Radiation dose estimation in pencil beam x-ray luminescence computed tomography imaging

TL;DR

This study estimates radiation dose in pencil beam x-ray luminescence computed tomography (XLCT) imaging using Monte Carlo simulations, showing potential dose reduction with advanced x-ray sources for small animal molecular imaging.

Contribution

It provides the first dose estimation for pencil beam XLCT imaging using Monte Carlo simulations and evaluates the impact of different x-ray sources on dose levels.

Findings

Dose to bone marrow estimated at 30 mGy with advanced x-ray source.

High-brilliance, quasi-monochromatic sources can reduce radiation dose.

Monte Carlo simulations effectively model dose distribution in XLCT.

Abstract

Pencil x-ray beam imaging provides superior spatial resolution than other imaging geometries like sheet beam and cone beam geometries due to the illumination of a line instead of an area or volume. However, the pencil beam geometry suffers from long scan times and concerns over dose discourage laboratory use of pencil beam x-ray sources. Molecular imaging techniques like XLCT imaging benefit most from pencil beam imaging to accurately localize the distribution of contrast agents embedded in a small animal object. To investigate the dose deposited by pencil beam x-ray imaging in XLCT, dose estimations from one angular projection scan by three different x-ray source energies were performed on a small animal object composed of water, bone, and blood with a Monte Carlo simulation platform, GATE (Geant4 Application for Tomographic Emission). Our results indicate that, with an adequate x-ray benchtop source with high brilliance and quasi-monochromatic properties like the Sigray source, the dose concerns can be reduced. With the Sigray source, the bone marrow was estimated to have a radiation dose of 30 mGy for a typical XLCT imaging, in which we have 6 angular projections, 100 micrometer scan step size, and 10^6 x-ray photons per linear scan.