A METHOD FOR MEASURING THE ABSOLUTE SENSITIVITY OF POSITRON EMISSION TOMOGRAPHIC SCANNERS
A METHOD FOR MEASURING THE ABSOLUTE SENSITIVITY OF POSITRON EMISSION TOMOGRAPHIC SCANNERS
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DOI：
10.1007/bf02258426
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发表时间：
1991-06-01
期刊：
影响因子：
--
通讯作者：
SPINKS, TJ
中科院分区：
文献类型：
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作者：
BAILEY, DL;JONES, T;SPINKS, TJ
需要以计数s-1.MBq-1为单位测量正电子发射断层扫描(PET)扫描仪的绝对灵敏度。目前，灵敏度通常是通过测量已知浓度的放射性核素分布在充满水的圆柱形体模中来确定的，圆柱体体模的直径通常为20厘米。测量受到光源的自衰减和圆柱体内的散射的干扰，不能给出真正的绝对灵敏度测量。由于这些因素的大小和处理方式不同，很难在不同制造商的扫描仪之间进行有意义的比较，也很难在不同的采集几何结构之间进行比较(例如，存在和不存在平面间隔膜)。我们实验室已经开发出一种方法，可以为扫描仪提供空气中绝对灵敏度的测量，而不受光源内的衰减和散射的影响。该方法包括测量包含在铝外壳内的细线氟源18，在该铝外壳上添加了连续的铝套。这些测量的外推允许进行有效的计数。s-1.MBq-1测量零厚度的铝。对于有平面间隔和无平面间隔的全身PET扫描仪，其绝对灵敏度分别为3926±1.MBq~(-1)(0.39%效率)、5079±1.MBq~(-1)(0.51%)和32312±1.MBq~(-1)(3.2%)。
A need exists to measure the absolute sensitivity of a positron emission tomographic (PET) scanner in units of counts.s-1.MBq-1. At present sensitivity is generally determined by measurement of a radionuclide of known concentration distributed in a water-filled cylindrical phantom, usually 20 cm in diameter. The measurement is confounded by self-attenuation of the source and scatter within the cylinder and does not give a true absolute sensitivity measurement. Due to variations in the magnitude and treatment of these factors, meaningful comparison between different manufacturer's scanners is difficult, as are comparisons between different acquisition geometries (e.g. with and without interplane septa present). A method has been developed in our laboratory that provides measurements of absolute sensitivity in air for a scanner independent of attenuation and scatter within the source. The method involves measurements of a thin-line source of fluorine 18 contained within an aluminium housing to which successive aluminium sleeves are added. The extrapolation of these measurements allows an effective counts.s-1.MBq-1 measurement to be made for zero thickness of aluminium. Measurements have yielded absolute sensitivities of 3926 +/- 61 counts.s-1.MBq-1 (0.39% efficiency), 5079 +/- 26 counts.s-1.MBq-1 (0.51%), and 32312 +/- 544 counts.s-1.MBq-1 (3.2%) for a whole-body PET scanner with interplane septa and for a NeuroPET operating with and without interplane septa, respectively.