Abstract: A method for regulating a scan dosage includes generating an initial technique command based on default patient size or the previous exposure and on completion of exposure, receiving the actual technique signal. A target entrance dose signal is determined based a default patient size, and tube current is regulated in response to the target entrance dose signal and dose feedback. Image brightness is independently controlled in response to the target entrance dose and average image brightness. An object size is estimated based on the actual technique signal and an image brightness feedback. An optimized generator technique is defined based on estimated object size to achieve a target image quality for the user selected contrast material.

Abstract: In a method to detect the pressure in an x-ray tube having a cathode of the x-ray tube that is heated with a heater current, and wherein electrons are accelerated between the cathode and an anode by an applied x-ray tube voltage, the heater current is measured, a tube current corresponding to the tube -ray voltage is measured, the difference between the measured heater current and the measured tube current is determined or the temporal change of the measured heater current or of the measured tube current is determined, the difference or the temporal change is compared with predetermined calibration values, and a value representing the pressure in the x-ray tube is determined from the comparison.

Abstract: In a method for controlling the modulation of the tube current of an X-ray tube in the production of images using computed tomography, a single topogram of the examination subject is obtained and an orthogonal attenuation value is calculated therefrom, also making use of geometrical information associated with the position of the table on which the examination subject is disposed. In a subsequently-obtained computed tomography scan, the tube current is controlled using the orthogonal patient attenuation.

Abstract: A system and method of medical imaging is designed to reduce a patient's X-ray exposure during scanning. The system automatically generates a default noise index from a received set of scan parameter values that specifies a desired tube current of an X-ray source to use during the scanning of a patient. The default noise index can then be overridden to select a preferred noise index based upon a desired diagnostic quality for a particular volume of interest (VOI) and a diagnostic objective.

Abstract: A compact X-ray source is disclosed, improving controllability and insulation from unwanted high voltage effects. In one aspect, an active variable conductance device (130, 330) connected in series with the cathode is used in a closed loop, feedback arrangement to control the cathode beam current; the current flowing through the device to the cathode being directly sensed and compared with a desired current level. The result of the comparison is used to control the conductance of the device, thereby directly influencing the cathode current. A second aspect provides an extension of a Faraday cage, whereby the secondary winding of a transformer used to supply power to components within the cage is shielded within a coaxial, tubular member connected to the cage and extending outwardly from it.

Abstract: A method for determining the heating time constant of a cathode of an X-ray tube. The value of a boost current applied during a preliminary period must be a function of both a pre-existing heating holding current and a service current to be used subsequently. A model of evolution of cathode temperature produces a minimizing tube current error between a tube current that is expected for the tube and a tube current obtained. The model requires only four parameters that need to be computed.

Abstract: A method, system and medium for modulating the x-ray power of an imaging system so as to maintain a desired image noise in the imaging system is disclosed. In an exemplary embodiment, the method includes obtaining projection data, correcting the projection data responsive to beam hardening errors so as to create corrected projection data, processing the corrected projection data so as to create a plurality of emitter current values responsive to an imaging method and applying the emitter current values to the imaging system responsive to an object to be imaged. In another aspect, a method for determining an optimum emitter tube voltage for an imaging system includes characterizing the imaging system so as to determine a system water-equivalent path length responsive to a relative noise increase.

Abstract: A circuit arrangement for generating an X-ray tube voltage is described, wherein a switching device, connected downstream of a voltage controller (Gsu) and a oscillating current controller (Gri), operable to compare a first controlling variable value (Yu(t)) and a second controlling variable value (Yz(t)) and is operable to send the lesser of the first and second controlling variable values (Yu(t) and Yz(t) onward as a resultant controlling variable value (Y(t)) to the inverse rectifier circuit (Gsi).

Abstract: A method for regulating a scan dosage includes generating an initial technique command based on default patient size or the previous exposure and on completion of exposure, receiving the actual technique signal. A target entrance dose signal is determined based a default patient size, and tube current is regulated in response to the target entrance dose signal and dose feedback. Image brightness is independently controlled in response to the target entrance dose and average image brightness. An object size is estimated based on the actual technique signal and an image brightness feedback. An optimized generator technique is defined based on estimated object size to achieve a target image quality for the user selected contrast material.

