A feasibility evaluation of x-ray fluorescence emission tomography and x-ray luminescence tomography for real-time assessment of photodynamic therapy

Photodynamic Therapy (PDT) has found use in a wide-array of clinical applications such as in cancer and acne treatment. Photodynamic therapy, uses a photosensitive compound activated by a specific wavelength photon to produce cytotoxic oxygen species (either in free radical form or in singlet form). However, weak penetration of visible, infrared, and UV light into the body to activate the photosensitive compound significantly limits the use of PDT in cancer treatment. Additionally, PDT current lacks an effective dosimetry technique or means of quantifying the number of activated photosensitizers for investigative studies has proven difficult as well. Many researchers have delved into investigating x-ray induced PDT, which in combination of x-ray fluorescence computed tomography (XFCT), can produce a quantifiable therapeutic effect at greater bodily depths. This work demonstrates a novel combinatorial system of X-ray Fluorescence and X-ray Luminescence Computed Tomography (XLCT) to image LaF3 and Y2O3 nanoparticles. A 3D XFCT/CT image of a mouse phantom conjugated with a NMR tube containing bromide and Y2O3 was produced. Additionally, a cross sectional imaging in XFCT/XLCT/CT of a mouse phantom with microcapillaries filled with LaF3:Tb3+ and Y2O3:Eu3+ attached. The results demonstrated the plausibility of using a XFCT/XLCT/CT setup for monitoring therapeutic nanoparticles, but acquisition time and penetration depth issues will need to be addressed first