THE ECAT EXACT HR - PERFORMANCE OF A NEW HIGH-RESOLUTION POSITRON SCANNER
THE ECAT EXACT HR - PERFORMANCE OF A NEW HIGH-RESOLUTION POSITRON SCANNER
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DOI：
10.1097/00004728-199401000-00023
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发表时间：
1994-01-01
影响因子：
1.3
通讯作者：
HEISS, WD
中科院分区：
文献类型：
--
作者：
WIENHARD, K;DAHLBOM, M;HEISS, WD
目的：ECAT Exact HR是西门子公司新近研制的一种高空间分辨率的正电子发射计算机断层扫描仪。材料和方法：新的断层扫描仪由112个BGO块探测器组成，每个环50 mm×23 mm×30 mm深，覆盖15 cm的轴向视野，病人口直径56 cm。每个模块被锯成一个8×7的矩阵，得到24个探测器环，每个环有784个晶体。结果：一个20 cm的圆柱体模型在二维(2D)模式下的总灵敏度为177 kCPS/mU Ci/ml，在3D模式下增加到1.46 Mcps/mU Ci/ml。研究了不同低能量鉴别器阈值下的计数性能。与2D和3D模式下的精确系统相比，较小的探测器块可将噪声当量计数提高近50%。对于直径为20厘米的体模的线源，对于450到250 keV的能量阈值，散射分数在2D范围内从0.09到0.13变化。在3D模式下，观察到散射度增加了3倍。横断面空间分辨率从中心的3.6 mm半高宽(FWHM)到R=20 cm处的切向半高宽4.5 mm和径向半高宽7.4 mm不等。平均轴向分辨率从中心的4.0 mm半高宽变为R=20 cm时的6.7 mm半高宽。结论：由于其特殊的性质，高分辨率成像同样可以应用于临床常规的脑和全身成像，以及对中型动物局部示踪剂浓度的无创性实验研究
Objective: The ECAT EXACT HR is a newly designed CTI-Siemens PET scanner with high spatial resolution. Its physical performance with respect to resolution, count rate efficiency, and scatter was investigated and evaluated with phantom studies.Materials and Methods: The new tomograph consists of three rings of 112 BGO block detectors (50 mm x 23 mm x 30 mm deep) each, covering an axial field of view of 15 cm with a patient port of 56 cm diameter. Each block is sawed into an 8 x 7 matrix giving 24 detector rings with 784 crystals each.Results: Total sensitivity for a 20 cm cylinder phantom is 177 kcps/mu Ci/ml in two-dimensional (2D) mode and increases to 1.46 Mcps/mu Ci/ml in 3D mode. Count rate performance was investigated for different low energy discriminator thresholds. Smaller detector blocks improve noise equivalent counts by similar to 50% compared with the EXACT system both in 2D and in 3D mode. Scatter fractions vary in 2D from 0.09 to 0.13 for energy thresholds from 450 to 250 keV for line sources in a 20 cm diameter phantom. In 3D mode an increase of scatter by a factor of 3 is observed. Transaxial spatial resolution varies from 3.6 mm full width at half-maximum (FWHM) at the center to 4.5 mm FWHM tangentially and 7.4 mm FWHM radially at R = 20 cm. Average axial resolution changes from 4.0 mm FWHM at center to 6.7 mm FWHM at R = 20 cm.Conclusion: Due to its special properties, the EXACT HR can be equally applied to routine clinical brain and whole-body imaging and to noninvasive experimental studies of regional tracer concentrations in medium-sized animals