CN115670497B - Digital oral panorama reconstruction method based on automatic focusing - Google Patents
Digital oral panorama reconstruction method based on automatic focusing Download PDFInfo
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- 230000002159 abnormal effect Effects 0.000 claims description 5
- 238000004364 calculation method Methods 0.000 claims description 4
- 238000003384 imaging method Methods 0.000 description 5
- 210000002455 dental arch Anatomy 0.000 description 3
- 238000003745 diagnosis Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 210000000214 mouth Anatomy 0.000 description 2
- 230000001172 regenerating effect Effects 0.000 description 2
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- 208000014151 Stomatognathic disease Diseases 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 210000000887 face Anatomy 0.000 description 1
- 210000003128 head Anatomy 0.000 description 1
- 210000004373 mandible Anatomy 0.000 description 1
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Abstract
The invention relates to an automatic focusing-based digital oral panorama reconstruction method, which comprises the following steps: s1, scanning around a target object according to a scanning track to obtain multi-frame projection images; s2, according to the preset coordinate positions of the focusing surfaces, the positions of the focusing surfaces are adjusted by shifting along the beam direction, so that the coordinates of a plurality of groups of focusing surfaces are obtained; s3, reconstructing a multi-layer panoramic image according to the coordinates of a plurality of groups of focusing planes; s4, performing filtering operation on the reconstructed multi-layer panoramic image; step S5, calculating definition values of the panoramic images, and searching a definition layer of each part of the teeth based on the calculated definition values; s6, calculating offset of the coordinate of the preset focusing plane according to the layer sequence number of the clear layer where each point on each part of the teeth is located, and obtaining a new focusing plane coordinate suitable for the trend of the teeth of the patient; s7, correcting the coordinates of the new focusing surface; and S8, reconstructing based on the new focusing plane coordinates to obtain a clear image.
Description
Technical Field
The invention relates to the technical field of medical images, in particular to a digital oral panorama reconstruction method based on automatic focusing.
Background
The oral full-view film, also called a curved surface broken layer film, is an X-ray photographic image obtained by rotating a narrow-strip X-ray detector along the outside of the cheek of a patient; the oral cavity full view film can display the images of the maxilla, the mandible, the temporomandibular joint, the maxillary sinus and the full mouth teeth on one image at the same time, and has a very important role in the diagnosis of dental diseases in the dental diagnosis.
The digital panoramic reconstruction is carried out by rotating around a patient, collecting a plurality of projection data under each angle, and then reconstructing an image at any given focusing point according to the calculation of the coordinate relation; the current method for obtaining the full-view film basically comprises the steps of determining a dental arch-shaped focusing surface in advance according to priori knowledge, and then reconstructing the focusing surface according to projection data to obtain a panoramic image. This approach has problems: the fixed focusing surface cannot be suitable for each patient, when the teeth of the user are uneven or the inclination angle of the teeth is large, the teeth are imaged by the existing method, and each tooth or each structure of the teeth cannot be focused at the same time, so that some teeth are unclear in the image, which is not beneficial to diagnosis of doctors.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for automatically judging the focusing position of each tissue in an imaging range and generating a clear image.
Firstly, determining an adjusting range of a focusing layer, then reconstructing a plurality of panoramic pictures, finding out focusing positions of each tissue structure in a mode of image definition judgment, and adjusting preset focusing plane coordinates; then, a new focusing surface suitable for the dental arch trend of a specific patient is regenerated according to the adjusted offset, and a final image is reconstructed.
The invention relates to an automatic focusing-based digital oral panorama reconstruction method, which comprises the following steps:
s1, scanning around a target object according to a scanning track to obtain multi-frame projection images;
s2, according to the preset coordinate positions of the focusing surfaces, the positions of the focusing surfaces are adjusted by shifting along the beam direction, so that the coordinates of a plurality of groups of focusing surfaces are obtained;
s3, reconstructing a multi-layer panoramic image according to the coordinates of a plurality of groups of focusing planes;
s4, performing filtering operation on the reconstructed multi-layer panoramic image;
step S5, calculating definition values of the panoramic images, and searching a definition layer of each part of the teeth based on the calculated definition values;
step S6, calculating the offset of the coordinate of the preset focusing plane according to the layer sequence number of the clear layer where each point on each part of the teeth is located, and adding the offset to the coordinate point corresponding to the preset focusing plane to obtain a new focusing plane coordinate suitable for the trend of the teeth of the patient;
s7, correcting the coordinates of the new focusing surface, eliminating some abnormal values caused by noise, and enabling the new focusing surface to be continuous and free of jump;
and S8, reconstructing based on the new focusing plane coordinates to obtain a clear image.