Abstract: An x-ray tube emits X-rays in response to a current control signal. An X-ray detector detects the emitted X-rays and provides a detected X-ray signal indicative thereof to a control system, which provides the current control signal. The X-ray detector provides feedback stabilization of the X-ray output from a source of X-rays, such as, for example an X-ray tube. The detector produces an electrical signal proportional to the X-ray output of the X-ray tube, and that signal is used to control the electron beam current in the tube in order to stabilize the X-ray output of the tube at a predetermined value.

Abstract: Methods and apparatus for independent control of electron emission current and x-ray energy in x-ray tubes are provided. The independent control can be accomplished by adjusting the distance between the cathode and anode. The independent control can also be accomplished by adjusting the temperature of the cathode. The independent control can also be accomplished by optical excitation of the cathode. The cathode can include field emissive materials such as carbon nanotubes.

Abstract: An apparatus and method used in dental panoramic and cephalographic x-ray equipment provides automatic adjustment of the pre-programmed exposure factors in order to obtain optimisation of the grey scale of the latent image on various kinds of x-ray detectors, such as the radiographic film or x-ray image detector plates. A sensor, such as photo diodes, detects the intensity of the radiation passed through the patient and incident on the x-ray detector and feeds it to a control unit. The control unit provides a computed simulation of the latent image grey level and adjusts the programmed exposure factors in order to establish the grey level of the latent image at the required reference value.

Abstract: A method described includes positioning an x-ray emitter at a treatment area, where the x-ray emitter is connected to a cable, setting a voltage source at a source voltage, and measuring a current through the x-ray emitter. The method may include comparing a current flowing through the emitter with a limit and a low limit. The method further includes increasing the source voltage if the current is higher than the high limit. The method includes determining the high limit and the low limit based on the source voltage and the desired radiation. An apparatus of the invention includes an x-ray emitter with a voltage source and a current sensor. The apparatus may include a current comparison device for comparing the measured current with a high limit and a low limit, and further include a voltage source control. A current integrator for integrating a current from the x-ray emitter may also be included.

Abstract: A method described includes positioning an x-ray emitter at a treatment area, where the x-ray emitter is connected to a cable, setting a voltage source at a source voltage, and measuring a current through the x-ray emitter. The method may include comparing a current flowing through the emitter with a high limit and a low limit. The method further includes increasing the source voltage if the current is lower than the low limit. The method further includes decreasing the source voltage if the current is higher than the high limit. The method includes determining the high limit and the low limit based on the source voltage and the desired radiation.

Abstract: In a method and x-ray system for controlling the electron current in an x-ray tube emitted from a continuously heated electron emitter with an allocated focussing electrode to an anode, the potential of the focussing electrode is pulsed between a conducting-state voltage, selected dependent on the desired size of the focal spot and/or the tube voltage of the electron beam on the anode, and a blocking voltage interrupting the electron current to the anode, the pulsewidth being modulated to control the electron current.

Abstract: An X-ray generator for powering an X-ray tube, has at least two electron sources for forming focal spots of different sizes at the same area of the anode. The resolution can be adapted to relevant requirements by associating each electron source with a respective control unit which produces an electron flow between the associated electron source and the anode, which flow is dependent on a control signal at a control input of the control unit, the two control units being activatable during an X-ray exposure and each control signal being adjustable, and hence also the ratio of the mAs products supplied by the electron sources.

Abstract: A method for modulating the intensity of an x-ray beam in an x-ray inspection system so as to maintain the highest penetration power and optimum image quality subject to keeping the ambient radiation generated by the x-rays below a specified standard.

Abstract: A high voltage power supply includes a high voltage high frequency generator (10) having outputs (12, 14). An arc limiting device (20) is connected in series to the outputs (12, 14) of the generator (10). The arc limiting device (20) includes two coils (22, 24) of a wound length of wire (50) that exhibit a skin effect. The skin effect forces higher frequency current components to flow at a surface of the wire (50) through a limited skin layer portion (62) of a cross section of the wire (50). In one preferred embodiment, the arc limiting device (20) is connected via high voltage cables (32, 34) with an x-ray tube (40). Suitable material for the wire (50) includes those materials with high permeability to resistivity ratios, for example iron, purified iron, 78 permalloy, 4-97 permalloy, mu metal, or supermalloy.

