FI64721B - ADJUSTMENT FOER ATT PROEVA FOEREMAOL MEDELST STRAOLNING - Google Patents

Description

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National Board of Patents and Registration of NShuvSkaipanon And heard Date of publication— Ί] _ t q8.83

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Sweden-Sweden (SE) 7ö06l34-0 (71) Tekniska Röntgencentralen AB, Björnnäsvägen 21, 3-104 05 Stockholm 50, Ruo ts i-Sve ri ge (SE) (72) Gösta Nyström, Täby, Sweden-Sverige (SE) (7 ^) Oy Heinänen Ab (5M Search device for examining objects, with radiation -

Avsökningsanordning för att pröva föremäl medelst straining

The invention relates to a search device for examining objects by radiation or X-rays of radioactive substances, comprising a body of anti-radiation material in the form of a rotatably mounted and connected to the drive device, having a chamber between the body and a radiation detector radiation-transmitting narrow channels.

Such search devices are known, for example, from DE-AS 10 95 955, DE-AS 10 90 784, US-PS 2 825 817 and US-PS 2 477 307. Such devices are used in medicine, security or industry. Those 2 6 4 7 21 are point finders that affect the mechanical deflection of test rains. From US-PS Re. 28 544, a device with a search device for obtaining a narrow beam guided at right angles to a rotating plate provided with elongate apertures extending radially from the circumference of the plate, Xoska, it is difficult to generate well-defined moving rays and thus allow well-defined points to pass along the subject. object, the resulting image becomes confusing. The use of such devices has therefore so far been limited to simple investigations, such as the examination of suitcases at airports.

An essential common feature of all said devices is that they have a rotating bearing block or disk as the main part. These drums or discs are provided with bores or slits through which the rays of the radiation source are directed to the object to be examined. They are relatively thin in the direction of travel through the rays.

The ranges of use of such devices are limited in terms of radiant energy. If you want to study objects, such as steel structures, that cause a relatively large amount of radiation. deterioration, must move to higher energy rays. As the power increases, the wall thickness of said drums or discs should be increased accordingly, because otherwise the radiation would penetrate not only through the channels but also through the rest of the drum jacket. But this measure again imposes limitations. Thus, although DE-AS 11 30 089 discloses a device with a high wall thickness rotating guard with a detector arranged in the chamber, in this case the channel is so wide that an accurate point search is not possible.

The object of the invention is therefore to provide a device such as that mentioned at the beginning, so that it also generates a search for a well-defined beam 7 a r t o n with a high energy of radiation.

3,64721 This object is solved in a search device according to the invention as mentioned at the outset, as defined in the characterizing part of claim 1.

An advantage of the invention is that the grooves are made by fine workmanship and can be dimensioned as desired to obtain the best possible radiation geometry. This is not possible if the channels consist of thighs drilled into a massive body.

Embodiments of the invention will be described in connection with the accompanying drawings.

Fig. 1 shows schematically; perspective and simplified search engine,

Fig. 2 schematically shows details of the device shown in Fig. 1,

Fig. 3 shows a plate-like body in the device according to Fig. 1 in axial section,

Fig. 4 shows the second half of the body shown in Fig. 3,

Fig. 5 schematically shows another embodiment of the invention.

Figures 1 and 2 show a plate 1 attached to a shaft 2, which in turn is driven by a motor 18. The plate 1 has radial channels. An X-ray source or a radioactive substance is arranged as a radiation source at the center of the plate so that the well-defined beams are successively directed at the object 3 to be examined. The beam 4 is marked in Fig. 1 by a broken line. The object 3 is moved on the conveyor belt 5 substantially parallel to the axis 2 and the object thus moves past the plate 1. Each radius 4 emanating from the plate 1 senses the object 3 along the path 4 ', as can be seen from Figure 1 64721. Target 3 is normally transmissive. Said beam thus penetrates. The beam exiting the object 3 meets a detector 6 which is elongated in shape and which is arranged in a plane defined by the movement of the beam. The beam is partially absorbed as it passes through the object 3. If, for example, a beam encounters a stone or other object in a branch of a metal object * whose density differs from the normal density of the object or object 3, a significant change in absorption occurs. The electrical signals generated by the detector 6 depend on the transmitted irradiated material and the intensity and energy of the radiation encountered. As the beam moves from the upper end of the detector to its lower end, the direction of rotation being assumed here, a number of pulses depending on the intensity of radiation are generated in the detector 6. The detector 6 is, for example, a scintillation spectrometer. The signals from the detector 6 can be fed, for example, to an analyzer, calculator or other desired device 7. The detector 6 can of course also be replaced by several detector parts arranged sequentially in the same plane as the sweep plane or in a plane parallel to the sweep plane. In the latter case, different parts of the wider scanning beam or several scanning beams obtained by arranging different channels on the plate 1 for each scanning beam meet different parts of the detector.

