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MOPSA35 |
Concept of Scanning Detector for Measurement of Ejected Medical Hadron Beam Profile | |
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Funding: The work is supported by the Russian Science Foundation, project No. 21-79-00252. Hadron radiation therapy with proton beams and light ions provides the most precise irradiation of tumor with a significant dose reduction in critical organs and healthy tissue areas that is caused by heavy charged particles property to release maximal part of energy in the end of the particles range (Bragg peak). Determination of spatial beam parameters in process of hadron radiation therapy facilities development and modernization is highly topical. One of the main requirements for the devices measuring therapeutic hadron beams is the possibility to provide nondestructive determination of the beam parameters in real-time mode. This study propose new method to measure particle flux intensity transverse distribution based on mathematical reconstruction of the multiangular hadron beam scanning data. Suggested approach allows online beam intensity distribution measurement with relatively high resolution, without any consumable materials. |
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MOPSA36 |
Formation of Ejected High-Energy Therapeutic Electron Beam With 3D Printed Test Samples | |
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Funding: The work is supported by the Russian Science Foundation, project No. 19-79-10014. Electron beam using for radiation therapy allows achievement of good therapeutic and cosmetic treatment results. It is necessary to improve the methods high-energy therapeutic electron beam forming to increase the efficiency this treatment. Specially designed units, known as compensators, a typically used to obtain a complex dose distribution in the patient’s body. Compensators are usually set perpendicularly to electron beam axis at particular distance from patient and used to form depth dose distribution. In this study authors proposed to use polymer compensators made by fused deposition modeling to form dose field of electron clinical accelerators. Applicability of this approach was investigated in series of physical experiments and Monte Carlo numerical simulations. Obtained results showed that therapeutic electron beams of 6-12 MeV could be modulated effectively using polymer compensators. Developed model for numerical simulations allows estimating of electron beam dose distributions modified by polymer absorbers and choosing compensators’ geometrical parameters for the particular task. |
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MOPSA37 |
Determination of Minimal Acceptable Sizes of Collimation Hole in Plastic Sample Forming Ejected Therapeutic High-Energy Electron Beam | |
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Funding: The work is supported by the Ministry of Science and Higher Education of the Russian Federation within agreement 075-15-2021-271, project No. MK-3481.2021.4 Electron beams are widely applicable for the tasks of the radiotherapy. These applications provides good therapeutic results for the treatment of a wide range of malignant neoplasms. The increased requirements for the accuracy of dose delivery make the issue of the complex radiation fields’ formation during radiation therapy sessions urgent. Moreover, formation of patient-specific dose fields is often demanded. Collimators of individual complex shapes can be produced using 3D printing. This study is aimed at investigating the limitations of the minimum size of collimation holes, allowing adequate electron beam shaping. The limitations can be caused by electron scattering at the edges of plastic absorbers collimation holes that causes gradual dose decreasing instead of sharp one. For experimental investigation of this effect, special test sample was designed and made. This sample is rectangular parallelepiped with 12 round through holes with different diameters. Experiments was performed with medical electron beam. Dosimetry films was used to measure transverse profiles formed by each collimation hole. Obtained results showed that 12 MeV electron beam can be effectively shaped with the collimation holes with diameter higher than 9 mm. |
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MOPSA38 |
Geant4 Based Numerical Model of Accelerator for Simulation of High Energy Therapeutic Electron Beam Parameters | |
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Funding: The work is supported by the Russian Science Foundation, project No. 19-79-10014. The main aim of radiotherapy is to destroy malignant cells by ionizing radiation with minimal impact on healthy tissues. A number of studies aims to development of personalized methods for the radiation field formation. One of the possible approach is 3D printing of individually shaped compensators. To choose geometrical parameters of these samples numerical simulations is demand. Monte Carlo simulations for calculation of absorbed dose is based on fundamental physical principles of particles interaction with a propagation medium. This approach allows precision simulating of electron beam propagation in radiotherapy tasks. Practical application of Monte Carlo method requires numerical model for predicting dose distribution in the absorbers based on experimental data. The most suitable parameters for this purpose is the depth dose distributions measured in water phantom along electron beam’s central axis for energies corresponding to particular clinical accelerator. The dose distribution’s curve shape is caused by energy spectrum of the electron beam which influenced by many experimental parameters, e.g. beam injection system geometry. Therefore, the aim of this study is to develop numerical model of clinical linear accelerator¿s electron beam accounting ejection system parameters for assessment of depth dose distribution and transverse profiles in water phantom. |
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WEPSC38 |
Determination of Optimal Number of Beam Projections for Scanning Beam Profile Detector Development | |
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Funding: The work is supported by the Ministry of Science and Higher Education of the Russian Federation within agreement 075-15-2021-273, project No. MK-4867.2021.1.2. One of important spatial parameter of particle beams is intensity transverse distribution. Measuring systems for obtaining this parameter should meets following requirements: sufficient spatial resolution; short data collection and processing time; minimum beam destruction during measurement. Most of currently used approaches do not correspond to all of these requirements simultaneously. Authors proposed method based on reconstruction inverse Radon transformation of the data obtained by multiple wire scanning of the beam at different angles with a fixed angle step. This study aims to determine optimal number of beam scans (beam projection). For this aim, test intensity transverse distribution typical for radiation beams was chosen and reconstructed by proposed method. The standard deviation and Euclidean distance were used as criteria for quantitatively assessment of the reconstructed distribution reliability. Based on data obtained, we find an equation for calculation of optimal number of beam projections. With this optimal number, reconstruction results are still reliable, while number of beam scans and, consequently, measurement time are minimal. |
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