EP3120364A1

EP3120364A1 - Slot aperture for applications in radiography

Info

Publication number: EP3120364A1
Application number: EP15711190.7A
Authority: EP
Inventors: Kurt Osterloh; Uwe Zscherpel; Uwe Ewert; Norma Wrobel
Original assignee: Bundesministerium fuer Wirtschaft und Technologie
Current assignee: Bundesministerium fuer Wirtschaft und Technologie
Priority date: 2014-03-20
Filing date: 2015-03-20
Publication date: 2017-01-25
Also published as: US20170084358A1; WO2015140325A1; DE102014103833B3

Abstract

The invention relates to a slot aperture, in particular for an imaging device which is suitable to delimit high-energy radiation originating from a radiation source, in particular x-rays and/or synchrotron radiation. The invention further relates to a production method for said multiple slot aperture and to a use thereof for the imaging representation of a test element. The slot aperture comprises: a first slot block and a second slot block, wherein the first and the second slot block comprises a radiation-absorbing part and at least one radiation-transparent slot and the first and the second slot block can be arranged in relation to each other such that, in a first position, the at least one slot arranged in the first slot block is continued in exactly one corresponding slot arranged in the second slot block, such that a beam extending through the first slot of the first slot block passes unimpeded through the second slot block and, in a second position, the slot of the first slot block points to a region of the second slot block that is free of slots, such that a beam extending through the first slot of the first slot block strikes the region of the second slot block that is adjacent to the corresponding slot, and thus does not penetrate the second slot block.

Description

Slit diaphragm for radiography applications

The present invention relates to a slit, a device for operating a slit and a method for producing a slit for

Applications in radiography.

In particular, the invention relates to a multiple slot diaphragm, the for

Applications based on the Compton backscatter radiography is adjusted.

[0003] DE 10 2005 029 674 B4 and EP 2 333 786 B 1 describe a slit diaphragm for limiting the radiation emanating from a radiation source. Such apertures are particularly interesting for the study of unknown objects that are active

(Gamma radiation) or passively (backscattered) emitting high-energy radiation. A practically significant examination technique uses non-elastically backscattered X-ray photons for imaging (radiography).

The corresponding radiography method is called Compton

Reverse scattering technique called. Objects that are transparent to X-rays seem to "shine" through the backscattered radiation. This applies above all to organic materials and elements with a low atomic number as a function of their sequence in the periodic table. X-rays are mainly absorbed by elements of high atomic number, for example heavy metals, so that the here occurring

Scattered radiation, if detectable at all, has a very low intensity.

This circumstance can be used for the generation of comparatively high-resolution images, for example for the purposes of a security check or for

Non-destructive testing if a custom aperture is used.

The aforementioned screens are comparatively massive according to the requirements to be imposed on them. Measurement arrangements, such as, for example, imaging devices constructed according to the pinhole camera principle, which comprise a slit diaphragm, can therefore be used only to a limited extent, if at all, on a mobile device. In addition, for the production of the

Slit diaphragm suitable method due to the high demands on the quality of internal surfaces of the panel typically consuming and costly. Consequently, the following tasks arise:

1. On the one hand, to image a radiant body as sharp as possible and / or

on the other hand, by means of backscatter technique to gain image information about the structure of an unknown object that is not detectable with a single beam;

2. the imaging surface by using a novel aperture (the here

proposed multiple slot diaphragm), and suitable methods for

To provide the diaphragm;

3. a compact (lightweight) and yet reliable dimming

To provide diaphragm device, the slot width is adjustable;

4. provide a device for mechanical adjustment of the slot width

5. to prevent the parallel passage of rays through the aperture and a

Overlay multiple recordings to prevent.

Against this background, according to claim 1 is a slit, according to claim 16, a manufacturing method for a slit and according to claim 21, the use of the proposed slit for imaging by means of high-energy radiation, according to claim 22 an image forming method

With the aid of said slit diaphragm and according to claim 24 an imaging

Device comprising said slotted diaphragm proposed. Further advantageous embodiments, details and features of the present invention will become apparent from the dependent claims, the description and the embodiments.

According to a first embodiment, a slit diaphragm, in particular proposed for an imaging device, which is suitable, emanating from a radiation source high-energy radiation, in particular X-ray and / or

Synchrotron radiation, comprising a first slit block and a second slit block, wherein the first and the second slit block comprises a radiation-absorbing member and at least one radiation-transmissive slot and the first and the second slit block are mutually arranged so that in a first position of the first slot block arranged at least one slot in exactly one arranged in the second slot block corresponding slot continues so that a passing through the first slot of the first slot block beam passes through the second slot block unhindered, and in a second position, the slot of the first slot block on one of

Slots free area of the second slot block points, so one through the first slot of the first slit block beam strikes a region adjacent to the corresponding slot portion of the second slit block and thus does not penetrate the second slit block. Thus, in the first block, the entire passageway for the passing beam is bounded from the top to the second from below.

Advantages of this embodiment consist on the one hand in a simplified production of a slit diaphragm with a plurality of slots (multiple slit), primarily in a simple construction of a diaphragm, which comprises two mutually displaceable and at least one slot having plates. The resulting panel is much lighter, requires less material than known panels and is therefore easier to transport and / or mobile. According to preferred embodiments, the slit comprises at least one, for example 3, typically 5 or more radiation-transmissive slits. An advantage of having multiple slots results from a wider field of view for the shots compared to the single slot. The resolution is improved by a narrower gap at the expense of the width of the field of view. Depending on the given measurement situation or task, it is thus possible to choose between an increased image sharpness with a reduced slot width and an increasing width of the field of view (image width) with an increased slot width (wider aperture).

According to a further embodiment, the second position of the arrangement of the two slot blocks as proposed corresponds to a parallel displacement of the slots of the first slot block to those of the second slot block.

This results in advantages for the reproducibility of the aperture setting and the design of a device by means of which such a shift is achieved.

According to another embodiment has an adjacent

Surface area between the first and an adjacent second slot of the second slot block at least one shape resulting from a projection of the

Cross-sectional area of the first slot of the first slot block on the first

Slot block facing surface of the second slot block results.

This advantageously results in the possibility of opening without

Shearing of the beam channel and an error-free enlargement or narrowing of the effective aperture width.