Further, in the step S2, according to a preset coordinate position of the focusing surface, the position of each focusing surface is adjusted by shifting along the normal direction of the scanning track, so as to obtain the coordinate of the multi-focusing surface, which specifically includes the following steps:
let P be any point on the focal plane, its three-dimensional coordinates be P (x, y, z), and when the position of each focal plane is adjusted according to the offset sigma, the new coordinates P '(x', y ', z') after adjustment are:
x′＝x+σ x
y′＝y+σ y
z′＝z
wherein sigma x Sum sigma y The x, y direction offsets are shown, respectively, and the values are related to the set offset sigma and the current beam angle theta:
σ x ＝σ*cosθ
σ y ＝σ*sinθ
further, the step 5 of calculating the sharpness values of the panoramic images, and searching the sharpness layer where each tooth is located based on the calculated sharpness values specifically includes the following steps:
calculating each point f in multiple panoramic images i Gradient values of (x, y):
wherein i is more than or equal to 1 and less than or equal to N, i represents an ith Zhang Quanjing image, N is the number of pre-reconstructed panoramic images, and G is a corresponding point f i Gradient values of (x, y);
and searching a layer with the maximum gradient value in the plurality of panoramic images, namely a clear layer, recording layer sequence numbers and converting the offset corresponding to the layer.
Further, assume that the preset focal plane is shifted forward and backward along the normal line of the track for M times, and N images are reconstructed, where n=2xm+1, i ranges from [1,2 x m+1], and assuming that the difference of the shift amounts of the coordinates of two adjacent images is 1, σ ranges from [ -M, +m ]; and (3) obtaining the sigma corresponding to the point (x, y) when the gradient value is maximum based on the calculation.
Further, in the step 7, the coordinates of the new focusing surface are corrected, and abnormal values caused by noise are removed, so that the new focusing surface is continuous and has no jump;
let P be any point on the focal plane, its three-dimensional coordinates be P (x, y, z), the new coordinates after adjustment be P '(x', y ', z'), a region of m x n is selected around it, and the mean values of the x, y and z coordinates (x mean ,y mean ,z mean ) Comparing (x ', y ', z ') with the correction:
wherein threshold is a threshold.
The beneficial effects are that:
according to the digital oral panorama reconstruction method based on automatic focusing, imaging adjustment of a plurality of layers of focusing planes can be automatically carried out according to the offset, and the definition is automatically judged and the focusing planes are obtained based on a plurality of panoramic images obtained by the plurality of layers of focusing planes; and regenerating a new focusing surface suitable for the trend of the dental arch of the current patient, and reconstructing to obtain a final image, thereby ensuring that the imaging of each tooth is clear.
Drawings
Fig. 1: a method flow chart of the present invention;
fig. 2: defining a schematic diagram of a target and a scanning orbit coordinate system;
fig. 3: reconstructing an obtained image by using a preset focusing surface;
fig. 4: the obtained reconstructed image is automatically focused by the algorithm of the invention.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments, and all other embodiments obtained by those skilled in the art without the inventive effort based on the embodiments of the present invention are within the scope of protection of the present invention.
