Simulation Design of Three Dimensional Ionization Chamber Array for Carbon Ion Therapy Based on Geant4

As an important part of radiation therapy quality assurance, dose verification can verify the accuracy of the treatment dose to the patient’s tumor target area before treatment. At present, the dose verification technology has developed to the stage of three-dimensional dose verification. However,...

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Main Author: LIAO Feng;HE Sanjun;ZHANG Shuang;LUO Wan;LIU Liyan;ZHAO Xiuliang
Format: Article
Language:English
Published: Editorial Board of Atomic Energy Science and Technology 2023-02-01
Series:Yuanzineng kexue jishu
Subjects:
Online Access:https://www.aest.org.cn/CN/10.7538/yzk.2022.youxian.0236
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author LIAO Feng;HE Sanjun;ZHANG Shuang;LUO Wan;LIU Liyan;ZHAO Xiuliang
author_facet LIAO Feng;HE Sanjun;ZHANG Shuang;LUO Wan;LIU Liyan;ZHAO Xiuliang
author_sort LIAO Feng;HE Sanjun;ZHANG Shuang;LUO Wan;LIU Liyan;ZHAO Xiuliang
collection DOAJ
description As an important part of radiation therapy quality assurance, dose verification can verify the accuracy of the treatment dose to the patient’s tumor target area before treatment. At present, the dose verification technology has developed to the stage of three-dimensional dose verification. However, the existing clinical dose verification tools cannot meet the demand for three-dimensional dose verification in heavy ion therapy. In order to quickly and accurately realize three-dimensional dose verification of carbon ion therapy plan, a three-dimensional ionization chamber array was designed by using plexiglass PMMA(polymethyl methacrylate) as the ionization chamber wall and water equivalent phantom. And the structural design of the three-dimensional ionization chamber array was thoroughly studied and verified by Geant4 software. Firstly, by simulating the depth dose distribution of carbon ion beam deposited in water and PMMA phantom with different energies, the distal range ratio of the Bragg peak of the carbon ion beam in water and PMMA phantom was calculated, and the water equivalent thickness factor of PMMA phantom was characterized. Its value is 1.151. Then the effects of the spacing between adjacent ionization chambers and the signal leads on the accuracy of the dose measurement in the three-dimensional ionization chamber array were investigated. The signal crosstalk between adjacent ionization chambers mainly originates from the front ionization chamber, and the degree of crosstalk is inversely proportional to the spacing, the degree of crosstalk accounts for 3% of the dose within the ionization chamber at spacing of 1 mm, and the crosstalk effect can be completely eliminated at spacing of 30 mm. And the interference effect of the signal leads on the dose within the rear ionization chamber is about 1%. Finally, the dose distribution of 100 MeV/u and 200 MeV/u carbon ion beams deposited in the three-dimensional ionization chamber array was simulated, and the distal range of the Bragg peak was obtained in which the carbon ion beam was deposited. It has good agreement compared to the distal range of the Bragg peak in the PMMA phantom, and the deviation is 0.5 mm. The research show that the three-dimensional ionization chamber array can realize the three-dimensional dose verification of heavy ion therapy at the same time, and provides a reference for the development of three-dimensional ionization chamber array. The quality assurance level of carbon ion therapy should be further improved.
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spelling doaj.art-5297aef002944c718c08ef595b53060d2023-03-16T07:16:16ZengEditorial Board of Atomic Energy Science and TechnologyYuanzineng kexue jishu1000-69312023-02-01572372378Simulation Design of Three Dimensional Ionization Chamber Array for Carbon Ion Therapy Based on Geant4LIAO Feng;HE Sanjun;ZHANG Shuang;LUO Wan;LIU Liyan;ZHAO Xiuliang0School of Nuclear Science and Technology, University of South China, Hengyang 421001, China As an important part of radiation therapy quality assurance, dose verification can verify the accuracy of the treatment dose to the patient’s tumor target area before treatment. At present, the dose verification technology has developed to the stage of three-dimensional dose verification. However, the existing clinical dose verification tools cannot meet the demand for three-dimensional dose verification in heavy ion therapy. In order to quickly and accurately realize three-dimensional dose verification of carbon ion therapy plan, a three-dimensional ionization chamber array was designed by using plexiglass PMMA(polymethyl methacrylate) as the ionization chamber wall and water equivalent phantom. And the structural design of the three-dimensional ionization chamber array was thoroughly studied and verified by Geant4 software. Firstly, by simulating the depth dose distribution of carbon ion beam deposited in water and PMMA phantom with different energies, the distal range ratio of the Bragg peak of the carbon ion beam in water and PMMA phantom was calculated, and the water equivalent thickness factor of PMMA phantom was characterized. Its value is 1.151. Then the effects of the spacing between adjacent ionization chambers and the signal leads on the accuracy of the dose measurement in the three-dimensional ionization chamber array were investigated. The signal crosstalk between adjacent ionization chambers mainly originates from the front ionization chamber, and the degree of crosstalk is inversely proportional to the spacing, the degree of crosstalk accounts for 3% of the dose within the ionization chamber at spacing of 1 mm, and the crosstalk effect can be completely eliminated at spacing of 30 mm. And the interference effect of the signal leads on the dose within the rear ionization chamber is about 1%. Finally, the dose distribution of 100 MeV/u and 200 MeV/u carbon ion beams deposited in the three-dimensional ionization chamber array was simulated, and the distal range of the Bragg peak was obtained in which the carbon ion beam was deposited. It has good agreement compared to the distal range of the Bragg peak in the PMMA phantom, and the deviation is 0.5 mm. The research show that the three-dimensional ionization chamber array can realize the three-dimensional dose verification of heavy ion therapy at the same time, and provides a reference for the development of three-dimensional ionization chamber array. The quality assurance level of carbon ion therapy should be further improved.https://www.aest.org.cn/CN/10.7538/yzk.2022.youxian.0236carbon ion therapythree-dimensional ionization chamber arraygeant4three-dimensional dose verification
spellingShingle LIAO Feng;HE Sanjun;ZHANG Shuang;LUO Wan;LIU Liyan;ZHAO Xiuliang
Simulation Design of Three Dimensional Ionization Chamber Array for Carbon Ion Therapy Based on Geant4
Yuanzineng kexue jishu
carbon ion therapy
three-dimensional ionization chamber array
geant4
three-dimensional dose verification
title Simulation Design of Three Dimensional Ionization Chamber Array for Carbon Ion Therapy Based on Geant4
title_full Simulation Design of Three Dimensional Ionization Chamber Array for Carbon Ion Therapy Based on Geant4
title_fullStr Simulation Design of Three Dimensional Ionization Chamber Array for Carbon Ion Therapy Based on Geant4
title_full_unstemmed Simulation Design of Three Dimensional Ionization Chamber Array for Carbon Ion Therapy Based on Geant4
title_short Simulation Design of Three Dimensional Ionization Chamber Array for Carbon Ion Therapy Based on Geant4
title_sort simulation design of three dimensional ionization chamber array for carbon ion therapy based on geant4
topic carbon ion therapy
three-dimensional ionization chamber array
geant4
three-dimensional dose verification
url https://www.aest.org.cn/CN/10.7538/yzk.2022.youxian.0236
work_keys_str_mv AT liaofenghesanjunzhangshuangluowanliuliyanzhaoxiuliang simulationdesignofthreedimensionalionizationchamberarrayforcarboniontherapybasedongeant4