Abstract: The invention concerns a device comprising fluid elements arranged in a matrix configuration, the level of fluid in each element being controllable by means of an electric force.

Abstract: The invention concerns an X-ray examination device, including an X-ray source and an X-ray detector, for forming an X-ray image of an object, an X-ray filter, arranged between the X-ray source and the X-ray detector, and adjusting means, connected to the X-ray filter for adjusting it. The adjusting means comprise a graphics device, cursor control means for defining a region of interest in an image of said object, displayed on said graphics device, and processing means, connected to the X-ray filter, for calculating the region of interest and adjusting the filter accordingly. The X-ray filter includes filter elements having an X-ray absorptivity which can be adjusted by controlling a quantity of X-ray absorbing liquid within the individual filter elements. The filter elements are capillary tubes, and means for applying electric voltages to the individual capillary tubes are provided for controlling the quantity of X-ray absorbing liquid therein.

Abstract: In an X-ray computed tomography apparatus having a radiation filter, a patient attenuation value representative of the linear beam attenuation by a patient under examination is determined in an equation containing a correction function The correction function is determined by first determining a set of reference overall attenuation values that, for a given different thicknesses of a reference material and different thicknesses of the radiation filter arrangement, represent the actual overall attenuation by the two materials. Then, an appertaining attenuation error value is determined for each reference overall attenuation value. Subsequently, a variable is defined changes in a direction transverse to straight lines of constant attenuation error values in a characteristic field of the attenuation error.

Abstract: The invention relates to an X-ray examination apparatus which includes an X-ray source, an X-ray detector, absorption means arranged between the X-ray source and the X-ray detector, a control unit for adjusting the absorption degree of the absorption means, an image processing unit and a display unit. In order to perform an automatic adjustment of the absorption means, the absorption degree therein is optimized in dependence on user-specific parameters (r) and/or apparatus-specific parameters (s) and/or structure parameters (C) and/or parameters (r) classifying the subject matter of the image.

Abstract: A shield is placed on a patient's body over a secondary organ adjacent a target organ. The shield is partially transparent to x-ray radiation. A CT scan of the target organ is conducted according to conventional protocols and technical parameters. No artifacts are formed in the diagnostic portion of the CT image and there is no degradation of the diagnostic portion of the CT image. A reduction of between about 40% and about 60% in the radiation dose of the secondary organ as compared to the same CT scan made without the shield is achieved.

Abstract: The present invention, in one form, is an imaging system which, in one embodiment, utilizes a filter assembly including a plurality of filter portions for altering the intensity and quality of an x-ray beam. Specifically, in one embodiment, by positioning the filter assembly so that the x-ray beam is filtered by the first portion of the filter assembly, the x-ray beam is altered to perform a body portion scan. By positioning the filter assembly to the second portion, the x-ray beam is altered to perform a head portion scan.

Abstract: An X-ray device with an X-ray source to produce a beam of X-ray radiation, an X-ray detector to detect this radiation and an X-ray filter with filter elements which is positioned between the X-ray source and the X-ray detector to attenuate the X-ray beam in each independent filter element individually. Every filter element (213) can contain a fluid (32) which is electrically conducting and X-ray absorbing, which is supplied via a transport channel (30), whereas the value of the X-ray absorption of each filter element can de discretely adjusted by a stepwise adjustment of the level of the fluid (32) within each filter element.

Abstract: The invention relates to a method of manufacturing a filter which includes a number of ducts formed by a number of deformable foils. The foils have electrically insulating outer sides, with electrically conductive bands which are separated from one another by electrically insulating bands. The electrically conductive bands on a first outer side of the foil are arranged so as to be offset relative to the electrically conductive bands on the second outer side of the foil. The foils are stacked. The oppositely situated electrically insulating bands of the oppositely situated foils are interconnected. The foils are ultimately moved away from one another in a direction transversely of the foils in order to form the ducts between the interconnected foils. At least one detached, electrically insulating section is situated in a prolongation of at least one electrically conductive band and is not connected to an oppositely situated foil.

Abstract: The present invention, in one form, is a system which, in one embodiment, utilizes a pre-patient filter to attenuate detector array signals to indirectly determine a voltage applied to an x-ray source. Specifically, in one embodiment, the pre-patient filter includes a plurality of attenuating portions. By radiating an x-ray beam from the x-ray source through the different attenuating portions of the filter, the signals intensities at a detector array are attenuated differently. Utilizing an attenuation reference for the filter and a ratio of the measured attenuated signal intensities, the voltage applied to the x-ray source may indirectly be determined.

