Spatial Fractionation Radiotherapy Methods and Devices

Abstract

To facilitate the application of non-uniform radiation dose to the patient's target volume using spatially segmented radiotherapy, control circuit (101) accesses (201) a three-dimensional representation of the patient's target volume, superimposes (202) a mesh including lattice radiotherapy vertices onto the three-dimensional representation of the patient's target volume to provide a first obtained patient target volume representation, removes (203) at least some lattice radiotherapy vertices located outside the first obtained patient target volume representation to provide a second obtained patient target volume representation, and moves (204) at least some lattice radiotherapy vertices located inside the second obtained patient target volume representation (e.g., by moving lattice radiotherapy vertices to nodes of the centroid Voronoi mosaic) to provide a third obtained patient target volume representation.

Description

Technical Field

[0001] This disclosure relates to a method for adjusting a patient's target volume representation for use in a treatment plan to administer a non-uniform radiation dose to the patient's target volume using spatially fractionated radiotherapy, and to an apparatus for administering a non-uniform radiation dose to the patient's target volume using spatially fractionated radiotherapy. These teachings generally relate to facilitating the use of energy to treat a patient's planned target volume according to an energy-based treatment plan, and more specifically to optimizing energy-based treatment plans. Background Technology

[0002] The use of energy to treat medical conditions encompasses well-known existing technological fields. For example, radiation therapy is a crucial component of many treatment programs aimed at reducing or eliminating unwanted tumors. Unfortunately, the energy applied is inherently indiscriminate between unwanted substances and adjacent tissues, organs, etc., that are desired or even vital for the patient's continued survival. As a result, energy, such as radiation, is typically applied in a carefully controlled manner to at least attempt to confine the energy to a given target volume. So-called radiation therapy programs generally function in this regard.

[0003] Radiation therapy plans typically consist of specified values ​​for each of a variety of treatment platform parameters for each period in multiple consecutive fields. Treatment plans for radiation therapy sessions are usually generated automatically through a process known as optimization. As used herein, "optimization" will be understood as referring to improving candidate treatment plans without necessarily ensuring that the optimized result is in fact the only optimal solution. Such optimization typically involves automatically adjusting one or more physical therapy parameters (usually while simultaneously adhering to one or more corresponding constraints in these respects) and mathematically calculating possible corresponding treatment outcomes (such as dose levels) to identify a given set of treatment parameters that represents a good trade-off between the desired treatment outcome and the avoidance of undesirable collateral effects.

[0004] Developing radiation therapy plans can sometimes be heavily reliant on clinician input and / or supervision. Spatial fractionation radiation therapies, such as lattice radiotherapy, can be particularly demanding in these respects. Summary of the Invention

[0005] In one aspect, the invention provides a method, as defined in claim 1, for adjusting a patient's target volume representation for use in treatment planning to facilitate the application of a non-uniform radiation dose to the patient's target volume using spatially fractionated radiotherapy. Optional features are specified in the dependent claims.

[0006] In another aspect, the present invention provides an apparatus, as defined in claim 11, for facilitating the application of a non-uniform radiation dose to a patient's target volume using spatially fractionated radiotherapy. Optional features are specified in the dependent claims.

[0007] The present invention also provides a method for administering a non-uniform radiation dose to a patient's target volume using spatially fractionated radiotherapy, the method comprising the following steps: Control circuit: Access a three-dimensional representation of the patient's target volume; The mesh including the vertices of the lattice radiotherapy is overlaid with a three-dimensional representation of the patient's target volume to provide a first-order target volume representation of the patient; Remove at least some lattice radiotherapy vertices located outside the target volume representation of the first obtained patient to provide a target volume representation of the second obtained patient; At least some lattice radiotherapy vertices located inside the target volume representation of the second obtained patient are moved in the lattice radiotherapy vertices to provide a target volume representation of the third obtained patient. Attached Figure Description

[0008] The above-mentioned needs are at least partially met by providing the spatially segmented radiotherapy method and apparatus described in the following specific embodiments, particularly when studied in conjunction with the accompanying drawings, in which:

[0009] Figure 1 Including block diagrams configured according to various embodiments of these teachings;

[0010] Figure 2 Includes flowcharts of various embodiments configured according to these teachings;

[0011] Figure 3 Includes schematic representations of various embodiments configured in accordance with these teachings;

[0012] Figure 4 Includes schematic representations of various embodiments configured in accordance with these teachings;

[0013] Figure 5 Includes schematic representations of various embodiments configured in accordance with these teachings;

[0014] Figure 6 Includes schematic representations of various embodiments configured in accordance with these teachings;

[0015] Figure 7 Including schematic representations of configurations according to various embodiments of the present invention;

[0016] Figure 8Includes schematic representations of various embodiments configured in accordance with these teachings;

[0017] Figure 9 Including flowcharts of configurations according to various embodiments of the present invention;

[0018] Figure 10 Including schematic representations of various embodiments configured according to these teachings; and

[0019] Figure 11 This includes schematic representations of various embodiments configured in accordance with these teachings.

