Method for calculating delivery values for a radiotherapy plan

Abstract

Disclosed herein is a method of calculating a delivery value for delivering an arc segment between two control points of a treatment plan, the treatment plan specifying MLC leaf positions at each control point, the method comprising: calculating an arc segment delivery time for each of a plurality of components using a default delivery value, wherein one of the components is MLC leaf motion; selecting the component that indicates the longest arc segment delivery time as a time limiting component; if the time limiting component is MLC leaf motion: providing an optimized MLC delivery value; and if a predetermined condition is met, setting the time limiting component delivery value to the optimized delivery value, and outputting the time limiting component delivery value.

Description

Technical Field

[0001] This disclosure relates to a method for treatment control planning, a treatment control computer, and a radiotherapy apparatus including the treatment control computer. Background Technology

[0002] Radiation therapy involves generating a beam of ionizing radiation, typically X-rays, electron beams, or other subatomic particles. Using a linear accelerator, the tumor is irradiated with these high-energy particles (e.g., electrons, protons, ions, etc.). The setup and dosage of the radiation beam must be precisely controlled to maximize the radiation dose to the patient's cancer cells and minimize it to the patient's healthy cells, as this improves treatment efficiency and reduces side effects.

[0003] In radiotherapy equipment, beam shaping devices can be used to constrain the radiation beam. These devices define a variable-shape aperture to collimate the radiation beam into a selected cross-sectional shape. Beam shaping devices can be formed by a combination of diaphragms and multi-leaf collimators (MLCs). These can be adjusted during treatment to produce a beam whose cross-section dynamically changes as the beam rotates around the patient.

[0004] A radiation source and a multi-leaf collimator are attached to a gantry that rotates around the patient in a plane orthogonal to the axis of rotation. The result is that the target remains within the beam at all times, but the area directly surrounding the target is only briefly irradiated by the beam during a portion of its rotation. Delivering radiation to the patient from multiple angles maximizes the radiation dose to cancer cells and minimizes the radiation dose to the patient's healthy cells.

[0005] Treatment plans are developed based on delivering specific doses to the target patient.

[0006] Different types of radiotherapy techniques alter different parameters of the beam. Intensity-modulated radiotherapy involves techniques that modify the beam delivered to the patient. Controllable elements include the position of the blades of a multi-leaf collimator, the angle of the gantry, the dose rate of radiation emitted from the source, and the rotational speed of the source.

[0007] The treatment plan defines the blade position, rotation angle, and dose (which is determined by the bench rotation speed or the dose rate of the source). The blade motion, bench motion, and dose rate can be adjusted to deliver the treatment plan. Summary of the Invention

[0008] Various aspects and features of this disclosure are described in the appended claims.

[0009] According to one aspect, a method is provided for calculating a delivery value for delivering an arc segment between two control points in a treatment plan, the treatment plan specifying an MLC blade position at each control point, the method comprising: calculating an arc segment delivery time for each of a plurality of components, one of which is an MLC blade motion, using a default delivery value; selecting the component indicating the longest arc segment delivery time as a time-limited component; if the time-limited component is an MLC blade motion: providing an optimized MLC delivery value; and if predetermined conditions are met, setting the time-limited component delivery value to the optimized delivery value, and outputting the determined delivery value.

[0010] Optionally, the method further includes: using the optimized delivery value to calculate an optimized arc delivery time; and comparing the optimized arc time with the longest arc delivery time to determine whether a predetermined condition is met.

[0011] Optionally, the method further includes: if the optimized arc delivery time is longer than the longest arc delivery time, then setting the time limit delivery value to the default delivery value; if the optimized arc delivery time is shorter than the longest arc delivery time, then setting the time limit delivery value to the optimized delivery value.

[0012] Optionally, the method further includes providing an optimized delivery value, including: selecting MLC parameters for arc segment delivery; determining whether the parameters meet predetermined requirements; and if the predetermined requirements are met, determining an optimized delivery value.

[0013] Optionally, the method further includes determining an optimized delivery value, including selecting an optimized delivery value from a lookup table.

