Abstract: In a method and device for positioning the level of a slice during the generation of a slice exposure of an examination subject with an x-ray examination device, a reference image of the exterior of the examination subject is recorded by a camera on a line of sight proceeding transverse to the direction of examination. The slice level of a subsequent slice exposure is determined using a slice level marking within the reference image.

Abstract: Method and apparatus for examination of a breast, in which a contrast medium is injected in the breast to be examined, an X-ray beam is emitted in the direction of the breast; a plurality of digital images of the X-ray beam is taken after it has crossed the breast, and a representative image of the contrast produced in the tissues of the breast is calculated from the digital images.

Abstract: In a method and apparatus for producing an overall image from a number of partial images which are produced successively for common playback, a first partial image is produced and stored, and at least a portion of the first partial image, that adjoins a second partial image to be produced, is played back. A survey image is produced for the second partial image and this survey image is simultaneously played back with the first partial image, with overlapping regions adjoining each other. From this simultaneous playback, the correct orientation of the exposure region for the second partial image is selected, and the image acquisition device is correspondingly positioned and the second partial image is produced, The first and second partial images are then joined to form the overall image.

Abstract: A method for providing a virtual contrast agent for blood vessels in a body portion for angioscopy comprising deriving data from a 3D model using, for example, magnetic resonance imaging, computerized tomography (CT), and 3D angio. The data is segmented to provide a segmented 3D model of the blood vessels. A first procedure image is made with a contrast agent present. The 3D model is then registered with the first procedural image and “virtual camera parameters” are obtained. The 3D model is rendered and overlaid onto a second procedure image without contrast, whereby a virtual contrast is achieved.

Abstract: An X-ray diagnostic installation has an X-ray tube, a voltage generator, a planar solid state X-ray image converter for generating raw images, an image system and a playback device. The image system has a device for offset correction that acquires an offset image and stores it in a correction offset memory. The correction offset memory is preceded by a microphony detector that analyzes the current offset image for disturbances due to microphony and allows storage only of a current offset image, that is free of such disturbances.

Abstract: A computer assisted orthopedic surgery planner software for generation of 3D (three dimensional) solid bone models from two or more 2D (two dimensional) X-ray images of a patient's bone. The computer assisted orthopedic surgery planner software reconstructs the bone contours by starting with a 3D template bone and deforming the 3D template bone to substantially match the geometry of the patient's bone. A surgical planner and simulator module of the computer assisted orthopedic surgery planner software generates a simulated surgery plan showing the animation of the bone distraction process, the type and the size of the fixator frame to be mounted on the patient's bone, the frame mounting plan, the osteotomy/coricotomy site location and the day-by-day length adjustment schedule for each fixator strut. All bone models and surgery plans are shown as 3D graphics on a computer screen to provide realistic, pre-surgery guidance to the surgeon.

Abstract: An apparatus including but not limited to a charge-coupled device (CCD)-array sensor positioning mechanism, the positioning mechanism structured to position a CCD-array sensor to capture a first target area; and the CCD-array sensor positioning mechanism further structured to position the CCD-array sensor to capture a second target area proximate to the first target area, the first and second target areas spatially related such that a first radiographic image recorded at the first target area may be combined with a second radiographic image recorded at the second target area to form a composite radiographic image substantially analogous to a single radiographic image of an aggregate target area covered by the first and second target areas.

Abstract: A method and apparatus for displaying an image generated by at least one detector of an imaging unit are disclosed herein. The method includes creating a pixel map identifying locations of bad pixels in an array of pixels in the image detected by the at least one detector, linking the pixel map to the image, and providing for selective display of the pixel map. Bad pixels behave from a group including pixels which do not respond electrically and pixels which are statistically different from surrounding pixels in the array of pixels. The apparatus includes an imaging unit for generating x-rays which pass through a body of interest, at least one detector unit for detecting the x-rays, and a processing unit for identifying bad pixels within the detected image.

Abstract: An x-ray imaging system (10) for generating multiple energy x-ray images is provided. The system (10) includes an exposure switch (32) having an “ON”state. A console (14) is electrically coupled to the exposure switch (32) and contains two or more selected imaging program sets. An x-ray generator (18) generates x-rays. An image detector (28) detects the x-rays and generates two or more electronic signals. An image generation controller (20) is electrically coupled to the image detector (28) and controls the sequencing of the two or more electronic signals. An x-ray controller (12) is electrically coupled to the console (14) and the x-ray generator (18). The x-ray controller signals the image generation controller (20) to generate the two or more electronic signals sequentially when the exposure switch (30) is in the ON state and in response to the two or more selected imaging program sets. A method for performing the same is also provided.

