FR2490480A1 - X-RAY DEVICE OPERATING USING DISPERSE RADIATION - Google Patents

Abstract

THE INVENTION CONCERNS A DEVICE SERVING TO DETERMINE THE INTERNAL STRUCTURE OF A BODY 6, INCLUDING AT LEAST ONE RADIATION SOURCE INTENDED 1 TO EMIT A PRIMARY RAY BEAM 4 THROUGH THE BODY WHICH HAS A PRACTICALLY PUNCTUAL SECTION 10 AT LEAST IN ONE REGION AND AT LEAST ONE 8-9A DETECTOR-COLLIMATOR DEVICE THAT DETECTS ONLY SCATTERED RADIATION THROUGH A SOLID ANGLE 11 DETERMINED. THE SENSOR DEVICE IS SHAPED IN SUCH A MANNER THAT THE DISPERSED RADIATION EXTENDING IN VARIOUS DIRECTIONS WITHIN THE SOLID ANGLE CAN BE MEASURED SEPARATELY.

Description

"Radioscopy device operating using scattered radiation." The

  The present invention relates to a device for determining the internal structure of a body, comprising at least one radiation source for the emission of a primary beam of rays passing through the body which has at least in a region a practically punctual section, and at least one detector-collimator device for the selective detection of radiation from the region of the point section which is dispersed in a solid angle and which is

  directed in a direction deviating from that of the primary radiation

  mayor. Such a device is described in the published German patent application OS 2 4 61 877. A collimator then forms a thin primary beam passing through the body while a detector placed behind the collimator measures the intensity

  of all the scattered radiation passing through the collima-

  tor to establish a distinct value associated with a corresponding point of the body and concerning the density of this body at this point. The detector therefore provides each time a signal of

  detector output for a planned point on the body.

  To represent a larger region of the body, we consider several points of the body arranged next to each other and, for these points, corresponding density values established by means of the scattered radiation which

  is measured each time. To this end, the detector device

  collimator and the primary beam are moved relative to the body. So we always only look at points

  of the body which are crossed by the primary beam. The dis-

  positive is therefore not suitable for determining the

  internal structure of regions of the body which are not

the primary beam.

  The object of the invention is to provide an examination device

  men radioscopique which, by means of a scattered radiation, also makes it possible to establish the internal structure of regions

  of the body lying outside the path of the rays of the

primary skin.

  This object is achieved, in accordance with the invention, by the fact that the detector device is designed to measure

  on the other hand scattered radiation extending in directions

  different positions within the solid angle.

  The detector device has for this purpose a power

  sufficiently high local resolution so that

  10 shot of a point region, which can be considered here as a source of virtual radiation, the region of the body lying between this region and the collimator device can be measured and a silhouette of this region of the body can be formed. The point region can then be brought by displacement of the radiation source and the collimator-detector device near a part of the body to be examined, so that it is sufficient each time to submit a part

  proportionally small of the body to the action of the rays.

  This is interesting because it is thus possible to have-

  lead that really important parts of the body for

  the examination in the path of the scattered radiation and that the ima-

  X-ray age is not disturbed by neighboring parts

nes of the body.

  The invention is also suitable for examining materials, for example for detecting defects such as air occlusions in, for example, cast aluminum parts. For this purpose, the point region (or the source of virtual radiation) is brought for example in the vicinity of a region to be subjected to high mechanical loads, this region then being traversed by the scattered radiation leaving the point region. On the x-ray image, we can then see quite easily if there are occlusions

  of air limiting the intensity are present or not.

  Embodiments of the invention are illustrated in the accompanying drawing in which - Figure 1 illustrates a radioscopy device operating with the aid of scattered radiation produced by a thin primary X-ray beam; FIG. 2 illustrates a radioscopy device operating by means of scattered radiation produced by a focused gamma ray beam, and

  - Figure 3 illustrates a radioscopy device operated

  rant by means of scattered radiation produced by a

  gamma ray source combined with a detector device.

  The device represented in FIG. 1 comprises a source 1 of X-rays, the X-rays 2 of which are diaphragmed by means of a diaphragm 3 into a primary X-ray beam 4 of thin section which passes through a body 6 placed on a table 5, for example a work to be examined. For the representation of the body structures 7 to be examined or for an examination aimed

  to determine if particular structures are effective-

  ment present in a specific region of the body, for example

  full of air occlusions in a poured structure, the body 6 and the source 1 of X-rays are moved relative to each other in such a way that their primary beam 4

  extends in the vicinity of the structures 7 of the body to be examined.

  Next to the primary beam 4 is a detector-collimator device 8, 9 which detects the radiation at

  outside the primary bundle, starting from a ponc-

  tuelle 10 of the body located in the path of the primary beam

  re 4 and dispersed in a solid corner region 11. The dispo-

  this detector has a high local resolving power for this purpose, so that the stray rays which extend

  in various directions or along various ray paths-

  parasite in region 11 of the solid angle can be measured separately. The detector-collimator device 8, 9 is further mounted movable relative to the primary beam 4 so that regions of the body each time

  different can be examined.

