Method and apparatus for generating panoramic layer images

Abstract

The invention relates to a device and a method for generating panoramic layer images (1, 2) of an object (3) to be imaged by employing a 2D panoramic X-ray device, wherein the object is imaged by projecting X-rays (6) generated by an X-ray source (7) in projection directions (8) through the object (3) and recording the X-rays (6) with an X-ray detector (9), wherein several 2D X-ray projection images are recorded continuously from various imaging directions while the X-ray source (7) and the X-ray detector (9) are moved around the object (3), wherein at least one panoramic layer image (1, 2) is calculated from the recorded 2D X-ray projection images by means of a reconstruction method. The panoramic layer image (2) is calculated by selecting at least two 2D X-ray projection images (51) with respect to an active sensor area (73) and employing at least one local region (50, 52, 55, 57, 65).

Description

TECHNICAL FIELD

[0001] The present invention relates to a device and a method for generating a panoramic layer image of an object to be imaged, wherein the object is imaged by projecting X-rays generated by an X-ray source in projection directions through the object and recording the X-rays with an X-ray detector, wherein several 2D X-ray projection images are recorded continuously from various imaging directions while the X-ray source and the X-ray detector are moved around the object, wherein at least one panoramic layer image is calculated from the recorded 2D X-ray projection images by means of an algorithm. BACKGROUND

[0002] Several methods for generating panoramic layer images are known from the prior art.

[0003] WO 2015092119 A1 and US 20150164446 A1 relate to the generation of a digital dental panoramic layer image from a plurality of frame images acquired from various scanning directions around a patient's head during a dental panoramic imaging scan. The panoramic image is calculated by using information about the position and orientation of the X-ray source and the X-ray detector at certain points in time.

[0004] DE 102008008733 A1 discloses a method for generating a virtual panoramic layer image from a 3D volume, wherein an object to be imaged is virtually irradiated with a virtual X-ray source and the virtually generated image is recorded with a virtual detector. Non-desired structures can be removed during the virtual irradiation.

[0005] The disadvantage of this method is that the panoramic image is corrected based on a complex procedure for taking into account unwanted structures, in particular a 3D volume is required to virtually irradiate the object as desired.

[0006] Therefore, the calculation of a virtual panoramic layer image requires a 3D volume from which the object of interest is virtually irradiated. The resolution of the virtual panoramic layer image is usually lower than that of a classic panoramic layer image; further artifacts occur. The preparation of the 3D volume usually requires a higher radiation dose.

[0007] DE 10016678 A1 discloses a method of irradiating an object, wherein the object under examination is irradiated such that interfering, highly absorbent objects, such as metal fillings, minimize the interference with the imaging of the opposite half of the jaw.

[0008] EP 0 279 294 A1 discloses a dental X-ray diagnostic apparatus for preparing a panoramic layer image of a patient's jaw. The specified method allows rendering a layer in the object, the center of which is usually the patient's jaw. The panoramic layer image is prepared by moving the radiation source-detector arrangement around the imaged object and clocking the CCD detector lines at a frequency that varies relative to the speed of motion, so as to generate a layer image by blurring the parts that are outside the focused layer.

[0009] The disadvantage of the specified method is that the correction of the panoramic layer image for unwanted overlaps is usually very complex or completely impossible.

[0010] The object of the present invention is to provide a method for generating a panoramic layer image that can adjust parameters and thus the image in a direct manner in order to avoid repeated imaging and to improve the diagnostic capability. SUMMARY

[0011] The present invention relates to an apparatus and a method for generating a panoramic layer image of an object to be imaged by employing a 2D panoramic X-ray device, wherein the object is imaged by projecting X-rays generated by an X-ray source in a radiation direction through the object and recording the X-rays with an X-ray detector, wherein several 2D X-ray projection images are recorded continuously from various imaging directions while the X-ray source and the X-ray detector are moved around the object, wherein at least one panoramic layer image is calculated from the recorded 2D X-ray projection images by means of a reconstruction method. The panoramic layer image is calculated by selecting at least one partial area of at least two 2D X-ray projection images relative to the active sensor area and using it for the calculation.

