ASIT Gamma-Ray Camera : A New Camera Head Provided with an Array of Scintillation Intensifier Tubes

After a brief examination of the main physical and technological problems which determine the limits of performance of various kinds of scintillation cameras, a new gamma camera is suggested in this paper. The detection head is composed of an array of scintillation intensifier tubes (ASIT), the bialkali photocathodes of which are closely coupled to a large NaI (Tl) scintillator plate. The output phosphor (P 47) screens of the intensifiers emit blue light pulses collected by a conventional event localizer which includes an array of photomultiplier tubes and an electronic calculator. A description of the basic operation of an ASIT gamma camera indicates that the event coordinates result from a barycentric estimation of the spatial distribution of detected light photons emitted from the scintillation. A computer simulation made to estimate the performance parameters of ASIT cameras shows that high intrinsic spatial and spectral resolutions can be reached. For a particular camera head design, 2.3 mm and 11.3 KeV FWHM at 122 KeV are obtained.