such as a direction of beam irradiation, beam energy, irradiation position, and dose. ). The general process will be briefly described below with reference to FIG. Details of this treatment plan creation process are described in detail in Patent Document 1.

  The operator first inputs and registers a target area to be irradiated with radiation (step S101). 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 where the radiation dose should be kept low.

  Subsequently, the operator sets irradiation conditions such as a target margin amount and a beam irradiation direction (step S102). The margin amount is set in order to irradiate a range (target region) slightly wider than the region necessary for covering the target tumor portion. By setting a margin, it is possible to ensure that a portion of a tumor to which a large dose is to be applied is reliably irradiated even if a small variation occurs in the tumor position or irradiation position.

  Next, the operator sets a related parameter of a target value (prescription dose) for irradiating each registered area (step S103). Prescription dose related parameters are set for registered target areas (targets) and important organs.

  For example, in the target area, a dose sufficient to kill the tumor is specified. On the other hand, regarding an important organ, an allowable dose is designated as a dose that can be tolerated by the organ. In addition to specifying the maximum dose to an important organ, a dose volume histogram (Dose-Volume Histogram, DVH) that is a dose evaluation index calculated from the volume information and dose distribution of a risk organ is included in the method of specifying an allowable dose. There is a method to specify using. Here, a method for specifying the maximum dose to an important organ will be described as an example.

  Subsequently, an irradiation condition for realizing a dose distribution satisfying the prescription dose is determined. The operator performs an optimization calculation for searching for the irradiation dose of the irradiation spot by using the treatment planning apparatus until a dose distribution considered to be appropriate is obtained (step S104). In order to efficiently determine the amount of irradiation of the spot, a method of optimizing the amount of irradiation of the spot by iterative calculation using an objective function that quantifies the deviation from the prescription dose is widely adopted.

  When the dose of the irradiation spot is calculated by iterative calculation, the treatment planning apparatus calculates a dose distribution based on the obtained irradiation position and dose of the spot and displays it on the screen (step S105). The operator evaluates the quality of the treatment plan by checking the displayed dose distribution or the dose evaluation index represented by DVH, and determines whether or not the treatment plan is used for the treatment (step S106). For example, if an area where a dose significantly different from the prescribed dose is confirmed and the operator determines that the quality of the created treatment plan is low, the process returns to step S102 described above, and irradiation conditions And re-create the treatment plan. On the other hand, when it is determined that it can be used for treatment, the process is terminated.

  In order to create a treatment plan with a small deviation from the prescribed dose (high quality), consider the detection lower limit (minimum MU value) of the dose monitor in the irradiation apparatus during the optimization calculation in step S105. Is reported to be important (see, for example, Non-Patent Documents 1 and 2, etc.).

JP 2011-217902 A

Zhu XR, Sahoo N, Zhang X, Robertson D, Li H, Choi S, Lee AK and Gillin MT, “Intensity modulated proton therapy treatment planning using single-field optimization: the impact of monitor unit constraints on plan quality”, Med. Phys. 37 1210-9 (2010). W. Cao et al., “Incorporating deliverable monitor unit constraints into spot intensity optimization in intensity-modulated proton therapy treatment”, Phys. Med. Biol. 58, 5113-25 (2013).

  As mentioned in Non-Patent Documents 1 and 2 above, when the spot irradiation amount is optimized without considering the minimum MU value, the irradiation amount of a spot having an irradiation amount equal to or lower than the minimum MU value is “rounded up. ”Or“ truncated ”and irradiated, causing dose distribution and DVH deterioration.

  Here, considering the profit side of the proton therapy facility, it is desirable to shorten the treatment time per patient so that the treatment throughput can be improved and many patients can be treated within a limited time. Moreover, there is an advantage that reducing the treatment time leads to a reduction in the burden on the patient.

  In the scanning irradiation method used in recent years in radiotherapy, with the same energy irradiation, two pairs of scanning electromagnets can be used to irradiate a beam at a high scanning speed of 2.0 m / s to 8.0 m / s. Is possible.