Abstract: A method of compensation for the thickness of an organ in an X-ray machine of the type comprising an X-ray source and a detector of the beam of X-rays after it has passed through the organ, the detector being capable of converting the X-ray beam into a digital electronic signal, in which, from a digitized image, an image of the radiologic thicknesses of an organ traversed by the X-ray beam is calculated, a thickness threshold is defined, from this there is derived an algebraic compensation image to bring the pixels of a level below or above the threshold back to the value of the threshold, and the thickness image and a proportion of the compensation image are summed up, to obtain a compensated thickness image.

Abstract: An apparatus including but not limited to a charge-coupled device(CCD)-array sensor positioning mechanism, the positioning mechanism structured to position a CCD-array sensor to capture a first target area; and the CCD-array sensor positioning mechanism further structured to position the CCD-array sensor to capture a second target area proximate to the first target area, the first and second target areas spatially related such that a first radiographic image recorded at the first target area may be combined with a second radiographic image recorded at the second target area to form a composite radiographic image substantially analogous to a single radiographic image of an aggregate target area covered by the first and second target areas.

Abstract: The invention relates to a method of reconstructing images from cone beam projection data from an examination zone (3) of an object to be examined. The cone beam projection data is acquired by means of an X-ray device which includes an X-ray source (1) and an X-ray image intensifier (2), the X-ray source (1) being guided along a trajectory around the examination zone (3) in order to acquire the projection data. First projection data are then acquired from the examination zone (3) in a first mode of operation of the X-ray image intensifier (2) which involves a low resolution. For a sub-zone (4) of the examination zone (3) second projection data is acquired in a second mode of operation of the X-ray image intensifier (2) which involves a high resolution. Subsequently, the first and second projection data is combined so as to form third projection data.

Abstract: Certain embodiments of the present invention provide a method and system for cine EBA/CTA imaging. The method includes positioning a patient at a first position in a CT scanner, scanning the patient during a first sweep beginning at a first triggering event, moving the patient to a second position, scanning the patient in a second sweep beginning at a second triggering event, and forming a series of motion images based on at least the first and second sweeps.

Abstract: The present technique provides a variety of processing schemes for decomposing soft tissue and bone images more accurately from low and high-energy images acquired from an imaging system, such as a dual-energy digital radiography system using flat-panel technology. In particular, a pre-decomposition process is provided for spatially matching, or registering, low and high-energy images using warping registration prior to dual energy image decomposition, which creates the soft tissue and bone images. Accordingly, the pre-decomposition process reduces motion artifacts between the low and high-energy images, thereby improving image clarity of the decomposed soft tissue and bone images.

Abstract: An x-ray imaging system includes an x-ray source for projecting imaging radiation onto a sampled object that is secured by a support member and a detector support assembly having multiple detecting modules distributed in a sparse configuration for detecting imaging radiation that has passed through the object. The x-ray source and the detector support assembly are on opposite sides of the support member. Relative displacement is provided between the object and the imaging radiation. By providing the relative displacements and illuminating the object with pulses of imaging radiation at selected intervals, a time series of successive sub-images corresponding to overlapping regions of the object is captured by each module. Computational algorithms combine the captured sub-images to form a composite three-dimensional description of the sampled object. There are multiple pulses of x-ray illumination for each region of the object, and each pulse irradiates more than one detecting module.

Abstract: A mover 13 moves and disposes a radiation detector 12 in a photographing position P1, and projected image data D21 is acquired for each of the directions of projection at this time. By use of the mover 13, the radiation detector 12 is moved to a photographing position P2, P3, and projected image data D22, D23 is acquired in each of the photographing positions as is the case with the photographing position P1. A projected image data synthesizer 31 in the image processor section 30 synthesizes the projected image data D21, D22, and D23 to generate synthesized projected image data D20, which is the projected image data for the entire detection region.

