methods for rapid detection of the maximum likelihood estimator with a gamma camera.

摘要

In a method of localising a scintillation event in a gamma camera, having a number of photomultipliers (PM1, PMi, PMN) arranged over a camera area, a location-dependent probability function (L(x, y), LL(x, y)) is formed from their output signals (S1, Si, SN) together with the sets of reference signals (@1, @i, @N) which have been obtained from reference scintillation events with origins of known location. The location of the maximum of the probability function is registered as the location of the scintillation event. According to the invention, in a first localising method an approximate preliminary localisation is used first of all to specify a camera subarea in which the location of the scintillation event is likely to lie with a high degree of probability and in which the location of the scintillation event is then determined with the aid of the probability function. According to the invention, in a second localising method the camera subarea (50) is subdivided into mutually overlapping camera subareas (52, 54, 56, 58). Within each subarea, the probability function is determined at a point (60, 62, 64, 66). The subarea in which the probability function has the greatest value is further subdivided into mutually overlapping camera subareas. The subdividing is interrupted when the side lengths of the camera subareas have reached the interval (Wx) between the reference scintillation events. The localising methods permit rapid and accurate localisation even in cases of large camera subareas with a large number of photomultipliers. …IMAGE…