Digital subtraction method and device for X-ray photography, control host and medium

Abstract

The embodiment of the invention discloses a digital subtraction method and device for X-ray photography, a control host and a medium. The method comprises the steps that a mask image and a perspective image are obtained, the current-time product in the exposure process of the perspective image is different from the current-time product in the exposure process of the mask image, and the tube voltage in the exposure process of the perspective image is equal to the tube voltage in the exposure process of the mask image; determining a correction factor of the perspective image; correcting the perspective image based on the correction factor; and determining a digital subtraction image based on the mask image and the corrected perspective image. And for the perspective image of which the current-time product in the exposure process is different from the current-time product in the exposure process of the mask image, digital subtraction is performed on the perspective image and the mask image after correction is performed, so that the quality of the subtraction image is improved, and the problem of artifacts can be reduced or overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, in particular to a digital subtraction method, device, control host and medium for X-ray photography. Background Art

[0002] An X-ray photography system generally includes an X-ray generating component, a chest radiograph stand (Bucky-wall-stand, BWS) component, an examination table (table) component, a flat panel detector, and a control host located remotely, etc. The X-ray generating component emits X-rays that penetrate the irradiated object by using the high voltage provided by a high-voltage generator, and forms medical image information of the irradiated object on the flat panel detector. The flat panel detector sends the medical image information to the control host, and the control host generates a medical image. The irradiated object can stand near the chest radiograph stand component or lie on the examination table component, so as to respectively receive X-ray photography of various parts.

[0003] Digital Subtracted Angiography (DSA) technology is a fluoroscopy technology widely used in interventional radiology to display blood vessels. Structures that are opaque to X-rays, such as bones, are digitally removed ("subtracted") from the image, so that blood vessels can be accurately depicted. DSA generally includes three stages. Stage (1): generating a mask image (usually without using a contrast agent); Stage (2): generating a fluoroscopy image (usually using a contrast agent); Stage (3): subtracting the mask image from the fluoroscopy image to obtain a subtracted image.

[0004] How to improve the quality of the subtracted image is one of the key concerns in the industry currently. Summary of the Invention

[0005] Embodiments of the present invention provide a digital subtraction method, device, control host and medium for X-ray photography.

[0006] A digital subtraction method for X-ray photography includes:

[0007] Obtaining a mask image and a fluoroscopy image, wherein the current-time product during the exposure process of the fluoroscopy image is different from the current-time product during the exposure process of the mask image, and the tube voltage during the exposure process of the fluoroscopy image is equal to the tube voltage during the exposure process of the mask image;

[0008] Determining a correction factor for the fluoroscopy image;

[0009] Correcting the fluoroscopy image based on the correction factor;

[0010] Determining a digital subtracted image based on the mask image and the corrected fluoroscopy image.

[0011] Therefore, for a fluoroscopic image in which the current-time product during the exposure process is different from that during the exposure process of the mask image, after correction, digital subtraction is performed with the mask image, improving the quality of the subtracted image and reducing or overcoming the artifact problem.

[0012] In one embodiment, the tube current during the exposure process of the fluoroscopic image is equal to the tube current during the exposure process of the mask image, and the first exposure time during the exposure process of the fluoroscopic image is different from the second exposure time during the exposure process of the mask image;

[0013] The method includes: determining the first exposure time and the second exposure time;

[0014] Determining the correction factor for the fluoroscopic image includes: determining the correction factor based on the proportional relationship between the first exposure time and the second exposure time.

[0015] Therefore, for a scenario where the tube current remains unchanged and the exposure time changes in the pulse mode, correction is performed based on the proportional relationship between the first exposure time and the second exposure time to achieve fast correction.

[0016] In one embodiment, the exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the first tube current during the exposure process of the fluoroscopic image is different from the second tube current during the exposure process of the mask image; the method includes:

[0017] Determining the first tube current and the second tube current;

[0018] Determining the correction factor for the fluoroscopic image includes:

[0019] Determining the correction factor based on the proportional relationship between the first tube current and the second tube current.

