Zhang Jun, Maniawski Piotr, Knopp Michael V
Wright Center of Innovation in Biomedical Imaging, Department of Radiology, The Ohio State University Wexner Medical Center, 395 W. 12th Avenue, Room 430, Columbus, OH, 43210, USA.
Philips Healthcare, Cleveland, OH, USA.
EJNMMI Res. 2018 Nov 6;8(1):97. doi: 10.1186/s13550-018-0448-7.
The first solid-state silicon photomultiplier (SiPM) digital photon counting (DPC) clinical PET/CT system was introduced by Philips in recent years. The system differs from other SiPM-based PET/CT systems and uses lutetiumyttrium oxyorthosilicate (LYSO) scintillators directly coupled with their own individual SiPM DPC detectors eliminating the need for Anger-logic positioning decoding. We evaluated the system performance, characteristics, and stability of the next generation DPC clinical PET/CT based on NEMA NU2-2012 tests, NEMA NU2-2018 test (timing resolution) and human studies.
An energy resolution of 11.2% was measured. NEMA NU2-2012 tests revealed a spatial resolution (mm in FWHM) from (3.96, 4.01, 4.01) at 1 cm to (5.81, 5.83, 4.95) at 20 cm for (axial, radial, tangential). A 5.7 cps/kBq system sensitivity was measured. Peak noise equivalent count rate (NECR) and peak true count rate could not be determined as each exhibited increasing values up to the maximum activity measured (~ 1100 MBq). The maximum NECR was 171 kcps @ 50.5 kBq/mL, with corresponding scatter fraction of 30.8% and maximum trues of 681 kcps. NEMA hot sphere contrast ranged from 62% (10 mm) to 88% (22 mm), cold sphere contrast of 86% (28 mm) and 89% (37 mm). A timing resolution of 322 ps (Na point source based) and 332 ps (NEMA NU2-2018) was obtained. It revealed < 1% change in TOF timing and ± 0.4% change in energy resolution during 31-month stability monitoring. CQIE assessment found < 3% axial variance in SUV. 100-60% recovery coefficients of activity concentration at various sphere sizes and contrast levels were measured.
This scanner represents the first solid-state DPC PET/CT, a technologic leap beyond photomultipliers tubes and anger logic. It presents considerable improvements in system performance and characteristics with excellent time-of-flight capability compared to conventional photomultiplier tube (PMT) PET/CT systems. The DPC system leads to promising clinical opportunities with excellent image quality, lesion detectability, and diagnostic confidence.
近年来，飞利浦推出了首款基于固态硅光电倍增管（SiPM）的数字光子计数（DPC）临床PET/CT系统。该系统与其他基于SiPM的PET/CT系统不同，它使用直接耦合其各自独立SiPM DPC探测器的硅酸镥钇（LYSO）闪烁体，无需安杰逻辑定位解码。我们基于NEMA NU2 - 2012测试、NEMA NU2 - 2018测试（时间分辨率）和人体研究，评估了下一代DPC临床PET/CT的系统性能、特性和稳定性。
测得能量分辨率为11.2%。NEMA NU2 - 2012测试显示，轴向、径向、切向的空间分辨率（半高宽，单位为mm）在1 cm处为（3.96, 4.01, 4.01），在20 cm处为（5.81, 5.83, 4.95）。测得系统灵敏度为5.7 cps/kBq。由于在测量的最大活度（约1100 MBq）之前，峰值噪声等效计数率（NECR）和峰值真计数率均呈现不断增加的值，因此无法确定其峰值。最大NECR为171 kcps @ 50.5 kBq/mL，相应的散射分数为30.8%，最大真计数为681 kcps。NEMA热球对比度范围为62%（10 mm）至88%（22 mm），冷球对比度为86%（28 mm）和89%（37 mm）。获得了基于钠点源的时间分辨率为322 ps和基于NEMA NU2 - 2018的时间分辨率为332 ps。在31个月的稳定性监测期间，TOF时间变化小于1%，能量分辨率变化±0.4%。CQIE评估发现SUV的轴向方差小于3%。测量了不同球体尺寸和对比度水平下活性浓度的100 - 60%恢复系数。
该扫描仪代表了首款固态DPC PET/CT，是超越光电倍增管和安杰逻辑的技术飞跃。与传统光电倍增管（PMT）PET/CT系统相比，它在系统性能和特性方面有显著改进，具有出色的飞行时间能力。DPC系统凭借出色的图像质量、病变可检测性和诊断置信度带来了广阔的临床应用前景。