  On the other hand, regarding the energy change, it is necessary to accelerate and decelerate the beam every time the energy is changed, and it takes much time to change the energy as compared with the scanning by the scanning electromagnet. This energy change time is one of the factors that prolong treatment.

  When the irradiation amount is optimized in consideration of the restriction of the minimum MU value, the energy layer in which the irradiation spots are sparsely arranged increases in the energy layer on the low energy side where the irradiation amount becomes relatively small. Are known. If an irradiation plan can be created by efficiently selecting spots and energy layers for this shallow energy layer, the number of energy changes will be reduced by reducing the number of energy layers, and treatment time will be shortened. Is done. However, it has been difficult to determine the minimum energy layer that ensures the quality of the treatment plan.

  The present invention has been made in view of the above-described problems, and can create a treatment plan that can appropriately select irradiation energy, optimize the irradiation amount, and shorten the time required for irradiation. Provided is a radiotherapy planning apparatus capable of

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, a radiation treatment planning apparatus for creating treatment plan information for performing radiation treatment on an irradiation target, the treatment A computing device for creating plan information; and a display device for displaying the treatment plan information created by the computing device, wherein the computing device divides the irradiation target into a plurality of energy layers, and At least one energy layer reduction candidate is set based on an index set for each of a plurality of energy layers, or energy layer reduction candidates are set based on an input from an operator, and the number of irradiation spots or irradiation amount of the reduction candidates Defining an objective function that can be selectively reduced, and using the defined objective function to optimize the spot irradiation amount, That.

  According to the present invention, it is possible to create a treatment plan that can shorten the irradiation time.

It is a figure showing the flow until a treatment plan is drawn up when a general radiotherapy planning apparatus is used. It is explanatory drawing which shows the structure of the radiotherapy planning apparatus which is preferable one Embodiment of this invention. It is a figure showing the flow until a treatment plan is drawn up when using the radiotherapy planning apparatus of suitable one Embodiment of this invention. It is a figure explaining the input of the target area | region and important organ within the slice of CT data in the radiotherapy planning apparatus of this embodiment. It is a figure which shows an example of the screen which sets the parameter used for energy layer optimization in the radiotherapy planning apparatus of this embodiment. It is a figure showing the flow of a process at the time of the dose optimization calculation using the objective function which consists of a dose restriction | limiting term in the radiotherapy planning apparatus of this embodiment. It is a figure showing the flow of a process at the time of energy layer optimization in the radiotherapy planning apparatus of this embodiment. It is a figure which shows an example of the confirmation screen of the reduction effect of an energy layer in the radiotherapy planning apparatus of embodiment. It is a figure which shows an example of the selection screen of the energy layer reduction candidate in the radiotherapy planning apparatus of embodiment.

  An embodiment of the radiotherapy planning apparatus according to the present invention will be described with reference to FIGS. Initially, the whole structure of the radiotherapy planning apparatus of a present Example is demonstrated with reference to FIG. FIG. 2 shows the overall configuration of the radiotherapy planning apparatus according to this embodiment.

  In FIG. 2, a treatment planning device (radiotherapy planning device) 201 is a device for creating treatment plan information for performing radiation treatment on a target region (irradiation target) 402 (see FIG. 4). As illustrated in FIG. 2, the treatment planning apparatus 201 includes an input device 202, a display device 203, a memory 204, an arithmetic processing device (arithmetic device) 205, and a communication device 206.

  The input device 202 is a device for the operator to input various information such as a prescription dose for the target area 402 and execution, setting change, and termination of various processes when creating a treatment plan. is there.

  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.

  In particular, in the display device 203 of the present embodiment, the treatment plan information created by the arithmetic processing device 205 is displayed, and a selection screen for the operator to select and set energy layer reduction candidates to be described later (FIG. 8). , 9). In the displayed selection screen, information on energy layers before and after energy layer reduction is compared and displayed (see FIG. 8). The display device 203 displays an input screen (see FIG. 5) for the operator to input parameters used for energy layer optimization. Details of these will be described later.

