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[en] In IGRT of deformable head-and-neck anatomy, patient setup corrections are derived by rigid registration methods. In practice, experienced radiation therapists often correct the resulting vectors, thus indicating a different prioritization of alignment of local structures. Purpose of this study is to transfer the knowledge experts apply when correcting the automatically generated result (pre-match) to automated registration. Datasets of 25 head-and-neck-cancer patients with daily CBCTs and corresponding approved setup correction vectors were analyzed. Local similarity measures were evaluated to identify the criteria for human corrections with regard to alignment quality, analogous to the radiomics approach. Clustering of similarity improvement patterns is applied to reveal priorities in the alignment quality. The radiation therapists prioritized to align the spinal cord closest to the high-dose area. Both target volumes followed with second and third highest priority. The bony pre-match influenced the human correction along the crania-caudal axis. Based on the extracted priorities, a new rigid registration procedure is constructed which is capable of reproducing the corrections of experts. The proposed approach extracts knowledge of experts performing IGRT corrections to enable new rigid registration methods that are capable of mimicking human decisions. In the future, the deduction of knowledge-based corrections for different cohorts can be established automating such supervised learning approaches.
[en] The main postulates of the quantum electrodynamics of bilocal fields are formulated, the theory containing three universal constants, c, h, and k. The fermion-photon form factor is determined, and the new theory is used to calculate radiative corrections in first-order perturbation theory for the fine-structure constant, fermion mass and magnetic moment, Coulomb potential, and fermion and photon Green's functions. The value α = 1/137.0345 is obtained for the fine-structure constant
[en] We discuss a parity breaking in theories of fermions, which are trapped inside four-manifolds with boundaries. Even though these theories are parity-invariant at the classical level, the radiative corrections induce parity-violating boundary terms. The effect is present in both gauge and gravitational sectors. (author)
[en] We present an alternative technique for evaluating multiloop Feynman diagrams, using the integration by fractional expansion method. Here we consider generic diagrams that contain propagators with radiative corrections which topologically correspond to recursive constructions of bubble type diagrams. The main idea is to reduce these subgraphs, replacing them by their equivalent multiregion expansion. One of the main advantages of this integration technique is that it allows one to reduce massive cases with the same degree of difficulty as in the massless case.
[en] Weak and e.m. radiative corrections to vector boson masses are computed. Including corrections due to the presently known leptons and quarks, mass shifts of +3080 and +3310 MeV are obtained for the masses of the charged and neutral vector boson. (orig.)
[en] The calculation of the radiative corrections in γ-γ processes can be divided into two classes: - contributions from the interferences between the α4 order and the ''virtual'' corrections - ''real'' contributions from the emission of a real photon
[en] In this paper, we consider logarithmic radiative corrections and higher order terms to the supersymmetric hilltop F- and D-term hybrid inflation models. Conventional F- and D-term hybrid inflation only predicts ns∼>0.98. We show that via a positive quadratic and a negative quartic correction the spectral index can be reduced to ns = 0.96 suggested from latest WMAP result and also cosmic string problem appeared in SUSY hybrid inflation can be solved with mild tuning of the parameters if κ∼<0.01 for F-term inflation and g∼<0.05 for D-term inflation
[en] Radiative corrections to the electromagnetic field of a dyon due to vacuum fluctuations of the scalar charged particles are calculated in the one-loop approximation. It is shown that their contribution antishields the magnetic charge of the dyon and shields its electric charge. 14 refs