Ion beam radiotherapy dosage verification method based on water equivalent coefficients

Abstract

The invention relates to an ion beam radiotherapy dosage verification method based on water equivalent coefficients. The ion beam radiotherapy dosage verification method based on the water equivalent coefficients includes the following steps that A, CT image data of a cancer patient are obtained, a treatment planning system (TPS) is utilized for plan design according to a CT-water equivalent coefficient transformation curve, and ion beam radiation parameters are recorded after the plan is determined; B, a virtual three-dimensional water phantom CT image is generated based on the water equivalent coefficients, the ion beam radiation parameters are transplanted to the water phantom through the TPS, dosage optimal computation is carried out again, and three-dimensional rasterization dose distribution in the water phantom is obtained; C, an ionization chamber is placed at an interest point in the three-dimensional water phantom, interpolating calculation is carried out in the three-dimensional rasterization dose distribution according to the three-dimensional coordinates of the sensitive volume of the ionization chamber in the water phantom, and planned dosage of the interest point is obtained; D, the ion beam radiation parameters designed as planned control a medical heavy-ion accelerator to perform simulated irradiation on the water phantom, and the measured absolute dosage value of the interest point for the ionization chamber in the water phantom is compared with the planned dosage.

Description

technical field

[0001] The invention relates to the field of ion beam radiation therapy, in particular to a method for verifying dose of ion beam radiation therapy plan based on tissue water equivalent coefficient. Background technique

[0002] The dose calculation in the treatment plan of modern conventional radiation therapy (X-ray, electron beam, gamma knife, etc.) is based on the CT value obtained from the computed tomography (CT) scan to establish the CT-electron density conversion curve, and then proceed according to the converted tissue density. Tissue inhomogeneity dose optimization calculation, so as to obtain the dose distribution of radiation treatment plan. The main reason is that the principle of CT imaging is the interaction between x-rays and matter, that is, the CT value corresponds to the linear attenuation coefficient, and the linear attenuation coefficient is related to the type of action and the electron density of the tissue. In view of the fact that th...

Examples

Embodiment 1

[0038] Example 1: see figure 1 , a method for verifying the dose of ion beam radiotherapy based on the water equivalence coefficient, comprising the following steps:

[0039] A: Obtain CT image data of tumor patients, use TPS to plan and design according to the CT-water equivalent coefficient conversion curve, and record ion beam radiation parameters after the plan is confirmed;

[0040] B: Generate a virtual three-dimensional water phantom CT image based on the water equivalent coefficient, use TPS to transplant the ion beam radiation parameters to the water phantom, re-calculate the dose optimization, and obtain the three-dimensional grid dose distribution in the water phantom;

[0041] C: Put the ionization chamber into the position of the interest point in the three-dimensional water phantom, perform interpolation calculation in the three-dimensional gridded dose distribution according to the three-dimensional coordinates of the sensitive volume of the ionization chamber i...

Embodiment 2

[0043] Example 2: see figure 2, is a flow chart of step A of the ion beam radiotherapy dose verification method based on the water equivalent coefficient of the present invention, as a further improvement of the ion beam radiotherapy dose verification method based on the water equivalent coefficient, the step A includes :

[0044] A1: According to the contour data of the CT image, perform three-dimensional image reconstruction;

[0045] A2: Design the field according to the ion beam irradiation method, configure the machine parameters, and configure the planning constraints.

[0046] A3: Use the ion beam dose calculation model based on the CT-water equivalent coefficient conversion curve to optimize the calculation.

[0047] Record the ion beam radiation parameters after the planned evaluation. All the other steps are the same as in Example 1.

Embodiment 3

[0048] Example 3: image 3 , is the step flow chart of step B of the ion beam radiotherapy dose verification method based on the water equivalent coefficient of the present invention, as a further improvement of the ion beam radiotherapy dose verification method based on the water equivalent coefficient, the step B includes :

[0049] B1: Use the CT-water equivalent coefficient conversion curve to obtain the maximum water equivalent length corresponding to the maximum distance from the incident skin to the tumor target area in the BEV direction in the CT image. CT images of the virtual water phantom were generated in TPS according to the rule that the side length of the circumscribed rectangle of the maximum radiation field contour of the tumor target area expanded 5cm.

[0050] B2: Use TPS to transplant the ion beam radiation parameters to the CT image of the water phantom, re-calculate the dose optimization, and obtain the three-dimensional grid dose distribution in the wat...

technical field

[0001] The invention relates to the field of ion beam radiation therapy, in particular to a method for verifying dose of ion beam radiation therapy plan based on tissue water equivalent coefficient. Background technique

[0002] The dose calculation in the treatment plan of modern conventional radiation therapy (X-ray, electron beam, gamma knife, etc.) is based on the CT value obtained from the computed tomography (CT) scan to establish the CT-electron density conversion curve, and then proceed according to the converted tissue density. Tissue inhomogeneity dose optimization calculation, so as to obtain the dose distribution of radiation treatment plan. The main reason is that the principle of CT imaging is the interaction between x-rays and matter, that is, the CT value corresponds to the linear attenuation coefficient, and the linear attenuation coefficient is related to the type of action and the electron density of the tissue. In view of the fact that th...

Examples

Embodiment 1

[0038] Example 1: see figure 1 , a method for verifying the dose of ion beam radiotherapy based on the water equivalence coefficient, comprising the following steps:

[0039] A: Obtain CT image data of tumor patients, use TPS to plan and design according to the CT-water equivalent coefficient conversion curve, and record ion beam radiation parameters after the plan is confirmed;

[0040] B: Generate a virtual three-dimensional water phantom CT image based on the water equivalent coefficient, use TPS to transplant the ion beam radiation parameters to the water phantom, re-calculate the dose optimization, and obtain the three-dimensional grid dose distribution in the water phantom;

[0041] C: Put the ionization chamber into the position of the interest point in the three-dimensional water phantom, perform interpolation calculation in the three-dimensional gridded dose distribution according to the three-dimensional coordinates of the sensitive volume of the ionization chamber i...

Embodiment 2

[0043] Example 2: see figure 2, is a flow chart of step A of the ion beam radiotherapy dose verification method based on the water equivalent coefficient of the present invention, as a further improvement of the ion beam radiotherapy dose verification method based on the water equivalent coefficient, the step A includes :

[0044] A1: According to the contour data of the CT image, perform three-dimensional image reconstruction;

[0045] A2: Design the field according to the ion beam irradiation method, configure the machine parameters, and configure the planning constraints.

[0046] A3: Use the ion beam dose calculation model based on the CT-water equivalent coefficient conversion curve to optimize the calculation.

[0047] Record the ion beam radiation parameters after the planned evaluation. All the other steps are the same as in Example 1.

Embodiment 3

[0048] Example 3: image 3 , is the step flow chart of step B of the ion beam radiotherapy dose verification method based on the water equivalent coefficient of the present invention, as a further improvement of the ion beam radiotherapy dose verification method based on the water equivalent coefficient, the step B includes :

[0049] B1: Use the CT-water equivalent coefficient conversion curve to obtain the maximum water equivalent length corresponding to the maximum distance from the incident skin to the tumor target area in the BEV direction in the CT image. CT images of the virtual water phantom were generated in TPS according to the rule that the side length of the circumscribed rectangle of the maximum radiation field contour of the tumor target area expanded 5cm.

[0050] B2: Use TPS to transplant the ion beam radiation parameters to the CT image of the water phantom, re-calculate the dose optimization, and obtain the three-dimensional grid dose distribution in the wat...

Images