[0014] Optionally, the method also includes MLC parameters, which include one or more of the following: thermal load, current load, maximum rpm, motor / gearbox constraints, relative blade proximity and relative motion amplitude, gravity direction relative to blade motion, number of blades in motion, tumor tracking requirements, and amplitude of the tracking motion vector.

[0015] Optionally, the method further includes a treatment plan, which includes the bench location at each control point and the dose for each arc segment.

[0016] Optionally, the method further includes setting the time-limited component delivery value to the corresponding default delivery value if the limiting component is not an MLC.

[0017] Optionally, the method further includes: once the time-limited component delivery value has been set, calculating a reduced delivery value for each remaining component to match the arc delivery time of the time-limited component.

[0018] Optionally, the method also includes a default delivery value, which includes at least one of the following: maximum blade velocity; maximum blade acceleration; maximum gantry rotation speed; maximum gantry rotation acceleration; and maximum dose rate.

[0019] Optionally, the method may also include repeating the method for each of the multiple arcs of the treatment plan.

[0020] Optionally, the method further includes outputting the determined delivery value to a controller configured to control the radiotherapy device to deliver a treatment plan based on the output delivery value.

[0021] Optionally, the method includes: outputting the determined delivery value to a radiotherapy device.

[0022] Optionally, the method further includes controlling the radiotherapy device to operate the components at their respective delivery values.

[0023] Optionally, the method further includes delivering a first arc segment and a second arc segment, wherein the radiation between the first arc segment and the second arc segment is uninterrupted.

[0024] Optionally, the method further includes providing a set of optimized MLC delivery values, including: determining whether each of a plurality of parameters is below a threshold; and if all delivery parameters are below the corresponding threshold, outputting optimized delivery values ​​from a lookup table.

[0025] According to one aspect, a computer-readable medium is provided, comprising computer-executable instructions configured to perform the method.

[0026] According to one aspect, a radiotherapy apparatus is provided, the radiotherapy apparatus comprising a source capable of emitting a therapeutic radiation beam along a beam axis, a multi-leaf collimator arranged to collimate the beam into a desired shape, wherein the source is rotatable about a rotation axis substantially orthogonal to and intersecting the beam axis to describe an arc along the axis, and a planning computer including computer-readable instructions configured to perform the method when executed by the planning computer.

[0027] Optionally, the method further includes a radiotherapy device, the radiotherapy device including a controller configured to control the radiotherapy device to deliver a treatment plan based on output delivery values ​​from a planning computer. Attached Figure Description

[0028] The specific embodiments are described below by way of example and with reference to the accompanying drawings, wherein:

[0029] Figure 1 The plan computer is shown;

[0030] Figure 2 A method for calculating the delivery value of the radiation dose to be delivered based on the treatment plan is shown;

[0031] Figure 3 This demonstrates a method for optimizing MLC delivery values; and

[0032] Figure 4 A method for providing optimized delivery values ​​is shown. Detailed Implementation

[0033] Overview

[0034] The speed and acceleration of the MLC blades are limited to "default maximum values". These maximum values ​​are conservative and can be obtained under any operating conditions (i.e., all blades are driven at maximum speed simultaneously).

[0035] If operating conditions permit, optimization can be performed, and the MLC can be driven at a higher speed than the "default maximum value" without compromising it. If the MLC is a "time-constrained component," treatment time can be reduced through optimized values. During the delivery planning phase, parameters related to the MLC are analyzed to determine whether optimized values ​​can be used instead of the default maximum value.

[0036] Detailed description of specific exemplary embodiments

[0037] This section describes the methods for creating a treatment delivery plan.

[0038] As mentioned above, in radiotherapy, radiation is directed to the patient's cancerous area (e.g., tumor). A plan is provided to deliver the correct radiation dose to the patient, targeting the target cells while minimizing the dose to adjacent healthy cells.