[0012] The panoramic layer image is a two-dimensional X-ray image of the upper and / or lower jaw recorded with a 2D panoramic X-ray device. The panoramic X-ray device can for example comprise an imaging unit with an X-ray detector, wherein the movement of the X-ray detector around the patient's head during the imaging process is described. The X-ray source is moved synchronously around the patient's head on the opposite side. The X-ray source is designed to radiate a spatially limited X-ray beam which extends for example from a width of about 0.25 mm to a width of about 3 mm at the X-ray detector. This beam illuminates the jaw portion of the subject, so that the 2D X-ray projection images of the different jaw portions of the entire jaw are recorded frame by frame on the X-ray detector. Then, the panoramic layer image is calculated from the recorded 2D X-ray projection images using a reconstruction method by assembling or computationally modeling the individual 2D X-ray projection images. The process of assembling the individual 2D X-ray projection images generates a focal layer of the panoramic layer image which clearly shows the anatomical structures located therein. This focal layer usually comprises the main anatomical structures of the upper and / or lower jaw, such as teeth, tooth roots and jaw bones. The position / shape of the focal layer is determined by the path observed by the X-ray detector and the X-ray source with respect to the imaging subject. The anatomical structures not in the focal layer produce shadows and are blurred out. Thus, the position of the focal layer is determined by the path and the movement observed by the X-ray detector and by the X-ray source with respect to the scanning subject, wherein the width of the focal layer is also determined by the width of the illumination area of the X-ray detector and / or the width of the particular 2D X-ray projection image. When adjusting the beam to the width of the X-ray detector at the same time, a narrower width of the X-ray detector leads to a wider focal layer and a wider X-ray detector leads to a narrower focal layer.

[0013] Thus, the present method not only calculates the panoramic layer image by using the complete 2D X-ray projection images related to the size of the active sensor, but also performs this calculation by selecting and using only at least a partial area of these 2D X-ray projection images. Thus, by selecting at least one partial area, a smaller arbitrarily shaped X-ray detector is substantially simulated.

[0014] An advantage of the method is that selecting at least one partial area of the individual 2D X-ray projection images allows the width of the focal layer and the angle of radiation to be influenced by predetermined criteria. Thus, the individual partial areas of the 2D X-ray projection images can be selected so that the adverse overlap within the focal layer of the panoramic layer image, for example of teeth and / or dental crowns, is reduced and the main anatomical structures, such as teeth and tooth roots, are better rendered.

[0015] A further advantage of the method is that performing the method does not require a novel device, but can instead be based on a conventional 2D panoramic X-ray device, wherein only the software is used to select at least one partial area of the recorded 2D X-ray projection images in order to calculate the second panoramic layer image.

[0016] Another advantage of the method is that limiting the projection information used for reconstructing the panoramic layer image allows opening the interdental contacts, thereby improving the diagnostic capabilities of the dentist and reducing the number of repeated imaging procedures.

[0017] The X-ray detector can for example comprise a CMOS detector or a direct conversion detector with a width from 1 cm to 4 cm.

[0018] When the X-ray detector is moved around the object, for example 300 to 5000 2D X-ray projection images can be recorded. This involves for example recording 50-1000 2D X-ray projection images per second.

[0019] The size of the local area can advantageously comprise at most 80% of the particular 2D X-ray projection image.

[0020] As a result, a relatively large local area of the 2D X-ray projection image is selected. The at least one local area can then comprise various shapes, such as individual vertical strips, diagonal oriented strips, or strips with a variable width. When several local areas are used, these can be positioned arbitrarily with respect to each other, for example with a horizontal offset. Several local areas of an individual 2D X-ray projection image can for example be several parallel vertical strips.

