Proton spin intensity modulated radiation method and apparatus

Abstract

The application belongs to the field of medical physics simulation calculation, and provides a proton rotating intensity modulated radiation method and equipment, the method comprising the following steps: S1, performing beam spot filling on a target region; S2, dividing the beam spot into different fields according to the equivalent water depth in the beam spot incidence process; and S3, continuously outputting the proton beam to complete the rotating intensity modulated radiation treatment in the accelerator rotating process. The technical scheme of the application is a new proton rotating intensity modulated radiation method, which provides more possibilities for the development of the proton rotating intensity modulated radiation treatment technology.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of medical physics simulation calculation, and particularly relates to a proton rotational intensity modulated radiation method and device. BACKGROUND

[0002] In recent years, proton therapy has attracted the attention of many researchers because it has better target region conformality and can better treat deep tumors. After entering the human body, protons form a Bragg peak at the end of the range, and most of the energy is deposited at the Bragg peak, and more accurate and conformal radiation therapy can be achieved by adjusting the energy to make the Bragg peak fall at the specified position.

[0003] Proton rotational intensity modulated therapy is concerned because of its ability to continuously output proton beams during gantry rotation. Compared with intensity modulated proton therapy (IMPT), proton rotational intensity modulation can significantly reduce damage to critical organs and has the potential advantage of providing robust plan quality. The present application proposes a method and device for realizing proton rotational intensity modulated radiation by filling the target region with beam spots and dividing the beam spots into different angle fields. SUMMARY

[0004] To solve the above technical problems, the present application provides a proton rotational intensity modulated radiation method and device to solve the problems in the prior art. The technical solution adopted by the present application is as follows:

[0005] A proton rotational intensity modulated radiation method, comprising the following steps:

[0006] Step S1, converting the voxel index contained in the target region into three-dimensional coordinates with the isocenter as the origin, and interpolating the target region coordinates according to the beam spot spacing to obtain the coordinate values of the filled beam spots;

[0007] Step S2, obtaining the equivalent water depth of each beam spot by path tracking method, and dividing the beam spots into different fields according to the equivalent water depth under different angle incidence of the beam;

[0008] Step S3, continuously outputting proton beams during accelerator rotation.

[0009] Further, step S1 comprises:

[0010] Step S1.1, coordinate conversion, when importing a case into MATLAB software, the voxels contained in the target region can be obtained, and the three-dimensional coordinate values of the target region voxels with the isocenter as the origin are obtained by exporting the subscript index of the voxels, the CT resolution of the voxels and the coordinate values of the isocenter, denoted as ind_X i , ind_Y i , ind_Z iis the subscript index of the i th voxel, ct.x, ct.y, ct.z represent the resolution of CT, isoCenter is the coordinate value of the isocenter with the first voxel in the upper left corner of CT as the coordinate origin, and the coordinate value of the i th voxel with the isocenter as the origin is:

[0011] X i =ind_X i *ct.x-isoCenter(1)

[0012] Y i =ind_Y i *ct.y-isoCenter(2)

[0013] Z i =ind_Z i *ct.z-isoCenter(3)

[0014] S1.2, the beam spot fills the target area, selects the beam spot whose Bragg peak deposition position is on the path of the incident and exit target area, covers the target area in the incident depth direction through the Bragg peak of the beam spot on the path, obtains the target area voxel three-dimensional coordinate value through step S1.1, and the beam spot spacing is bw=5mm. The beam spot coordinate value is obtained by interpolating the target area voxel coordinates:

[0015] [x,y,z]=unique(bw*round([XYZ] / bw))

[0016] Wherein, the round function is used to round the numerical value to the nearest integer; the unique function is used to obtain unique values.

[0017] Further, step S2 includes:

[0018] Step S2.1, obtaining the equivalent water depth, calculating the equivalent water depth of the beam incident into the human body to the beam spot coordinate obtained in step S1.2:

[0019] Equivalent water depth=L·ρ

[0020] Wherein, L represents the length of the ray passing through the voxel, and p represents the tissue density corresponding to the voxel;

[0021] Step S2.2, dividing the beam spot into different fields, calculating the equivalent water depth of each 5° field in 360° to the beam spot coordinate obtained in step S1.2 through step S2.1, and dividing the beam spots with the same equivalent water depth into the same field, and the energy is selected as the energy closest to the Bragg peak deposition position of the equivalent water depth value.

