Flat panel detector positioning collimation method and device and digital X-ray photography system

Abstract

The invention relates to the field of digital X-ray photography, and provides a flat panel detector positioning collimation method which comprises the following steps: acquiring attitude information D (alpha, beta, gamma) of a flat panel detector carrier through an attitude sensor arranged in the flat panel detector carrier, and feeding back the attitude information D (alpha, beta, gamma) to a beam limiting device collimation unit; the method comprises the following steps: when a beam limiting device provided with a collimation unit is positioned above a measured object and a light field is opened, acquiring attitude information S (alpha, beta, gamma) of the beam limiting device through the collimation unit of the beam limiting device; according to the attitude information D (alpha, beta, gamma) of the flat panel detector carrier and the attitude information S (alpha, beta, gamma) of the beam limiting device, an operator is guided to adjust the attitude of the beam limiting device until S (alpha, beta, gamma) = D (alpha, beta, gamma), so that the light field of the beam limiting device is perpendicular to the plane of the flat panel detector carrier; the beam limiting device collimation unit sends a ranging signal to the flat panel detector carrier; and dynamically selecting and executing a corresponding target position calculation and beam limiting device position adjustment strategy based on the effective and visible distance measuring sensor in the sensor set and the received distance measuring signal, so that the position of the beam limiting device approaches to a set target point So.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of digital X-ray photography, in particular to a flat panel detector positioning and collimation method, device and digital X-ray photography system. BACKGROUND

[0002] Digital X-ray photography (DR) system is widely used in modern medical diagnosis, and its imaging quality highly depends on the accurate collimation of X-ray radiation field and flat panel detector. Conventional DR equipment fixes the flat panel detector through the gantry to ensure the vertical alignment of the radiation field and the detector plane, thereby obtaining the image range and clarity meeting the diagnostic requirements. However, in special position photography such as wheelchair position and stretcher position, and in the application of mobile DR equipment, the flat panel detector needs to be placed directly behind the patient, resulting in the loss of the fixed spatial position relationship between the flat panel detector and the X-ray source.

[0003] Current collimation schemes for mobile detectors mainly rely on two ways, namely manual visual adjustment and static sensor assisted positioning. The former mainly relies on the operator to manually align the light field and the detector mark by observation, and the latter mainly uses a fixed number of positioning sensors (such as infrared or electromagnetic sensors) to assist positioning. However, the above prior art cannot dynamically adapt the number of visible sensors when the detector is blocked, and cannot simultaneously fuse the posture calibration and spatial positioning, resulting in a high failure rate of special position photography. SUMMARY

[0004] The present application provides a flat panel detector positioning and collimation method, device and storage medium, which realizes reliable collimation in complex occlusion environment through dynamic posture calibration and occlusion adaptive positioning, and avoids repeated retakes in DR scenarios.

[0005] In one aspect, the present application provides a flat panel detector positioning and collimation method, which comprises:

[0006] acquiring the posture information D(α,β,γ) of the flat panel detector carrier through the posture sensor built in the flat panel detector carrier and feeding back to the collimator collimation unit;

[0007] acquiring the posture information S(α,β,γ) of the collimator through the collimator collimation unit when the collimator equipped with the collimation unit is located above the measured object and the light field is opened;

[0008] guiding the operator to adjust the posture of the collimator until S(α,β,γ)=D(α,β,γ) according to the posture information D(α,β,γ) of the flat panel detector carrier and the posture information S(α,β,γ) of the collimator, so that the collimator light field is perpendicular to the flat panel detector carrier plane;

[0009] sending a ranging signal from the collimator collimation unit to the flat panel detector carrier;

[0010] monitoring the blocking state of the ranging sensors around the flat panel detector carrier in real time to obtain a current effective visible sensor set;

[0011] based on the effective visible ranging sensors in the sensor set and the ranging signals, dynamically selecting and executing a corresponding target position calculation and limiter position adjustment strategy to make the position of the limiter approach the set target point So.

[0012] When the position of the limiter has approached the target point So, collimation is completed.

[0013] In another aspect, the present application provides a digital X-ray photography system, comprising a flat panel detector carrier, a limiter and a central processing unit.

[0014] The flat panel detector carrier is placed on the back of the measured object and integrates a first attitude sensor and a plurality of ranging sensors arranged around the flat panel detector carrier.

[0015] The limiter comprises a second attitude sensor, a ranging signal transmitter and a light field projection module.

[0016] The central processing unit is configured to: after determining the part to be photographed, the light field projection module covers the part to be photographed, and compares the attitude data D(α,β,γ) and S(α,β,γ) output by the first attitude sensor and the second attitude sensor; when S(α,β,γ)=D(α,β,γ); monitoring the blocking state of the ranging sensors around the flat panel detector carrier in real time to obtain a current effective visible sensor set; based on the effective visible ranging sensors in the sensor set and the distance measurement value obtained based on the ranging sensors and the ranging signal transmitter, dynamically selecting and executing a corresponding target position calculation and limiter position adjustment strategy to make the position of the limiter approach the set target point So.

[0017] In a third aspect, the present application provides an electronic device, which comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor executes the computer program to realize the steps of the technical solution of the flat panel detector positioning and collimation method as described above.

[0018] In a fourth aspect, the present application provides a storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the technical solution of the flat panel detector positioning and collimation method as described above.

[0019] From the above technical solutions provided by the present application, on the one hand, by comparing the posture information (D(a, b, g) and S(a, b, g)) of the flat panel detector carrier and the beam limiter in real time, the posture adjustment instruction is generated until they are consistent, and it is ensured that the X-ray radiation field is always perpendicular to the detector plane, thereby avoiding image geometric distortion caused by inclined incidence of rays from the root; on the other hand, by dynamically monitoring the number of effective visible ranging sensors, and adaptively selecting the positioning strategy based on the number of effective visible ranging sensors, reliable positioning in any occlusion scene is realized, and the industry problem of being unable to position when the flat panel detector is completely occluded is solved; thirdly, after the calibrated posture, i.e., S(a, b, g) = D(a, b, g), the dynamic positioning strategy based on the number of effective visible ranging sensors is formulated, the posture calibration and dynamic positioning are integrated into a unified process, the “posture-position” integrated adjustment is realized, the operation steps are reduced, and the preparation time of wheelchair position / stretcher position and the like scenes is shortened. In summary, the technical solutions of the present application realize reliable collimation in a complex occlusion environment through dynamic posture calibration and occlusion adaptive positioning, and avoid repeated re-shooting in a DR scene. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0021] Figure 1 is a flowchart of the flat panel detector positioning and collimation method provided by the embodiments of the present application;

[0022] Figure 2 is a schematic diagram of a rectangular region surrounded by four ranging sensors around the flat panel detector carrier provided by the present application;

