Abstract: Method of improved detection of elements of interest by means of a detection system in a digital radiographic image of an object, acquired on an acquisition chain, comprising a first calibration phase in which the performances of the detection system are established. For such purpose, a calibration curve with several dimensions is determined by means of a mathematical model of the acquisition chain and object, in order to express a false positive probability as a function of a set of parameters corresponding to the acquisition chain and object. In the course of a second phase of use, a false positive probability value is determined for each pixel of the image. One then selects among the pixels of the digital radiographic image acquired those whose probability value obtained satisfies a predetermined criterion.

Abstract: The invention relates to a method and a device for reading out radiation image information stored on an image medium (12). A scanning unit (10) has a laser (16) for scanning the image medium (12) with a readout light beam (22). The read/processing device (14) functions with two channels so that the luminescent light emitted by the image medium (12) during scanning and also the reflected read-out light are synchronously detected, evaluated and correlated. The digital luminescent light image values are corrected according to the digital reflection light values in order to better obtain the radiation image information.

Abstract: Stimulating rays produced by a line light source are linearly irradiated onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, and light emitted from the linear area of the sheet upon stimulation is photoelectrically converted by a line sensor. Outputs of several pixel regions of the line sensor, which are adjacent to one another along the length direction of the linear area of the sheet and have widths taken in the length direction of the linear area of the sheet such that a sum of the widths is equal to the width of one pixel in a final image, are added together in order to constitute an image signal component representing one pixel in the final image.

Abstract: A stimulable phosphor sheet, on which radiation image information has been stored, is exposed to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. Light, which is emitted from opposite surfaces of the stimulable phosphor sheet when the stimulable phosphor sheet is exposed to the stimulating rays, is detected, and two original image signals representing the radiation image information are acquired. A read-out sensitivity and/or a read-out gain with respect to at least either one surface side of the stimulable phosphor sheet at the time of the image signal acquisition is controlled in accordance with specifications of the stimulable phosphor sheet.

Abstract: Disclosed herein is a method of obtaining an image signal, comprising the steps of preparing an image recording sheet having a stimulable phosphor layer which emits photostimulated luminescent light in a quantity corresponding to stored energy when irradiated with stimulating light, scanning the image recording sheet in horizontal and vertical scanning directions with the stimulating light, and obtaining the image signal by detecting the photostimulated luminescent light emitted by the scanning, with a solid-state image detector having a photoconductor. The signal, output from the solid-state image detector when scanning a non-image region other than an image recording region on the image recording sheet with the stimulating light, is detected as a correction signal. A non-image component, contained in a signal output from the solid-state image detector when scanning the image recording region with the stimulating light, is suppressed with the correction signal.

Abstract: A radiation image read-out apparatus including a lens array and a line sensor for reading an image recorded on a stimulable phosphor sheet provides a read-out image of high quality which is free from a spurious pattern due to non-aperture regions of the lens array. A first memory stores an image signal representing the image recorded on the stimulable phosphor sheet. Spurious pattern signal calculating means calculates a spurious pattern signal based on positions of the non-aperture regions on the lens array. The spurious pattern signal is stored in a second memory. Image modification means reads the image signal and the spurious pattern signal from the first and second memories to calculate a processed image signal free from any spurious pattern signal on a pixel-by-pixel basis. The spurious pattern signal may instead be obtained by causing the apparatus to read a uniform radiation image recorded on the stimulable phosphor sheet.

Abstract: An image signal representing radiation image information on an object stored on a stimulable phosphor sheet is read out by scanning the stimulable phosphor sheet with a stimulating light beam and photoelectrically detecting light emitted from the stimulable phosphor sheet upon stimulation thereof by a photodetector having a photoelectric surface. A variable transmittance medium whose transmittance to the light emitted from the stimulable phosphor sheet upon stimulation thereof is variable continuously or stepwise is inserted into the optical path of the light between the stimulable phosphor sheet and the photoelectric surface of the photodetector. The transmittance of the variable transmittance medium is changed according to the amount of light emitted from the stimulable phosphor sheet upon stimulation thereof so that the photoelectric surface is not saturated by an excessive amount of light impinging thereupon.

Abstract: Initial image data having a pixel size smaller than a pixel size of a final image are obtained by using line sensors arranged in a main scan direction and a vertical scan direction, and the final image becomes of high quality by processing the initial image data to prevent the image from becoming uneven. Integration processing means carries out a first conversion process to convert the initial image data comprising signals detected by the line sensors into data for pixels divided in the main scan direction. The integration processing means carries out a second conversion process in which, whenever the data are obtained for three consecutive pixels in the main scan direction, the data are added to become data for one pixel of the final image. The data for the final image are then subjected to an equalization process such as dark current correction carried out by a correction means.