Abstract: Method and apparatus for the management of the dynamics of a digitized radiological image of the type comprising a radiation source and a means of detection of the radiation source after it has crossed an object of interest, the means of detection capable of converting the radiation source into a digital electronic signal, including means for defining an intensity threshold from a so-called digitized input image, means for deducing therefrom an algebraic compensation image to raise the pixels of level below the threshold, and means for adding the input image and the compensation image, in order to obtain a compensated image which preserves the differences and the real relations between internal structures of the object of interest. The method and apparatus is useful in X-ray radiological imaging of internal organs of the human body.

Abstract: In a method for the presentation of image information of an examination subject, those tomograms in a series or set of tomograms that differ in terms of the position relative to a dimension are colored, and are subsequently superimposed to form a resultant image. A color having a position on a color scale corresponding to the position of the respective tomogram with respect to the dimension is used to color that tomogram.

Abstract: A method of obtaining in image of the phase change introduced by an object in penetrating radiation incident on the object includes irradiating the object with penetrating radiation having high lateral spatial coherence, and receiving at least a portion of the radiation at a detector after the radiation has merged from the object and thereby obtaining and storing at least two intensity records for the received radiation each including intensity values at predetermined intervals. These values are utilized to derive a grid of values defining an image of the phase change introduced by the object in the penetrating radiation. The intensity records are obtained at a uniform finite distance after the radiation has emerged from the object, and are for respective different energy distributions of the detected radiation. Apparatus is also disclosed.

Abstract: The origin of a cone or fan beam of B, &ggr;, or x radiation is moved in a continuous path such as a circle or is stepped among a two-dimensional grid of preselected points. The cone beam of radiation passes through a patient (14) in an imaging region (12) and is detected by a detector array (16). A data collection circuit (20) samples the detector array to generate radiation intensity sub-images. A circuit (56) monitors the shifting of the focal spot and controls an image shifting circuit (58) to shift physical coordinates of the sampled sub-image analogously. A sub-imaging combining circuit (60) interleaves or otherwise combines spatially shifted sub-images. In one embodiment, the combined sub-images forms a higher resolution composite image representation. In another embodiment, a plurality of combined, spatially shifted sub-images are collected at angularly offset orientations around the subject and are reconstructed into a higher resolution composite image representation.

Abstract: A system and method for high resolution digital x-ray imaging which utilizes multiple imaging sensors is disclosed. In the preferred embodiment, the system includes multiple imaging sensors with overlapping fields of view. The imaging sensors are preferably interfaced with a general purpose computer capable of seamlessly combining the multiple images captured by the multiple imaging sensors.

Abstract: A method and device for sampling a fragment of tissue in which a contrast medium is injected into an organ to be examined and highlights parts containing that contrast medium in an image obtained by emitting a beam of X-rays. At least one pair of radiographic images is captured from a first position and a second position of an X-ray emitter during a phase of increasing attenuation due to the contrast medium. A specific area is identified from the pair of images in which a tissue fragment is to be sampled. The images of the pair of images are combined to determine the three-dimensional coordinates of the specific area.

Abstract: A method for acquiring an elongated radiographic image comprising: positioning an elongated object between a source of x-rays and a digital image capture device having a known imaging dimension which is less than a like dimension of said elongated object; moving said device in a direction parallel to said known imaging dimension to sequential contiguous positions to acquire a sequence of radiographic images of said elongated object; and rotating said source of x-rays about an axis perpendicular to said direction of moving said device in coordination with said moving project said x-rays from said source toward said device.

Abstract: Superimposed X-ray and video images can be obtained by acquiring the respective images from the optically equivalent points in space. One or more mirrors may be used to acquire the images and direct them towards the camera. The images can then be combined by warping one onto the other.

Abstract: The invention relates to a method of reconstructing images from cone beam projection data from an examination zone (3) of an object to be examined. The cone beam projection data is acquired by means of an X-ray device which includes an X-ray source (1) and an X-ray image intensifier (2), the X-ray source (1) being guided along a trajectory around the examination zone (3) in order to acquire the projection data. First projection data are then acquired from the examination zone (3) in a first mode of operation of the X-ray image intensifier (2) which involves a low resolution. For a sub-zone (4) of the examination zone (3) second projection data is acquired in a second mode of operation of the X-ray image intensifier (2) which involves a high resolution. Subsequently, the first and second projection data is combined so as to form third projection data.

