Abstract: The present invention relates to an adjusting positioner for a radiation device, comprising: a clamping device detachably connected to the radiation device to clamp said radiation device; a supporter to which said clamping device is connected and a slide path is defined therebetween, wherein the clamping device clamping said radiation device is movable along said slide path in a predetermined direction; and an adjusting device coupled with said clamping device so as to drive said clamping device to move along said slide path. Since the present invention employs above technical solution, it is easy to adjust the position of the radiation device for example, X-ray device, so that the precisely positioning for the radiation device is achieved and a satisfying positioning accuracy is able to obtain.

Abstract: An X-ray CT system according to the invention includes a holding plate which holds X-ray shield plates, a first support plate which supports one short-directional end portion of the holding plate, the first support plate conforming to a bend of the holding plate, a second support plate which supports another short-directional end portion of the holding plate, the second support plate conforming to the bend of the holding plate, and grooves continuously formed on the respective components when the holding plate, the first support plate, and the second support plate are assembled.

Abstract: The invention is related to a method for producing a collimator comprising an X-ray transparent substrate. The innovative method comprises the steps of: forming a slit in the substrate, wherein the slit has first and second side walls; filling the slit with an X-ray absorbing material so that the absorbing material extends from the first side wall to the second side wall; removing part of the X-ray absorbing material thereby forming a second slit that extends from the remaining absorbing material to the second side wall; filling the second slit with X-ray transparent material; removing part of the X-ray transparent material, thereby forming a third slit extending from the remaining transparent material to the second side wall; and finally filling the third slit with X-ray absorbing material. In accordance with the present invention a collimator can be produced having any desired aspect ratio.

Abstract: A medical radiotherapeutic instrument comprising a ray source body, a switch and an end collimation body, a pre-collimation hole and a ray source cavity for placing ray source are defined on the ray source body; the switch is at least one pillar, each pillar is coupled with a drive unit, the pillars are disposed inside the ray source body, a middle collimation hole is defined on each pillar; under the driving of the drive unit, the pillar arise a displacement to move the middle collimation hole into or out of alignment with the pre-collimation hole; the end collimation body is disposed inside the ray source body, and an end collimation hole is defined on the end collimation body, the end collimation hole is connected with the pre-collimation hole through the middle collimation hole to form a therapy path. The present invention is simplified in structure and low in cost, with this structure, it can control the switch separately, and continuously adjust the radiate amount.

Abstract: A radiosurgery system is described that is configured to deliver a therapeutic dose of radiation to a target structure in a patient. In some embodiments, inflammatory ocular disorders are treated, specifically macular degeneration. In some embodiments, other disorders or tissues of a body are treated with the dose of radiation. In some embodiments, the target tissues are placed in a global coordinate system based on ocular imaging. In some embodiments, the target tissues inside the global coordinate system lead to direction of an automated positioning system that is directed based on the target tissues within the coordinate system. In some embodiments, a treatment plan is utilized in which beam energy and direction and duration of time for treatment is determined for a specific disease to be treated and/or structures to be avoided. In some embodiments, a fiducial marker is used to identify the location of the target tissues.

Abstract: An anode for an X-ray source is formed in two parts, a main part and a collimating part. The main part has the target region formed on it. The two parts between them define an electron aperture through which electrons pass to reach the target region, and an X-ray aperture through which the X-rays produced at the target leave the anode. The anode produces at least the first stage of collimation of the X-ray beam produced.

Abstract: The present invention provides an intensity modulated radiation therapy (IMRT) method for treating a target region that minimizes the tongue and groove effect. By minimizing that effect, striping in the final delivered fluence is reduced, which improves the overall quality of the radiation delivery. In the method, compensating functions Ci(x) are added to leaf coordinates ai(x) and bi(x) for all of the leaf pairs i in a leaf sequence algorithm, where Ci(x) is chosen to match the mechanical limitations of the MLC and to minimize non-weighted or weighted sums of the tongue and groove effects, where the weighting is time-dependent, position-dependent, or time- and position-dependent, or to minimize the total treatment time, changes to the original MLC sequence, or the tongue and groove effect distribution variance in spatial or temporal coordinates.