According to a further embodiment, a slot of the proposed slotted diaphragm at least two mutually opposite walls of at least partially identical shape. The said two walls are opposite each other within the slot block.

Advantageously, the two walls thus form a section-wise plane-parallel enclosure of a beam, so that a on one side of the slot block entering the slot beam bundle the slot block on the other,

leave the opposite side unattenuated.

According to another embodiment, at least one of the walls of the proposed slit diaphragm comprises a metal sheet.

Advantages result from the simplified production of the walls, in particular because sheets can be comparatively easily bring in an identical form.

According to a further embodiment, a slit is proposed, wherein the sheet is selected from: aluminum, bronze, iron, copper, brass, nickel, steel, titanium, tungsten or an alloy comprising at least one of the elements: Al, Be, Pb, Cu, Cr, Fe, Ni, Sn, Ti, W, Zn. If the thickness of the diaphragm was a thin sheet, the choice of material for the sheet would be less important "Main load" of the shielding by the filling material between the

Cover plates taken over the slots.

Advantages of these elements include the availability of sheets, comprising pure metals or alloys of these elements and the respective atomic number of these elements, which justifies their suitability as an absorber of high-energy radiation. By selecting the materials and in the interest of a portable embodiment of the diaphragm, the slit diaphragm is adapted for use with high-energy radiation in the range of 50 to 1000 keV, in particular in the range up to 500 keV, preferably for radiation energies below 400 keV.

According to a further embodiment, a slit is proposed, wherein the radiation-absorbing part comprises lead, which is arranged between the walls of adjacent slots.

Advantages of lead as an absorber of high-energy radiation are possible. Also, a lead sheet can be formed very easily.

According to a further embodiment, a slit diaphragm is proposed, wherein a first wall a first approximately of the thickness of the maximum possible Gap width comprises sheet metal, which has a higher absorption capacity for the high-energy radiation, as a sheet, which is covered by a second wall.

Advantages of this embodiment result from the fact that when closing the slit one of the two walls of the slot of a slit block of

unweakened radiation is exposed by passing through the corresponding slot in the opposite slot block beam. The described embodiment ensures a reliable shielding effect, despite the barrier being only half as thick in the region of the beam and created by the slit diaphragm material of only one slit block.

According to a further embodiment, a slit is proposed, wherein a thickness and / or a profile of the first sheet of the slot in the first slit block has at least one thickness and / or a profile of the corresponding slot in the second slit block, and a thickness and / or a profile of the second sheet of the slot in the second slot block has at least one thickness and / or a profile of the corresponding slot in the first slot block.

Advantages result in particular for an adjustable quality of the beam projection or imaging, i. either high beam penetration dose at the expense of sharpness or a sharp image at the expense of intensity, similar to the aperture setting on a normal camera, where it comes to depth of field.

According to another embodiment, a slit is proposed, wherein at least two of the slots of the same slit block an identical

Have cross-sectional area and / or shape.

The advantages of this embodiment correspond to the aforementioned.

In particular, the arrangement of self-similar slots - nothing else is to describe the embodiment described above - allows a high magnified

Imaging surface.

According to another embodiment, a slit is proposed, wherein planes defined by the slits in the first slit block intersect each other in a line lying outside the first slit block on a side facing the second slit block.

For more effective shielding of high-energy radiation in the slot area at (partially) closed position by appropriate displacement of the front and rear half of the panel against each other is the lining a denser material than proposed that of the remaining visor body. Any beam that does not pass through one of the slots is shielded by the aperture in its entire layer thickness. The one which, in a closed position, passes through the front half of the diaphragm through a slit, can only be shielded by the advanced part of the rear (see hatched areas in Fig. 6). To compensate for the missing layer thickness to the total aperture thickness, a denser material in this area is proposed. For example, if the visor body is made of copper or brass, then tungsten is a suitable material for this field.

According to a further embodiment, an imaging device comprising a slit diaphragm is proposed, wherein the high energy radiation in the range of 50 keV to 20 MeV (including high energy gamma emitters such as ⁶⁰ Co etc.), for example in the range 150 keV to 1000 keV, typically in the range 100 keV to 450 keV.

Advantageously, the energy of high energy gamma emitters, such as

for example, those of 60 Co, 13V Cs, 192 Ir, etc. within the specified range. Of the

Energy range of commercial X-ray tubes is typically between 100 keV and 450 keV, so that the imaging device is suitable for use with commercially available x-ray tubes and in their concrete structural design (construction) can be adapted to the particular measurement situation. The relevant one is also advantageous

Qualified personnel involved in the recording of images of the objects concerned are qualified to handle the standard X-ray tubes or radiation sources.

According to a further embodiment, an imaging device is proposed, wherein a shielding thickness of the slit diaphragm is adapted to an energy range of high-energy radiation up to about 300 keV. The area denoted by "ca." Should be 300 keV + 50 keV According to a practical embodiment, only 1/5 of the shielding thickness of the shielding thickness required therefor is required compared to a high-energy radiation of 1 MeV energy.

It follows that it is advantageous that e.g. when using tungsten as a shielding material, the wall thickness of the imaging device from 5 cm to 1 cm

is reducible. This leads to a weight reduction of the imaging device by 80% regardless of the shielding material. As can be seen, this weight reduction is considerable, and greatly improves the transportability and mobile applicability of the device. For example, a reduced to about 30 kg total mass imaging device compared to a weighing 150 kg device may well be handled by only a single person. As an alternative to a scale reduction remains the original selected width of the slit diaphragm. The weight reduction is thus achieved solely by reducing the wall thickness, wherein the known from the thick-walled embodiment ago total receiving geometry is maintained in principle.