[0023] Figure 3 is a schematic diagram of the projection of the light field formed by the beam limiter and the four ranging sensors around the flat panel detector carrier on the surface of the flat panel detector carrier provided by the present application;

[0024] Figure 4 is a schematic diagram of the beam limiter located above the flat panel detector carrier and the projection located at the center of the flat panel detector carrier provided by the present application;

[0025] Figure 5 is a schematic diagram of the position of the beam limiter approaching the target point So when the flat panel detector carrier exposes three ranging sensors provided by the present application;

[0026] Figure 6Fig. 6 is a schematic diagram of the position approximation of the target point So by the flat panel detector carrier exposing the position of the time-of-flight beamers of two ranging sensors located on the same side of the rectangle according to an embodiment of the present application;

[0027] Figure 7 Fig. 7 is a schematic diagram of the position approximation of the target point So by the flat panel detector carrier exposing the position of the time-of-flight beamers of two ranging sensors located on the diagonal of the rectangle according to an embodiment of the present application;

[0028] Figure 8 Fig. 8 is a schematic diagram of the position approximation of the target point So by the flat panel detector carrier exposing the position of the time-of-flight beamers of a single ranging sensor according to an embodiment of the present application;

[0029] Figure 9 Fig. 9 is a schematic diagram of the center of the flat panel detector deviating from the center of the flat panel detector carrier according to an embodiment of the present application;

[0030] Figure 10 Fig. 10 is a structural diagram of a digital X-ray photography system according to an embodiment of the present application;

[0031] Figure 11 Fig. 11 is a structural diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0033] In this specification, adjectives such as first and second can be used merely to differentiate one element or action from another element or action, without necessarily implying any actual such relationship or order. Where the context allows, reference to an element or component or step (etc.) by the indefinite article "a" or "an" does not exclude the existence of, or the possibility of using, more than one of the element, component or step (etc.).

[0034] In this specification, for the purpose of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportions.

[0035] Digital radiography (DR) system is widely used in modern medical diagnosis, and its imaging quality highly depends on the accurate collimation of X-ray field and flat panel detector. Conventional DR equipment installs flat panel detector through a fixed rack to ensure the vertical alignment of the radiation field and the detector plane, thereby obtaining the image range and clarity that meet the diagnostic requirements. However, in special position photography such as wheelchair position and stretcher position, and in the application of mobile DR equipment, the flat panel detector needs to be placed directly behind the patient, resulting in the loss of the fixed spatial position relationship between the detector and the X-ray source. The current collimation scheme for mobile detectors mainly relies on two ways, namely manual visual adjustment and static sensor assisted positioning. The former mainly relies on the operator to manually align the light field and the detector marker by observation, and the latter mainly uses a fixed number of positioning sensors (such as infrared or electromagnetic sensors) to assist positioning. The existing technologies have the following defects: attitude misalignment leading to image distortion, occlusion causing positioning blind area, and lack of quantitative adjustment standard. Among them, attitude misalignment leading to image distortion specifically manifests in that the attitude deviation (pitch / yaw / roll angle) of the collimator and the detector is not corrected in real time, resulting in the inclined incidence of X-rays into the detector plane and the geometric distortion. Occlusion causing positioning blind area specifically manifests in that when the detector is occluded, the sensor signal is lost, and the spatial position mapping relationship cannot be established, forcing the operator to re-shoot. Lack of quantitative adjustment standard specifically manifests in that the position adjustment relies on the operator's experience, and there is a lack of quantitative basis for determining the "collimation completion" state, which is easy to cause the image quality to be substandard due to small deviations. In summary, the existing technologies cannot dynamically adapt the number of visible sensors when the detector is occluded, and cannot simultaneously fuse attitude calibration and spatial positioning, resulting in a high failure rate of special position photography.

[0036] To solve the above problems of the prior art, the present application proposes a flat panel detector positioning and collimation method, the flow chart of which is shown in FIG. 1, mainly including steps S101-S107, which are described in detail as follows: Figure 1

[0037] Step S101: Obtain the attitude information D(α,β,γ) of the flat panel detector carrier through the attitude sensor built in the flat panel detector carrier and feed back to the collimator collimation unit.

[0038] ​In the embodiments of the present application, the flat panel detector carrier is internally provided with a posture sensor and a plurality of distance measuring sensors, wherein the posture sensor can be a device for acquiring posture data such as a gyroscope, an accelerometer or a magnetometer, and the distance measuring sensor can be a device for measuring distance such as an ultrasonic sensor based on ultrasonic signals, a laser radar or a millimeter wave radar; the posture information D(α,β,γ) of the flat panel detector carrier is acquired by the posture sensor internally provided in the flat panel detector carrier, wherein α, β and γ can be the yaw angle, the pitch angle and the roll angle of the flat panel detector carrier, respectively. Similarly to the flat panel detector carrier, the collimation unit of the beam limiter is internally provided with a posture sensor, a distance measuring signal transmitter and a light field projection module, wherein the posture sensor is used to detect the posture information S(α,β,γ) of the beam limiter, and on the other hand, the posture synchronization between the beam limiter and the flat panel detector carrier is realized by interacting with the posture sensor internally provided in the flat panel detector carrier; α, β and γ in the posture information S(α,β,γ) of the beam limiter can be the yaw angle, the pitch angle and the roll angle of the beam limiter, respectively. It should be noted that in the embodiments of the present application, the digital X-ray photography system will calibrate the light field radiation field of the X-ray tube and the beam limiter before being put into use, so that the light field of the beam limiter coincides with the radiation field of the X-ray tube, and thus the spatial information of the beam limiter can be converted into the spatial information of the X-ray source.

[0039] Step S102: When the beam limiter provided with the collimation unit is located above the measured object and the light field is opened, the posture information S(α,β,γ) of the beam limiter is acquired by the collimation unit of the beam limiter.

[0040] As described above, the collimation unit of the beam limiter is internally provided with a light field projection module. After determining the part to be photographed, the light field projection module opens the light field, covers the part to be photographed and makes the center of the light field completely coincide with the center of the flat panel detector carrier; the distribution of the light field on the flat panel detector carrier is rectangular, for example, it can be a square. When the beam limiter provided with the collimation unit is located above the measured object and the light field is opened, the posture information S(α,β,γ) of the beam limiter is acquired by the collimation unit of the beam limiter.

[0041] Step S103: According to the posture information D(α,β,γ) of the flat panel detector carrier and the posture information S(α,β,γ) of the beam limiter, the operator is guided to adjust the posture of the beam limiter until S(α,β,γ)=D(α,β,γ), so that the light field of the beam limiter is perpendicular to the plane of the flat panel detector carrier.

