CN110876839B - Dose calculation method for non-uniform grid distribution simulation linear accelerator treatment plan - Google Patents
Dose calculation method for non-uniform grid distribution simulation linear accelerator treatment plan Download PDFInfo
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- A61N5/1042—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy with spatial modulation of the radiation beam within the treatment head
- A61N5/1045—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy with spatial modulation of the radiation beam within the treatment head using a multi-leaf collimator, e.g. for intensity modulated radiation therapy or IMRT
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- A61N5/1071—Monitoring, verifying, controlling systems and methods for verifying the dose delivered by the treatment plan
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- A61N5/103—Treatment planning systems
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Abstract
The invention belongs to the field of radiotherapy dose calculation, and relates to a method, equipment and a storage medium for calculating treatment plan dose of a non-uniform grid distribution simulation linear accelerator. The method comprises the following steps: setting non-uniform grid parameters and initial flux values of corresponding grids; calculating to obtain the contribution of each grid to the total dose distribution, and obtaining the dose of the whole radiation field in the selected die body after superposition; comparing the difference between the actual dose and the dose calculation; if the difference is within the preset calculation precision range, receiving the current grid segmentation parameters and flux values for dose calculation of the patient treatment plan; and if the difference exceeds the preset calculation precision range, finely adjusting the separation of the grids in the y direction and the flux value corresponding to each grid, and then calculating the dose until the calculation result meets the preset precision. According to the invention, the radiation dose is calculated through the non-uniform two-dimensional flux grid without adjusting the resolution of the grid, and the dose value of each grid can be directly calculated according to mechanical parameters, so that the number of the grids is controllable.
Description
Technical Field
The invention belongs to the field of radiotherapy dose calculation, and relates to a treatment plan dose calculation method, equipment and a storage medium of a non-uniform grid distribution simulation linear accelerator.
Background
In the existing method for treating cancer by using a linear accelerator, a treatment plan is generally made for a tumor region of each patient by using the TPS, and the quality of the plan is influenced by various factors, such as the level of planning made by a physicist, the performance of a TPS optimization algorithm, whether dose calculation can be accurately simulated, and the like. The dose calculation precision directly influences the iteration direction of the optimization algorithm and the judgment of a physicist, and becomes a basic index for measuring the quality of the TPS.
Since the purpose of dose calculation is to simulate the deposition distribution of the linac treatment head beam on the real patient dose to provide a basis for prediction of actual radiotherapy, improving the accuracy of dose calculation has been the direction of effort in the field of radiotherapy. With the increasing precision of processing and motion control, the radiation therapy really advances towards the precise therapy. Due to accurate control, high dose rate is implemented, and irradiation time is shortened, so that the method for effectively killing the tumor and reducing the dose received by normal tissues is more and more accepted by people. The accuracy of the dose calculation method must be improved in this process.
The dose calculation method models the therapy head separately from the outgoing beam portion of the patient and the beam limiting portion required for treatment for each patient. Verification of dose calculation when simulating the accuracy of the treatment head independent of the outgoing beam part of the patient, a very high accuracy can be achieved through parameter adjustment due to the fixed components, assuming that the outgoing beam of the accelerating tube is stable. However, when each patient is simulated to be treated, because the shapes of the tungsten gate and the multi-leaf collimator (MLC) are not fixed, different superpositions of different shapes in the same direction are also needed to meet the expected treatment requirements, and how to describe the scattering and projection of the beam on the complex shapes is always a difficult point of improving the dose calculation method. The existing method is to project the radiation field formed by two beam limiting devices to an isocenter plane and divide the radiation field into two-dimensional grids at equal intervals. The beam flux is adjusted by the corresponding occlusion area at each grid device. The method simulates the influence of two beam limiting devices on a treatment beam to a certain extent, but if the resolution of the grid is too large, other correction methods are required to be added to simulate the leaf protrusion and the grooving; if the resolution of the grid is too small, increasing the number of calculations results in too long a dose calculation time to affect clinical use.
