A computerised scanner for bidimensional radiochromatograms

Abstract

A computerised automatic scanner for the quantitative evaluation of paper radiochromatograms is described. In this instrument the paper chromatogram is held in a frame, vertically moveable, between two gas flow counters. The scanning operation is performed by moving the counters horizontally across the paper radiochromatograms, discontinuously exploring unit areas for programmed time periods, the period depending on the level of radioactivity. At the end of each line, the counters are made to return to their position of origin and simultaneously the radiochromatogram is moved vertically upwards to the next line of exploration. The coordinate positions, radioactive counts and time for each unit area are recorded on paper tape. Control and read-out of the coordinate positions is effected photo-electrically, employing perforated code plates. A battery of up to ten scanners can be used simultaneously. The scanners are arranged in a time sharing system so that a single tape punch is used for all machines. The punch tape is processed using a programme which gives, for each machine, number map representation of the radioactive spots on the chromatogram, together with automatically computed spot totals of absolute radioactivity. Mechanical construction details and schematic electronic circuits are presented together with performance data.