[0042] As described above, the attitude information D(a, b, g) of the flat panel detector carrier and the attitude information S(a, b, g) of the beam limiter can be synchronized by the interaction between the attitude sensor built in the flat panel detector carrier and the attitude sensor built in the beam limiter. Specifically, the beam limiter collimation unit acquires the attitude information D(a, b, g) of the flat panel detector carrier and compares it with the attitude information S(a, b, g) of the beam limiter to calculate the adjustment deviation value Ad(a', b', g') and prompt the operator of the attitude of the beam limiter, so that when S(a, b, g) = D(a, b, g), the spatial position of the beam limiter and the flat panel detector carrier is consistent, that is, the light field of the beam limiter is perpendicular to the flat panel detector carrier.

[0043] Step S104: sending a ranging signal by the beam limiter collimation unit to the flat panel detector carrier.

[0044] The beam limiter collimation unit is built in a ranging signal transmitter, and the flat panel detector carrier is built in a ranging sensor. The beam limiter collimation unit sends a ranging signal to the flat panel detector carrier through the ranging signal transmitter, and the ranging sensor of the flat panel detector carrier receives the ranging signal to calculate the distance between the beam limiter and the ranging sensor of the flat panel detector carrier.

[0045] Step S105: real-time monitoring of the blocking state of the ranging sensors around the flat panel detector carrier to obtain the current effective visible sensor set.

[0046] As described above, the flat panel detector carrier is built in ranging sensors, which are arranged around the periphery and jointly form a rectangular area, as shown in Figure 2 The width direction characteristic size W is the width of the rectangular area, and the length direction characteristic size L is the length of the rectangular area. The lower left corner of the rectangular area is taken as the coordinate origin (0, 0, 0) to establish a spatial rectangular coordinate system, so that the projection coordinate position of the ranging sensor on the X-Y plane of the coordinate system is known: O1(0, 0, 0), O2(0, W, 0), O3(L, W, 0), and O4(L, 0, 0). As shown in Figure 2 The four ranging sensors forming a rectangular area form a sensor set. For convenience of description, O1, O2, O3, and O4 can be used to represent the four ranging sensors hereinafter.

[0047] Step S106: based on the effective visible ranging sensors in the sensor set and the received ranging signal, dynamically selecting and executing the corresponding target position calculation and beam limiter position adjustment strategy to make the position of the beam limiter approach the set target point So.

[0048] As mentioned before, there are four ranging sensors in the sensor set, however, it is always possible that one or several ranging sensors are blocked in the DR scenario. Once the ranging sensors are blocked, it results in low imaging rate or poor quality for many existing technical solutions, which is an industry problem. In this application, based on the effective visible ranging sensors in the sensor set and the received ranging signals, the corresponding target position calculation and beam limiter position adjustment strategies are dynamically selected and executed, so that the position of the beam limiter approaches the set target point So. If the ranging signal transmitter position of the beam limiter is defined as point S(x, y, z), and the point S(x, y, z) and the four ranging sensors O1, O2, O3 and O4 deployed around the flat panel detector carrier form the light field projection on the flat panel detector surface, as shown in Figure 3 , that is, Figure 3 The vertex of the tetrahedron represents the ranging signal transmitter of the beam limiter, and the four vertices of the tetrahedron bottom represent the four ranging sensors. In the DR scenario, different parts generally need to be photographed at a specified SID (Source Image Distance), so that the imaging quality can be ensured while the patient receives as little radiation as possible. After the part is selected, the SID is generally set to the recommended or empirical value, which is a known item. As known before, through the pose adjustment, the beam limiter is perpendicular to the flat panel detector. At this time, when the projection of the point S is on the center of the flat panel detector, the collimation is best, and the imaging effect is best, that is, when the coordinates (x, y, z) of the point S are the coordinates (x = W / 2, y = L / 2, z = SID) of the target point So, it is the most ideal state, as shown in Figure 4 This means that, Figure 3 The vertex of the example tetrahedron is the point S, which is an ideal state. In the actual DR scenario, the position of the point S, i.e. the beam limiter, can be Figure 3 any position in the space of the example tetrahedron, which also reflects the demand of the flat panel detector positioning and collimation of this application.

[0049] Further, on one hand, if a fixed number of ranging sensors are used, for example, only four ranging sensors are supported for complete solution, if the ranging sensors are blocked by clothes or human body (common in wheelchair position), the system is completely disabled, forcing the operator to switch to manual mode, and the positioning accuracy is lost; on the other hand, if the same mathematical model is used to process all ranging sensors unblocked, when only one or two ranging sensors are blocked or unblocked, the solution diverges due to underdetermined equations, and the generated spatial coordinates are significantly deviated from the actual position. Therefore, in order to solve the contradiction between the dynamic change of the number of available ranging sensors (N value is uncertain) caused by blocking and the minimum constraint condition required by the positioning algorithm, as an embodiment of the present application, based on the effective visible ranging sensors in the sensor set and the received ranging signals, the corresponding target position calculation and position adjustment strategy of the limiter are dynamically selected and executed, so that the position of the limiter approximates the set target point So, which can be: based on the known position coordinates of at least three non-collinear effective visible ranging sensors in the sensor set and the measured distance values to the limiter, a spatial distance equation set is constructed, the current spatial coordinates S(x, y, z) of the limiter are solved by using the Euclidean distance formula, and the position adjustment parameters ΔS(x', y', z') are obtained by comparing the spatial coordinates S(x, y, z) with the coordinates of the target point So, so that the position of the limiter approximates the set target point So; or, based on the position relationship of two effective visible ranging sensors in the sensor set and the measured distance values to the limiter, a specific axial adjustment program is executed, guiding the operator to adjust the projection of the limiter to a specific point on the straight line formed by the two effective visible ranging sensors, so that the position of the limiter approximates the set target point So; or, based on the position of a single effective visible ranging sensor in the sensor set and the measured distance value to the limiter, a single-point guidance adjustment program is executed, guiding the operator to adjust the limiter to the target projection position along the X-axis and Y-axis directions in turn and to the target SID along the Z-axis, so that the position of the limiter approximates the set target point So.

[0050] If the spherical distance equation is simplified as a linear relationship, the position calculation of the edge region will be distorted when the height of the beam limiter changes, which cannot meet the accuracy requirements of central projection. Therefore, in order to solve the contradiction between the existence of ranging signal environmental noise and the positioning accuracy requirements, the known position coordinates of at least three non-collinear effective visible ranging sensors in the sensor set and their measured distance values to the beam limiter are used to construct a spatial distance equation set, and the current spatial coordinates S(x, y, z) of the beam limiter are solved by using the Euclidean distance formula, and the position adjustment parameters ΔS(x', y', z') are obtained by comparing the spatial coordinates S(x, y, z) with the coordinates of the target point So, so that the position of the beam limiter approximates to the set target point So. This can be realized by steps Sa1061 to Sa1064, which are described in detail as follows:

[0051] Step Sa1061: Obtain the measured distance value SDi of point S(x, y, z) to each effective visible ranging sensor Oi.