Abstract: Computed tomography (CT) systems and related methods involving multi-target inspection are provided are provided. In this regard, a representative method includes: simultaneously directing X-rays toward multiple targets from an X-ray source; during the directing of the X-rays, independently reorienting the targets with respect to the X-ray source; and obtaining information corresponding to attenuation of the X-rays attributable to the multiple targets for producing computed tomography images of the targets.

Abstract: A method and a device for high spatial resolution imaging of a plurality of sources of x-ray and gamma-ray radiation are provided. The device comprises a plurality of arrays, with each array comprising a plurality of elements comprising a first collimator, a diffracting crystal, a second collimator, and a detector.

Abstract: X-ray collimators, and related systems and methods involving such collimators are provided. In this regard, a representative X-ray collimator includes: a first member having channels located on a surface thereof; and a second member having protrusions located on a surface thereof; the first member and the second member being oriented such that the protrusions extend into the channels to define collimator apertures, each of the collimator apertures being defined by a portion of the first member and a portion of the second member.

Abstract: A scattered radiation collimator element is disclosed for producing a scattered radiation collimator for absorbing scattered radiation which is generated during an examination of an object by interaction of x-ray or gamma radiation used for this purpose. For the purposes of simplification and reducing costs during production, in at least one embodiment, the scattered radiation collimator element includes a plurality of absorber elements, designed in a strip-like or filament-like fashion and arranged adjacent to one another to form an absorber surface.

Abstract: An X-ray CT apparatus and image controlling method thereof that achieves a higher time resolution tomography image on a region of interest (ROI) of an object while reducing a total amount of X-ray irradiation exposure. The X-ray CT apparatus includes an X-ray source for irradiating X-rays over an object, a multi-slice detector provided facing to the X-ray source for acquiring wide range projection data by a first helical scan, a wide range projection data memory unit for storing the wide range projection data, and a narrow range projection data memory unit for storing the narrow range projection data of a designated region of interest (ROI) only. A controlling method for the X-ray CT apparatus acquires narrow range projection data by a second scan on the ROI along a slice direction and generates compounded projection data based on the narrow range projection data and the wide range projection data. The method generates images based on the compounded projection data.

Abstract: An X-ray CT apparatus includes an X-ray detector that is asymmetrically disposed with respect to an irradiation axis of an X-ray and first and second ends that are disposed close to and far from the irradiation axis of the X-ray, respectively. When a scanogram of an object is imaged in one direction only, a part of the object at the first end is missed. Accordingly, scanograms are imaged in first and second directions that are opposite to each other, and then the imaged scanograms are superimposed. The superimposed scanogram is used as an image for setting a scanning range. According to this configuration, although a scanogram is produced by an X-ray CT apparatus having an asymmetrically disposed X-ray detector, it is possible to produce a desired projection data by obtaining scanogram data in the opposite two directions and combining each data. As a result, the accuracy in setting of a scanning position is not deteriorated.

Abstract: Computed tomography (CT) systems and related methods involving post-target collimation are provided are provided. In this regard, a representative method involving post-target collimation of X-rays includes: emitting X-rays toward a target; and collimating the X-rays downstream of the target.

Abstract: Computed tomography (CT) systems and related methods involving forward collimation are provided are provided. In this regard, a representative method involving forward collimation of X-rays includes: emitting X-rays from a housing in which an X-ray source is mounted; collimating the X-rays downstream of the housing; and directing the collimated X-rays at a target.

Abstract: A radiation imaging system is configured by a collimator 30A including a detector 21 with a discrete detection pixel corresponding with a pixel and a plurality of radiation passages 31 and looks into a plurality of detectors 21 through one radiation passage 31 to set a step width of rotation around a rotation center axis X1 only for an angle ?p made by lines provided by connecting a center detector 21 of the radiation passage 31 and the adjacent two detectors 21. In the case of generating a flat plane projection image for one direction, radio-graphing is carried out on a projection image in a plurality of predetermined angle positions (??p, 0, +?p) in the circumferential direction of the rotation center axis X1 and thereby one plane projection image is obtained.

Abstract: A computed tomography system is disclosed herein. The computed tomography system includes a rotatable gantry portion and an x-ray source mounted to the rotatable gantry portion. The computed tomography system also includes a detector assembly mounted to the rotatable gantry portion and positioned to receive an x-ray beam from the x-ray source. The detector assembly includes a plurality of x-ray attenuating collimation plates with a generally x-ray translucent stiffening member attached to one or more of the plurality of x-ray attenuating collimation plates.

