Patent Number: 
Section: claims

1. Dental radiology apparatus comprising:a generator (18) provided with a window (18b) emitting X-radiation and a collimation device positioned in front of said window in order to collimate the radiation in a suitable manner using several forms of collimation slits,at least one sensor (20a, 20b) comprising a first image acquisition surface elongated along a Z-axis perpendicular to a plane P and being used in a first position of the apparatus to produce a panoramic image of a jaw placed between the generator and the first image acquisition surface, the panoramic image being produced from the X-radiation collimated by a first form of collimation slit (22a) elongated along the Z-axis and received by the first sensor image acquisition surface and by displacement of the generator and of said first surface along a given trajectory in the plane P combined with a rotation about an axis parallel to the Z-axis, the said at least one sensor comprising a second image acquisition surface used in cone beam tomographic mode, in a second position of the apparatus, to produce a three-dimensional model of only a part of the jaw from the X-radiation collimated by a second form of collimation slit (22b) and received by the second image acquisition surface and by displacement of the generator and of said second surface in rotation about an axis parallel to the Z-axis, the second form of collimation slit having dimensions matched to those of the second image acquisition surface, characterized in that the apparatus is able to occupy a third position of use and to this end comprises means of positioning, in front of the window emitting X-radiation, a third form of collimation slit (22c) elongated in a direction parallel to the plane P and arranged opposite a third image acquisition surface corresponding to a part of the second surface along the Z-axis in order to cooperate with the third image acquisition surface, the longitudinal dimension of the slit in the direction parallel to the plane P being matched to the dimension of the second image acquisition surface in this same direction. 2. Apparatus according to claim 1, characterized in that it comprises means of obtaining in cone beam tomographic mode a predetermined number of three-dimensional models each representing a different part of the jaw from an assembly comprising third image acquisition surface and generator provided with the third form of collimation slit elongated parallel to the plane P. 3. Apparatus according to claim 2, characterized in that each first, second and third image acquisition surface of the said at least one sensor is an array of pixels or a sub array of pixels, and the predetermined number of three-dimensional models depends in particular on the size of the array or the sub array of pixels of the third image acquisition surface. 4. Apparatus according to claim 1, characterized in that it comprises:means of positioning, in the plane P, about a fixed axis parallel to the Z-axis, the assembly comprising third image acquisition surface and generator provided with the third form of collimation slit elongated parallel to the plane P;means of driving in rotation, about the fixed axis of rotation, the assembly comprising third surface and generator;means of acquiring several image signals of a part of a jaw illuminated by the radiation collimated by the third form of slit oriented parallel to the plane P for a plurality of angular positions occupied by the assembly comprising third surface and generator during the rotation movement. 5. Apparatus according to claim 4, characterized in that the positioning means are able to position the assembly comprising third image acquisition surface and generator provided with the third form of collimation slit elongated parallel to the plane P successively about other fixed axes of rotation in order that, for each positioning about one of these other axes of rotation, the drive means and the acquisition means are able to cooperate with a view to acquiring image signals of another illuminated part of the jaw. 6. Apparatus according to claim 4, characterized in that it comprises means of obtaining a three-dimensional model of each illuminated part of a jaw from the set of acquired image signals. 7. Apparatus according to claim 6, characterized in that it comprises:means of reconstructing a three-dimensional model of a jaw from the three-dimensional models of the different parts of a jaw; andmeans of identifying, from the three-dimensional model reconstructed in this way, a trajectory which the assembly comprising first image acquisition surface and generator will have to follow during the subsequent production of a panoramic image of the jaw. 8. Apparatus according to claim 7, characterized in that the means of identifying a trajectory from the reconstructed three-dimensional model comprise means of thresholding or segmenting the data constituting this three-dimensional model. 