Abstract

WILCHES, Jorge H.; APAZA, Danny G.  and  COSTA, Alessandro M. Da. ON THE POSSIBILITY OF USE THE TIKHONOV REGULARIZATION METHOD TO RECONSTRUCT THE ENERGY SPECTRUM OF A CLINICAL ELECTRON BEAM. Momento [online]. 2020, n.60, pp.1-17.  Epub Mar 25, 2020. ISSN 0121-4470.  https://doi.org/10.15446/mo.n60.75527.

In radiotherapy, the electron energy spectrum is the most important characteristic for modelling the radiation source whose purpose is an accurate dose calculation. There are mainly three approaches to obtain the energy spectrum: (i) simulation of the source via Monte Carlo; (ii) direct measurement via a magnetic spectrometer and (iii) inverse reconstruction using an appropriate mathematical model. Among them, inverse reconstruction is considered the most appropriate for its simplicity, efficiency and speed despite not being the most accurate. Since inverse reconstruction is an ill-posed problem the Tikhonov regularization is used to overcome this problem and thereby obtain the spectrum. The reconstruction success is evaluated using the gamma index. Results show Tikhonov regularization is able of reconstructing the energy spectrum of a clinical electron beam within gamma index clinical acceptance criterion of > 95% within 1 %/1 mm.

Keywords : Contamination Photons; Fredholm; Gamma Index; PENELOPE.

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