ESTRO 2023 - Abstract Book

S1562

Digital Posters

ESTRO 2023

Figure 1. Geometry of the simulated system: a) maximally simplified geometry consisting of an electron source and detectors placed in a water phantom (hereinafter referred to as simple); b) extended geometry with all elements of the accelerator head (hereinafter referred to as full), simplified drawing, no scale. Results Optimal regularization parameters determined based on similarity indicators for the spectrum and the dose distribution differ for geometry models considered in the study. The regularization parameter for the simple geometry ranged from 0.03 to 0.05, while for full geometry, they were from 0.05 to 0.06. The results for conventional linear accelerators found in the literature range from 0.5 to 1.1. Conclusion The Dual Annealing optimization method can be effectively used to solve the Fredholm equation with Tikhonov regularization to reconstruct an electron beam's energy spectrum. The regularization parameter value depends on the beam-forming system. Its value for the mobile accelerator considered in the study ranges from 0.05 to 0.06, depending on the nominal beam energy value (Figure 2).

Figure 2. An example of comparison of the reconstructed (orange) and reference (blue) spectrum for the geometry with all the elements of the machine (full geometry) for a nominal energy of 6 MeV for the three values of the regularization parameter λ . The lower charts show the difference.