System and method for calibrating geometric magnification times of X-ray equipment

Abstract

The invention relates to the technical field of X-ray detection equipment, in particular to a calibration system and method for the geometric magnification of X-ray equipment. During use, a calibration die body is loaded on an objective table; adjusting the ray source, the detector and the objective table, so that the focus of the X-ray source passes through the small hole and the small hole is imaged into a circle; carrying out primary projection imaging on the calibration die body, and respectively measuring the projection lengths of the first imaging vertical plate and the second imaging vertical plate on the detector; and calculating SOD, SDD and a geometric magnification M according to a formula. Through the cooperation of a double-imaging vertical plate structure provided by the calibration die body, the X-ray source and the detector, SOD, SDD and geometric magnification M can be solved only through one-time projection imaging, and the calibration die body or an objective table does not need to be moved in the X-ray direction. The problem that in the prior art, X-ray equipment without an objective table X-axis movement function cannot complete geometric magnification factor calibration is solved, and the calibration efficiency and precision are improved.

Description

Technical Field

[0001] This invention relates to the field of X-ray inspection equipment technology, and in particular to a calibration system and method for the geometric magnification of X-ray equipment. Background Technology

[0002] In X-ray equipment, to measure feature dimensions in a projected image, the geometric magnification ratio M must first be accurately calculated. M is the ratio of SDD (distance from the X-ray source to the detector) to SOD (distance from the X-ray source to the center of rotation).

[0003] The usual practice is to use a calibration phantom to calculate the result through two imaging operations. The calibration phantom needs to be moved a certain distance Δs in the X-ray direction, and the system accurately acquires this movement data.

[0004] However, many X-ray devices lack a stage with X-axis motion (along the X-ray direction), making it impossible to move the phantom. Summary of the Invention

[0005] The purpose of this invention is to provide a calibration system and method for the geometric magnification of X-ray equipment, aiming to solve the problem in the prior art that the calibration phantom must be moved to calculate the geometric magnification.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a calibration system for the geometric magnification of an X-ray device, comprising a calibration phantom, an X-ray source, and a detector; The calibration phantom includes a first imaging vertical plate and a second imaging vertical plate, which are arranged in parallel to form a measurable projected image after X-rays pass through. The X-ray source is used to emit X-rays that penetrate the calibration phantom; The detector is used to receive X-rays that have penetrated the calibration phantom and form a projection image.

[0007] Both the first imaging vertical plate and the second imaging vertical plate are provided with through circular holes.

[0008] The circular holes on the first and second imaging vertical plates have the same diameter, which is less than φ1mm.

[0009] The thickness of the first imaging vertical plate and the second imaging vertical plate is 5mm ± 2mm.

[0010] The projection length of the second imaging vertical plate is designed to be 1 / 2 to 2 / 3 of the field of view of the detector. The actual distance between the first imaging vertical plate and the second imaging vertical plate ensures that the projections of the first imaging vertical plate and the second imaging vertical plate on the detector do not overlap and are clearly distinguishable.

[0011] In a second aspect, a calibration method for the geometric magnification of an X-ray device, used in the calibration system for the geometric magnification of an X-ray device described in the first aspect, includes the following steps: The calibration phantom is mounted on the stage; Adjust the X-ray source, detector, and stage so that the focal point of the X-ray source passes through the pinhole and the pinhole image is circular; Perform a projection imaging of the calibration phantom and measure the projection lengths of the first and second imaging vertical plates on the detector, respectively. Calculate SOD, SDD, and geometric magnification M using the formula.

[0012] This invention discloses a calibration system for the geometric magnification of X-ray equipment. In use, a calibration phantom is mounted on a stage; the X-ray source, detector, and stage are adjusted so that the X-ray source focal point passes through a pinhole and the pinhole image is circular; a single projection image is performed on the calibration phantom, and the projected lengths of the first and second imaging vertical plates on the detector are measured; the SOD, SDD, and geometric magnification M are calculated according to formulas. Through the dual imaging vertical plate structure provided by the calibration phantom and the cooperation between the X-ray source and detector, SOD, SDD, and geometric magnification M can be calculated with only a single projection image, without the need to move the calibration phantom or stage along the X-ray direction. This solves the problem in existing technologies where X-ray equipment without stage X-axis movement cannot complete geometric magnification calibration, thus improving calibration efficiency and accuracy. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a calibration system for the geometric magnification of X-ray equipment provided by the present invention.

