Quantification of Gd-Nanoparticles Concentration with SPECT and Spectral Photon Counting CT

Gadolinium nanoparticles (NP) combined with conventional radiotherapy could be used for oncology treatment.Indeed, NPs concentrated in a tumor could enhance its radiosensitization. The noninvasive quantification of NP concentration is a crucial task for radiotherapy treatment planning as this will determine the delivered dose. Image based quantification could be achieved, for example, with spectral photon counting CT (SPCCT) for Gd detection or single photon emission CT (SPECT) for detection of NPs coupled with In-[111] tracer. This work is focused on Gd-NP quantification on phantoms with nanoSPECT/CT and SPCCT scanners. Somepreliminary in vivo results are also presented.