The emission characteristics of graphite nanospines (GNSs) encapsulated in an x-ray tube with a system for controlling electric field crowding (SCEFC) are investigated. GNSs encapsulated in an x-ray tube can be driven at an anode current (I-A) of more than 1 mA. Further, I-A can be controlled using the SCEFC. During the operation of the x-ray tube with GNSs and the SCEFC at the anode voltage of 12.5 kV and I-A of 640 mu A for 100 h, there was no degradation in I-A. The noise current superimposed on I-A was observed to be +/- 34.5 mu A. It was reduced to +/- 1.62 mu A by using the SCEFC. The authors also demonstrated radiography and x-ray fluorescence measurement as applications of x-ray tubes with GNSs and the SCEFC.