Abstract: A variable attenuation apparatus for use with a radiation-blocking liquid and a radiation source having an attenuation chamber capable of containing a layer of the radiation-blocking liquid and an adjustment device for selectively metering the thickness of the layer of the radiation-blocking liquid, whereby changes in the thickness of the layer alter the radiation transmitted through the attenuation chamber. In one embodiment, an adjustment device includes a reservoir for holding the radiation-blocking liquid and a siphon connection device for allowing the transfer of the radiation-blocking liquid between the reservoir and the attenuation chamber, wherein the thickness of the layer in the attenuation chamber varies in response to changes in elevation of said reservoir, so that an increase in the thickness of the layer causes a drop in the radiation transmitted through the attenuation chamber.

Abstract: The invention relates to an X-ray examination apparatus which includes an X-ray filter for locally attenuating the X-ray beam. The X-ray filter includes a plurality of filter elements. The X-ray absorption of a filter element is adjusted by way of the quantity of X-ray absorbing liquid present in the filter element. The filling of the filter element is adjusted by means of an electric voltage. In addition to the X-ray absorbing liquid, the filter element contains a second liquid which is present at an interface between the X-ray absorbing liquid and the filter element, said second liquid being chemically inert relative to the X-ray absorbing liquid and having an electrical conductivity which deviates from that of the first liquid.

Abstract: An X-ray examination apparatus of this invention comprises an X-ray source, an X-ray detector and an X-ray filter which is located between the X-ray source and the X-ray detector. The X-ray filter includes filter elements, notably capillary tubes, and the X-ray absorption of separate filter elements can be controlled by controlling a quantity of X-ray absorbing liquid in the respective filter elements. The quantity of X-ray absorbing liquid in the individual filter elements is controlled by way of electric voltages applied to the individual filter elements. The filter elements are formed as spaces between deformed foils which are arranged in a stack which is expanded in the direction transversely of the foils. Adjacent foils are locally attached to one another along seams. The stack is arranged between rigid plates and buffer elements are provided between the rigid plates and the stack. The buffer elements are contractable in the direction transversely to the direction of expansion of the stack.

Abstract: A filter having compensating plates, each having a first plate element which can be moved translationally with respect to a frame and a second plate element which can be moved relative to the first plate element so that, when the plates are in an active position, the thickness of absorbent material through which the X-ray beam passes is constant.

Abstract: A method for attenuating x-rays which is insensitive to the x-ray energy employs forward scattering through a filter element to minimize energy shifts due to Compton scattering. Efficiency can be enhanced by employing a material with a large small angle scattering cross section. Since attenuation in the filter increases rapidly with decreasing x-ray energy, the filter provides larger, thinner scattering areas for low energy x-rays and smaller, thicker scattering areas for higher energy x-rays. By adjusting the relative fractions of the scattering areas and their thicknesses, the total scattering yield through the filter can be made to be essentially independent of x-ray energy over a broad band of x-ray energies.

Abstract: An object (22) is positioned on a patient support (25) between an x-ray source (10) and an x-ray detector assembly (15). The x-ray source (10) is selectively activated to transmit an x-ray beam (20) through an imaging region (32) to the x-ray detector assembly (15). Positioning of the object (22) on the patient support (25) is such that a gap 33 exists in the imaging region (32) through which x-rays may pass unattenuated. An x-ray equalization filter (30) is introduced into the gap 33 and substantially conforms to its shape. The equalization filter (30) comprises a fluid medium disposed in a flexible receptacle. The fluid medium contains x-ray attenuating material suspended in a gel base. Placement of the equalization filter (30) in the gap reduces the number of unattenuated x-rays reaching the x-ray detector assembly (15) thereby enhancing image quality.

Abstract: The device is used for compensating a hyper transparency area due to air inside or outside an organ while using a gantry mounting radiography apparatus with digital subtraction (DSA). The device comprises compensating filters and a supporting assembly for connecting the filters in front of the X-ray source. Each filter extends in a filter plane while the organ defines a median plane in which the rotation axis of the arms of the apparatus is substantially lying. The supporting assembly is designed to keep the filter in front of the X-ray source and in registry with the X-ray source and the hyper transparency area while keeping the filter plane parallel to the reference plane during rotation of the arms. Unlike existing X-ray compensating devices which are stationary, the present invention automatically sets itself for radiography of different views in function of the rotation of the arms of the apparatus.

