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Modeling and Optimization of Respiratory-Gated Proton Therapy for Breast Cancer Using Monte Carlo Simulation

Piruzan, Elham | 2022

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 54828 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Vosoughi, Naser; Mahani, Hojjatollah
  7. Abstract:
  8. Breast cancer is the most common cancer among women and has a growing rate. A combination of the proton beam and Accelerated partial breast irradiation (APBI) strategy can be effective in the case of the respiratory-induced target motion for breast cancer treatment. Due to the proximity of breast tissue to the two critical organ at risks (OARs) such as the lungs and heart, breast cancer proton therapy requires special considerations. The use of proton therapy with respiratory considerations (respiratory-gated), although a powerful way to control the mobile targets in breast cancer proton therapy, but needs to be optimized and improved as much as efficiency.The simulation and modeling of the detailed passive scattering proton therapy system was developed. In this study, the integration of gating and proton therapy was implemented and then quantitative evaluation of tumor topology properties such as location, size and their effects on the outcomes of GATE simulations were investigated in respiratory gating breast cancer proton therapy. Next, the optimized treatment planning was provided for the left-sided breast cancer proton therapy.To do aim, a comprehensive passive scattering treatment proton therapy nozzle was modeled in the GATE platform. Next, a four-dimensional voxalized XCAT phantom was used to the modeling respiratory-induced motion and to produce 4DCT images. XCAT phantom also allows very high resolution dosimetry calculations (voxel dimensions). In addition, all the mentioned simulations and optimizations were repeated for different proton radiation fields, the three tumor sites (deep medial (DM), deep lateral (DL) and shallow) and as well as with different patient positions. Finally, the optimal conditions for the mentioned modes were compared. Dose volume histogram (DVH) curves were illustrated. Also, in order to determine the optimal parameters of the treatment planning, weighted sum method was used as a standard and powerful optimization method.Due to the greater range of motion of PTV in the Supine position, compared to Prone, and based on the SF values calculated for different OARs, the effectiveness of the gating method in the Supine position was greater than that of the Prone. Treatment plan evaluation parameters for maximum, minimum and median values were extracted by DVH curves that include V100%(PTV): 100%, 94%, 97%; V95%(PTV): 100%, 99.80%, 100%; V50%(non-target breast): 26%, 7.5%, 15%; V50% (skin): 30%, 9%, 18%; V5%(lung): 8%, 0, 5%; V5%(heart); 5%, 0, 3% respectively. The optimal DF values for DL, DM and Shallow tumor sites were 25%, 20% and 25%, respectively.GATE platform is more efficient for the optimal modeling of the proton therapy system. The findings demonstrate that beam gating is efficient for left-sided breast cancer proton therapy. The treatment phases of 5, 4 and 4 are optimum for DM, DL and shallow tumor sites respectively for the left-sided breast cancer proton therapy. Also, sparing the non-target breast tissue is superior arising from implementing the gating technique.
  9. Keywords:
  10. Optimization ; Breast Cancer ; Proton Therapy ; Monte Carlo Method ; Geant4 Application for Tomographic (GATE)Emission ; Four-Dimensional Extended Cardiac-Torso (XCAT) Phantom

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