Disclosure of Invention
In order to solve the problems of low precision, long calculation time and the like in beam flux formed by the equally-spaced two-dimensional grid calculation simulation tungsten gate and the multi-leaf collimator, the technical scheme provides a method, equipment and a storage medium for calculating treatment plan dose of a non-uniform grid distribution simulation linear accelerator.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention uses non-uniform two-dimensional grid, using input parameters (including parameters of machine motion, size of tungsten gate of the machine; thickness, protrusion, notch and motion parameters of each multi-leaf collimator leaf) as non-uniform grid spacing parameters. The specific method comprises the following steps: the boundaries of the grid are defined, in terms of minimum positions of two pairs of tungsten gates. The first segmentation in the y-direction of the two-dimensional flux grid (i.e., the thickness direction of the multi-leaf collimator) is set according to the thickness of the leaves of the multi-leaf collimator, while the second segmentation in the y-direction is performed according to the coupling between leaves of the multi-leaf collimator (typically the length of the protrusions and notches in the leaves). If the error between the dose calculation and the actual measurement exceeds the preset range, the result of the secondary segmentation can be further finely adjusted, and the adjusted length is called as the equivalent length. The x-direction (direction of motion of the multi-leaf collimator) gridding of the two-dimensional flux grid can be of equal spacing (less than the value of the separation of a pair of leaves when closed) or unequal spacing. During dose calculation, the measured leakage rate is combined to define the flux value of the corresponding grid in which the inter-chip leakage occurs in a real plan, and the rest adjusts the beam flux according to the shielding area.
A non-uniform grid distribution simulated linac treatment plan dose calculation method, adapted to be executed in a computing device, comprising the steps of:
(1) setting non-uniform grid parameters:
(i) setting the boundaries of a two-dimensional flux grid for dose calculation;
(ii) preliminarily dividing an initial grid spacing of the two-dimensional flux grid in the y direction (perpendicular to the motion direction of the multi-leaf collimator) according to the thickness of the leaves of the multi-leaf collimator;
(iii) the grid spacing of the two-dimensional flux grid in the y direction is divided again according to the coupling position between the multi-leaf collimator pieces to obtain a quadratic division grid spacing in the y direction;
(iv) setting the grid spacing in the x-direction (direction of motion of the multi-leaf collimator) of the two-dimensional flux grid;
(2) setting an initial flux value of a corresponding grid according to an inter-chip leakage transmission measurement result;
(3) calling a dose calculation method to calculate according to the non-uniform grid parameters and the initial flux values corresponding to the grids to obtain the contribution of each grid to the total dose distribution, and finally overlapping the dose calculation results of the grids to obtain the dose distribution of the whole radiation field in the selected die body;
(4) measuring the true dose of the selected die body under the radiation field;
(5) comparing the integral difference between the actual dose and the dose calculation, and judging whether the difference between the actual dose and the dose calculation is within a preset calculation precision range;
if the difference is within the preset calculation precision range, receiving the current grid segmentation parameters and flux values for dose calculation of a subsequent patient treatment plan;
if the difference exceeds the preset calculation precision range, repeating the steps (6) - (7); until the difference between the dose calculation result and the real dose meets the preset precision;
(6) further adjusting the grid spacing of the two-dimensional flux grid in the y direction to obtain the optimized grid spacing in the y direction; and/or further adjusting the initial flux value corresponding to each grid to obtain an optimized flux value;
(7) and according to the optimized grid parameters and the optimized flux values corresponding to the grids, calling a dose calculation method to calculate and obtain the contribution of each grid to the total dose distribution, and finally overlapping the dose calculation results of the grids to obtain the dose of the whole portal in the selected phantom.
In step (i), the boundaries of the two-dimensional flux grid for dose calculation are determined by the maximum outer contour formed by the tungsten gate motion in each treatment plan. In step (ii), the grid spacing in the y-direction (perpendicular to the moving direction of the multi-leaf collimator) of the preliminarily segmented two-dimensional flux grid is consistent with the thickness of the leaf of the multi-leaf collimator corresponding to the grid spacing.
In step (iii), the grid spacing in the y-direction of the two-dimensional flux grid is again segmented according to the position of the protrusions (tongue) and/or notches (grooves) in the multi-leaf collimator.
In the step (iv), the grid in the x direction of the two-dimensional flux grid is divided into equal-interval division;
in step (iv), the spacing between adjacent grids in the x-direction of the two-dimensional flux grid is less than the value of the spacing when a pair of vanes are closed.