[0039] The radiation dose to be delivered to the patient during the treatment phase is provided to the planning computer in the form of a desired dose distribution 10. The planning computer 08 may include a treatment planning computer 12 and a delivery planning computer 16. Alternatively, the treatment planning computer 12 and the delivery planning computer 16 may be separate entities, collectively referred to as planning computer 08. The dose distribution includes a three-dimensional graph showing areas that must receive a specified radiation dose (e.g., the lesion itself), areas where the dose should be minimized as much as possible, and areas that receive essentially no radiation or must be delivered a dose less than the specified dose (e.g., sensitive structures and vital organs).

[0040] The treatment planning computer 12 receives the dose distribution 10. The treatment planning computer determines the treatment plan 14 by calculating the necessary rotations, the dose rate (the dose is drawn relative to the motion axis, so it is the motion velocity where the dose rate is actually defined, where the dose delivered at a specific distance is defined), and the collimator shape used to deliver the dose distribution to the patient.

[0041] The treatment planning computer 12 creates the desired treatment plan based on the sequence of control points. Each "control point" defines the position of the gantry, the dose delivered between that control point and the next (or previous) control point, and the MLC shape at that control point. Each consecutive pair of control points defines an arc segment (between them). Control points could (theoretically) be spaced systematically along the entire arc. However, relatively weak processing power means there is little benefit in doing so, and control points are therefore typically spaced regularly along the arc, for example, every degree, every few degrees, or every fraction of a degree.

[0042] Between the nth and (n+1)th control points, the stage is moved from the position of the nth control point to the position of the (n+1)th control point by combining a rotational speed and dose rate to deliver the desired dose, while simultaneously moving the MLC blades so that when the stage is at the (n+1)th control point, the blades are in the correct position at that point. Typically, the MLC blades will be moved at a rate that ensures the distance they move is always linearly related to the dose delivered in the arc segment. This process is then repeated for the arc segment between the (n+1)th and (n+2)th control points, and so on, until treatment is complete.

[0043] Once the treatment plan 14 has been created, it must be converted into a set of bench motions, dose rates, and MLC motions to deliver the treatment plan, taking into account the physical limitations of the radiotherapy equipment. This is done by the delivery plan computer 16.

[0044] The delivery planning computer 16 receives the treatment plan 14 from the treatment planning computer 12. The delivery planning computer 16 creates a treatment delivery plan 18 based on the treatment plan 14 and the capabilities and constraints of the radiotherapy equipment in question.

[0045] The delivery planning computer 16 includes or has access to a set of machine constraints on the radiotherapy apparatus. The machine constraints detail the properties of the apparatus, including the geometry of the beam and collimator, maximum dose rate, and maximum rotational speed. An algorithm is then applied to generate a treatment delivery plan 18, which includes detailed instructions regarding the required rotational speed, dose rate, blade speed, and their variations over time. For each arc segment, the output from the delivery planning computer 16 is a calculated value of the dose rate, gantry motion, and MLC motion to deliver the treatment plan in combination. This is the treatment delivery plan 18.

[0046] Delivery values ​​are values ​​used by components of a radiotherapy device to deliver treatment plans. The components of the radiotherapy device are controlled based on these delivery values.

[0047] Treatment delivery plan 18 is transmitted to the control system 20 of the radiotherapy apparatus. The control system includes separate local control units 22, 24, and 26, each controlling various components of the radiotherapy apparatus. In this case, these components are an MLC controller 22 (e.g., multiple blade actuators), a gantry controller 24 (e.g., a gantry rotation actuator), and a radiation controller 26 (e.g., a dose rate controller). Relevant portions of the delivery plan 18 (e.g., relevant delivery values) are transmitted to the local control units. The local control units then operate the various components according to the delivery values, thereby delivering the desired dose distribution. Generally, one such control unit exists for each component, although some functions may be combined into a single unit for closely related geometric components (e.g., MLC blades). This unit receives approximately the entire treatment delivery plan (or at least the portion related to the plan) at the start of treatment. This plan specifies the movement of the geometric units required during treatment.