  The memory 204 is a 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 performs arithmetic processing, determines irradiation conditions so that the dose distribution approaches the prescription dose input by the input unit 202, and creates treatment plan information, and performs optimization calculation of irradiation spots. This calculation unit 205A is implemented, and an energy layer optimization calculation unit 205B that performs optimization of the energy layer. The arithmetic processing device 205 is connected to the input device 202, the display device 203, the memory 204, and the communication device 206, and is connected to the data server 207 via a network. Specifically, the communication device 206 of the treatment planning device 201 is connected to the data server 207 via the network and exchanges data regarding the patient.

  As will be described in detail later, in the arithmetic processing unit 205 of the present embodiment, the target region 402 is divided into a plurality of energy layers by the energy layer optimization calculation unit 205B, and at least one energy is obtained from the plurality of divided energy layers. Perform layer optimization processing to reduce layers.

  In the layer optimization processing in the energy layer optimization calculation unit 205B, energy layer reduction candidates are set based on the index set for each of the plurality of energy layers, and the number of irradiation spots or the irradiation amount of the reduction candidates is selectively reduced. The objective function is defined, and the spot irradiation amount is calculated by the optimization calculation using the defined objective function. This energy layer reduction candidate is automatically determined based on a preset index such as the remaining rate of spots before and after optimization calculation in each energy layer.

  Further, the arithmetic processing unit 205 calculates an allowable change amount of the objective function value by the layer optimization process by the energy layer optimization calculating unit 205B, determines whether the allowable change amount satisfies a predetermined criterion, When it is determined that the predetermined standard is not satisfied, the importance of the energy reduction term is changed and the energy layer is optimized again.

  Next, referring to FIG. 3 to FIG. 8, the function of each device in the treatment planning device 201 regarding the flow of the planning of the particle beam treatment treatment by the scanning irradiation method using the radiation treatment planning device according to the present embodiment. • Explain the operation. 3 is a diagram showing the flow until a treatment plan is drawn up, FIG. 4 is a diagram for explaining the input of a target region and an important organ in a slice of CT data, and FIG. 5 is for setting parameters used for energy layer optimization. FIG. 6 is a diagram illustrating a flow of processing during dose optimization calculation using an objective function including a dose constraint term, and FIG. 7 is a diagram illustrating a flow of processing during energy layer optimization. FIG. 8 is a diagram showing an example of a confirmation screen for the energy layer reduction effect.

  The scanning irradiation method includes a spot scanning method in which the beam is stopped once after irradiating a predetermined amount of the beam to a certain irradiation position (spot), and after moving to the irradiation position to be irradiated next, irradiation is started again. There is a raster system that does not stop the irradiation of the beam even while the position is moving. Hereinafter, description will be made on the premise of a spot scanning method using particle beams. However, even in the case of the raster method, since it is necessary to set a plurality of irradiation positions in order to perform discrete calculation when obtaining the irradiation condition, the radiation treatment planning apparatus of the present invention is a treatment using the raster method. The present invention can also be suitably applied to the preparation of a treatment plan.

  In FIG. 3, when a treatment plan is started, the operator inputs a region to be specified for each slice of the CT image on a region input screen using a device such as a mouse corresponding to the input device 202. When input is completed in each slice, the operator registers the input area in the apparatus (step S301).

  FIG. 4 shows an example in which the operator inputs the target region 402 and the important organ 403 on the slice 401 having the CT image on the display device 203. If there are other areas that need to be evaluated and controlled, such as the presence of an important organ 403 whose irradiation dose is to be suppressed in the vicinity of the target area 402, the operator registers the positions of these important organs 403 and the like as well. The operator performs an instruction for registering the input target region 402 and important organ 403 to the treatment planning apparatus 201.

  By registering, these areas input by the operator are registered in the treatment planning apparatus 201 and stored in the memory 204 as three-dimensional position information.

  Next, the operator determines irradiation conditions (such as prescription dose and irradiation angle) for the registered target area (step S302). That is, the number of irradiation gates, the irradiation direction, the irradiation spot interval, and the margin amount are set based on the positions of the target region 402 and the important organ 403. There are also conditions in which the treatment planning apparatus 201 automatically determines not all irradiation conditions.