[0052] The so-called effective visibility of the ranging sensor means that the ranging sensor is not blocked. As described above, point S(x, y, z) represents the actual position of the beam limiter, and the ranging signal transmitter is built-in in the collimation unit of the beam limiter. By interacting with the ranging sensors arranged around the flat panel detector carrier, the measured distance value SDi of S(x, y, z) to each effective visible ranging sensor Oi can be obtained, for example, the measured distance values of the beam limiter to the first, second, third and fourth ranging sensors exposed by the flat panel detector carrier are SD1, SD2, SD3 and SD4 respectively.

[0053] Step Sa1062: According to the position coordinates Oi(xi, yi, 0) of the ranging sensor Oi in the pre-established coordinate system and the Euclidean distance formula A spatial distance equation set containing N equations is constructed.

[0054] The Euclidean distance equation set is an effective and accurate physical model for describing spherical wave propagation, and directly solving the nonlinear equation set can avoid approximation errors and ensure the physical consistency of the spatial coordinates. Assuming that the first, second and third ranging sensors exposed by the flat panel detector carrier are taken as an example, the measured distance values of the beam limiter to the first, second and third ranging sensors exposed by the flat panel detector carrier are SD1, SD2 and SD3 respectively, and the spatial distance equation set containing 3 equations is as follows:

[0055]

[0056] Step Sa1063: Solve the system of equations to obtain the current precise spatial coordinates (x, y, z) of the constrictor.

[0057] By solving the above system of equations 1, the precise spatial coordinates (x, y, z) of the limiter can be obtained.

[0058] Step Sa1064: Calculate the coordinate component differences between point S(x, y, z) and target point So(W / 2, L / 2, SID) to obtain the position adjustment parameter ΔS(x', y', z') = So – S. When ΔS(x', y', z') approaches 0, the position of the clamping device approaches the set target point So. Figure 5 As shown, the vertex of the solid-line quadrangular pyramid represents the target point So, and the vertex of the dashed-line quadrangular pyramid represents the position of the constraint, i.e., point S. When ΔS(x',y',z') approaches 0, the position of the constraint approaches the set target point So, i.e., point S coincides with the target point So.

[0059] As can be seen from steps Sa1061 to Sa1064 of the above embodiments, the influence of ranging noise is suppressed by strict spatial geometric relationships, thereby improving the stability and accuracy of multi-sensor positioning.

[0060] When two effective visible ranging sensors in the sensor set are located on the same sideline of a rectangular area, that is, when two effective visible ranging sensors in the sensor set constitute... Figure 2 If existing collimation schemes are used for the two endpoints of one side of the rectangle, such as the free search mode, which only prompts the operator to "move in the direction of decreasing distance," there is a lack of directional guidance, making it easy to get trapped in local optima (e.g., mistakenly stopping on a non-target projection line), prolonging adjustment time and resulting in a low success rate. Alternatively, the virtual projection assumption scheme, which assumes the limiter height z = 0, leads to a systematic offset between the calculated position and the actual position, failing to meet the vertical projection requirements. To resolve the contradiction between the insufficient geometric constraints of two-point positioning (i.e., only one spatial straight line can be determined) and the need for three-dimensional position solving, when two effective visible ranging sensors in the sensor set are located on the same side of the rectangular area, the above embodiment, based on the positional relationship of the two effective visible ranging sensors in the sensor set and their measured distance values ​​to the limiter, executes a specific axial adjustment procedure to guide the operator to adjust the projection of the limiter to a specific point on the straight line formed by the two effective visible ranging sensors, so that the position of the limiter approaches the set target point. Specifically, this can be achieved through step S. b 1061 to step S b The 1065 implementation is detailed below:

[0061] Step S b 1061: Maintain the stability of the beam limiter attitude.

[0062] Maintaining the collimator posture stable means that the data S(a, b, g) remains stable.

[0063] Step S b 1062: Guide the operator to move the collimator in the direction perpendicular to the edge line of the rectangular region formed by the two effective visible ranging sensors, and monitor the distance values SD1 and SD2 of the collimator to the two effective visible ranging sensors in real time.

[0064] Here, taking the example that the first and second effective visible ranging sensors in the sensor set are located on the same edge line of the rectangular region (the same principle applies when the third and fourth ranging sensors opposite to the first and second ranging sensors are located on the same edge line of the rectangular region), the distance value of the collimator to the first effective visible ranging sensor is denoted as SD1, and the distance value of the collimator to the second effective visible ranging sensor is denoted as SD2. These distance values can be obtained through the interaction of the ranging signal emitter built in the collimator collimation unit and the first and second effective visible ranging sensors of the flat panel detector carrier.

[0065] Step S b 1063: Stop moving the collimator when SD1 and SD2 reach the minimum values at the same time. At this time, the point S is projected on the edge line, and the projection point coordinates satisfy the constraint condition y = 0 or x = 0.

[0066] The constraint condition y = 0 or x = 0 is taken as an example that the first and second effective visible ranging sensors in the sensor set are located on the same edge line of the rectangular region. If the adjacent edge of the edge line of the rectangular region is taken as an example, the projection point coordinates satisfy the constraint condition x = 0.

[0067] Step S b 1064: Based on the position coordinates of the two effective visible ranging sensors, the distance values SD1 and SD2, and the constraint condition, an equation group is constructed

[0068]

[0069] Solve the coordinates (x, y, z) of the current point S.

[0070] Taking the example that the first and second effective visible ranging sensors in the sensor set are located on the same edge line of the rectangular region, the position coordinates of the first effective visible ranging sensor are O1(0, 0, 0), and the position coordinates of the second effective visible ranging sensor are O2(0, W, 0). As for the constraint condition, y = 0 can be selected, or x = 0 can be selected.

[0071] Step Sb1065: Calculate the coordinate component difference between the coordinate (x, y, z) of the current point S and the coordinate of the target point S o(W / 2, L / 2, SID), and obtain the position adjustment parameter AS(x', y', z') = So-S. When AS(x', y', z') approaches 0, the position of the beam limiter approaches the set target point So. As shown in Figure 6 When AS(x', y', z') approaches 0, the vertex of the dashed triangle (representing the actual position of point S) and the vertex of the solid triangle (representing the position of the target point So) approach, indicating that the position of the beam limiter approaches the set target point So.

