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    X-ray tube providing variable imaging spot size
    2.
    发明授权
    X-ray tube providing variable imaging spot size 失效
    X射线管提供可变成像光斑尺寸

    公开(公告)号：US06236713B1

    公开(公告)日：2001-05-22

    申请号：US09179805

    申请日：1998-10-27

    申请人： Richard B. True ,  James C. Taylor ,  Christopher P. Ferrari ,  Curtis G. Allen ,  Thomas M. Bemis

    发明人： Richard B. True ,  James C. Taylor ,  Christopher P. Ferrari ,  Curtis G. Allen ,  Thomas M. Bemis

    IPC分类号： H01J3514

    CPC分类号： H01J35/06 ,  H01J3/12 ,  H01J35/14

    摘要： A variable spot size x-ray tube comprises a cathode having an electron emitting surface providing an electron beam that travels essentially along the tube axis of symmetry to an anode. The anode, spaced from the cathode, includes a target, the front surface of which is disposed at an oblique angle with respect to the axis of symmetry. The potential of the anode is generally positive with respect to that of the cathode. The cathode is heated to a temperature at which electrons are emitted by the thermionic emission process. Current from the cathode can be controlled by varying the cathode temperature if the cathode is operated in the temperature limited region. The incident electron beam forms a spot on the target surface whereupon x-rays are produced in response to impingement of the electron beam on the target. The x-rays propagate outwardly from the target spot through a vacuum window to form a beam of x-radiation outside the x-ray tube. An aperture grid is disposed between the cathode and the anode, and has a central aperture permitting the electron beam to pass therethrough. The aperture grid further has a variable voltage applied to it which may be positive, negative, or equal to the potential of the cathode. The voltage on the control grid is used to control the diameter of the electron beam which impinges upon the target. Specifically, the electron beam diameter varies in correspondence with the variable aperture grid voltage, and selective variation of the electron beam diameter results in a corresponding variation in size of the x-ray imaging spot.

    摘要翻译： 可变点尺寸x射线管包括具有电子发射表面的阴极，该电子发射表面提供基本上沿着管对称轴线向阳极行进的电子束。 与阴极间隔开的阳极包括靶，其前表面相对于对称轴线倾斜设置。 阳极的电位通常相对于阴极的电位为正。 将阴极加热到通过热离子发射过程发射电子的温度。 如果阴极在温度限制区域中运行，则可以通过改变阴极温度来控制来自阴极的电流。 入射的电子束在目标表面上形成一个点，因此响应于电子束撞击靶而产生X射线。 x射线从靶点向外传播通过真空窗口，以在x射线管外部形成x辐射束。 孔栅格设置在阴极和阳极之间，并且具有允许电子束通过的中心孔。 孔径栅格还具有施加到其上的可变电压，其可以是正的，负的或等于阴极的电位。 控制网格上的电压用于控制撞击目标的电子束的直径。 具体地，电子束直径与可变孔径栅极电压相对应地变化，并且电子束直径的选择性变化导致x射线成像光斑的尺寸的相应变化。