  Subsequently, the operator sets parameters used for energy layer optimization (step S303). As an example of parameter setting, a case where parameters are set using a setting screen as shown in FIG. 5 will be described.

  As shown in FIG. 5, the energy layer optimization parameters set by the operator include the initial value 501 of the importance of the energy layer reduction term, the allowable difference 502 of the objective function value due to the energy layer optimization, and the importance There is a maximum number of changes 503. Details of these parameters will be described later. The parameters set here are basically applied as common parameters in all irradiation directions.

  Next, the operator determines dose restrictions on the target region 402 and the important organ 403 to which the target itself or a margin is added (step S304). If the dose restriction is the target region 402, the prescription dose to be received in the region or the minimum value and the maximum value of the prescription dose are often input. On the other hand, an allowable dose is often set for the important organ 403. In this embodiment, the prescription dose to the target area 402 and the allowable dose of the important organ 403 are designated. The irradiation direction and prescription dose set as described above are stored in the memory 204 of the treatment planning apparatus.

  For convenience of explanation, the following description will be made on the assumption that the target dose p is given as a prescription dose only to the target region 402.

  When the setting of the prescription dose is completed, the treatment planning apparatus 201 executes the spot irradiation dose optimization calculation using the objective function including the dose restriction term by the calculation unit 205A according to the operator's instruction (step S305). Hereinafter, an operation flow of the treatment planning apparatus 201 at the time of optimization calculation of irradiation dose will be described with reference to FIG.

  In FIG. 6, first, the calculation unit 205A of the calculation processing device 205 of the treatment planning apparatus 201 arranges a point for evaluating dose (hereinafter referred to as a dose evaluation point) and an irradiation spot candidate in the target region (step S601).

  Subsequently, the main calculation unit 205A of the arithmetic processing unit 205 calculates a dose matrix A used for calculating the dose at each dose evaluation point (step S602). The dose matrix represents the contribution of the beam irradiated to each spot to the dose evaluation point, and is calculated based on the irradiation direction stored in the memory 204 and in-vivo information based on the CT image.

Subsequently, the main calculation unit 205A of the arithmetic processing unit 205 generates and defines an objective function F _general composed of a difference (dose constraint term) between the dose value and the prescription dose at each dose evaluation point (step S603). An objective function F _general consisting of a dose constraint term is expressed by the following equation (1).

Here, d _i represents the dose of each dose evaluation point.

Also, a vector d ^→ a of d _i elements (dimension is dose assessment score), the relationship of the vector x ^→ and the dose of each spot elements (dimension is the total number of spots) and dose matrix A has the formula It is represented by (2).

The smaller the value of the objective function F _general represented by the equation (1), the closer the dose at m dose evaluation points is to the target dose p.

Thereafter, the main processing unit 205A of the arithmetic processing unit 205 searches the irradiation amount of the spot that minimizes the objective function F _general by iterative calculation, and calculates the irradiation spot (step S604).

  When the search for the irradiation spot is completed, the calculation unit 205A of the arithmetic processing unit 205 stores the calculated irradiation spot in the memory 204 (step S605).

  Returning to FIG. 3, the energy layer optimization calculation unit 205B in the arithmetic processing unit 205 then performs optimization calculation of the spot irradiation amount in consideration of the number of energy layers for efficiently selecting the energy layer used for the treatment. The process transitions to (step S306). Having this energy layer optimization process is the greatest feature of the treatment planning apparatus of the present invention. The flow of energy layer optimization processing in the present embodiment will be described with reference to FIG.

In FIG. 7, when the energy layer optimization process is started, the energy layer optimization calculation unit 205 </ b> B first determines the spot number from the change in the number of spots for each energy layer before and after the optimization calculation performed in step S <b> 604. A remaining rate is calculated (step S701). k-th spot residual rate of energy layers, using the irradiation spot number n _k of radiation spots candidate number N _k and post-optimization calculation before optimization calculation of energy layers k, it is defined by the following equation.

