Microchannel array detector for quantitative electronic radioautography.

The microchannel array detector provides direct electronic detection and real time imaging of radioactive tracers in samples that traditionally have been imaged by film radioautography. The technology of the detector is described, and the main benefits of this new technology, speed and precise quantitation, are illustrated with practical results. The instrument response to a 14C dilution series (range of 10(5)) was linear over the whole range. Results from the microchannel array detector are compared to results obtained with liquid scintillation counting (LSC) and densitometry of film radioautographs. Because the instrument response is linear and consistent from day to day, it is not necessary to routinely include calibration standards as is required for film. The 14C counting efficiency was found to be essentially constant for different tissues in a whole body microtome section. As with LSC, results reported as counts per min. (CPM) are independent of counting time. Quantitative results were obtained with assays for chloramphenicol acetyl transferase in two min. and little as 0.2 DPM/mm2 of 32P was detected in seven min.