Spectro-angular mapping of localized gold inclusions in Intralipid phantoms

We have applied an interstitial radiance-based technique based on a spectro-angular mapping approach to the identification and angular localization of 250-nm and 5-nm Au nanoparticle-based inclusions and non-scattering (water only) inclusions in the Intralipid-1% liquid phantom. A combination of the point radiance spectroscopy and white light spectroscopy was used to measure angular resolved light distribution in 450-900 nm spectral range in Intralipid-1% with and without localized inclusions. Characteristic spectro-angular snapshots of the liquid phantom alone and with the localized inclusions were obtained. For liquid phantoms without inclusions, the snapshots demonstrate wavelength dependent light distribution inside the turbid medium. For liquid phantoms with gold inclusions, the approach allows to isolate the spectroscopic signatures of the inclusions from the background, identify locations of the inclusions in the angular domain and show how a presence of water in the inclusion affects spectral identification and angular localization of the target. For liquid phantoms with water-based inclusions, an ability of the inclusion to enhance photon density above reference values and angular dependent signatures were demonstrated. The technique is seen as a potential tool in prostate treatment and diagnostics with gold nanoparticles.