TW201833657A - Method For Image Calibration Of X-ray Machine Based On A Movable Calibration Plate - Google Patents

Abstract

This invention provides a method for image calibration of an X-ray machine based on a movable calibration plate. The calibration plate comprises a main body and multiples calibration members. The main body includes a first plate portion and a second plate portion that are coupled and not parallel to each other. The calibration members corresponds to world coordinates respectively, and are spacingly disposed on the first plate portion and the second plate portion, such that the calibration members are not overlapped in the image of the calibration plate produced by the X-ray machine in a first orientation. The method comprises the following steps: Producing a first image of the calibration plate by the X-ray machine in the first orientation; Recognizing the calibration members and their respective corresponding image coordinates in the first image by a computing device; and calculating, by the computing device, multiple calibration parameters according to the world coordinates and the image coordinates corresponding the calibration members.

Description

X-ray machine image correction method based on movable calibration plate

The invention relates to a method for image correction of an X-ray machine, in particular to a method for performing image correction of an X-ray machine by using a movable calibration plate.

Like a general camera, the imaging mechanism of the existing X-ray machine is also suitable for description using a pinhole camera model; therefore, the image correction of the X-ray machine is also like a general camera correction, that is, obtaining a pinhole. Internal and external parameters of the camera model.

The existing X-ray image correction methods need to be corrected by using a calibration plate, and the design and setting position of the calibration plate play an important role. Referring to Fig. 1, in the conventional correction method, there is a method of fixing a correction plate 3 to the X-ray emitting portion 11 of the X-ray machine 1 by means of a metal hoop 2; however, this method not only has troubles in loading and unloading the correction plate. Disadvantages also make the user's active space when operating the X-ray machine 1 small, and the metal hoop 2 and the correction plate 3 increase the weight of the X-ray emitting portion 11, so that the X-ray emitting portion 11 is operating. It is difficult to be rotated during the process and is easy to collide with people or objects.

In the conventional correction method, there is also a method of performing correction using a plane correction plate separated from the X-ray machine 1, but this method usually requires correction by using a plurality of images of the plane correction plate taken by different shooting angles. In order to achieve the purpose of calibration.

Accordingly, it is an object of the present invention to provide an X-ray image correction method based on a movable correction plate.

Therefore, the X-ray machine image correction method based on the movable calibration plate of the present invention is implemented by an X-ray machine and a computing device. The X-ray machine includes an X-ray emitting portion and an X-ray receiving portion, and the calibration plate is adapted to be disposed at a distance from the X-ray device between the X-ray emitting portion and the X-ray receiving portion, and includes a A substrate body that cannot be imaged on an X-ray image and a plurality of correction members that can be imaged on the X-ray image. The substrate body includes a first plate portion and a second plate portion that are coupled to each other and are not parallel to each other, and the correction members respectively correspond to a three-dimensional coordinate and are spaced apart from the first plate portion and the second plate portion. Wherein when the calibration plate is photographed in the first orientation by the X-ray machine to generate a pair of images corresponding to the first orientation, the correction members do not overlap each other in the image. The X-ray image correction method based on the movable calibration plate comprises a step (a), a step (b), and a step (c).

In the step (a), the X-ray machine captures the calibration plate in the first orientation to generate a first image.

The step (b) is that the computing device recognizes image coordinates corresponding to the plurality of correcting members in the first image and the correcting members.

In the step (c), the computing device calculates a plurality of correction parameters according to the three-dimensional coordinates corresponding to the correction components and the image coordinates corresponding to the first image.

The invention has the advantages that the calibration plate of the invention does not need to be fixed on the X-ray machine, and has the advantages of easy installation, lightness, portability, etc., and the invention can achieve the purpose of calibration only by using a single image.

Referring to FIG. 2 and FIG. 3, an embodiment of the X-ray machine image correction method based on the movable calibration plate of the present invention is implemented by an X-ray machine 1 and a computing device (not shown).