[0048] Figure 1 The computer shown may physically be one or more computers, but is considered herein as a distinct functional element of the system. This treatment plan can be implemented on existing radiotherapy equipment. This disclosure relates to control equipment and treatment planning equipment; the actual radiator and the means of driving the radiator, its MLC, and other systems that can remain unchanged during use. Therefore, treatment delivery plans can be reused on existing radiotherapy equipment.

[0049] constraint

[0050] As described above, the delivery planning computer creates a treatment delivery plan based on the individual capabilities and constraints of the radiotherapy equipment under discussion. The constraints used in determining delivery values ​​are referred to herein as "default values".

[0051] Default values ​​are selected to ensure treatment plans can be delivered under all operating conditions. Default values ​​are not set to absolute maximum values ​​for the component, but rather to values ​​achievable over the treatment duration. Default values ​​for the MLC include maximum blade velocity and maximum acceleration. Default values ​​for the bench actuator include maximum rotational speed and rotational acceleration. The default value for the radiation source is the maximum dose rate. In some implementations, jerk parameters (the first time derivative of acceleration and the second time derivative of velocity) are also considered, with the default value being the maximum jerk. However, in low-inertia systems, jerk may be disregarded.

[0052] The default values ​​for maximum blade speed and acceleration are conservative because these values ​​are chosen to be lower than the absolute maximum blade speed and acceleration. This is because the calculated default values ​​are available in all cases. For example, in the following cases:

[0053] - Each blade of the multi-leaf collimator is driven simultaneously

[0054] - The blades continue to drive at maximum speed

[0055] - The blades are driven by gravity.

[0056] Furthermore, a percentage of the blade's available speed must be maintained for target tracking so that the blade can always accelerate if tracking is required. In other words, a certain amount of speed should be reserved to avoid positional errors.

[0057] A maximum speed is introduced to protect the MLC and ensure tracing is possible. However, this value is based on a "worst-case" scenario and is therefore lower than what is needed in most cases.

[0058] Therefore, in many cases, the blades can be driven faster than the default value. That is, depending on the conditions of a specific part of the treatment, the blades can be driven faster than reflected in the constraints utilized by the delivery plan computer when preparing to process the delivery plan. If the processing time of the treatment plan delivery is limited by the multi-leaf collimator, a more detailed model of the multi-leaf collimator can be used to reduce the delivery length.

[0059] The purpose of the invention disclosed herein is to reduce delivery time, which is important for dispensing efficiency and to prevent organ movement between imaging and completion of irradiation.

[0060] Figure 2

[0061] Figure 2 A method for determining delivery values ​​for a treatment delivery plan is shown. This method is performed by a delivery plan computer (e.g., delivery plan computer 16).

[0062] In this disclosure, steps are introduced to determine whether MLC is a time-constrained factor in the treatment delivery plan. If MLC is a time-constrained factor, a delivery analysis is performed to determine whether optimization is possible.

[0063] In step 100, the delivery planning computer 16 receives the treatment plan 14 from the treatment planning computer 12. The treatment plan includes a sequence of control points as described above. Each control point defines the position of the gantry, the dose to be delivered between that control point and the next (or previous) control point, and the shape of the MLC at that control point. Each consecutive pair of control points defines an arc segment (between them). The treatment plan is delivered using a radiotherapy apparatus having multiple components or machine parts. In this embodiment, three components are included: a multi-leaf collimator; a gantry; and a radiation source.

[0064] In other implementations, the method disclosed herein is used when only the two components mentioned above exist or are considered.

[0065] For each segment of the delivery plan, complete steps 102 to 110.

[0066] In step 102, the computer uses default values ​​to calculate the time required for each component to meet the requirements defined for that arc segment. This is the minimum arc segment delivery time for each of the three components, and the fastest possible delivery time that each component can deliver the arc segment requirement using constraints.

[0067] This includes:

[0068] • For each blade of the MLC, calculate the time required to move the blade between control point positions using the maximum blade velocity and acceleration.

