Abstract: A method of ascertaining imaging quality in a computed radiography (CR) system includes providing a substrate having fluorescent test pattern disposed thereon. The substrate is disposed in place of the standard storage-phosphor screen and scanned as if reading out a storage screen. The detected signals form a read-out image which is then compared against the test pattern to judge image quality.
Abstract: An integrating optical collector with a diffusely reflective interior surface and with at least one wavelength selective absorptive filter located therein in a position that nearly bisects the interior of the collector. The filters are highly transmissive in a first wavelength band corresponding to an emission band of a storage phosphor, but highly absorptive in a second wavelength band corresponding to a stimulation band of the phosphor. The filter's wavelength selective properties and nearly bisecting position in the collector minimizes re-illumination of a phosphor at the stimulation wavelength, while permitting efficient radiation collection and detection at the emission wavelengths. A cylindrical collector with two parallel lengthwise slits permitting passage of the scan beam to the phosphor surface is preferred. Two filter plates on opposite sides of the slit may be used, which can either be parallel to each other and to the slits or oriented at an angle with respect to each other.
Abstract: A hollow light collector has an internal surface coated with a wavelength selective coating to absorb light energy within a predefined range of wavelengths and reflect all other light energy. In the preferred embodiment, the light collector is cylindrical in shape and includes an entrance aperture extending along the longitudinal axis of the collector. An exit aperture is disposed opposite to, and is coextensive with, the entrance aperture, defining a beam path therebetween to allow a scanning beam to traverse the chamber. A detector, such as a photomultiplier tube, is in optical communication with the chamber and is disposed off the beam path to detect light reflecting from the coating. In other embodiments, the chamber of the hollow collector may be spherical or ellipsoidal in shape.
Abstract: A system and method for performing a rapid, automatic, quantitative assessment of the image quality of a radiographic image is disclosed. The present invention utilizes a stepped calibration target made of differentially attenuating disks that is exposed to a beam of radiation simultaneously with the exposure of an object of examination. The recording medium is developed, if necessary, and the image of at least the calibration target is read, as with a laser scanner or a CCD. The optical density characteristics of the image of the calibration target are then analyzed with respect to reference optical density criteria associated with the type of recording medium used and indicative of an optimal signal pattern. If the optical density characteristics of the calibration target image meet the reference criteria, then an indication is made to show that the radiographic image has been approved as meeting the quality assurance threshold.
Abstract: A wideband amplifier which employs a plurality of cascaded logarithmic amplifier stages under the control of a digital signal processor which nulls offset voltages. In one aspect of the invention, the digital signal processor controls switches, one switch associated with each amplifier stage for determining an appropriate offset voltage and producing a counterbalancing signal. In another aspect of the invention the amplifier includes two potentiometers or variable signal devices which can set the overall input signal level and set the ratio of maximum to minimum of the input signal level, respectively, to desired levels. In a third aspect of the invention, a lookup table is associated with the digital signal processor for storing correction factors to be applied to digitized values in order to produce a final result which is corrected for variations in the amplifier characteristic from true logarithmic.
Abstract: A method for digital imaging employing a green light laser. The method comprises obtaining a digitized picture image, modulating a green light laser beam in accord with the digitized picture image, and directing the modulated laser beam onto film that is sensitive to green-blue light. The film is then developed to create a gray-scale image useful in radiography and other imaging fields.
Abstract: An x-ray cassette positioner for use with a plurality of x-ray cassettes. The cassette positioner includes first and second conveyors. The conveyors have a first endless cogbelt and a second endless cogbelt, respectively. The cogbelts are spaced apart. The cogbelts each have a plurality of outwardly extending shelves. The conveyors each have a pair of cogwheels, each pair of cogwheels receives a respective cogbelt. The cogbelts each have a utilization segment and a return segment. The shelves of the utilization segment of said first cogbelt face and are in vertical alignment with corresponding shelves of the utilization segment of the second cogbelt. The aligned shelves define a cassette read site and a plurality of cassette loading sites. A positive drive is operatively connected to both conveyors and drives the conveyors in unison to transfer cassettes loaded in the loading sites serially through the loading sites and the read site. A body encases the conveyors.
June 22, 1992
Date of Patent:
January 11, 1994
Eastman Kodak Company, Lumisys, Inc.
John C. Boutet, James F. Owen, John E. Becker, Gary Unruh
Abstract: A system and method for processing images viewed on radiographic film. Such images include mammograms, CAT scans, or other standard x-ray type images. The system includes a scanning laser film digitizer for reading the optical density of pixels in an original film image; a controller which analyzes the image data based on input film type and scanned optical density in order to compute an exposure correction factor which enhances the original image quality; and a laser film writer which creates a new copy of the original data in the improved form. The system is capable of writing several proportional non-overlapping images on a single sheet of film. This feature facilitates diagnostic evaluation of related subject matter such as multiple angle views of an injury, simultaneous views of right and left side mammograms, or several CAT scans on a single exposure. The system uses a look-up table to store and access optical density vs. exposure characteristics for several types of radiographic film.
Abstract: A beam scanning system having a beam reflecting element, such as a mirror, disposed in the path of an incident beam defining an optical axis, which is pivotable about two perpendicular axes so as to provide for scanning a reflected beam in two dimensions. A pivot axis is perpendicular to the optical axis and may be provided by a spindle supporting a galvanometer mirror. The second axis coincides with the optical axis and may be provided by a meter driven shaft attached to the mirror support which is rotatable about the optical axis. The reflecting element reflects the beam toward an image plane that is parallel to the incident beam so as to scan a sequence of parallel lines without pincushion errors. An optical f-.theta. correcting lens may be provided in the reflected beam path to correct for tangential spacing errors in the image plane.