[0021] Thus, selecting a smaller local area of a side of the particular 2D X-ray projection image increases the width of the focal layer and correspondingly shifts the main radiation direction. Local areas with a variable width also allow the width of the focal layer to vary locally within the panoramic layer image.

[0022] Advantageously, the size of the at least one local area can comprise at most 40% of the active area of the particular 2D X-ray projection image.

[0023] As a result, a relatively small local area is selected and used for calculating the panoramic layer image, thereby changing or manipulating the panoramic layer image with greater effect.

[0024] Advantageously, a weighting function can be applied to the image data of the at least one selected local area, wherein the weighted local area is used for calculating the panoramic layer image.

[0025] A Gaussian function can for example be used as the weighting function. The image data in the center of the selected local area is then assigned a higher weight than the peripheral regions.

[0026] Advantageously, the local area can be a local strip with a fixed width or a variable width.

[0027] By selecting vertical partial strips, each 2D X-ray projection image can for example be divided into 40 partial strips, which can also be arranged overlapping, so that for each individual partial strip a separate panoramic layer image with a deviating main radiation direction can be calculated. Thus, for example, 40 different panoramic layer images with variable main radiation directions can then be calculated from the same 2D X-ray projection image.

[0028] For partial strips with variable width, for example, the width can be reduced in the upper and lower regions of the partial strip and widened in the central region of the partial strip, so that the width of the focal layer in the second panoramic layer image in the central regions of the two jaws, for example in the occlusal region, is reduced, thus showing the focused teeth in particular. The width of the focal layer is greater in the upper and lower regions of the panoramic layer image, so that objects arranged in the focal layer, such as the jaw bones and the tooth roots, are shown with a smaller spacing, since other adjacent anatomical structures are also located within the focal layer, thus becoming more easily recognizable.

[0029] Advantageously, the at least one partial region can be selected manually by the user or automatically by employing an algorithm.

[0030] Thus, the user can manually select the at least one partial region. The user can for example directly determine the at least one partial region, wherein then based on these inputs, the corresponding partial region within the 2D X-ray projection image is automatically selected by the computer. The user can also define a desired main radiation direction, for example in the contact region between two teeth, wherein the required partial region for the reconstruction is then automatically determined by the computer in order to adjust the main radiation direction.

[0031] The partial region can also be selected completely automatically, wherein the position / shape and width of the focal layer and the arrangement of the main radiation direction on the contact points between the individual teeth are determined automatically based on a reference head or based on prior knowledge, such as a 3D model of the upper jaw and / or the lower jaw, wherein the partial region is then determined based on these inputs in order to calculate the desired panoramic layer image.

[0032] Advantageously, selecting the at least one partial region within the 2D X-ray projection image allows to vary the width of the focal layer of the calculated panoramic layer image.

[0033] Selecting the partial region influences the width of the focal layer.

[0034] Advantageously, selecting the at least one partial region within the 2D X-ray projection image allows to adjust at least one main radiation direction of a particular 2D X-ray projection image to the associated position of the focal layer of the calculated panoramic layer image and thus to adjust the main radiation direction to the associated position of the focal layer of the calculated panoramic layer image.

[0035] The main radiation direction of the computed panoramic layer image is then adjusted by selecting at least one local region. For example, if a local strip is selected on the left side of the 2D X-ray projection image at the contact point between two molars and a panoramic layer image is computed from the selected local strip, the main radiation direction at the contact location between the two molars is also shifted. In this way, for example, an opening can occur on the specific interdental contact at the contact point between the two molars, thereby minimizing the overlap of the molars in the panoramic layer image.

[0036] Advantageously, the main radiation direction of a specific 2D X-ray projection image and thus of the focal layer can be adjusted and / or the width of the focal layer can be adjusted depending on the anatomy of the object to be imaged.

