X-ray generating tube, X-ray generating apparatus, and radiography system

An X-ray generating tube comprising:

• an insulating tube having a pair of ends in a tube axial direction;
• a cathode connected to the one end of the insulating tube and comprising:
• an electron emitting source having an electron emitting portion configured to irradiate an electron beam;
• and
• a cathode member electrically connected to the electron emitting source;
• and
• an anode connected to the other end of the insulating tube and comprising:
• a target configured to generate an X-ray upon an irradiation with the electron beam;
• an anode member which is electrically connected to the target and which holds the target;
• a joining member configured to connect the insulating tube and the anode, and located therebetween;
• an outer anode sleeve protruding along the insulating tube from a peripheral portion of the anode member configured to be hermetically connected to the insulating tube via the joining member;
• and
• an end surface conductive layer provided on the other end of the insulating tube,
• wherein the end surface conductive layer is provided on the other end of the insulating tube configured to be in contact with the anode member at a plurality of regions in a tube circumference direction of the insulating tube and increase a probability of contact between the end surface conductive layer and the anode member.