[0020] The elements in the accompanying drawings are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the size and / or relative position of some elements in the drawings may be exaggerated relative to other elements to aid in understanding the various embodiments of this disclosure. Furthermore, common but easily understood elements that are useful or necessary in practically feasible embodiments are generally not depicted to provide a less obstructed view of these various embodiments of the teachings. Certain actions and / or steps may be described or depicted in a particular sequence of occurrence, and those skilled in the art will understand that such specificity regarding the sequence is not actually necessary. Unless otherwise set forth herein with different specific meanings, the terms and expressions used herein have the ordinary technical meaning as those skilled in the art would assign to them. Unless expressly indicated otherwise, the word “or” as used herein should be interpreted as having a disjunctive construction rather than a conjunctive construction. Detailed Implementation

[0021] In general, these teachings facilitate the application of non-uniform radiation doses to a patient's target volume using spatially segmented radiotherapy. These teachings include: accessing a three-dimensional representation of the patient's target volume; superimposing a mesh including lattice radiotherapy vertices onto the three-dimensional representation of the patient's target volume to provide a first obtained target volume representation of the patient; removing at least some lattice radiotherapy vertices located outside the first obtained target volume representation of the patient's target volume to provide a second obtained target volume representation of the patient's target volume; and moving at least some lattice radiotherapy vertices located inside the second obtained target volume representation of the patient's target volume to provide a third obtained target volume representation of the patient's target volume.

[0022] Accessing the aforementioned three-dimensional representation of the patient's target volume through a method includes: accessing a three-dimensional mesh representation.

[0023] By means of a method, the aforementioned mesh including lattice radiotherapy vertices comprises at least one of a three-dimensional cubic mesh and / or a three-dimensional hexagonal mesh. The aforementioned superposition of the mesh with a three-dimensional representation of the patient's target volume may include: by means of a method co-locating at least some of the lattice radiotherapy vertices with nodes of the mesh.

[0024] Removing at least some lattice radiotherapy vertices located outside the target volume representation of the first obtained patient by a method may include: removing all lattice radiotherapy vertices located outside the target volume representation of the first obtained patient.

[0025] One method for moving at least some lattice radiotherapy vertices located inside the target volume representation of a second-obtained patient may include: moving the lattice radiotherapy vertices to nodes of a centroidal Voronoi tessellation. These teachings will be adapted to generate such a centroidal Voronoi tessellation according to the Lloyd algorithm and / or, if necessary, according to minimizing the objective function.

[0026] These teachings are highly flexible in practice and will be adapted, for example, to optimize lattice radiotherapy treatment plans based on the target volume representation of the patient obtained in the third step above, to provide optimized radiation therapy plans, and then, if desired, to administer radiation therapy to the patient according to the optimized radiation therapy plans.

[0027] The lattice vertices configured in this way can be automatically and uniformly spaced and are three-dimensionally conformal, with all relevant planning features located within the patient treatment volume.

[0028] These and other benefits become clearer after a thorough reading and study of the following specific embodiments. Reference is now made to the accompanying drawings, and specifically to... Figure 1 First, an exemplary device 100 compatible with many of the teachings in these teachings will be presented.

[0029] In this particular example, the enabling device 100 includes a control circuit 101. As a “circuit”, the control circuit 101 therefore includes a structure having at least one (and typically many) conductive paths (such as paths including conductive metals such as copper or silver), at least one conductive path transmitting power in an orderly manner, and the path(s) will typically also include corresponding electrical components (both passive components (such as resistors and capacitors) and active components (such as any of a variety of semiconductor-based devices) as needed) to allow the circuit to implement the control aspects of these teachings.

