Physical performance of a positron tomograph for brain imaging with retractable septa.
Physical performance of a positron tomograph for brain imaging with retractable septa.
复制标题
用于具有可伸缩隔膜的脑部成像的正电子断层扫描仪的物理性能。
DOI：
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发表时间：
1992
影响因子：
3.5
通讯作者：
J. Reed
中科院分区：
文献类型：
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作者：
T. Spinks;T. Jones;Dale L. Bailey;David W. Townsend;S. Grootoonk;P. Bloomfield;M. Gilardi;Michael E. Casey;B. Sipe;J. Reed
研究了一种新型自动收放式脑间隔正电子断层成像的性能特点。该装置由块BGO探测器组成（每个块8 x 8个元素），环直径为76厘米，轴向视场为106.5毫米。在跨轴视场中心18厘米处，静止和摆动采样的面内分辨率平均分别为5.8 mm和5.0 mm （FWHM）。它的独特之处在于在“传统”2D模式（带隔层）或3D模式（隔层缩回）下的数据采集能力，其中16个探测器环之间的任何一个都可以获得数据。当散射事件被减去时，一个直径20厘米的均匀圆柱体的效率在2D（间隔扩展）和3D模式之间总体上增加了4.8倍。对于20厘米的幻影，3D的真/单比高于2D，但对于给定的非散射真率，3D的随机率更高。在380 keV下，20 cm圆柱体内的散射分数为10%（隔膜延伸）和36%（隔膜收缩）。尽管间隔收缩时散射会增加，但3D采集模式效率的提高带来了明显的优势，特别是在许多示踪剂浓度较低的研究中，因此死区时间和随机率不那么重要。
Performance characteristics of a new design of positron tomograph with automatically retractable septa for brain imaging have been studied. The device, consisting of block BGO detectors (8 x 8 elements per block), has a ring diameter of 76 cm and an axial FOV of 106.5 mm. The in-plane resolution is on average 5.8 mm and 5.0 mm (FWHM) for stationary and wobble sampling, respectively, over the central 18 cm of the transaxial FOV. Its unique feature is the capability of data acquisition both in the 'conventional' 2D mode (with septa) or 3D mode (septa retracted) where coincidences between any of the 16 detector rings are acquired. When scattered events are subtracted, the efficiency for a 20 cm diameter uniform cylinder increases overall by a factor of 4.8 between 2D (septa extended) and 3D modes. For a 20 cm phantom the trues/singles ratio is higher for 3D than for 2D but for a given unscattered trues rate, the randoms rate in 3D is higher. At 380 keV the scatter fraction within a 20 cm cylinder is 10% (septa extended) and 36% (retracted). In spite of the increase in scatter when septa are retracted, the increased efficiency in the 3D mode of acquisition yields distinct advantages, particularly in the many studies where tracer concentration is low and consequently where dead time and random rates are less important.