Design and optimization of a breast-dedicated SPECT scanner with multi-lofthole collimation

Abstract

Background: the need for simultaneous high-sensitivity and high-resolution breast SPECT imaging mandates to design and optimize dedicated scanners. Therefore, this work aims to design and optimize a novel breast-dedicated SPECT system with multi-lofthole collimator. Materials and Methods: in this research, a novel breast-dedicated scanner is designed and then optimized. The scanner is equipped with a single full-ring multi-lofthole collimation long with modular NaI(Tl) detectors. The step-and-shoot data acquisition was considered with two steps. Then, an analytic optimization was conducted to balance the existing sensitivity-resolution tradeoff. To do so, several scanner geometries were investigated. The optimal configuration maximized the system sensitivity at a given system resolution. Furthermore, the scanner was also modeled within the GATE simulator. Then, detector energy resolution, septal penetration and scattering, and system sensitivity were calculated. Analytic findings were also compared with the simulated ones. Results: the results showed that high sensitivity of about 2 cps/kBq can be obtained for a diameter of lofthole 3.05 mm with a 75° opening angle. Results of GATE simulations showed clinically acceptable performance of the system offering 9% energy resolution for a point source. The septal penetration and scattering were approximately 0.5% and 0.2%, respectively, for cylindrical water phantom and tungsten as collimator material. Conclusion: the designed SPECT scanner provides promising results in terms of sensitivity and spatial resolution and therefore outperforms the traditional multi-pinhole collimation by a much higher sensitivity at a given system resolution.

Performance Assessment of a Channel Multi-pinhole Collimator for Myocardial Perfusion Imaging with SPECT: A Monte Carlo Simulation

“…Among many components constituting a SPECT camera, the collimator plays a pivotal role and mainly affects the quality. This is because it controls the resolution, noise, and sensitivity of the final functional image [5]. While parallel-hole collimation is routinely used for cardiac SPECT imaging, there is no clinically-demanded resolution-sensitivity balance for simultaneously high-resolution and high-sensitivity imaging [6].…”

“…Because of its excellent spatial resolution, the pinhole collimator is used to image small animals, small organs, and small regions of interest, such as the thyroid and heart [7][8]. The multi-pinhole collimator was introduced as an alternative to single-pinhole collimators to increase sensitivity while maintaining spatial resolution [5]. A multi-pinhole collimator has several pinhole apertures in which increasing the number of holes improves the sensitivity [7].…”

“…Monte Carlo (MC) simulation plays a key role in the design and optimization of medical imaging systems, especially in computed tomography (CT), SPECT, and positron emission tomography (PET) [4,9]. Various MC toolkits such as GEANT4, MCNP/MCNPX, and GATE have been used for simulations of this type, each with a variety of capabilities [5]. The GATE simulator is based on the GEANT4 toolkit and is dedicated to medical physics applications like diagnostic imaging, nuclear medicine imaging/dosimetry, brachytherapy, and radiation therapy [10][11].…”