Neutron stimulated emission computed tomography for brain cancer imaging

Neutron stimulated emission computed tomography (NSECT) uses photons emitted from inelastic scattering of neutrons with biological objects to quantify the elemental composition of the object and reconstruct an image. Previously, NSECT has been used to detect liver and breast disease in vivo. In this study, we investigated the capability of imaging brain tumors using NSECT. A GEANT4 simulation was developed to model the brain, skull, and a spherical lesion. Images corresponding to phosphorus, sulfur, and iron (both individually and as combinations) were generated from a simulated NSECT scan. Signal-to-noise ratio (SNR) and full width at half maximum (FWHM) in the tumor region were calculated to assess image accuracy (FWHM ≤ 5% error) and detectability (SNR > 2.5). The scan with the least amount of absorbed dose required to achieve these criteria was defined as the optimal acquisition. The lowest dose value was found to be 0.0837 cGy for a 2 cm brain tumor imaged using a single germanium detector, 6 equally spaced angles from 0 to 180 degrees, 20 projections per angle and 0.5 million neutrons per projection. The SNR for the combination of phosphorus, sulfur, and iron with the given condition was 9.288 and FWHM for the iron was 15 mm with the given condition. In conclusion, NSECT is capable of imaging a 2 cm brain tumor using the elemental composition of phosphorus, sulfur, and iron with reasonable SNR, FWHM and radiation dose.