[0020] Therefore, for a scenario where the exposure time remains unchanged and the tube current changes in the pulse mode, correction can be performed based on the proportional relationship between the first tube current and the second tube current to achieve fast correction.

[0021] In one embodiment, the exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the first tube current during the exposure process of the fluoroscopic image is different from the second tube current during the exposure process of the mask image; the method includes:

[0022] Determining the second tube current and the exposure moment of the fluoroscopic image;

[0023] Determining the correction factor for the fluoroscopic image includes:

[0024] Determine the mapping relationship between the tube current and the exposure time within the transitional change section of the tube current during the exposure process of the perspective image;

[0025] Based on the mapping relationship and the exposure time of the perspective image, determine the first tube current;

[0026] Based on the proportional relationship between the first tube current and the second tube current, determine the correction factor.

[0027] Therefore, for the scenario where the exposure time remains unchanged and the tube current changes in the continuous mode, the first tube current within the transitional change section is determined based on the mapping relationship between the tube current and the exposure time, and then the perspective image is corrected based on the proportional relationship between the first tube current and the second tube current. Therefore, the section where the tube current undergoes transitional changes is considered, improving the quality of the subtracted image.

[0028] In one embodiment, the method includes:

[0029] Determine the mapping relationship in an interpolation manner, where the mapping relationship includes a linear mapping relationship or a non-linear mapping relationship;

[0030] The non-linear mapping relationship includes at least one of the following:

[0031] Exponential function; power function; logarithmic function; polynomial function.

[0032] Therefore, the mapping relationship can be interpolated through various functions. Among them, the linear mapping relationship has the advantage of fast operation, and the non-linear mapping relationship has the advantage of accurate fitting.

[0033] In one embodiment, the method includes:

[0034] Determine the current-time product during the exposure process of the perspective image and the current-time product during the exposure process of the mask image;

[0035] The determination of the correction factor for the perspective image includes:

[0036] Based on the proportional relationship between the current-time product during the exposure process of the perspective image and the current-time product during the exposure process of the mask image, determine the correction factor.

[0037] Therefore, for the scenario where the exposure time changes and the tube current changes in the pulse mode, the perspective image is corrected based on the proportional relationship between the current-time products, improving the correction speed.

[0038] A digital subtraction device for X-ray photography, including;

[0039] An acquisition module, configured to acquire a mask image and a fluoroscopic image, wherein the current-time product during the exposure process of the fluoroscopic image is different from the current-time product during the exposure process of the mask image, and the tube voltage during the exposure process of the fluoroscopic image is equal to the tube voltage during the exposure process of the mask image;

[0040] A first determination module, configured to determine a correction factor for the fluoroscopic image;

[0041] A correction module, configured to correct the fluoroscopic image based on the correction factor;

[0042] A second determination module, configured to determine a digital subtraction image based on the mask image and the corrected fluoroscopic image.

[0043] Therefore, for a fluoroscopic image whose current-time product during the exposure process is different from that of the mask image, after correction and then performing digital subtraction with the mask image, the quality of the subtracted image is improved, and the artifact problem can be reduced or overcome.

[0044] In one embodiment, the tube current during the exposure process of the fluoroscopic image is equal to the tube current during the exposure process of the mask image, and the first exposure time during the exposure process of the fluoroscopic image is different from the second exposure time during the exposure process of the mask image;

[0045] The acquisition module is configured to determine the first exposure time and the second exposure time;

[0046] The first determination module is configured to determine the correction factor based on the proportional relationship between the first exposure time and the second exposure time.

[0047] Therefore, for a scenario where the tube current remains unchanged and the exposure time changes in the pulse mode, correction is performed based on the proportional relationship between the first exposure time and the second exposure time to achieve fast correction.

[0048] In one embodiment, the exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the first tube current during the exposure process of the fluoroscopic image is different from the second tube current during the exposure process of the mask image;

[0049] The acquisition module is configured to determine the first tube current and the second tube current;

[0050] The first determination module is configured to determine the correction factor based on the proportional relationship between the first tube current and the second tube current.

[0051] Therefore, for a scenario where the exposure time remains unchanged while the tube current changes in the pulse mode, correction is performed based on the proportional relationship between the first tube current and the second tube current to achieve fast correction.

