DE3035524A1 - SCREEN RAY SCREENING ARRANGEMENT - Google Patents

Description

PHILIPS PATENTVERWALTUMG GMBH 9 PHD 80-129

"Anti-scatter fluoroscopy arrangement"

The invention relates to an arrangement for determining the internal structure of a body, with at least one Radiation source for emitting a primary beam penetrating the body, which in at least one Area has an almost punctiform cross-section; and with at least one detector-collimator arrangement, only the radiation emanating from the punctiform cross-sectional area and scattered over a solid angle area detects the one different from the primary beam direction Direction owns "

Such an arrangement is already known from DE-OS 2k 6l 877. The collimator is focused on a thin primary beam that penetrates the body, while the detector located behind the collimator measures the intensity of the total scattered radiation passing through the collimator in order to determine a single value that can be assigned to the point on the body, for example the body density this point corresponds to <■ The detector delivers a detector output signal for each point on the body under consideration.

To represent a larger area of the body, several adjacent body points are considered and for these corresponding density values are determined with the aid of the scattered radiation measured in each case. To be .both <iio detoctor-collimator arrangement as well as the Primary beam shifted relative to the body. 3 "are therefore only ever considered body points that are from the primary

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PUD 80-129

ray can be irradiated .. The arrangement is not suitable for determining the internal structure of Body areas that are not penetrated by the primary chest.

The object of the invention is to provide an anti-scatter examination arrangement specify, with which the internal structure of body areas can be determined that lie outside the primary beam.

10

This object is achieved according to the invention in that / - The detector arrangement is designed such that with it in each case in different directions within the scattered radiation running in the solid angle range can be measured separately.

The detector arrangement is sufficiently high for this Spatial resolution, so that from point-to-point area from, which can practically be viewed as a virtual radiation source, the one between it and the collimator arrangement transilluminated lying body area and recorded a shadow image of this with the aid of the detector arrangement can be. The punctiform area can be created by shifting the radiation source and the collimator-detector arrangement in the vicinity of the body structures to be examined so that only a relatively small part of the body needs to be irradiated » This is advantageous because it can be achieved that in the majority of cases only those that are actually of interest Body structures lie in the beam path of the scattered radiation and the fluoroscopic image is not unnecessarily obscured by uninteresting body structures?

The arrangement is particularly suitable for material testing, e.g. for examining mater! al fail em (air intake

ORIGINAL INSPECTED

80-129

Circuits) in aluminum castings or the like ,, this purpose, the point-like area (or the virtual radiation source), for example, brought into the vicinity of a stressed to high mechanical stress-material location which is irradiated by the emitted by the point-shaped region stray radiation beam _o can be on the fluoroscopic image then It is relatively easy to see whether there are air pockets that are detrimental to the strength of the material or not »

The drawing shows exemplary embodiments of the invention.

Fig. 1 a scattered radiation fluoroscopy

arrangement with a thin X-ray

Primary beam,

Figure 2 is an anti-scatter fluoroscopy

arrangement with a focused gamma ray beam, and

Figure 3 is an anti-scatter fluoroscopy

arrangement with a combined gamma ray source detector arrangement.

The arrangement shown in FIG. 1 has an X-ray source 1, the X-ray radiation 2 of which is masked out by means of a diaphragm 3 to form an X-ray primary beam 4 with a thin cross-section, which penetrates a body 6 lying on a table 5, for example a workpiece to be tested . To display body structures 7 to be examined or to check whether there are any special body structures in a certain area of the body, for example air pockets in a casting, the body 6 and the X-ray source 1 are shifted to one another in such a way that the primary beam h. runs in the vicinity of the body structures 7 to be examined »

^PHD 80-129

To the side of the primary beam k is a detector-collimator arrangement 8, 9 j which detects the radiation extending from a point-shaped body area 10 located in the primary beam 4 and scattered in a solid angle area 11 outside the primary radiation. For this purpose, the detector arrangement has a high spatial resolution, such that the scattered radiation running in different directions or on different scattered radiation paths within the solid angle region 11 can be measured separately. The detector-collimator is 8.9 k to the primary beam arranged further relatively comparable r-, adjustable, so that in each case different regions of the body can be examined.

With the help of the detector-collimator arrangement 8, 9 thus generate shadow images of the body structures 7 to be examined without larger bodies in the process areas need to be irradiated. The point-like body area masked out by means of the collimator arrangement 9 10 can be viewed as a "virtual radiation source" will. To hide this area, the collimator arrangement 9 has, for example, lead lamellas lying in planes 9a, the planes intersecting in a line that traverses, e.g., perpendicular, to the direction of the primary beam the point-shaped body region 10 runs. The collimator assembly but can also consist of a two-dimensional anti-scatter grid that is based on the punctiform The area is focused and also serves to suppress multiple scattering.

