Performance evaluation of the new whole-body PET/CT scanner: Discovery ST
Performance evaluation of the new whole-body PET/CT scanner: Discovery ST
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DOI：
10.1007/s00259-003-1444-2
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发表时间：
2004-06-01
影响因子：
9.1
通讯作者：
Fazio, F
中科院分区：
文献类型：
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作者：
Bettinardi, V;Danna, M;Fazio, F
新集成 PET/CT 系统 Discovery ST（GE 医疗系统）的物理性能表征是按照 NEMA NU 2-1994 (N-94) 和 NEMA NU 2-2001 (N-01) 标准在 2D 和 3D 采集配置中进行的。 Discovery ST 将四层或八层多层螺旋 CT 扫描仪与 PET 断层扫描仪相结合，该断层扫描仪由排列成 24 个环的 10,080 个 BGO 晶体组成。晶体尺寸为 6.3x6.3x30 mm(3)，并以 6x6 晶体块的形式组织，耦合到具有四个阳极的单个光电倍增管。 PET 系统的 24 个环可获取 47 个图像，图像间隔为 3.27 毫米，覆盖轴向视野为 157 毫米。低能阈值和高能阈值分别设置为 375 keV 和 650 keV。重合时间窗口设置为 11.7 ns。采用NEMA N-94标准，主要结果为：（1）离轴1、10和20 cm处的平均（径向和切向）横向空间分辨率（FWHM）在2D中分别为6.28 mm、7.09 mm和7.45 mm，在3D中分别为6.68 mm、7.72 mm和8.13 mm； (2) 真实事件的灵敏度在 2D 中为 8,567 cps/kBq/cc，在 3D 中为 36,649 cps/kBq/cc； (3) 2D 中的散射分数为 15%，3D 中的散射分数为 30%； (4) 峰值真实事件率、系统死区时间 50% 时的真实事件率以及等于随机事件率时的真实事件率在 2D 中分别为 750 kcps (189.81 kBq/cc)、744 kcps (186.48 kBq/cc) 和 686 kcps (150.59 kBq/cc)，以及 922 kcps (2D)。 44.03 kBq/cc, 834 3D 中 53.28 kBq/cc 处的 kcps 和 44.03 kBq/cc 处的 921 kcps； (5) 3D 中的噪声等效计数 (NEC) 峰值速率为 270 kcps，为 34.38 kBq/cc，通过延迟事件估计随机巧合。使用NEMA N-01标准，主要结果为：（1）离轴1 cm和10 cm处的平均横向和轴向空间分辨率（FWHM）在2D中为6.28（4.56）mm和6.88（6.11）mm，在3D中为6.29（5.68）mm和6.82（6.05）mm； (2) 两个径向位置（r=0 cm 和 r=10 cm）的平均灵敏度在 2D 中为 1.93 cps/kBq，在 3D 中为 9.12 cps/kBq； (3) 2D 中的散射分数为 19%，3D 中的散射分数为 45%； (4) 当使用 NEC 公式中的 k=2 估计随机重合时，NEC 峰值速率在 2D 46.99 kBq/cc 处为 54 kcps，在 3D 10.84 kBq/cc 处为 45.5 kcps，而 NEC 峰值速率在 64.43 kBq/cc 处为 81 kcps，在 14.86 kBq/cc 处为 66 kcps 2D 和 3D 中的 kBq/cc， 分别是当使用 NEC 公式中的 k=1 估计随机巧合时。新型集成 PET-CT 系统 Discovery ST 在 2D 和 3D 方面均具有良好的整体性能，特别是高灵敏度和非常好的 3D NEC 响应。
Characterisation of the physical performance of the new integrated PET/CT system Discovery ST (GE Medical Systems) has been performed following the NEMA NU 2-1994 (N-94) and the NEMA NU 2-2001 (N-01) standards in both 2D and 3D acquisition configuration. The Discovery ST combines a four or eight multi-slice helical CT scanner with a PET tomograph which consists of 10,080 BGO crystals arranged in 24 rings. The crystal dimensions are 6.3x6.3x30 mm(3) and they are organised in blocks of 6x6 crystals, coupled to a single photomultiplier tube with four anodes. The 24 rings of the PET system allow 47 images to be obtained, spaced by 3.27 mm, and covering an axial field of view of 157 mm. The low- and high-energy thresholds are set to 375 and 650 keV, respectively. The coincidence time window is set to 11.7 ns. Using the NEMA N-94 standard, the main results were: (1) the average (radial and tangential) transverse spatial resolution (FWHM) at 1, 10 and 20 cm off axis was 6.28 mm, 7.09 mm and 7.45 mm in 2D, and 6.68 mm, 7.72 mm and 8.13 mm in 3D; (2) the sensitivity for true events was 8,567 cps/kBq/cc in 2D and 36,649 cps/kBq/cc in 3D; (3) the scatter fraction was 15% in 2D and 30% in 3D; (4) the peak true events rate, the true events rate at 50% of the system dead-time and the true events rate when equal to the random events rate were 750 kcps at 189.81 kBq/cc, 744 kcps at 186.48 kBq/cc and 686 kcps at 150.59 kBq/cc, respectively, in 2D, and 922 kcps at 44.03 kBq/cc, 834 kcps at 53.28 kBq/cc and 921 kcps at 44.03 kBq/cc in 3D; (5) the noise equivalent count (NEC) peak rate was 270 kcps at 34.38 kBq/cc in 3D, with random coincidences estimated by delayed events. Using the NEMA N-01 standards the main results were: (1) the average transverse and axial spatial resolution (FWHM) at 1 cm and 10 cm off axis was 6.28 (4.56) mm and 6.88 (6.11) mm in 2D, and 6.29 (5.68) mm and 6.82 (6.05) mm in 3D; (2) the average sensitivity for the two radial positions (r=0 cm and r=10 cm) was 1.93 cps/kBq in 2D and 9.12 cps/kBq in 3D; (3) the scatter fraction was 19% in 2D and 45% in 3D; (4) the NEC peak rate was 54 kcps at 46.99 kBq/cc in 2D and 45.5 kcps at 10.84 kBq/cc in 3D, when random coincidences were estimated by using k=2 in the NEC formula, while the NEC peak rate was 81 kcps at 64.43 kBq/cc and 66 kcps at 14.86 kBq/cc in 2D and 3D, respectively, when random coincidences were estimated by using k=1 in the NEC formula. The new integrated PET-CT system Discovery ST has good overall performances in both 2D and 3D, with in particular a high sensitivity and a very good 3D NEC response.