  The detector-collimator device 8, 9 therefore allows

  to obtain silhouettes of the structures 7 of the body to be examined

  ner without larger areas of the body to be crossed by the rays. The point region 10 of the diaphragm body by means of the collimator device 9 can then be considered as "virtual radiation source". To diaphragm this region, the collimator device 9 comprises for example lead strips 9a, arranged in planes, these planes intersecting along a line which passes through the point region 10 of the body, transversely, for example perpendicular to the direction of the radiation primary. The collimating device can however also be formed from a two-dimensional scattered radiation frame which is focused on the point region and which serves to

  better suppress multiple dispersion.

  The detector device 8 consists for example of an opto-electronic image converter comprising a

  x-ray image amplifier which is connected to a uni-

  electronic tee 12 for the preparation of the detector output signals and a monitor 13 for the representation of the radioscopic images. The detector device 8 can then be formed in such a way that it completely surrounds or

  partially the primary beam 4. The differences in

  intensity of stray radiation resulting from the influence

  angular on the dispersion can naturally be corrected

  managed by means of the electronic unit 12 by a processing

  corresponding detector output signals.

  Silhouettes can also be saved

  on a film or by means of another suitable detector presented

  both a local resolving power for example by means

  a detector field (detector matrix) formed of scintilla-

  semiconductor detectors or detectors.

  - The device shown in Figure 2 comprises, as a radiation source, a source of flat gamma rays 14 which is installed in a case 15 for protection against radiation. In front of the source of gamma rays 14, which is for example made up of 137Cs (662 keV) is a collimator 16 which lets pass only the gamma rays 17 coming from the plane and pointed at the point region 10 'of the body, this is - that is to say that the collimator 16 focuses the gamma rays on the point region 10 'of the body. To obtain silhouettes of the 7 'structures of the body to be examined,

  an 8 'detector device with resolving power is provided

  tion local which, like the source of gamma ray 14, is mounted movable relative to the body 6 to change the position of the point region 10 '. It goes without saying that the

  1O position of the body 6 can also be modified by displacements-

  corresponding elements of table 5 with respect to the radiation source-detector device assembly. The plans in

  which are arranged the collimator strips 9'a

  here also intersects along a line which passes through the point region 10 'and is transverse to the direction of the primary radiation, for example perpendicular to the axis of symmetry of the primary beam of rays. Naturally, the collimating device 9 ′ can also in this case

  have the form of a two-dimensional scattered radiation frame

  which is focused on the point region. A radiation source-detector device 14 ', 8 "assembly

  is shown in Figure 3 and allows to measure the radius-

  dispersed 19 (retrodispersion) under very large

  angles with respect to the direction 18 of the primary radiation.

  The radiation source 14 ′ is made of a radioactive material in the form of a disc, for example 137Cs (662 keV)

  while in the center of the annular disc is the device

  detector with 8 "local resolution power.

  the collimator 9 "is provided below the whole of the radiation source-detector device assembly and its lamellae 9" a are conical and are nested one inside the other so as to allow only the gamma radiation passing through ( 18) a 10 "point region coming from

  place in the body 6 or which leaves (19) from this region 10 ".

  The collimator device 9 "is therefore focused on the region". Based on a particular geometry of the radiation

  (a very large angle between the directions of the primary radiation

  mayor and scattered radiation) this device detects scattered radiation in a relatively large part of the focal region of primary radiation, which gives a high intensity of the source of viral radiation.

  tuelle. It is the same also for the device represented

  tee in figure 2 when the angle between the beam of ra-

  yons gamma 17 and the detector device 8 'is very large or very small. The resolving power of the device

  is not altered because the extension of the focal region

  The reading perpendicular to the direction of the radiation is comparatively low. The 10 "region can also be considered as a source of isotropic radiation because, for such large dispersion angles, there is practically no more angular dependence on the scattered radiation. The 7" structures of the body to be examined can be visualized by means of stray radiation (19) from

  the 10 "region and can be detected using the device

  8 "detector. The 8" detector is then sufficient

  strongly protected against direct radiation

  14I radiation source.

Claims (4)

  1.- Device for determining the internal structure of a body, comprising at least one radiation source for the emission of a primary beam of rays passing through the body which has at least in one region, one section   practically punctual (10), and at least one device   collector-collimator for the selective detection of the   starting from the point section region which is dis-   persed in a solid angle and which is directed in a direction deviating from that of the primary radiation, characterized in that the detector device (8, 8 ', 8 ") is designed to measure separately a scattered radiation extending in   different directions inside the solid angle.   2.- Device according to claim 1, characterized in that the radiation source is a source (1) of   X-rays comprising a collimating device (9) diaphragm   mant the radiation to a thin beam of rays (4),   a focal point of the collimator device is found   on the path of the primary beam.   3.- Device according to claim 1, characterized   in that the radiation source is a ray source-   flat radioactive element (14) of which the radiation leaving the plane is focused in a punctual manner by means of a collimator (16).   4.- Device according to claim 3, characterized in that the flat radioactive radiation source - (14 ') has a central opening intended to receive the detector device (8 ").