The X-ray machine 1 includes an X-ray emitting portion 11 and an X-ray receiving portion 12. The movable correction plate 4 is adapted to be disposed at a distance from the X-ray machine 1 between the X-ray emitting portion 11 and the X-ray receiving portion 12, and includes a substrate body 41 that is not imaged on the X-ray image. And a plurality of correcting members 42 that can be imaged on the X-ray image.

The substrate body 41 has an oblique mountain shape and includes a first plate portion 411 and a second plate portion 412 which are coupled to each other and are not parallel to each other; and when laid flat, the first plate portion 411 and the second plate portion 412 are not parallel to the plumb line.

Referring to FIGS. 4-6, the correcting members 42 are disposed at intervals in the first plate portion 411 and the second plate portion 412, and the plurality of correcting members 42 disposed on the first plate portion 411 are on the first plate. A plurality of rows are formed on the portion 411, and the plurality of correcting members 42 disposed on the second plate portion 412 form a plurality of rows on the second plate portion 412, wherein the setting of the correcting members 42 further satisfies the following characteristics: The correcting member 42 does not overlap each other in the front and rear azimuth image 51 generated by the X-ray machine 1 in the front-back orientation (anteroposterior) as shown in FIG. 2, and the X-ray machine 1 is as shown in the figure. The lateral orientation shown in FIG. 5 does not overlap each other in the side orientation image 52 produced by the correction plate 4.

In addition, the material of the substrate body 41 belongs to the plastic, so that the substrate body 41 cannot be imaged on the X-ray image, such as acrylic or polyetheretherketone (PEEK); and the material of each correcting member 42 belongs to metal or The ceramic allows the correcting member 42 to be imaged on an X-ray image, such as steel beads, aluminum beads, or ceramic beads.

Referring to FIG. 7, an embodiment of the X-ray machine image correction method based on the movable calibration plate of the present invention includes the following steps.

First, at step 61, the three-dimensional world coordinate of each of the correcting members is measured using a coordinate measuring machine.

Next, in step 62, the X-ray machine captures the calibration plate in a first orientation to generate a first image. Here, if the X-ray machine image correction is to be performed on the front and rear orientations, the first orientation is the front-rear orientation and the first image is a front-rear orientation image; and if the X-ray image correction is to be performed for the lateral orientation The first orientation is the lateral orientation and the first image is a lateral orientation image.

Next, in step 63, the computing device uses the existing image recognition technology to identify the image coordinates corresponding to the correcting members and the correcting members in the first image.

Next, in step 64, the computing device uses an existing image correction algorithm, such as Chua's correction, to calculate a plurality of corrections according to the world coordinates corresponding to the correcting members and the corresponding image coordinates in the first image. The parameters, thus completing the image correction of the X-ray machine.

In particular, by the design of the correction plate 4, the first image can simulate at least two combinations of images of the plane correction plate captured from different shooting angles, so the invention can be achieved only by using a single image. Corrective purpose. In addition, in the case where the correction is performed using a single image, the present invention also has higher correction accuracy than the conventional method of performing X-ray machine image correction using the movable plane correction plate. In addition, the present invention does not need to fix the calibration plate 4 to the X-ray machine 1, and has the advantages of easy installation, light weight, and portability.

In addition, it should be particularly noted that the oblique mountain type of the calibration plate 4 of the present invention is designed for both X-ray image correction of the front-rear direction and the lateral orientation, and the purpose is to make the correction member 42 in the front-rear orientation image. 51 does not overlap each other, and does not overlap each other in the lateral orientation image 52. However, if it is required to perform X-ray image correction for a specific shooting orientation, the calibration plate is only designed to satisfy that "the first plate portion and the second plate portion are coupled to each other and are not parallel to each other" and "the The condition that the correction member does not overlap each other in the image captured from the specific imaging direction may be used. For example, if the front and rear orientations are only required to be corrected, the correction plate may have other embodiments, such as the L-type correction plate 9 shown in FIG. 8, and the first plate portion 911 and the second plate portion 912 are coupled to each other. And not parallel to each other; when used for image correction of the front and rear orientation, as shown in FIG. 9, the correction plate 9 is laterally flat, and although the correcting member 92 overlaps in the lateral orientation image, The front and rear azimuth images do not overlap each other.

