A portable instrument for scintigraphic recording of blood volume shifts

A portable scintigraphic instrument for continuous recording of intravascular blood shift at several sites was developed. It consists of several (up to six) miniature scintillation detectors with integrated preamplifier, their relevant electronic chains (gaussian shaping amplifier and threshold discriminator), six 16-bit counters, a large memory and a microcontroller that generates the time base, reads the counters and transfers the data to the memory. The activity data that correspond to intravascular volume shifts can be collected for more than 24 hours and then transferred to a computer for analysis. The small size and weight of the instrument and the absence of any data link to the computer in the data acquisition phase make it possible to apply the scintigraphic technique during common daily activities.