[0037] The main radiation direction and the width of the focal layer are thus adjusted depending on the anatomy of the object to be imaged, i.e. the two jaws. For this purpose, for example, a 3D model from the optical 3D image of the two jaws can be relied on, wherein the width and the main radiation direction of the focal layer at the contact point between the teeth can be determined depending on the shape and extent of the upper and / or lower jaw.

[0038] Advantageously, the adjustment of the main radiation direction of a specific 2D X-ray projection image and thus of the focal layer can be made towards an opening of an interdental contact, wherein the contact point between the teeth is determined and predefined, and an appropriate central optimum radiation direction is determined for the specific location of the focal layer, so that the teeth have the lowest possible overlap or no overlap in the specific contact point within the computed panoramic layer image.

[0039] Thereby, certain optimum radiation directions are determined for each contact point between the teeth and a second panoramic layer image is computed therefrom, wherein the overlap of the teeth at the contact points is minimized as far as possible.

[0040] Advantageously, the first panoramic layer image can be computed from each 2D X-ray projection image, wherein the complete image information of the complete active sensor area of the 2D X-ray projection image is used for the computation, wherein the second panoramic layer image is computed from a selected local region of the 2D X-ray projection image.

[0041] Thereby, the first panoramic layer image is computed from the complete 2D X-ray projection image, wherein the second panoramic layer image is computed from a selected local region.

[0042] Advantageously, the difference between the actual radiation direction of the first panoramic layer image and the optimum radiation direction of the second panoramic layer image can be used to automatically determine tooth misalignments and to highlight these misalignments in a graphical rendering of the first and / or second panoramic layer image.

[0043] The difference between the actual radiation direction of the panoramic layer image and the optimal radiation direction of the second panoramic layer image is thus indicated, so that it becomes clear in which position to change the radiation direction to reduce the overlap between the teeth at the contact point.

[0044] The optimal radiation direction on the interdental contact and / or the contact point between the individual teeth can be determined manually by the user or automatically by the computer, wherein the individual teeth can be segmented and the specific contact point can be analyzed. This involves determining the optimal radiation direction that makes the possible lowest overlap of the contact point teeth in the calculated second panoramic layer image along the range of the radiation beam of the X-rays of the individual 2D X-ray projection images.

[0045] Advantageously, the user can employ a control device to switch between the graphical rendering of the first panoramic layer image and the second panoramic layer image.

[0046] The user can thus arbitrarily switch between the first panoramic layer image and the second panoramic layer image. The first panoramic layer image and the second panoramic layer image can also be displayed simultaneously with the display device.

[0047] Advantageously, the user can use a control device to select a region in the graphical rendering of the first panoramic layer image, wherein a magnified rendering of this region from the second panoramic layer image is superimposed in the manner of a magnifying glass function.

[0048] The user can thus select a certain region in the first panoramic layer image, such as a certain contact point between two teeth, so that this region is superimposed from the second panoramic layer image with the interdental contact open in the manner of a magnifying glass function. In this way, the user is then shown a conventional panoramic layer image with the additional function of allowing the opening of the interdental contact on the contact point with overlap.

[0049] The invention also relates to a device for carrying out the aforementioned method, which device comprises a computer, an X-ray source, an X-ray detector, a support arm for moving the X-ray source and the X-ray detector around the object to be imaged. In this case, the X-ray detector has a width of at least 5 mm, wherein the computer employs a selection algorithm to select at least one partial region in the 2D X-ray projection images and then employs a calculation algorithm to calculate the panoramic layer image.

[0050] The device for carrying out the aforementioned method thus comprises the elements of a conventional 2D panoramic X-ray device and a computer. The X-ray detector can also have a width of between 5 mm and 40 mm, so that the position of the partial region can be selected with greater flexibility.