Referring to Figures 10-12, in another embodiment, the present invention contemplates another movable calibration plate 7. The calibration plate 7 includes a substrate body 71 that is not imageable on the X-ray image and a plurality of correction members 72 that are imageable on the X-ray image. The substrate body 71 is X-shaped and includes a first plate portion 711 and a second plate portion 712 that are coupled to each other and are not parallel to each other; and when laid flat, the first plate portion 711 and the second plate portion 712 None of them are parallel to the plumb line. The first plate portion 711 divides each row of the correcting members of the second plate portion 712 into a first sub-row and a second sub-row, respectively located on opposite sides of the first plate portion 711, and the second plate portion 712 Each row of the correcting members of the first plate portion 711 is also partitioned into a first sub-row and a second sub-row, respectively located on opposite sides of the second plate portion 712. The correcting members 72 also do not overlap each other in the front and rear azimuth images and the lateral azimuth images.

In particular, the number of the correcting members 72 included in the plurality of correcting member rows disposed in the first plate portion 711 is different, so that the first plate portion 711 has two corresponding correcting member rows and is not provided with the correcting member. Empty areas 73, 74 of 72. As shown in FIGS. 10 and 11, the number of the correcting members 72 of the second sub-row 7111 of the second row of the first plate portion 711 and the second sub-row 7111 of the third row is four, and in the first plate portion. The number of the correcting members 72 of the other sub-rows on the 711 is five, so that the second row and the third row of the first plate portion 711 respectively correspond to an empty region 73, 74, wherein the empty region 73 corresponding to the second row is located. One end of the second sub-row 7111 of the second row, and the empty area 74 corresponding to the third row is located between a first correcting member 72a and a second correcting member 72b of the second sub-row 7112 of the third row .

In the conventional X-ray image correction method, it is necessary to manually determine the orientation of the correction plates 4, 7 in the output image of the X-ray machine, and then further define each correction component in the image. The physical correction component corresponding to the calibration plate and its corresponding world coordinates.

For example, FIG. 13 lists four possible output images of the front and rear azimuth images of the correction plate 7 taken by an X-ray machine, wherein FIG. 13(b), FIG. 13(c), and FIG. 13(d) are respectively Fig. 13(a) is rotated 90 degrees, 180 degrees, and 270 degrees in the clockwise direction. Referring to FIG. 10 and FIG. 13 , in the conventional X-ray image correction method, it is necessary to manually determine whether the output image of the X-ray machine belongs to the image output listed in FIG. 13 , that is, the correction plate is determined in the image. The orientation direction of 7 is defined, and the physical correction component corresponding to each correction component in the image and its world coordinates are defined, for example, the correspondence relationship is defined by numbering, for example, the corresponding number of the calibration component numbered N1 in the image is The entity correction piece of N1 and its world coordinates, the correction piece numbered N2 in the image correspond to the entity correction piece numbered N2 and its world coordinates, and the like.

By designing the equal-space regions 73, 74 of the correction plate 7, the present invention can automatically determine the direction in which the correction plate 7 is placed in the image, thereby defining the world corresponding to the image coordinates of each of the correction members 72. coordinate. The method for automatically determining the direction in which the correction plate 7 is placed in the first image by using the same area 73, 74 is as follows: First, before the image correction is performed by using the first image, the first orientation is used Shooting the calibration plate 7 to generate a second image; then, comparing the reference image block and the plurality of different angles in the second image, comparing the reference image block in the first image a most similar target image block, wherein the reference image block includes the equal-space regions 73, 74 in the second image and a plurality of calibrators 72 adjacent to the equal-space regions 73, 74; The rotation angle of the reference image block corresponding to the target image block determines the direction in which the correction plate 7 is placed in the first image.

