Author: Mohammadreza Ay, Nahal Daneshgar, Nima Kasraie, Abbas Monsef, Zeinab Peymani, Hadi Rezaei, Peyman Sheikhzadeh 👨🔬
Affiliation: University of Minnesota Medical School, Radiation Oncology, Department of Nuclear Medicine, Shariati Hospital, Tehran University of Medical Sciences, Shiraz University of Medical Sciences, Department of Medical Physics, Tehran University of Medical Sciences, Department of Medical Physics and Biomedical Engineering, UT Southwestern Medical Center, Imam Khomeini Hospital Complex,Tehran University of Medical Sciences 🌍
Purpose:
This study aims to design and simulate an innovative pediatric-dedicated SPECT scanner optimized for children’s unique anatomical and safety needs by enhancing sensitivity in data acquisition and minimizing radiation exposure.
Methods:
A Monte Carlo simulation model of a pediatric SPECT system was developed using the GATE (Geant4 Application for Tomographic Emission) toolkit. The detector head, collimator, and geometric configurations were meticulously modeled based on technical specifications and physical measurements using 99mTc as the source. The system was configured with four-head arrangements, each panel 19*30 cm² of NaI-based crystals followed encompassed by Low Energy High Resolution (LEHR) collimator. Comprehensive evaluations of the system were conducted using a variety of phantoms, including point source, line source, Derenzo phantom, NEMA phantom, and a pediatric body-sized XCAT phantom. The tests assessed the system’s performance metrics, including spatial resolution, energy spectrum, sensitivity, scan time, and optimal activity regimen as well as image quality. Results were benchmarked against those of conventional scanners.
Results:
A significantly higher peak sensitivity at the center of the FOV (332 cpm/µCi) was achieved compared to the traditional system's 166 cpm/µCi. Moreover, by reducing the number of required rotation steps, the proposed design can shorten scan time by 50% while maintaining comparable energy resolution (10% vs. 9% at 140 keV). However, it resulted in a broader radial resolution at the axial center (FWHM: 12 mm vs. 8 mm).
Conclusion:
The proposed SPECT configuration indicates an enhanced sensitivity in data acquisition and reduced radiation exposure. In the meantime, the current phase of project focuses on implementing algorithms to rectify the spatial resolution issues. This advancement could elevate significance of pediatric nuclear medicine such as epilepsy and oncology applications, while offering a safe and robust scan for children in clinical settings worldwide.