Patent ID: 7634054

Claim:
An X-ray tube comprising: a vacuum casing including an interior in a vacuum state and a window section formed of an X-ray transmission film through which an X-ray is transmitted; an electron beam source provided in the vacuum casing to emit an electron beam; a target irradiated with the electron beam to generate a primary X-ray and to emit the generated primary X-ray through the window section to an exterior sample, the target being provided on the window section and having an outer diameter smaller than that of the window section; an X-ray detection element provided in the vacuum casing to detect a fluorescent X-ray and a scattered X-ray, the fluorescent X-ray and the scattered X-ray being emitted from the sample to be incident through the window section, to output a signal containing energy information of the fluorescent X-ray and the scattered X-ray; and a guard part provided between the X-ray detection element and an irradiated area of the target with the electron beam.