Subsequently, the energy layer optimization calculation unit 205B sets energy layer reduction candidates based on the spot remaining rate calculated by Expression (3) (step S702). In the energy layer optimization calculation unit 205B of the treatment planning apparatus 201 of the present embodiment, energy layer reduction candidates are set according to the following three procedures.
1. Among all the energy layers, an energy layer included in 30% where the spot remaining rate is small is set as a reduction candidate.
2. The energy layer with the highest energy is excluded from the reduction candidates.
3. When adjacent energy layers exist in the reduction candidates, the energy layer having the larger remaining rate is excluded from the reduction candidates.

  After setting the energy layer reduction candidate, the energy layer optimization calculation unit 205B sets an objective function F for energy layer reduction (optimization) (step S703). The objective function F for energy layer reduction is defined by the following equation (4).

Here, the first term represents the dose constraint term (see equation (1)) set in step S603, and the second term represents the energy layer reduction term. S _k is a variable indicating whether or not the k-th energy layer is included in the reduction candidate selected in step S702. If it is included in the reduction candidate, S _k = 1, and if not included, S _{k k} = 0. Such By introducing the definition of variables S _k, it is possible to spot number in the energy layers included to reduce the candidate to define the objective function F to be reduced selectively. Further, X _{k, j} represents a dose of the j-th spot of the k-th energy layer, W _e represents the importance of the energy layer reduction section.

  Next, the energy layer optimization calculation unit 205B determines whether or not the number of changes of the energy layer reduction term is equal to or less than a set value (step S704). If it is determined that the value is less than or equal to the set value, the process proceeds to step S705. If it is determined that the value is greater than the set value, the process proceeds to step S709.

Then, the energy-layer optimization calculation unit 205B performs the setting by reading the initial value of importance W _e energy layer reduction section (step S705). The higher the larger value is set to the degree of importance W _e, solutions with an emphasis on reducing energy layer is obtained. The initial value of importance W _e, as described above, at step S303, the operator is set before treatment planning via the input device 202.

  Next, the energy layer optimization calculation unit 205B performs optimization calculation in consideration of the number of energy layers using the objective function defined in step S703 (step S706).

  After completion of the optimization calculation, the energy layer optimization calculation unit 205B determines whether or not an energy layer in which the number of irradiation spots does not remain is derived by the energy layer optimization process in the previous step S706 (step S707). If it is determined as a result of the optimization calculation that an energy layer having no number of irradiation spots has been derived, the energy layer optimization calculation unit 205B deletes the energy layer having no irradiation spots from the irradiation spot candidates set in step S601. Then (step S708), an optimization calculation of the spot irradiation amount is performed again using the objective function including only the dose constraint term (step S710).

  On the other hand, if it is determined in step S707 that an energy layer having no irradiation spot has not been derived, the irradiation spot information optimized by the objective function including only the dose constraint term stored in step S605 is used as the spot irradiation amount. Set (step S709), the optimization of the spot irradiation amount is completed.

  When the energy layer is reduced and the irradiation plan is created, the quality of the plan may be deteriorated as compared to before the energy layer is reduced. In order to prevent this, the energy layer optimization calculation unit 205B determines whether the quality of the created plan is acceptable after the optimization calculation in step S710 again (step S711). In step S711, whether the plan quality is acceptable or not is determined using the amount of change in the objective function value before and after the energy layer reduction. The determination formula is shown in Formula (5).

Here, F _{general, R} is the result of performing optimization calculation using the irradiation spot candidates after the energy layer reduction (result of step S708), and the convergence value of the objective function according to the equation (1) obtained is expressed as F _{general, “base”} represents the convergence value of the objective function of the equation (1) obtained as a result of the optimization calculation using the irradiation spot candidate before the energy layer reduction (result of step S604). Further, θ represents an allowable change amount of the objective function value by energy layer optimization. The allowable change amount θ can be set by the operator via the input device 202 before creating a treatment plan in step S303.

