Indication method, indication system and X-ray imaging system

Abstract

The present invention provides an indication method for indicating the position of X-rays incident on an ionization chamber on a subject. The indication method includes: emitting an indication light beam that can propagate within the subject positioning space, and the indication light beam is visible light. The indication light beam is arranged to be able to form an indication light and shadow on the surface of the subject, and the indication light and shadow are used to indicate the coverage area of the X-rays incident on each ionization chamber on the surface of the subject. This indication method is conducive to more accurately selecting the sampling ionization chamber. In addition, an indication system and an X-ray imaging system for implementing this indication method are also provided.

Description

Technical Field

[0001] The present invention relates to the field of X-ray imaging, and in particular to an indication method for indicating the position of X-rays directed at an ionization chamber on a subject, and an indication system and an X-ray imaging system for implementing the indication method. Background Art

[0002] In X-ray imaging, automatic exposure control plays a very important role in improving image quality. Automatic exposure control requires selecting a suitable sampling ionization chamber. To facilitate the user to understand the position of the ionization chamber, the corresponding area of the ionization chamber is marked on the surface of the existing chest radiograph stand. The user can only make a selection based on experience in combination with these marks, and the accuracy of the selection is not ideal, which affects the imaging quality. Summary of the Invention

[0003] An object of the present invention is to provide an indication method that can indicate the position of X-rays directed at an ionization chamber on a subject, which is beneficial for more accurately selecting a sampling ionization chamber.

[0004] Another object of the present invention is to provide an indication system that can indicate the position of X-rays directed at an ionization chamber on a subject, which is beneficial for more accurately selecting a sampling ionization chamber.

[0005] Still another object of the present invention is to provide an X-ray imaging system that can indicate the position of X-rays directed at an ionization chamber on a subject, which is beneficial for more accurately selecting a sampling ionization chamber.

[0006] The present invention provides an indication method for indicating the position of X-rays directed at an ionization chamber on a subject. The indication method includes: emitting an indication light beam that can propagate in the subject positioning space, and the indication light beam is visible light. The indication light beam is arranged to be able to form an indication light and shadow on the surface of the subject, and the indication light and shadow is used to indicate the coverage area of the X-rays directed at each ionization chamber on the surface of the subject.

[0007] This indication method can indicate the position of X-rays directed at each ionization chamber on the subject in a visible light manner. Using this as a basis for selecting a sampling ionization chamber is beneficial for more accurately selecting a sampling ionization chamber.

[0008] In another illustrative embodiment of the indication method, the indication method includes: emitting a source light beam directed at the subject positioning space, the source light beam being visible light, and arranging a light shielding module on the optical path before the source light beam reaches the subject positioning space, and the light shielding module can partially block the source light beam to form an indication light beam. This is convenient for implementation and beneficial for cost savings.

[0009] In still another illustrative embodiment of the indication method, the optical path of the source light beam in the subject positioning space is the same as that of the X-rays. This is beneficial for simplifying the setting of the light shielding module.

[0010] In still another exemplary embodiment of the indicating method, the light shielding module is a light shielding plate perpendicular to the optical axis of the source beam. The light shielding plate has several fixed light shielding regions. Each fixed light shielding region corresponds to an ionization chamber. Each fixed light shielding region can form a visible light shadow in the ionization chamber incident plane for indicating the region corresponding to its corresponding ionization chamber. The structure of this light shielding module is simple, which is conducive to cost saving.

[0011] In still another exemplary embodiment of the indicating method, a light shielding module is provided on the optical path before the source beam reaches the subject positioning space, specifically including:

[0012] On the optical path before the source beam reaches the subject positioning space, a light shielding plate capable of moving along the optical axis of the source beam is provided. The light shielding plate is arranged such that when the distance from the tube focus to the ionization chamber incident plane is a standard distance, the light shielding plate at the standard position can form a visible light shadow that coincides with the boundaries of each ionization chamber in the ionization chamber incident plane; and

[0013] The target distance from the light shielding plate to the source beam focus is calculated according to formula (1), and the position of the light shielding plate is adjusted along the optical axis of the source beam according to the target distance to meet the target distance.

[0014] SGD = SID * m / M formula (1),

[0015] where SGD is the target distance from the source beam focus to the light shielding plate, SID is the actual distance from the tube focus to the ionization chamber incident plane, m is the overall width of all fixed light shielding regions, and M is the overall width of all ionization chambers. Thus, when the distance from the tube focus to the ionization chamber incident plane changes, the position of the light shielding module can be adjusted accordingly without replacing the light shielding module. This can save costs.

[0016] In still another exemplary embodiment of the indicating method, a light shielding module is provided on the optical path before the source beam reaches the subject positioning space, specifically including: on the optical path before the source beam reaches the subject positioning space, a translatable light shielding module is provided. The light shielding module is arranged such that when the distance from the tube focus to the ionization chamber incident plane is a standard distance, the light shielding module at the standard position can form a visible light shadow that coincides with the boundaries of each ionization chamber in the ionization chamber incident plane; obtaining the maximum distance from the subject's surface to the ionization chamber incident plane; and adjusting the spatial position of the light shielding module according to the maximum distance so that the indicating light and shadow can indicate the coverage area of the X-rays directed at each ionization chamber on the subject's surface. This can make the position setting of the source beam more flexible.

[0017] In still another exemplary embodiment of the indicating method, the indicating method further includes: selecting a sampling ionization chamber according to the indicating light and shadow formed on the subject's surface. This is conducive to improving the quality of X-ray imaging.

[0018] In still another exemplary embodiment of the indication method, a sampling ionization chamber is selected according to the indication light and shadow formed on the surface of the subject. Specifically, for each ionization chamber, according to the indication light and shadow formed on the surface of the subject, the proportion of the projection area of the part of the indication light and shadow corresponding to the ionization chamber in the ionization chamber incident plane along the X-ray irradiation direction in the area of the ionization chamber in the ionization chamber incident plane is analyzed, and then the sampling ionization chamber is selected according to the analysis result. This method is simple and easy to implement.

[0019] In still another exemplary embodiment of the indication method, a sampling ionization chamber is selected according to the indication light and shadow formed on the surface of the subject. Specifically, the indication light and shadow formed on the surface of the subject are sensed by a sensor. For each ionization chamber, according to the sensing result of the sensor, the proportion of the projection area of the part of the indication light and shadow corresponding to the ionization chamber in the ionization chamber incident plane along the X-ray irradiation direction in the area of the ionization chamber in the ionization chamber incident plane is analyzed, and then the sampling ionization chamber is selected according to the analysis result. Using a sensor helps to avoid errors caused by the user's naked-eye observation.

[0020] In still another exemplary embodiment of the indication method, the sampling ionization chamber is selected according to the analysis result. Specifically:

[0021] The ionization chamber with a proportion of 100% is selected as the sampling ionization chamber; or among the ionization chambers with a proportion of 100%, the ionization chamber farthest from the edge of the projection of the subject along the X-ray propagation direction in the ionization chamber incident plane is selected as the sampling ionization chamber; and / or

[0022] If the highest value of the proportions of the ionization chambers is less than 100% and greater than or equal to a set threshold, the sampling ionization chamber is selected according to the value of the proportion and the dose threshold of the sampling ionization chamber in the automatic exposure control system is adjusted; and / or

[0023] If the proportions of all the ionization chambers are less than a set threshold, the subject is prompted to reposition.

