A simple and inexpensive method for the recording of scintillation camera data at low and moderate count rates

In a small routine nuclear medicine department the majority of imaging on a gamma camera involves count rates within about 15 000 CPS. The analogue approach described enables images within this range to be recorded without loss of uniformity or resolution. The equipment needed is only two channels per isotope of an instrumentation recorder and simple additional pulse shaping circuitry. For information about an area of interest simple comparators and a pen recorder may be used. The major cost would be the instrumentation recorder (at present a suitable 40 kHz machine is available for about 3000 lbs.). The additional electronics may be quite easily built in a small department at nominal cost, and the rate meter and pen recorder are likely to be found in most departments. The approach has gross limitations and could not be used for studies above about 20 000 CPS, it would only be suitable for slow dynamic studies such as renograms, but the simplicity of the method, the immediate replay on site, and almost instant quantitative data after a patient study without any need for programming, together with the very low cost, make this system attractive for a small routine department without access to a digital computer.