Abstract: A charged particle beam irradiation system includes a beam spreading device, a ridge filter, a range shifter, a collimator, and a bolus. Further, on a supporting plate in the ridge filter, a plurality of ridge components are arranged, and shielding elements are attached at the top parts of a part of the plurality of the ridge components.

Abstract: An X-ray examination apparatus includes an X-ray source (1) for emitting X-rays. An object to be radiologically examined is arranged in an examination space. An X-ray detector (2) derives an image signal, for example an electronic video signal, from an X-ray image of the object. An X-ray filter locally attenuates the X-rays partly. The X-ray filter is arranged between the X-ray source and the X-ray detector and the X-ray filter is provided with filter elements whose X-ray absorptivity can be adjusted on the basis of an amount of X-ray absorbing liquid present within the individual filter elements.The X-ray examination apparatus includes an X-ray collimator for locally intercepting the X-rays. The X-ray collimator is arranged between the X-ray source and the examination space and is provided with collimator elements which can be switched between an X-ray transmitting state and an X-ray intercepting state.

Abstract: An x-ray filter is used to permit higher intensity x-ray exposure to the upper thoracic spine while maintaining a normal level of x-ray exposure to the cervical spine. The resulting x-ray image allows a viewer to count the seven cervical vertebrae in order to identify the position of the first and second thoracic vertebrae. The filter is formed by a pair or mating blocks of x-ray absorbing material. The filter has a first region for absorbing x-ray radiation to decrease exposure of the cervical spine and has a second region with a V-shaped opening which allows higher x-ray transmission to the thoracic spine while reducing exposure on areas adjacent to the thoracic spine. The filter is formed by two shaped filter blocks which fit together to create the first and second regions. The edges of the filter blocks which form the V-shaped opening are beveled to create a generally trapezoidal exposure region which is aligned with the upper thoracic spine.

Abstract: An X-ray examination apparatus (1) is provided with an X-ray source (2) and an X-ray detector (5) wherebetween there is arranged an X-ray filter (6) which includes filter elements (7) whose X-ray absorptivity can be adjusted by controlling the quantity of X-ray absorbing liquid (31) in individual filter elements (7). The filter elements (7) are formed by spaces between electrically conductive tracks (9) provided on parallel plates (8). The parallel plates are arranged in a reservoir (31) for the X-ray absorbing liquid. The liquid level in the vicinity of an electrically conductive track is controlled on the basis of an electric voltage applied to the relevant electrically conductive track (9).

Abstract: The present invention provides for an improved automatic x-ray beam equalizer. By analyzing an initial low dosage x-ray image of an object, an attenuation pattern can be calculated. An equalization pattern, generated from the attenuation pattern, can then be created in a mask and placed in the path of a full x-ray beam scan using a stepper motor assembly in order to properly attenuate the x-ray signal and create a clearer x-ray image of the object.

Abstract: Filter (3) for absorbing X-rays (2), having a controllable field-generating matrix arranged on a housing (7). The matrix generates electric or magnetic fields acting on liquids (13, 14) located in the housing. The housing (7) has at least one first and one second chamber (9, 10) which are separated in a sealed fashion from one another by means of a flexible diaphragm (8). The first and second liquids (13, 14) are located in the first and second chambers (9, 10) respectively, and differ in their X-ray absorption characteristics. At least one of the liquids is a magneto-rheological or an electro-rheological liquid, depending on the type of matrix provided. In operation, a minimum pressure is applied to at least one of the liquids, and the localized fields produced by the matrix cause the liquids (13, 14) to alter their respective thickness ratios, to provide a an X-ray filter having location-specific absorption characteristics.

Abstract: The present invention provides for an improved automatic x-ray beam equalizer. By analyzing an initial low dosage x-ray image of an object, an attenuation pattern can be calculated. An equalization pattern, generated from the attenuation pattern, can then be created in a mask and placed in the path of a full x-ray beam scan in order to properly attenuate the x-ray signal and create a clearer x-ray image of the object.

Abstract: An X-ray examination apparatus includes an X-ray filter with a plurality of filter elements for locally attenuating the X-ray beam. The X-ray absorptivity of each filter element is controlled by the amount of X-ray absorbing liquid with which the filter element is filled. The filling of filter elements is controlled by a voltage. The X-ray absorbing liquid contains a suspension of very small X-ray absorbing particles.