According to an embodiment of the present invention, an automatic focusing-based digital oral panorama reconstruction method is provided, as shown in fig. 1, comprising the following steps:
s1, scanning around a target object according to a scanning track to obtain multi-frame projection images;
s2, according to the preset coordinate positions of the focusing surfaces, the positions of the focusing surfaces are adjusted by shifting along the beam direction, so that the coordinates of a plurality of groups of focusing surfaces are obtained;
the definition of the direction is shown in fig. 2, the direction in which the face faces is in an X direction, the direction in which the head top extends upwards is in a Z direction, the direction in the left side of the face is in a Y direction, the Y direction is perpendicular to a plane formed by X, Z, and a X, Y, Z axis forms a vertical coordinate system;
let P be any point on the focal plane, its coordinates be denoted as P (x, y, z), then the new coordinates P '(x', y ', z') after adjustment are:
x′＝x+σ x
y′＝y+σ y
z′＝z
wherein sigma x Sum sigma y The x, y direction offsets are shown, respectively, and the values are related to the set offset sigma and the current beam angle theta:
σ x ＝σ*cosθ
σ y ＝σ*sinθ。
s3, reconstructing a multi-layer panoramic image according to the coordinates of a plurality of groups of focusing planes;
s4, performing filtering operation on the reconstructed panoramic images to eliminate the influence of noise on follow-up images;
step S5, calculating definition values of the panoramic images, and searching a definition layer of each part of the teeth based on the calculated definition values;
according to the embodiment of the invention, the specific implementation mode is as follows:
calculating each point f in the image i The gradient values of (x, y), as in equation 1,
wherein i is more than or equal to 1 and less than or equal to N, i represents an ith Zhang Quanjing image, N is the number of pre-reconstructed panoramic images, and G is the gradient value of a corresponding point;
searching a layer with the maximum gradient value at the point in a plurality of groups of images, namely a clear layer, recording layer sequence numbers and converting the offset corresponding to the layer;
according to one embodiment of the present invention, for example, 15 shifts are respectively performed on the preset focus plane forward and backward, 31 images are reconstructed, where n=31, i ranges from [1,31], and if the difference of the shift amounts of the coordinates of two adjacent images is 1, σ ranges from [ -15,15]; if the gradient value is maximum when the calculated point (x, y) is i=20, the corresponding offset sigma=4 at the moment;
step S6, calculating the offset of the coordinate of the preset focusing plane according to the layer sequence number of the clear layer where each point on each part of the teeth is located, and adding the offset to the coordinate point corresponding to the preset focusing plane to obtain a new focusing plane coordinate suitable for the trend of the teeth of the patient;
and S7, reconstructing based on the new focusing plane coordinates to obtain a clear image.
Fig. 3 is a view of an image reconstructed with a preset focus plane, and fig. 4 is a view of a reconstructed image obtained by auto-focusing with the algorithm of the present invention. By using the digital oral panorama reconstruction method based on automatic focusing, provided by the invention, the imaging adjustment of the multi-layer focusing surface can be automatically carried out according to the offset without manual operation of a user, and the definition is automatically judged and the focusing surface is obtained based on a plurality of panoramic images obtained by the multi-layer focusing surface; and regenerating a new focusing surface suitable for the trend of the dental arch of the current patient, and reconstructing to obtain a final image, thereby ensuring that the imaging of each tooth is clear.
According to an embodiment of the present invention, step 7, correcting the coordinates of the new focal plane, and eliminating some abnormal values caused by noise, so that the new focal plane is continuous and has no jump;
let P be any point on the focal plane, its three-dimensional coordinates be P (x, y, z), the new coordinates after adjustment be P '(x', y ', z'), a region of m x n is selected around it, and the mean values of the x, y and z coordinates (x mean ,y mean ,z mean ) Comparing (x ', y ', z ') with the correction:
wherein threshold is a threshold.
While the foregoing has been described in relation to illustrative embodiments thereof, so as to facilitate the understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the embodiments, but is to be construed as limited to the spirit and scope of the invention as defined and defined by the appended claims, as long as various changes are apparent to those skilled in the art, all within the scope of which the invention is defined by the appended claims.