According to the above example, referring to FIG. 14, if the X-ray machine is to perform image correction of the front and rear orientation, a front and rear azimuth image of the correction plate 7 is captured, that is, the second image 8 is then manually The second image 8 determines the direction in which the correction plate 7 is placed and defines the reference image block 81, and rotates the reference image block 81 and its 90 degrees, 180 degrees, and 270 degrees in the clockwise direction. Searching and comparing in the front and rear azimuth image (first image) to be used for image correction, and comparing the target image block most similar to the reference image block 81, according to the second image The direction of the correction plate 7 and the rotation angle of the reference image block 81 determine that the direction of the correction plate 7 is in the front and rear azimuth image (first image) to be used for image correction. The four of the 13 orientations. In this example, the orientation of the calibration plate 7 in the second image 8 is the same as that of FIG. 13(a). If the reference image block 81 is rotated 90 degrees clockwise, the front and rear orientations of the correction image to be used for image correction are used. When the target image block is searched for in the image (first image), the direction of the correction plate 7 is the same as that of FIG. 13(b) in the front and rear azimuth image (first image) to be used for image correction.

In particular, the above-mentioned manually determining the direction in which the correction plate 7 is placed in the second image 8 and defining the reference image block 81 need only be performed once, and then it is necessary to determine the correction plate in a front and rear azimuth image. When the direction of 7 is placed, the above method can be used to automatically judge. Further, although the number of the equal-space areas 73, 74 on the correction plate 7 is two in this embodiment, it may not be limited thereto, and the number may be one or more in other embodiments.

In summary, the present invention is based on the X-ray machine image correction method of the movable calibration plate. By the design of the correction plates 4 and 7, the calibration plates 4 and 7 do not have to be fixed on the X-ray machine, and the operation is easy. The advantages of installation, lightness, portability, etc., and the image of the calibration plate 4, 7 can simulate the combination of at least two images of the plane correction plate captured from different shooting angles, so that the present invention only needs to utilize a single image. That is, the calibration purpose can be achieved, and by the design of the equal-space regions 73, 74 of the calibration plate 7, the orientation of the correction plate 7 in the image can be automatically determined, thereby defining the image coordinates of each correction member. The corresponding world coordinates, and the calibration parameters of the X-ray machine are estimated, so that the object of the present invention can be achieved.

However, the above is only the embodiment of the present invention, and the scope of the invention is not limited thereto, and all the simple equivalent changes and modifications according to the scope of the patent application and the patent specification of the present invention are still Within the scope of the invention patent.