Abstract: An X-ray apparatus includes an X-ray source with an X-ray tube (2) arranged in a protective tube housing (1) and a filament converter which is connected to the cathode (3) of the X-ray tube (2) and accommodated in the protective tube housing (1). Because of its volume, the filament converter usually cannot be accommodated in the protective tube housing (1) of conventional X-ray apparatus unless major structural modifications are made. However, the use of attenuated high-voltage cables at the cathode side is then impossible still. The invention utilizes a filament converter in the form of a coreless filament transformer (14, 15, 16, 17) and the primary coil (14, 16) of the filament transformer is arranged so as to be coaxial with the secondary coil (15, 17) of the filament transformer. Moreover, the two coils are arranged around a carrier (5, 10), which is preferably the high-voltage connection socket (10) or the tube neck (5).

Abstract: A cathode system for an x-ray tube has an electron emitter and a further electrode arranged between electron emitter and the x-ray tube anode. This further electrode can be connected to a potential deviating from the potential of the electron emitter with a switching stage having a pulse-pause (on-off) ratio set to produce the desired tube current.

Abstract: It is an object of the present invention to provide an x-ray diffractometer for measuring an x-ray diffraction pattern obtained by irradiating x-rays 6 to a sample 7, in which, even though irradiation/non-irradiation of x-rays 6 to the sample 7 are repeated, a target in an x-ray tube bulb 1 is not contaminated and a filament 3 is not thermally stressed, thus improving the practical lifetime of the x-ray tube bulb 1. To achieve this object, the x-ray diffractometer of the present invention is arranged such that x-ray irradiation/non-irradiation selecting means 17 is arranged to switch states of supply and non-supply of a tube voltage to the x-ray tube bulb 1, and that an x-ray generating power source device 11 comprises filament preliminary heating current supply means 16 for letting flow a preset current in the filament 3 of the x-ray tube bulb 1 in the state where a tube voltage is not supplied.

Abstract: An x-ray generator wherein the tube current is kept constant independently of the drop in the cathode temperature after the radiation is switched on has a control circuit for the tube filament current in which a correction value that corresponds to the drop in the tube current given constant filament current during the radiation phase due to the drop in temperature of the cathode is superimposed on the rated value of the filament current at the beginning of radiation.

Abstract: The present invention, in one form, is a system for modulating x-ray tube current as a function of gantry angle and slice location in a computed tomography system. In one embodiment, a desired noise level for a final image is selected, and a desired minimum x-ray photon reading and a desired average x-ray photon reading are identified to produce an image in accordance with the desired noise level. During scanning, actual x-ray photon readings are used with the desired average x-ray photon reading and the desired minimum x-ray photon reading to generate an x-ray modulating factor. This modulating factor is then used to modulate the x-ray tube current.

Abstract: A method for controlling output of an x-ray source to optimize x-ray energy arriving at an associated x-ray receptor during linear tomographic examination. The method comprises the steps of selecting tomographic sweep parameters, predicting a set of x-ray source control parameters based, at least in part, upon the selected tomographic sweep parameters, and controlling x-ray source output in accordance with the set of x-ray source control parameters to optimize x-ray energy arriving at the associated x-ray receptor. Apparatus for controlling output of an x-ray source is also disclosed.

Abstract: The present invention, in one form, is an x-ray CT system that modulates x-ray tube current as a function of gantry angle and reconstruction algorithm weighting coefficients. View indexes are stored in a table, and during scanning, values are periodically read from this table to determine weighting coefficients. An algorithm is applied to the weighting coefficients to generate an x-ray tube modulating factor. This modulating factor is then applied to the x-ray tube current to generate modulated x-ray tube current.

Abstract: In a radiation emitting device, particularly in a radiation treatment device, the actual radiation delivered to an object via a radiation beam is adjusted dependent on the dimensions of an opening in a plate arrangement provided between a radiation source and an object so that the radiation output has a constant output factor over an irradiation field, regardless of the size of the opening. The output factor is defined as the ratio of the radiation output in air with a scatterer (such as shielding plates) in the beam path to the radiation output without the scatterer for a reference field.