[0015] Figure 2 yes Figure 1 A magnified view of detail A.

[0016] Figure 3 This is a side view of the calibration phantom.

[0017] Figure 4 This is the front view of the calibration phantom.

[0018] Figure 5 This is a flowchart of a calibration method for the geometric magnification of X-ray equipment provided by the present invention.

[0019] In the figure: 1-calibration phantom, 2-X-ray source, 3-detector, 11-first imaging vertical plate, 12-second imaging vertical plate, 13-circular hole. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] Please see Figures 1 to 4 In a first aspect, the present invention provides a calibration system for the geometric magnification of an X-ray device, comprising a calibration phantom 1, an X-ray source 2, and a detector 3; The calibration phantom 1 includes a first imaging vertical plate 11 and a second imaging vertical plate 12, which are arranged in parallel to form a measurable projection image after X-rays pass through. The X-ray source 2 is used to emit X-rays that penetrate the calibration phantom 1; The detector 3 is used to receive X-rays after they penetrate the calibration phantom 1 and form a projection image.

[0022] Both the first imaging vertical plate 11 and the second imaging vertical plate 12 are provided with through circular holes 13.

[0023] The circular holes 13 on the first imaging vertical plate 11 and the second imaging vertical plate 12 have the same diameter, and the diameter is less than φ1mm.

[0024] The thickness of the first imaging vertical plate 11 and the second imaging vertical plate 12 is 5mm ± 2mm.

[0025] The projection length of the second imaging vertical plate is designed to be 1 / 2 to 2 / 3 of the field of view of the detector 3. The actual distance between the first imaging vertical plate 11 and the second imaging vertical plate 12 ensures that the projections of the first imaging vertical plate 11 and the second imaging vertical plate 12 on the detector 3 do not overlap and are clearly distinguishable.

[0026] In this embodiment, the first and second imaging vertical plates are made of high-density materials, resulting in high imaging contrast. Steel, copper, and lead are selected, but stainless steel is preferred due to its rust-free properties and cost-effectiveness. The calibration phantom 1 is fixedly mounted on the stage of the X-ray equipment. The first imaging vertical plate 11 is precisely aligned with the rotation center point (O point) of the equipment, and the second imaging vertical plate 12 is parallel to the first imaging vertical plate 11 at a preset distance Δs. The actual widths L1 and L2 of the two imaging vertical plates and the actual distance Δs between them are pre-measured using a high-precision metrology device. The projected length of the second imaging vertical plate 12 is designed to occupy more than 1 / 2 and less than 2 / 3 of the field of view of the detector 3. The value of Δs must ensure that the projections of the first and second imaging vertical plates 11 do not overlap on the detector 3 and are clearly distinguishable.

[0027] By adjusting the relative position of the X-ray source and detector 3 and rotating the stage angle, the focal point of X-ray source 2 is aligned with the circular hole 13 on the first imaging vertical plate 11. The projected image of detector 3 is observed. When the hole image appears as a standard circle, it indicates that the X-ray source is perpendicular to the imaging plate. At this time, X-ray source 2 is activated to emit X-rays. The X-rays penetrate the stainless steel imaging vertical plate (thickness 5mm, diameter of circular hole 13 less than φ1mm) and are received by detector 3 to form an image containing the projections of the two imaging vertical plates. The grid line measuring tool on detector 3 is used to measure the number of grid lines occupied by the projection of the first imaging vertical plate 11 to obtain L1′, and to measure the number of grid lines occupied by the projection of the second imaging vertical plate 12 to obtain L2′. Combined with the pre-determined parameters L1, L2, and Δs, SOD, SDD, and geometric magnification M are calculated using the formulas SOD / SDD=L1 / L1′ and (SOD+Δs) / SDD=L2 / L2′. Please see Figure 5 Secondly, a calibration method for the geometric magnification of an X-ray device, used in the calibration system for the geometric magnification of an X-ray device described in the first aspect, includes the following steps: S1 loads calibration phantom 1 onto the stage; Specifically, the calibration phantom 1 is fixedly installed on the stage of the X-ray equipment, and it is necessary to ensure that the first imaging vertical plate 11 is precisely aligned with the rotation center point of the equipment (point O, that is, the side of the first imaging vertical plate 11 away from the second imaging vertical plate 12 passes through the center).