According to another embodiment, a preferred range of the slot width adjustment is between 1 and 7 mm. Depending on the measurement situation and the target position, a person skilled in the art weighs between an increased image sharpness with a small slit or small slit and a desired maximum width (height) of the image (wide opening or wider slit). A preferred slot width can be varied, for example, between 0.5 mm and 10 mm. Likewise, the at least one gap (or synchronously all gaps) may be fixed relative to one another by a relative movement of the first slot block and the second slot block between 0.75 mm and 8 mm or between 1 mm and 7 mm, optionally also between 2 mm and 5 mm be set. In this case, a precision of the adjustment is typically + 0.01 mm or + 0.1 mm, for example + 0.25 mm. Any necessary drives for automatically adjusting the desired gap width, for example a stepper motor (e.g., toothed belt drive stepper motor), will be apparent to those skilled in the art. In addition, via the suitable dimensioning of the gears 5, 7 and 8 or of the chain 6 used in the gear, the slot width can also be adjusted manually with the required precision, for example by means of a crank, which is suitably connectable to a drive stage. From a set angle of the crank results - with previous calibration - the respective gap width.

According to a further embodiment, a production method for a high-energy radiation slit as described above is proposed, which comprises the following steps:

- forming at least two sheets on an output molding;

equidistantly connecting two sheets each to each other such that the interconnected sheets form a channel, the channel having a first open end and a second open end opposite thereto;

- arranging and aligning the channel in a mold;

- filling the mold with a lead-containing melt such that the channel is not filled with the melt;

Demolding of a casting body obtained in the casting mold comprising the channel. An advantage of this manufacturing method over known production method is that a predetermined slot shape of a slot block can be generated to some extent additive. It is considerably more complicated to produce a slot with the required properties (eg plane parallelism of wall sections, surface quality, etc.) by machining processes in a solid material, than to encase the melt of the solid material, essentially a slot formed with two metal sheets ,

According to a further embodiment, a manufacturing method for a high-energy radiation slit as described above is proposed, which comprises the step of "trimming the cast body into a slit block".

Advantages of this embodiment result from the fact that with only a few working steps burr-related burrs and / or support structures or

Excess material can be removed.

According to a further embodiment, the proposed

Manufacturing method, the step: - adjusting and aligning a first and a second slit block, so that in a first position of the slit blocks to each other, arranged in the first slit block at least one slot in exactly one arranged in the second slit block corresponding slot continues so that one through the first Slit of the first slit block beam passes unhindered through the second slit block, and in a second position, the slot of the first slit block on a slot-free area of the second slit block, so that a passing through the first slot of the first slit block beam on a to

corresponding slot adjacent area of the second slot block meets and thus does not penetrate the second slot block.

Advantages of this embodiment result from the assembly of the slit diaphragm from the two essential constituent elements: the first and the second slit block.

According to a further embodiment, the proposed

Manufacturing method, the step: - Providing a drive for a gradual change between the first and the second position, so that a resulting thickness of the first and the second slit block passing beam is adjustable as needed.

Advantages result from the so achievable precision of the setting Cover. In particular, in the case of a narrowing of the slot width, part of the radiation is shielded only by the barrier layer of one of the two blocks, but all the other non-passing components are shielded by the material of both diaphragm parts. Therefore, this barrier layer can be made of a more absorbent material. One possible combination of materials may be, for example, copper or brass for the visor body and tungsten for the barrier layer.

According to a further embodiment, the proposed

Manufacturing method, the step: - Arranging an image pickup unit on one side of a slit block, so that a falling through the slit diaphragm beam hits a detecting surface of the image pickup unit.

Typical advantages of this embodiment relate to the mobile applicability of the device for imaging objects of interest. Due to the independence of the operation of a portable slit camera of the

Einstrahlgeometrie with the X-ray emitters succeed recordings that were not possible with conventional X-ray backscattering. The backscatter behavior of individual material layers in the object can be controlled by targeted irradiation. Thus, it is possible to represent radiopaque components, regardless of a laboratory environment as a silhouette against a bright background. This is particularly important for applications with a safety background.

According to another embodiment, the use of a

For example, slit diaphragm described above for imaging imaging of a specimen proposed by exposure to high-energy radiation, wherein a radiation source of high-energy radiation, a test specimen and the slit are arranged to each other so that the specimen backscattered portions of

high-energy radiation through the slit on an imaging unit and / or on a detector meet.

Advantages of using the slit diaphragm described result from the already described advantages of the proposed device. They relate in particular to the possibility of comparatively clear imaging by means of Compton backscattering of a little absorbing component against the background of a strongly absorbing one

Component. Provided a separate illumination of the area behind the strongly absorbing component in the object by corresponding KoUimierung an incident laterally obliquely to the direction of the camera into the object X-ray radiation. Thus, a radiant background is created, in front of which an absorbent member then

silhouetted silhouetted. Such a mapping geometry is with no other

X-ray backscatter achievable According to a further embodiment, an image forming method for non-destructive material testing of an object with high-energy radiation, in particular with X-ray, gamma and / or synchrotron radiation is proposed. The image forming method comprises the steps of: providing an imaging device comprising a slit of at least one of the above embodiments and a detector; Arranging the imaging device and the object, so that emanating from the object and / or backscattered high-energy radiation through the

Slit diaphragm falls on the detector of the imaging device; and adjusting a slit width of the slit of the imaging device with respect to

Radiation intensity, so that at the set slit width suitable for generating an image portion of the object from the object and / or backscattered

high-energy radiation is directed to the detector.

Advantages of this embodiment are achieved by satisfying a need for reliable non-destructive testing methods, for example in the field of composite materials, which provide the advantages of high energy radiation imaging. As described, image acquisition can take place with an adapted mobile device on site. Applications range from vehicle construction (automotive, aircraft, rail vehicles) through the construction and monitoring of wind turbines to applications in the field of the protection of art and cultural goods (restoration) and also relate directly

safety aspects (storage of dangerous goods, customs control).

According to a specific embodiment, the image forming method comprises inspecting a composite material, wherein the non-destructive material testing permits evidence of inclusion and / or inhomogeneity in the composite material.

Advantageously, inclusions and / or inhomogeneities provide particularly good detectable signals, so that such structures, which are particularly critical for a failure behavior, can be detected beyond doubt.