[0051] The advantage of the apparatus is that only at least two conventional, corresponding 2D X-ray projection images and a computer of the panorama layer image are sufficient to perform the present method. In this case, the software only performs the selection of at least one local region in the 2D X-ray projection images and the calculation of the second panorama layer image. BRIEF DESCRIPTION OF DRAWINGS

[0052] The application is explained based on the drawings. These show

[0053] Figure 1 is a schematic diagram for illustrating an embodiment of the present method,

[0054] Figure 2 is a schematic diagram of the magnifying glass function of the second virtual tool,

[0055] Figure 3 is a schematic diagram of a 2D X-ray projection image with a local strip,

[0056] Figure 4 is a schematic diagram of a 2D X-ray projection image with a diagonal local strip,

[0057] Figure 5 is a schematic diagram of a 2D X-ray projection image with two local strips,

[0058] Figure 6 is a schematic diagram of a 2D X-ray projection image with a local strip of variable width,

[0059] Figure 7 is a schematic diagram of an X-ray detector comprising a frame and a sensor area. DETAILED DESCRIPTION

[0060] Figure 1 A schematic diagram for illustrating an embodiment of the present application for generating a first panorama layer image 1 and a second panorama layer image 2 of an imaged object 3 is shown, wherein a beam of X-rays 6 irradiating the jaw 4 of a patient's head 5 is generated by an X-ray source 7, which is represented in dashed lines, wherein the object is irradiated along a main radiation direction 8 of the beam of X-rays 6. The X-rays 6 then hit an X-ray detector 9, such as a CMOS detector, and are recorded by the latter. During the imaging process, the X-ray detector 9 is moved continuously, for example, around the object 3, as indicated by arrow 10. This involves recording individual 2D X-ray projection images from different imaging directions and / or main radiation directions. In synchronicity with the X-ray detector 9, the X-ray source 7 is mounted on the opposite side and is correspondingly moved along a circular path around the patient's head 5, as indicated by arrow 11.

[0061] For example, 500 2D X-ray projection images can be recorded in the course of the circular path 10. For example, the main radiation direction 8 can be calculated as an average of the individual directions of the beam of X-rays 6. Then, using the individual 2D X-ray projection images, a first panoramic layer image 1 is calculated, in which the complete image information related to the active sensor area of the X-ray detector 9 is used.

[0062] In order to open the overlapping interdental contacts, the available 3D model of the patient's head 5 can be analyzed, in which the individual teeth 12 of the upper and / or lower jaw 4 are segmented and the optimal optimal radiation directions at the contact points are determined. On a first contact point 13 between the front teeth 14, the overlapping of the teeth exists in the first panoramic layer image 1, as indicated by the arrow 15. A first central optimal radiation direction 17 is then determined by the computer 16. A second optimal radiation direction 19 is determined on a second contact point 18. A third optimal radiation direction 21 is determined on a third contact point 20. Then, based on the specified optimal radiation directions 17, 19 and 21 and based on the position / shape of the focal layer 22, the computer 16 calculates a selection of local areas of 2D X-ray projection images, so that from the selected local areas the second panoramic layer image 2 is calculated. The second panoramic layer image 2 shows in particular that the interdental contact on the first contact point 13 between the front teeth 14 is opened, on the second contact point 18 and on the third contact point 20, as indicated by the arrows 24, 25 and 26. The overlapping of the teeth on the contact points is reduced as far as possible. Data input devices such as a keyboard 27 and a mouse 28 are connected to the computer 16. A display device 29 such as a monitor is also connected to the computer 16 in order to render the calculated first panoramic layer image 1 and the second panoramic layer image 2 graphically. The user can navigate within the panoramic layer images 1 and 2 by means of a cursor 30 with the data input devices 27 and 28. By means of a first virtual tool 31, the user can switch back and forth between the rendering of the first panoramic layer image 1 and the second panoramic layer image 2. By means of a second virtual tool 32, the user can use a magnifying glass function, in which the user can select a certain area in the first panoramic layer image 1, such as the contact points 13, 18 and 20, which is rendered enlarged from the second panoramic layer image 2.