[0072] Another case of two effective visible ranging sensors in the sensor set is that the two effective visible ranging sensors are located on the diagonal line of the rectangular region, that is, the two effective visible ranging sensors in the sensor set constitute Figure 2 two endpoints of a diagonal line of the rectangle. If the existing collimation scheme, for example, the scheme of directly calculating the intersection point, is used, a binary quadratic equation needs to be solved, and there is a double solution ambiguity, or the mechanical guide rod assisted scheme cannot adapt to different size flat panel detectors, and the versatility is poor. Therefore, in order to solve the contradiction between the lack of explicit coordinates of the diagonal projection point and the center positioning requirement, when the two effective visible ranging sensors in the sensor set are located on the diagonal line of the rectangular region, as an embodiment of the present application, based on the positional relationship of the two effective visible ranging sensors in the sensor set and the measured distance values thereof to the beam limiter, a specific axial adjustment procedure is performed to guide the operator to adjust the projection of the beam limiter to a specific point on the straight line constituted by the two effective visible ranging sensors, so that the position of the beam limiter approaches the set target point So. This can be realized by steps Sc1061 to Sc1065, and the details are as follows:

[0073] Step Sc1061: Maintain the stability of the beam limiter posture.

[0074] The same as the foregoing embodiment, maintaining the stability of the beam limiter posture means that the data S(a, b, g) remains stable.

[0075] Step Sc1062: Guide the operator to move the beam limiter in a direction perpendicular to the diagonal line of the rectangular region constituted by the two effective visible ranging sensors, and monitor the distance values SD1 and SD3 of the beam limiter to the two effective visible ranging sensors in real time.

[0076] Here, the first ranging sensor and the third ranging sensor in the set of sensors that are effectively visible are taken as examples of being located at the two endpoints of the diagonal of the rectangular region (the principle of the algorithm is the same when the two ranging sensors opposite the first ranging sensor and the third ranging sensor, i.e., the second ranging sensor and the fourth ranging sensor, are located at the two endpoints of the diagonal of the rectangular region), the distance value of the chopper to the first effectively visible ranging sensor is denoted as SD1, and the distance value of the chopper to the third effectively visible ranging sensor is denoted as SD3. These distance values can be obtained through the interaction of the ranging signal emitter built into the collimating unit of the chopper and the first and third effectively visible ranging sensors of the flat panel detector carrier.

[0077] Step Sc1063: stop moving when SD1 and SD3 simultaneously reach the minimum value, at which time the point S is projected on the diagonal.

[0078] Stop moving when SD1 and SD3 simultaneously reach the minimum value, at which time the point S is projected on the line connecting the first ranging sensor and the third ranging sensor.

[0079] Step Sc1064: guide the operator to move the chopper in a direction parallel to the diagonal according to the relative size of the values of SD1 and SD3.

[0080] Specifically, the values of SD1 and SD3 can be compared in real time. If SD1 > SD3, then the chopper is moved in the direction of O1, i.e., the first ranging sensor; if SD1 < SD3, then the chopper is moved in the direction of O3, i.e., the third ranging sensor.

[0081] Step Sc1065: stop moving when SD1 ≈ SD3, at which time the point S is projected at the center of the diagonal.

[0082] When the point S is projected at the center of the line connecting the first ranging sensor and the third ranging sensor, the coordinates of the point S satisfy x = W / 2 and y = L / 2.

[0083] Step Sc1066: based on the position coordinates of the two effectively visible ranging sensors, the measured distance values

[0084] SD1, SD3, and the projection constraint condition of the point S, i.e., x = W / 2 and y = L / 2, an equation group is constructed.

[0085] L / 2, an equation group is constructed.

[0086]

[0087] Solve the coordinates of the current point S (x = W / 2, y = L / 2, z).

[0088] Step Sc1067: Calculate the coordinate component difference between the current point S (x=W / 2, y=L / 2, z) and the target point So (W / 2, L / 2, SID), and obtain the position adjustment parameter AS(x', y', z') = So.z-z = SID-z. When AS(x', y', z') approaches 0, the position of the beam limiter approaches the set target point So. As shown in FIG. 11B, when AS(x', y', z') approaches 0, the vertex of the dashed triangle (representing the actual position of point S) approaches the vertex of the solid triangle (representing the position of the target point So), indicating that the position of the beam limiter approaches the set target point So. Figure 7

[0089] As an embodiment of the present application, based on the position of a single valid visible ranging sensor in the sensor set and its measured distance value to the beam limiter, a single-point guiding adjustment procedure is performed to guide the operator to sequentially adjust the beam limiter to the target projection position along the X-axis and Y-axis directions and to the target SID along the Z-axis, so that the position of the beam limiter approaches the set target point So. Specifically, the procedure can be implemented by steps S d 1061 to step S d 1065, and the details are as follows:

[0090] Step S d 1061: Maintain the stable posture of the beam limiter.

[0091] As in the foregoing embodiments, maintaining the stable posture of the beam limiter means that the data S(a, b, g) remains stable.

[0092] Step S d 1062: Guide the operator to align the light field center of the beam limiter to the single valid visible ranging sensor, at which time the Z coordinate component z of point S is approximately equal to the distance value SD1 of the beam limiter to the single valid visible ranging sensor.

[0093] Here, taking the first valid visible ranging sensor in the sensor set as an example (taking the first ranging sensor in the sensor set as an example in any one of the embodiments of the present application), the distance value SD1 of the beam limiter to the first ranging sensor can be obtained through the interaction between the ranging signal emitter built in the collimation unit of the beam limiter and the first valid visible ranging sensor of the flat panel detector carrier. Figure 2

[0094] Step S d 1063: According to the target SID value, adjust the height of the beam limiter in the Z-axis direction, so that SD1≈SID.

[0095] Step S d ​​1064: Under the constraint of keeping the Y-axis direction fixed and the height of the beam limiter in the Z-axis direction unchanged, guide the operator to move the beam limiter along the X-axis direction, compare the distance value SD1 with the expected distance target value SD1d when the point S is at the center of the X-axis line, and move the beam limiter until SD1≈SD1d.

[0096] Keeping the Y-axis direction fixed means that the Y-axis coordinate of the point S is 0, i.e., y=0, and the height of the beam limiter in the Z-axis direction is unchanged, i.e., the Y-axis coordinate of the point S is always SID. Under this constraint, the expected distance target value SD1d when the point S is at the center of the X-axis line S(W / 2, 0, SID) can be obtained by solving the following equation:

[0097]

[0098] When SD1 is equal to or close to SD1d, it can be considered that the projection of the point S is at the center of the X-axis line, i.e., the coordinates of the point S are (W / 2, 0, SID). Adjust the X direction so that the center of the line is adjusted when the measured value of SD1 is equal to or close to SD1d.

[0099] Step S d 1065: Under the constraint of keeping the X-axis direction fixed and the height of the beam limiter in the Z-axis direction unchanged, guide the operator to move the beam limiter along the Y-axis direction, compare the distance value SD1 with the expected distance target value SD1d when the point S is at the center of the flat panel detector, and move the beam limiter until SD1≈SD1d.

