The detection of compounds labeled with radioisotopes after separation by thin-layer chromatography requires special equipment, laboratory facilities, and compliance practices. Consequently,it is a method restricted to laboratories with a suitable infrastructure and trained operators. Common applications include the assay of radio pharmaceuticals and medical diagnostic agents and studies of the fate, distribution and modification of labeled compounds in biological and environmental systems. Thin-layer chromatography is often the preferred option for these applications because it can tolerate the application of dirty samples and all radioactivity applied to the layer is available for detection.