Cathode Ray Tube (Crt) 5 : A vacuum tube with a luminescent screen often used for viewing ultrasonic echo signals or for video readout of computer stored data. (RP 5A5)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}