[0024] Wherein, if the highest value of the proportions of the ionization chambers is less than 100% and greater than or equal to a set threshold, selecting the sampling ionization chamber according to the value of the proportion and adjusting the dose threshold of the sampling ionization chamber in the automatic exposure control system specifically includes:

[0025] If the highest value of the said ratio of each ionization chamber is lower than 100% and greater than or equal to the first value, then the ionization chamber with the highest ratio is taken as the sampling ionization chamber, and the lookup table is queried according to the highest value of the ratio; if there is a corresponding query ratio value in the lookup table, a unique query coefficient is obtained and taken as the calculation coefficient of the sampling ionization chamber; if there is no corresponding query ratio value in the lookup table, then look up the table according to the two query ratio values closest to the said ratio to obtain two query coefficients, and then calculate the coefficient corresponding to the said ratio by interpolation method and take it as the calculation coefficient of the sampling ionization chamber;

[0026] If the highest value of the ratio of each ionization chamber is lower than the first value and greater than or equal to the second value, and the ratio of at least two ionization chambers is less than the first value and greater than or equal to the second value, then the ionization chambers with the ratio less than the first value and greater than or equal to the second value are taken as the sampling ionization chambers. For each ionization chamber taken as the sampling ionization chamber, the coefficient corresponding to each ionization chamber is obtained according to the method of the said lookup table, and the mean value of these coefficients is calculated and taken as the calculation coefficient of the sampling ionization chamber.

[0027] The present invention also provides an indication system for indicating the position of the X-ray irradiating the ionization chamber on the subject. The indication system can emit an indication light beam propagating in the subject positioning space, and the indication light beam is a visible light. The indication light beam can form an indication light and shadow on the surface of the subject, and the indication light and shadow is used to indicate the coverage area of the X-ray irradiating each ionization chamber on the surface of the subject. The indication system can indicate the position of the X-ray irradiating the ionization chamber on the subject in the way of visible light, and this is used as the basis for selecting the sampling ionization chamber, which is conducive to more accurately selecting the sampling ionization chamber.

[0028] In another schematic embodiment of the indication system, the indication system includes a visible light generation module and a light shielding module. The visible light generation module can emit a source light beam directed to the subject positioning space, and the source light beam is a visible light. The light shielding module is arranged on the light path before the source light beam reaches the subject positioning space and can partially block the source light beam to form an indication light beam. This is conducive to cost saving.

[0029] In still another schematic embodiment of the indication system, the source light beam is consistent with the light path of the X-ray in the subject positioning space. This is conducive to simplifying the setting of the light shielding module.

[0030] In still another schematic embodiment of the indication system, the light shielding module is a light shielding plate perpendicular to the optical axis of the source light beam. The light shielding plate has several fixed light shielding areas. Each fixed light shielding area corresponds to an ionization chamber. Each fixed light shielding area can form a visible light shadow for indicating the area of its corresponding ionization chamber on the ionization chamber incident plane. The structure of this light shielding module is simple and is conducive to cost saving.

[0031] In still another illustrative embodiment of the indication system, the light shield can move relative to the visible light generation module along the optical axis of the source beam. The light shield is arranged such that when the distance from the tube focus to the ionization chamber entrance plane is a standard distance, the light shield at the standard position can form a visible light shadow on the ionization chamber entrance plane that coincides with the boundaries of the respective ionization chambers. Thereby, when the distance from the tube focus to the ionization chamber entrance plane changes, it is only necessary to correspondingly adjust the position of the light shielding module, without replacing the light shielding module.

[0032] In still another illustrative embodiment of the indication system, the indication system further includes a driving module and a control module. The driving module can drive the light shield to move along the optical axis of the source beam. The control module can calculate the target distance from the light shield to the source beam focus according to formula (1), and can control the driving module according to the target distance so that the driving module drives the light shield to move to meet the target distance.

[0033] SGD = SID*m / M Formula (1),

[0034] where SGD is the target distance from the source beam focus to the light shield, SID is the actual distance from the tube focus to the ionization chamber entrance plane, m is the overall width of all fixed light shielding areas, and M is the overall width of all ionization chambers. By setting the driving module and the control module, automatic adjustment can be achieved.

[0035] In still another illustrative embodiment of the indication system, the light shielding module can translate relative to the visible light generation module. The light shielding module is arranged such that when the distance from the tube focus to the ionization chamber entrance plane is a standard distance, the light shielding module at the standard position can form a visible light shadow on the ionization chamber entrance plane that coincides with the boundaries of the respective ionization chambers. The indication system further includes a driving module and a control module. The driving module can drive the light shielding module to translate. The control module can obtain the maximum distance from the surface of the subject to the ionization chamber entrance plane, and control the driving module according to the maximum distance to adjust the spatial position of the light shielding module, so that the indication light and shadow can indicate the coverage area of the X-rays directed at each ionization chamber on the surface of the subject. Thereby, the position setting of the source beam can be made more flexible.

[0036] In still another illustrative embodiment of the indication system, the indication system further includes a sensor. The sensor is used to sense the indication light and shadow formed on the surface of the subject. The control module can, for each ionization chamber, based on the sensing result of the sensor, analyze the proportion of the projection area of the part of the indication light and shadow corresponding to the ionization chamber along the X-ray irradiation direction on the ionization chamber entrance plane in the area of the ionization chamber on the ionization chamber entrance plane, and then select the sampling ionization chamber according to the analysis result. This helps to improve the automation of the selection of the sampling ionization chamber.

[0037] In still another illustrative embodiment of the indication system, the control module is set as:

[0038] Select the ionization chamber with a ratio of 100% as the sampling ionization chamber; or among the ionization chambers with a ratio of 100%, select the ionization chamber that is farthest from the edge of the projection of the distance from the subject along the X-ray propagation direction on the incident plane of the ionization chamber as the sampling ionization chamber; and / or

[0039] If the highest value of the ratios of the ionization chambers is lower than 100% and greater than or equal to a set threshold, select the sampling ionization chamber according to the ratio value and adjust the dose threshold of the sampling ionization chamber in the automatic exposure control system; and / or

[0040] If the ratios of all ionization chambers are less than a set threshold, prompt the subject to reposition.

[0041] The present invention also provides an X-ray imaging system, which includes the above-mentioned indication system. The indication system is used, for example, after the subject's positioning is completed and before the X-ray is emitted. The indication system can indicate the position of the X-ray irradiating the ionization chamber on the subject in the form of visible light, and use this as the basis for selecting the sampling ionization chamber, which is conducive to more accurately selecting the sampling ionization chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The following drawings only schematically illustrate and explain the present invention, and do not limit the scope of the present invention.