[0100] Keeping the X-axis direction fixed means that the X-axis coordinate of the point S is W / 2, and the height of the beam limiter in the Z-axis direction is unchanged, i.e., the Y-axis coordinate of the point S is always SID. Under this constraint, the expected distance target value SD1d when the point S is at the center of the flat panel detector carrier S can be obtained by solving the following equation:

[0101]

[0102] When the adjustment from the X-axis direction and the Y-axis direction both make SD1 equal to or close to SD1d, it means that the position of the beam limiter approaches the set target point So. After adjustment, the projection of the point S is at the center of the flat panel detector carrier, as shown in the figure, the endpoint of the dashed line coincides with the vertex of the solid triangle, and the positioning is completed. At this time, the collimation degree is best, and the imaging effect is best. Figure 8

[0103] Step S107: Complete collimation when the position of the beam limiter has approached the target point So.

[0104] ​When the collimation is completed when the position of the collimator has approached the target point So, on the one hand, it indicates that the light field is perpendicular to the flat panel detector carrier, and on the other hand, it indicates that the light field is completely coincided with the radiation field of the X-ray, and is in the best photography position. In order to ensure the photography error, the operator can be prompted to observe whether the light field covers the photography site; if the light field covers, a command that the shooting can be performed is generated; if it is not completely covered, a manual fine adjustment guide based on the light field observation is provided; and finally the positioning collimation process is completed after the operator confirms. In this way, the accuracy of the positioning is ensured, the misshooting and wrong shooting are prevented, the collimation degree of the radiation field is ensured to be good, the shooting image quality is ensured to be good, and the diagnostic accuracy is improved.

[0105] It is considered that in the application process, due to different sizes of the flat panel detector, the bias mode can also be different, and the center of the flat panel detector can be offset compared to the center of the flat panel detector carrier, that is, the center of the flat panel detector does not completely coincide with the center of the flat panel detector carrier, as shown in Figure 9 It means that in the foregoing embodiment, the center of the flat panel detector carrier is taken as the center of the flat panel detector for the implementation of the scheme, however, this is an ideal state, and there will be errors between the calculated results and the actual values. Therefore, the method of the foregoing embodiment of the present application can further include: if the center of the flat panel detector has a known fixed offset (a, b, 0) relative to the center of the flat panel detector carrier, that is, in the X-axis, the center of the flat panel detector is different from the center of the flat panel detector carrier by a, and in the Y-axis, the center of the flat panel detector is different from the center of the flat panel detector carrier by b, when the dynamic selection is performed and the corresponding target position calculation and collimator position adjustment strategy is performed, the coordinates of the target point So are adjusted to (W / 2+a, L / 2+b, SID), that is, in all the calculation processes related to the coordinates of So, W / 2+a is used instead of W / 2, and L / 2+b is used instead of L / 2, where W is the characteristic size of the layout of the distance sensor around the flat panel detector carrier in the width direction, L is the characteristic size of the layout of the distance sensor around the flat panel detector carrier in the length direction, as shown in Figure 2 SID is a preset source-image distance.

[0106] From the foregoing Figure 1The flat panel detector positioning and collimation method provided in the example can be known from the technical solutions provided in the present application. On the one hand, by comparing the attitude information (D(α,β,γ) and S(α,β,γ)) of the flat panel detector carrier and the beam limiter in real time, the attitude adjustment instruction is generated until they are consistent, so as to ensure that the X-ray radiation field is always perpendicular to the detector plane, and to avoid image geometric distortion caused by the inclined incidence of the rays from the root. On the other hand, by dynamically monitoring the number of effective visible ranging sensors, and adaptively selecting the positioning strategy based on the number of effective visible ranging sensors, reliable positioning in any occlusion scene is realized, and the industry problem of being unable to position when the flat panel detector is completely occluded is solved. In the third aspect, after the calibrated attitude S(α,β,γ)=D(α,β,γ), the dynamic positioning strategy based on the number of effective visible ranging sensors is established, the attitude calibration and dynamic positioning are integrated into a unified process, the "attitude-position" integrated adjustment is realized, the operation steps are reduced, and the preparation time in wheelchair position / stretcher position and other scenes is shortened. In summary, the technical solutions of the present application realize reliable collimation in a complex occlusion environment through dynamic attitude calibration and occlusion adaptive positioning, and avoid repeated shooting in the DR scene.

[0107] Please refer to the accompanying Figure 10 The digital X-ray photography system provided in the embodiment of the present application includes a flat panel detector carrier 101, a beam limiter 102, and a central processing unit (not shown in the figure), which are described in detail as follows.

[0108] The flat panel detector carrier 101 is placed on the back of the measured object, and integrates a first attitude sensor and a plurality of ranging sensors arranged around the flat panel detector carrier;

[0109] The beam limiter 102 includes a second attitude sensor, a ranging signal emitter, and a light field projection module;

[0110] The central processing unit is configured to: after determining the part to be photographed, the light field projection module covers the part to be photographed, and compares the attitude data D(α,β,γ) and S(α,β,γ) output by the first attitude sensor and the second attitude sensor; when S(α,β,γ)=D(α,β,γ); real-time monitoring of the occlusion state of the ranging sensors around the flat panel detector carrier, obtaining the current effective visible sensor set; based on the effective visible ranging sensors in the sensor set and the distance measurement values obtained based on the ranging sensors and the ranging signal emitter, dynamically selecting and executing the corresponding target position calculation and beam limiter position adjustment strategy, so that the position of the beam limiter approaches the set target point So.

[0111] Figure 11 The structure schematic diagram of the electronic device provided in the embodiment of the present application is shown in FIG. 1. As shown in FIG. 1, Figure 11As shown, the electronic device 11 of the embodiment mainly comprises a processor 110, a memory 111, and a computer program 112 stored in the memory 111 and executable on the processor 110, such as a program of the flat panel detector positioning and collimation method. The processor 110 implements the steps in the above-mentioned flat panel detector positioning and collimation method embodiment when executing the computer program 112, such as Figure 1 The steps S101 to S107 are shown.

[0112] Exemplarily, the computer program 112 of the flat panel detector positioning and collimation method mainly comprises: acquiring the attitude information D(α,β,γ) of the flat panel detector carrier through the attitude sensor built in the flat panel detector carrier and feeding back to the beam limiter collimation unit; acquiring the attitude information S(α,β,γ) of the beam limiter through the beam limiter collimation unit when the beam limiter equipped with the collimation unit is located above the measured object and the light field is opened; guiding the operator to adjust the beam limiter attitude according to the attitude information D(α,β,γ) of the flat panel detector carrier and the attitude information S(α,β,γ) of the beam limiter until S(α,β,γ)=D(α,β,γ), so that the beam limiter light field is perpendicular to the flat panel detector carrier plane; sending the ranging signal to the flat panel detector carrier by the beam limiter collimation unit; monitoring the blocking state of the ranging sensors around the flat panel detector carrier in real time, and acquiring the current effective visible sensor set; based on the effective visible ranging sensors in the sensor set and the received ranging signal, dynamically selecting and executing the corresponding target position calculation and beam limiter position adjustment strategy, so that the position of the beam limiter approaches the set target point So; completing collimation when the position of the beam limiter has approached the target point So. The computer program 112 can be divided into one or more modules / units, one or more modules / units are stored in the memory 111 and executed by the processor 110 to complete the present application. One or more modules / units can be a series of computer program instruction segments capable of completing a specific function, which is used to describe the execution process of the computer program 112 in the electronic device 11.

