Optimization of imaging parameters for Yttrium-90 bremsstrahlung emission computed tomography after selective internal radiotherapy
摘要
Yttrium-90 labeled microspheres based selective internal radiotherapy (90Y-SIRT) is an established local-regional therapy for unresectable hepatocellular carcinoma (HCC) which demonstrating significant survival improvements in multiple clinical trials. Post therapeutic 90Y imaging is essential for in vivo 90Y microspheres biodistribution evaluation and absorbed dose estimation. We aim to study the effects of 90Y bremsstrahlung imaging parameters including energy window center, width and acquisition time on the quality of 90Y SPECT/CT to provide optimal imaging conditions after 90Y-SIRT.
ResultsUsing the NEMA IEC NU2 body phantom and Siemens Symbia™ T16 SPECT/CT scanner equipped with a high-energy general-purpose collimator (HEGPC), seven energy window settings and two acquisition times (20s / frame and 40s / frame) were investigated and analyzed. 90Y bremsstrahlung imaging with 94 keV ± 40% energy window limits and 20s / frame acquisition time demonstrated the highest contrast-to-noise ratio (CNR) and contrast recovery coefficient (QH). In further analysis using a single hot sphere (diameter = 22 mm), the imaging parameter combination of 94 keV ± 40% and 20s / frame showed the lowest coefficient of variation (COV), while the residual count error in the lung insert (
For HEGPC, 94 keV ± 40% with 20s / frame is the optimal acquisition parameter for 90Y BECT imaging, while 80 keV ± 30% is also good energy window center and widths.