[0069] • For the test bench, use the maximum rotational speed and maximum rotational acceleration to calculate the time required to rotate the test bench between control point angles.

[0070] • For radiation sources, calculate the time required to deliver the dose in the delivery arc using the maximum dose rate.

[0071] Table 1 shows information for each radiotherapy component. The shortest time can be determined using standard kinematic equations. The information in Table 1 is an example of a kinematic equation considering velocity, distance, and time. In other examples, other factors, including acceleration and inertia, are also considered. Specific equations are determined using kinematic methods that will be understood by those skilled in the art.

[0072] Table 1

[0073]

[0074] The fastest possible time for the radiotherapy device to deliver the arc is the longest of all calculated minimum delivery times. In step 104, the longest delivery time among the minimum delivery times is selected. The component that provides the longest minimum delivery time is selected as the time-limiting component. This is the component of the radiotherapy device that limits the arc delivery time; that is, it is the time-limiting component. This can be the bench, the dose, or any MLC blade. The time-limiting component can vary between segments.

[0075] In step 106, the computer determines whether the time-limited component is an MLC. If the MLC is a time-limited component, the method proceeds to step 107. If the time-limited component is not an MLC, for example, if the gantry or radiation source is a time-limited component, the method proceeds to step 108.

[0076] In step 108, one or more delivery values ​​are set for the time-constrained component. The delivery values ​​are set to default values. Each component may have a defined delivery value (e.g., acceleration and velocity), or it may have a defined individual default value (e.g., an individual dose rate). For clarity, this document uses multiple “delivery values”; however, it should be understood that this is not limiting.

[0077] If the time-limiting component is a radiation source, the dose rate delivery value is set to the default maximum dose rate. If the time-limiting factor is gantry rotation, the delivery value for the gantry is set to the default maximum gantry velocity / acceleration.

[0078] The delivery value of the time-constrained component defines the delivery time for that arc segment. The other two components (i.e., the components without delivery time constraints) must operate at a reduced rate to match the delivery time of the arc segment.

[0079] Once the time-limited component is determined and the delivery value for it is set, the delivery values ​​for the other components are calculated. The expected delivery time corresponds to the delivery time of the time-limited factor. In step 110, the reduced operating rate of the remaining components is calculated to match the expected delivery time of the time-limited component. If the dose is not a time-limited component, the required dose rate can be calculated as: Dose rate = Arc dose / Expected arc time. If the test bench is not a time-limited component, the test bench speed can be calculated as: Expected test bench speed = Test bench travel distance / Expected arc time. If the test bench is not a time-limited component, the test bench speed can be calculated as: Expected blade speed = Blade travel distance / Expected arc time.

[0080] Accordingly, a delivery value is set for each component (time-limited component and each remaining component).

[0081] The calculations described above are simplified calculations considering velocity. Some implementations use the calculations given above. However, it should be understood that in some implementations, acceleration and inertia are also considered. The equations used may differ from those above and can be determined using kinematic methods, as those skilled in the art will understand.

[0082] To account for inertia, we can first model those factors with inertial correlation using a simple and direct linear relationship and the predicted time of the obtained segment. Furthermore, for each segment, we determine the Inertia Compensation Time (ICT) and compare it to this time. Then, in the comparison above, the larger of these is used as the correlation time of that factor over the segment to determine the rate-limiting factor for that segment. If the time chosen for the segment is ICT, this means that all correlation factors will be reduced accordingly. Non-rate-limiting factors will be reduced as before, such that the total time for their segment corresponds to the segment time. The rate-limiting factor's velocity will then also be reduced, such that it completes the segment at a lower velocity than its maximum velocity, allowing for the time during which inertial compensation occurs.

[0083] There are several methods for determining the ICT. Ideally, each geometric term in each instance would be determined by calculating the ICT of a specific instance based on prior knowledge of the dynamics of the particular system. Similar methods can also be used to calculate other examples, such as deceleration and acceleration from non-zero velocity to maximum velocity, and acceleration from non-zero velocity to below maximum velocity.