9. Apparatus according to claim 4, characterized in that each first, second and third image acquisition surface of the said at least one sensor is an array of pixels or a sub array of pixels, and the means of acquiring several image signals comprise means of reading the data captured by the array or the sub array of pixels, said reading means comprising means of grouping the pixels according to a predetermined number of pixels for the purpose of reading the pixels grouped in this way. 10. Apparatus according to claim 1, characterized in that the collimation device comprises three collimation slits of different forms which are each able to be positioned, on command, in front of the emission window in order to collimate the radiation in an appropriate manner. 11. Apparatus according to claim 1, characterized in that the collimation device comprises a mobile collimation slits support which is able to position, under the action of positioning means, a form of collimation slit in front of the window emitting X-radiation. 12. Apparatus according to claim 11, characterized in that the collimation slits support is able to pivot under the action of the positioning means. 13. Apparatus according to claim 1, characterized in that the collimation device comprises a collimation slit and means of adjusting the dimensions of the slit in order to give it at least some of the three forms of collimation slit used in the three respective positions of the apparatus. 14. Apparatus according to claim 13, characterized in that the adjustment means are means of adjusting the elongation of the slit in directions perpendicular to each other. 15. Apparatus according to claim 14, characterized in that the adjustment means are independent as regards the directions. 16. Apparatus according to claim 1, characterized in that the collimation slit is delimited by four edges (58, 60, 62, 64) and the adjustment means are able to displace each of the edges independently of one another. 17. Apparatus according to claim 1, characterized in that each first, second and third image acquisition surface of the said at least one sensor is an array of pixels or a sub array of pixels. 18. Apparatus according to claim 1, characterized in that the first and second image acquisition surfaces form part of a first and a second sensor respectively. 19. Apparatus according to claim 18, characterized in that it comprises a mobile unit (20) comprising the two sensors and which is able to position, on command, opposite the generator, each of the two sensors in order that it receives the X-radiation collimated by a collimation slit of appropriate form. 20. Apparatus according to claim 1, characterized in that the first, second and third image acquisition surfaces form part of a single sensor. 21. Method for producing a panoramic image of a patient's jaw from a dental radiology apparatus comprising:a generator (18) provided with a window (18b) emitting X-radiation and a collimation device positioned in front of said window in order to collimate the radiation in a suitable manner using several forms of collimation slits,at least one sensor (20a, 20b) comprising a first image acquisition surface elongated along a Z-axis perpendicular to a plane P and being used in a first position of the apparatus to produce a panoramic image of a jaw placed between the generator and the first image acquisition surface, the panoramic image being produced from the X-radiation collimated by a first form of collimation slit (22a) elongated along the Z-axis and received by the first sensor image acquisition surface and by displacement of the generator and of said first surface along a given trajectory in the plane P combined with a rotation about an axis parallel to the Z-axis, the said at least one sensor comprising a second image acquisition surface used in cone beam tomographic mode, in a second position of the apparatus, to produce a three-dimensional model of only a part of the jaw from the X-radiation collimated by a second form of collimation slit (22b) and received by the second image acquisition surface and by displacement of the generator and of said second surface in rotation about an axis parallel to the Z-axis, the second form of collimation slit having dimensions matched to those of the second image acquisition surface, characterized in that the method comprises, in a third position of use of the apparatus in cone beam tomographic mode, the following preliminary steps in order to obtain a trajectory which will be travelled in the plane P, by the assembly comprising generator and first image acquisition surface, in the first position of use of the apparatus for the production of a panoramic image of the jaw:positioning (S1 ), in front of the window emitting X-radiation, of a third form of collimation slit (22c) elongated in a direction parallel to the plane P and the longitudinal dimension of which in this direction is matched to the dimension of the second image acquisition surface in this same direction,positioning (S2), opposite the third form of collimation slit oriented in this way, of a third image acquisition surface corresponding to a part of the second surface along the Z-axis, for the purpose of cooperation of the third form of slit and the third surface. 