[0063] Figure 2 It is shown Figure 1Fig. 6 shows a schematic view of the magnifying glass function of the second virtual tool 32 in the program, wherein the user selects a first overlap region 40 in the first panoramic layer image 1 at the position of the first contact point 13, which is rendered magnified from the second panoramic layer image 2 as a portion 41. Correspondingly, a second overlap region 42 is selected at the position of the second contact point 18 and rendered as a second portion 43. Subsequently, a third overlap region 44 is selected at the position of the third contact point 20 and rendered magnified as a third portion 45. The magnified portions 41, 43 and 45 clearly show that the interdental contacts are opened at the contact points 13, 18 and 20, so that the overlap within the first panoramic layer image 1 of the teeth is reduced.

[0064] Figure 3 Fig. 5 shows a schematic view of a 2D X-ray projection image 51 of the X-ray detector 9, wherein a selected partial region 50, indicated by a dashed line, is arranged on the left edge of the 2D X-ray projection image 51. The second panoramic layer image 2 is thereby calculated only by using the selected partial region 50 of each 2D X-ray projection image 51. As a result, the main radiation direction will also be shifted. Within the 2D X-ray projection image 51 of the X-ray detector 9, other partial strips can also be selected, which can also overlap, for example, in order to calculate other panoramic layer images. The 2D X-ray projection image 51 of the X-ray detector 9 can be divided into 40 parallel partial strips, for example, so that 40 different panoramic layer images can be calculated. In an embodiment, the user can then scroll through the various panoramic layer images, wherein the radiation direction changes accordingly. In this way, it is then possible to graphically trace back the opening of the interdental contacts. The user can then manually select a suitable panoramic layer image with sufficiently opened interdental contacts.

[0065] Figure 4 Fig. 6 shows a schematic view of the magnifying glass function of the second virtual tool 32 in the program, wherein the user selects a first overlap region 40 in the first panoramic layer image 1 at the position of the first contact point 13, which is rendered magnified from the second panoramic layer image 2 as a portion 41. Correspondingly, a second overlap region 42 is selected at the position of the second contact point 18 and rendered as a second portion 43. Subsequently, a third overlap region 44 is selected at the position of the third contact point 20 and rendered magnified as a third portion 45. The magnified portions 41, 43 and 45 clearly show that the interdental contacts are opened at the contact points 13, 18 and 20, so that the overlap within the first panoramic layer image 1 of the teeth is reduced.

[0066] Figure 5A schematic diagram of another embodiment is shown, in which the selected local region comprises a first local strip 55 in an upper region 56 of the 2D X-ray projection image 51 and a second local strip 57 in a lower region 58 of the 2D X-ray projection image 51. In this way, the main radiation direction in the upper region of the 2D X-ray projection image 51, i.e. in the region of the upper jaw, is shifted to the left, whereas the main radiation direction in the lower region of the 2D X-ray projection image 51, i.e. in the region of the lower jaw, is essentially kept unchanged with respect to the initial main radiation direction of the 2D X-ray projection image 51. A first width 59 of the first local strip 55 and a second width 60 of the second local strip 57 define the width of the focal layer 22 in the computed second panoramic layer image 2.

[0067] Figure 6 A further embodiment is shown, in which the shape of the selected local region is a strip 65 with a variable width, wherein in a central region 61 of the 2D X-ray projection image 51, a first width 62 is dimensioned larger than a second width 63 in an upper region of the 2D X-ray projection image 51 and a third width 64 in a lower region of the 2D X-ray projection image 51. Thus, the focal layer 22 in the second panoramic layer image 2 is narrower in the central region than in the upper or lower regions. Accordingly, teeth in the central region can be rendered with a greater separation from foreign object structures than objects in the upper and lower regions.