[0030] Such control circuitry 101 may include a fixed-purpose hardwired hardware platform (including, but not limited to, application-specific integrated circuits (ASICs) (which are integrated circuits customized for a specific purpose rather than intended for general use), field-programmable gate arrays (FPGAs), etc.), or may include a partially or fully programmable hardware platform (including, but not limited to, microcontrollers, microprocessors, etc.). These architectural choices for such a structure are well-known and understood in the art and need not be described further herein. The control circuitry 101 is configured (e.g., by means of appropriate programming, as will be well understood by those skilled in the art) to perform one or more of the steps, actions, and / or functions described herein.

[0031] Control circuitry 101 is operatively coupled to memory 102. Depending on the requirements, memory 102 may be integrated with control circuitry 101 or may be physically separate (whole or part) from control circuitry 101. Memory 102 may also be local to control circuitry 101 (e.g., both sharing a common circuit board, chassis, power supply, and / or enclosure), or may be partially or completely remote from control circuitry 101 (e.g., memory 102 is physically located in another facility, metropolitan area, or even region compared to control circuitry 101).

[0032] In addition to information such as optimization information for specific patients and information about specific radiation therapy platforms as described herein, the memory 102 can, for example, be used to non-transitory store computer instructions that, when executed by the control circuitry 101, cause the control circuitry 101 to operate as described herein. (As used herein, the reference to "non-transitory" shall be understood to refer to a non-transient state of the stored content (and thus excludes the case where the stored content constitutes only a signal or wave), rather than to the volatility of the storage medium itself, and therefore includes both non-volatile memory (such as read-only memory (ROM)) and volatile memory (such as dynamic random access memory (DRAM)).

[0033] Alternatively, the control circuitry 101 may also be operatively coupled to the user interface 103. The user interface 103 may include various user input mechanisms (such as, but not limited to, keyboards and keypads, cursor control devices, touch-sensitive displays, voice recognition interfaces, gesture recognition interfaces, etc.) and / or user output mechanisms (such as, but not limited to, visual displays, audio transducers, printers, etc.) to facilitate receiving information and / or instructions from the user and / or providing information to the user.

[0034] If needed, the control circuitry 101 can also be operatively coupled to a network interface (not shown). The control circuitry 101 configured in this way can communicate with other components (both internal and external to the device 100) via the network interface. Network interfaces, including both wireless and non-wireless platforms, are well understood in the art and do not require special description here.

[0035] By means of a method, such as computed tomography device 106 and / or other imaging device 107 as known in the art, some or all of any desired patient-related imaging information can be sourced.

[0036] In this exemplary example, control circuitry 101 is configured to ultimately output an optimized energy-based treatment plan (such as, for example, an optimized radiation therapy plan 113). This energy-based treatment plan typically includes specified values ​​for each of a variety of treatment platform parameters during each of a plurality of consecutive exposure fields. In this case, the energy-based treatment plan is generated through an optimization process, an example of which is provided separately herein.

[0037] In one method, control circuitry 101 is operatively coupled to an energy-based treatment platform 114, which is configured to direct treatment to a patient having at least one treatment volume 105 and one or more organs at risk (in an energy-based treatment plan 113) according to an optimized energy-based treatment plan 113. Figure 1 Therapeutic energy 112 is delivered to the corresponding patient 104 (represented by the first organ at risk 108 to the Nth organ at risk 109). These teachings are generally applicable to any of a wide range of energy-based therapeutic platforms / devices. In a typical application setting, the energy-based therapeutic platform 114 will include an energy source such as a radiation source 115, such as ionizing radiation 116.

[0038] In one method, the radiation source 115 can be selectively moved along an arc-shaped path via a gantry (the path at least partially surrounds the patient during treatment). If desired, the arc-shaped path can comprise a complete or near-complete circle. In another method, control circuitry 101 controls the movement of the radiation source 115 along the arc-shaped path, and can accordingly control when the radiation source 115 begins to move, stops moving, accelerates, decelerates, and / or the speed at which the radiation source 115 travels along the arc-shaped path.

[0039] As an illustrative example, radiation source 115 may include, for example, an X-ray source based on a radio frequency (RF) linear particle accelerator (a linac-based accelerator). A linac is a type of particle accelerator that greatly increases the kinetic energy of charged subatomic particles or ions by subjecting charged particles to a series of oscillating potentials along a linear beamline. This can be used to generate ionizing radiation (e.g., X-rays) 116 and high-energy electrons.