[0022] A proton rotating intensity modulated radiation device, comprising a beam spot filling processing module, a beam spot division processing module and a proton output processing module, wherein:

[0023] a beam spot filling processing module fills the target region with beam spots;

[0024] a beam spot division processing module divides the beam spots into different fields according to the equivalent water depth in the beam spot incidence process;

[0025] a proton output processing module continuously outputs the proton beam during the accelerator rotation process.

[0026] The present application has the following beneficial effects: the present application uses a path tracking function to calculate the equivalent water depth of the beam spot, and through filling the target region with beam spots and then dividing the beam spots into different fields for treatment plan delivery, the present application can realize proton rotation intensity modulation radiotherapy, can significantly improve the accuracy, and can ensure the accuracy and uniformity of target region coverage, and through dividing the beam spots into different fields according to the equivalent water depth, the present application realizes accurate delivery of the proton beam. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 a method flowchart of the present application;

[0028] Figure 2 a distribution diagram of a brain case obtained by filling the target region with beam spots according to example 1 of the present application;

[0029] Figure 3 a dose distribution diagram of a brain case obtained according to example 1 of the present application;

[0030] Figure 4 a dose-volume histogram of a brain case obtained according to example 1 of the present application. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below. Figures 1-4 The technical solutions in the embodiments of the present application will be clearly and completely described below.

[0032] As Figure 1 A proton rotation intensity modulation radiotherapy method, specifically comprising the following steps:

[0033] Step S1, converting the voxel index contained in the target region into three-dimensional coordinates with the isocenter as the origin, and interpolating the target region coordinates according to the beam spot spacing to obtain the coordinate values of the required filling beam spots.

[0034] Step S1.1, coordinate conversion, when importing the case to MATLAB software, the voxel contained in the target region can be obtained, and the three-dimensional coordinate value of the target region voxel with the isocenter as the origin can be obtained by exporting the subscript index of the voxel, the CT resolution of the voxel and the coordinate value of the isocenter. Let ind_X i , ind_Y i , ind_Z i be the subscript index of the i-th voxel, ct.x, ct.y, ct.z represent the resolution of CT, and isoCenter be the coordinate value of the isocenter with the first voxel in the upper left corner of CT as the coordinate origin. Then the coordinate value of the i-th voxel with the isocenter as the origin is,

[0035] X i =ind_X i *ct.x-isoCenter (1)

[0036] Y i =ind_Y i *ct.y-isoCenter (2)

[0037] Z i =ind_Z i *ct.z-isoCenter (3)

[0038] Step S1.2, beam spot filling target region, the position of the original beam spot in the target region energy deposition, i.e. the energy of the beam spot, is determined by tracking the beam incident and exit position of the target region, i.e. the equivalent water depth (WET) after the beam enters the human body, under the condition of knowing the target region coordinates and beam coordinates. The beam spot with Bragg peak deposition position on the path between the incident and exit target region is selected, and the Bragg peak of the beam spot on the path is used to cover the target region in the incident depth direction. The present application first proposes beam spot filling target region. Figure 2 is a brain case, the prescribed dose is 30Gy / 15 times, and on the basis of obtaining the three-dimensional coordinate value of the target region voxel by step S1.1, the beam spot spacing is set as bw=5mm, and the coordinates of the target region voxel are interpolated to obtain the beam spot coordinate value.

[0039] [x,y,z]=unique(bw*round([XYZ] / bw))

[0040] Wherein, the formula uses MATLAB language, the round function is used to round the numerical value to the nearest integer; the unique function is used to obtain unique values.

[0041] Step S2, obtain the equivalent water depth (WET) of each beam spot by the path tracking method, and divide the beam spots into different fields according to the WET of the beam under different incident angles.

[0042] Step S2.1, obtaining water equivalent thickness (WET), high-energy proton beam irradiation into water or medium, energy deposition at the end of the range exists a Bragg peak. In proton therapy, the non-uniform medium has a significant impact on the Bragg peak of the proton beam, so the range of the beam incident on the non-uniform human body is converted into the equivalent water depth to select a more accurate energy to let the Bragg peak deposit in a more accurate position. The invention calculates the equivalent water depth thickness of the beam spot coordinates obtained in step S1.2 from the path tracking function.

[0043] Water equivalent thickness = L·ρ

[0044] Wherein, L represents the length of the ray passing through the voxel, and ρ represents the tissue density corresponding to the voxel.

[0045] Step S2.2, dividing the beam spot into different fields, when the beam is incident on the human body from different angles to reach the same beam spot coordinates obtained in step S1.2, the WET value is not equal. In order to realize the continuous output of the proton beam in the rotating intensity modulated radiotherapy, the energy of each field is required to be equal. Step S2.1 calculates the WET of the beam spot coordinates of every 5° field in 360°, and divides the beam spot with the same WET into the same field, and the energy is selected as the energy closest to the Bragg peak deposition position.