According to a further embodiment, an imaging device comprising a slit diaphragm with at least one radiation-transmissive slit and a detector is proposed, wherein a high-energy radiation, in particular X-ray, gamma and / or synchrotron radiation with respect to a radiation intensity by means of an adjustable slit width of the at least one radiation-permeable slit is adaptable so that emanating from an active radiating object and / or backscattered by an unknown object high-energy radiation at the set

Slot width a suitable for generating an image proportion of high-energy Radiation passes through the slit on the detector, wherein the slit comprises a first slit block and a second slit block, each one

Radiation-absorbing part and at least one radiation-transmissive slot and the first and the second slot block are mutually arranged so that in a first position of the arranged in the first slot block at least one slot in exactly one arranged in the second slot block corresponding slot continues so that one through the first Slit of the first slit block beam passes unhindered through the second slit block, and in a second position, the slot of the first

Slots block on a slot-free area of the second slit block, so that a running through the first slot of the first slit block beam hits a region adjacent to the corresponding slot portion of the second slit block and the beam thus does not penetrate the second slit block. So in the first

Slit block the entire passageway for the passing beam from one side, for example from above (or for example from the left), and limited in the second from an opposite side, for example from below (or for example from the right).

Advantages of this embodiment consist on the one hand in a simplified production of a slit diaphragm with a plurality of slots (multiple slit), primarily in a simple construction of a diaphragm comprising two mutually displaceable and at least one slot having plates. The resulting panel is much lighter, requires less material than known panels and is therefore easier to transport and / or mobile. According to preferred embodiments, the slit comprises at least one, for example 3, typically 5 or more radiation-transmissive slits. An advantage of having multiple slots results from a wider field of view for the shots compared to the single slot. The resolution is improved by a narrower gap at the expense of the width of the field of view. Depending on the given measurement situation or task, it is thus possible to choose between an increased image sharpness with a reduced slot width and an increasing width of the field of view (image width) with an increased slot width (wider aperture).

According to another embodiment, a slot of the proposed imaging device at least two opposing walls of at least partially identical shape. The said two walls are opposite each other within the respective slot block.

Advantageously, the two walls thus form a section-wise plane-parallel enclosure of a beam, so that one on one side of the slit block entering the slot beam can leave the slot block on the other, opposite side unattenuated and strikes the detector unattenuated, whereby a high image quality can be achieved.

According to further embodiments, it is proposed to manufacture at least one of the slot blocks described with the aid of an alternative

Manufacturing process, wherein the manufacturing process is based on a 3-D printing process. A suitable 3D printing process typically involves layer-by-layer sintering of a fine particulate metal powder, for example by means of a laser beam, layered according to a particular cross-section of the designed one

Slot block is passed over a metal powder bed. For example, lead-based powders can readily be formed into complex spatial shapes by sintering. Another suitable 3D printing process can be realized by means of a metal wire, analogously to established 3D fusion printing processes with a plastic strand, e.g. a wire comprising a lead-containing alloy. 3D printing processes, which are predestined for the production of complex spatial structures, are particularly suitable for the production of slits in the slotted plate, which are present as defined cavities (undercuts) in solid material. For both of the 3D printing methods described here, with regard to the materials usable for 3D printing, it is possible to build on know-how from the field of production of solders, in particular solder pastes, and corresponding metal powders.

The embodiments described above can be combined with each other as desired.

The accompanying drawings illustrate embodiments and together with the description serve to explain the principles of the invention. The elements of the drawings are relative to one another and not necessarily to scale.

Like reference numerals designate corresponding parts accordingly. Showing:

1A is a conventional arrangement according to the prior art

Image recording unit for examining an object by means of

Compton backscatter over a "scan with a

Pencil beam "

Fig. 1B, the principle of the here tracked image of an object by means of

Compton backscatter over total coverage

(Field illumination) of the examined object

Fig. 2 is a scheme for the design of one of several materials composite visor body, starting from a solid visor body; the return of the shapes of different slits in a multi-slit to a common initial shape;

Steps from a fixed multiple slot to the variably adjustable version;

Semi-apertures in top view with one (of several possible) slits at the front (black) and rear (gray) in the "closed" position (left) and in the open position (right);

Half-aperture simplified shape for a mount in which steeper incident radiation is absorbed by a corresponding frame. The closed position of the panels is shown in the left part of the picture, the open position, after a corresponding

Downward movement of the right part of the body is shown in the right part of the picture; the use of materials of construction of different poets for more effective shielding in the closed part of the beam path; the installation of a trapezoidal diaphragm body with its narrow side to the object, so that the rays falling through the diaphragm in front of the diaphragm in a vertical axis intersect; a side view of a mechanical propulsion for

Slot width adjustment of a multi-slot shutter;

Top view on a possible mount one

Multi-slot shutter in a housing that can be installed in a "lead castle" with lead seals ("dovetails");

Bottom view on the drive of the slot setting with

Adjusting wheels, the axes of the propulsion linkage and their connection via a drive chain shown in Figure 10; 12 is a perspective view of a slit diaphragm for a reduced mass embodiment, with only one slot being shown by way of example.

In particular, Fig. 1A shows an arrangement typically used in the prior art for examining an unknown object by means of Compton backscattering. X-ray radiation emanating from an X-ray tube 100 used as a radiation source is directed through a pinhole 200 onto the object 300 to be examined. The X-radiation is directed to the object 300 as a "lead pencil beam".

Typically, the object (see vertical arrow on the left in Fig. 1A) by means of

Scanned point lighting. Compton radiation 400 backscattered by the surface, if necessary also from the depth of the object, is detected by a detection unit 500 and converted into image information (for example by means of suitable methods)

X-ray fluorescence film, array detector, etc.). A shield 600 serves to protect against external exposure / radiation.

In contrast, according to the approach followed here, as shown in FIG. 1B in an overview, using a slit 220, the X-radiation 400 backscattered by the object can be used directly for imaging. The

Slit diaphragm 220 is part of a camera 700, which includes a shield 600 enclosing the detection unit 500.

In Fig. 2, the transition from a solid diaphragm body is schematically shown to a composite of several materials visor body. In this case, the partial image a) shows the course of three slot progressions with their common central axis (dot-dashed line). The implementation of this concept in a solid diaphragm body has been described previously (EP 2333786 Bl). According to the invention, an absorbing diaphragm body does not have to surround the beam path of the high-energy radiation through the slot patterns drawn over the entire path, but partial areas such as e.g. in the gray areas, as long as the required screening thickness is maintained. The partial image b) accordingly shows an arrangement of metal sheets which enclose the slot profiles, wherein between sheets of adjacent slot profiles an absorbent material of high density is incorporated. The forming sheets themselves do not need to absorb as much as the material stored between them, so the shielding is ensured by the denser material stored between adjacent sheets.