[0043] Figure 1 It is a schematic diagram for illustrating a schematic embodiment of the indication method.

[0044] Figure 2 It is a flowchart of setting the light-shielding module in a schematic embodiment of the indication method.

[0045] Figure 3 For auxiliary explanation Figure 2 The method of setting the light-shielding module shown.

[0046] Figure 4 It is a flowchart of setting the light-shielding module in another schematic embodiment of the indication method.

[0047] Figure 5 It is a schematic structural diagram for illustrating a schematic embodiment of the indication system.

[0048] LABEL DESCRIPTION

[0049] 10 Visible light generation module

[0050] 11 LED lamp

[0051] 12 Reflecting mirror

[0052] 30 Light-shielding module

[0053] 31 Fixed light-shielding area

[0054] 40 Transmission mechanism

[0055] 50 Driving module

[0056] 60 Control module

[0057] 70 Sensor

[0058] 80 Ionization chamber

[0059] 90 X-ray tube

[0060] F Incident plane of ionization chamber

[0061] P1 X-ray tube focus

[0062] P2 Source beam focus

[0063] K Subject positioning space

[0064] A Optical axis of source beam

[0065] B Source beam

[0066] P Indicating beam

[0067] W Width direction. Detailed implementation manners

[0068] For a clearer understanding of the technical features, objectives, and effects of the invention, the detailed implementation manners of the invention are now described with reference to the accompanying drawings. In the drawings, the same reference numerals denote components having the same or similar structures but the same functions.

[0069] In this document, "schematic" means "serving as an example, instance, or illustration", and any illustration or implementation manner described as "schematic" in this document should not be construed as a more preferred or more advantageous technical solution.

[0070] For the sake of simplicity of the drawings, only the parts related to the invention are schematically shown in each drawing, and they do not represent the actual structure of the product.

[0071] The indication method provided by the present invention is used to indicate the position of the X-ray directed at the ionization chamber on the subject during X-ray imaging, which is used as the basis for selecting the sampling ionization chamber. Among them, the "X-ray directed at the ionization chamber" refers to the part of the X-ray whose propagation path passes through the ionization chamber during the X-ray imaging process. The "position of the X-ray directed at the ionization chamber on the subject" is the position where the X-ray directed at the ionization chamber intersects the subject during the X-ray imaging process. The "sampling ionization chamber" refers to the ionization chamber used by the automatic exposure control (AEC) system during one X-ray imaging to determine the exposure time. Usually, the automatic exposure control (AEC) system will set three or five ionization chambers, and it is necessary to determine which / which ionization chamber is used as the sampling ionization chamber according to the actual situation during X-ray imaging.

[0072] Figure 1 It is a schematic diagram for illustrating a schematic implementation manner of the indication method. As Figure 1 shown, the indication method includes: emitting an indication beam P that can propagate within the subject positioning space K, and the indication beam P is visible light. The indication beam P is set to be able to form an indication light and shadow on the surface of the subject after positioning is completed, and this indication light and shadow is used to indicate the coverage area of the X-ray directed at each ionization chamber 80 on the surface of the subject, or it can also be understood that this indication light and shadow is used to indicate the area where the X-ray directed at each ionization chamber 80 intersects the surface of the subject.

[0073] Specifically, as Figure 1 shown, in this schematic implementation manner, the indication method includes: emitting a source beam B directed at the subject positioning space K, and the source beam B is visible light. The source beam B is emitted by a visible light generation module 10, for example. The visible light generation module 10 includes, for example, an LED lamp 11 and a reflector 12, but is not limited thereto. The indication method further includes: arranging a light shielding module 30 on the optical path before the source beam B reaches the subject positioning space K. The light shielding module 30 can partially block the source beam B to form the indication beam P.

[0074] Among them, the "subject positioning space K" is a spatial range that extends a certain distance towards the X-ray tube 90 starting from the ionization chamber incident plane F, and it is the spatial range for the subject to place the body and maintain a specific position during X-ray imaging. The "ionization chamber incident plane F" refers to the plane where the surface of the ionization chamber 80 for X-ray entry is located. The "subject after positioning is completed" is the subject who has been in a specific position and location on the X-ray examination equipment according to the requirements of medical imaging examinations.

[0075] This indication method is implemented, for example, after the subject positioning is completed and before the X-ray is emitted. This indication method can indicate the position of the X-ray directed at each ionization chamber on the subject in a visible light manner. Using this as the basis for selecting the sampling ionization chamber is conducive to more accurately selecting the sampling ionization chamber.

[0076] In this exemplary embodiment, an indicating beam P is formed by a source beam B and a light-shielding module 30, which is easy to implement and helps save costs, but is not limited thereto. In other exemplary embodiments, the indicating beam P may also be emitted by a combined light source, which is composed of several individual light sources. An individual light source is, for example, a point light source or a collimated light source. By adjusting the on / off states of the individual light sources, the adjustment of the indicating beam P can be achieved. In this way, the light-shielding module can be omitted.

[0077] In this exemplary embodiment, the source beam B is, for example, consistent with the optical path of the X-ray in the subject positioning space K, that is, the source beam B and the part of the X-ray in the subject positioning space K can be regarded as emitted by a point light source located at the same position. This helps simplify the setting of the light-shielding module 30. Specifically, as Figure 1 shown, in this exemplary embodiment, the part of the visible light emitted by the LED lamp 11 after being reflected by the mirror 12 is consistent with the part of the optical path of the X-ray emitted by the X-ray tube 90 passing through the mirror 12. By setting the mirror 12, the problem of the position conflict between the LED lamp 11 and the X-ray tube 90 can be avoided. In other exemplary embodiments, the source beam B in the subject positioning space K may also be inconsistent with the optical path of the X-ray.

[0078] See Figure 1 , in this exemplary embodiment, the light-shielding module 30 is a light-shielding plate perpendicular to the optical axis A of the source beam B. In this exemplary embodiment, the source beam B and the X-ray beam are, for example, conical beams. Figure 1 In, the part of the optical axis A of the source beam B below the mirror 12 overlaps with the X-ray optical axis. The light-shielding plate has five fixed light-shielding regions 31 ( Figure 1 the light-shielding regions 31 are represented by the dark regions on the light-shielding module 30 in). Each fixed light-shielding region 31 corresponds to an ionization chamber 80 (five ionization chambers 80 are taken as an example in this exemplary embodiment). When the subject has not entered the subject positioning space K, each fixed light-shielding region 31 can form a visible light shadow in the ionization chamber incident plane F for indicating the region corresponding to its corresponding ionization chamber 80 ( Figure 1 represented by the dark regions on the ionization chamber incident plane F in). This light-shielding module has a simple structure and helps save costs. In an exemplary embodiment, the light-shielding plate is, for example, a glass plate coated with a light-shielding coating in the fixed light-shielding regions 31, but is not limited thereto.

[0079] In this exemplary embodiment, five ionization chambers 80 are taken as an example, so five fixed light-shielding regions 31 are correspondingly set. In other exemplary embodiments, the number of the fixed light-shielding regions 31 can be adjusted correspondingly with the number of the ionization chambers 80.