In the step (3), the dose calculation method is a Monte Carlo dose calculation method (Monte Carlo), a Pencil Beam calculation Model (Pencil Beam Model), a Neural Rad dose calculation method, or an RBM calculation method.
Preferably, in the step (6), the grid pitch in the y direction of the two-dimensional flux grid is adjusted to adjust the quadratic segmentation grid pitch.
A computing device, comprising:
one or more processors;
a memory; and
one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for a non-uniform grid distribution simulation linac treatment plan dose calculation method.
A computer readable storage medium storing one or more programs, the one or more programs comprising instructions adapted to be loaded from a memory and to execute the above-described non-uniform grid distribution simulated linac treatment plan dose calculation method.
The invention has the following beneficial effects:
the invention calculates the radiation dose through the non-uniform two-dimensional flux grid without adjusting the resolution of the grid, and can directly calculate the dose distribution of each grid according to the mechanical parameters (the position of a tungsten gate in treatment and the design shape and the position of each blade of the multi-blade collimator), so that the grid quantity is controllable. If the precision of the calculated dose compared with the actual measurement result cannot meet the preset requirement, the grid spacing in the y direction can be further adjusted, specifically, the grid division spacing in the y direction is further finely adjusted on the basis of the protruding and grooving division positions during secondary division to correct the precision of dose calculation, and the protruding and grooving leakage indexes of the corresponding grids can be further adjusted. Therefore, the dose distribution can be well matched with the actually measured result without additionally adding other correction methods to adjust the dose distribution. The method is effective in simulating the tungsten gate and the multi-leaf collimator in the conventional mainstream radiotherapy linear accelerator, so that the dose calculation precision is further improved, and meanwhile, the calculated amount is controllable to meet the actual clinical requirement.
In addition, the method provided by the invention is also suitable for smaller radiation fields.
Drawings
FIG. 1 is a flow chart of a method for calculating dose for a non-uniform grid distribution simulation linac treatment plan in a preferred embodiment of the present invention.
Fig. 2(a) is a top view of a multi-leaf collimator according to a preferred embodiment of the present invention.
Fig. 2(b) is a side view of a multi-leaf collimator in a preferred embodiment of the invention.
Fig. 2(c) is a schematic diagram of the y-direction segmentation of the two-dimensional flux grid in a preferred embodiment of the invention.
Fig. 3 is a schematic diagram of a two-dimensional flux grid in a preferred embodiment of the invention.
Detailed Description
The invention is further illustrated below with reference to examples and figures.
A dose calculation method for a non-uniform grid distribution simulation linear accelerator treatment plan comprises the following steps (the flow of which is shown in figure 1):
(1) setting non-uniform grid parameters 310, specifically including the following steps:
(i) setting the boundaries of the two-dimensional flux grid for dose calculation 311;
in an exemplary embodiment of the invention, the boundaries of the dose-calculated two-dimensional flux grid are determined by the maximum outer contour formed by the tungsten gate motion in each treatment plan, i.e. the boundary of the dose-calculated two-dimensional flux grid at the maximum outer contour formed by the tungsten gate motion in the treatment plan.
(ii) An initial grid spacing 312 in the y-direction (perpendicular to the direction of motion of the multi-leaf collimator) of the two-dimensional flux grid is initially segmented according to the thickness of the leaves of the multi-leaf collimator;
preferably, the grid spacing in the y-direction of the two-dimensional flux grid of the preliminary segmentation is consistent with the thickness of the leaf of the multi-leaf collimator corresponding thereto, as shown in fig. 2(c), and in the grid division in the y-direction of the two-dimensional flux grid, the grid spacing of the solid line part is consistent with the thickness of the multi-leaf collimator corresponding to each grid.
(iii) The grid spacing in the y direction of the two-dimensional flux grid is divided again according to the coupling position between the multi-leaf collimator pieces to obtain a quadratic division grid spacing 313 in the y direction;
fig. 2(a) is a top view of a multi-leaf collimator according to a preferred embodiment of the present invention, and fig. 2(b) is a side view of the multi-leaf collimator, wherein adjacent leaves of the multi-leaf collimator are provided with protrusions and/or grooves to couple the adjacent leaves, thereby preventing or reducing inter-leaf leakage transmission. It should be understood by those skilled in the art that fig. 2(b) is only an exemplary coupling method, and is not intended to limit the coupling method in the present invention. The present invention determines the position of the quadratic division of the grid spacing in the y-direction of the two-dimensional flux grid by means of protrusions (tongue) and/or notches (grooves), as shown by the dashed lines in fig. 2 (c).