If it is determined that Expression (5) is not satisfied and the change in the convergence value of the objective function is not acceptable, the energy layer optimization calculation unit 205B moves the process to step S712, and the importance W _{e of the} energy reduction term Is decreased (step S712), the process returns to step S704, and the energy layer is optimized again (steps S704 to S711). If Step S704 to Step S711 are repeated until Expression (5) is satisfied and Expression (5) is satisfied, optimization of the spot irradiation amount ends.

Or, if the number of changes of importance W _e of energy reduction section exceeds the maximum number of changes set in step S303 (if the number of changes in energy layer reduction term is determined to be greater than the set value in step S704), the In order to prevent the energy layer optimization from taking more time than necessary, only the dose constraint term saved in step S605 as in the case where it is determined in step S707 that an energy layer without an irradiation spot is not derived. The irradiation spot information optimized by the objective function consisting of is set as the spot irradiation amount (step S709), and the optimization of the spot irradiation amount is finished.

  Returning to FIG. 3, when the spot irradiation amount is determined, the treatment planning device 201 uses the main calculation unit 205 </ b> A of the arithmetic processing unit 205 to use the finally obtained spot position and the irradiation amount to each spot, A dose distribution is calculated (step S307).

  Next, the treatment planning apparatus 201 calculates the DVH value using the main calculation unit 205A of the arithmetic processing unit 205, and displays the calculated result on the display unit 203. The operator confirms on the display device 203 whether or not the designated dose is given to the target area without excess or deficiency (step S308). A histogram called DVH (Dose Volume Histogram) is also widely used for confirming the dose distribution to the target region 402.

  The operator analyzes the dose distribution result using the dose distribution or DVH displayed on the display device 203, and determines whether or not the dose distribution satisfies a target condition (step S309). When it is determined that the target is sufficiently satisfied and the desired result is obtained, the process proceeds to step S310, and the obtained irradiation condition is output and stored in the data server 307 through the network (step S310), the planning of the treatment plan ends. On the other hand, when it is determined that the target is not satisfied and the distribution is not desirable, the process returns to step S302, and the irradiation condition is reset. The setting to be corrected includes changing the irradiation direction and the spot interval. When the condition is changed, the treatment planning apparatus 201 calculates the spot and the dose according to the operator's instruction (Steps S303 to S308), and the new dose distribution result is displayed on the display device 203, and the correction is repeated until the target is satisfied. .

  In step S309, a confirmation screen can be displayed in order to confirm the energy layer reduction effect for each irradiation direction. An example of a confirmation screen for energy layer reduction terms is shown in FIG. The left side in FIG. 8 shows information before energy layer optimization (the state optimized in step S604), and the right side in FIG. 8 shows information after energy layer optimization.

  In FIG. 8, the confirmation screen displayed on the display device 203 includes three display units: an irradiation direction display unit 801, an energy layer number display unit 802, and an energy layer information display unit 803.

  First, the operator operates the input device 202 to select an irradiation direction for which the energy layer reduction effect is to be confirmed on the irradiation direction display unit 801. The energy layer information display unit 803 displays the total irradiation MU value of each energy layer in a table format. Here, the energy layer whose irradiation amount MU value is 0 is grayed out and items are displayed.

  Further, the leftmost column in the table on the right side of the energy layer information display unit 803 is a column indicating whether or not the energy layer was optimized at step S702, and a check mark is displayed on the energy layer that was a candidate. . By looking at this column, the operator can confirm at what rate the energy layer can be reduced among the energy layers set as reduction candidates.

  In addition, by referring to the energy layer number display unit 802 before and after the optimization process, it is possible to confirm how many layers have been deleted by the energy layer optimization process.

  Up to this point, we have explained the case of calculating automatically based on the remaining rate of spots before and after optimization calculation as a method for selecting energy layer reduction candidates. However, energy layers that you want to reduce or do not want to reduce In order to cope with the case where there is, it is also possible for the operator to selectively set energy layer reduction candidates. Hereinafter, the embodiment will be described with reference to FIG. FIG. 9 is a diagram illustrating an example of a selection screen for energy layer reduction candidates.

