Measurement of linear accelerator spectra, reconstructed from percentage depth dose curves by neural networks.

Purpose Linear accelerator (linac) spectra, used to improve the accuracy of dose calculation and to produce a complete description of beam quality, among other aspects, are relevant in radiotherapy and linear accelerator physics. Methods In this work we apply neural networks in solving an ill-conditioned system of linear equations, to indirectly measure the linear accelerator spectra via the percentage depth dose curves. The photon beam spectra are related to radiation doses through a Fredholm integral equation.

A novel and fast methodology to calculate doses in LDR brachytherapy.

We present the concept of a new methodology for faster simulation of the doses in brachytherapy with permanent implants, based on the knowledge of the seeds arrangement, adding previously simulated doses in an equivalent medium in terms of the atomic composition of the organ in question. To perform the doses calculations we use Monte Carlo simulations. We simulated a cylindrical I-125 seed and compared our results against published data.

Influence of the sample density in γ spectrometry.

The determination of γ activities of radionuclides in the environment is of great interest and good accuracy is required in the results of these measurements. However, one of the main sources of error in this technology is the difference in the densities of the samples, because the effects of self-absorption, within the samples, become significant. We have produced Monte Carlo simulations for samples with different densities and for photons with energies in the range of interest, obtaining the peak efficiency as a function of density and energy.

A methodology to determine natural radioactivity by γ spectrometry without using calibrated standard samples.

When determining the radioactivity in materials by γ spectra, different processes are involved difficulting the fit. Besides, calibrated standard samples are necessary. In this work we propose a methodology to determine natural radioactivity using simulated γ spectra by Monte Carlo and without the use of calibrated standard samples.

Analysis of X-ray absorption spectra of the K and L2,3 edges of GaN within the FP-LAPW method.

Gallium nitride, GaN, is a semiconductor material with several technological applications. In this work we obtain ab initio XANES spectra using FP-LAPW method within the DFT formalism using different potentials (LDA, PBE and TB-mBJ) in order to study the electronic properties of the system. The spectra calculated using the effect of the fractional core hole were compared with experimental data obtaining a very good agreement.

L X-ray fluorescence cross sections experimentally determined for elements with 45 < Z < 50 at 9 keV.

Experimental determination of L fluorescence cross-sections for elements with 45 View Article and Find Full Text PDF