These signals are accumulated for quantitative measurements. As shown in Fig. 23,the detector head is usually located over a single track and measures the simultaneous emission of radiation from all zones in that track before automatic repositioning over the next track to be evaluated. Phosphor imaging provides high sensitivity, high resolution,short analysis times with relatively low cost, and is frequently the preferred method for detecting labeled compounds on thin-layerplates. The phosphor imaging plate consists of a flexible polymeric film coated with crystals of a photostimulatable phosphor material (e.g., a lanthanum-doped inorganic salt).