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In early and basic X-ray equipment, the applied voltage varies cyclically, with one, two, or more pulses per mains AC power cycle. One standard way to measure pulsating DC is its peak amplitude, hence kVp. Most modern X-ray generators apply a constant potential across the X-ray tube; in such systems, the kVp and the steady-state kV are identical.
In general, an X-ray's beam intensity is not uniform. When it focuses to a target, a conical shape appears (divergent beam). The intensity of the beam from the positive anode side is lower than the intensity from the negative cathode side because the photons created when the electrons strike the target have a longer way to travel through the rotating target on the anode side.
X-ray optics is the branch of optics dealing with X-rays, rather than visible light.It deals with focusing and other ways of manipulating the X-ray beams for research techniques such as X-ray diffraction, X-ray crystallography, X-ray fluorescence, small-angle X-ray scattering, X-ray microscopy, X-ray phase-contrast imaging, and X-ray astronomy.
An X-ray generator generally contains an X-ray tube to produce the X-rays. Possibly, radioisotopes can also be used to generate X-rays. [1]An X-ray tube is a simple vacuum tube that contains a cathode, which directs a stream of electrons into a vacuum, and an anode, which collects the electrons and is made of tungsten to evacuate the heat generated by the collision.
An illustration of the heel effect in an x-ray tube. In X-ray tubes, the heel effect or, more precisely, the anode heel effect is a variation of the intensity of X-rays emitted by the anode depending on the direction of emission along the anode-cathode axis. X-rays emitted toward the anode are less intense than those emitted perpendicular to ...
The photo-absorption strongly depends on the atomic number of the material and the X-ray energy. Several centimeter thick volumes can be accessed in steel and millimeters in lead containing samples. No radiation damage of the sample, which can pin incommensurations or destroy the chemical compound to be analyzed.
The X-ray photons are produced by colliding a high current, narrow beam of electrons with a tungsten target. The X-rays are then passed through a flattening filter, and then measured using an X-ray ion chamber. The flattening filter resembles an inverted ice-cream cone, and it shapes and attenuates the X-rays. The electron beam current required ...
As an example, each mm 2 of a CT detector may receive several hundred million photon interactions per second during a scan. [4] To avoid saturation in areas where little material is present between the X-ray source and the detector, the pulse resolving time must be small compared to the average time between photon interactions in a pixel.