  The energy layer reduction candidate selection screen shown in FIG. 9 is displayed on the display device 203 of the treatment planning apparatus 201 after step S305.

  The operator uses FIG. 9 to select energy layer reduction candidates for each irradiation direction. First, using the irradiation direction display unit 901, an irradiation direction for setting energy layer reduction candidates is selected. When the irradiation direction is selected, the energy layer information is displayed in a table format on the energy layer information display unit 902 based on the result of step S305. The leftmost column of this table is a column indicating whether or not it is a reduction candidate, as in FIG. The operator can arbitrarily set a reduction candidate by using the input device 202 to set whether or not to check for each energy layer. After selecting reduction candidates for all the irradiation directions, the optimization calculation execution button 903 is pressed to execute the processes in and after step S306, and the energy layer is optimized.

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

  The treatment planning apparatus 201 that creates treatment plan information for performing radiation therapy on the target region 402 of the above-described embodiment is created by the arithmetic processing apparatus 205 that creates treatment plan information and the arithmetic processing apparatus 205. A display device 203 that displays treatment plan information, and the arithmetic processing device 205 divides the target region 402 into a plurality of energy layers, and reduces the energy layer based on an index set for each of the divided energy layers. Set at least one candidate, or set energy layer reduction candidates based on operator input, and define and define an objective function that selectively reduces the number of irradiation spots or dose of reduction candidates The spot irradiation dose is optimized and calculated using the objective function (layer optimization processing).

  According to the treatment planning apparatus 201 that performs such layer optimization processing, energy layer reduction candidates are set based on an index set for each energy layer or an operator's input, and the number of irradiation spots or the amount of irradiation of the reduction candidates Since the optimization calculation is performed with an objective function that selectively reduces the number of possible energy layers while ensuring the quality of the treatment plan, the number of energy changes during irradiation can be reduced. Reduced treatment plans can be created. For this reason, the irradiation dose can be optimized, the time required for irradiation can be shortened, and a therapeutic effect can be sufficiently ensured.

  In addition, since the operator has the input device 202 for inputting at least one of the prescription dose and the irradiation condition for the target region 402, energy layer reduction candidates that more reflect the operator's intention can be set. .

  Furthermore, the processing unit 205 uses an objective function that selectively reduces the number of irradiation spots or doses of reduction candidates from the treatment plan information calculated based on the prescription dose or the irradiation conditions input by the operator. Since the treatment plan information calculated after the optimization calculation has a smaller number of energy layers, it is possible to create a treatment plan in which the number of energy changes during radiation irradiation is reduced.

  Further, the display device 203 displays a selection screen for the operator to select and set energy layer reduction candidates, so that the operator of the treatment planning device 201 confirms the energy layer reduction effect for each irradiation direction. can do. Therefore, it is possible to easily grasp whether or not the quality of the treatment plan is ensured, and it is possible to perform irradiation with a high treatment effect in a short time.

  Further, the display device 203 displays the energy layer information before and after the energy layer reduction on the selection screen, so that the operator of the treatment planning device 201 can easily confirm the energy layer reduction effect for each irradiation direction. be able to.

  In addition, the arithmetic processing unit 205 automatically determines energy layer reduction candidates based on a preset index, so that the operator of the treatment planning apparatus 201 can perform appropriate energy layer reduction candidates without repeating trial and error. The time required for creating a treatment plan can be shortened.

  Furthermore, the preset index is the remaining rate of spots before and after optimization calculation in each energy layer, so that an energy layer that can ensure the quality of the treatment plan is selected more efficiently, and the treatment effect It is possible to make a significant contribution by carrying out high irradiation in a short time.

Further, the arithmetic processing unit 205 calculates an allowable change amount θ of the objective function value by the layer optimization process, determines whether the allowable change amount θ satisfies a predetermined criterion, and does not satisfy the predetermined criterion. when it is determined in by changing the severity W _e of energy reduction section, by implementing the optimization again energy layers, it is possible to ensure the quality of more reliably treatment plan.

Furthermore, the arithmetic processing device 205 is set in advance, or set by the operator, by performing optimization calculation based on the upper limit of the number of changes severity W _e, the energy-layer optimization process unnecessarily This can be suppressed, and the time required for creating a treatment plan can be shortened.