Abstract: A system of radiography includes the provision of a cassette which is to be subjected to exposure from radiation beam. The cassette includes a screen layer and a filter layer having regions of different optical density and an imaging film. The filter acts to reduce the exposure of the film to the effect of radiation. The cassette is useful for dental images, particularly of the temporamandibular joint.

Abstract: An x-ray filter which produces a uniform distribution of the image contrast and the image brightness, with an optimally reduced skin dose has a pre-filter for the total x-ray beam and an edge filter, which leaves free a central region of the x-ray beam. The pre-filter is made of a material having an atomic number less than 60, such as copper, and the edge filter is made of a material having an atomic number between 64 and 77.

Abstract: A K-filter is the one attached to an apparatus for serial high-speed rotatography for photographing an object to be examined by use of X-rays. The filter comprises two K-containers (5a and 5b) in which a space is defined for fluidly containing a radiopaque fluid substance, and a radiotransparent region (2) formed between the two K-containers (5a and 5b). The K-containers (5a and 5b) are pivotally supported by a supporting member (1a) and are of the inversion type which allows the radiotransparent region sides of the K-containers to move. Therefore, when this apparatus is rotated at a high speed to more than 180.degree., it is possible to conduct filtering under any conditions such as an inclined posture, not the horizontal posture, under which photographing is started.

Abstract: An X-ray examination includes a filter for limiting the dynamic range of an X-ray image formed on an X-ray detector by irradiation of an object, for example a patient to be examined, by means of X-rays. The filter has a number of electrodes and grains or powder particles containing an X-ray absorbing material and suspended in a suspension liquid. When a voltage is applied to electrodes, X-ray absorbing material in the suspension will move to the excited electrodes under the influence of electrophoresis. A distribution with a desired X-ray absorption profile is adjusted by application of a suitable voltage pattern. The electrodes may have dimensions of, for example 0.5.times.0.5 mm, enabling an X-ray absorption profile to be obtained with a high spatial resolution. The X-ray absorption profile can be changed within a brief period of time, for example within one second, by changing the voltage pattern on the electrodes.

Abstract: The invention is related to a soft-tissue filter apparatus for a cephalostat, said apparatus being capable of positioning the patent (P) stationary for exposing radiographic images of the skull. The apparatus comprises an x-ray source (13) whose collimated (14) x-ray beam (XR) can be directed through the skull of the patient (P) onto an x-ray film (RF) contained in a cassette (23). The apparatus further comprises a soft-tissue filter assembly (10) in which to the region of one side (a) of the x-ray beam (XR) is placed an radiation-absorbing filter element (19) movable by means of a drive motor (15) transversely (B) to the x-ray beam (XR). The apparatus incorporates a light indicator unit (20) comprising a light source (25) capable of projecting onto the side of the face of the patient (P) a light marker line (LL) which is transferrable along the adjustment direction (B) of the soft-tissue filtering assembly.

Abstract: A common application of X-ray fluoroscopy is in monitoring the location of a catheter inside a body. Such catheters may be used for balloon angioplasty, laser ablation, or like procedures that are now often used in place of traditional invasive surgery. Reliable and fast determination of the tip location from the fluoro images using the digital image processing technique is required. The present invention relates to a method for tracking a catheter probe or similar object during a fluoroscopic procedure as may be utilized, for example, in conjunction with apparatus and methods that confine full X-ray dosage to a central area, compensating for the reduced X-ray dosage in the peripheral areas by computer imaging enhancement.

Abstract: An X-ray apparatus includes an X-ray pickup window through which synchrotron radiation light is projected, the X-ray pickup window having an X-ray transmission film; and a correcting system for correcting an intensity distribution of the synchrotron radiation light; wherein the X-ray transmission film has at least one of a film thickness distribution and a transmissivity distribution changing substantially in a predetermined direction; and wherein the X-ray transmission film is so disposed that the predetermined direction is substantially aligned with the direction of change of the intensity distribution of the synchrotron radiation light.

Abstract: The present invention is a method for locating an edge portion of an aperture in an X-ray filter member having at least one aperture formed therethrough, such that X-rays passing through the at least one aperture remain unattenuated and strike a subject body in a common region and wherein the X-rays passing through the filter member are attenuated and strike the subject body in a pattern that surrounds, and is adjacent to, the common region.

Abstract: A tissue compensation system and method for making a tissue compensator utilizes a plurality of elongate rods, one end of which contact the treatment surface on the patient, and the other end of which contact and deform a flexible membrane containing a quantity of a material substantially equivalent to tissue of the patient.