Abstract: An X-ray device for irradiating a beam of X-rays on an object to capture an X-ray image of the object is smaller in size and weight than conventional ones. The X-ray device includes an X-ray tube for generating the beam of X-rays and irradiating the beam of X-rays on the object, a shutter arranged around an X-ray irradiation axis for regulating an X-ray irradiation region on which the beam of X-rays is irradiated through the object, and a visual indicator unit arranged on the shutter for movement together with the shutter, the visual indicator unit being designed to visually indicate the X-ray irradiation region. In the X-ray device, the X-ray irradiation region is visually indicated by laser light without having to use a lamp otherwise provided between the X-ray tube and the shutter.

Abstract: We propose to shape the leaf by the use of electro-chemical machining (ECM). ECM is a technique by which a blank is suspended within a mould, with a small gap therebetween. A conductive fluid is caused to flow through the gap, and a large electrical current is passed from the mould to the blank. The blank steadily erodes, dissolving into the fluid. The fluid should not provoke a reaction from the material of the blank, such as a surface oxide. Sodium Chloride solution is a common choice. The current that is passed can, if desired, be controlled to a profile that will affect the manner of erosion. Thus, the current profile can be a steady on/off current, or it can be pulsed. One known arrangement is for the current to rise to a peak, then fall to zero, followed by a brief reverse flow.

Abstract: A method for fabricating a collimator assembly is provided. The collimator assembly includes a first collimator grid having a first surface and an opposing second surface, wherein the first collimator grid defines a plurality of cells. Each cell of the plurality of cells is aligned in a first direction and extends between the first surface and the second surface. The method includes coupling a reinforcing layer to the first collimator grid such that the reinforcing layer extends substantially perpendicular to the first direction.

Abstract: A multi-leaf collimator includes a number of independently adjustable leaves. Adjacent leaves overlap to prevent an incident beam of radiation from passing through a gap between them. The overlapping portions of the leaves are made of a first material, while the non-overlapping portions of the leaves are made of a second, different material.

Abstract: A method and system for performing fluoroscopic imaging of a subject has high temporal and spatial resolution in a center portion of the captured dynamic images. The system provides for reduced X-ray dose to the patient associated with that part of the X-ray beam associated with a peripheral portion of the captured images although temporal, and in some embodiments spatial, resolution is reduced in the peripheral portion of the image. The system uses a rotating collimator to produce an X-ray beam having narrow wing portions associated with the peripheral portions of the image, and a broader central region associated with the high resolution center portion of the images.

Abstract: A collimator blade aligning device, a collimator blade aligning apparatus and a method for producing a radiation collimator are disclosed. For the purpose of particularly simple and accurate alignment of the collimator blades, at least one embodiment provides that the collimator blade aligning device can be rotated between a positioning position and aligning position, a first thickness assigned to the positioning position being smaller than, and a second thickness assigned to the aligning position being equal to the blade spacing.

Abstract: The angle of each collimator plate with respect to an X ray focal point is determined by fitting the collimator plate in grooves formed in upper and lower supports each having an integral structure. In addition, the warpage of each collimator plate is corrected and its flatness is maintained by fitting the periphery of the collimator plate which is on the X ray detector side in a corresponding groove of an abutment plate provided on the X ray detection surface side of the upper and lower supports. Furthermore, each collimator plate is supported by the corresponding grooves of the upper and lower supports and the corresponding groove of the abutment plate on at least three sides.

Abstract: A technique for establishing texture metrics and bone mineral density (BMD) within an anatomical region of interest. A digital imaging system is used to acquire a standard digital X-ray image with a wide field of view. The standard digital X-ray image is used to guide the imaging system to obtain an image of a region of interest. The standard digital X-ray image is used to calculate various texture metrics, such as a length of a fracture. A dual-energy digital X-ray image of the region of interest is acquired. The dual-energy digital X-ray image is corrected for scatter. The BMD of the region of interest may be established from the scatter-corrected dual-energy digital X-ray image. The BMD, the texture metrics, and/or the scatter-corrected dual-energy X-ray image may be displayed on the standard digital X-ray image.

