Quantitative performance of a 3D CZT and conventional SPECT/CT for Tb-161 imaging

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Radiochemistry

Background:

• Terbium-161 (Tb-161) is a promising radionuclide for targeted radionuclide therapy.
• SPECT/CT imaging is crucial for dosimetry and treatment planning in targeted radionuclide therapy.
• Assessing imaging system performance is vital for accurate clinical application.

Purpose of the Study:

• To evaluate the imaging performance of a 3D Cadmium Zinc Telluride (CZT) SPECT/CT system for Tb-161.
• To compare the quantitative accuracy and image quality of 3D CZT SPECT/CT with a conventional Sodium Iodide [NaI(Tl)]-based SPECT/CT system for Tb-161.

Main Methods:

• A NEMA Image Quality (IQ) phantom was scanned using both a 3D CZT SPECT/CT and a conventional SPECT/CT system.
• Acquisition times were 8 minutes for the 3D CZT system and 16 minutes for the conventional system.
• Reconstruction protocols were optimized for Sphere-to-Background Ratio (SBR) and noise levels.

Main Results:

• The 3D CZT system achieved a 20% and 34% higher SBR with lower Coefficient of Variation (CoV) compared to the conventional system.
• Calibration factors differed significantly between the two systems (15.17 cps/MBq for conventional vs. 4.8 cps/MBq for 3D CZT).
• Reducing scan time on the 3D CZT system had minimal impact on SBR but increased noise with a twofold count reduction.

Conclusions:

• Both conventional and 3D CZT SPECT/CT systems can perform quantitative Tb-161 imaging.
• The 3D CZT system demonstrates higher sensitivity, leading to superior image quality and quantitative accuracy.
• The 3D CZT system is preferred due to its ability to achieve better results in half the acquisition time of conventional systems.