(iv) Setting the grid spacing 314 in the two-dimensional flux grid x-direction (the direction of motion of the multi-leaf collimator); the spacing of adjacent grids in the x-direction of the two-dimensional flux grid is less than the value of the spacing when a pair of vanes are closed. Wherein the grid spacing in the x-direction of the two-dimensional flux grid may be a uniform or non-uniform grid. In one example embodiment, as shown in fig. 3, the grid in the x-direction of the two-dimensional flux grid is divided into equally spaced divisions;
(2) setting an initial flux value 320 corresponding to the grid according to the inter-chip leakage transmission measurement result;
flux values for inter-slice leakage into a TPS (radiation treatment plan) are defined based on the measured leakage rates, and beam flux is adjusted according to the area proportion of the occlusion parts in the corresponding grid.
In the two-dimensional flux grid, the flux value corresponding to each grid is influenced by the motion position of the multi-leaf collimator and factors such as transmission and radiation leakage among the leaves of the multi-leaf collimator. In one exemplary two-dimensional flux grid segmentation scheme shown in fig. 3, grids 34, 35, 44, 45, 54, 55, 64, and 65 radiation are not blocked by the multi-leaf collimator and no transmission or leakage occurs, so the grid flux value can be set to 100% at this position; the flux values of the grids 14, 15, 33, 36, 53, 56, 74, 75, 94, 95 are affected by the position of the multi-leaf collimator, and the radiation corresponding to the grids is partially blocked, so the grid flux values can be obtained by subtracting the remaining percentage of the blocked area, for example, the grid 14, the blocked area by the multi-leaf collimator is 35% of the total area of the grid, and the corresponding flux value can be set to 65% of the flux value of the grid 34; the grids 24, 25, 43, 46, 63, 66, 84, 85, etc. are affected by the position of the multi-leaf collimator movement and the degree of transmission and leakage between leaves, so both the shading area and the transmittance need to be considered in calculating the flux.
(3) Calling a dose calculation method according to the non-uniform grid parameters and the initial flux values corresponding to the grids, calculating to obtain the contribution of each grid to the total dose distribution, and finally overlapping the dose calculation results of the grids to obtain the dose 330 of the whole radiation field in the selected phantom;
the dose calculation method invoked in this embodiment may use various existing dose calculation methods, such as Monte Carlo dose calculation method (Monte Carlo), Pencil Beam calculation Model (Pencil Beam Model), Neural Rad dose calculation method, or RBM calculation method.
(4) Measuring the true dose 340 of the selected phantom in the field;
(5) comparing the actual dose with the overall difference of dose calculation, and judging whether the difference of the actual dose and the dose calculation is within a preset calculation precision range 350;
if the difference is within the preset calculation accuracy range, receiving the current grid segmentation parameters and flux values for dose calculation 351 of a subsequent patient treatment plan;
if the difference exceeds the preset calculation precision range, repeating the steps (6) - (7); until the difference between the dose calculation result and the real dose meets the preset precision;
(6) further adjusting the grid spacing of the two-dimensional flux grid in the y direction to obtain the optimized grid spacing in the y direction; and/or further adjusting the initial flux value corresponding to each grid to obtain an optimized flux value 360;
preferably, the adjusting the grid spacing in the y direction of the two-dimensional flux grid is to adjust the dividing position of the quadratic division grid, and the dividing position of the preliminarily divided y-direction grid is reserved; that is, the position of the dotted line dividing the y-direction grid in fig. 2(c) is fine-tuned, the two-dimensional flux grid after the re-tuning is called an equivalent grid, and the length after the tuning is called an equivalent length;
(7) according to the optimized grid parameters and the optimized flux values corresponding to the grids, a dose calculation method is called to calculate the contribution of each grid to the total dose distribution, and finally the dose calculation results of the grids are overlapped to obtain the dose 370 of the whole field in the selected phantom.
