Simulation of high-performance cost-effective stationary cardiac DC-SPECT system with dynamic capability

107 Objectives Current state of the art cardiac SPECT systems (D-SPECT from Spectrum-Dynamics and Discovery NM530 from GE) use CZT semiconductor detectors which results in a number of cost-performance tradeoffs. Those systems are based on the use of large collimator holes (compared with collimators used in standard dual head gamma camera) to increase the system sensitivity that may result in poor image resolution when no resolution recovery applied. It is known that to provide an image of photon-starved organs, such as the heart, in a short period of time, there should be many simultaneously acquired projections (views of the heart). This translates to a large detector coverage that may result in unfavorable system development cost. Our goal is to develop a cost-effective stationary multi-pinhole SPECT platform with body-contouring geometry for cardiac applications that can provide high-resolution images (with no need of resolution recovery) with dynamic capability. Methods Our SPECT system is based on utilizing 30+ CsI:Tl detector modules each with their dedicated pinhole collimator acquiring an image of the heart. CsI:Tl detectors are pixelated into 2x2x10 mm3 pixel forms to provide high intrinsic detector resolution (IDR). The improved IDR helps reducing the magnification factor and thus allows for large number of detector modules placed in a body-contouring gantry. To reduce the detector fabrication cost, we utilize Laser-Induced Optical Barriers (LIOB) technique that is flexible, fast and cost-effective compared with the current fabrication methods which are cumbersome, expensive, and typically result in sub-optimal trade-off between key detector performance and cost metrics. With our current fabrication process that only uses single laser beam, we can fabricate 20x20x10 mm3 CsI:Tl crystals into 2 mm pixels about an hour. In this work, we report on the performance evaluation of our cardiac SPECT system, DC-SPECT, using GATE simulation environment. We used NEMA-NU-2001 standard and compared the expected performance of multiple designs of DC-SPECT with respect to the standard dual-head gamma camera as well as other cardiac SPECT systems. In one design, 70x70 mm2 detector modules are arranged in 3-4 rows where each row accommodates 12-15 modules. Each module has a single pinhole with 3 mm hole diameter. The system is designed in a curved configuration with a 225 degree arc of pixelated CsI:Tl detectors. The distance from the pinhole to center of the heart is 20 cm. Results The primary result shows that DC-SPECT can provide 0.082 system geometric efficiency (SGE) and system spatial resolution (SR) of 10.2 mm without resolution recovery at 20 cm distance from the FOV center. SGE and SR are 0.12 and 9.3 mm FWHM at 15 cm, respectively. This yields a ~10 times higher sensitivity compared with the dual-head camera which can be translated to lower dose, or larger patient throughput. Conclusions Simulation results show that DC-SPECT outperforms other SPECT systems in all performance metrics mainly due to the use of wide-angle collimators and large detector coverage, and the use of detectors with high IDR that enables many simultaneous projections of the heart. By utilizing cost-effective scintillator and pixelation technique, DC-SPECT development will be inexpensive compared with other mainstream cardiac SPECT systems that are based on CZT detectors.