Abstract: This invention aims at providing an X-ray apparatus having a stable X-ray output. Since the focus electrode of the X-ray tube of the X-ray apparatus according to this invention maintains a ground potential, the focus diameter of electrons bombarded against a target becomes constant. Hence, the X-ray output emerging from an exit window is stabilized. Since the potential ratio of a cathode to the target is always constant, the electric field distribution between the cathode and the target is stabilized, thereby stabilizing the X-ray output emerging from the exit window.

Abstract: A circuit arrangement for accurately measuring the x-ray tube current substantially eliminates measurement errors by taking the displacement current caused by the capacitance of the high-voltage cable into account in the measurement. A test voltage is taken across a precision resistor. Another voltage is tapped at a location which includes the high-voltage cable capacitance and is supplied to a status monitor which differentiates this voltage and generates a voltage signal which is superimposed on the test voltage for forming a current signal which accurately represents the x-ray tube current.

Abstract: An x-ray generator includes an x-ray tube voltage regulation system which automatically adapts to line impedance and fluctuations in the network voltage, so as to maintain the x-ray tube current at a maximum value. The x-ray tube current is set by the x-ray tube voltage, the x-ray tube current is regulated so that a maximally allowable line voltage drop is not upwardly exceeded. The x-ray tube current, consequently, always has its maximum value, given the prevailing circuit conditions, so that the tube power is also at a maximum value. The current is set so as to achieve a desired mAs product, which is in turn determined by the radiation dose which the operator desires.

Abstract: A sationary rotatable anode (42) of an x-ray tube (10) is electrically connected to a high speed starter (24). The starter (24) includes an inductive rotor (44) connected to the anode (42), a main stator winding (50) and an auxiliary stator winding (52). The rotor (44) is driven by a power drive circuit (26) which is part of the starter (24). A main capacitor (64) is placed in series with the main winding for reducing its inductance. An auxiliary capacitor (66) is placed in series with the auxiliary winding for maintaining a selective impedence. A control circuit (90) is included in the starter (24) to control the main current and auxiliary current so that as the rotation of the rotor (44) increases, the control circuit (90) lowers the frequency of the main current and the auxiliary current passing to the main and auxiliary windings.

Abstract: An X-ray inspection apparatus and method allow inspection of the contents of containers moving rapidly past an inspection station. The system includes an X-ray source pulsed by control logic, an image amplifier for converting an X-ray image of the container contents to a visible image and a solid-state camera for converting the visible image into video signals which are processed by a computer-controlled image processor. Clear images are produced of the contents of rapidly moving containers by pulsing the X-ray source. Control logic and a reject mechanism eject containers having foreign contaminants. Image illuminance stability is enhanced by feedback signals from the vision computer which operate a motorized camera lens.

Abstract: A power supply (C) for an x-ray tube filament (10) selectively functions either as a constant voltage source (12) or a constant current source (14). A control circuit (A) includes a voltage controller (56) for enabling the power supply to operate as the constant voltage source in a first time period t.sub.1 to t.sub.2 during which filament temperature (40) is increasing toward a preselected filament operating temperature (42). Once the filament temperature has substantially reached its operating temperature at a time t.sub.2, a timer (52) enables a current control (84) which causes the power supply to supply a constant current across the filament.

Abstract: A voltage control (22) controls the voltage applied between an anode (12) and a cathode filament (14) of an x-ray tube (10). A filament control (16) controls the amount of current fed through the filament. A voltage controlled oscillator (40) and counter (42) monitor the magnitude, if any, of a tube current (24) flowing between the cathode and the anode to generate x-rays (26). A microprocessor (50) calibrates the filament current such that the filament current value stored in a filament current look-up table (122) for each selectable tube voltage and tube current combination actually produces the selected tube current. The filament current is initialized (60) to a small current value and progressively incremented (66) until a commencement of the tube current (24) is monitored (64).

Abstract: A current detecting circuit for an X-ray tube is disclosed which includes a DC high voltage generating circuit connected across a filament and an anode of the X-ray tube and current detecting means connected in series in a filament circuit. The filament, which is at a high potential, receives a power from a secondary winding of an isolation transformer, which has sufficient dielectric strength to insulate a highest voltage generated by said DC high voltage generating circuit. A rectifier circuit is arranged to rectify a current fed from said secondary winding or another winding having same dielectric strength as that of said secondary winding, and said rectifier circuit supplies a power to a signal transmitting circuit. The signal transmitting circuit is energized, according to the current detected by said current detecting means, to transmit an output signal. The output signal is transmitted through electrically isolated transmission means to a signal receiving circuit, which is at a ground potential.

