The objective of this work is to quantify the systematic errors introduced by the common assumption of invariant secondary electron spectra with changing field sizes, as relevant to stereotactic radiotherapy and other treatment modes incorporating small beam segments delivered with a linac-based stereotactic unit. The EGSnrc/BEAMnrc Monte Carlo radiation transport code was used to construct a d...

Bohr's centenary stopping-power formula is rederived for a free electron gas (FEG) system within the framework of nonrelativistic classical mechanics. A simple and more concise expression stopping power charged particles in FEG demonstrated on grounds. Using semiclassical arguments Euler-Maclaurin well-known mathematical formula, Bloch's correction that links Bethe's quantum theory to model als...

An accurate system matrix is required for quantitative proton CT (pCT) image reconstruction with iterative projection algorithms. The system matrix is composed of chord lengths of individual proton path intersections with reconstruction pixels. In previous work, reconstructions were performed assuming constant intersection chord lengths, which led to systematic errors of the reconstructed proto...

New analytical formulas for the electronic stopping power and the energy loss straggling of low velocity extended charge projectiles in the degenerate electron gas are calculated within the dielectric function method. The stopping and straggling effective charges Zeff of a projectile were analysed. They are found to differ one from the other and to depend on the electron gas density rs, on the ...

This paper presents a criterion for stopping non-linear iterative algorithms, specifically the Richardson-Lucy algorithm that is widely used to restore images from the Hubble Space Telescope. The criterion is based on generalized cross-validation and is also computed iteratively. We will present examples displaying the power of the stopping rule, and will discuss the abilities and shortcomings ...