FIG. 3 shows how the shapes of different slit curves in one

Multiple slit diaphragm to a common initial shape (mother shape) attributed can be. The partial image 3a) shows two superimposed slot profiles, which are aligned on a common central axis (dash-dotted line, transverse to the beam direction). These slot profiles can be covered at the top and bottom with a metal sheet, or directly adjacent to a metal sheet. The partial image 3b) shows the transfer of the lower slot profile (shown in darker colors) into a common plane with the upper one by a simple left shift. The slots surrounding walls of a sheet can thus be made for all slits of a common parent mold, for example by the sheets are punched with one and the same punch. Sheets for wrapping the slits in the individual layers can be cut from this "prototype", which is naturally wider than the individual slits, then cut by simply shortening.

Fig. 4 shows stepwise the transition from a fixed, or fixed multiple slit to the variable adjustable here proposed

Multiple slit. In this case, the partial image a) shows a multi-slot diaphragm in the block, as previously described in EP 2333786 Bl. The partial image b) shows the interruption of a slit (upper partial image) approximately in its middle (lower partial image), wherein the

Beam path itself is unaffected. The partial image c) shows the division of the massive multi-slot block into two half-diaphragms. The partial image d) illustrates the reduction of the diaphragm mass. Further explanations in this regard are given in the description of FIGS. 5 and 6 given.

5 shows the two half-diaphragms from FIG. 4c in plan view with one of a plurality of possible slot progressions. In the left part of the diagram, the slot pattern of a closed aperture in the foreground of the image is drawn in black while its from

Aperture body hidden back part (in the background) is shown in gray. The closed state of the panel is illustrated by the fact that the gray dotted line running from top left to bottom right along the top of the slot in the left slot block and along the bottom of the corresponding slot in the right slot

Slot block runs. A direct beam passage through the aperture is therefore not possible, the aperture is closed. Each beam through the interior of the slot in one of the two designed as a slit blocks body is blocked by the other body part, or the corresponding second slot block. In the right part of the picture, the aperture is shown in the open position, open position, after the right slot block has been moved down by about one column width. The required shielding in the closed state of the diaphragm takes place only through the layer thickness of one of the two slot blocks. This aspect is followed in the following FIG. 6.

In particular, Fig. 6 shows two half panels in a simplified form, intended for Brackets in which steeper incident radiation can be absorbed by a corresponding frame of the bracket. The closed position is shown in the left partial image, the open position in the right partial image results after a corresponding downward movement of the right part of the body. The shielding layer of each

taken away parts of the half-panels can be moved into the holder, which takes over in any case in the areas outside the visor body and the shielding function.

Fig. 7 illustrates the use of different dense materials for more effective shielding in the closed part of the beam path of the proposed aperture. The closed (left) and open panel (right) illustrations of Fig. 5 are supplemented with the transmitted and absorbed beams and those portions which may advantageously be made of denser material (see Fig. 8, hatched areas along the slot openings ). When closed (left), the rays pass through the first slit block (first slit) and are absorbed in the second slit block. In addition, only the portion of the first slit block for radiation absorption is available, which is located in a linear direction in front of the slot in the second. These parts of the visor body are highlighted in gray. They can be made of denser material to compensate for the missing layer thicknesses. While the visor bodies may be made of copper or brass, as denser material e.g. Tungsten serve. The right part of the picture shows the aperture in (fully) opened position with the passing rays

(dot-dashed).

While in the preceding figures, the object to be imaged is typically arranged behind the diaphragm, Fig. 8 shows an arrangement of the diaphragm to the object, in which the object is in front of the diaphragm, the imaging plane is thus behind the diaphragm: So it is shown the ray trajectory through the trapezoidal slit diaphragm with "reverse" installation The aperture is here aligned with its narrow side towards the object, so that the rays cross in front of the aperture in a vertical axis.This arrangement brings targeted and benefits for multi-slit arrangements specially thought to

to compensate for existing disadvantages of a strictly parallel slot arrangement (cf the references cited in paragraphs [0003] and [0052]). In Fig. 8, only one slot of a plurality of slots arranged one above the other is shown. A diagrammatic representation of the plurality of slots arranged in the panel runs the risk of becoming confusing and thus incomprehensible, therefore the selection of only one slot shown here. However, this selection expressly does not disclose an embodiment with typically multiple superimposed slots. According to preferred embodiments, the slit diaphragm proposed herein comprises at least one, for example 3, typically 5 or more, for example 7, 8 or 9 slots. The original purpose of the trapezoidal slit shape was to increase the viewing angle (EP 2 333 786 B1, PCT WO 2011/069770 A1). Thus, a position of the image plane before the intersection of the leg extensions of

Trapezoidal shape. In the form now proposed another purpose is pursued. Since, in a multiple array of parallel slots, i. close arrangement of non-trapezoidal shaped wide slits, a superimposition of parallel images could determine (DE10 2008 025 109 AI, EP 2 124 231 A2), is now proposed to remedy this deficiency the trapezoidal shape in the arrangement shown here. The elongated legs of the trapezoidal basic shape meet on the side of the diaphragm facing the object and form a second "focal axis" perpendicular to the first one within the diaphragm, thus avoiding parallel rays impinging on the diaphragm body through adjacent slits As a result, the image quality is significantly improved because the disturbing superposition of parallel images is avoided.

In the upper part of the aperture in the top view (from above) can be seen. With a short dashed line the central axis, with a long dashed line the outermost lateral beam path is shown. With a dotted line passing through the visor body, the resulting common axis of intersection of all the rays is shown, which pass through the aperture slot. Due to the trapezoidal shape of the visor body results in front of the diaphragm, a second cutting axis perpendicular thereto, which is shown here as a bold point, and which is perpendicular to the image plane.

