Investigation of noise equivalent count rate in positron imaging using a dual head gamma camera
Investigation of noise equivalent count rate in positron imaging using a dual head gamma camera
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使用双头伽玛相机研究正电子成像中的噪声等效计数率
DOI：
10.1109/nssmic.1997.670529
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
B. Bendriem
中科院分区：
文献类型：
--
作者：
D. Brasse;M. Tararine;O. Lamer;B. Bendriem
在正电子成像中，噪声等效计数（NEC）率曲线提供了图像质量与散射、随机和真实符合率之间的良好联系。NEC曲线已在SophyCamera DST（SMV）上测量，其中20 cm圆柱体模填充有/sup 18/F（59 MBq）。在该系统上，视场由两个相距720 mm的矩形平行探测器（400*300 mm）确定。每个闪烁探测器由3/8英寸厚的NaI（Tl）晶体组成。符合时间窗口设定为15 ns。使用PET NEMA方案测量散射分数（sf）。在/sup 18/F的6个半衰期内，使用两个20%能量窗口（中心为511 keV（Peak）和417 keV（Compton））进行断层扫描采集，测量随机和符合计数率。延迟信号从一个符合检测器（45 ns）允许调查随机符合率。系统灵敏度测量为NEC曲线原点处的斜率。NEC率峰值分别为199 cps和252 cps，分别为199 cps（0.20 sf）和199 cps +Compton（0.28 sf）符合。在1.33 kBq/cc至1.85 kBq/cc的活性浓度值范围内达到这些最大值。灵敏度提高了1.3倍，NEC率始终更高，当使用峰值+康普顿符合时，图像质量得到改善。
In positron imaging, Noise Equivalent Count (NEC) rate curves provide a good link between image quality and scatter, random and true coincidence rates. The NEC curve has been measured on a SophyCamera DST (SMV) with a 20 cm cylinder phantom filled with /sup 18/F (59 MBq). On that system, the field of view is determined by two rectangular parallel detectors (400*300 mm) separated by 720 mm. Each scintillation detector is composed of a 3/8 inch thick NaI(Tl) crystal. The coincidence time window was set to 15 ns. The scatter fraction (sf) was measured using PET NEMA protocol. Random and coincident count rates were measured using tomographic acquisition with two 20% energy windows centered on 511 keV (photopeak) and 417 keV (Compton) over 6 half-lives of /sup 18/F. Delaying signals from one of the coincident detectors (45 ns) allowed to investigate random coincidence rate. System sensitivity was measured as the slope at the origin of the NEC curve. The NEC rate peaked at 199 cps and 252 cps for photopeak (with a 0.20 sf) and photopeak+Compton (with 0.28 sf) coincidences respectively. These maxima were reached over activity concentration values ranging from 1.33 kBq/cc to 1.85 kBq/cc. With a sensitivity 1.3 times better, a NEC rate always greater, image quality improves when using photopeak+Compton coincidences.