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Evaluation of Dose Change to Brain Tumor in Proton Therapy by Utilizing Magnetic Field

Karbalaee, Faezeh | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56422 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Vosoughi, Naser; Salimi, Ehsan
  7. Abstract:
  8. The use of protons and charged particles such as carbon in the treatment of cancerous tumors is one of the new methods of external radiation therapy. Proton therapy can achieve almost the same tumor dose coverage as traditional photon therapy with a greatly reduced dose to the normal organ. The radiation deviations caused by the magnetic field are an effective factor in reducing the dose of vital organs without sacrificing the dose coverage of tumors; Therefore, a new method of proton therapy, called magnetic field-modulated proton therapy, has been proposed, in which the Bragg peak positions of proton beams can be modulated under the cover of predesigned magnetic fields inside cancer patients. In this study, by using the Monte Carlo simulation method of Geant4 simulator software, we have modeled and investigated the parameters of the spot scanning system of the Medastron center based on the beam data library. First, the beam radiation of 10 single-energy and one-directional proton sources with specifications according to the radiation data library of the Medastron ion therapy system, in the energy range of 62.4 to 252.7 MeV, was simulated in an ideal water phantom, and in the dosimetry studies, the data obtained from modeling against Experimental data There was a good agreement between the modeling results and the reference data. In the next step, a spherical tumor was considered in the Schneider head phantom, and considering that the purpose of this project is to investigate the effect of the magnetic field in reducing the dose of the sensitive organs near the tumor, a simple schematic of two of the sensitive organs in an oval shape was added around the tumor by Geant4 code. By applying a magnetic field with different sizes, we have examined the outputs in more detail. The results show that it is possible to produce a treatment plan with a pencil beam in the presence of a magnetic field and it meets the clinical limits for the target dose and risk areas. The chosen arrangement is a magnetic field perpendicular to the proton path, which causes the greatest deflection; Therefore, it can be concluded that there is no dosimetric barrier to provide tumor dose in concurrent imaging with proton therapy when MRI with T1 field strength (or lower) is used. In addition, for Specific tumors, according to the location of the side organs, it is possible to reduce the dose of the sensitive organs around the tumor by designing a suitable magnetic field. In this study, the dose of the organs at risk around the brain tumor was investigated and the benefits of proton dosimetry under the magnetic field in protecting the organs. Vitality of the body was observed
  9. Keywords:
  10. Brain Tumor ; Proton Therapy ; Beam Data Library ; Magnetic Field-Modulated Proton Therapy ; Geant4 Application for Tomographic (GATE)Emission ; Cancer Treatment

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