Speaker
Description
Accurate quantification of Lu-177 uptake in radionuclide therapy requires precise calibration of SPECT/CT systems. This study aimed to determine calibration factors (CF) and recovery coefficients (RC) using Jaszczak and NEMA Image Quality phantoms under standardized acquisition and reconstruction protocols. Lu-177 SPECT/CT was performed with a dual-energy window protocol: main photopeak (208 keV ± 10%) and scatter correction windows (±5%). The Jaszczak phantom provided CF values, while the NEMA Image Quality phantom assessed RC across varying sphere-to-background concentration ratios. SPECT acquisition employed MELP collimators with 60 projections (10s/projection, 128x128 matrix, and zoom 1.0). Reconstruction utilized hybrid recon (5i, 16ss) with resolution recovery, scatter correction, and attenuation correction. The CF derived from the Jaszczak phantom was [10.6: 10.8 CPS/MBq]. RC varied significantly with sphere size, highlighting the dependence of quantification accuracy on spatial resolution. Scatter correction and resolution recovery were critical for improving RC for smaller spheres (<10 mm). This study establishes robust calibration and recovery protocols for Lu-177 SPECT/CT imaging, facilitating enhanced accuracy in dosimetry calculations. The use of optimized energy windows and advanced reconstruction algorithms significantly impacts quantification reliability. These findings strongly advocate for the standardization of Lu-177 imaging protocols, underscoring their crucial role in clinical applications.