[0040] A typical energy-based treatment platform 114 may also include one or more support devices 110 (such as a bed) for supporting the patient 104 during treatment, one or more patient fixation devices 111, a gantry or other movable mechanism for allowing selective movement of the radiation source 115, and one or more energy shaping devices (e.g., bundle shaping devices 117 such as a narrow-aperture multi-leaf collimator, etc.) for providing selective energy shaping and / or energy modulation as needed.

[0041] In a typical application setting, it is assumed herein that the patient support device 110 can be selectively controlled by control circuitry 101 to move in any direction (i.e., any X, Y, or Z direction) during energy-based treatment sessions. Since the aforementioned components and systems are well understood in the art, further elaboration of these aspects is not provided herein unless otherwise relevant to the description.

[0042] Now for reference Figure 2 The following describes a process 200 that can be performed, for example, in conjunction with the application settings described above (and more specifically via the control circuit 101 described above). In general, this process 200 can be used to facilitate the generation of an optimized radiation therapy plan 113, thereby facilitating the treatment of a specific patient using therapeutic radiation on a specific radiation therapy platform according to the optimized radiation therapy plan. The application of therapeutic radiation is an optional feature of the method and can be omitted.

[0043] For illustrative purposes, the following description assumes that radiation therapy includes spatially fractionated radiation therapy. More specifically, lattice radiation therapy. Lattice radiation therapy is a type of spatially fractionated radiation therapy that facilitates the delivery of highly non-uniform doses to relatively large tumors. Lattice radiation therapy originates from the use of a conventional two-dimensional grid (where groups of parallel beams pass through the target volume) to create peak and trough doses in three dimensions by using multi-directional beams. In lattice radiation therapy, the radiation beams are delivered from different directions. Therefore, lattice radiation therapy facilitates the creation of three-dimensional arrays or matrices in which high-dose and low-dose zones alternate in all spatial directions.

[0044] At box 201, the process 200 provides access to a three-dimensional representation of the patient's target volume (such as a relatively large tumor). One method allows the three-dimensional representation of the patient's target volume to include a three-dimensional raster representation. Figure 3 This section presents a simplified illustrative example of a 3D raster representation 301 where the target volume is a simple sphere. A 3D raster representation is a digital model describing the surface geometry of a 3D object. Such a representation comprises a set of vertices, edges, and faces that define the shape and structure of the object. In a raster representation, each vertex represents a point in 3D space, and edges connect these vertices to form the boundaries of the object's surface. Faces (typically triangles or quadrilaterals) are formed by connecting three or four vertices together. These faces cover the surface of the object, in this case, a representation of the patient's target volume.

[0045] At box 202, and in accordance with lattice radiotherapy practice, control circuitry 101 superimposes a mesh including the lattice radiotherapy vertices onto a three-dimensional representation of the patient's target volume to provide a first obtained representation of the patient's target volume. (Temporary reference) Figure 4 and Figure 5 Lattice radiotherapy treatment plans typically involve creating small spheres called vertices within the tumor volume, to which high doses are delivered. These vertices (some of which are indicated by reference numeral 401) are usually placed in a regular three-dimensional array / grid (such as... Figure 4 The three-dimensional cubic mesh shown is 400 or Figure 5 On the nodes of the three-dimensional hexagonal mesh (500) shown.

[0046] Accordingly, and refer to Figure 2 and Figure 6 Both, at box 202, control circuit 101 superimposes a mesh 601 including lattice radiotherapy vertices with a three-dimensional mesh representation 301 of the patient's target volume by, for example, co-locating at least some of the lattice radiotherapy vertices with nodes of the mesh. Unfortunately, several problems can arise when vertices are positioned on such a regular mesh. As an example, areas located at the edges of the target volume may be underexposed, leading to uncertain clinical outcomes. As another example, lattice radiotherapy is often used in application settings dealing with very large, bulky tumors. In such cases, it is not uncommon for organs at risk to overlap with the planned target volume. With the current vertex positioning, one or more vertices may be placed in areas overlapping with organs at risk. This teaching can address the aforementioned problems as described below.

[0047] Continue to refer to Figure 2 And also refer to Figure 7At block 203, control circuitry 101 removes at least some lattice radiotherapy vertices located outside the target volume representation of the first obtained patient to provide a target volume representation 700 for the second obtained patient. Alternatively, the target volume representation 700 for the second patient may include removing all lattice radiotherapy vertices located outside the target volume representation of the first obtained patient.