Abstract: A serial data communication device of a half-duplex communication system includes two communication units. One of the communication units has a counter for measuring a length of a remaining time during one sending/receiving period set for one-way data transmission (a period during one sending/receiving period W from the time when the communication unit receives all the send data from the other communication unit to the time to start data sending). A send frequency in data sending is determined to as a lower value practicable in the range in which no collision of the data occurs, depending on the length of the measured remaining time. The other communication unit is configured so as to receive the send data of one communication unit to extract the send frequency in synchronization with a serial clock signal having the same frequency as the send frequency and send the data.

Abstract: The invention concerns an X-ray tomograph device.This device makes it possible to obtain the image (1) of a plane cutting (2) of an object (3). In particular, it comprises an X-ray source (4) which supplies high energy pulses which traverse the object. At least one measurement detector small bar (10) receives the attenuated energy pulses which have traversed the object. A display and processing means connected to the detectors supplies the image of the cutting. These processing means include amplifier-integrator circuits (13) connected to the detectors (10) and to a computer (15) controlling the integration period of the detection pulses suplied by the detectors (10). The computer corrects the value of the amplitude of each detection pulse by talking account of an intermediate integration value so as to take account of the drag of each pulse and the stray current of each detector.

Abstract: The brightness of an X-ray video image during fluorography is maintained at a substantially constant level by a control circuit which varies the X-ray dose in relation to changes in the average brightness of the X-ray image. As the X-ray system approaches the limits of its imaging capability, varying the X-ray dose alone may not yield the desired brightness level. At this point, the gain applied to the video signal is increased to improve the brightness. A linear brightness taper function is used such that, as the level of video gain required to maintain constant brightness increases, the actual video gain increases by a smaller proportional amount. This function results in the brightness of the video image decreasing somewhat as the video gain is required to provide a greater degree of brightness compensation.

Abstract: The quality of x-ray images is significantly enhanced by adjusting the x-ray system operating parameters in real time during acquisition of x-ray data to take information about the part into account adaptively. X-ray energy, x-ray flux, and integration time can all by varied independently and in combination to improve the signal to noise ratio in the image. The x-ray data from a previous subsection of the image is processed to determine optimum system operating parameters for a next image subsection. x-ray tube voltage is adjusted to change x-ray energy and keep .alpha.L close to 2 over all image subsections. X-ray tube current is adjusted to change x-ray flux and data acquisition integration time is adjusted to keep the signal to noise ratio within limits.

Abstract: A filament current regulator for an X-ray generator includes a circuit which compares the actual X-ray tube filament current to a predefined filament current reference value. Another circuit is included which compares the actual X-ray tube excitation voltage, applied across the anode and to cathode of the tube, to a predefined reference voltage value. The regulator adjusts the filament current during a first time interval of an exposure based on only the filament current comparison, and during the remainder of the exposure based substantially on the excitation voltage comparison. The regulator apparatus also integrates the difference between the actual filament current and the reference current value over a given interval during the exposure. The integrated result is employed by the regulator to redefine the filament current reference value.

Abstract: The tube current in an X-ray tube is controlled by a closed loop control circuit in which a tube current feedback signal is used to control X-ray tube filament current. The gain of the feedback loop is maintained substantially constant over a wide range of tube currents by inserting a signal proportional to the reciprocal of the tube current command.

Abstract: A pre-ignition type X-ray apparatus including a mode changeover switch which changes a pre-heat mode to an X-ray irradiation mode and vice versa, a tube current control circuit for feedback control of the X-ray tube's filament heating current to a target value, and pre-heat control circuit for controlling the filament heating current in the pre-heat mode to a target value lower than the target value in the X-ray irradiation mode. The pre-heat control circuit includes a differential amplifier which amplifies the difference between the detected voltage corresponding to a source voltage and the reference voltage determining the lower target value, so that the control signal is outputted from the differential amplifier.

Abstract: The invention pertains to a current-supplying device used to supply heating current to a filment of an X-ray tube. The current-supplying device comprises a current inverter delivering current to a load circuit in which there is an oscillating circuit, the impedance of which is made to vary.

