Sensitivity study of x-ray luminescence computed tomography.

X-ray luminescence computed tomography (XLCT) is a hybrid molecular imaging modality that combines the merits of both x-ray imaging (high resolution) and optical imaging (high sensitivity). In this study, we have evaluated the sensitivity of XLCT with phantom experiments by scanning targets of different phosphor concentrations at different depths. We found that XLCT is capable of imaging targets of very low concentrations (27.6 μM or 0.01 mg/mL) at significant depths, such as 21 mm. Our results demonstrate that there is little variation in the reconstructed target size with a maximum target size error of 4.35% for different imaging depths for XLCT. We have, we believe for the first time, compared the sensitivity of XLCT with that of traditional computed tomography (CT) for phosphor targets. We found that XLCT's use of x-ray-induced photons provides much higher measurement sensitivity and contrast compared to CT, which provides image contrast solely based on x-ray attenuation.