[0080] See Figure 2, in a schematic embodiment, a light-shielding module 30 is disposed on the optical path before the source beam B reaches the subject positioning space K, specifically including steps S11 and S12.

[0081] S11: On the optical path before the source beam B reaches the subject positioning space K, a light-shielding plate capable of moving along the optical axis A of the source beam B is disposed. Refer to Figure 3 , the light-shielding plate is arranged such that when the distance from the tube focus P1 to the ionization chamber incident plane F is a standard distance, the light-shielding plate at the standard position can form a visible light shadow coinciding with the boundaries of each ionization chamber on the ionization chamber incident plane F when the subject has not entered the subject positioning space, that is, the position where the light-shielding plate can form a visible light shadow coinciding with the boundaries of each ionization chamber on the ionization chamber incident plane F is the "standard position". This "standard distance" is artificially set, for example, within the common distance range from the tube focus to the ionization chamber incident plane, and can be specifically adjusted as needed.

[0082] S12: Calculate the target distance from the light-shielding plate of the light-shielding module 30 to the source beam focus P2 according to formula (1), and adjust the position of the light-shielding plate along the optical axis A of the source beam B according to the target distance to meet the target distance.

[0083] SGD = SID * m / M formula (1),

[0084] wherein, SGD is the target distance along the optical axis A of the source beam B from the source beam focus P2 to the light-shielding plate of the light-shielding module 30 (refer to Figure 3 , since in this schematic embodiment, the optical path of the source beam B in the subject positioning space K is the same as that of the X-ray, so SGD is equal to the distance from the tube focus P1 to the light-shielding module 30), SID is the actual distance from the tube focus P1 to the ionization chamber incident plane F, m is the overall width of all fixed light-shielding regions in the width direction W, M is the overall width of all ionization chambers in the width direction W, and the width direction W is parallel to the ionization chamber incident plane F.

[0085] Thereby, when the distance from the tube focus P1 to the ionization chamber incident plane F changes, it is only necessary to correspondingly adjust the position of the light-shielding module 30, and there is no need to replace the light-shielding module 30. This can save costs. It can be understood that the adjustment of the light-shielding module 30 on the basis of the standard position will partially lose the indication accuracy, but usually the change in the distance from the tube focus P1 to the ionization chamber incident plane F is limited, and such accuracy loss is acceptable. When in use, the position of the light-shielding module 30 only needs to be adjusted according to the distance from the tube focus P1 to the ionization chamber incident plane F, and there is no need to adjust according to different subjects, which is the benefit brought by the fact that the optical path of the source beam B in the subject positioning space K is the same as that of the X-ray, for example.

[0086] In other exemplary embodiments, when the distance from the tube focal point P1 to the incident plane F of the ionization chamber is fixed, the light shielding module 30 only needs to be set such that, when the subject has not entered the subject positioning space, a visible light shadow that coincides with the boundaries of the ionization chambers can be formed on the incident plane F of the ionization chamber, and its position remains fixed.

[0087] In other exemplary embodiments, the source light beam may also not coincide with the X-ray optical path within the subject positioning space. In this case, as Figure 4 shown, a light shielding module is provided on the optical path before the source light beam reaches the subject positioning space, specifically including steps S21 to S23.

[0088] S21: On the optical path before the source light beam reaches the subject positioning space, a translatable light shielding module is provided. The light shielding module is configured such that when the distance from the tube focal point to the incident plane of the ionization chamber is a standard distance, the light shielding module at the standard position can form a visible light shadow on the incident plane of the ionization chamber that coincides with the boundaries of the ionization chambers.

[0089] S22: Obtain the maximum distance from the surface of the subject to the incident plane of the ionization chamber. This distance can be obtained, for example, by a camera, TOF, radar, etc. through recognition and measurement, or can be obtained by estimating the body thickness based on the height and weight of the subject.

[0090] S23: Adjust the spatial position of the light shielding module according to the maximum distance, so that the indicated light and shadow can indicate the coverage area of the X-rays directed at each ionization chamber on the surface of the subject. This enables the position of the source light beam to be set more flexibly.

[0091] Adjust the spatial position of the light shielding module according to the maximum distance from the surface of the subject to the incident plane of the ionization chamber, so that the indicated light and shadow can indicate the coverage area of the X-rays directed at each ionization chamber on the surface of the subject. Specifically: According to the maximum distance from the surface of the subject to the incident plane of the ionization chamber and the distance from the tube focal point to the incident plane of the ionization chamber, calculate the spatial position of the light shielding module by looking up a table. Since the positions of the tube focal point and the source light beam focal point are both known and determined, they project X-rays and visible light onto the ionization chamber at different positions respectively. Thus, when the position of the subject's surface is known, the specific position of the light shielding module can be determined, and the relationship between this position and the maximum distance from the surface of the subject to the incident plane of the ionization chamber and the distance from the tube focal point to the incident plane of the ionization chamber can be pre-recorded. In this way, the spatial position of the light shielding module can be quickly obtained by looking up the table. In this embodiment, the translation of the light shielding module is not only along the optical axis direction, but also includes the direction perpendicular to the optical axis, and this direction perpendicular to the optical axis is generally the connection line between the tube focal point and the LED lamp.

[0092] In another illustrative embodiment of the indication method, the indication method further includes: selecting a sampling ionization chamber according to the indication light and shadow formed on the surface of the subject, which is conducive to improving the quality of X-ray imaging.

[0093] Specifically, selecting a sampling ionization chamber according to the indication light and shadow formed on the surface of the subject is specifically as follows: for each ionization chamber, according to the indication light and shadow formed on the surface of the subject, analyze the proportion of the projection area of the part corresponding to the ionization chamber in the indication light and shadow along the X-ray irradiation direction on the incident plane of the ionization chamber in the area of the ionization chamber on the incident plane of the ionization chamber, and then select the sampling ionization chamber according to the analysis result. This method is simple and easy to implement.

[0094] Among them, for example, the indication light and shadow formed on the surface of the subject are sensed by a sensor, and subsequent analysis is performed according to the sensing result of the sensor. The sensor is, for example, a camera, but is not limited thereto. Using a sensor helps to avoid errors caused by the naked eye observation of the user. In other illustrative embodiments, it is also possible to observe with the naked eye of the user and perform manual analysis to obtain this proportion (since the resolution of the naked eye observation is limited, the obtained result is, for example, a proportion of 100% or not 100%).

[0095] Specifically, the method of selecting a sampling ionization chamber according to the analysis result is, for example, as described below.

[0096] If there is an ionization chamber with a proportion of 100%, all ionization chambers with a proportion of 100% are selected as sampling ionization chambers, but are not limited thereto. In other illustrative embodiments, it may also be that if there is an ionization chamber with a proportion of 100%, among the ionization chambers with a proportion of 100%, the ionization chamber farthest from the edge of the projection of the subject along the X-ray propagation direction on the incident plane of the ionization chamber is selected as the sampling ionization chamber. This helps to improve the quality of X-ray imaging.