[0048] At box 204, and now also referencing Figure 8 The control circuit 101 moves at least some of the lattice radiotherapy vertices located within the target volume representation 700 of the second obtained patient to provide a target volume representation 800 for the third obtained patient. If properly performed, such movement can help avoid underexposure of the patient's target volume and can also help ensure sparing of organs at risk.

[0049] These teachings will be adapted to various methods of moving lattice radiotherapy vertices. Figure 9 One approach is presented in these aspects.

[0050] At box 901, control circuit 101 generates a centroid Voronoi tessellation. In general, a centroid Voronoi tessellation is a technique for dividing a given space into regions called Voronoi units based on a set of points called the centroid. (A "tessellation" is a geometric concept involving covering a surface with a repeating pattern of shapes (called tiles or polygons) without any gaps or overlaps. These tiles can be regular or irregular in shape.)

[0051] These teachings will be adapted to various ways of generating the centroid Voronoi mosaic. For example, control circuit 101 can generate the centroid Voronoi mosaic based on minimizing the objective function.

[0052] As another example, control circuit 101 can generate a centroid Voronoi tessellation based on Lloyd's algorithm. Lloyd's algorithm (also known as Voronoi iteration or relaxation) is an algorithm used to find uniformly spaced sets of points in subsets of Euclidean space and partition these subsets into well-shaped and uniformly sized convex cells. In general, the above may include: determining the intersection points of Voronoi cells and grid volumes, moving vertices towards the centroid (center of mass) of the Voronoi cells, and repeating the above operations until the vertices no longer move and convergence is achieved. Figure 10A simple illustrative example of these aspects is provided through a series of iterations 1000, where the current site position is shown as a solid circle, and where a hollow circle represents the centroid of the Voronoi element. The fourth iteration 1001 in this simple example depicts the aforementioned convergence state.

[0053] Lloyd's algorithm may converge slowly. To overcome this potential limitation, the generation of centroid Voronoi mosaics can be formulated as a minimization problem. The goal is to minimize the following objective function: Objective function: (1) gradient: (2)

[0054] The above content represents the expression of the objective function and gradient used to generate the centroid Voronoi mosaic. In these equations, It is the intersection of the i-th Voronoi cell and the mesh volume. and These are the position of the i-th vertex and its Voronoi unit. The moment of inertia. and They are Quality and Quality Center.

[0055] For reference only Figure 11 In order to enforce that vertices are placed only in areas where there is no overlap between the target volume of the patient and the organs at risk, these teachings will be adapted to automatically select the difference 1101 between the patient's treatment volume grid 1102 and the organs at risk grid 1103 to generate a centroid Voronoi mosaic.

[0056] Refer again Figure 9 At box 902, control circuit 101 can then move at least some or all of the lattice radiotherapy vertices located inside the target volume representation of the second obtained patient by moving the lattice radiotherapy vertices to nodes of the centroid Voronoi mosaic.

[0057] Refer again Figure 2 At option 205, the process 200 can then provide an optimized lattice radiotherapy treatment plan based on the third obtained patient target volume representation 800 to provide an optimized radiation therapy plan 113. At option 206, the process 200 will then adapt the radiation therapy (e.g., lattice radiotherapy) administered to the patient 104 according to the optimized radiation therapy plan 113.

[0058] It should be understood that the use of centroid Voronoi mosaic helps ensure that the lattice vertices are both uniformly spaced and three-dimensionally conformal. In one approach, the only input required to achieve vertex placement according to these teachings is the distance between the two spots (highly relevant to clinical outcomes) and a three-dimensional representation of the patient's structure (which is typically calculated in many treatment planning systems). Once the clinician has selected the spacing, the three-dimensional localization can then be fully automated without requiring any additional input from the clinician.

[0059] This disclosure also ensures that all spheres are within the patient's treatment volume, and therefore the results do not need to be reviewed individually by clinicians (representing the methods of prior art practice).

[0060] It should also be understood that these teachings can produce standard ways of creating plans, thereby enabling fair comparisons between, for example, two lattice plans that may be created using two different specified spacings.

[0061] Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made to the above embodiments without departing from the scope of the invention, and such modifications, alterations, and combinations will be considered to be within the scope of the concept of the invention.