[0068] Figure 7 A schematic diagram of an X-ray detector 9 is shown, which comprises a frame 70 and a sensor region 71, wherein the sensor region 71 comprises unused and / or inactive regions 72 and used and / or active sensor regions 73. Thus, the 2D X-ray projection image 51 is recorded with the active sensor regions 73. From the image data of the recorded 2D X-ray projection image 51, a partial region 50 is selected, which is shown as a dashed line. The active sensor regions 73 can also have the same size as the sensor region 71. Thereby, in such an embodiment, there are no inactive sensor regions 72.

[0069] Reference Signs

[0070] 1 first panoramic layer image

[0071] 2 second panoramic layer image

[0072] 3 imaged object

[0073] 4 jaw

[0074] 5 patient head

[0075] 6 radiation beam of X-rays

[0076] 7 X-ray source

[0077] 8 radiation direction of the radiation beam

[0078] 9 x-ray detector

[0079] 10 arrow for the circumferential path of the x-ray detector

[0080] 11 arrow for the circumferential path of the x-ray source

[0081] 12 individual teeth of the jaw

[0082] 13 first contact point of the incisor

[0083] 14 incisor

[0084] 15 overlapping arrows rendering the teeth

[0085] 16 computer

[0086] 17 first central optimal radiation direction

[0087] 18 second contact point of the incisor

[0088] 19 second optimal radiation direction

[0089] 20 third contact point of the incisor

[0090] 21 third optimal radiation direction

[0091] 22 width of the focusing layer

[0092] 23 area of the molar

[0093] 24 arrow

[0094] 25 arrow

[0095] 26 arrow

[0096] 27 keyboard

[0097] 28 mouse

[0098] 29 display device

[0099] 30 cursor

[0100] 31 first virtual tool

[0101] 32 second virtual tool

[0102] 40 first area

[0103] 41 enlarged portion of the first area

[0104] 42 second area

[0105] 43 enlarged portion of the second region

[0106] 44 third region

[0107] 45 enlarged portion of the third region

[0108] 50 selected partial region

[0109] 51 2D X-ray projection image

[0110] 52 selected partial region

[0111] 53 upper region of the partial strip

[0112] 54 lower region of the partial strip

[0113] 55 first partial strip

[0114] 56 upper region of the 2D X-ray projection image

[0115] 57 second partial strip

[0116] 58 lower region of the 2D X-ray projection image

[0117] 59 first width of the first partial strip

[0118] 60 second width of the first partial strip

[0119] 61 central region of the 2D X-ray projection image

[0120] 62 first width in the upper region of the 2D X-ray projection image

[0121] 63 second width in the upper region of the 2D X-ray projection image

[0122] 64 third width in the lower region of the 2D X-ray projection image

[0123] 65 strip with variable width

[0124] 70 frame

[0125] 71 sensor region

[0126] 72 unused and / or inactive sensor region

[0127] 73 used and / or active sensor region

Claims

1. A method for generating a panoramic layer image of an object (3) to be imaged using a 2D panoramic X-ray device, wherein the panoramic layer image comprises a first panoramic layer image (1) and a second panoramic layer image (2), wherein the object (3) is imaged by projecting X-rays (6) generated by an X-ray source (7) through the object (3) in a radiation direction (8) and recording the X-rays with an X-ray detector (9), wherein several 2D X-ray projection images are continuously recorded from various imaging directions while the X-ray source (7) and the X-ray detector (9) move around the object (3), wherein at least one second panoramic layer image (2) is calculated from the recorded 2D X-ray projection images by means of a reconstruction method, characterized in that, The second panoramic image (2) is calculated by selecting and using at least one local region (50, 52, 55, 57, 65) from at least two 2D X-ray projection images (51) relative to the active sensor region (73), wherein selecting the at least one local region (50, 52, 55, 57, 65) within the 2D X-ray projection image (51) allows for a change in the width of the focusing layer (22) of the calculated panoramic image (2), and wherein, based on the imaging anatomy (4) of the object (3), by selecting the at least one local region (50, 52, 55, 57, 65), the main radiation direction (8) of a particular 2D X-ray projection image (51) is adjusted, and thus the central local radiation direction of the focusing layer (22) and / or the width of the focusing layer (22) are adjusted.