[0097] If the highest value of the proportion of each ionization chamber is less than 100% and greater than or equal to a set threshold value, the sampling ionization chamber is selected according to the value of the proportion and the dose threshold of the sampling ionization chamber in the automatic exposure control system is adjusted. The set threshold value is, for example, set according to experience. This can reduce the probability of the subject being repositioned and improve the comfort of the subject during the examination.

[0098] The set threshold value is, for example, 90%, but is not limited thereto. Specifically, for example, it includes:

[0099] 1. Set up a query table, which includes query ratio values, corresponding body parts, subject data (such as body thickness), and query coefficients. The query ratio value refers to the value indicating the ratio of the projection area of the part corresponding to a single ionization chamber in the light and shadow along the X-ray irradiation direction on the incident plane of the ionization chamber to the area of the ionization chamber on the incident plane of the ionization chamber. The corresponding body part refers to the part on the subject's body where the part corresponding to a single ionization chamber in the light and shadow falls. The body thickness refers to the average thickness of the corresponding body part along the direction perpendicular to the incident plane of the ionization chamber. The query coefficient is multiplied by the original dose threshold to obtain the adjusted dose threshold. The query coefficient is a value less than 1. The original dose threshold is, for example, the dose threshold when the ratio of the ionization chamber is 100%, which is an empirically set value by humans. The adjusted dose threshold is used as the actual dose threshold during actual exposure. In this query table, the corresponding query coefficient can be found according to the query ratio value, the corresponding body part, and the subject data (such as body thickness).

[0100] 2. If the highest value of the ratio of each ionization chamber is lower than 100% and greater than or equal to a first value (such as 95%), then the ionization chamber with the highest ratio is used as the sampling ionization chamber, and the query table is queried according to the highest value of the ratio. If there is a corresponding query ratio value in the query table, a unique query coefficient is obtained and used as the calculation coefficient of the sampling ionization chamber. If there is no corresponding query ratio value in the query table, then look up the table according to the two query ratio values closest to the ratio, obtain two query coefficients, and then calculate the coefficient corresponding to the ratio by interpolation method, and use it as the calculation coefficient of the sampling ionization chamber.

[0101] 3. If the highest value of the ratio of each ionization chamber is lower than the first value (such as 95%) and greater than or equal to a second value (the second value is less than the first value, such as 90%), and only one ionization chamber has a ratio less than the first value 95% and greater than or equal to the second value 90%, then the ionization chamber with the highest ratio is used as the sampling ionization chamber, and the coefficient corresponding to the ionization chamber with the highest ratio is obtained according to the method in item 2 and used as the calculation coefficient of the sampling ionization chamber.

[0102] 4. If the highest value of the ratio of each ionization chamber is lower than the first value 95% and greater than or equal to the second value 90%, and at least two ionization chambers have a ratio less than the first value 95% and greater than or equal to the second value 90%, then the ionization chambers with a ratio less than the first value 95% and greater than or equal to the second value 90% are used as sampling ionization chambers. For each ionization chamber used as a sampling ionization chamber, the coefficient corresponding to each ionization chamber is obtained according to the method in item 2, and the mean value of these coefficients is calculated and used as the calculation coefficient of the sampling ionization chamber.

[0103] 5. Multiply the obtained calculation coefficient by the original dose threshold of the sampling ionization chamber to obtain the adjusted dose threshold of the sampling ionization chamber. This helps to improve the quality of X-ray imaging.

[0104] If the ratio of each ionization chamber is less than the set threshold, the subject is prompted to reposition. In other exemplary embodiments, if there is no ionization chamber with a ratio of 100%, the subject is prompted to reposition.

[0105] The present invention also provides an indication system for implementing the above indication method. The indication system can emit an indication light beam propagating in the subject's positioning space, and the indication light beam is visible light. The indication light beam can form an indication light shadow on the subject's surface, and the indication light shadow is used to indicate the coverage area of the X-ray emitted to each ionization chamber on the subject's surface.

[0106] The indication system is used, for example, after the subject is positioned and before the X-ray is emitted. The indication system can indicate the position of the X-ray emitted to the ionization chamber on the subject by means of visible light, which can be used as a basis for selecting the sampling ionization chamber, thereby facilitating more accurate selection of the sampling ionization chamber.

[0107] Figure 5 A schematic implementation scheme for illustrating the indication system is shown in FIG. Figure 5 As shown, the indication system includes a visible light generating module 10 and a light shielding module 30. Figure 1 , the visible light generation module 10 can emit a source light beam B projected to the subject's positioning space K, and the source light beam B is visible light. The visible light generation module 10 includes, for example, an LED lamp 11 and a reflector 12, but is not limited thereto. The shading module 30 is disposed on the optical path of the source light beam B before it reaches the subject's positioning space K, and can partially block the source light beam B to form an indication light beam P. This illustrative embodiment forms the indication light beam P through the source light beam B and the shading module 30, which is conducive to cost saving, but is not limited thereto.

[0108] In other exemplary embodiments, the indicator light beam P may be emitted by a combined light source, which is composed of several single light sources. The single light source is, for example, a point light source or a collimated light source. The indicator light beam P may be adjusted by adjusting the switches of the single light sources. In this way, the shading module may be omitted.

[0109] In this exemplary embodiment, the source light beam B in the subject placement space K is consistent with the optical path of the X-ray, that is, the source light beam B and the portion of the X-ray in the subject placement space K can be regarded as being emitted by a point light source located at the same position, thereby simplifying the setting of the light shielding module 30. Specifically, Figure 1As shown, in the present exemplary embodiment, the visible light emitted by the LED lamp 11 and the X-ray emitted by the X-ray tube 90 have the same optical path after the visible light is reflected by the mirror 12 and the X-ray passes through the mirror 12. By setting the mirror 12, the problem of position conflict between the LED lamp 11 and the X-ray tube 90 can be avoided. In other exemplary embodiments, the source beam B may also have a different optical path from that of the X-ray in the subject positioning space K.

[0110] Referring to Figure 1 , in the present exemplary embodiment, the light shielding module 30 is a light shielding plate perpendicular to the optical axis A of the source beam B. In the present exemplary embodiment, the source beam B and the X-ray beam are, for example, conical beams. Figure 1 , the part of the optical axis A of the source beam B below the mirror 12 overlaps with the X-ray optical axis. The light shielding plate has five fixed light shielding regions 31 ( Figure 1 the light shielding regions 31 are represented by the dark regions on the light shielding module 30 in Figure 1 ). Each fixed light shielding region 31 corresponds to an ionization chamber 80 (five ionization chambers 80 are taken as an example in the present exemplary embodiment). When the subject has not entered the subject positioning space K, each fixed light shielding region 31 can form a visible light shadow in the ionization chamber incident plane F for indicating the region corresponding to its corresponding ionization chamber 80 ( Figure 1 represented by the dark regions on the ionization chamber incident plane F in ). The structure of the light shielding module is simple, which is conducive to cost saving. In the exemplary embodiment, the light shielding plate is, for example, a glass plate coated with a light shielding coating in the fixed light shielding regions 31, but is not limited thereto.

