Abstract: The contrast of an image is enhanced by converting the digital signal representation of the image according to a conversion function that is derived from a parameterised conversion function q(x) by giving specific values to the parameters of the function. Specific values for parameters that depend on the examination type to which the image relates are exclusively derived from the digital signal representation itself. No input of examination type dependent parameters is required.

Abstract: A method of reducing noise in an image by decomposing the digital signal representation of the image into a sequence of detail images representing detail at successive scales and a residual image and modulating pixels of at least some of the detail images by applying modulating coefficients. The modulating coefficients are deduced from a single contrast-to-noise ratio image which represents the local contrast-to-noise ratio in each pixel at a predefined scale.

Abstract: A method for processing a radiographic image in a digital radiographic system. The image is processed to attenuate light transmitted by a diagnostically irrelevant area when a hard copy is viewed on a console screen or when the image is displayed. Information within the diagnostically irrelevant area is retained notwithstanding the processing attenuation.

Abstract: A method for verifying the modulation depth of a digital radiographic read out system. The system reads a radiation image by line-wise scanning a photostimulable phosphor screen that has been exposed to the radiation image. The radiation image includes an image of a phantom that has at least one x-ray opaque grating with parallel lines and a stepwise evolving spatial frequency. SWR values are determined by analyzing the x-ray image of the phantom. These SWR values are compared with acceptance values and the results of the comparison are used to adjust the scanning read out system.

Abstract: A method for quantitative verification of line-wise scanning geometry in a digital radiographic read out system. An x-ray transparent phantom substrate with an embedded ruler having a number of equidistant parallel strips that are opaque on top of a photostimulable phosphor screen so that the ruler is parallel with the direction of line-wise scanning. After x-ray exposure and scanning, the position in the scanning direction of the center of each ruler strip is computed. At least one of the following parameters is determined: average pixel sampling distance, geometric distortion value, and total scanned width.

Abstract: A contrast enhancing processing method is disclosed that is based on a transformation of an original image into a multiresolution edge representation based on a wavelet transform. The multiresolution edge representation is modified and subsequently subjected to a reconstruction procedure. Different embodiments are disclosed that are based on different forms of the multiresolution edge representation.

Abstract: A radiographic image read out system having on-line performance verification. A number of parameters to be used in a test program are stored together with (a) limiting value(s) for (a) characteristic value(s) resulting from application of the test program. An image signal of a phantom is processed according to the test program to determine at least one characteristic value. At least one limiting value for each determined characteristic value is retrieved from storage and a hard copy of the image of the phantom along with the at least one characteristic value in relation to the limiting value(s) is produced.

Abstract: A method for monitoring the sensitivity of a system that reads a radiation image or an irradiated object with the radiation image being stored in a photostimulable phosphor screen. The method employs the steps of scanning the screen with stimulating irradiation, detecting the light emitted upon stimulation, compressing the electric representation through square root amplification, and then digitizing the compressed electric representation. For a sensitivity class that was set when the radiation image was generated a corresponding expected noise variance value .sigma..sub.e.sup.2 is retrieved from a predefined table and the ratio .sigma..sub.y.sup.2 /.sigma..sub.e.sup.2 is calculated and thresholded. A warning is generated when the ratio exceeds a threshold value T.sub.+ or when the ratio is smaller than a threshold value T.

Abstract: A system and method for reading and processing a radiation image that has been stored in a photostimulable phosphor screen. An identification station, a read out and processing station and an off-line workstation are provided. A customized and configurated parameter set is generated that links with an examination type a set of parameters. This parameter set is used when controlling operation of each individual station of the system.

Abstract: Method and apparatus for displaying images obtained by reading out stimulable phosphor screens wherein radiation images are stored. A mosaic type image is composed by means of a plurality of read-out images and said mosaic type image is displayed on a preview monitor or on one of a plurality of preview monitors.

Abstract: The disclosed methods for generating scatter-compensated radiation image are based on one irradiating shot of the object. By comparing the detected signal under a partially transparent body (ea. disk or strip), positioned between the x-ray source and the object being imaged, with the signal in the image near the border of the shadow of the partially transparent body, the radiation scatter signal in the location of the body is calculated. In case of a polychromatic source, calibration with two known materials allows accurate calculation of the radiation scatter. The partially transparent bodies are positioned at several locations in between object and source and, by means of interpolation technique, the radiation scatter in every location of interest can be calculated. The radiation scatter image is subtracted from the original image of the object.

Abstract: A method and an apparatus are disclosed for controlling the amount of irradiation effectively emitted by a source of penetrating radiation in a system wherein radiation emitted by said source and attenuated by an object is stored in a photostimulable phosphor screen. An indication of the effectively emitted radiation amount is obtained by means of a difference of a specific signal value and a predetermined signal value.

Abstract: A phantom for determining attenuation by a combination of materials of polychromatic X-rays comprises a number of tubes that can be positioned in between a source emitting said X-rays and an X-ray detector. The tubes are held in a position so that they are directed towards the position of a source of radiation. In each tube a combination of thicknesses of said materials is provided.

Abstract: A noise reducing method and associated apparatus for use in a medical radiographic imaging system wherein an image represented by an array of pixels is processed and the processed image is recorded on a recording medium or visualized on a display monitor. The processing comprises the steps ofa) decomposing an original image into a sequence of detail images or into an array of coefficients representing detail strength at multiple resolution levels and a residual image,b) pixelwise attenuating the detail images or the coefficient arrays according to the locally estimated amount of relevant signal present and in accordance with an estimated noise level,c) reconstructing a processed image by accumulating detail obtained from the attenuated detail images or from the attenuated detail coefficients, and further adding the residual image.

Abstract: A method of determining a conversion of a digital image representation of a radiologic image into density values wherein the gradation curve of a conventional screen/film system is approximated.