[0052] In one embodiment, the exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the first tube current during the exposure process of the fluoroscopic image is different from the second tube current during the exposure process of the mask image;

[0053] The acquisition module is configured to determine the second tube current and the exposure moment of the fluoroscopic image;

[0054] The first determination module is configured to determine the mapping relationship between the tube current and the exposure moment within the transition change section of the tube current during the exposure process of the fluoroscopic image; based on the mapping relationship and the exposure moment of the fluoroscopic image, determine the first tube current; and based on the proportional relationship between the first tube current and the second tube current, determine the correction factor.

[0055] Therefore, for a scenario where the exposure time remains unchanged while the tube current changes in the continuous mode, the first tube current within the transition change section is determined based on the mapping relationship between the tube current and the exposure moment, and then the fluoroscopic image is corrected based on the proportional relationship between the first tube current and the second tube current. Therefore, the section where the tube current undergoes a transition change is considered, improving the quality of the subtracted image.

[0056] In one embodiment, the acquisition module is configured to determine the current-time product during the exposure process of the fluoroscopic image and the current-time product during the exposure process of the mask image;

[0057] The first determination module is configured to determine the correction factor based on the proportional relationship between the current-time product during the exposure process of the fluoroscopic image and the current-time product during the exposure process of the mask image.

[0058] Therefore, for a scenario where the exposure time changes and the tube current changes in the pulse mode, the fluoroscopic image is directly corrected based on the proportional relationship between the current-time products, improving the correction speed.

[0059] A control host of an X-ray imaging system includes:

[0060] A processor;

[0061] A memory for storing executable instructions of the processor;

[0062] The processor is configured to read the executable instructions from the memory and execute the executable instructions to implement the digital subtraction method for X-ray imaging as described above.

[0063] A computer-readable storage medium, on which computer instructions are stored, and when the computer instructions are executed by a processor, the digital subtraction method of X-ray imaging as described above is implemented. Description of the Drawings

[0064] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that those of ordinary skill in the art can more clearly understand the above and other features and advantages of the present invention. In the drawings:

[0065] Figure 1 is a schematic flowchart of the digital subtraction method of X-ray imaging according to an embodiment of the present invention.

[0066] Figure 2 is a schematic diagram of the mapping relationship between tube current and exposure time when the tube current changes in the continuous mode according to an embodiment of the present invention.

[0067] Figure 3 is a schematic diagram when the current-time product changes in the pulse mode according to an embodiment of the present invention.

[0068] Figure 4 is a schematic diagram of the peak opacity (PCOP) image generated based on the subtracted image according to an embodiment of the present invention.

[0069] Figure 5 is a comparison chart of PCOP images using different correction methods according to an embodiment of the present invention.

[0070] Figure 6 is a comparison chart of the effects using different correction methods according to an embodiment of the present invention.

[0071] Figure 7 is a schematic structural diagram of the digital subtraction device for X-ray imaging according to an embodiment of the present invention.

[0072] Figure 8 is a schematic structural diagram of the control host of the X-ray imaging system according to an embodiment of the present invention.

[0073] Among them, the reference numerals are as follows: Detailed Embodiments

[0074] To make the objectives, technical solutions and advantages of the present invention clearer, the following examples are given to further elaborate on the present invention. In this patent application, nouns and pronouns related to people are not limited to specific genders.

[0075] For the sake of simplicity and intuitiveness in description, the solutions of the present invention will be elaborated below by describing several representative embodiments. A large number of details in the embodiments are only used to help understand the solutions of the present invention. However, it is obvious that the technical solutions of the present invention can be implemented without being limited to these details. In order to avoid unnecessarily obscuring the solutions of the present invention, some embodiments are not described in detail, but only the framework is given. Hereinafter, "including" means "including but not limited to", and "according to..." means "at least according to..., but not limited to only according to...". Due to the language habits of Chinese, when the quantity of a component is not specifically indicated hereinafter, it means that the component can be one or more, or can be understood as at least one.

