Photon counting micro-CT imaging of Bi2WO6 nanoparticles

Photon Counting Detectors (PCD) have emerged as a transformative technology in CT and micro-CT imaging, offering enhanced contrast resolution and quantitative material separation in a single scan, a notable advancement from traditional energy-integrating detectors. The unique properties of bismuth tungstate (Bi₂WO₆) nanoparticles (NPs), hold promise in many applications, including contrast-enhanced CT imaging and photothermal therapy, especially in addressing tumor hypoxia challenges. However, despite these promising traits, the performance of PCCT imaging using Bi₂WO₆ NPs has not been fully explored. Our study bridges this gap by employing both simulations and real experiments. Using iterative PCCT reconstruction, we achieved significant noise reduction, from a noise standard deviation up to 786 Hounsfield Units (HU) down to 54 HU, enabling material decomposition. The dual K-edge of Bi2WO6, coupled with a precise 2:1 Bismuth to Tungsten ratio, offers a unique, quantifiable signature for PCCT imaging: the enhancement of Bi₂WO₆ remains largely constant over the diagnostic x-ray range (stddev: 1.24 HU/mg/mL over 25-91 keV energy thresholds, 125 kVp spectrum; iodine stddev: 11.62 HU/mg/mL). Improved separation of contrast material from intrinsic tissues promises to enhance all facets of clinical CT, including new avenues for radiation dose and metal artifact reduction. Potential new clinical applications include targeted radiation therapy, where Bi₂WO₆ NPs could intensify treatment efficacy and optimize chemotherapeutic delivery.