Abstract: Two image signals representing radiation image information are acquired from opposite surfaces of a stimulable phosphor sheet, on which the radiation image information has been stored. Operation processing is performed on the two image signals in accordance with predetermined operation processing parameters, and an operation-processed image signal representing the radiation image information is obtained. A ratio between read-out sensitivities with respect to the opposite surface sides of the sheet and/or the predetermined operation processing parameters with respect to at least either one surface side of the sheet are controlled in accordance with read-out conditions employed at the time of the image signal acquisition.

Abstract: A radiation image data readout apparatus in which read out is performed so that a detected light quantity for each CCD element of each CCD sensor is set at a quantity below the saturation charge quantity of each CCD element, and the level of noise is reduced. The radiation energy stored on a readout-line of a stimulable phosphor sheet is estimated, and based on the estimated quantity of radiation energy, a controller sets the readout conditions, which are formed of the charge accumulation time of the readout line and the binning conditions, and readout is performed by a line sensor according to these conditions.

Abstract: Stimulating rays produced by a line light source are linearly irradiated onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, and light emitted from the linear area of the sheet upon stimulation is photoelectrically converted by a line sensor. Outputs of several pixel regions of the line sensor, which are adjacent to one another along the length direction of the linear area of the sheet and have widths taken in the length direction of the linear area of the sheet such that a sum of the widths is equal to the width of one pixel in a final image, are added together in order to constitute an image signal component representing one pixel in the final image.

Abstract: Stimulating rays produced by a line light source are linearly irradiated onto an area of a stimulable phosphor sheet, on which a radiation image has been stored. Light, which is emitted from the linear area of the sheet exposed to the linear stimulating rays, is received and photoelectrically converted by a line sensor. Outputs of the line sensor are corrected in accordance with variation in sensitivity among a plurality of pixel regions of the line sensor, which pixel regions are arrayed along the length direction of the linear area of the stimulable phosphor sheet.

Abstract: A method for processing electric signals of a radiographic image which are obtained by the steps of scanning a stimulating light beam on a stimulable phosphor sheet comprising a stimulating light-reflective or -absorbent grid and stimulable phosphor-containing microcells surrounded by the grid and having a radiographic image recorded therein in a direction along the grid and photoelectrically collecting in sequence stimulated emissions emitting from the microcells, is favorably performed by detecting a signal of a grid surrounding a microcell and a signal strength corresponding to the microcell surrounded by the grid; determining a correcting value for the detected signal strength; repeating the step of determining a correcting value for a signal strength in each microcell; and processing each signal strength detected in each microcell using each correcting value determined in each microcell, in consideration of a predetermined pixel size of the radiographic image, to obtain a corrected radiographic image dat

Abstract: Stimulating rays produced by a line light source are linearly irradiated onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, the stimulating rays causing the sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation. Light emitted from the exposed linear area of the sheet is received with a line sensor comprising photoelectric conversion devices arrayed along each of a length direction of the linear area of the stimulable phosphor sheet and a direction normal to the length direction. The sheet is moved with respect to the line light source and the line sensor and in a direction different from the length direction of the linear area of the sheet. Operation processing is performed on outputs of the photoelectric conversion devices, which outputs have been obtained at respective positions of movement and correspond to an identical site on the sheet.

Abstract: Disclosed herein is a method of obtaining an image signal, comprising the steps of preparing an image recording sheet having a stimulable phosphor layer which emits photostimulated luminescent light in a quantity corresponding to stored energy when irradiated with stimulating light, scanning the image recording sheet in horizontal and vertical scanning directions with the stimulating light, and obtaining the image signal by detecting the photostimulated luminescent light emitted by the scanning, with a solid-state image detector having a photoconductor. The signal, output from the solid-state image detector when scanning a non-image region other than an image recording region on the image recording sheet with the stimulating light, is detected as a correction signal. A non-image component, contained in a signal output from the solid-state image detector when scanning the image recording region with the stimulating light, is suppressed with the correction signal.

Abstract: In a two-side radiation image reading method wherein a stimulable phosphor sheet storing a radiation image is scanned by stimulating rays and light emitted from the front and back sides of the sheet is photoelectrically detected by photoelectric reading means separately located on the front and back sides of the sheet to obtain two image signals representing the radiation image to be subjected to addition processing or the like for obtaining a final image, shading correction data and/or fading correction data are obtained in advance and shading correction and/or fading correction is carried out on the image signals by using the correction data having been obtained. While an area equivalent to one side of the stimulable phosphor sheet (whose number of main scan lines is 4320) is being scanned, reading of the sheet is switched between the front and back sides and sensitivity of photoelectric reading means is also changed (to standard, semi-high, and high).

