Dot focus and belt focus change possible X-ray tube sphere

摘要

PURPOSE:To make it possible to allow switch-over between point focus and line focus only with an electron gun rotated by 90 deg. by forming the cooling water injection opening of a target into a cross shape, and thereby mounting the electron gun rotatably. CONSTITUTION:The cooling water injection opening 26 of the back side of a target face 28 to which electron beams are struck is formed into a cross shape, and an electron gun is rotatably mounted onto a vacuum container. The target face 25 is sufficiently cooled by the injection opening 26 in the range of the cross shape. Electron beams 34 emitted from a filament 32 are struck against the target face 28 in a form of a line extending to the vertical direction so that X-rays 38 of line focus are obtained. When the electron gun 16 is rotated clockwise by 90 deg., the filament 32 is rotated clockwise by 90 deg. so as to let the election beams 34 emitted form a line extending to the horizontal direction so that X-rays of point focus may be obtained. By this constitution, a X-ray tubular bulb 10 can be obtained, which makes it possible to allow switch-over between point focus and line focus in the same direction in a simple manner.