The dotted line through this point forms the connection to the lower partial image, which shows a perspective side view of the visor body. It applies the same axis marking as before, the vanishing point is indicated by the wafer-thin dashed rays. For reasons of simplification, only the lower part of the visor body is shown in the lower partial image. The outermost lateral rays run at the edges of this body and intersect the dash-dotted sectional axis in front of the aperture in the manner shown in the upper partial image (in the plan view). Then they run apart again. Thus, two cutting axes are present in the beam path (dash-dotted lines

executed lines), one in the slot of the aperture and another perpendicular to it in front.

An advantage of these embodiments is that due to the quasi-parallel slots resulting and superimposed multiple images are avoided. However, for a mapping of the object, the distance of the object to the aperture must be

(Object distance) be significantly larger than the distance of the vertical axis of intersection to the aperture. For example, according to preferred embodiments, the object distance is at least 1.5 times, preferably twice or a multiple of the distance vertical cutting axis to the object-oriented side of the slit block (aperture).

According to preferred embodiments, the adjustment of the diaphragm is effected by means of a mechanical propulsion, for example by means of an electrically driven drive. Fig. 9 shows a side view of a mechanical propulsion for

Slot width adjustment of a multi-slot shutter. Here is a simplified form of partial apertures shown, as shown in Fig. 6. However, more slots can be placed up and down.

Fig. 10 shows a top view of a possible mounting of a multi-slot shutter in a housing, which can be easily installed in a conventional shield ("Bleiburg") consisting of individual lead seals, so-called "dovetails "is composed. An opposite movement of the partial apertures can be achieved, for example, by opposing screw threads in the driving rods.

Finally, Fig. 11 shows a bottom view of the drive of

Slot adjustment with adjusting wheels, the axes of the driving rod and their connection via a drive chain.

Here, as in all Figs. 9 to 11, reference numerals denote the following components:

1 front partial panel in the direction of the dial for

Slit width adjustment;

2 rear partial panel;

3 cover brackets with internal threads for setting advance, with opposite threads for the respective partial panels;

4 axes of drive rods for adjustment;

5 gears on the axes of the rods for Einstellvortrieb;

6 connecting chain between all axes for adjustment;

7 large gear on the left front axle for the Einstellvortriebsstange as a connection to the setting wheel; 8 thumb wheel;

9 holder for the setting wheel;

10 front shield above the adjustment mechanism, overlapping with the

actual aperture;

11 Connecting screws between cover and bracket, across to

Beam direction (to avoid leaks);

12 inclined end faces between the visor body and brackets to prevent passage of radiation (leak prevention);

13 part of the cover housing, here for installation in an experimental

Overall housing designed for a camera with lead seals.

In Fig. 12 - a design of the imaging device is shown with reduced mass - the example of only one slot. The thickness (material thickness) of the two slit blocks is reduced (see arrows in the left part of the picture), resulting in a mass reduction of the entire device. A suitable combination of materials comprises two different materials. One for a slit (thick) sheet immediately adjacent the slit along the beam direction is a more absorbent first material which performs the function of a "barrier." This barrier is hatched in Fig. 7. The remaining and majority of the slit blocks are of one It forms the major part of the slit diaphragm "diaphragm body" and bounds the slit on one side, on the side opposite the barrier layer of the more absorbent material. The barrier layer may comprise tungsten, for example, while copper, brass or bronze are selected as the diaphragm body. In the figure, a dashed line indicates the original full-thickness slit, while the reduction in wall thickness is indicated by thick solid lines. The arrows in the plane (left half of the picture) indicate the reduction in the wall thickness, the vertical arrows (right half) illustrate that the slot in the illustration is pulled apart for better visualization, but much closer in the operating state.

A design of the imaging device has already been described above, which is adapted for high-energy radiation in the range up to 300 keV: Compared to an imaging device adapted for a range of high-energy radiation by 1 MeV (1 MeV + 50 keV) is only 1/5 of the shielding thickness required. In case of Tungsten as the shielding material corresponds to a reduction of the wall thickness of the first and second slit blocks from 5 cm to 1 cm. This will be independent of

Shielding material achieved a weight reduction of about 80%, e.g. on 30 kg of 150 kg. Compared to an alternatively possible scale reduction of the aperture, in this case the width of the slit diaphragm (220) is maintained (compare FIG. 12). It is reduced only the wall thickness, the overall geometry of the thick-walled construction is maintained in principle. With the lighter design, it is possible, an imaging device comprising the described slit diaphragm and a detector, wearable and thus able to perform mobile. With a suitable support frame, the corresponding device, for example, carried by an operator on the

Be aligned and operated, so that a high-resolution image is also available under complicated measurement conditions, such as space cramped

Relationships with a fixed object.

With the known slit aperture camera (DE 10 2005 029 674 B4), objects successfully reproduced with Compton backscatter were successfully irradiated with an X-ray tube (last presented at the ICNDT 2012: N. Wrobel, K. Osterloh, M. Jechow, U. Ewert: X-ray backscattering: Variable Irradiation geometry facilitates new insights (see http://www.ndt.net/article/wcndt2012/papers/282_

wcndtfinal00282.pdf). Due to the independence of the operation of the

Slit aperture camera from the Einstrahlgeometrie get with the X-ray source

Images that were previously not possible with conventional X-ray backscattering. The backscatter behavior of individual material layers in the object could be controlled by targeted irradiation. Thus, it was possible to represent radiation-passive components as a silhouette against a bright background.

In the practical handling of this slit, there was the following problem in the experimental setup: The slit width was variable and could per

Micrometer be adjusted. However, it quickly became apparent that when the aperture was large, the images became noticeably blurred, but too little aperture causes too little radiation to reach the detector in order to obtain a recognizable image. The already issued EP 2333786 B1, which describes a diaphragm with multiple slots for enlarging the imaged area and for increasing the radiation incident on the image detector, does not provide adjustability of the slot widths. A mechanical one

Propulsion device for each slot would be disproportionately expensive, since all slots would have to be adjusted synchronously.

Against this background, starting from the knowledge that the

Slit diaphragm is not necessarily designed mirror-symmetrically in the beam direction must have proposed the multi-slot shutter described here. It suffices that each imaging beam is wrapped somewhere on its way to the image detector as if it were passing through a collimator. In other words, the diaphragm body with its radiation-selecting property can, in principle, be located at any point in the beam path. Thus, the central axis, through which all the slit planes pass, does not have to

inevitably located within the visor body, but may also be arranged in front of or behind it. A changed beam passage at this point affects all slots in the aperture.