[0076] After observation, the applicant found the following phenomenon: During the exposure process, the X-ray tube may reduce the tube current or reduce the exposure time based on considerations such as heat protection to achieve a higher temporal resolution. Therefore, the current-time product (i.e., the product of the exposure time and the tube current) in the respective exposure processes of stage (2) for generating a fluoroscopic image and stage (1) for generating a mask image in digital subtraction may change, resulting in artifacts in the subtracted image. The applicant also found that for a fluoroscopic image whose current-time product during the exposure process is different from that of the mask image during the exposure process, the fluoroscopic image can be corrected and then subjected to digital subtraction with the mask image, thereby improving the quality of the subtracted image and reducing or overcoming the artifact problem.

[0077] The above disclosure details the technical defects existing in the prior art, the reasons for these technical defects, and the thinking and analysis process for overcoming these technical defects. In fact, the recognition of the above technical defects is not common knowledge in the art, but a novel discovery by the applicant in the research. In addition, the tracing of the reasons for the technical defects and the thinking and analysis process for overcoming the technical defects are also the gradual analysis results of the applicant in the actual research process, and are not common knowledge in the art.

[0078] Figure 1 is a schematic flowchart of a digital subtraction method for X-ray photography according to an embodiment of the present invention. Figure 1 The shown process can be executed by the control host of an X-ray photography system (such as various X-ray medical imaging systems). Or, Figure 1 The shown process can be executed by any electronic device with computing capabilities.

[0079] As Figure 1 shown, the method includes:

[0080] Step 101: Obtain a mask image and a fluoroscopic image. The charge-time product during the exposure process of the fluoroscopic image is different from the charge-time product during the exposure process of the mask image, and the tube voltage during the exposure process of the fluoroscopic image is equal to the tube voltage during the exposure process of the mask image.

[0081] The working modes of the X-ray tube assembly usually include a pulse mode and a continuous mode. In the continuous mode, the X-ray tube assembly emits a continuous X-ray beam; in the pulse mode, the X-ray beam emitted by the X-ray tube assembly is a series of short pulses, rather than continuously emitting an X-ray beam. During the exposure process of generating a mask image, a contrast agent is usually not used. During the exposure process of generating a fluoroscopic image, a contrast agent is usually used. Among them: the number of fluoroscopic images can be one or more.

[0082] Here, the specific scenarios where the charge-time product during the exposure process of the fluoroscopic image is different from the charge-time product during the exposure process of the mask image can include:

[0083] Scenario (1): The tube current during the exposure process of the fluoroscopic image is equal to the tube current during the exposure process of the mask image, while the exposure time during the exposure process of the fluoroscopic image is different from the exposure time during the exposure process of the mask image, and the charge-time product during the exposure process of the fluoroscopic image is different from the charge-time product during the exposure process of the mask image. Scenario (1) usually occurs in the pulse mode.

[0084] Scenario (2): The tube current during the exposure process of the fluoroscopic image is different from the tube current during the exposure process of the mask image, while the exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the charge-time product during the exposure process of the fluoroscopic image is different from the charge-time product during the exposure process of the mask image. Scenario (2) can occur in both the continuous mode and the pulse mode. For scenario (2): When the X-ray tube assembly operates in the pulse mode, if the X-ray assembly itself uses pulse time adjustment to compensate for the current to ensure that the charge-time product changes instantaneously, a transition change section of the tube current is usually not required. When the X-ray tube assembly operates in the continuous mode, the change of the tube current is usually not completed instantaneously, and there is usually a transition change section of the tube current.

[0085] Scenario (3): The tube current during the exposure process of the fluoroscopic image is different from the tube current during the exposure process of the mask image, and the exposure time during the exposure process of the fluoroscopic image is also different from the exposure time during the exposure process of the mask image, and the charge-time product during the exposure process of the fluoroscopic image is different from the charge-time product during the exposure process of the mask image. Scenario (3) usually occurs in the pulse mode.

[0086] Step 102: Determine the correction factor of the fluoroscopic image.

[0087] Step 103: Correct the perspective image based on the correction factor.

[0088] Step 104: Determine the digital subtraction image based on the mask image and the corrected perspective image.

