Instruments and related products for measuring and detecting ionizing radiation or radiological dose, including companies that make, manufacture, distribute or sell these devices. Producers and distributors of isotopes or radiological sources for lab or research purposes are not included, but may be found in Science/Instruments_and_Supplies/Isotopes. Instruments relying on radiation sources for purposes such as metrology and well-logging are included in categories related to the application for which the instrument is used, not here.