Claims

1. A method for adjusting a patient's target volume representation, the method being used in treatment planning to facilitate the application of a non-uniform radiation dose to the patient's target volume using spatially fractionated radiotherapy, the method comprising the steps of: Control circuit: Access a three-dimensional representation of the target volume of the patient; The mesh including the vertices of the lattice radiotherapy is superimposed on the three-dimensional representation of the target volume of the patient to provide a first obtained target volume representation of the patient; Remove at least some of the lattice radiotherapy vertices located outside the target volume representation of the first obtained patient to provide a target volume representation of the second obtained patient; Move at least some of the lattice radiotherapy vertices located inside the target volume representation of the second obtained patient to provide a target volume representation of the third obtained patient.

2. The method of claim 1, wherein accessing the three-dimensional representation of the target volume of the patient comprises: Access the 3D raster representation.

3. The method of claim 1 or 2, wherein the grid of the lattice radiotherapy vertex comprises at least one of the following: 3D cubic mesh; and Three-dimensional hexagonal mesh.

4. The method according to claim 1, 2, or 3, wherein removing at least some of the lattice radiotherapy vertices located outside the target volume represented by the first obtained patient comprises: Remove all lattice radiotherapy vertices located outside the target volume representation of the first obtained patient from the lattice radiotherapy vertices.

5. The method according to any one of claims 1 to 4, wherein superimposing the mesh including the lattice radiotherapy vertex with the three-dimensional representation of the target volume of the patient comprises: At least some of the lattice radiotherapy vertices are co-located with the nodes of the mesh.

6. The method according to any one of claims 1 to 5, wherein moving at least some of the lattice radiotherapy vertices located inside the target volume representation of the second obtained patient comprises: Move the lattice radiotherapy vertex to a node in the centroid Voronoi mosaic.

7. The method according to claim 6, further comprising: The centroid Voronoi mosaic is generated according to Lloyd's algorithm.

8. The method according to claim 6, further comprising: The centroid Voronoi mosaic is generated by minimizing the objective function.

9. The method according to any one of claims 1 to 8, further comprising: Based on the target volume representation of the third patient, the lattice radiotherapy treatment plan is optimized to provide an optimized radiation therapy plan.

10. The method of claim 9, further comprising: Radiation therapy was administered to the patient according to the optimized radiation therapy plan.

11. An apparatus for facilitating the application of a non-uniform radiation dose to a patient's target volume using spatially fractionated radiotherapy, the apparatus comprising: Control circuit, the control circuit being configured to: Access a three-dimensional representation of the target volume of the patient; The mesh including the vertices of the lattice radiotherapy is superimposed on the three-dimensional representation of the target volume of the patient to provide a first obtained target volume representation of the patient; Remove at least some of the lattice radiotherapy vertices located outside the target volume representation of the first obtained patient to provide a target volume representation of the second obtained patient; and Move at least some of the lattice radiotherapy vertices located inside the target volume representation of the second obtained patient to provide a target volume representation of the third obtained patient.

12. The apparatus of claim 11, wherein the control circuitry is configured to access the three-dimensional representation of the target volume of the patient by accessing a three-dimensional grid representation.

13. The apparatus of claim 11 or 12, wherein the grid of the lattice radiotherapy vertex comprises at least one of the following: 3D cubic mesh; and Three-dimensional hexagonal mesh.

14. The apparatus of claim 11, 12 or 13, wherein the control circuit is configured to: remove at least some of the lattice radiotherapy vertices located outside the target volume of the first obtained patient by removing all of the lattice radiotherapy vertices located outside the target volume of the first obtained patient.

15. The apparatus of any one of claims 11 to 14, wherein the control circuitry is configured to superimpose the mesh comprising the lattice radiotherapy vertices with the three-dimensional representation of the target volume of the patient by co-locating at least some of the lattice radiotherapy vertices with nodes of the mesh.

16. The apparatus according to any one of claims 11 to 15, wherein the control circuit is configured to move at least some of the lattice radiotherapy vertices located inside the target volume representation of the second obtained patient by moving the lattice radiotherapy vertices to nodes of the centroid Voronoi mosaic.

17. The apparatus of claim 16, wherein the control circuit is further configured to: The centroid Voronoi mosaic is generated according to Lloyd's algorithm.

18. The apparatus of claim 16, wherein the control circuit is further configured to: The centroid Voronoi mosaic is generated by minimizing the objective function.

19. The apparatus according to any one of claims 11 to 18, wherein the control circuit is further configured to: The lattice radiotherapy treatment plan is optimized based on the target volume representation of the third patient to provide an optimized radiation therapy plan.

20. The apparatus of claim 19, wherein the control circuit is further configured to: Radiation therapy was administered to the patient according to the optimized radiation therapy plan.

Images