Abstract: An image processing method includes the acquisition of a succession of low-resolution images. A succession of mask images is derived from the low-resolution images. Furthermore, a high-resolution image is acquired. The mask images are applied to the high-resolution image as bandpass filters in order to form a filtered high-resolution image. The filtered high-resolution image represents image information relating to a particular phase of a dynamic process, such as the passage of blood through the vascular system of a patient. The image processing method is used, for example in MR angiography or in X-ray angiography. An MRI system or an X-ray examination apparatus is provided with an image processor for carrying out the image processing method according to the invention.

Abstract: Each of image signals representing radiation images of a single object is weighted with a weight factor. Signal components of the weighted image signals representing corresponding pixels in the radiation images are subtracted from each other, and a difference signal representing an image of a specific structure of the object is obtained. The weight factor is set for each pixel in each radiation image and in accordance with a difference between logarithmic values of radiation doses with respect to corresponding pixels in the radiation images, or in accordance with a logarithmic value of a ratio between the radiation doses with respect to the corresponding pixels in the radiation images.

Abstract: Method and apparatus for medical radiology and, in particular, galactography in the field of mammography. The method of obtaining radiological images in galactography comprises acquiring of a first radiological image of the breast in a compressed state: introducing a contrast medium in a part of the breast; acquiring at least a second radiological image of the breast in the compressed state and with contrast medium; and partial or complete subtraction of the first image in relation to the second image, or vice versa. An apparatus for use of the method comprises means for maintaining a breast compressed or immobilized and means for holding a catheter or the like for introducing a contrast medium in the breast.

Abstract: An x-ray imaging system images an object by transmitting primary signals and includes a collimator placed between detectors of the x-ray imaging system. The collimator reduces respective scatter components of total signals including a primary signal component and a scatter signal component. One of the detectors detects the total signals, the collimator collimates the primary signals of the total signals focally aligned with the collimator and traveling through the one of the detectors, another of the detectors detects the collimated, primary signals. The x-ray imaging system reduces the scatter components of the total signals detected by the one of the detectors based on the detected, collimated signals and the corresponding, detected, total signals. In another aspect, a detector includes regions of reduced absorption.

Abstract: An examination program is selected based on an input of an examination method or a region to be inspected on the side of an diagnostic X-ray system, and contrast conditions suitable for contrast examination which is realized by the selected examination protocol are transmitted to a contrast medium injector through a network or the like. The contrast medium injector receives the transmitted contrast conditions and performs control regarding contrast medium dosage based on the contrast conditions.

Abstract: A method and apparatus for providing a high-quality representation of a volume having a real-time 3-D reconstruction therein of movement of an object, wherein the real-time movement of the object is determined using a lower-quality representation of only a portion of the volume. Movement of the object is detected in a 2-D X-ray fluoroscopy image and is reconstructed in a 3-D angiography (X-ray) reconstruction. Using a common C-arm and X-ray geometry advantageously, the 2-D and 3-D data representative of vascular structures of a patient is acquired, thereby facilitating the merger of the real-time 2-D fluoroscopic images with the 3-D reconstructed vascular structures in a common 3-D-visualization framework. Also described is a technique for 3-D reconstruction of a catheter from real-time 2-D fluoroscopic images and stored 3-D angiography data, so as to present the 3-D reconstructed catheter in the common coordinate frame.

Abstract: Method of generating three-dimensional images of an object from at least two series of two-dimensional images comprises a third series of two-dimensional image is generated by subtracting the images of one of the two series of images from the other series; a three-dimensional reconstruction is made from the third series of images in order to obtain a subtracted three-dimensional image; a three-dimensional reconstruction is made from the first series of images in order to obtain a three-dimensional image corresponding to the first series; and a three-dimensional image corresponding to the second series of two-dimensional images is generated. A device for generating the three-dimensional images; a radiology apparatus including the device; a computer program code for carrying out the method; and a support having the program stored therein.

Abstract: A system and method for creating MR images using mask data that is copied forward for on-the-fly image subtraction for use within such techniques as MR angiography is disclosed. The invention includes acquiring an MR mask image comprised of a plurality of k-space lines, and then copying the k-space line data of the MR mask image into a number of different memory locations. The number of different memory locations corresponds to a preselected number of MR image acquisitions as set by an MR operator. The invention next includes acquiring the preselected number of MR images, each comprised of k-space line data. As the k-space line data is acquired, it is then immediately accumulated in one of the memory locations having the MR mask image k-space line data. By setting a polarity of the data stored, each acquired k-space line of an acquired MR image is subtracted from a corresponding k-space line of the MR mask image in real time. The image is then reconstructed using the subtracted k-space line data.

