A radiotherapy system includes an X-ray target configured to convert an incident electron beam into a therapeutic X-ray beam, a purging magnet configured to redirect unwanted particles emitted from the X-ray target away from the therapeutic X-ray beam, and a particle collector configured to absorb the unwanted particles subsequent to redirection by the purging magnet. The particle collector may be configured to dissipate at least 50% of the energy of the incident electron beam.

X-ray transparent insulation can be sandwiched between an x-ray window and a ground plate. The x-ray transparent insulation can include aluminum nitride, boron nitride, or polyetherimide. The x-ray transparent insulation can include a curved side. The x-ray transparent insulation can be transparent to x-rays and resistant to x-ray damage, and can have high thermal conductivity. An x-ray window can have high thermal conductivity, high electrical conductivity, high melting point, low cost, and matched coefficient of thermal conductivity with the anode. The x-ray window can be made of tungsten. For consistent x-ray spot size and location, a focusing plate and a filament can be attached to a cathode with an open channel of the focusing plate aligned with a longitudinal dimension of the filament. Tabs of the focusing plate bordering the open channel can be bent to align with a location of the filament.

An electron source irradiates a target by inclining an electron beam at a predetermined irradiation angle θ with respect to a perpendicular to a target substrate. In this way, it is possible to extract grating-shaped X-rays in a direction perpendicular to the target substrate. The target substrate includes a substance containing a light element. On a surface of the target substrate, a plurality of grooves periodically disposed in a one-dimensional or two-dimensional direction to have a grating shape is formed. X-ray generating portions are arranged in a grating shape by being embedded in the plurality of grooves formed in the target substrate. The X-ray generating portions are made of a metal including W, Ta, Pt or Au or an alloy thereof. A depth M of the X-ray generating portions arranged in the grating shape is set within a predetermined range. The generation efficiency of X-rays for phase imaging is improved.

An inspection radiation source is provided. The inspection radiation source includes an electron accelerator for generating an electron current, and a target for the electron current including a first part and a second part. This first part is configured to be at least partly exposed to the electron current on an impact area having a first width in a direction substantially perpendicular to the electron current, and inhibit propagation of the electron current. The second part has a second width in the direction substantially perpendicular to the electron current, the second width of the second part being smaller than the first width of the impact area, the second part being configured to be at least partly exposed to the electron current, and generate inspection radiation by emitting X-rays in response to being exposed to the electron current.

A monolithic housing for an x-ray source can wrap at least partially around a power supply and an x-ray tube. The monolithic housing can include Al, Ca, Cu, Fe, Mg, Mn, Ni, Si, Sr, Zn, or combinations thereof. Mg can be a major component of the monolithic housing. The monolithic housing can be formed by injection molding. The monolithic housing can provide one or more of the following advantages: (a) light weight (for easier transport), (b) high electrical conductivity (to protect the user from electrical shock), (c) high thermal conductivity (to remove heat generated during use), (d) corrosion resistance, (e) high strength, and (f) high electromagnetic interference shielding (to shield power supply components from external noise, to shield other electronic components from power supply noise, or both).

A planar filament 11.sub.f can include multiple materials to increase electron emission in desired directions and to suppress electron emission in undesired directions. The filament 11.sub.f can include a core-material CM between a top-material TM and a bottom-material BM. The top-material TM can have a lowest work function WF.sub.t; the bottom-material BM can have a highest work function WF.sub.b; and the core-material CM can have an intermediate work function WF.sub.c (WF.sub.t<WF.sub.c<WF.sub.b). A width W.sub.t of the filament 11.sub.f at a top-side 31.sub.t can be greater than its width W.sub.b at a bottom-side 31.sub.b (W.sub.t>W.sub.b). This shape makes it easier to coat the edges 31.sub.e with the bottom-material BM, because the edges 31.sub.e tilt toward and partially face the sputter target. This shape also helps direct more electrons to a center of the target 14, and reduce electron emission in undesired directions.

A method for imaging a sample by means of an X-ray detector is disclosed, including providing an electron beam interacting with a target to generate X-ray radiation emitted from an X-ray spot on the target, moving the sample relative to the target, deflecting the electron beam such that the X-ray spot is moved over the target simultaneously and in accordance with the movement of the sample, and detecting X-ray radiation emitted from the X-ray spot and interacting with the sample.

An x-ray generating unit includes an x-ray tube that is substantially transparent to x-rays and that defines a vacuum therein. A cathode is disposed within the x-ray tube and defines a plurality of spaced apart cavities. An anode is spaced apart from the cathode and includes a material that emits x-rays when impacted by electrons. A plurality of filaments is each disposed in a different one of the cavities defined by the cathode and each is electrically coupled to the cathode. Each filament emits a focused electron beam directed to a different predetermined spot on the anode upon application of a predetermined voltage between the cathode and the anode, thereby causing the anode to generate x-rays.

A planar filament 11.sub.f can include multiple materials to increase electron emission in desired directions and to suppress electron emission in undesired directions. The filament 11.sub.f can include a core-material CM between a top-material TM and a bottom-material BM. The top-material TM can have a lowest work function WF.sub.t; the bottom-material BM can have a highest work function WF.sub.b; and the core-material CM can have an intermediate work function WF.sub.c(WF.sub.t<WF.sub.c<WF.sub.b). A width W.sub.t of the filament 11.sub.f at a top-side 31.sub.t can be greater than its width W.sub.b at a bottom-side 31.sub.b (W.sub.t>W.sub.b). This shape makes it easier to coat the edges 31.sub.e with the bottom-material BM, because the edges 31.sub.e tilt toward and partially face the sputter target. This shape also helps direct more electrons to a center of the target 14, and reduce electron emission in undesired directions.

An x-ray apparatus includes a vacuum chamber that includes a window for exit of x-rays. Electrons are generated at a cathode within the vacuum chamber and accelerated toward a target anode associated with the window. An x-ray generating layer is included as a surface of the target anode to receive the electrons emitted by the cathode and to create x-rays. A blocking path blocks over 70% of the free electrons reaching said target anode from continuing on to exit through the window, while allowing x-rays leaving the x-ray generating layer to continue along the selectively blocking path to exit through the window. The x-ray apparatus is capable of operating at low voltage and relatively high power to reduce the necessary shielding and the corresponding weight of the apparatus yet allow more ready absorption of x-rays by items being irradiated.