[0089] For example, assume the mask image is A; the corrected perspective image is B. The digital subtraction image is: ln(B) - ln(A); where ln() is the logarithmic function with the natural constant e as the base.

[0090] In one embodiment, corresponding to the above scenario (1): the tube current during the exposure of the perspective image is equal to the tube current during the exposure of the mask image, and the first exposure time during the exposure of the perspective image is different from the second exposure time during the exposure of the mask image; the method includes: determining the first exposure time and the second exposure time (for example, via the communication cable between the X-ray tube assembly and the control host); Step 102 specifically includes: determining the correction factor based on the proportional relationship between the first exposure time and the second exposure time.

[0091] In one embodiment, determining the first exposure time and the second exposure time may include: receiving the first exposure time and the second exposure time from the X-ray tube assembly via the communication cable between the control host and the X-ray tube assembly. The proportional relationship between the first exposure time and the second exposure time may include: (1) the quotient of the first exposure time and the second exposure time; (2) various variation values based on the quotient of the first exposure time and the second exposure time (for example, multiplying or dividing the quotient by a predetermined coefficient). Step 103 may include: dividing the perspective image by the correction factor to obtain the corrected perspective image. Wherein, the specific meaning of dividing the perspective image by the correction factor includes: dividing the gray value of each pixel point in the perspective image by the correction factor.

[0092] Example: Assume the mask image is I m ; r1 is the correction factor, r1 = ms n / ms0; where ms0 is the first pulse width time during the exposure of the mask image, that is, the second exposure time during the exposure of the mask image; ms n is the second pulse width time during the exposure of the perspective image, that is, the first exposure time during the exposure of the perspective image; the perspective image before correction is I n ; the corrected perspective image is I n / r1;

[0093] Then: The subtraction image DSA image can be determined based on formula (1) n .

[0094]

[0095] Wherein: when the exposure time of the fluoroscopic image does not change (the exposure time of the fluoroscopic image remains the first pulse width time ms0), based on the mask image I m and the fluoroscopic image I before correction n generate a DSA image n ; when the exposure time of the fluoroscopic image changes (from the first pulse width time ms0 to the second pulse width time ms n ), based on the mask image I m and the corrected fluoroscopic image (ln(I n / r1)) generate a DSA image n , where r1 = ms n / ms0.

[0096] Therefore, for the scenario where the tube current remains unchanged and the pulse width changes in the pulse mode, correction can be performed based on the proportional relationship between the first exposure time and the second exposure time, achieving fast correction.

[0097] In one embodiment, corresponding to the above scenario (2), the X-ray tube assembly operates in the pulse mode: the exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the first tube current during the exposure process of the fluoroscopic image is different from the second tube current during the exposure process of the mask image; the method includes: determining (for example, via the communication cable between the X-ray tube assembly and the control host) the first tube current and the second tube current; step 102 specifically includes: determining a correction factor based on the proportional relationship between the first tube current and the second tube current.

[0098] In one embodiment, determining the first tube current and the second tube current may include: receiving the first tube current and the second tube current from the X-ray tube assembly via the communication cable between the control host and the X-ray tube assembly. The proportional relationship between the first tube current and the second tube current may include: (1) the quotient of the first tube current and the second tube current;

[0099] (2) various variation values based on the quotient of the first tube current and the second tube current (for example, multiplying or dividing the quotient by a predetermined coefficient). Step 103 may include: dividing the fluoroscopic image by the correction factor to obtain the corrected fluoroscopic image. Wherein, the specific meaning of dividing the fluoroscopic image by the correction factor includes: dividing the gray value of each pixel point in the fluoroscopic image by the correction factor.

[0100] Therefore, for the scenario where the exposure time remains unchanged and the tube current changes in the pulse mode, correction can be performed based on the proportional relationship between the first tube current and the second tube current, achieving fast correction.