The present invention also provides a computing device comprising:
one or more processors;
a memory; and
one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for a non-uniform grid distribution simulated linac treatment plan dose calculation method, the method comprising the steps of:
(1) setting non-uniform grid parameters:
(i) setting the boundaries of a two-dimensional flux grid for dose calculation;
(ii) preliminarily dividing the initial grid spacing of the two-dimensional flux grid in the y direction according to the thickness of the blades of the multi-blade collimator;
(iii) the grid spacing of the two-dimensional flux grid in the y direction is divided again according to the coupling position between the multi-leaf collimator pieces to obtain a quadratic division grid spacing in the y direction;
(iv) setting grid spacing of a two-dimensional flux grid in the x direction;
(2) setting an initial flux value of a corresponding grid according to an inter-chip leakage transmission measurement result;
(3) calling a dose calculation method to calculate according to the non-uniform grid parameters and the initial flux values corresponding to the grids to obtain the contribution of each grid to the total dose distribution, and finally overlapping the dose calculation results of the grids to obtain the dose distribution of the whole radiation field in the selected die body;
(4) measuring the true dose of the selected die body under the radiation field;
(5) comparing the integral difference between the actual dose and the dose calculation, and judging whether the difference between the actual dose and the dose calculation is within a preset calculation precision range;
if the difference is within the preset calculation precision range, receiving the current grid segmentation parameters and flux values for dose calculation of the patient treatment plan;
if the difference exceeds the preset calculation precision range, repeating the steps (6) - (7); until the difference between the dose calculation result and the real dose meets the preset precision;
(6) further adjusting the grid spacing of the two-dimensional flux grid in the y direction to obtain the optimized grid spacing in the y direction; and/or further adjusting the initial flux value corresponding to each grid to obtain an optimized flux value;
(7) and according to the optimized grid parameters and the optimized flux values corresponding to the grids, calling a dose calculation method to calculate and obtain the contribution of each grid to the total dose distribution, and finally overlapping the dose calculation results of the grids to obtain the dose of the whole portal in the selected phantom.
The present invention also provides a computer readable storage medium storing one or more programs, the one or more programs comprising instructions adapted to be loaded from memory and execute the method for non-uniform grid distributed simulated linac treatment plan dose calculation, the method comprising the steps of:
(1) setting non-uniform grid parameters:
(i) setting the boundaries of a two-dimensional flux grid for dose calculation;
(ii) preliminarily dividing the initial grid spacing of the two-dimensional flux grid in the y direction according to the thickness of the blades of the multi-blade collimator;
(iii) the grid spacing of the two-dimensional flux grid in the y direction is divided again according to the coupling position between the multi-leaf collimator pieces to obtain a quadratic division grid spacing in the y direction;
(iv) setting grid spacing of a two-dimensional flux grid in the x direction;
(2) setting an initial flux value of a corresponding grid according to an inter-chip leakage transmission measurement result;
(3) calling a dose calculation method to calculate according to the non-uniform grid parameters and the initial flux values corresponding to the grids to obtain the contribution of each grid to the total dose distribution, and finally overlapping the dose calculation results of the grids to obtain the dose distribution of the whole radiation field in the selected die body;
(4) measuring the true dose of the selected die body under the radiation field;
(5) comparing the integral difference between the actual dose and the dose calculation, and judging whether the difference between the actual dose and the dose calculation is within a preset calculation precision range;
if the difference is within the preset calculation precision range, receiving the current grid segmentation parameters and flux values for dose calculation of the patient treatment plan;
if the difference exceeds the preset calculation precision range, repeating the steps (6) - (7); until the difference between the dose calculation result and the real dose meets the preset precision;
(6) further adjusting the grid spacing of the two-dimensional flux grid in the y direction to obtain the optimized grid spacing in the y direction; and/or further adjusting the initial flux value corresponding to each grid to obtain an optimized flux value;
(7) and according to the optimized grid parameters and the optimized flux values corresponding to the grids, calling a dose calculation method to calculate and obtain the contribution of each grid to the total dose distribution, and finally overlapping the dose calculation results of the grids to obtain the dose of the whole portal in the selected phantom.
Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second", "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
It should be understood that the various techniques described herein may be implemented in connection with hardware or software or, alternatively, with a combination of both. Thus, the methods and apparatus of the present invention, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium, wherein, when the program is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention.