The display device 203, the upper limit of the degree of importance W number of changes _e, the initial value of importance W _e, by displaying the setting screen for setting the allowable change theta, quality more easily treatment plan operator It is possible to achieve both the security of this and the shortening of the time required for preparing the treatment plan.

<Others>
In addition, this invention is not restricted to said Example, A various deformation | transformation and application are possible. 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.

201 ... treatment planning device 202 ... input device 203 ... display device 204 ... memory 205 ... arithmetic processing unit 205A ... main arithmetic unit 205B ... energy layer optimization arithmetic unit 206 ... communication device 207 ... data server 401 ... CT data slice 402 ... Target region 403 ... Important organ 501 ... Initial value input part 502 of energy layer reduction term input part ... Permissible value of objective function change amount input part 503 ... Maximum number of changes of energy layer reduction term 801 ... Energy layer reduction effect confirmation Screen irradiation direction display unit 802 ... Energy layer reduction effect confirmation screen energy layer number display unit 803 ... Energy layer reduction effect confirmation screen energy layer information display unit 901 ... Energy layer reduction candidate selection screen irradiation direction display unit 902 ... Energy layer reduction candidate selection image Optimization calculation button of reducing candidate selection screen energy layer information display unit 903 ... energy Layer

Claims (10)

A radiotherapy planning apparatus for creating treatment plan information for performing radiotherapy on an irradiation target,
A computing device for creating treatment plan information;
A display device for displaying the treatment plan information created by the arithmetic device,
The arithmetic unit divides the irradiation target into a plurality of energy layers, and sets at least one energy layer reduction candidate based on an index set for each of the divided energy layers, or an operator input Based on the above, energy layer reduction candidates are set, an objective function that selectively reduces the number of irradiation spots or the irradiation amount of the reduction candidates is defined, and the spot irradiation amount is optimized using the defined objective function A radiation therapy planning device characterized by calculating. In the radiotherapy planning apparatus according to claim 1,
A radiotherapy planning apparatus, comprising: an input device through which an operator inputs at least one of a prescription dose or an irradiation condition for the irradiation target. In the radiotherapy planning device according to claim 2,
Optimal using an objective function such that the number of irradiation spots or dose of the reduction candidate is selectively reduced from the treatment plan information calculated based on the prescription dose or irradiation condition input by the operator by the arithmetic unit The radiotherapy planning apparatus characterized in that the treatment plan information calculated after the computerization calculation has a smaller number of energy layers. In the radiotherapy planning apparatus according to claim 1,
The display apparatus displays a selection screen for an operator to select and set the energy layer reduction candidates. In the radiotherapy planning device according to claim 4,
The said display apparatus compares and displays the information of the energy layer before and behind energy layer reduction in the said selection screen. The radiotherapy planning apparatus characterized by the above-mentioned. In the radiotherapy planning apparatus according to claim 1,
The said arithmetic unit determines the reduction candidate of the said energy layer automatically based on the parameter | index set beforehand. The radiotherapy planning apparatus characterized by the above-mentioned. In the radiotherapy planning device according to claim 6,
The pre-set index is a remaining rate of spots before and after optimization calculation in each energy layer. In the radiotherapy planning apparatus according to claim 1,
When the arithmetic device calculates an allowable change amount of the objective function value by the layer optimization process, determines whether the allowable change amount satisfies a predetermined criterion, and determines that the predetermined criterion is not satisfied Is a radiotherapy planning device characterized by changing the importance of the energy reduction term and optimizing the energy layer again. The radiotherapy planning apparatus according to claim 8, wherein
The said arithmetic unit performs optimization calculation based on the upper limit of the frequency | count of the change of the said importance set beforehand or set by the operator. The radiotherapy planning apparatus characterized by the above-mentioned. In the radiotherapy planning device according to claim 9,
The display device displays a setting screen for setting an upper limit of the number of changes of the importance, an initial value of the importance, and the allowable change amount.

Images