Abstract: A neural network prediction has been provided for predicting radiation exposure and/or Air-Kerma at a predefined arbitrary distance during an x-ray exposure; and for predicting radiation exposure and/or Air-Kerma area product for a radiographic x-ray exposure. The Air-Kerma levels are predicted directly from the x-ray exposure parameters. The method or model is provided to predict the radiation exposure or Air-Kerma for an arbitrary radiographic x-ray exposure by providing input variables to identify the spectral characteristics of the x-ray beam, providing a neural net which has been trained to calculate the exposure or Air-Kerma value, and by scaling the neural net output by the calibrated tube efficiency, and the actual current through the x-ray tube and the duration of the exposure. The prediction for exposure/Air-Kerma further applies the actual source-to-object distance, and the prediction for exposure/Air-Kerma area product further applies the actual imaged field area at a source-to-image distance.

Abstract: An exposure management and control system and method for x-ray technique selection is provided. Optimal x-ray technique, which affects image quality, can be accurately predetermined to use for any application. A patient model is combined with a closed loop brightness control, using a parameter that does not affect image quality. This is used to create a control system that operates as a knowledge based control system. The x-ray system brightness control system comprises a first and second regulator. The first regulator is an image quality, or brightness, regulator. The brightness regulator can have multiple functions, such as peak mA control, power limiter, skin dose limiter, and an override function. The second regulator is a dose error regulator. The second regulator is independent of the first regulator, and cooperates with the first regulator to provide x-ray technique optimization independent of brightness control.

Abstract: A model-based optimization is used to determine x-ray techniques for optimal image quality performance. The first step for achieving model-based optimization is to determine optimized techniques for a fixed spectral filter and focal spot to define a basic trajectory. The spectral filter and focal spot versus patient size are then optimized. The determined optimized techniques and the optimized spectral filter and focal spot versus patient size are used to create a functional trajectory which includes a Basic Trajectory Selector Table (indicating optimized spectral filter/focal spot) and the associated basic trajectories.

Abstract: An x-ray imaging system includes a source of x-rays, a video camera which produces an image signal formed by x-ray attenuation values, and image signal processor and a video monitor for displaying the x-ray image. The system also has an automatic image control that includes a peak detector, an average brightness detector and a transfer function generator for the image processor. The peak detector receives the image signal and produces a video gain control signal for controlling the video camera in response to a comparison of a peak level of the image signal to a peak reference level. The average the brightness detector employs the image signal to produce a feedback signal which controls by the source of x-rays. The transfer function generator produces a histogram of intensity levels in the image signal which histogram forms a look-up table that is used by the image processor to transform the image signal into the adjusted image signal for display.

Abstract: A hand-held device produces an omnidirectional beam of infra-red light which can be aimed by the user. A plurality of detectors positioned in a rectangular array adjacent a video monitor and each detector produces an electrical signal that varies as a function of the light intensity impinging thereon. A circuit compares the signals from the detectors to determine coordinates of a position on the monitor at which to place a cursor. A linear transfer function is applied to the detector signals before determining the coordinates. The coordinates are processed by a seventh order recursive digital filter and the resultant position must be a minimum distance from the present position before the cursor is relocated. By varying the direction of the light beam the cursor position can be changed. When the cursor is at the position desired by the user, the hand-held device is activated to produce a different light beam.

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: An X-ray tube is movable between a minimum distance from an image receptor and a maximum distance. Signals are generated representative of the X-ray tube focal spot-to-image distance (SID), the peak kilovoltage (kVp) that is to be applied to the X-ray tube anode during a fluorographic exposure and the desired brightness of the X-ray image. The signals are processed in a manner that results in a control signal being developed that adjusts the X-ray tube filament current in a way that produces an X-ray tube current (mA) during the exposure which results in a constant limited X-ray dose rate at the X-ray beam entrance plane of a patient at any permissible kVp and SID setting and assures that the dose rate limit will not be exceeded at minimum permissible SID regardless of the selected kVp.

Abstract: Analog video signals representative of an X-ray image are gated to a first integrator during times in each horizontal line scan in a raster field when a window signal exists and the video signal amplitude is also above a threshold reference level for the integrator to produce a signal representative of the average brightness of the image in areas that are not excluded by their video signal being below threshold level. A second integrator integrates a constant reference voltage signal only during the time that the video signal is being integrated. Since the video scanning rate is constant, the simultaneously produced second integrator signal corresponds to the total continuous or discontinuous area or areas over which the video signal is integrated. The integrated signal representing average image brightness is divided by the signal representing area to yield a signal representing brightness per unit area.

Abstract: An automatic x-ray exposure time control wherein compensation curves representative of plots and reference signal voltages versus integrated x-ray dose signals can be reconfigured to account for the variable effects on x-ray film density resulting from the specific image receptor, collimator field area, x-ray intensity sensor and density factor used in any x-ray exposure technique over a range of operator-selected x-ray tube kilovoltage (kV) and current (mA). Data for a relatively small number of basic compensation curves are obtained and stored in ROMs. These curves are plots of exposure times versus integrated x-ray dose signals which resulted in producing a constant predetermined and desired film density for whatever amount of x-ray attenuating material is in the x-ray beam. Each basic curve is obtained with the x-ray tube operating at a particular kV and mA.