Accuracy of a whole-body single-photon emission computed tomography with a thallium-bromide detector: Verification...

Single-photon emission computed tomography (SPECT) devices equipped with cadmium-zinc-telluride (CZT) detectors achieve high contrast resolution because of their enhanced energy resolution. Recently, thallium bromide (TlBr) has gained attention as a detector material because of its high atomic number and density.

This study evaluated the clinical applicability of a SPECT system equipped with TlBr detectors using Monte Carlo simulations, focusing on 99mTc and 177Lu imaging.

This study used the Simulation of Imaging Nuclear Detectors Monte Carlo program to compare the imaging characteristics between a whole-body SPECT system equipped with TlBr (T-SPECT) and a system equipped with CZT detectors (C-SPECT). The simulations were performed using a three-dimensional brain phantom and a National Electrical Manufacturers Association body phantom to evaluate 99mTc and 177Lu imaging. The simulation parameters were accurately set by comparing them with the actual measurements.

The T-SPECT system demonstrated improved energy resolution and higher detection efficiency than the C-SPECT system. In 99mTc imaging, T-SPECT demonstrated 1.71 times higher photopeak counts and improved contrast resolution. T-SPECT exhibited a significantly lower impact of hole tailing and higher-energy resolution (4.50% for T-SPECT vs. 7.34% for C-SPECT). Furthermore, T-SPECT showed higher peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) values, indicating better image quality. In 177Lu imaging, T-SPECT showed 2.76 times higher photopeak counts and improved energy resolution (3.94% for T-SPECT vs. 5.20% for C-SPECT). T-SPECT demonstrated a higher contrast recovery coefficient (CRC) and contrast-to-noise ratio (CNR) across all acquisition times, maintaining sufficient counts even with shorter acquisition times. Moreover, T-SPECT acquired higher low-frequency values in power spectrum density (PSD), indicating more accurate internal image reproduction.

T-SPECT offers superior energy resolution and detection efficiency than C-SPECT. Moreover, T-SPECT can provide higher contrast resolution and sensitivity in clinical imaging with 99mTc and 177Lu. Furthermore, the Monte Carlo simulations are confirmed to be a valuable guide for the development of T-SPECT.