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  • 2025

    Bremsstrahlung, as an important radiation process in atomic physics, has significant applications in the fields of astrophysics, plasma physics, magnetic and inertial confinement fusion. In this work, the relativistic partial-wave expansion method is used to investigate the bremsstrahlung of neutral carbon atoms and different charged carbon ions scattered from intermediate- and high-energy relativistic electrons, with special attention paid to the electronic screening effect produced by the target electrons. The target wave function is obtained from the Dirac-Hartree-Fock self-consistent calculations, and the electron-atom scattering interaction potential is constructed in the central-field approximation. By solving the partial-wave Dirac equation, the continuum wave functions of the relativistic electron are obtained, from which the bremsstrahlung single and double differential cross sections can be calculated via the multipole free-free transitions between the incident and exit free electrons. The target electronic screening effects on the bremsstrahlung single and double differential cross sections are analyzed under a variety of conditions of incident electron energy and emitted photon energy. It is shown that the target electronic screening effect will significantly suppress the cross sections both at low incident energy and in the soft-photon region. Such a suppressing effect decreases with the incident electron energy and the emitted photon energy gradually increasing. Overall, the electronic screening effect has no significant influence on the shape function of bremsstrahlung.
    • Book : 74(3)
    • Pub. Date : 2025
    • Page : pp.033402-033402
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  • 2025

    Purpose Selecting the better techniques to harbor optimal motion management, either a stereotactic linear accelerator delivery using TrueBeam (TBX) or magnetic resonance–guided gated delivery using MRIdian (MRG), is time-consuming and costly. To address this challenge, we aimed to develop a decision-supporting algorithm based on a combination of deep learning-generated dose distributions and clinical data.Materials and Methods We retrospectively analyzed 65 patients with liver or pancreatic cancer who underwent both TBX and MRG simulations and planning process. We trained three-dimensional U-Net deep learning models to predict dose distributions and generated dose volume histograms (DVHs) for each system. We integrated predicted DVH metrics into a Bayesian network (BN) model incorporating clinical data.Results The MRG prediction model outperformed the TBX model, demonstrating statistically significant superiorities in predicting normalized dose to the planning target volume (PTV) and liver. We developed a final BN prediction model integrating the predictive DVH metrics with patient factors like age, PTV size, and tumor location. This BN model an area under the receiver operating characteristic curve index of 83.56%. The decision tree derived from the BN model showed that the tumor location (abutting vs. apart of PTV to hollow viscus organs) was the most important factor to determine TBX or MRG. It provided a potential framework for selecting the optimal radiation therapy (RT) system based on individual patient characteristics.Conclusion We demonstrated a decision-supporting algorithm for selecting optimal RT plans in upper gastrointestinal cancers, incorporating both deep learning-based dose prediction and BN-based treatment selection. This approach might streamline the decision-making process, saving resources and improving treatment outcomes for patients undergoing RT.
    • Book : 57(1)
    • Pub. Date : 2025
    • Page : pp.186-197
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