Meric P, Seylaz J
Med Prog Technol. 1977 Jul 15;5(1):41-6.
The sources of error involved in the measurement of regional cerebral blood flow (rCBF) with radioactive tracers in man have been studied. This report shows that one of the main sources is the weakness of the energy emitted by the tracers used. Clearance curves obtained with scalp detectors are subject to interference: the radiation measured originates not only in the region studied but also, by scattering, from the rest of the brain. Because of the weak energy levels involved, the scattered radiation contributes significantly to the total measured radiation, and for the same reason it is impossible to distinguish clearly the scattered radiation from that arriving directly. These systematic errors in rCBF measurements were studied quantitatively by in vitro tests and computer simulation, and limits were established for resulting alterations of all varialbes determined (grey and white matter flow, mean flow, compartment weight). It was concluded that the biologic origin of a modification of rCBF can be affirmed only in the case of changes of at least 10%.
对人体使用放射性示踪剂测量局部脑血流量（rCBF）时所涉及的误差来源进行了研究。本报告表明，主要误差来源之一是所用示踪剂发射能量较弱。用头皮探测器获得的清除曲线会受到干扰：所测辐射不仅源于所研究区域，还会因散射来自大脑其他部位。由于涉及的能量水平较低，散射辐射对总测量辐射有显著贡献，并且出于同样原因，无法清晰区分散射辐射和直接到达的辐射。通过体外试验和计算机模拟对rCBF测量中的这些系统误差进行了定量研究，并确定了所有测定变量（灰质和白质血流量、平均血流量、室腔重量）变化的限度。得出的结论是，只有在至少有10%的变化时，才能确定rCBF改变的生物学来源。