[0084] Alternatively, the ICT for accelerating a geometric item from rest to its maximum speed can be measured in a specific system and used as the base ICT for accelerating an item from rest to its maximum speed. Other ICT values ​​can then be determined through a direct scaling process. Alternatively, given that all ICTs may be relatively small, a default ICT can be adopted and used for all geometric items of this type in the system. Using the maximum ICT as the default ensures a conservative approach, in which sufficient time is given to compensate for inertia for all geometric items. It is difficult to achieve a lower actual ICT than the default ICT, as the dose rate will be lower than necessary, thus prolonging the treatment time. However, in practice, this effect may be small, thus simplifying the problem by using the default ICT.

[0085] Figure 2 The steps shown in dashed lines illustrate optional additional steps. The delivery value table is output from the delivery planning computer to the control system 20, or to a storage device or user interface. These values ​​are then saved for implementation when the treatment plan is delivered.

[0086] In step 112, the computer outputs a delivery value for each component. These values ​​can be output to a controller, a control computer, or a display device. These values ​​can be output to the radiotherapy apparatus, or to the controller of the radiotherapy apparatus, for controlling or configuring the radiotherapy apparatus based on the delivery values.

[0087] In step 114, the treatment plan is delivered by controlling the components based on the output delivery value.

[0088] Step 106 is performed to determine the optimized delivery values ​​when MLC is the limiting factor. As mentioned above, the default maximum speed and acceleration values ​​selected for MLC are suitable for any situation. These values ​​must take into account the most demanding MLC operating parameters. In most cases, the operating parameters will bear less burden than in the "worst-case" scenario, so the MLC can operate at speeds or accelerations higher than the default maximum values.

[0089] In this method, if the time constraint factor is MLC, the method proceeds to step 107 to set the MLC delivery value. This is as follows: Figure 3 This is done as shown. Once the MLC delivery value has been set, according to... Figure 3 The process continues to step 110. Using the set MLC delivery values, delivery values ​​for the remaining components (stand and radiation source) are calculated to match the expected arc delivery time.

[0090] Figure 3

[0091] Figure 3 A method for optimizing MLC delivery values ​​is illustrated. This method is executed by a delivery planning computer (e.g., delivery planning computer 16) and from... Figure 2 The method begins with step 107.

[0092] Once it is determined that the MLC is the time-constrained component used for delivering arc segments, the operating parameters of the MLC within the delivery plan range are analyzed to determine whether optimization is possible. Computer analysis is used to determine whether the operating parameters meet certain requirements.

[0093] The parameters being evaluated include one or more of the following: thermal load, current load, relative proximity to the blades, number of blades, direction of gravity, driving voltage, and tracking.

[0094] If it is determined that the parameters do not meet the requirements for setting the optimization value, the method proceeds to step 208 and sets the MLC delivery value to the default value.

[0095] If the parameters are determined to meet the requirements and the delivery value of MLC can subsequently be increased within operational constraints, an optimized value can be calculated. The optimized value is calculated in step 202. The optimized value is determined to utilize MLC resources. A lookup table can be used to determine the optimized value. Figure 4 The example shown is how to determine whether the delivery value can be optimized (step 200) and how to determine the optimized value (step 202).

[0096] Once the optimized value has been calculated, in step 204, the optimized value is used to calculate the arc delivery time. If the optimized value is used to operate the arc, this is the time it takes for the MLC to deliver the arc.

[0097] In step 206, the "optimized delivery time" (the time to deliver the arc using the optimized value) is compared with the "default delivery time" (the time to deliver the arc using the default value). If the optimized delivery time meets predefined criteria, for example, if it provides a significant improvement over the delivery time using the default value, the MLC delivery value will be updated to the optimized value.

[0098] In step 206, it is determined whether the difference between the optimized delivery time and the default delivery time meets predefined criteria. Examples of predefined criteria include:

[0099] - Optimized delivery time is less than the default delivery time

[0100] - The optimized delivery time is less than the default delivery time by the amount of time exceeding the pre-defined time: for example, more than 5 seconds.