[0111] In the present exemplary embodiment, five ionization chambers 80 are taken as an example, so five fixed light shielding regions 31 are correspondingly provided. In other exemplary embodiments, the number of the fixed light shielding regions 31 can be adjusted accordingly with the number of the ionization chambers 80.

[0112] Specifically, referring to Figure 5 , in the present exemplary embodiment, the light shielding plate serving as the light shielding module 30 can move relative to the visible light generating module 10 along the optical axis A of the source beam B. Referring to Figure 3 , the light shielding plate serving as the light shielding module 30 is arranged such that when the distance from the X-ray tube focal point P1 to the ionization chamber incident plane F is a standard distance, the light shielding plate located at the standard position can form a visible light shadow in the ionization chamber incident plane F that coincides with the boundaries of the ionization chambers 80 when the subject has not entered the subject positioning space. The "standard distance" is, for example, within the common distance range from the X-ray tube focal point to the ionization chamber incident plane, and can be specifically adjusted according to needs.

[0113] In the exemplary embodiment, the visible light generating module 10 and the light shielding module 30 are, for example, arranged in the housing of the collimator of the X-ray imaging system, and the indicating beam P is, for example, emitted through the light outlet of the collimator, but is not limited thereto.

[0114] As shown Figure 5 in the present illustrative embodiment, the indicating system further includes a driving module 50 and a control module 60. The driving module 50 is signal-connected to the control module 60. The driving module 50 can drive the light-shielding plate to move along the optical axis A of the source beam B. The driving module 50 is, for example, a motor, but is not limited thereto. In the illustrative embodiment, the indicating system further includes, for example, a transmission mechanism 40, and the driving module 50 drives the light-shielding plate to move through the transmission mechanism 40, for example. The transmission mechanism 40 includes, for example, a gear-rack transmission mechanism, a worm-gear transmission mechanism, or a belt transmission mechanism, etc., but is not limited thereto. The light-shielding plate is, for example, mounted on a sliding bracket and driven by the driving module 50. The driving module 50 and the control module 60 are, for example, also disposed within the housing of the beam expander, but are not limited thereto.

[0115] The control module 60 can calculate, according to formula (1), the target distance from the light-shielding plate of the light-shielding module 30 to the source beam focus P2, and can control the driving module 50 according to the target distance, so that the driving module 50 drives the light-shielding plate to move to meet the target distance.

[0116] SGD = SID*m / M Formula (1),

[0117] wherein, SGD is the target distance along the optical axis A of the source beam B from the source beam focus P2 to the light-shielding plate of the light-shielding module 30 (see Figure 3 , since in the present illustrative embodiment the source beam B coincides with the X-ray optical path within the subject positioning space K, so SGD is equal to the distance from the tube focus P1 to the light-shielding module 30), SID is the actual distance from the tube focus P1 to the ionization chamber entrance plane F, m is the overall width in the width direction W of all the fixed light-shielding regions 31, M is the overall width in the width direction W of all the ionization chambers 80, and the width direction W is parallel to the ionization chamber entrance plane F.

[0118] Thereby, when the distance from the tube focus P1 to the ionization chamber entrance plane F changes, it is only necessary to correspondingly adjust the position of the light-shielding module 30, and there is no need to replace the light-shielding module 30. Thereby, costs can be saved. It can be understood that the adjustment of the light-shielding module 30 on the basis of the standard position will partially lose the indication accuracy, but usually the change in the distance from the tube focus P1 to the ionization chamber entrance plane F is limited, and such a loss of accuracy is acceptable. In use, the position of the light-shielding module 30 only needs to be adjusted according to the distance from the tube focus P1 to the ionization chamber entrance plane F, and there is no need to adjust according to different subjects, which is the benefit brought by the fact that the source beam B coincides with the X-ray optical path within the subject positioning space K, for example.

[0119] Automatic adjustment can be achieved by setting the driving module 50 and the control module 60, but it is not limited thereto. In other illustrative embodiments, the driving module 50 and the control module 60 may not be provided, and instead, after the user calculates according to formula (1), the position of the light-shielding module is adjusted manually.

[0120] In other illustrative embodiments, when the distance from the tube focus P1 to the incident plane F of the ionization chamber is fixed, the light-shielding module 30 only needs to be set to: when the subject has not entered the subject positioning space, a visible light shadow that coincides with the boundary of each ionization chamber can be formed on the incident plane F of the ionization chamber, and its position remains fixed.

[0121] In other illustrative embodiments, the source beam is, for example, inconsistent with the X-ray optical path in the subject positioning space. In this case, the following adjustments can be made. The light-shielding module 30 can be translated relative to the visible light generation module 10 (the direction is not limited). The light-shielding module 30 is set such that when the distance from the tube focus P1 to the incident plane F of the ionization chamber is a standard distance, the light-shielding module 30 at the standard position can form a visible light shadow that coincides with the boundary of each ionization chamber 80 on the incident plane F of the ionization chamber. The driving module 50 can drive the light-shielding module 30 to translate (the direction is not limited). The control module 60 can obtain the maximum distance from the subject's surface to the incident plane of the ionization chamber, and control the driving module 50 according to this maximum distance to adjust the spatial position of the light-shielding module, so that the indicating light and shadow can indicate the coverage area of the X-ray beam incident on each ionization chamber on the subject's surface. Thereby, the position setting of the source beam can be made more flexible. The maximum distance from the subject's surface to the incident plane of the ionization chamber can be obtained, for example, by a camera, TOF, radar, etc. through recognition and measurement, or can be obtained by estimating the body thickness based on the subject's height and weight.

[0122] The control module 60 controls the driving module 50 to adjust the spatial position of the light-shielding module according to the maximum distance from the subject's surface to the incident plane of the ionization chamber, so that the indicating light and shadow can indicate the coverage area of the X-ray beam incident on each ionization chamber on the subject's surface. Specifically: according to the maximum distance from the subject's surface to the incident plane of the ionization chamber and the distance from the tube focus to the incident plane of the ionization chamber, the spatial position of the light-shielding module is calculated by looking up a table. Since the positions of the tube focus and the source beam focus are both known and determined, they project X-rays and visible light to the ionization chamber at different positions respectively. In this way, when the position of the subject's surface is known, the specific position of the light-shielding module can be determined. The relationship between this position and the maximum distance from the subject's surface to the incident plane of the ionization chamber and the distance from the tube focus to the incident plane of the ionization chamber can be pre-recorded. In this way, the spatial position of the light-shielding module can be quickly obtained by looking up the table. In this embodiment, the translation of the light-shielding module is not only along the optical axis direction, but also includes the direction perpendicular to the optical axis, and this direction perpendicular to the optical axis is generally the connection line between the tube focus and the LED lamp.

