[Isocount scanning of the brain (author's transl)]

It is well known that the gamma ray emitted by a radionuclide is a Poisson process, so its statistic nature should be taken in consideration when the scintiscanning is performed. But very few attempts have been done from this point of view. After examining in detail the imaging pulse charactristics, the authors introduced a mean for evaluating the fidelity of the collected data, and based on this criterion, pointed out some problems in the conventional scanning method and finally described a statistical way of improving the scintigram. In the present investigation, as a measure of the stochastic fidelity of the scanned data the relative deviation eplision(n) = sigma(n)/E(n) is introduced; sigma is the standard deviation and E(n) is the expectation value of the counting rate. In the conventional scanning in which the detector moves with a costant speed, the relative deviation varies from area to area according to the concentration of the radioisotope in the brain. In the so-called cold area of the brain scintigram, the relative deviation fluctuates remarkably because of a rather low density of radioisotope in this area.