Abstract: A method is provided for calibrating a beamline (24) used for X-ray lithography. The beamline includes an elongated evacuated tube (28) extending from an X-ray source (22) for containing the X-ray beam to a closure (32) at an opposite end including a beryllium window. A target wafer (34) aligned with, but external of, the tube is positioned in a plane transverse of the X-ray beamline and is coated with a uniform layer of light sensitive material. A carbon filter (31) intermediate the X-ray source and the target wafer is provided within the tube to block electromagnetic radiation having wavelengths generally in the region of ultraviolet, visible, and infrared ranges of the spectrum. The beam from the X-ray source is scanned through the beamline, through the filter, and onto the target wafer. Thereafter, the wafer is subjected to an etch process thereby forming a contoured surface (34A) emulating the non-uniformities caused by the components of which the beamline is comprised.

Abstract: In an x-ray examination apparatus comprisinga frame (2) to which are connected an x-ray source (3) for emission of an x-ray beam and an x-ray detector (5) that is placed opposite the x-ray source, andfilter means (31) that are placed between the x-ray source (3) and the x-ray detector (5) the filter means (31) comprising an x-ray absorbing filter body (33) and drive means for positioning the filter body in the x-ray beam, the drive means comprise two disk-shaped holding members between which the filter body is placed. The filter body is in a pivot-point pivotably fixed to one holding member and is provided with a pawl that engages a curved radial groove in the second holding member. By joint rotation of the holding members the filter body is translated in the x-ray beam whereas by rotation of one of the holding members only, the curved radial groove causes the filter body to rotate in the x-ray beam.

Abstract: An apparatus for modulating the intensity of an X-ray beam generated by an X-ray tube. The apparatus comprises a set of at least three blades made of a material opaque to X-ray. Each blade comprises a central hub and a pair of symmetrical wings extending away from the hub. All the blades have their hubs slidably mounted on radially projecting shafts symmetrically positioned about a rotor positioned adjacent the X-ray beam and driven at variable speeds. Matching pins and threads are provided on each pair of hub and shaft to cause the corresponding blade to pivot about the shaft on which it is mounted when the speed of the rotor increases and the blades are then moved in unison radially outwardly against the action of a return spring, because of the centrifugal force. The rotor, the blades and the shafts are positioned and sized to cause the blades to intersect the X-ray beam when the rotor is driven.

Abstract: The invention applies to radiological apparatuses for angiographic examination. The invention lies in the fact that an X-ray attenuation filter is disposed between the X-ray source and the patient, said filter introducing attenuation on the path of each X-ray such that the total attenuation to which each X-ray is subjected on its path to the receiver is substantially the same for all of the paths in the X-ray beam, thereby homogenizing the exposure of the image-forming receiver.

Abstract: A lens-like X-ray filter is filled with a liquid, the filter having flexible walls, the filter being between an X-ray source and an X-ray detector in an X-ray examination apparatus. The filter obviates brightness variations in an X-ray image caused by vignetting. The filter thickness is adjustable by the supply and the discharge of a liquid, the filter preserving a quadratic thickness variation from the center to the edges.

Abstract: Method and apparatus for variably compensating a radiographic image irradiates the patient with an x-ray beam. X-ray attenuation (or transmission) variations within the patient are detected and used to modulate the x-ray beam in order to produce an image with equalized exposure and increased SNR. The beam modulation information is used to produce a beam profile image which is an image of the exposure modulation given to the x-ray beam. After the modulated x-ray beam passes through the paient, a compensated image is produced. Both the beam profile image and the compensated image are logarithmically transformed and combined. The logarithmically transformed beam profile image is selectively weighted in order to alter the appearance of the compensated image by various degrees. The combined image is then retransformed and provided to a video monitor for display.

Abstract: In a radiation therapy device isodose curves are adjusted both by a movable plate that is controlled during the irradiation and by a non-movable filter body in the radiation path. The filter body is located in such a manner that it has decreasing absorbability in the opening direction of the plate. On the other hand, the plate produces a decreasing effective dose in its opening direction. by superimposing the two effects, it is possible to have the isodose curve in the object of irradiation rise or fall in the opening direction, so that a wide range of variation in the possible isodose curves is obtained, without having to change the fixed filter body.