Abstract: A method of obtaining in image of the phase change introduced by an object in penetrating radiation incident on the object includes irradiating the object with penetrating radiation having high lateral spatial coherence, and receiving at least a portion of the radiation at a detector after the radiation has merged from the object and thereby obtaining and storing at least two intensity records for the received radiation each including intensity values at predetermined intervals. These values are utilized to derive a grid of values defining an image of the phase change introduced by the object in the penetrating radiation. The intensity records are obtained at a uniform finite distance after the radiation has emerged from the object, and are for respective different energy distributions of the detected radiation. Apparatus is also disclosed.

Abstract: An apparatus including but not limited to a charge-coupled device(CCD)-array sensor positioning mechanism, the positioning mechanism structured to position a CCD-array sensor to capture a first target area; and the CCD-array sensor positioning mechanism further structured to position the CCD-array sensor to capture a second target area proximate to the first target area, the first and second target areas spatially related such that a first radiographic image recorded at the first target area may be combined with a second radiographic image recorded at the second target area to form a composite radiographic image substantially analogous to a single radiographic image of an aggregate target area covered by the first and second target areas.

Abstract: In a method and apparatus for reducing line artifacts in a CT image D1, which is acquired during a scan by a CT device with a detector system having a number of proper detector channels and at least one defective detector channel, the image M1 is obtained first by a median filtering. the image D1, which contains a circle artifact on a circle K1. A difference value image F1=D1−M1 is then produced. Filtering then is carried out in each picture element of the image F1 in the direction of the tangents t11 and t21 to the circle K1 extending through the respective picture element in order to produce two resulting images G11 and G21. A correction image D2 is subsequently produced by subtracting the resulting images G11 and G21 from D1.

Abstract: Method and apparatus for examination of a breast, in which a contrast medium is injected in the breast to be examined, an X-ray beam is emitted in the direction of the breast; a plurality of digital images of the X-ray beam is taken after it has crossed the breast, and a representative image of the contrast produced in the tissues of the breast is calculated from the digital images.

Abstract: A method of and a device for forming an image of an irradiated object in which images are formed with different exposure levels and the differently exposed images are combined so as to form a single image. The device includes a source and an imaging device which is connected to the source in order to form the image, the imaging device being arranged to form images with different exposure levels and being provided with an image processor in which the differently exposed images are combined so as to form the single image. The device produces images of a quality which is comparable to that of images acquired by means of a device having a much larger dynamic range.

Abstract: Method and apparatus for the management of the dynamics of a digitized radiological image of the type comprising a radiation source and a means of detection of the radiation source after it has crossed an object of interest, the means of detection capable of converting the radiation source into a digital electronic signal, including means for defining an intensity threshold from a so-called digitized input image, means for deducing therefrom an algebraic compensation image to raise the pixels of level below the threshold, and means for adding the input image and the compensation image, in order to obtain a compensated image which preserves the differences and the real relations between internal structures of the object of interest. The method and apparatus is useful in X-ray radiological imaging of internal organs of the human body.

Abstract: The invention relates to the inspection of an object (105) by radiography, this object possessing a crystal lattice. It consists of submitting the object (105) to electromagnetic radiation (103) to obtain a radiographic image of the object on receptor means (114) the radiographic image obtained, corresponding to one exposure, being a composed image resulting from a relative displacement of the object (105) which makes it possible to substantially reproduce the object while significantly attenuating the parasitic elements produced by diffraction of the electromagnetic radiation on the crystal lattice of the object.

Abstract: A process for producing a diagnostic quality x-ray image from a fluoroscopic sequence. Initially a sequence of numerous individual fluoroscopic images are acquired. These images are stabilized to produce stabilized individual images wherein the subject is located in a consistent position within said stabilized individual images. The stabilized individual images are fractionated and summated to create a resultant image. The resultant image unexpectedly has superior quality when compared to any of the individual fluoroscopic images.