Abstract: An apparatus for reading out a storage luminophore plate has a holder for the storage luminophore plate as well as for a detector line, and a device for setting the spacing between the storage luminophore plate and the detector line such that this spacing is controlled or regulated to be substantially constant with reference to the storage luminophore plate, at least over the region of the detector line.

Abstract: Stimulating rays produced by a line light source are linearly irradiated onto an area of a stimulable phosphor sheet, on which a radiation image-has been stored, the stimulating rays causing the sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation. Light emitted from the exposed linear area of the sheet is received with a line sensor comprising photoelectric conversion devices arrayed along each of a length direction of the linear area of the stimulable phosphor sheet and a direction normal to the length direction. The sheet is moved with respect to the line light source and the line sensor and in a direction different from the length direction of the linear area of the sheet. Operation processing is performed on outputs of the photoelectric conversion devices, which outputs have been obtained at respective positions of movement and correspond to an identical site on the sheet.

Abstract: Stimulating rays produced by a line light source are linearly irradiated onto an area of a stimulable phosphor sheet, on which a radiation image-has been stored, the stimulating rays causing the sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation. Light emitted from the exposed linear area of the sheet is received with a line sensor comprising photoelectric conversion devices arrayed along each of a length direction of the linear area of the stimulable phosphor sheet and a direction normal to the length direction. The sheet is moved with respect to the line light source and the line sensor and in a direction different from the length direction of the linear area of the sheet. Operation processing is performed on outputs of the photoelectric conversion devices, which outputs have been obtained at respective positions of movement and correspond to an identical site on the sheet.

Abstract: A stimulable phosphor sheet, on which a radiation image has been stored, is scanned with stimulating rays in a main scanning direction and moved in a sub-scanning direction, which is approximately normal to the main scanning direction. A read-out device photoelectrically detects the light, which is emitted by the stimulable phosphor sheet when the stimulable phosphor sheet is scanned with the stimulating rays in the main scanning direction, to obtain an image signal representing the radiation image. A light guiding mirror for reflecting the emitted light toward the read-out device is located to extend in the main scanning direction at a position in the vicinity of a position on the stimulable phosphor sheet, which position is scanned with the stimulating rays in the main scanning direction. The light guiding mirror is supported by a support member, which is formed from a metallic material and is electrically isolated from a ground, or which is formed from an electrical insulating material.

Abstract: A stimulable phosphor sheet, on which a radiation image has been stored, is exposed to stimulating rays. Light emitted from the front surface of the stimulable phosphor sheet and light emitted from the back surface are detected with two photoelectric read-out devices located on the opposite surface sides of the sheet. Two image signals having thus been obtained are added in predetermined addition ratios w1 and w2.

Abstract: A first image signal representing a radiation image of an object is obtained by exposing a stimulable phosphor sheet, on which the radiation image has been stored, to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation, the emitted light being detected. A second image signal representing the radiation image is thereafter obtained by again exposing the stimulable phosphor sheet to stimulating rays, the light emitted by the stimulable phosphor sheet being detected. Read-out conditions, under which the second image signal is to be obtained, and/or image processing conditions, under which the second image signal having been obtained is to be image processed, are adjusted on the basis of the first image signal. A storage device stores information representing a standard pattern of radiation images.

Abstract: A method of reading a radiographic image on a stimulable phosphor sheet includes a step of obtaining correction data in which a spatial frequency processing is conducted so as to reduce a predetermined spatial frequency component of an image information which is irradiated with radiation without placing a subject. The predetermined spatial frequency component corresponds to an irregularity with poor reproducibility in terms of its position on the image information. The correction data is made so as to eliminate an irregularity which is reproducible of its position on the image information.

Abstract: An image reading apparatus which includes a primary scanner for scanning an original X-ray image obtained using a grid and recorded on a recording medium with light in a primary scanning direction. A clock signal generator generates clock signals having a frequency N times as high as a frequency of pixel clock signals, wherein the pixel clock signals correspond to a desired pixel size, and wherein N is a positive integer. A converter converts a light beam from the recording medium into electric signals by a scanning operation of the primary scanner, and converts the electric signals into digital signals based on the clock signals. A low pass filter is provided which has at least one set of filter characteristics having a cut-off frequency between 1/3 and 2/3 of the frequency of the pixel clock signals for filtering the digital signals converted by the converter.

