A computer tomography apparatus has an x-ray source which is fed with a high voltage supply. Operation of the x-ray source over an extended period of time causes the focal spot on the anode to change position, thereby degrading the image which is constructed from the series of exposures, because construction of the image is based in part upon the focus being at a known position. A focus position computer is therefore provided which receives signals from the high voltage supply corresponding to the operating parameters of the x-ray source. Based on a known relationship between these parameters, the length of operating time, and the expected position of the focus, the focus position computer calculates the expected change in position of the focus, and supplies a signal corresponding to this change to the image construction computer, which takes the change in focus position into account in constructing the image for display.
A computer tomograph apparatus of the type having a rotating frame which carriers an x-ray source and a radiation detector includes a mount for the radiation detector which resiliently seats the radiation detector on the rotating frame permitting slight displacement of the radiation detector in a direction tangent to the orbit of the detector around a patient. The resilient mounting of the radiation detector suppresses the transmission of mechanical jolts and other jarring forces from the rotating frame to the detector. Because of the resilient mounting, the weight of the radiation detector will cause a slight dislocation of the detector during a revolution. To compensate for this dislocation the rated position of the focus is determined dependent upon the detector position, so that the position of the focus can be adjusted corresponding to this detector displacement.
An X-ray detector that includes a sensor matrix and a scintillator arrangement and in which wire elements are spaced apart in layers A and B in order to reduce the crosstalk in neighboring detector elements. Scintillators are inserted at least partly in the grid openings formed.
A computer tomography apparatus has a circular anode and a circular radiation detector in which a patient to be examined is disposed. An electron beam from an electron gun is deflected by a beam deflection system, fed by a line voltage, so that the focus of the electron beam on the anode orbits the patient, thereby irradiating the patient from different angular positions. The radiation attenuated by the patient is recorded by the radiation detector, and corresponding electrical signals are read-out from the radiation detector by a data acquisition system, from which an image of the patient is constructed. To avoid image artifacts due to fluctuations such as ripples in the line voltage which supplies the tomography apparatus, the beam deflection system and the data acquisition system are synchronized so that, at each of n revolutions of the focus, the focus movement and the read-out of the measured values ensue slightly phase-shifted compared to the preceding revolution relative to the ripple period of the line voltage.
An x-ray source assembly and method of operation are provided having enhanced output stability. The assembly includes an anode having a source spot upon which electrons impinge and a control system for controlling position of the anode source spot relative to an output structure. The control system can maintain the anode source spot location relative to the output structure notwithstanding a change in one or more operating conditions of the x-ray source assembly. One aspect of the disclosed invention is most amenable to the analysis of sulfur in petroleum-based fuels.
An x-ray source assembly includes an anode having a spot upon which electrons impinge based on power level supplied to the assembly, and an optic coupled to receive divergent x-rays generated at the spot and transmit output x-rays from the assembly. A control system is provided for maintaining intensity of the output x-rays dynamically during operation of the x-ray source assembly, notwithstanding a change in at least one operating condition of the x-ray source assembly, by changing the power level supplied to the assembly. The control system may include at least one actuator for effecting the change in the power level supplied to the assembly, by, e.g., controlling a power supply associated with the assembly. The control system may also change the temperature and/or the position of the anode to maintain the output intensity.