[0101] In one embodiment, corresponding to the above scenario (2), the X-ray tube assembly operates in a continuous mode: the exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the first tube current during the exposure process of the fluoroscopic image is different from the second tube current during the exposure process of the mask image; the method includes: determining (for example, via a communication cable between the X-ray tube assembly and the control host) the second tube current and the exposure moment of the fluoroscopic image; step 102 specifically includes: determining the mapping relationship between the tube current and the exposure moment within the transition change section of the tube current during the exposure process of the fluoroscopic image; based on the mapping relationship and the exposure moment of the fluoroscopic image, determining the first tube current; determining the corresponding relationship between the first tube current and the second tube current as the correction factor. Specifically, determining the second tube current and the exposure moment of the fluoroscopic image may include: receiving the second tube current and the exposure moment of the fluoroscopic image from the X-ray tube assembly via a communication cable between the control host and the X-ray tube assembly. The proportional relationship between the first tube current and the second tube current may include: (1) the quotient of the first tube current and the second tube current; (2) various variation values based on the quotient of the first tube current and the second tube current (for example, multiplying or dividing the quotient by a predetermined coefficient). Step 103 may include: dividing the fluoroscopic image by the correction factor to obtain a corrected fluoroscopic image. Herein, dividing the fluoroscopic image by the correction factor specifically means: dividing the gray value of each pixel point in the fluoroscopic image by the correction factor.

[0102] Therefore, for the scenario where the exposure time remains unchanged and the tube current changes in the continuous mode, the first tube current within the transition change section is determined based on the mapping relationship between the tube current and the exposure moment, and then the fluoroscopic image is corrected based on the proportional relationship between the first tube current and the second tube current. Therefore, the section where the tube current undergoes a transition change is considered, improving the quality of the subtracted image.

[0103] In one embodiment, the method includes: determining the mapping relationship in an interpolation manner, where the mapping relationship includes a linear mapping relationship or a non-linear mapping relationship; the non-linear mapping relationship includes at least one of the following: exponential function; power function; logarithmic function; polynomial function, etc.

[0104] The above exemplary description shows typical examples of the mapping relationship. Those skilled in the art can realize that such a description is only exemplary and is not used to limit the protection scope of the embodiments of the present invention.

[0105] Figure 2 is a schematic diagram showing the mapping relationship between the tube current and the exposure moment when the tube current changes in the continuous mode according to the embodiments of the present invention. In Figure 2 the abscissa is the exposure moment (T), and the ordinate is the tube current. Ts is the duration of the transition change section 22, and Ts is equal to mt2 - mt1.

[0106] It can be seen that in the first section 21 (corresponding to the exposure time T being less than or equal to mt1), the tube current remains unchanged at mA0. In the third section 23 (corresponding to the exposure time being greater than mt2), the tube current remains unchanged at mA1. In the transition section 22 (corresponding to the exposure time being greater than mt1 and less than or equal to ms2), there is a mapping relationship between the tube current and the exposure time. Based on the historical value pairs (including historical tube current and historical exposure time) in the transition section 22, the specific function expression of the mapping relationship of the transition section can be interpolated, and the interpolation method can be linear interpolation or non - linear interpolation.

[0107] Example: Assume the mask image is I m ; r2 is the correction factor of the third section 23, r2 = mA1 / mA0; f(T) / mA0 is the correction factor of the transition section 22; the first section 21 does not require correction; where mt1 is the starting time of the transition section 22; mt2 is the ending time of the transition section 22; f() is the specific function expression of the mapping relationship of the transition section; f(T) is the first tube current when the exposure time is T in the transition section (i.e., mt1 < T ≤ mt2); T is the exposure time of the fluoroscopic image; the fluoroscopic image before correction is I n ; the corrected fluoroscopic image in the third section 23 is I n / r2; mA0 is the tube current in the first section 21, that is, the second tube current of the mask image; mA1 is the tube current in the third section 22, that is, the first tube current when mt2 < T.

[0108] Then: The subtracted image DSA image can be determined based on formula (2) n .

[0109]

[0110] Among them:

[0111] (1) When the tube current does not change during the exposure process of the fluoroscopic image (corresponding to T ≤ mt1), based on the mask image I m and the fluoroscopic image I before correction n generate DSA image n .

[0112] (2) When the tube current changes and stabilizes during the exposure process of the fluoroscopic image (corresponding to mt2 < T), based on the mask image I m and the corrected fluoroscopic image ln(I n / r2) generate DSA image n .