30th

The detector arrangement 8 consists, for example, of an X-ray image intensifier containing opto-electronic image converter, with an electronic unit 12 for processing the detector output signals and is connected to a monitor 13 for displaying the shadow images. To you;

ORIGINAL JNSPECTED

Ζξ,

PHD 80-129

The detector arrangement 8 can be designed in such a way that it completely or partially surrounds the primary beam 4. Occurring differences in intensity of the scattered radiation due to the angular dependence of the scattering 12 can be corrected by appropriate processing of the detector output signals, of course, by means of f. Of the electronic unit.

The shadow images can also be shown on film or by means of another suitable detector Record jQ with spatially resolving properties, for example by means of a detector field (detector matrix) consisting of scintillators or semiconductor detectors.

The arrangement shown in FIG. 2 has a planar gamma ray source 14 as a radiation source, which is shown in FIG a radiation protection housing 15 is arranged. Before the

137 Gamma ray source 15, which e.g. consists of Cs (662 KeV), there is a collimator 16, which only lets through the gamma rays 17 exiting from the surface, which are directed to the point-shaped body region 10 ', i.e., the collimator 16 focuses the gamma rays on the point-shaped Body area 10 '"For creating shadow images the body structures 7 'to be examined are provided with a spatially resolving detector arrangement 8', which also like the gamma ray source 14 to change the position of the punctiform area 10 ′ can be displaced relative to the body 6 is arranged. Of course, the body 6 can also be moved in its position by corresponding movements of the table 5 relative to the radiation source detector arrangement.

The planes in which the collimator leaves 9'a lie, also intersect here in a line passing through the punctiform area 10 'and transversely to the primary beam direction, e.g. perpendicular to the line of symmetry of the primary beam, runs. Of course, the collimator arrangement 9 ′ can also be designed as a two-dimensional anti-scatter grid here focused on the punctiform area,

^{PHD 8} ° - ¹² 9

3 shows a combined radiation source-detector arrangement 14 ', 8, ¹¹ , with which radiation 19 scattered at very large angles to the primary radiation direction 18 can be measured (backward scattering).

The radiation source Ik 'consists of an annular disk arranged, radioactive material, such as Cs (662 keV), while the position-resolving detector array 8 in the center of the annular disc' is ^1. Below the entire radiation source detector arrangement there is a collimator arrangement 9 ″ whose lamellae 9 ″ a are cone-shaped and are arranged in such a way that only gamma radiation that penetrates a punctiform area 10 ″ coming to lie in the body 6 is allowed to pass through (18 ) or comes from this area 10 ″ (19) = the collimator arrangement 9 ″ is therefore focused on the area 10 ″. In this arrangement, due to the special beam geometry (very large angle between the primary and the scattered radiation direction) scattered radiation is detected from a relatively large part of the focus area of the primary radiation, so that this results in a high intensity of the virtual radiation source. This also applies to the arrangement according to FIG. 2 when the angle between the q -ray bundle 17 and the detector arrangement 8 'is very large or very small. The resolving power of the arrangement does not deteriorate in this case, since the extent of the focus area perpendicular to the beam direction is comparatively small. The area 10 ″ can also be viewed as an isotropic radiation source, since with such large scatter angles there is practically no angle dependency of the scattered radiation. By means of the scattered radiation (I9) emanating from the area 10 ″, the body structures 7 ″ to be examined can be imaged and with the aid of the detector arrangement 8 ^I! can be detected. The detector arrangement 8 ″ is adequately protected from radiation that comes directly from the radiation source Ik ′.

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Claims (3)

PHD 80-129 PATENT CLAIMS: flJ arrangement for determining the inner Structure of a body with at least one radiation source for emitting a primary beam penetrating the body, which is in at least one area (10) has an almost punctiform cross-section ^ and with at least one detector-collimator arrangement, which only includes the point-shaped cross-sectional area and detects radiation which is scattered over a solid angle range and which differs from the primary beam direction Has direction characterized in that the detector arrangement (8, 8 ', 8' ¹ ) is designed in such a way that it can be used to separately measure the scattered radiation running in different directions within the solid angle range. 2. Arrangement according to claim 1, characterized in that the radiation source is an X-ray source (l), the radiation of which is masked out to form a thin beam (k) , and that the focus of the collimator arrangement (9) lies on the beam. 3. Arrangement according to claim 1, characterized in that the radiation source is a planar radioactive radiation source (14), the radiation emerging from the surface is focused point-like by means of a collimator (l6). k. Arrangement according to claim 3i characterized ^ou characterized in that the areal radioactive source (lA ') has a central opening for receiving the detector arrangement (8 ^1').