Thus, it is proposed to provide only a mechanical slot width adjustment. The entire panel consists of a front and a rear partial panel (also referred to here as slot block), one of which is designed to be movable and the other permanently installed. This advantageously eliminates the need for an adjustment mechanism that acts on each slot. Details on this are explained with reference to the attached figures, in particular the derivation of the proposed slotted diaphragm from the previously known slotted diaphragm in FIG. 3, the functional principle of the new diaphragm in FIGS. 4 to 7 and an adapted drive mechanism in Figs. 8 to 10.

Although it can not be avoided that in the closed part of the

Beam path, the shielding only by a partial panel, or only by a slit block, but the thickness and / or the material of at least a portion of a wall of the slots enclosing sheets is chosen so that its Ab shield effect is sufficient for the intended application. In particular, it is shown in FIG. 6 that this circumstance, which at first appears disadvantageous, can be successfully compensated by the use of a denser material. For example, according to preferred embodiments, a slit block comprises tungsten, while the remaining parts of the shield bodies comprise or consist of copper or brass.

The proposed solution is based on the fact that the slit diaphragm does not necessarily have to be designed mirror-symmetrically in the beam direction. It suffices that each imaging beam is wrapped somewhere on its way to the image detector as if it were passing through a collimator. In other words, the diaphragm body with its radiation-selecting property can, in principle, be located at any point in the beam path. Thus, the central axis, through which all slot planes pass, need not necessarily be inside the visor body, but in front of or behind it. A changed beam passage at this point affects all slots in the aperture. So here only a mechanical slot width adjustment needs to be provided. The entire panel then consists of a front and a rear partial panel, one of which is movable and the other firmly installed. A mechanics on every single slot works, is unnecessary.

In summary, there are achieved advantages of the proposed

Embodiments in a lightweight construction of an aperture for X-radiation <400 keV; forming slit diaphragms from sheets rather than solid material milling; facilitating the production of numerous slots in a multi-slot shutter; the division of a whole body into assembled components; improved beam efficiency through the presence of multiple slots; the use of moldable materials for shaping the slots; pouring absorbent material between preformed slots; the possibility of producing all slots starting from a (larger) initial shape and thus facilitating mass production of the portable

Multiple slit.

Further advantages relate to or are based on the division of a solid diaphragm into partial diaphragm bodies or mutually displaceably arranged slotted blocks; the simple adjustability of multiple slots by displacement of the partial shutter body (slit blocks) against each other; the possibility of facilitating adaptation to an existing radiation intensity; a sharper image with sufficient radiation intensity; the provision of an adapted adjustment mechanism; a weight reduction

Adaptation of the design of the multi-slot shutter to lower beam energies

(Roentgen); the use of different dense materials; to each other

self-similar design of the slot walls in the overlap area; the further opening, which allows shorter exposure times for an unchanged high image quality;

The embodiments described above are advantageously suitable

1. high-energy radiation backscattered by both actively radiating (gamma ray emitting) bodies and unknown objects of investigation

Generating an image that is not detectable by a simple pinhole,

2. the imaging surface used for imaging by using

To increase multiple slits and through the use of sheets to

Gap limitation with subsequent filling of the intermediate spaces to be able to form slit profiles that preclude overlaying / multiple exposure (see FIGS. 2, 3);

3. to ensure the adjustability of the slot width by division into partial blocks (see Figures 4 to 6), wherein the slot wall, which is displaceable in the beam path, is reinforced with a denser material (see Fig. 7); 4. to provide a mechanical actuator coupled with a suitable drive to ensure reliable adjustment of a desired slot width (see Figures 9 and 10);

5. by selecting suitably tilted multiple slots and a trapezoidal shape of the beam course through the visor body, parallel passages or

To avoid multiple exposure when using the multi-slit reliably, and thus to achieve a high imaging quality.

Thus, on the one hand, a rational lightweight construction of a

Multi-slit aperture for use in Compton backscatter radiography provided and on the other hand, an adjustable version of a multiple slit for

Exposure adjustment provided in a camera for high-energy beam imaging.

In summary, a slit diaphragm is proposed, in particular for an imaging device which is suitable for limiting high-energy radiation emanating from a radiation source, in particular X-ray and / or synchrotron radiation. Furthermore, a manufacturing method for this multi-slot shutter and its use for imaging of a specimen of unknown material composition is proposed. The slit comprises: a first slit block and a second slit block, wherein the first and the second slit blocks a

Radiation absorbing part and at least one radiation-transmissive slot comprises. The first and the second slit block are mutually arranged so that in a first position of arranged in the first slit block at least one slot in exactly one arranged in the second slit block corresponding slot continues so that a passing through the first slot of the first slit block beam unhindered by the second slot block occurs - in other words: the aperture is open. In a second position of the two blocks to each other, the at least one slot of the first

Slit blocks on a slit-free area of the second slit block so that a beam passing through the first slit of the first slit block strikes a portion of the second slit block adjacent to the corresponding slit and thus can not penetrate the second slit block - in other words the slit is closed , Between an open and a closed position of the diaphragm, the two slit blocks can be precisely moved back and forth, so that a weakening of a radiation used for imaging is infinitely variable.

The present invention has been explained with reference to exemplary embodiments. These embodiments should by no means be construed as limiting the present invention Be understood invention. The following claims are a first, non-binding attempt to broadly define the invention.

Claims

claims

A slit diaphragm (220) for an imaging device (700) which is suitable for limiting high-energy radiation (400) emanating from a radiation source (100), in particular X-ray, gamma and / or synchrotron radiation, comprising: a first slit block and a second slot block, wherein the first and second slot blocks comprise a radiation absorbing portion and at least one radiation transmissive slot and the first and second slot blocks are mutually arrangeable such that in a first position the at least one slot located in the first slot block occupies exactly one continues in the second slot block corresponding slot so that a passing through the first slot of the first slot block beam passes through the second slot block unhindered, and in a second position, the slot of the first slot block on a slot-free area of the second slot block, thusThe beam passing through the first slot of the first slot block strikes a portion of the second slot block adjacent to the corresponding slot and thus does not penetrate the second slot block.