[0113] (3) When the tube current of the fluoroscopic image changes and is in the transitional change section 22 (corresponding to mt1 < T ≤ mt2), based on the mask image I m and the corrected fluoroscopic image ln(I n / (f(T) / mA0) to generate the DSA image n .

[0114] Therefore, for the scenario where the exposure time remains unchanged and the tube current changes in the continuous mode, the first tube current within the transitional change section is determined based on the mapping relationship between the tube current and the exposure moment, and the fluoroscopic image is corrected based on the proportional relationship between the first tube current and the second tube current (for example, the quotient of the first tube current and the second tube current). Therefore, the correction process within the transitional change section is considered, improving the quality of the subtracted image.

[0115] Specifically, when linear correction is adopted for the transitional change section, there is the following formula (3):

[0116]

[0117] Where: r2 = mA1 / mA0; T is the exposure moment of the fluoroscopic image.

[0118] (1) When the tube current does not change during the exposure process of the fluoroscopic image (corresponding to T ≤ mt1), based on the mask image I m and the fluoroscopic image I before correction n to generate the DSA image n .

[0119] (2) When the tube current changes and has stabilized during the exposure process of the fluoroscopic image (corresponding to mt2 < T), based on the mask image I m and the corrected fluoroscopic image ln(I n / r2) to generate the DSA image n .

[0120] (3) When the tube current changes and is in the transitional change section during the exposure process of the fluoroscopic image (corresponding to mt1 < T ≤ mt2), based on the mask image I m and the corrected fluoroscopic image to generate the DSA image n .

[0121] Corresponding to the above scenario (3), where the X-ray tube assembly operates in a pulsed mode: The method includes: determining the product of current and time during the exposure of the fluoroscopic image and the product of current and time during the exposure of the mask image; Step 102 specifically includes: determining a correction factor based on the proportional relationship between the product of current and time during the exposure of the fluoroscopic image and the product of current and time during the exposure of the mask image.

[0122] In one embodiment, determining the product of current and time during the exposure of the fluoroscopic image and the product of current and time during the exposure of the mask image may include: receiving, via a communication cable between the control host and the X-ray tube assembly, a first exposure time, a second exposure time, a first tube current, and a second tube current from the X-ray tube assembly; determining a first product of the first exposure time and the first tube current, which is the product of current and time during the exposure of the fluoroscopic image; determining a second product of the second exposure time and the second tube current, which is the product of current and time during the exposure of the mask image. The proportional relationship between the product of current and time during the exposure of the fluoroscopic image and the product of current and time during the exposure of the mask image may include: (1) the quotient of the product of current and time during the exposure of the fluoroscopic image and the product of current and time during the exposure of the mask image; (2) various variation values based on the quotient of the product of current and time during the exposure of the fluoroscopic image and the product of current and time during the exposure of the mask image (for example, multiplying or dividing the quotient by a predetermined coefficient). Step 103 may include: dividing the fluoroscopic image by the correction factor to obtain a corrected fluoroscopic image. Here, dividing the fluoroscopic image by the correction factor specifically means: dividing the gray value of each pixel point in the fluoroscopic image by the correction factor.

[0123] Figure 3 It is a schematic diagram when the product of current and time changes in the pulsed mode according to an embodiment of the present invention.

[0124] In Figure 3 , the horizontal direction represents the number of pulses associated with the exposure moment T, and the vertical direction represents the product of current and time (i.e., the product of tube current and exposure time). mA2 is the changed tube current; mA1 is the previous tube current; ms2 is the changed pulse width time (i.e., exposure time); mA1 is the previous pulse width time. It can be seen that when the number of pulses is less than N, the product of current and time remains ms1*mA1; when the number of pulses is greater than or equal to N, the product of current and time becomes ms2*mA2.

[0125] Example: Assume the mask image is I m ; r3 = (ms2*mA2) / (ms1*mA1); the fluoroscopic image before correction is I n ; the fluoroscopic image after correction is I n / r3.

[0126] Then: the subtracted image DSA image can be determined based on formula (4). n .

