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...

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Problems solved by technology

[0011] Disadvantages of the prior art: 1. Conventional radiotherapy plan calculations are based on CT-tissue electron density curves, and ion beam dose calculations are not applicable

2 For conventional absolute dose verification, the phantom inserted into the ionization chamber must be scanned by CT to obtain the actual electron density, which increases the cost and time

[0012] In the absolute dose verification of conventional radiotherapy plans, the position of the ionization chamber cannot be changed after it is inserted into the solid phantom, and the metal electrodes of the ionization chamber will affect the CT electron density curve of the phantom, so there are limitations in the verification range and the dose calculation accuracy of the measured points

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