2. slit diaphragm according to claim 1, wherein the second position of a

Parallel displacement of the slots of the first slot block to those of the second slot block corresponds.

3. Slit diaphragm according to one of claims 1 or 2, wherein an adjacent

Surface region between the first and an adjacent second slot of the second slot block has at least one shape resulting from a projection of the cross-sectional area of the first slot of the first slot block on the first slot block facing surface of the second slot block.

4. Slit diaphragm according to one of claims 1 to 3, wherein a slot has at least two mutually opposite walls of at least partially identical shape.

5. slit diaphragm according to claim 4, wherein at least one wall comprises a metal sheet.

The slit of claim 5, wherein the sheet is selected from: aluminum, bronze, iron, copper, brass, nickel, steel, titanium, tungsten or an alloy comprising at least one of: Al, Be, Pb, Cu, Cr , Fe, Ni, Sn, Ti, W, Zn.

The slit of any one of claims 1 to 6, wherein the radiation-absorbing member comprises lead disposed between the walls of adjacent slits.

A slit diaphragm according to claim 6, wherein a first wall comprises a first sheet having a higher absorptivity for the high energy radiation than a sheet comprised by a second wall.

9. slit panel according to claim 8, wherein a thickness and / or a profile of the first sheet of the slot in the first slot block has at least one thickness and / or a profile of the corresponding slot in the second slot block, and a thickness and / or a profile of the second sheet of the slot in the second slot block has at least one thickness and / or a profile of the corresponding slot in the first slot block.

10. Slit diaphragm according to the preceding claims, wherein at least two of

Slots one and the same slit block have an identical cross-sectional area and / or shape.

A slit according to the preceding claims, wherein planes defined by the slits in the first slit block intersect each other in a line lying outside the first slit block on a side facing the second slit block.

12. slit diaphragm according to one of the preceding claims, wherein the X-ray,

Gamma and / or synchrotron radiation by means of an adjustable slit width of the at least one radiation-transmissive slot is adaptable so that a suitable for generating an image proportion of high-energy radiation through the slit diaphragm falls.

13. A slit according to any one of the preceding claims, wherein the high energy radiation is in the range from 50 keV to 20 MeV, for example in the range 150 keV to 1000 keV, typically in the range 100 keV to 450 keV.

14 slit diaphragm according to one of the preceding claims, wherein a shielding thickness of the slit diaphragm is adapted to a Engergiebereich high-energy radiation to 300 keV.

15. Slit diaphragm according to one of claims 12 to 14, wherein the slit width

between 1mm and 7mm is adjustable.

A manufacturing method for a high-energy radiation slit (220) as described in claims 1 to 15, comprising:

Forming at least two sheets on an output molding;

Equidistantly connecting two sheets each to each other so that the interconnected sheets form a channel, the channel having a first open end and a second open end opposite thereto; Arranging and aligning the channel in a mold;

Filling the mold with a lead-containing melt such that the channel is not filled with the melt;

Removal of a cast body obtained in the casting mold comprising the channel.

The manufacturing method according to claim 16, further comprising: dressing the cast body into a slit block.

The manufacturing method according to claim 17, further comprising:

Adjusting and aligning a first and a second slit block so that, in a first position, the at least one slit disposed in the first slit block continues in exactly one corresponding slit in the second slit block such that a beam passing through the first slit of the first slit block passes unhindered through the second slot block passes, and in a second position the slot of the first slot block faces a slot-free area of the second slot block so that a beam passing through the first slot of the first slot block meets a portion of the second slot block adjacent to the corresponding slot and so on does not penetrate the second slot block.

19. The manufacturing method according to claim 18, further comprising:

Providing a drive for a gradual change between the first and second positions such that a resulting thickness of a beam passing the first and second slit blocks is adjustable as needed.

20. The manufacturing method according to claim 19, further comprising:

Arranging an image pickup unit on one side of a slit block such that a beam falling through the slit hits a detecting area of the image pickup unit.

21. Use of a slit diaphragm (220) described according to claims 1 to 15 for the imaging of a test specimen by means of exposure to high-energy radiation, wherein a radiation source of high energy

Radiation, a test specimen and the slit diaphragm are arranged so that the test specimen backscattered shares of high-energy radiation through the

Slit diaphragm on an image pickup unit and / or on a detector meet.

22. An image generation method for non-destructive material testing of an object (300) with high-energy radiation, in particular with X-ray, gamma and / or synchrotron radiation, comprising:

Providing an imaging device (700) comprising a slit (220) according to at least one of claims 1 to 15 and a detector (600);

Arranging the imaging device and the object such that high-energy radiation emanating from the object and / or backscattered hits the detector of the imaging device through the slit diaphragm;

Setting a slit width of the slit diaphragm of the imaging device with respect to a radiation intensity, so that at the set slit width, a suitable for generating an image portion of the emanating from the object and / or backscattered high-energy radiation is passed to the detector.

The image forming method of claim 22, wherein the object comprises a composite material and the non-destructive material testing permits detection of inclusion and / or inhomogeneity in the composite material. An imaging device (700), comprising a slit (220) having at least one radiation-transmissive slit and a detector (600), wherein a high-energy radiation (400), in particular X-ray, gamma and / or

Synchrotron radiation, with respect to a radiation intensity by means of an adjustable slit width of the at least one radiation-transparent slit is adaptable so that emanating from an active radiating object and / or backscattered by an unknown object high-energy radiation at the set slit width suitable for generating an image proportion of high-energy radiation ( 400) passes through the slit on the detector, the slit comprises a first slit block and a second slit block, each comprising a radiation-absorbing part and at least one radiation-transmissive slot and the first and the second slit block are mutually arranged so that in a first Position of the arranged in the first slot block at least one slot in exactly one arranged in the second slot block corresponding slot continues so that a through the first slot of the first slot block s extending beam passes unhindered through the second slot block, and in a second position, the slot of the first slot block on a slot-free area of the second slot block, so that a passing through the first slot of the first slot block beam to a region adjacent to the corresponding slot of the second slot block and the beam thus does not penetrate the second slot block.

25. Imaging device according to claim 24, wherein the radiation-permeable slot has at least two mutually opposite walls of at least

having sections of identical shape.