Abstract: An assembly for recording a radiation image of an elongate body comprises a plurality of cassettes each conveying a recording member and each having a length that is smaller than the length of the elongate body. Supporting devices are arranged for holding the plurality of cassettes in a staggered arrangement so that the length of the staggered arrangement is at least equal to the length of the elongate body. This assembly is exposed to the radiation image of an elongate body. By use of partial images which are read from each of the recording members, the entire image of the elongate body is reconstructed.

Abstract: Radiation having a high energy level, in which high energy components have been emphasized relatively to other energy components, is irradiated to an object, and high energy image information corresponding to the radiation having a high energy level, which radiation carries image information of the object, is thereby stored on a radiation detector. The radiation detector is provided with a flat surface-like scintillator, which converts radiation into visible light, and a solid-state photodetector, which is overlaid upon the scintillator and is constituted of a plurality of solid-state photo detecting devices located in a matrix-like pattern. The stored high energy image information is read from the radiation detector.

Abstract: The invention relates to a radiography process for use with an object moving between a source and a detector involving a determination of a plane called the object projection plane and the production of radiographic images of the object while it is moving using the source, the detector and the combination of the various contributions of projections of the projection plane in the series of radiographic images.

Abstract: A method of obtaining in image of the phase change introduced by an object in penetrating radiation incident on the object includes irradiating the object with penetrating radiation having high lateral spatial coherence, and receiving at least a portion of the radiation at a detector after the radiation has merged from the object and thereby obtaining and storing at least two intensity records for the received radiation each including intensity values at predetermined intervals. These values are utilized to derive a grid of values defining an image of the phase change introduced by the object in the penetrating radiation. The intensity records are obtained at a uniform finite distance after the radiation has emerged from the object, and are for respective different energy distributions of the detected radiation. Apparatus is also disclosed.

Abstract: An X-ray examination apparatus comprises an X-ray detector (1) for deriving an optical image from an X-ray image. An image pick-up device (2) derives an image signal from the optical image. The image pick-up device (2) is provided with an image sensor (3,4) having a plurality of sensor elements. The effective surface area of the sensor elements differs for different optical spectral components of the optical image. The image pick-up device is provided with an adjusting system for selecting an optical spectral component. The image signal is derived from the selected optical spectral component.

Abstract: An image sensing apparatus using a solid state image sensor has the capability of correcting an image signal including an intensity variation due to the variation in the intensity of a radiation from a radiation source and also including an intensity variation due to the variation in conversion efficiency of photoelectric conversion elements in such a manner that only the variation in conversion efficiency is corrected thereby suppressing an artifact which would occur in conventional apparatus. A shading distribution (distribution data) is measured by sensing an X-ray through no object to be examined or through an object whose transmittance to the X-ray is well known. The component of the X-ray intensity distribution is separated from the obtained shading distribution data thereby obtaining a pixel-to-pixel variation in conversion efficiency of the solid state image sensor. The image signal is corrected based on the pixel-to-pixel variation in conversion efficiency obtained.

Abstract: A digitized secondary image which promotes predetermined elements of interest of the object is created from each primary image, digital processing for two-dimensional mutual resetting of the secondary images is carried out per pair of consecutive images, for each current reset secondary image a region common to the said current image and to the following reset secondary image is defined which is bounded by the two respective median horizontal lines of the two reset secondary images, and the digitized overall radiographic picture is created from the upper region of the first reset secondary image of the succession, lying above the common region of this first image, from the lower region of the last reset secondary image of the succession, lying below the common region of this last image, and from the common regions of each pair of reset secondary images.

Abstract: A method for forming an assembled image from successive sub-images comprises the step of acquiring the sub-images, notably X-ray images, with an X-ray detector comprising an essentially flat X-ray-sensitive surface. An X-ray examination apparatus comprises an X-ray detector having a flat X-ray sensitive surface. Advantageously, difference images are derived from successive sub-images. For example, the assembled image derived from the difference images is used to display blood flow patterns in a patient's vascular system.

Abstract: A system for scanning an x-ray target in an x-ray imaging system with a charged particle beam. The system for scanning comprises deflecting the charged particle beam to re-illuminate the portion of the object to be imaged in a time period that is sufficiently small to prevent image blurring during image reconstruction. The system for scanning further comprises a scan processing system for processing x-ray transmissiveness information received as a result of a scanning pattern that re-illuminates an object.