[0123] As shown Figure 5 in the schematic embodiment, the indication system further includes a sensor 70, which is signal-connected to the control module 60. The sensor 70 is used to sense the indication light and shadow formed on the surface of the subject. In the schematic embodiment, the sensor 70 is, for example, a camera, but is not limited thereto. The control module 60 can, for each ionization chamber 80, according to the sensing result of the sensor 70, analyze the proportion of the projection area of the part corresponding to the ionization chamber in the indication light and shadow along the X-ray irradiation direction on the ionization chamber incident plane, in the area of the ionization chamber on the ionization chamber incident plane, and then select the sampling ionization chamber according to the analysis result. This facilitates the automatic selection of the sampling ionization chamber. In the schematic embodiment, the control module 60 analyzes the above proportion through artificial intelligence technology, for example.

[0124] In the schematic embodiment, the control module 60 is, for example, set as follows:

[0125] If there are ionization chambers with a proportion of 100%, all the ionization chambers with a proportion of 100% are selected as sampling ionization chambers, but are not limited thereto. In other schematic embodiments, it may also be that if there are ionization chambers with a proportion of 100%, among the ionization chambers with a proportion of 100%, the ionization chamber farthest from the edge of the projection of the subject along the X-ray propagation direction on the ionization chamber incident plane is selected as the sampling ionization chamber, which is beneficial to improving the X-ray imaging quality;

[0126] If the highest value of the proportion of each ionization chamber is lower than 100% and greater than or equal to a set threshold, the sampling ionization chamber is selected according to the value of the proportion and the dose threshold of the sampling ionization chamber in the automatic exposure control system is adjusted. Specifically, as described above, it will not be elaborated here. The set threshold is set according to experience, for example, which can reduce the probability of the subject repositioning and improve the comfort of the subject during the examination;

[0127] If the proportion of each ionization chamber is less than the set threshold, the subject is prompted to reposition. In other schematic embodiments, it may also be that if there are no ionization chambers with a proportion of 100%, the subject is prompted to reposition.

[0128] The present invention also provides an X-ray imaging system, which includes the above indication system. The indication system is used, for example, after the subject positioning is completed and before the X-ray is emitted. The indication system can indicate the position of the X-ray directed at the ionization chamber on the subject in a visible light manner, and this is used as the basis for selecting the sampling ionization chamber, which is beneficial to more accurately selecting the sampling ionization chamber.

[0129] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0130] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent implementation or change made without departing from the technical spirit of the present invention, such as the combination, division or repetition of features, should be included in the protection scope of the present invention.

Claims

1. An indicating method for indicating the position of X-rays irradiated onto an ionization chamber on a subject, characterized in that, Including: Emitting an indicating light beam that can propagate within the positioning space of the subject, the indicating light beam being visible light, and the indicating light beam being arranged to be able to form an indicating light and shadow on the surface of the subject, the indicating light and shadow being used to indicate the coverage area of the X-ray directed at each ionization chamber on the surface of the subject; The indicating method further includes: selecting a sampling ionization chamber according to the indicating light and shadow formed on the surface of the subject. Specifically, for each ionization chamber, according to the indicating light and shadow formed on the surface of the subject, the projection area of the part of the indicating light and shadow corresponding to this ionization chamber along the X-ray irradiation direction on the incident plane of the ionization chamber is analyzed, and the ratio of the projection area to the area of the ionization chamber on the incident plane of the ionization chamber is obtained, and then the sampling ionization chamber is selected according to the analysis result; Among them, selecting the sampling ionization chamber according to the analysis result specifically includes: among the ionization chambers with the ratio of 100%, the ionization chamber farthest from the edge of the projection of the subject along the X-ray propagation direction on the incident plane of the ionization chamber is selected as the sampling ionization chamber; If the highest value of the ratio of each ionization chamber is lower than 100% and greater than or equal to a set threshold, then select the sampling ionization chamber according to the value of the ratio and adjust the dose threshold of the sampling ionization chamber in the automatic exposure control system; If the ratio of each ionization chamber is less than a set threshold, then prompt the subject to reposition; Among them, if the highest value of the ratio of each ionization chamber is lower than 100% and greater than or equal to a set threshold, then selecting the sampling ionization chamber according to the value of the ratio and adjusting the dose threshold of the sampling ionization chamber in the automatic exposure control system specifically includes: If the highest value of the ratio of each ionization chamber is lower than 100% and greater than or equal to the first value, then the ionization chamber with the highest ratio is used as the sampling ionization chamber, and the look-up table is queried according to the highest value of the ratio; if there is a corresponding query ratio value in the look-up table, then a unique query coefficient is obtained and used as the calculation coefficient of the sampling ionization chamber; if there is no corresponding query ratio value in the look-up table, then look up the table according to the two query ratio values closest to the ratio, obtain two query coefficients, and then calculate the coefficient corresponding to the ratio by interpolation method and use it as the calculation coefficient of the sampling ionization chamber; If the highest value of the ratio of each ionization chamber is lower than the first value and greater than or equal to the second value, and the ratio of at least two ionization chambers is less than the first value and greater than or equal to the second value, then the ionization chambers with the ratio less than the first value and greater than or equal to the second value are used as sampling ionization chambers. For each ionization chamber used as a sampling ionization chamber, the coefficient corresponding to each ionization chamber is obtained according to the method of the look-up table, and the mean value of these coefficients is calculated and used as the calculation coefficient of the sampling ionization chamber; Among them, in the look-up table, according to the query ratio value, the corresponding body part and the subject thickness data, the corresponding query coefficient is found.

2. The indication method according to claim 1, wherein Including: Emitting a source light beam directed at the positioning space of the subject, the source light beam being visible light, and a light-shielding module being arranged on the light path before the source light beam reaches the positioning space of the subject, the light-shielding module being able to partially block the source light beam to form the indicating light beam.

3. The indication method according to claim 2, characterized in that, The source beam is aligned with the optical path of the X-ray within the subject positioning space.

4. The indication method according to claim 3, characterized in that, The light shielding module is a light shielding plate perpendicular to the optical axis of the source beam. The light shielding plate has several fixed light shielding regions, each of the fixed light shielding regions corresponding to one of the ionization chambers, and each of the fixed light shielding regions being capable of forming a visible light shadow in the ionization chamber incident plane for indicating the region of its corresponding ionization chamber.

5. The indication method according to claim 4, characterized in that Arranging the light shielding module on the optical path before the source beam reaches the subject positioning space specifically includes: On the optical path before the source beam reaches the subject positioning space, arranging the light shielding plate capable of moving along the optical axis of the source beam, the light shielding plate being arranged such that when the distance from the tube focus to the ionization chamber incident plane is a standard distance, the light shielding plate at the standard position can form a visible light shadow coinciding with the boundaries of each of the ionization chambers in the ionization chamber incident plane; and Calculating the target distance from the light shielding plate to the source beam focus according to formula (1), and adjusting the position of the light shielding plate along the optical axis of the source beam according to the target distance to meet the target distance, SGD = SID*m / M formula (1), where SGD is the target distance from the source beam focus to the light shielding plate, SID is the actual distance from the tube focus to the ionization chamber incident plane, m is the overall width of all the fixed light shielding regions, and M is the overall width of all the ionization chambers.