Abstract: Method and apparatus for variably compensating a radiographic image irradiates the patient with an x-ray beam. X-ray attenuation (or transmission) variations within the patient are detected and used to modulate the x-ray beam in order to produce an image with equalized exposure and increased SNR. The beam modulation information is used to produce a beam profile image which is an image of the exposure modulation given to the x-ray beam. After the modulated x-ray beam passes through the patient, a compensated image is produced. Both the beam profile image and the compensated image are logarithmically transformed and combined. The logarithmically transformed beam profile image is selectively weighted in order to alter the appearance of the compensated image by various degrees. The combined image is then retransformed and provided to a video monitor for display.

Abstract: An analysis method and system for analyzing coal or other material causes the material to be bombarded with neutrons from a source, and this generates gamma rays from the material which are detected by a detector. The detector has scintillators which generate light when a gamma ray is detected, the light being detected by photomultipliers. Each gamma ray generates two other gamma rays, which may both be wholly absorbed in one or the other scintillator, or one absorbed in one scintillator and one in the other. By analyzing these events, the spectrum of gamma rays may be obtained, giving the composition of the material. One preferred detector has an array of scintillators and coincident gamma ray detection events in three adjacent scintillators detected by detecting if a primary scintillator detector event is coincident with detection events in the other two scintillators.

Abstract: This invention is directed to an improvement in an x-ray lithography system having an x-ray point source of radiation, a wafer disposed in spaced relationship with respect to the source, and a mask disposed between the source and the wafer whereby radiation from the source passes through the mask to the wafer, said improvement comprising the provision of an x-ray absorbent element mounted between the source and the wafer, said element having a radial absorption gradient profile to compensate for radial flux variation of the x-rays.

Abstract: A multioperation accelerator simulating more especially cobalt radiation. According to the invention, an electron accelerator of average energy and a set of targets and filters are provided so as to obtain at least one penetration curve similar to that of cobalt and other closely related curves.

Abstract: Installation allowing the adjustment of compensating filters without exposure to permanent irradiation. According to one possible embodiment, a radiological image is taken (source, brightness or luminance amplifier) and memorized in an image memory prior to being projected by the video projector onto the patient by through-crossing the filter, this filter having brightness absorption and X-ray absorption properties which are similar.

Abstract: The invention relates to a soft tissue filter arrangement in X-ray imaging of a patient's skull by means of a chefalostat, wherein a patient (P) is by means of ear plugs (5) or the like supports preferably fixed relative to imaging coordinates as well as by means of a nasion and/or forehead support (6) set in a determined position and location between an X-ray source (1) and a film (4) or the like imaging medium and wherein the X-ray source is provided with diaphragm (2) for directing X-rays to the patient and restricting them to a proper sized beam (3) for imaging. The arrangement comprises preferably V-shaped filter means (7) whose position relative to the soft tissues of a patient's face in a cross-sectional plane perpendicular to the X-ray beam is adapted to be set on the basis of a distance (D) between said ear plugs (5) or the like supports and said nasion and/or forehead support (6) or on the basis of a patient's skull dimension correlating sufficiently well therewith.

Abstract: A device for positioning a flattening filter in the center of an x-ray radiation, which comprises a drive means for driving the flattening filter between positions outside and inside the x-ray radiation; and a stop means for restricting the inside movement of the drive means to the center position of the flattening filter.

Abstract: A method of testing a ceramic article, comprising photographing a ceramic article by X-ray computed tomography in a state where at least one portion of the ceramic article is placed in a filling material having an X-ray absorption coefficient close to or less than that of the ceramic article in order to simplify the shape of a combination of the ceramic article and the filling material, thereby allowing precise and easy detection of microdefects in a ceramic article which has a complex shape.

Abstract: An attenuation zone plate for coded-aperture imaging of a radiation source has mercury contained within a wedge-shaped chamber in a plastic housing. Reservoir and relief cavities facilitate filling the housing with mercury and accommodate changes in mercury volume. Lead plates positioned on the perimeter of the housing provide a field of view mask. In one embodiment, the housing cover pivots to vary the wedge angle. Advantages include greater facility in precision manufacturing and greater attenuation pattern flexibility.

Abstract: By moving a wedge (18) within the radiographic field during exposure of an area of interest, steps of the wedge are presented one by one at the same film location over sequential exposures. Wedge steps are thus superimposed over an identical position within the radiographic field, and a correlation may then be made between wedge step thickness and film optical density over successive exposures for calibrating the radiographs. A preferred form of the stepped wedge is circular (FIG. 2). An alternate form is a circular ramp (FIG. 3).