Energy window optimization for Y-90 Bremsstrahlung SPECT imaging: A Monte Carlo simulation study

Abstract

Introduction: In Y-90 imaging, image quality is highly dependent on choosing the energy window and collimator design because, the Y-90 bremsstrahlung photons have a continuous and broad energy distribution. The aim of this work was to optimize the bremsstrahlung energy window setting and collimator to improve both resolution and sensitivity. Materials and methods: We simulate the Siemens Medical System Symbia using the SIMulation of Imaging Nuclear Detectors (SIMIND) Monte Carlo program. The SIMIND was used to generate the Y-90 bremsstrahlung Single Photon Emission Computed Tomography (SPECT) projection of the point source. In order to assess the effect of the energy window on the resolution, six energy windows settings and two collimators denoted Medium Energy (ME) and High Energy (HE) were used. Results: The experimental measurement and simulation results exhibited a similar pattern in point spread functions (PSFs) with energy window. The simulation data show that, the geometric component reaches 73% for 51-120 keV energy window with HE collimator. In addition, the results showed that, the Full Width at Half Maximum (FWHM) and Full Width at Tenth Maximum (FWTM) (FWHM =7 mm + FWTM =35mm) was better in this window relative to other window. Conclusion: The optimal energy window for Y-90 bremsstrahlung SPECT imaging was 51- 120 keV. The obtained optimal energy window and optimal HE collimator has the potential to improve the image resolution and sensitivity of Y-90 SPECT images.