Claims (1)
1. An automatic focusing-based digital oral panorama reconstruction method is characterized by comprising the following steps:
s1, scanning around a target object according to a scanning track to obtain multi-frame projection images;
s2, according to the preset coordinate positions of the focusing surfaces, the positions of the focusing surfaces are adjusted by shifting along the beam direction, so that the coordinates of a plurality of groups of focusing surfaces are obtained; let P be any point on the focal plane, its three-dimensional coordinates be P (x, y, z), and when the position of each focal plane is adjusted according to the offset sigma, the new coordinates P '(x', y ', z') after adjustment are:
x′＝x+σ x
y′＝y+σ y
z′＝z
wherein sigma x Sum sigma y The x, y direction offsets are shown, respectively, and the values are related to the set offset sigma and the current beam angle theta:
σ x ＝σ*cosθ
σ y ＝σ*sinθ；
s3, reconstructing a multi-layer panoramic image according to the coordinates of a plurality of groups of focusing planes;
s4, performing filtering operation on the reconstructed multi-layer panoramic image;
step S5, calculating definition values of the panoramic images, and searching a definition layer of each part of the teeth based on the calculated definition values;
step S6, calculating the offset of the coordinate of the preset focusing plane according to the layer sequence number of the clear layer where each point on each part of the teeth is located, and adding the offset to the coordinate point corresponding to the preset focusing plane to obtain a new focusing plane coordinate suitable for the trend of the teeth of the patient;
s7, correcting the coordinates of the new focusing surface, eliminating some abnormal values caused by noise, and enabling the new focusing surface to be continuous and free of jump; assuming that the preset focus plane is shifted forward and backward for M times along the normal line of the track respectively, reconstructing N images, wherein N=2×M+1, and assuming that the offset difference of coordinates of two adjacent images is 1, the range of sigma is [ -M, +M ]; based on the calculation, obtaining sigma corresponding to the point (x, y) when the gradient value is maximum;
step S5, performing sharpness calculation on a plurality of panoramic images, and searching a sharpness layer where each tooth is located based on the calculated sharpness values, specifically including the following steps:
calculating each point f in multiple panoramic images i Gradient values of (x, y):
wherein i is more than or equal to 1 and less than or equal to N, i represents an ith Zhang Quanjing image, N is the number of pre-reconstructed panoramic images, and G is a corresponding point f i Gradient values of (x, y);
searching a layer with the maximum gradient value in the point in the plurality of panoramic images, namely a clear layer, recording layer sequence numbers and converting the offset corresponding to the layer;
step S7, correcting the coordinates of the new focusing surface, eliminating abnormal values caused by noise, and enabling the new focusing surface to be continuous without jump; the method specifically comprises the following steps:
let P be any point on the focal plane, its three-dimensional coordinates be P (x, y, z), the new coordinates after adjustment be P '(x', y ', z'), a region of m x n is selected around it, and the mean values of the x, y and z coordinates (x mean ,y mean ,z mean ) Comparing (x ', y ', z ') with the correction:
wherein threshold is a threshold;
and S8, reconstructing based on the new focusing plane coordinates to obtain a clear image.
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| CN105741239A (en) * | 2014-12-11 | 2016-07-06 | 合肥美亚光电技术股份有限公司 | Method and apparatus for generating tooth panorama image, and panorama machine for shooting teeth |
| CN208910300U (en) * | 2017-11-28 | 2019-05-31 | 合肥美亚光电技术股份有限公司 | Arch form curve debugging tool for oral cavity panoramic apparatus |
| CN114159090A (en) * | 2021-12-07 | 2022-03-11 | 深圳市菲森科技有限公司 | Dental panoramic shooting device and automatic correction method |
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| US7676022B2 (en) * | 2005-05-02 | 2010-03-09 | Oy Ajat Ltd. | Extra-oral digital panoramic dental x-ray imaging system |
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| CN105741239A (en) * | 2014-12-11 | 2016-07-06 | 合肥美亚光电技术股份有限公司 | Method and apparatus for generating tooth panorama image, and panorama machine for shooting teeth |
| CN208910300U (en) * | 2017-11-28 | 2019-05-31 | 合肥美亚光电技术股份有限公司 | Arch form curve debugging tool for oral cavity panoramic apparatus |
| CN114159090A (en) * | 2021-12-07 | 2022-03-11 | 深圳市菲森科技有限公司 | Dental panoramic shooting device and automatic correction method |
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