Abstract: An X-ray imaging apparatus includes an X-ray collimator control unit which controls an X-ray collimator shape, an X-ray irradiation unit which irradiates X-rays in accordance with the X-ray collimator shape, an X-ray imaging unit which receives the irradiated X-rays and acquires a radiograph, a perpendicularity determination unit which determines, on the basis of the comparison between the X-ray collimator shape and the radiograph, whether the X-ray irradiation direction of the X-ray irradiation unit is perpendicular to a light-receiving surface by which the X-ray imaging unit receives the X-rays, and an irradiation control unit which controls X-ray irradiation by the X-ray irradiation unit on the basis of the determination result obtained by the perpendicularity determination unit.

Abstract: Linear scanning x-ray apparatus generates a collimated fan beam which is moved together with a detector relative to a subject to generate a composite x-ray image of the subject. An adjustable collimator varies the width of the imaging beam in the scan direction. A control system responds to adjustment of the collimator to combine output signals of groups of two or more pixels in the detector, in order to optimize the contrast resolution of the image signals for a given spatial resolution. The invention provides a collimator for use in the apparatus.

Abstract: Systems, methods and apparatus are provided through which in some embodiments, a wrap-around capture device of an X-ray collimator frame limits movement of an X-ray tube mounting bracket away from the X-ray collimator. In some embodiments, a C-shaped passive capture device is attached or mounted on the wrap-around capture device, having a portion that is positioned in between the wrap-around capture device and the X-ray collimator frame, which further limits movement of the X-ray tube mounting bracket.

Abstract: Certain exemplary embodiments of the present invention comprise a device comprising a cast computed-tomography collimator descended from a lithographically-derived micro-machined metallic foil stack lamination mold. Certain exemplary embodiments of the present invention comprise a method comprising filling a mold having a stacked plurality of micro-machined metallic foil layers with a first casting material to form a first cast product; demolding the first cast product from the mold; filling the first cast product with a second casting material to form a cast computed-tomography collimator; and demolding the cast computed-tomography collimator from the first cast product. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. This abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A collimator for adjusting an X-ray beam includes: an up-and-down adjustment mechanism; a left-and-right adjustment mechanism, a supporting member; and an adjusting plate connected with the supporting member. The up-and-down adjustment mechanism comprises first rotating nuts, up-and-down moving leading screws threadedly connected with the first rotating nuts, and upper and lower sliding stops located in the supporting member. Each of the leading screws is connected with the upper and lower sliding stops to drive the upper and lower sliding stops, respectively, to vertically move. The left-and-right adjustment mechanism comprises second rotating nuts, horizontally moving leading screws connected with second rotating nuts, and left and right sliding stops located in the supporting member. Each of the horizontally moving leading screws are connected with the left and right sliding stops to drive the left and right sliding stops, respectively, to horizontally move.

Abstract: A system and method are provided for a high resolution radiation treatment system which provide for projecting a field of radiation energy at targeted patient tissue. The system uses a multi-leaf collimator, which is positioned such that a significant clearance is provided between the multi-leaf collimator and the isocenter plane where the targeted tissue is located. The leaves of the multi-leaf collimator are designed to provide for high step resolution in the projected radiation energy shape. Additionally, an embodiment of the system and method herein can provide for a high step resolution in the projected radiation energy shape, and for a dose calculation matrix which has matrix units which coincide with the high step resolution in the projected radiation shape.

Abstract: Reduced source spacing for multi-source, multi-detector X-ray imaging systems is provided by allowing channels within an X-ray collimator to intersect within the body of the collimator. As a result, the channels are not independent, and the source spacing can be significantly reduced. Although such collimators have a much more “open” structure than conventional collimators having independent channels, they can still provide efficient collimation performance (e.g., predicted leakage <5%). Several high attenuation layers having through holes and stacked together can provide collimators according to the invention, where the through holes combine to form the intersecting channels.

Abstract: Systems and methods for highly collimated and temporally variable X-ray beams. Disclosed herein is a system for producing a collimated X-ray beam, the system including one or more distributed electron sources configured to produce electron beams, one or more X-ray production targets configured to receive the electron beams and to generate X-ray beams at X-ray focal spots, X-ray optics configured to collect the X-ray beams from the X-ray focal spots, wherein the X-rays optics are configured to focus the X-ray beams to a single virtual focal spot, and an X-ray collimator configured to collimate the X-ray beams from the virtual focal spot to generate the collimated X-ray beam.

