Monte Carlo modeling of gold nanoparticles detection limits of benchtop three‐dimensional L‐ and K‐shell X‐ray fluorescence mapping systems

Abstract

AbstractThis study aims to investigate the detection limits of gold nanoparticle (GNP) concentrations by Monte Carlo (MC) modeling of benchtop polychromatic K‐ and L‐shell X‐ray fluorescence mapping system. In Monte Carlo N‐Particle (MCNP version 6.1) simulations, a 0.25‐cm‐diameter cylinder containing GNPs of various concentrations (i.e., 0.005%–1.0% gold by weight, wt%) was assumed to be located at the center of a cylindrical water phantom of various diameters (1.0–10 cm). Two different sets of incident pencil beam X‐rays and detectors were modeled to stimulate X‐ray fluorescence (XRF) of GNPs: (1) 62 kVp and silicon drift detector for L‐XRF, (2) 105 kVp and cadmium telluride detector for K‐XRF. The detection limits were calculated for given radiation doses to the center of phantom (375–1500 mGy). When the diameter of the phantom was 1 cm, the detection limits for L‐XRF and K‐XRF were an order of 0.001 wt% and of 0.01 wt%, respectively. The detectability of K‐XRF turned out to be superior to that of L‐XRF for the phantoms greater than or equal to 3 cm in diameter. The MC results will provide a guide for developing an optimal benchtop XRF imaging system for in vivo preclinical imaging, depending on the sizes of GNP‐loaded objects, GNP concentrations, and radiation doses.