基于LYSO的PET/CT系统在2D和3D采集模式下的NEMA NU 2-2001性能测量
NEMA NU 2-2001 performance measurements of an LYSO-based PET/CT system in 2D and 3D acquisition modes.
作者信息
Kemp Brad J, Kim Chang, Williams John J, Ganin Alexander, Lowe Val J
机构信息
Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA.
出版信息
J Nucl Med. 2006 Dec;47(12):1960-7.
UNLABELLED
The National Electrical Manufacturers Association (NEMA) NU 2-2001 performance measurements were conducted on the Discovery RX, a whole-body PET/CT system under development by GE Healthcare. The PET scanner uses 4.2 x 6.3 x 30 mm lutetium yttrium orthosilicate (LYSO) crystals grouped in 9 x 6 blocks. There are 24 rings with 630 crystals per ring and the ring diameter is 88.6 cm. The transaxial and axial fields of view are 70.0 and 15.7 cm, respectively. The scanner has retractable septa and can operate in both 2-dimensional (2D) and 3-dimensional (3D) modes. 2D acquisitions use ring differences of +/-4 for direct and +/-5 for cross slices; 3D acquisitions use a ring difference of 23. The coincident window width is 6.5 ns and the energy window is 425-650 keV. Other than the detectors, the system uses the same hardware and software as a Discovery ST. The CT scanner is a 16-slice LightSpeed; the performance characteristics of the CT component are not included herein.
METHODS
Performance measurements of sensitivity, spatial resolution, image quality, scatter fraction and counting rate performance, and image quality were obtained using NEMA methodology.
RESULTS
The system sensitivity in 2D and 3D was measured as 1.7 cps/kBq and 7.3 cps/kBq, respectively. The transaxial resolution for 2D (3D) was 5.1 mm full width at half maximum (FWHM) (5.0 mm) at 1 cm from gantry center and the radial and tangential resolutions were 5.9 mm (5.9 mm) and 5.1 mm (5.2 mm) at 10 cm, respectively. The axial resolution for 2D (3D) was 4.8 mm FWHM (5.8 mm) and 6.3 mm (6.5 mm) at 1 cm and 10 cm from gantry center, respectively. The scatter fraction was 13.1% and 31.8% in 2D and 3D. The peak noise equivalent count rate (NECR) was 155 kcps at 92.1 kBq/mL in 2D and 117.7 kcps at 21.7 kBq/mL in 3D for a noise-free estimation of randoms. The contrast of the 22, 17, 13, and 10 mm hot spheres in the image quality phantom in 2D (3D) were 74.6% (72.4%), 56.7% (59.5%), 46.2% (44.6%), and 17.9% (18.0%), respectively.
CONCLUSION
The Discovery RX is a scanner that possesses high NECR, low scatter fraction, and good spatial resolution characteristics.
未标注
对通用电气医疗集团正在研发的全身PET/CT系统Discovery RX进行了美国国家电气制造商协会（NEMA）NU 2 - 2001性能测量。PET扫描仪使用4.2×6.3×30毫米的正硅酸镥钇（LYSO）晶体，这些晶体被分组为9×6块。有24个环，每个环有630个晶体，环直径为88.6厘米。横向视野和轴向视野分别为70.0厘米和15.7厘米。该扫描仪有可伸缩隔板，可在二维（2D）和三维（3D）模式下运行。二维采集时，直接切片的环差为+/-4，交叉切片的环差为+/-5；三维采集时，环差为23。符合窗宽为6.5纳秒，能量窗为425 - 650千电子伏特。除探测器外，该系统使用与Discovery ST相同的硬件和软件。CT扫描仪是16层的LightSpeed；本文未包括CT组件的性能特征。
方法
使用NEMA方法获得了灵敏度、空间分辨率、图像质量、散射分数和计数率性能以及图像质量的性能测量结果。
结果
二维和三维系统灵敏度分别测量为1.7 cps/kBq和7.3 cps/kBq。在距机架中心1厘米处，二维（三维）横向分辨率在半高宽（FWHM）处为5.1毫米（5.0毫米），在10厘米处径向和切向分辨率分别为5.9毫米（5.9毫米）和5.1毫米（5.2毫米）。在距机架中心1厘米和10厘米处，二维（三维）轴向分辨率在FWHM处分别为4.8毫米（5.8毫米）和6.3毫米（6.5毫米）。二维和三维散射分数分别为13.1%和31.8%。对于无噪声随机估计，二维在92.1 kBq/mL时峰值噪声等效计数率（NECR）为155 kcps，三维在21.7 kBq/mL时为117.7 kcps。二维（三维）图像质量体模中22毫米、17毫米、13毫米和10毫米热球的对比度分别为74.6%（72.4%）、56.7%（59.5%）、46.2%（44.6%）和17.9%（18.0%）。
结论
Discovery RX是一款具有高NECR、低散射分数和良好空间分辨率特征的扫描仪。
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