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: Method of correcting a radiation image for defects in the recording member. Defects in a member for recording a radiation image are corrected by generating a calibration matrix comprising for each pixel a correction value and by applying corresponding elements of the calibration matrix to the pixels of a recorded image. The values of the calibration matrix represent in each pixel the deviation of the value that is effectively obtained in a pixel when the recording member is subjected to a flat field exposure and the value that would be expected in the pixel. Different methods are described for determining the expected value in a pixel. Further, an overlay image is generated wherein local defects are visualised.

Abstract: An image processing apparatus includes a histogram producing section for producing a histogram of density signal levels of pixels constituting the image data, a reference density signal level detecting section for detecting from the histogram a density signal level processed by the maximum number of the pixels in a range excluding the maximum value and the minimum value of the density signal levels, a density signal level conversion range determining section for successively comparing the number of the pixels of each density signal level with a threshold value from the density signal level processed by the maximum number of the pixels to lower density signal levels, thereby determining a density signal level lower limit value of density signal levels to be converted and successively comparing the number of the pixels of each density signal level with a threshold value from the maximum value of the density signal level to lower density signal levels, thereby determining a density signal level upper limit value

Abstract: An irradiation field region extracting apparatus for extracting an irradiation field region from a given radiation image. According to a first embodiment, image data corresponding to the radiation image is rotationally moved around a predetermined rotational center of the image data, with the image data having rectangular coordinates set thereon. A boundary line is extracted between the irradiation field region, where the radiation image is exposed, and an irradiation field stop region, where no radiation image is exposed, according to the image data rotationally moved by the rotational movement means. A parallel condition of the boundary line is detected wherein the boundary line is parallel to an axis of the image data, and rotation information data is generated which indicate an angle of a rotational movement of the boundary line from an original location to a location of the parallel condition and a distance between the predetermined rotational center and a given point on the boundary line.

Abstract: A stimulable phosphor sheet, on which a radiation image of an object has been stored, is exposed to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The emitted light is detected by a photoelectric read-out device, and an image signal representing the radiation image is thereby obtained. Threshold value processing is carried out in accordance with the obtained image signal, and a prospective abnormal pattern is thereby detected from the radiation image. A predetermined threshold value, which is used in the threshold value processing for detecting the prospective abnormal pattern, is set to be a small value as the amount of change in the image signal corresponding to the region in the vicinity of the prospective abnormal pattern becomes large.

Abstract: A stimulable phosphor sheet, on which a radiation image has been stored, is exposed to stimulating rays, which cause it to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The light, which is emitted from the front surface of the stimulable phosphor sheet, and the light, which is emitted from the back surface of the stimulable phosphor sheet, are respectively detected. An image readout from the front surface of the stimulable phosphor sheet and an image readout from the back surface of the stimulable phosphor sheet are thus carried out independently of each other, two image signals being thereby obtained. An abnormal state in the image readout from each of the front and back surfaces of the stimulable phosphor sheet is detected.

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: A calibration technique for a storage phosphor reader which calibrates the storage phosphor reader to the exposure value of the x-ray source measured at the time that the storage phosphor to be read is exposed.

Abstract: A method of automatically adjusting the tone scale adjustment for digital radiographic images. The method includes the steps of providing an input digital radiographic image; estimating the image noise as a function of code value of the image; determining the range of code values in the input image; determining which way the input image should be processed; determining a bounding box which contains the region of interest of the input image; computing the image activity histogram of the input image; determining four points from the image activity histogram; constructing the tone-scale curve for the input image; and mapping the input image through the tone-scale curve to produce an output image with good tone scale.

Abstract: A stimulable phosphor sheet, on which a radiation image has been stored, is exposed to stimulating rays, which cause it to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The light, which is emitted from the front surface of the stimulable phosphor sheet, and the light, which is emitted from the back surface of the stimulable phosphor sheet, are detected respectively with two photoelectric read-out devices, and two image signals are thereby obtained. The two image signals are added to each other in a predetermined addition ratio.

Abstract: In a method for detecting a prospective abnormal pattern, a stimulable phosphor sheet, on which a radiation image of an object has been stored, is exposed to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The emitted light is detected by a photoelectric read-out device, and an image signal representing the radiation image is thereby obtained. A prospective abnormal pattern is detected from the radiation image in accordance with the obtained image signal. During the detection of the prospective abnormal pattern, in accordance with the image signal, calculations are made to find a normalized read-out sensitivity and a normalized latitude, which are equivalent to read-out conditions appropriate for obtaining a visible image reproduced from the radiation image.

Abstract: A calibration technique for a storage phosphor reader which accomplishes the following; a) finds the leading edge of the storage phosphor being read by the reader; b) finds the front and rear edges of the storage phosphor in order to adjust the length of the line scan to the dimension of the storage phosphor in the line scan direction; c) verifies that the photodetectors of the reader are functioning; d) adjusts each photodetector signal channel to the appropriate gain; and e) generates a correction signal to correct nonuniformities of the photodetector signal output.