[0101] - Optimized delivery time is less than the default delivery time by a predetermined percentage, for example, more than 5%.

[0102] Pre-defined criteria are set before the treatment control plan is implemented, and these criteria are stored in the treatment control computer.

[0103] If predetermined criteria are met, it is deemed worthwhile to update the delivery value to the optimized value. Then, in step 210, the computer sets the MLC delivery value to the optimized value. These delivery values ​​are output, and are also output as time-constrained component delivery values. Figure 2 Step 110 of the method. Then, in step 110, the delivery values ​​of the radiation source and gantry rotation are calculated using the optimized delivery time.

[0104] If it is determined in step 206 that the predetermined criteria are not met, the method continues to step 208, and the computer sets the MLC delivery values ​​to default values. These delivery values ​​are output, and are also output as time-constrained component delivery values. Figure 2 Step 110 of the method. Then, in step 110, the delivery values ​​of the radiation source and the gantry rotation are calculated using the default delivery time.

[0105] Figure 4

[0106] Figure 4 A method for evaluating MLC to determine the optimal value is shown. Figure 4 yes Figure 3 A more detailed implementation of the first two steps (steps 200 and 202) of the method. Several parameters of the MLC are taken sequentially. If any parameter meets predetermined requirements, it is determined that the relevant parameter can be "optimized". An optimization value is determined using, for example, a lookup table.

[0107] In step 310, consider the parameters related to MLC. Examples of parameters to be considered are listed below.

[0108] MLC parameters

[0109] 1) Thermal load of the motor, motor drive board / circuit and motor drive power supply.

[0110] 2) Current load of the motor, motor drive board / circuit and motor drive power supply.

[0111] 3) Other motor / gearbox limitations (such as maximum rpm).

[0112] 4) The proximity and relative motion amplitude of the blades.

[0113] 5) The direction of gravity relative to the movement of the blade.

[0114] 6) A simpler proxy for the number of blades in motion (which can be used as 1) and 2).

[0115] 7) Additional field complexity factors (e.g., tumor tracking, the amplitude of tracking motion vectors).

[0116] Each parameter is used to determine whether it meets predetermined requirements that indicate optimization is possible. In some examples, at 320, the parameter is compared to a threshold to determine if optimization is feasible. If the parameter meets the criteria, such as being above or below the threshold, then at 340, an optimized value is set. Sub-selections of the parameters listed above can be considered, such as one or more of the parameters listed above, or all of the parameters listed above. It is not necessary to consider all the criteria for implementing the current method. However, considering fewer criteria at this stage reduces the space available for future optimization.

[0117] Examples of predefined standards for each parameter are shown below. These standards are merely examples, and different standards may be used in other examples.

[0118]

[0119] Once it is determined that the predetermined requirements have been met and optimization is possible, the optimized value is determined. This can be done using, for example, a lookup table stored on a computer. The method proceeds to... Figure 3 Step 204 in the method.

[0120] If the parameters in step 320 do not meet the criteria, the method proceeds to step 330 without setting an optimized delivery value. The method continues to... Figure 3 Step 208.

[0121] Therefore, a method for treatment delivery planning is provided, in which MLC delivery values ​​are optimized if certain conditions are met. This allows for adaptive setting of MLC constraints based on the context of MLC movement within the treatment plan. Consequently, MLC movement can be optimized, thereby reducing treatment plan delivery time.

[0122] A method for determining delivery values ​​for delivering a treatment plan is provided, as well as a computer-readable medium configured to perform the method. A system configured to determine delivery values ​​for delivering a treatment plan is also provided, along with a radiotherapy apparatus including the system.

[0123] The features of the foregoing aspects can be combined in any suitable manner. It should be understood that the above description is by means of specific embodiments of some aspects only, and many modifications and changes will be understood by those skilled in the art and covered by the scope of the appended claims.