22. Method according to claim 21, characterized in that it comprises, following the positioning steps, a step of obtaining in cone beam tomographic mode a predetermined number of solid images each representing a different part of a jaw from the assembly comprising third image acquisition surface and generator provided with the third form of collimation slit elongated parallel to the plane P. 23. Method according to claim 22, characterized in that each first, second and third image acquisition surface of the said at least one sensor is an array of pixels or a sub array of pixels, and the predetermined number of three-dimensional models depends in particular on the size of the array or the sub array of pixels of the third image acquisition surface. 24. Method according to claim 21, characterized in that it comprises the following steps:a) positioning (S4) in the plane P, about a fixed axis parallel to the Z-axis, of the assembly comprising third image acquisition surface and generator provided with the third form of collimation slit elongated parallel to the plane P;b) driving in rotation (S5) of the assembly comprising third image acquisition surface and generator about the fixed axis of rotation;c) acquisition (S6) of several image signals of a part of a jaw illuminated by the radiation collimated by the third form of slit oriented parallel to the plane P for a plurality of angular positions occupied by the assembly comprising third image acquisition surface and generator during the rotation movement. 25. Method according to claim 24, characterized in that it comprises the following steps:positioning of the assembly comprising third image acquisition surface and generator provided with the third form of collimation slit elongated parallel to the plane P about another fixed axis parallel to the Z-axis andrealization of steps b) and c) for the acquisition of the image signals of another illuminated part of the jaw. 26. Method according to claim 24, characterized in that it comprises a step of obtaining, from the set of acquired image signals, a three-dimensional model of each illuminated part of the jaw. 27. Method according to claim 26, characterized in that it comprises the following steps:reconstruction (S12) of a three-dimensional model of a jaw from the three-dimensional models of different parts of a jaw;identification (S14), from the three-dimensional model reconstructed in this way, of a trajectory which the assembly comprising first image acquisition surface and generator will have to follow during the subsequent production of a panoramic image of the jaw. 28. Method according to claim 27, characterized in that the identification of a trajectory from the reconstructed three-dimensional model comprises a step (S13) of thresholding or segmenting the data constituting this three-dimensional model. 29. Method according to claim 24, characterized in that each first, second and third image acquisition surface of the said at least one sensor is an array of pixels or a sub array of pixels, and the acquisition of several image signals comprises a step of reading the data captured by the array or the sub array of pixels which comprises a grouping of the pixels according to a predetermined number of pixels for the purpose of reading the pixels grouped in this way. 30. Method according to claim 21, characterized in that it comprises the following steps:positioning (S16), in front of the window emitting X-radiation, of the first form of collimation slit elongated along the Z-axis,positioning (S17) of the first image acquisition surface opposite the first form of collimation slit oriented in this way,control of the displacement of the assembly formed of the generator provided with the first form of collimation slit and the first image acquisition surface arranged parallel to the axis (Z) along the trajectory previously obtained combined with a rotation movement about an axis parallel to the axis (Z),acquisition of a panoramic image of the jaw during this controlled displacement combined with a shift of the pixels of the first image acquisition surface. 31. Method according to claim 21, characterized in that the collimation device comprises three collimation slits of different forms and the positioning of each of them in front of the emission window is carried out by displacement from a home position placed outside the radiation that has come from the generator. 32. Method according to claim 21, characterized in that the collimation device comprises a collimation slit and the positioning, in front of the emission window, of a different form of collimation slit is carried out by adjusting the dimensions of the slit. 33. Method according to claim 32, characterized in that the adjustment more particularly comprises the adjustment of the elongation of the slit in directions perpendicular to each other. 34. Method according to claim 21, characterized in that each first, second and third image acquisition surface of the said at least one sensor is an array of pixels or a sub array of pixels. 35. Method according to claim 21, characterized in that the first and second image acquisition surfaces form part of a first and a second sensor respectively. 36. Method according to claim 35, characterized in that the positioning of a sensor opposite the generator is carried out by displacement of said sensor. 37. Method according to claim 21, characterized in that the first, second and third image acquisition surfaces form part of a single sensor.