Abstract: In a circuit arrangement for producing high voltages by means of a voltage multiplier with rectifiers and capacitors and fed from an alternating current source in which circuit arrangement, a low amplitude voltage lying at the high voltage level is produced by the ripple voltage across one or more of the component parts of the voltage multiplier, the average potential of which component part (s) does not differ substantially from the high voltage. In the case of an X-ray tube high voltage supply the total filament circuit may be approximately on the high cathode voltage and no severe requirements for insulation need to be fulfilled. The ripple voltage may be used to produce other small amplitude voltages lying at a high voltage level.

Abstract: Between scans, a stand-by control (40) causes a filament current power supply (44) to supply a low level of power to a tube filament (46). When x-rays are to be generated, a non-linear digital to analog converter (50) supplies a filament current control signal which is estimated to provide a selected tube current. A space charge compensation circuit adds an offset to the selected filament signal to compensate for the selected voltage at which the tube is to be operated. A current boost circuit (70) adds an incremental current boost (26) of a magnitude in accordance with a function of the difference between the actual filament temperature and the normal operating temperature in order to bring the filament up to operating temperature more quickly. A feedback loop (90 to 98) adjusts the selected filament current signal in accordance with any difference between the selected tube current and the actual tube current.

Abstract: A high DC voltage generator for an X-ray tube includes a low voltage rectifier for rectifying a low AC input voltage to produce a low DC voltage, a DC-to-DC converter for converting the low DC voltage into a high DC voltage for the X-ray tube, and a controller for controlling transition characteristics of turning-on and off the X-ray tube. The controller shortens a rising time period of the high DC voltage until a rating anode voltage is applied to the X-ray tube after turn-on operation.

Abstract: An X-ray examination system comprising an X-ray generator, an image intensifier tube connected to an output optical path and an X-ray exposure control arrangement which measures the light image intensity LI at the output of the image intensifier during fluoroscopy, and from the relationshipI.sub.EXP1 =(LA.times.I.sub.FL)/LI.times.T.sub.EXP),derives the exposure value I.sub.EXP1 of the switch-on tube current required to provide a desired exposure density during subsequent fluorography with a tube voltage V.sub.FL and exposure time T.sub.EXP, and wherein LA is a predetermined constant.

Abstract: Disclosed is an inverter type X-ray apparatus comprising a DC-DC converter for converting a DC voltage into a different DC voltage, an inverter for inverting an output voltage of the DC-DC converter into an AC voltage, a high voltage transformer for transforming an output voltage of the inverter into a higher voltage, a rectifier for converting an AC output voltage of the transformer into a DC voltage, and an X-ray tube to which an output voltage of the rectifier is applied. In the apparatus, the DC-DC converter includes a reactor, a switching element and a capacitor which are interconnected so that the DC-DC converter can generate an output voltage higher or lower than an input voltage.

Abstract: A voltage signal proportional to the brightness of an x-ray image is derived. In a mA loop the ratio of a reference voltage to brightness is determined. If the brightness ratio does not equal 1 it causes the x-ray tube current controller to adjust current (mA) to eliminate the error. A command proportionate to the ratio is stored until the next image frame. In a kV loop a ratio of the last mA command and a set limit for mA is taken. This error ratio is multiplied by the brightness ratio to provide a kV control ratio indicative of how much of the brightness error the kV loop is obliged to correct. The kV control ratio is corrected for nonlinearity between kV change and brightness change and the resulting command is used to adjust the kV applied to the x-ray tube anode.

Abstract: A method of determining the optimum values of voltage and current for operation of an X-ray source by choosing a point of intersection at the lowest voltage value of a curve representing an operating range limitation function of the X-ray source with a curve representing a current-voltage function that passes through a desired operating current value that is determined by means of one or more exposure measurements.

Abstract: Anode life in an x-ray tube is extended by applying a reduced power density to the anode to afford controlled heating of the anode to a predetermined ductile temperature prior to operating the tube at full power. Controlled heating of the anode is accomplished by defocusing the electron beam for a period of time sufficient to enable the anode to reach the desired temperature. The electron beam source of the tube may also be controlled during heating of the anode so as to supply a reduced beam current.