In order to obtain very limited narrow beam beams, the plate 1 is formed as shown in more detail in Figures 2-4.

Figure 2 shows a plate 1, the shaft 2 of which is mounted on two bearing members 8 and 9, respectively. These bearing members 8,9 are fastened to the wall 12 of a housing 12 indicated by dotted lines 13 with bolts, for example 10 and 11, in this housing made of lead or other of a suitable material to prevent the uncontrolled entry of radiation into the environment, there is an opening 14 in the wall 12 and the radiation from the circumference of the plate 1 exits through this opening 14 towards the detector 6. A pulley 15 is arranged on the shaft 2 of the plate 1, and via the belt 16 a radiating plate is driven by a second pulley 17 attached to the shaft of an electric motor 18 or other power source. The plate 1 has internal channels extending from the circumference of the plate to the center of the plate in a space arranged for the radiation source 20, i.e. in the chamber 19 (Fig. 3). Fig. 3 shows two such channels 21 and 22. As further shown in Fig. 3, the plate 1 is formed of two plate halves 23 and 24. Fig. 4 shows the plate half 24 and more specifically its flat inner surface. Grooves 25-40 are made in this surface, leading to the circumference 41 of the plate and to the center of the plate half, respectively, with a recess 42 forming part of the space 19 for the radiation source 20. This radiation source must be placed in line with the direct channels, for example the channels 21 and 22 shown, which channels are then formed by making grooves in the flat inner surface of the plate half 23 of the toi-St, and . The plate halves made of an anti-radiation agent, for example steel, are firmly fastened to each other by bolts, for example by bolts 43 (Fig. 3). Figure 4 shows holes, for example holes 44 and 45 for bolts.

Although, for manufacturing reasons, it is most convenient to make grooves in only one plate half, it is of course possible to arrange corresponding grooves in pairs in each plate half in pairs.

In order to obtain a high sensitivity, it is essential that the radiation attenuation between the channels is good, i.e. that there is as little background noise as possible and that when two plate halves are used, the fit between their opposite surfaces must be good to avoid inter-channel radiation leakage.

6,64721

It has been assumed above that the grooves are of uniform width, but preferably each groove expands from the radiation source towards the circumference of the plate. Regardless of the shape of the grooves, outward radiation in the form of narrow beams is obtained, the geometry of which is constant in all directions and independent of the energy of the radiation.

Shaft 2 is assumed above to be a drive shaft and thus rotatable together with the body 1, but it is also possible to use a stationary shaft on which the body rotates. An essential advantage of the shown hollow shaft is that the radioactive preparation can be stored in a fixed, stationary position supported by a holder that passes through the shaft.

It has been assumed above that the object move and the detector and the radiation device are fixed, but of course the detector and the control devices can also be moved past the stationary object.

Figure 5 schematically shows an apparatus for examining radiation emitted from an object 3, indicated by arrows R. An object 3 ", which may be, for example, a patient in a hospital with a radioactive preparation, a radioactive machine part, a container or an article containing a radioactive substance," which is irradiated from the back side is assumed as the conveyor in Figure 1 (not shown) and transferred in the direction of arrow A direction. the article can be simultaneously rotated about an axis or simply to rotate it to transfer. the device of the type described above is set in the radiation path, and the disc 1 'center space 19' includes a detector (not shown). When the disc 1 'rotates and the object 3 "moves to the direction of arrow A direction shall plate 1' through a corresponding channel in a very limited beam as received, and this beam is varied along its position scan lines, which are more or less densely covered with the object 3 '. The detector in state 19 'will thus at all times generate an output signal which is the value of the radiation intensity 64721 7 at the point of the object which the channel is currently "watching". This signal is sent along line 46 to the pointing device 7 ".

Claims (3)

64721 8 A search device for examining objects by radiation or X-rays of radioactive substances, comprising a body (1) of rotating bearing and enclosed in a circular manner, connected to the actuator, having a radiation barrier centered by a chamber for a radiation source (2) or a radiation detector radiation-permeable narrow channels (e.g. 21, 22) pass between the outer surface and the chamber, characterized in that the body (1) is assembled from two closely spaced circular plate-shaped halves (23, 24) at their end faces and that the channels (e.g. 21, 22) 22) is formed by grooves (25-40) formed in at least one of the opposing end surfaces. A search device according to claim 1, characterized in that both halves (23, 24) are mounted on a hollow shaft (2) and that said chamber (19). is accessible via a hollow axis. A search device according to claim 1, characterized in that on each channel (21, 22, 25-40). is a substantially rectangular cross section. 11