[0113] The electronic device 11 can include but is not limited to the processor 110, the memory 111. Those skilled in the art can understand that, Figure 11 The electronic device 11 is only an example and does not constitute a limitation on the electronic device 11, and can include more or fewer components than shown, or combine certain components, or different components, for example, the electronic device can also include an input / output device, a network access device, a bus, etc.

[0114] The processor 110 can be a central processing unit (CPU), and can also be other general-purpose processors, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or the like. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0115] The memory 111 can be an internal storage unit of the electronic device 11, such as a hard disk or a memory of the electronic device 11. The memory 111 can also be an external storage device of the electronic device 11, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, or the like, which is equipped on the electronic device 11. Further, the memory 111 can include both the internal storage unit and the external storage device of the electronic device 11. The memory 111 is used to store computer programs and other programs and data required by the electronic device. The memory 111 can also be used to temporarily store data that has been output or will be output.

[0116] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional units and modules is exemplified, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit, and the integrated unit can be realized in the form of hardware or in the form of software functional unit. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the present application. The specific working process of the units and modules in the device can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0117] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can be referred to the related description of other embodiments.

[0118] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0119] In the embodiments provided in the present application, it should be understood that the disclosed apparatuses / devices and methods can be implemented in other ways. For example, the above-described apparatus / device embodiments are merely illustrative, for example, the division of modules or units is merely a logical function division, and there can be another division manner in actual implementation, for example, a plurality of units or components can be combined or integrated into another device, or some features can be ignored or not executed. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0120] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0121] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0122] The integrated modules / units, if implemented in the form of software functional units and sold or used as independent products, can be stored in a storage medium. Based on such understanding, all or part of the processes in the above-mentioned embodiment methods can also be completed by a computer program instructing related hardware, and the computer program of the flat panel detector positioning and collimation method can be stored in a storage medium. When the computer program is executed by a processor, the steps of each method embodiment can be implemented, that is, the attitude information D(α, β, γ) of the flat panel detector carrier is acquired by the attitude sensor built in the flat panel detector carrier and is fed back to the beam limiter collimation unit; when the beam limiter with the collimation unit is located above the measured object and the light field is opened, the attitude information S(α, β, γ) of the beam limiter is acquired by the beam limiter collimation unit; according to the attitude information D(α, β, γ) of the flat panel detector carrier and the attitude information S(α, β, γ) of the beam limiter, the operator is guided to adjust the attitude of the beam limiter until S(α, β, γ) = D(α, β, γ), so that the light field of the beam limiter is perpendicular to the plane of the flat panel detector carrier; the ranging signal is sent from the beam limiter collimation unit to the flat panel detector carrier; the occlusion state of the ranging sensors around the flat panel detector carrier is monitored in real time, and the current effective visible sensor set is acquired; based on the effective visible ranging sensors in the sensor set and the received ranging signal, the corresponding target position calculation and beam limiter position adjustment strategy is dynamically selected and executed, so that the position of the beam limiter approaches the set target point So; when the position of the beam limiter has approached the target point So, the collimation is completed. The computer program includes computer program code, which can be in the form of source code, object code, executable file or some intermediate form, etc. The storage medium can include any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the storage medium does not include electric carrier signal and telecommunication signal.

[0123] The above examples are only used to illustrate the technical solutions of the present application, but not limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application. The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for positioning and aligning a flat panel detector, characterized in that, The method includes: The attitude information D(α,β,γ) of the flat panel detector carrier is obtained by the attitude sensor built into the flat panel detector carrier and fed back to the collimator unit of the beam limiter. When the collimator equipped with the collimation unit is located above the object under test and the optical field is opened, the attitude information S(α,β,γ) of the collimator is obtained through the collimation unit of the collimator. Based on the attitude information D(α,β,γ) of the flat panel detector carrier and the attitude information S(α,β,γ) of the beam limiter, the operator is guided to adjust the attitude of the beam limiter until S(α,β,γ)=D(α,β,γ), so that the optical field of the beam limiter is perpendicular to the plane of the flat panel detector carrier. The beam limiter collimation unit sends a ranging signal to the flat panel detector carrier; The obstruction status of the ranging sensors around the flat panel detector carrier is monitored in real time to obtain the set of currently visible sensors. Based on the effective visible ranging sensors in the sensor set and the ranging signal, the corresponding target position calculation and beam limiter position adjustment strategy are dynamically selected and executed to make the position of the beam limiter approach the set target point So; Collimation is completed when the position of the beam limiter is close to the target point So.

2. The method for positioning and aligning a flat panel detector according to claim 1, characterized in that, The step of dynamically selecting and executing corresponding target position calculation and beam limiter position adjustment strategies based on the effectively visible ranging sensors in the sensor set and the ranging signals, so that the position of the beam limiter approaches the set target point So, includes: Based on the known position coordinates of at least three non-collinear effective visible ranging sensors in the sensor set and their measured distances to the beam limiter, a system of spatial distance equations is constructed. The Euclidean distance formula is used to solve for the current spatial coordinates S(x,y,z) of the beam limiter. The spatial coordinates S(x,y,z) are then compared with the coordinates of the target point So to obtain the position adjustment parameter ΔS(x',y',z'), which brings the position of the beam limiter closer to the set target point So; or Based on the positional relationship between the two effective visible ranging sensors in the sensor set and their measured distances to the beam limiter, a specific axial adjustment procedure is executed to guide the operator to adjust the projection of the beam limiter to a specific point on the straight line formed by the two effective visible ranging sensors, so that the position of the beam limiter approaches the set target point So; or Based on the position of a single effective visible ranging sensor in the sensor set and its measured distance to the beam limiter, a single-point guided adjustment procedure is executed to guide the operator to sequentially adjust the beam limiter to the target projection position along the X-axis and Y-axis and to the target SID along the Z-axis, so that the position of the beam limiter approaches the set target point So.

