Imaging assessment of photosensitizer emission induced by radionuclide-derived Cherenkov radiation using charge-coupled device optical imaging and long-pass filters

Figure 4 Detection of Cherenkov radiation and emission spectrum of tetrakis (4-carboxyphenyl) porphyrin induced by Cherenkov radiation. A: Bioluminescence imaging of prepared samples ⁶⁴CuCl₂ (4 mCi) and ⁶⁴CuCl₂ (4 mCi) + tetrakis (4-carboxyphenyl) porphyrin (TCPP) (30 μmol/L) with or without covering by long-pass filters (upper row), and TCPP fluorescence image after subtraction in differential image analysis (lower row); B: Similar images acquired from the experiment using ⁶⁴CuCl₂ (2 mCi); C: Similar images acquired from the experiment using ⁶⁴CuCl₂ (1 mCi); D: TCPP fluorescence spectrum calculated by subtracting the total flux of ⁶⁴CuCl₂ from that of ⁶⁴CuCl₂ + TCPP. The spectral peak was found in the 645–700 nm window. The peak is indicated by the red dotted circle. ⁶⁴Cu: ⁶⁴CuCl₂; PB: Phosphate buffer; μM: μmol/L.