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A Mathematical Model to Consider Uncertainty in IMRT Treatment Planning

Amini Zadeh Zare, Monireh | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51865 (01)
  4. University: Sharif University of Technology
  5. Department: Industrial Engineering
  6. Advisor(s): Najafi, Mehdi
  7. Abstract:
  8. Intensity Modulated Radiation Therapy is one of the common methods for treating cancer patients because of the ability to transfer high doses of radiation to the tumor and minimize damage to surrounding healthy organs. In this method, the patient is placed in a special bed, while a linear accelerator directs the beams to radiation to the target's size. Patient treatment requires a unique treatment plan, and optimization of the treatment plan involves two basic decisions: (1) selecting the beam angles; (2) calculating the beams intensity. In the radiation therapy process, there are various uncertainty factors, such as patient setup, tumor volume definition, tumor growth or movement, and the method of calculating the absorbed dose, which leads to changes in the treatment process and the treatment result error. In this research, the uncertainty of the Prescription dose and dose absorption Coefficient is considered. The uncertainty of these two parameters is considered in the model with the help of fuzzy theory and the fuzzy mixed integer programming model of this research has been developed. Then, using fuzzy number rankings, the fuzzy model has become the definitive model. One of the most widely used methods for solving the mixed integer programming model in radiotherapy literature is branching and pruning algorithm, which has been selected as a solution method and discussed in chapter four. The case study is a liver cancer. The liver is one of the largest organs in the human body that has several functions such as removing toxins from the body and it is essential to survive. Using the model of this study helps physicians instead of giving a dose for each dose of the toxoid, they will prescribe three fuzzy numbers for the entire target volume. Considering the fuzzy model, it is a tool available to physicians to determine the best strategy for patient's treatment according to the degree of membership (degree of certainty) in the prescribed dose and the actual dose rate, depending on the patient's physical condition even after the initial sessions Radiation therapy
  9. Keywords:
  10. Intensity Modulated Radiation Therapy (IMRT) ; Beam Angle Optimization ; Fluence Map Optimization ; Radiotherapy ; Treatment Planning ; Uncertainty

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