2. The method according to claim 1, characterized in that, The size of the at least one local region (50, 52, 55, 57, 65) is no greater than 80% or 40% of the specific 2D X-ray projection image (51).

3. The method according to claim 1, characterized in that, A weighting function is applied to the image data of the selected at least one local region (50, 52, 55, 57, 65), wherein the weighted local region is used to calculate the second panoramic layer image (2).

4. The method according to any one of claims 1 to 3, characterized in that, The at least one local region is a local strip (50, 52, 55, 57, 65) with a fixed width (59, 60) or a variable width (62, 63, 64).

5. The method according to any one of claims 1-3, characterized in that, The at least one local region (50, 52, 55, 57, 65) is predefined for all 2D X-ray projection images (51) regarding its position relative to the sensor region (73) being actively irradiated, regarding its size, and regarding its shape, or it is variable for different 2D X-ray projection images (51).

6. The method according to any one of claims 1-3, characterized in that, The at least one local region (50, 52, 55, 57, 65) is selected manually by the user or automatically by using an algorithm.

7. The method according to any one of claims 1 to 3, characterized in that, Selecting at least one local region (50, 52, 55, 57, 65) within a 2D X-ray projection image (51) causes at least one main radiation direction (8) of a particular 2D X-ray projection image to be adjusted to the associated local position of the focal layer (22) of the calculated second panoramic layer image (2), and thus the main radiation direction is adjusted to the associated local position of the focal layer (22) of the calculated second panoramic layer image (2).

8. The method according to claim 1, characterized in that, By selecting local regions (50, 52, 55, 57, 65), the main radiation direction (8) of a specific 2D X-ray projection image (51) is adjusted, and thus the main radiation direction of the focusing layer (22) is adjusted to the opening of the interdental contact, wherein the contact points (13, 18, 20) between the teeth (14) are determined and predefined, and an appropriate central optimal radiation direction (17, 19, 21) is determined for a specific location of the focusing layer (22), such that the teeth (14) have as little overlap as possible or no overlap at the specific contact points (13) within the calculated second panoramic layer image (2).

9. The method according to any one of claims 1-3, characterized in that, The first panoramic layer image (1) is calculated from each of the 2D X-ray projection images (51), wherein the complete image information of the 2D X-ray projection images (51) is used for the calculation, and the second panoramic layer image (2) is calculated from each of the selected local regions (50, 52, 55, 57, 65) of the 2D X-ray projection images (51).

10. The method according to claim 9, characterized in that, The difference between the actual radiation direction (8) of the first panoramic layer image and the optimal radiation direction (17, 19, 21) of the second panoramic layer image (2) is used to automatically identify overlapping tooth regions in the graphic rendering of the first panoramic layer image and / or the second panoramic layer image and to graphically highlight the overlapping tooth regions.

11. The method according to claim 9, characterized in that, The user uses the first control device (31) to switch between the graphics rendering of the first panoramic layer image (1) and the second panoramic layer image (2).

12. The method according to claim 9, characterized in that, The user uses a second control device (32) to select a region (40, 42, 44) in the graphic rendering of the first panoramic layer image (1), where the magnified rendering (41, 43, 45) of this region from the second panoramic layer image (2) is superimposed in a magnifying glass manner.

13. An apparatus for performing the method according to any one of claims 1 to 12, comprising a computer (16), an X-ray source (7), an X-ray detector (9), and a support arm for moving the X-ray source (7) and the X-ray detector (9) around an imaging object (3), characterized in that, The X-ray detector (9) has a sensor width for active irradiation between 5 mm and 40 mm, wherein the computer (16) employs a selection algorithm to select at least one local region (50, 52, 55, 57, 65) of the 2D X-ray projection image and uses a computational algorithm to compute a second panoramic layer image (2).

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