Resumen

WILCHES-VISBAL, J. H.  y  NICOLUCCI, P.. Improved reconstruction methodology of clinical electron energy spectra based on Tikhonov regularization and generalized simulated annealing. J. appl. res. technol [online]. 2021, vol.19, n.6, pp.622-632.  Epub 22-Mar-2022. ISSN 2448-6736.  https://doi.org/10.22201/icat.24486736e.2021.19.6.1213.

Electron beam radiotherapy is the most widespread treatment modality to deal with superficial cancers. In electron radiotherapy, the energy spectrum is important for electron beam modelling and accurate dose calculation. Since the percentage depth-dose (PDD) is a function of the beam’s energy, the reconstruction of the spectrum from the depth-dose curve represents an inverse problem. Thus, the energy spectrum can be related to the depth-dose by means of an appropriate mathematical model as the Fredholm equation of the first kind. Since the Fredholm equation of the first kind is ill-posed, some regularization method must be used to achieve a useful solution. In this work the Tikhonov regularization function was solved by the generalized simulated annealing optimization method. The accuracy of the reconstruction was verified by the gamma index passing rate criterion applied to the simulated PDD curves for the reconstructed spectra compared to experimental PDD curves. Results show a good coincidence between the experimental and simulated depth-dose curves according to the gamma passing rate better than 95% for 1% dose difference (DD)/1 mm distance to agreement (DTA) criteria. Moreover, the results show improvement from previous works not only in accuracy but also in calculation time. In general, the proposed method can help in the accuracy of dosimetry procedures, treatment planning and quality control in radiotherapy.

Palabras llave : Generalized Simulated annealing; Tikhonov regularization; depth-dose curve; gamma passing rate; dose profile; Monte Carlo.

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