Claims

1. A method for calculating a delivery value, the delivery value being used to deliver an arc segment between two control points in a treatment plan, the treatment plan specifying an MLC leaf position at each control point, the method comprising: The default delivery value is used to calculate the arc delivery time for each of the multiple components, one of which is the MLC blade motion. Select the component indicating the delivery time of the longest arc segment as the time limit component; as well as If the time-limiting component is MLC blade motion: Provides optimized MLC delivery values; If the predetermined conditions are met, the time-limited component delivery value is set to the optimized MLC delivery value; and Output the time-limited component delivery value.

2. The method according to claim 1, further comprising: The optimized arc delivery time is calculated using the optimized MLC delivery value; as well as The optimized arc segment delivery time is compared with the longest arc segment delivery time to determine whether the predetermined condition is met.

3. The method according to claim 2, further comprising: If the optimized arc segment delivery time is longer than the longest arc segment delivery time, then the time limit component delivery value is set to the default delivery value; as well as If the optimized arc segment delivery time is shorter than the longest arc segment delivery time, then the time-limited component delivery value is set to the optimized MLC delivery value.

4. The method according to any one of claims 1 to 3, wherein, The optimized MLC delivery values ​​provided include: Select the MLC parameters for delivery of the arc segment; Determine whether the MLC parameters meet the predetermined requirements; and If the predetermined requirements are met, the optimized MLC delivery value is determined.

5. The method according to claim 4, wherein, Determining the optimized MLC delivery value involves selecting the optimized MLC delivery value from a lookup table.

6. The method according to claim 4, wherein, The MLC parameters include one or more of the following: thermal load, current load, maximum rpm, motor / gearbox constraints, relative blade proximity and relative motion amplitude, gravity direction relative to blade motion, number of moving blades, tumor tracking requirements, and amplitude of the tracking motion vector.

7. The method according to any one of claims 1 to 3, wherein, The treatment plan also includes the bench location at each control point and the dosage for each arc segment.

8. The method according to any one of claims 1 to 3, wherein: If the time-constrained component is not an MLC, the method further includes: Set the time-limited component delivery value to the corresponding default delivery value.

9. The method according to any one of claims 1 to 3, wherein, Once the time-limited component delivery value has been set, the method further includes: For each remaining component, a reduced delivery value is calculated to match the arc delivery time of the time-constrained component.

10. The method according to any one of claims 1 to 3, wherein, The default delivery value includes at least one of the following: maximum blade velocity; maximum blade acceleration; Maximum table rotation speed; Maximum rotational acceleration of the test bench; and maximum dose rate.

11. The method according to any one of claims 1 to 3, further comprising: Repeat the above method for each of the multiple arcs in the treatment plan.

12. The method according to any one of claims 1 to 3, further comprising: The determined delivery value is output to a controller, which controls the radiotherapy equipment to deliver the treatment plan according to the output delivery value.

13. The method of claim 12, further comprising: The radiotherapy device is controlled to operate the components at their respective delivery values.

14. The method of claim 13, comprising: The first arc segment and the second arc segment are delivered, wherein the radiation between the first arc segment and the second arc segment is uninterrupted.

15. The method according to any one of claims 1 to 3, wherein, A set of optimized MLC delivery values ​​is provided, including: For each of the multiple MLC parameters, determine whether the MLC parameter is below a threshold; If all delivery parameters are below the corresponding thresholds, the optimized MLC delivery value from the lookup table is output.

16. A computer-readable medium comprising computer-executable instructions configured to perform the method as claimed in any one of claims 1 to 15.

17. A radiotherapy apparatus comprising a source capable of emitting a therapeutic radiation beam along a beam axis, and a multi-leaf collimator arranged to collimate the beam into a desired shape, wherein the source is rotatable about an axis of rotation substantially orthogonal to and intersecting the beam axis, thereby describing an arc along that axis. It also includes a planning computer, which includes computer-readable instructions configured to perform the method of any one of claims 1 to 15 when executed by the planning computer.

18. The radiotherapy apparatus of claim 17, further comprising a controller configured to control the radiotherapy apparatus to deliver a treatment plan based on output delivery values ​​from the planning computer.

Images