Abstract: The inspection methods and systems of the present invention are mobile, rapidly deployable, and capable of scanning a wide variety of receptacles cost-effectively and accurately on uneven surfaces. The present invention is directed toward a portable inspection system for generating an image representation of target objects using a radiation source, comprising a mobile vehicle, a detector array physically attached to a movable boom having a proximal end and a distal end. The proximal end is physically attached to the vehicle. The invention also comprises at least one source of radiation. The radiation source is fixedly attached to the distal end of the boom, wherein the image is generated by introducing the target objects in between the radiation source and the detector array, exposing the objects to radiation, and detecting radiation.

Abstract: An energy filter device for beams which are used in the course of ion beam therapy, wherein at least one passive modulator is provided. The modulator can comprise a scattering film for the beams and a collimator with an opening for controlling the beams, or a magnetic filter and an absorber, or a nonlinear filter and an apparatus for clipping the intensity of individual energy levels of the beams.

Abstract: The invention relates to a mounting device for mounting a beam manipulating device of an X-ray apparatus to a radiation source of the X-ray apparatus, said mounting device comprising a first mounting flange (10) associated with the radiation source, a second mounting flange (20) associated with the beam manipulating device, and fastening means (60) for fixing the first mounting flange (10) and the second mounting flange (20) to each other. It is an object of the invention to facilitate the alignment of the X-ray beam manipulating device with respect to an X-ray beam path or an X-ray beam focus of the radiation source. To achieve this, the alignment means (30) are adapted to be fastened to the first mounting flange (10), the first mounting flange having a first reference surface (31) which is in a predetermined spaced relationship with respect to the X-ray beam path. The first reference surface (31) corresponds with a second reference surface (34) of the second mounting flange (20).

Abstract: Method and apparatus for varying the hole length of a parallel hole collimator, provides a variably configurable compound collimator for use in nuclear imaging. The collimator has a plurality of substantially parallel oriented collimator cores configured for transition between a contracted configuration and an expanded configuration, wherein a gap space between said collimator cores is greater in the expanded configuration than the contracted configuration. The maximum gap space is designed to prevent photons from one hole in the collimator from reaching the detector proximate an adjacent hole of the collimator.

Abstract: A scanning device for providing a radiation scan to an article is disclosed. The scanning device includes a housing, a transport system and a radiation attenuation system. The housing has a entrance port and an exit port and encloses a radiation analysis unit. The transport system is configured to move the article from the entrance port, through the housing and to the exit port. The radiation attenuation system is supported at one of the entrance port and the exit port. The radiation attenuation system includes at least one substantially rigid panel rotatable relative to the housing and a counter balance coupled to the panel to at least partially offset the weight of the panel.

Abstract: A method for developing a multi-focus primary collimator is described. The method includes extending a first beam from a first source via a collimator block to a first detector and determining a size of the first beam.

Abstract: Certain exemplary embodiments of the present invention comprise a cast collimator descended from a stack lamination mold, said mold comprising a plurality of metallic foils. Certain embodiments of the present invention comprise a method comprising filling a mold having a stacked plurality of micro-machined metallic foil layers with a first casting material to form a first cast product; demolding the first cast product from the mold; filling the first cast product with a second casting material to form a cast collimator; and demolding the cast collimator from the first cast product. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. This abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Abstract: A collimator that formed from a plurality of metal layers that are shaped by use of lithographic techniques in specific shapes. The formed metal layers are stacked and aligned together and then connected together to form the collimator.

Abstract: A secondary collimator for an X-ray scattering device with horizontal plates and vertical plates arranged perpendicular thereto, the vertical plates being arranged parallel to one another and being inclined by a pre-determinable scattering angle to a transmission direction of an X-ray beam, and the horizontal plates being aligned fan-shaped onto a single point, namely to the X-ray source, and the horizontal plates with the vertical plates forming a rectangular grid with the vertical plates and being combined to form a collimator unit. Moreover, the invention relates to an X-ray scattering device for baggage check with an X-ray source, with a primary collimator which only lets through a fan beam, with a secondary collimator for projecting an area of an item of luggage and with a scattering detector, the secondary collimator being arranged between the item of luggage to be examined and the scattering detector and being developed as mentioned above.