Abstract: A first image signal representing a Magen radiation image is obtained by exposing a stimulable phosphor sheet, on which the Magen radiation image has been stored in a subdivision pattern composed of at least a single subdivision, to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation, the emitted light being detected. The kind of the subdivision pattern of the Magen image is discriminated on the basis of the first image signal or information given by an image recording system, which carries out an image recording operation. The kind of an image recording pattern of the Magen image is determined from the kind of the subdivision pattern, which has been discriminated.

Abstract: A radiation image storage panel, on which a radiation image has been stored, is exposed to stimulating rays, which cause it to emit light in proportion to the amount of energy stored thereon during its exposure to the radiation. The emitted light is photoelectrically detected on the front surface side of the radiation image storage panel, which is the stimulating ray incidence side, and on the back surface side, two image signals being thereby obtained. The image signal components of the two image signals are added to each other, which represent corresponding picture elements on the front and back surfaces of the radiation image storage panel, an addition signal being thereby obtained.

Abstract: In a radiation image read-out apparatus, a stimulable phosphor sheet, on which a radiation image has been stored, is exposed to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The emitted light is detected and photoelectrically converted by a photodetector, and an image signal representing the radiation image is thereby generated by the photodetector. Information corresponding to the amount of energy stored on the stimulable phosphor sheet during its exposure to radiation is inputted from a stored energy amount input device.

Abstract: An automated method for analyzing the photometric calibration and image quality performance characteristics of a high resolution storage phosphor reader. A custom fabricated, lead mask test target is secured to a storage phosphor and exposed using a standard medical x-ray source. A storage phosphor reader, to be calibrated, reads the exposed storage phosphor to produce a digital x-ray image. The digital x-ray image is analyzed by means of a computer algorithm which presents analytic results in text and graphical form to isolate reader problems and to quantify calibration status of the reader.

Abstract: Radiation images of an object constituted of tissues exhibiting different levels of radiation absorptivity are formed with two kinds of radiation having different energy levels. A first original image signal SO1 and a second original image signal SO2 representing the radiation images are detected. A superposition image signal is generated with a weighted addition expressed asS=(N2.sup.2 /(N1.sup.2 +N2.sup.2)).times.SO1+(N1.sup.2 /(N1.sup.2 +N2.sup.2)).times.SO2wherein N1 and N2 respectively represent noise contained in the first and second original image signals. A first image signal representing a first image primarily composed of patterns of first tissues of the object is generated by subtracting the first and second original image signals from each other. A first smoothed image signal representing a first smoothed image, in which noise of the first image has been reduced or eliminated, is generated by smoothing the first image signal.

Abstract: Storage phosphor imaging system includes a source of stimulating light, a scanner for scanning a storage phosphor with a latent x-ray image with said stimulating light in a raster pattern to produce an emitted light x-ray image and a photodetector for converting the emitted light x-ray image into an x-ray image signal. The storage phosphor has associated with it a first bar code pattern of alternating bars and spaces for identifying the storage phosphor and a second bar code pattern of contiguous reflective/nonreflective cells for identifying storage phosphor exposure speed and storage phosphor size parameters. A first scanning bar code reader and a second bar code reader including a number of contiguous light emitter and photodetector assemblies, read the first and second bar code patterns, respectively, to produce signals used in identifying, reading and processing the storage phosphor and image signal.

Abstract: A plurality of original image signals which represent a plurality of radiation images are obtained by exposing recording media to radiations with different energy levels which have passed through an object constituted of a plurality of tissues exhibiting different levels of radiation absorptivity with respect to radiations with different energy levels. An extracted image signal representing an extracted image of a predetermined tissue in the object is obtained on the basis of the original image signals. A processed image signal representing a processed image is obtained by calculating a processed image signal component S' corresponding to a predetermined picture element in the extracted image according to formula S'=Sorg+.beta..multidot.

Abstract: A plurality of radiation images of an object is recorded on a plurality of recording sheets by exposing the recording sheets to radiations which have different energy distributions and have passed through the object. The plurality of radiation images are read out and a plurality of image signals which respectively represent the plurality of radiation images are obtained. A correction formula according to which correction of one or more of the image signals for superposing the radiation images represented by the respective image signals one on another is effected for each picture element is obtained and subtraction processing is effected for each picture element while the aforesaid correction is effected for each picture element according to the correction formula.In other words, the steps of correction, superposition and subtraction are performed consecutively and on a picture element by picture element basis.