[0028] S2 adjusts the X-ray source, detector 3, and stage so that the focal point of X-ray source 2 passes through the pinhole and the pinhole image is circular; Specifically, by raising and lowering the relative position of the X-ray source and detector 3 and rotating the stage, the image of the circular hole 13 in the projection is observed. When the image of the small hole appears as a standard circle, it indicates that the focal point of the X-ray source is aligned with the small hole of the calibration phantom 1. At this time, the X-ray source is perpendicular to the imaging plate, ensuring the accuracy of the projection geometry.

[0029] S3 performs a projection imaging of the calibration phantom 1 and measures the projection lengths of the first imaging vertical plate 11 and the second imaging vertical plate 12 on the detector 3 respectively. Specifically, the X-ray source is activated to perform a single projection imaging on the calibration phantom 1, forming an image on the detector 3 that includes the projections of two imaging vertical plates. Using the grid lines set on the detector 3 as the measurement reference, the number of grid lines occupied by the projection of the first imaging vertical plate 11 is measured using a measuring tool to obtain L1′, and the number of grid lines occupied by the projection of the second imaging vertical plate 12 is measured to obtain L2′.

[0030] S4 calculates SOD, SDD, and geometric magnification M according to the formula.

[0031] Specifically, the pre-determined actual widths L1 and L2 of the two imaging vertical plates and the actual distance Δs, along with the projection lengths L1′ and L2′ measured in step S3, are substituted into the following formula: SOD / SDD=L1 / L1′ (SOD+Δs) / SDD=L2 / L2′ SOD and SDD can be calculated, and then the geometric magnification factor M can be obtained. The above-disclosed embodiments are merely preferred embodiments of a calibration system and method for the geometric magnification of X-ray equipment according to the present invention. They should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A calibration system for the geometric magnification of X-ray equipment, characterized in that, This includes a calibration phantom, an X-ray source, and a detector; The calibration phantom includes a first imaging vertical plate and a second imaging vertical plate, which are arranged in parallel to form a measurable projected image after X-rays pass through. The X-ray source is used to emit X-rays that penetrate the calibration phantom; The detector is used to receive X-rays that have penetrated the calibration phantom and form a projection image.

2. The calibration system for the geometric magnification of X-ray equipment as described in claim 1, characterized in that, Both the first imaging vertical plate and the second imaging vertical plate are provided with through circular holes.

3. The calibration system for the geometric magnification of X-ray equipment as described in claim 2, characterized in that, The circular holes on the first imaging vertical plate and the second imaging vertical plate have the same diameter, and the diameter is less than φ1mm.

4. The calibration system for the geometric magnification of X-ray equipment as described in claim 1, characterized in that, The thickness of the first imaging vertical plate and the second imaging vertical plate is 5mm ± 2mm.

5. The calibration system for the geometric magnification of X-ray equipment as described in claim 1, characterized in that, The projection length of the second imaging vertical plate is designed to be 1 / 2 to 2 / 3 of the field of view of the detector. The actual distance between the first imaging vertical plate and the second imaging vertical plate ensures that the projections of the first imaging vertical plate and the second imaging vertical plate on the detector do not overlap and are clearly distinguishable.

6. A method for calibrating the geometric magnification of an X-ray device, used in the calibration system for the geometric magnification of an X-ray device as described in any one of claims 1-5, characterized in that, Includes the following steps: The calibration phantom is mounted on the stage; Adjust the X-ray source, detector, and stage so that the focal point of the X-ray source passes through the pinhole and the pinhole image is circular; Perform a projection imaging of the calibration phantom and measure the projection lengths of the first and second imaging vertical plates on the detector, respectively. Calculate SOD, SDD, and geometric magnification M using the formula.

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