3. The method for positioning and aligning a flat panel detector according to claim 2, characterized in that, The process of constructing a spatial distance equation system based on the known position coordinates of at least three non-collinear effective visible ranging sensors in the sensor set and their measured distances to the beam limiter, solving for the current spatial coordinates S(x,y,z) of the beam limiter using the Euclidean distance formula, and comparing the spatial coordinates S(x,y,z) with the coordinates of the target point So to obtain the position adjustment parameter ΔS(x',y',z'), so that the position of the beam limiter approaches the set target point So, includes: Obtain the measured distance values ​​SDi from the point S(x,y,z) to each currently visible ranging sensor Oi; Based on the position coordinates Oi(xi,yi,0) of the ranging sensor Oi in the pre-established coordinate system and the Euclidean distance formula... Construct a system of spatial distance equations containing N equations; Solving this system of equations yields the precise spatial coordinates (x, y, z) of the current constrictor. The difference between the coordinate components of point S(x, y, z) and target point So(W / 2, L / 2, SID) is calculated to obtain the position adjustment parameter ΔS(x', y', z') = So – S. When ΔS(x', y', z') approaches 0, the position of the clamping device approaches the set target point So.

4. The method for positioning and aligning a flat panel detector according to claim 2, characterized in that, In the sensor set, two effective visible ranging sensors are located on the same sideline of a rectangular area. Based on the positional relationship between the two effective visible ranging sensors and their measured distances to the beam limiter, a specific axial adjustment procedure is executed to guide the operator to adjust the projection of the beam limiter to a specific point on the straight line formed by the two effective visible ranging sensors, so that the position of the beam limiter approaches the set target point. So includes: Maintain the stability of the beam limiter attitude; The operator is guided to move the beam limiter in a direction perpendicular to the edge line, and the distance values ​​SD1 and SD2 from the beam limiter to the two effective visible ranging sensors are monitored in real time. When SD1 and SD2 reach their minimum values ​​simultaneously, the movement of the constraint device stops. At this time, S is projected onto the edge line, and the coordinates of the projection point satisfy the constraint condition of y=0 or x=0. Based on the position coordinates of the two effective visible ranging sensors, the distance values ​​SD1 and SD2, and the constraints, a system of equations is constructed. Find the coordinates (x, y, z) of the current point S; Calculate the coordinate component differences between the current point S (x, y, z) and the target point So (W / 2, L / 2, SID) to obtain the position adjustment parameter ΔS(x', y', z') = So - S. When ΔS(x', y', z') approaches 0, the position of the limiter approaches the set target point So.

5. The method for positioning and aligning a flat panel detector according to claim 2, characterized in that, In the sensor set, two effective visible ranging sensors are located on the diagonal of a rectangular area. Based on the position of a single effective visible ranging sensor in the sensor set and its measured distance to the beam limiter, a single-point guided adjustment procedure is executed. This guides the operator to sequentially adjust the beam limiter along the X and Y axes to the target projection position and along the Z axis to the target SID, making the position of the beam limiter approach the set target point S0. This includes: Maintain the stability of the beam limiter attitude; The operator is guided to move the beam limiter in a direction perpendicular to the diagonal, and the distance values ​​SD1 and SD3 from the beam limiter to the two effective visible ranging sensors are monitored in real time. When SD1 and SD3 both reach their minimum values, the movement stops, and at this time, point S is projected onto the diagonal. The operator is guided to move the clamping device along a direction parallel to the diagonal based on the relative magnitudes of SD1 and SD3. The movement stops when SD1≈SD3. At this time, the projection of point S is located at the center of the diagonal. Based on the position coordinates and distance values ​​SD1 and SD3 of the two effective visible ranging sensors, and the projection constraints of point S (x = W / 2, y = L / 2), a system of equations is constructed. Find the coordinates of the current point S (x = W / 2, y = L / 2, z); Calculate the coordinate component differences between the current point S (x = W / 2, y = L / 2, z) and the target point So (W / 2, L / 2, SID) to obtain the position adjustment parameter ΔS(x',y',z') = So.zz = SID - z. When ΔS(x',y',z') approaches 0, the position of the limiter approaches the set target point So.

6. The method for positioning and aligning a flat panel detector according to claim 2, characterized in that, The step of executing a single-point guided adjustment procedure based on the position of a single effective visible ranging sensor in the sensor set and its measured distance to the beam limiter, guiding the operator to sequentially adjust the beam limiter to the target projection position along the X-axis and Y-axis and to the target SID along the Z-axis, so that the position of the beam limiter approaches the set target point So, includes: Maintain the attitude stability of the beam limiter; The operator is guided to align the center of the optical field of the beam limiter with the single effective visible ranging sensor. At this time, the Z coordinate component z of point S is approximately equal to the distance SD1 from the beam limiter to the single effective visible ranging sensor. Adjust the height of the clamp in the Z-axis direction according to the target SID value so that SD1≈SID; While keeping the Y-axis direction fixed and the height of the limiter in the Z-axis direction constant, guide the operator to move the limiter along the X-axis direction. Using the expected target distance SD1d when point S is at the center of the X-axis edge, compare the distance SD1 with the target value SD1d, and move the limiter until SD1≈SD1d. While keeping the X-axis direction fixed and the height of the beam limiter in the Z-axis direction constant, guide the operator to move the beam limiter along the Y-axis direction. Using the expected distance target value SD1d when the target point So is at the center of the flat panel detector, compare the distance value SD1 with the target value SD1d, and move the beam limiter until SD1≈SD1d.

7. The method for positioning and aligning a flat panel detector according to claim 2, characterized in that, If the center of the flat panel detector has a known fixed offset (a, b, 0) relative to the center of the flat panel detector carrier, then when performing dynamic selection and executing the corresponding target position calculation and limiter position adjustment strategy, the coordinates of the target point So are adjusted to (W / 2+a, L / 2+b, SID), where W is the width direction characteristic dimension of the ranging sensor layout around the flat panel detector carrier, L is the length direction characteristic dimension of the ranging sensor layout around the flat panel detector carrier, and SID is the preset source-image distance.

8. A digital X-ray imaging system, characterized in that, Includes a flat panel detector carrier, a beam limiter, and a central processing unit; The flat panel detector carrier is placed on the back of the object being measured, and integrates a first attitude sensor and several ranging sensors deployed around the flat panel detector carrier. The beam limiter includes a second attitude sensor, a ranging signal transmitter, and a light field projection module; The central processing unit is configured as follows: after determining the area to be photographed, the light field projection module covers the area to be photographed, and compares the attitude data D(α,β,γ) and S(α,β,γ) output by the first attitude sensor and the second attitude sensor; when S(α,β,γ)=D(α,β,γ); monitors in real time the occlusion status of the ranging sensors around the flat panel detector carrier, and obtains the currently effectively visible sensor set; based on the effectively visible ranging sensors in the sensor set and the distance measurement values ​​obtained by the ranging sensors and the ranging signal transmitter, dynamically selects and executes the corresponding target position calculation and beam limiter position adjustment strategy, so that the position of the beam limiter approaches the set target point So.

9. An electronic device, the device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 7.

10. A storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 7.

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