6. The indication method according to claim 2, wherein, Arranging the light shielding module on the optical path before the source beam reaches the subject positioning space specifically includes: On the optical path before the source beam reaches the subject positioning space, arranging the translatable light shielding module, the light shielding module being arranged such that when the distance from the tube focus to the ionization chamber incident plane is a standard distance, the light shielding module at the standard position can form a visible light shadow coinciding with the boundaries of each of the ionization chambers in the ionization chamber incident plane; Obtaining the maximum distance from the subject surface to the ionization chamber incident plane; and Adjusting the spatial position of the light shielding module according to the maximum distance so that the indicated light and shadow can indicate the coverage area of the X-ray irradiating each ionization chamber on the subject surface.

7. The indication method according to claim 1, characterized in that, Selecting the sampling ionization chamber according to the indicated light and shadow formed on the subject surface, specifically: sensing the indicated light and shadow formed on the subject surface through a sensor. For each ionization chamber, according to the sensing result of the sensor, analyzing the proportion of the projection area of the part of the indicated light and shadow corresponding to the ionization chamber along the X-ray irradiation direction in the ionization chamber incident plane to the area of the ionization chamber in the ionization chamber incident plane, and then selecting the sampling ionization chamber according to the analysis result.

8. An indication system for indicating the position of X-rays irradiated onto an ionization chamber on a subject, characterized in that, The indicating system can emit an indicating beam (P) propagating within the subject positioning space. The indicating beam (P) is visible light, and the indicating beam (P) can form an indicated light and shadow on the subject surface, and the indicated light and shadow is used to indicate the coverage area of the X-ray irradiating each ionization chamber on the subject surface; The indication system further comprises a sensor (70), wherein the sensor (70) is used to sense the indication light and shadow formed on the surface of the subject, and the control module (60) is capable of analyzing, for each of the ionization chambers (80), according to the sensing result of the sensor (70), obtaining the proportion of the projection area of the portion of the indication light and shadow corresponding to the ionization chamber along the X-ray irradiation direction on the incident plane of the ionization chamber, and then selecting a sampling ionization chamber according to the analysis result; The control module (60) is configured to: Among the ionization chambers with the ratio of 100%, the ionization chamber farthest from the edge of the projection of the subject along the X-ray propagation direction on the incident plane of the ionization chamber is selected as the sampling ionization chamber; If the highest value of the ratio of each of the ionization chambers is lower than 100% and greater than or equal to a set threshold, a sampling ionization chamber is selected according to the value of the ratio and a dose threshold of the sampling ionization chamber in an automatic exposure control system is adjusted; If the ratios of the ionization chambers are all less than a set threshold, the subject is prompted to reposition; Wherein, if the highest value of the ratio of each ionization chamber is lower than 100% and greater than or equal to a set threshold, selecting a sampling ionization chamber according to the value of the ratio and adjusting the dose threshold of the sampling ionization chamber in the automatic exposure control system specifically includes: If the highest value of the ratio of each ionization chamber is lower than 100% and greater than or equal to the first value, the ionization chamber with the highest ratio is used as the sampling ionization chamber, and the query table is queried according to the highest value of the ratio; if there is a corresponding query ratio value in the query table, a unique query coefficient is obtained, which is used as the calculation coefficient of the sampling ionization chamber; if there is no corresponding query ratio value in the query table, the table is looked up according to the two query ratio values closest to the ratio to obtain two query coefficients, and then the coefficient corresponding to the ratio is calculated by interpolation method, and it is used as the calculation coefficient of the sampling ionization chamber; If the highest value of the ratio of each ionization chamber is lower than the first value and greater than or equal to the second value, and the ratio of at least two ionization chambers is lower than the first value and greater than or equal to the second value, then the ionization chamber whose ratio is lower than the first value and greater than or equal to the second value is used as the sampling ionization chamber, and for each ionization chamber used as the sampling ionization chamber, the coefficient corresponding to each ionization chamber is obtained according to the method of the query table, and the average of these coefficients is calculated and used as the calculation coefficient of the sampling ionization chamber; Wherein, in the query table, the corresponding query coefficient is found according to the query ratio value, the corresponding body part and the thickness data of the subject.

9. The indication system according to claim 8, wherein, The indication system comprises: A visible light generating module (10) capable of emitting a source light beam (B) projected toward the subject positioning space, wherein the source light beam (B) is visible light; and A light shielding module (30) is arranged on the optical path of the source light beam (B) before it reaches the subject positioning space (K), and is capable of partially shielding the source light beam (B) to form the indication light beam (P).

10. The indication system according to claim 9, wherein The source light beam (B) is consistent with the optical path of the X-ray in the subject positioning space.

11. The indicating system according to claim 10, characterized in that, The light-shielding module (30) is a light-shielding plate perpendicular to the optical axis (A) of the source beam (B). The light-shielding plate has several fixed light-shielding areas (31), and each of the fixed light-shielding areas (31) corresponds to an ionization chamber (80). Each of the fixed light-shielding areas (31) can form a visible light shadow in the ionization chamber incident plane (F) to indicate the area of its corresponding ionization chamber (80).

12. The indicating system according to claim 11, wherein, The light-shielding plate can move along the optical axis (A) of the source beam (B) relative to the visible light generating module (10). The light-shielding plate is arranged such that when the distance from the tube focus (P1) to the ionization chamber incident plane (F) is a standard distance, the light-shielding plate at the standard position can form a visible light shadow in the ionization chamber incident plane (F) that coincides with the boundaries of each ionization chamber (80).

13. The indicating system according to claim 12, wherein The indicating system further includes: A driving module (50) capable of driving the light-shielding plate to move along the optical axis (A) of the source beam (B); wherein: The control module (60) can calculate the target distance from the light-shielding plate to the source beam focus (P2) according to formula (1), and can control the driving module (50) according to the target distance to make the driving module (50) drive the light-shielding plate to move to meet the target distance. SGD = SID*m / M Formula (1), wherein SGD is the target distance from the source beam focus (P2) to the light-shielding plate, SID is the actual distance from the tube focus (P1) to the ionization chamber incident plane (F), m is the overall width of all the fixed light-shielding areas (31), and M is the overall width of all the ionization chambers (80).

14. The indication system according to claim 9, characterized in that, The light-shielding module (30) can be translated relative to the visible light generating module (10). The light-shielding module (30) is arranged such that when the distance from the tube focus (P1) to the ionization chamber incident plane (F) is a standard distance, the light-shielding module (30) at the standard position can form a visible light shadow in the ionization chamber incident plane (F) that coincides with the boundaries of each ionization chamber (80); the indicating system further includes: A driving module (50) capable of driving the light-shielding module (30) to translate; wherein The control module (60) can obtain the maximum distance from the surface of the subject to the ionization chamber incident plane, and control the driving module (50) according to this maximum distance to adjust the spatial position of the light-shielding module, so that the indicating light and shadow can indicate the coverage area of the X-rays incident on each ionization chamber on the surface of the subject.

15. An X-ray imaging system, characterized in that, Including the indicating system according to any one of claims 9 to 14.

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