By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. Computer storage media store information such as computer readable instructions, data structures, program modules or other data. Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. Combinations of any of the above are also included within the scope of computer readable media.
The embodiments described above are intended to facilitate one of ordinary skill in the art in understanding and using the present invention. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the embodiments described herein, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.
Claims (9)
1. A non-uniform grid distribution simulated linac treatment plan dose calculation method, adapted to be executed in a computing device, characterized by: the method comprises the following steps:
(1) setting non-uniform grid parameters:
(i) setting the boundaries of a two-dimensional flux grid for dose calculation;
(ii) preliminarily dividing the initial grid spacing of the two-dimensional flux grid in the y direction according to the thickness of the blades of the multi-blade collimator;
(iii) secondarily dividing the grid spacing of the two-dimensional flux grid in the y direction according to the coupling position between the multi-leaf collimator leaves to obtain the secondary division grid spacing in the y direction;
(iv) setting grid spacing of a two-dimensional flux grid in the x direction;
(2) setting an initial flux value of a corresponding grid according to an inter-chip leakage transmission measurement result;
(3) calling a dose calculation method to calculate according to the non-uniform grid parameters and the initial flux values corresponding to the grids to obtain the contribution of each grid to the total dose distribution, and finally overlapping the dose calculation results of the grids to obtain the dose distribution of the whole radiation field in the selected die body;
(4) measuring the true dose of the selected die body under the radiation field;
(5) comparing the integral difference between the actual dose and the dose calculation, and judging whether the difference between the actual dose and the dose calculation is within a preset calculation precision range;
if the difference is within the preset calculation precision range, receiving the current grid segmentation parameters and flux values for dose calculation of the patient treatment plan;
if the difference exceeds the preset calculation precision range, repeating the steps (6) to (7); until the difference between the dose calculation result and the real dose meets the preset precision;
(6) further adjusting the quadratic segmentation grid spacing of the two-dimensional flux grid in the y direction to obtain the optimized grid spacing in the y direction; further adjusting the initial flux value corresponding to each grid to obtain an optimized flux value;
(7) and according to the optimized grid parameters and the optimized flux values corresponding to the grids, calling a dose calculation method to calculate and obtain the contribution of each grid to the total dose distribution, and finally overlapping the dose calculation results of the grids to obtain the dose of the whole portal in the selected phantom.
2. The non-uniform grid distribution simulated linac treatment plan dose calculation method of claim 1, characterized by: in step (i), the boundaries of the two-dimensional flux grid for dose calculation are determined by the maximum outer contour formed by the tungsten gate motion in each treatment plan.
3. The non-uniform grid distribution simulated linac treatment plan dose calculation method of claim 1, characterized by: in step (ii), the grid spacing of the preliminarily segmented two-dimensional flux grid in the y direction is consistent with the thickness of the corresponding multi-leaf collimator leaf.
4. The non-uniform grid distribution simulated linac treatment plan dose calculation method of claim 1, characterized by: in step (iii), the grid spacing in the y-direction of the two-dimensional flux grid is sub-divided according to the position of the protrusions and the notches in the multi-leaf collimator.
5. The non-uniform grid distribution simulated linac treatment plan dose calculation method of claim 1, characterized by: in step (iv), the grid segmentation in the x-direction of the two-dimensional flux grid is an equidistant segmentation.
6. The non-uniform grid distribution simulated linac treatment plan dose calculation method of claim 1, characterized by: in step (iv), the spacing between adjacent grids in the x-direction of the two-dimensional flux grid is less than the value of the spacing when a pair of vanes are closed.
7. The non-uniform grid distribution simulated linac treatment plan dose calculation method of claim 1, characterized by: in the step (3), the dose calculation method is a Monte Carlo dose calculation method, a pencil beam calculation model, a neuroalRad dose calculation method or an RBM calculation method.
8. A computing device, comprising:
one or more processors;
a memory; and
one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by one or more processors, the one or more programs comprising instructions for implementing the non-uniform grid distribution simulation linac treatment planning dose calculation method of any of claims 1-7 above.
9. A computer readable storage medium storing one or more programs, the one or more programs comprising instructions adapted to be loaded from a memory and to execute the non-uniform grid distribution simulated linac treatment plan dose calculation method of any of claims 1-7 above.
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