Investigating methods of normalization for X-ray fluorescence measurements of zinc in nail clippings using the TOPAS Monte Carlo code.

Development of portable X-ray fluorescence devices has made it easier to quickly assess trace elements such as zinc in human tissue. A TOPAS Monte Carlo code was used to investigate the use of a portable X-ray fluorescence system for detecting zinc in nail clippings. The obtained energy spectra from different nail thicknesses were analyzed and three different normalization techniques (coherent, Compton, and entire spectrum) were introduced.

Radiobiological impact of gadolinium neutron capture from proton therapy and alternative neutron sources using TOPAS-nBio.

Purpose: A multi-scale investigation of the biological properties of gadolinium neutron capture (GdNC) therapy with applications in particle therapy is conducted using the TOPAS Monte Carlo (MC) simulation code. The simulation results are used to quantify the amount of gadolinium dose enhancement produced as a result of the secondary neutron production from proton therapy scaled by measured data.

Materials And Methods: MC modeling was performed using the radiobiology extension TOol for PArticle Simulation TOPAS-nBio MC simulation code to study the radiobiological effects produced from GdNC on a segment of DNA, a spherical cellular model, and from the modeling of previous experimental measurements.

Neutron activation of gadolinium for ion therapy: a Monte Carlo study of charged particle beams.

This study investigates the photon production from thermal neutron capture in a gadolinium (Gd) infused tumor as a result of secondary neutrons from particle therapy. Gadolinium contrast agents used in MRI are distributed within the tumor volume and can act as neutron capture agents. As a result of particle therapy, secondary neutrons are produced and absorbed by Gd in the tumor providing potential enhanced localized dose in addition to a signature photon spectrum that can be used to produce an image of the Gd enriched tumor.

Investigating neutron activated contrast agent imaging for tumor localization in proton therapy: a feasibility study for proton neutron gamma-x detection (PNGXD).

Proton neutron gamma-x detection (PNGXD) is a novel imaging concept being investigated for tumor localization during proton therapy that uses secondary neutron interactions with a gadolinium contrast agent (GDCA) to produce characteristic photons within the 40-200 keV energy region. The purpose of this study is to experimentally investigate the feasibility of implementing this procedure by performing experimental measurements on a passive double scattering proton treatment unit. Five experimental measurements were performed with varying concentrations and irradiation conditions.

Collective Excitations in Protein as a Measure of Balance Between its Softness and Rigidity.

In this article, we elucidate the protein activity from the perspective of protein softness and flexibility by studying the collective phonon-like excitations in a globular protein, human serum albumin (HSA), and taking advantage of the state-of-the-art inelastic X-ray scattering (IXS) technique. Such excitations demonstrate that the protein becomes softer upon thermal denaturation due to disruption of weak noncovalent bonds. On the other hand, no significant change in the local excitations is detected in ligand- (drugs) bound HSA compared to the ligand-free HSA.