Abstract: A detector apparatus is disclosed that includes a housing and a multilayer disposed within the housing. The multilayer defining a leading edge and a trailing edge and is adapted to interact with a plurality of high-energy photons, impingent from the leading edge, to permit passage of photons of at least one selected energy. The multilayer is secured to a first securement adjacent to the leading edge. The multilayer is secured to a second securement bracket adjacent to the trailing edge. At least one detector is disposed adjacent to the trailing edge of the multilayer to detect the impingent high-energy photons. An adjustment mechanism operatively connects to the second securement bracket to adjust the position of the second securement bracket, thereby altering an angular position of the multilayer.

Abstract: A multi-leaf collimator includes a number of independently adjustable leaves. Adjacent leaves overlap to prevent an incident beam of radiation from passing through a gap between them. The overlapping portions of the leaves are made of a first material, while the non-overlapping portions of the leaves are made of a second, different material.

Abstract: An X-ray fluorescence analyzer device comprises an X-ray source and a sample window. Between the X-ray source and the sample window there are a collimator plate with a plurality of microscopic pores and an annular plate comprising material essentially opaque to X-rays. The annular plate defines an area transparent to X-rays. The pores in said collimator plate let through collimated X-rays radiated by said X-ray source towards said sample window. The area transparent to X-rays in said annular plate spatially limits in a transverse direction a beam of X-rays radiated by said X-ray source towards said sample window.

Abstract: A positioning system for radiation therapy comprises a patient positioner drive unit for moving a patient positioner supporting a patient, a snout drive unit for rotating a snout including a collimator set therein, and a processing unit for controlling the snout drive unit and the patient positioner drive unit such that the positioning of the patient is performed by moving the patient positioner supporting the patient after the positioning of the collimator has been performed by rotating the snout including the collimator set therein. Exposure of the patient to X-rays irradiated for the positioning can be reduced.

Abstract: Disclosed are systems and methods for obtaining stereoscopic x-ray images. The method includes taking two digital x-ray views of the same object from differing positions. The included angle between the axes of the x-rays for each position generally coincides with that formed by a pair of eyes viewing the object, though larger angles can be used. The x-rays can be taken by two x-ray generators within a single housing or within separate but attached housings. The generators are spaced apart and aimed at the object to form the appropriate angle. Care is taken not to move the object. Preferably, the x-ray generators have dual collimators to take the views. In this case, the time between taking the two x-rays need only be as long as the image capture time of the sensor being used, which lessens the chance of the object moving.

Abstract: A collimator is to be provided which permits the reduction of size without using any special material and without sacrificing an aperture. To this end, the collimator comprises: a pair of first plate members each having X-ray absorbability, movable in a direction parallel to a surface thereof, and defining an X-ray passing aperture by a spacing between respective mutually opposed end faces; and a pair of second plate members each having X-ray absorbability, the second block members, in order to block other X-rays than the X-ray passing through the aperture, being connected at respective one ends by hinges to end portions of the pair of first plate members opposite to the mutually opposed end faces of the first plate members and being supported at respective opposite ends so as to be movable obliquely with respect to the moving direction of the first plate members with movement of the first plate members.

Abstract: A shielding arrangement for an x-ray apparatus, preferably for mammography examination is disclosed, and comprises at least an x-ray source, a collimator arrangement and a detector assembly, whereby the collimator is arranged between the x-ray source and the detector assembly and through which x-rays pass. The shielding arrangement, at least partly made of x-ray blocking material and provided for blocking, scattering and/or reflecting x-rays is arranged, at least partly, in a space between the x-ray source and collimator.

Abstract: A method of manufacturing a collimator mandrel having variable attenuation characteristics is presented. The manufacturing process includes the placement of a layer of attenuating material on a core of base material. The layer of attenuating material is relatively thin and varies in thickness circumferentially around the core. The collimator mandrel may be manufactured by placing a cast about a core of non-attenuating material, filling a void between the cast and the core with an attenuating material, allowing the material to cure, and removing the cast from the assembly.