1‧‧‧X-ray machine

11‧‧‧X-ray emission department

12‧‧‧X-ray receiver

2‧‧‧Metal hoop

3‧‧‧ calibration board

4‧‧‧ calibration board

41‧‧‧Substrate body

411‧‧‧First Board

412‧‧‧ Second Board

42‧‧‧calibration

51‧‧‧ front and rear azimuth images

52‧‧‧ Lateral azimuth image

61~64‧‧‧Steps

7‧‧‧ calibration board

71‧‧‧Substrate body

711‧‧‧First Board

7111‧‧‧Second sub-row

7112‧‧‧Second sub-row

712‧‧‧ Second Board

72‧‧‧calibration

72a‧‧‧First Corrector

72b‧‧‧Second Correction

73‧‧‧empty area

74‧‧‧ empty area

N1~N3‧‧‧ number

8‧‧‧Second image

81‧‧‧Reference image block

9‧‧‧ calibration board

911‧‧‧First Board

912‧‧‧ Second Board

92‧‧‧calibration

Other features and advantages of the present invention will be apparent from the embodiments of the present invention, wherein: FIG. 1 is a perspective view illustrating a conventional use of a calibration plate attached to an X-ray emitting portion of an X-ray machine. FIG. 2 is a perspective view showing a first embodiment of a movable calibration plate for correcting X-ray image of front and rear orientation; FIG. 3 is a perspective view illustrating the calibration plate. FIG. 4 is an X-ray image illustrating the front and rear azimuth images of the first embodiment of the calibration plate; FIG. 5 is a perspective view illustrating the first embodiment of the calibration plate. Performing a lateral orientation of the X-ray machine image correction; FIG. 6 is an X-ray image illustrating the lateral orientation image of the first embodiment of the calibration plate; FIG. 7 is a flow chart illustrating the present invention based on the motion correction FIG. 8 is a perspective view showing a second embodiment of the calibration plate; FIG. 9 is a perspective view showing the second embodiment of the calibration plate. Before coming FIG. 10 is a perspective view showing a third embodiment of the calibration plate; FIG. 11 is a plan view showing the third embodiment of the calibration plate in conjunction with FIG. 10; Is a side view, the third embodiment of the calibration plate is described with reference to FIGS. 10 and 11; FIGS. 13(a) to (d) are both X-ray images, illustrating the third of the calibration plate being photographed by an X-ray machine. Four possible image outputs of the front and rear azimuth images of the embodiment; and FIG. 14 is an X-ray image, which indicates that a reference image is determined on a front and rear azimuth image of the third embodiment of the calibration plate that is pre-photographed. Block.

Claims (8)

An X-ray machine image correction method based on a movable calibration plate is implemented by an X-ray machine and a computing device, the X-ray machine comprising an X-ray emitting portion and an X-ray receiving portion, the calibration plate being adapted to be X The optical machine is disposed at a distance between the X-ray emitting portion and the X-ray receiving portion, and includes a substrate body that cannot be imaged on the X-ray image and a plurality of correcting members that can be imaged on the X-ray image. The substrate body includes a first plate portion and a second plate portion that are coupled to each other and are not parallel to each other, and the correction members respectively correspond to a three-dimensional coordinate and are disposed at intervals in the first plate portion and the second plate portion, wherein When the correcting plate is photographed by the X-ray machine in a first orientation to generate a pair of images corresponding to the first orientation, the correcting members do not overlap each other in the image, and the X-ray machine based on the movable calibration plate The image correction method comprises the following steps: (a) the X-ray machine captures the calibration plate in the first orientation to generate a first image; (b) the computing device recognizes the plurality of correction components in the first image and Image coordinates corresponding to the correcting parts; and (c) the meter The calculating device calculates a plurality of correction parameters according to the three-dimensional coordinates corresponding to the correcting members and the image coordinates corresponding to the first image. The method for correcting an X-ray image based on the movable calibration plate according to claim 1, wherein when the device is placed flat, the first plate portion and the second plate portion are not parallel to the vertical line, wherein in the step (a) The first orientation is one of a front-rear orientation and a lateral orientation. The movable correction plate-based X-ray image correction method according to claim 1, wherein the plurality of correction members disposed on the first plate portion form a plurality of rows on the first plate portion, and are disposed in the first A plurality of correcting members of the second plate portion form a plurality of rows on the second plate portion. The movable correction plate-based X-ray machine image correction method according to claim 3, wherein the plurality of correction member rows disposed in the first plate portion have different numbers of correction members, such that the first plate portion There is at least one pair of empty areas that should be aligned with the correcting member and not provided with the correcting member. The method for correcting the X-ray image based on the movable calibration plate according to claim 4, further comprising the following steps performed before the step (c): (d) the X-ray machine photographs the calibration plate in the first orientation And generating a second image; (e) the computing device compares a reference image block in the second image and at least one rotation thereof, and compares a target similar to the reference image block in the first image An image block, wherein the reference image block includes the at least one empty area in the second image and a plurality of correction elements adjacent to the at least one empty area; and (f) the computing device corresponds to the target image block The rotation of the reference image block determines the direction in which the calibration plate is placed, and determines the three-dimensional coordinate corresponding to the plurality of correction components of the calibration plate and the image corresponding to the first image according to the direction in which the calibration plate is placed. The correspondence between the coordinates. The movable correction plate-based X-ray machine image correction method according to claim 3, wherein the substrate body is X-shaped, and the first plate portion separates each row of the correction members of the second plate portion into respectively a first sub-row and a second sub-row on both sides of the first plate portion. The movable calibration plate-based X-ray machine image correction method according to claim 3, wherein the substrate body is in an oblique mountain shape. The X-ray image correction method based on the movable calibration plate according to claim 1, wherein the material of the substrate body belongs to a plastic, and the material of each correction component belongs to one of metal and ceramic.