[0046] Step S3, the accelerator rotates to continuously output the proton beam to complete the rotating intensity modulated radiotherapy.

[0047] The implementation of proton rotating intensity modulated radiotherapy has realized the continuous output of the proton beam during the rotation of the accelerator. The invention only adjusts the number and energy of each beam spot, and can also complete the delivery of proton rotating intensity modulated radiotherapy.

[0048] The present application also relates to a proton rotating intensity modulated radiotherapy device, comprising a beam spot filling processing module, a beam spot division processing module and a proton output processing module.

[0049] The beam spot filling processing module fills the beam spot in the target area.

[0050] The beam spot division processing module divides the beam spot into different fields according to the water equivalent thickness (WET) in the beam spot incident process.

[0051] The proton output processing module continuously outputs the proton beam during the rotation of the accelerator to complete the rotating intensity modulated radiotherapy.

[0052] The above described embodiments are only to illustrate the preferred modes of the present application, and are not intended to limit the scope of the present application. Any modification, variation, modification, and replacement of the technical solutions of the present application made by those skilled in the art without departing from the design spirit of the present application shall fall within the protection scope determined by the claims of the present application.

Claims

1. A method for intensity-modulated proton radiation, characterized in that, Includes the following steps: Step S1: Convert the voxel indexes contained in the target area into three-dimensional coordinates with the isocenter point as the origin, and interpolate the target area coordinates according to the beam spot spacing to obtain the coordinate values ​​of the filling beam spot. Step S2: Obtain the equivalent water depth thickness of each beam spot using the path tracing method, and divide the beam spot into different firing fields based on the equivalent water depth thickness when the beam is incident from different angles. Step S3: The proton beam is continuously output during the accelerator rotation process; Step S1.1: Coordinate Transformation. When importing the case into MATLAB software, the voxels contained in the target area are obtained. By exporting the voxel subscript index, voxel CT resolution, and isocenter coordinates, the three-dimensional coordinates of the target area voxels with the isocenter as the origin are obtained. This is denoted as ind_X. i ind_Y i ind_Z i Here, ct.x, ct.y, and ct.z represent the CT resolution, isoCenter is the coordinate value of the isocenter with the first voxel at the top left corner of the CT as the origin, and the coordinate value of the i-th voxel with the isocenter as the origin is: X i =ind_X i *ct.x-isoCenter(1) AND i =ind_Y i *ct.y-isoCenter(2) Z i =ind_Z i *ct.z-isoCenter(3) S1.2, Beam spot filling of the target area: Select a beam spot with the Bragg peak deposition location on the path between the incident and exit target areas. The Bragg peak of the beam spot on this path covers the target area in the direction of the incident depth. The three-dimensional coordinate values ​​of the target area voxels are obtained through step S1.

1. With a beam spot spacing of bw = 5 mm, the coordinates of the target area voxels are interpolated to obtain the beam spot coordinate values. [x,y,z]=unique(bw*round([XYZ] / bw)) The `round` function rounds a number to the nearest integer; the `unique` function obtains a unique value.

2. The proton rotation intensity-modulated radiography method as described in claim 1, characterized in that, Step S2 includes: Step S2.1: Obtain the equivalent water depth thickness and calculate the equivalent water depth thickness from the incident beam on the human body to the beam spot coordinates obtained in step S1.2: Equivalent water depth thickness = L·ρ Where L represents the length of the ray passing through the voxel, and ρ represents the tissue density corresponding to the voxel; Step S2.2: Divide the beams into different radiation fields. Calculate the equivalent water depth thickness of the beam coordinates obtained in step S1.2 for every 5° of radiation field in 360° using step S2.

1. Then, divide the beams with the same equivalent water depth thickness into the same radiation field. The energy selected is the energy whose equivalent water depth thickness value is closest to the deposition position of the Bragg peak.

3. A proton rotation intensity-modulated radiation device, employing the proton rotation intensity-modulated radiation method as described in claim 1, characterized in that, It includes a beam spot filling processing module, a beam spot division processing module, and a proton output processing module, wherein: The beam spot filling module fills the target area with beam spots. The beam spot segmentation and processing module divides the beam spot into different firing fields based on the equivalent water depth thickness during the beam spot incident process; The proton output processing module continuously outputs a proton beam during the accelerator's rotation.

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