[0127]

[0128] Wherein:

[0129] (1) When the current-time product during the exposure process of the fluoroscopic image does not change compared to the current-time product of the mask image (corresponding to the number of pulses less than or equal to N), based on the mask image I m and the fluoroscopic image I without correction n generate DSAimage n .

[0130] (2) When the current-time product during the exposure process of the fluoroscopic image changes compared to the current-time product of the mask image (corresponding to the number of pulses greater than N), based on the mask image I m and the corrected fluoroscopic image (ln(I n / r3)) generate DSAimage n , where r3 = (ms2 * mA2) / (ms1 * mA1).

[0131] Based on the above description, correction can be performed on each original image, and multiple subtracted images corresponding to each original image can be generated. Then, the multiple subtracted images are combined together to generate a Peak Opacification (PCOP) image. Figure 4 is a schematic diagram of the PCOP image generated based on the subtracted image according to an embodiment of the present invention. It can be seen that the PCOP image has uniform brightness, no artifacts, and good imaging quality.

[0132] Figure 5 is a comparison diagram of PCOP images using different correction methods according to an embodiment of the present invention. Figure 5It includes a first sub - figure 51, a second sub - figure 52, a third sub - figure 53, a fourth sub - figure 54, a fifth sub - figure 55, and a sixth sub - figure 56. Among them: The first sub - figure 51 is a sub - figure where the current - time product during the exposure process of the fluoroscopic image is the same as the current - time product during the exposure process of the mask image. It can be seen that the first sub - figure 51 has good quality. The second sub - figure 52 is a sub - figure where the current - time product during the exposure process of the fluoroscopic image is different from the current - time product during the exposure process of the mask image, and it is generated without performing correction on the fluoroscopic image. It can be seen that the phantoms in the second sub - figure 52 are not uniform, and it has lower quality compared to the first sub - figure 51. The third sub - figure 53 is a sub - figure where the current - time product during the exposure process of the fluoroscopic image is different from the current - time product during the exposure process of the mask image, and for the transitional change section of the tube current, correction is directly performed using the changed tube current. It can be seen that the third sub - figure 53 has better quality than the second sub - figure 52, but there are blank areas between the phantoms in the third sub - figure 53. Both the fourth sub - figure 54 and the fifth sub - figure 55 are sub - figures where the current - time product during the exposure process of the fluoroscopic image is different from the current - time product during the exposure process of the mask image, and linear correction is performed for the transitional change section of the tube current. Among them, the number of linear interpolation points in the fourth sub - figure 54 is less than the number of linear interpolation points in the fifth sub - figure 55. The blank area between the phantoms in the fourth sub - figure 54 is larger than the blank area between the phantoms in the fifth sub - figure 55. Therefore, the quality of the fourth sub - figure 54 is inferior to that of the fifth sub - figure 55. The sixth sub - figure 56 is a schematic diagram where the current - time product during the exposure process of the fluoroscopic image is different from the current - time product during the exposure process of the mask image, and the transitional change section of the tube current is discarded. The blank area between the phantoms in the sixth sub - figure 56 is larger than the blank area between the phantoms in the fourth sub - figure 54. Therefore, the quality of the sixth sub - figure 56 is inferior to that of the fourth sub - figure 54.

[0133] Figure 6 It is a comparison chart of the effects of adopting different correction methods according to the embodiments of the present invention. Figure 6 The abscissa is the exposure time, and the ordinate is the gray - scale value.

[0134] The first curve 60 is a gray level curve when the product of current and time during the exposure of the fluoroscopic image is the same as that during the exposure of the mask image. The second curve 61 is a gray level curve when the product of current and time during the exposure of the fluoroscopic image is different from that during the exposure of the mask image and no correction is performed on the fluoroscopic image. The third curve 62 is a gray level curve when the product of current and time during the exposure of the fluoroscopic image is different from that during the exposure of the mask image, and for the transition change section of the tube current, correction is directly performed using the changed tube current. The fourth curve 63 and the fifth curve 64 are gray level curves when the product of current and time during the exposure of the fluoroscopic image is different from that during the exposure of the mask image, and linear correction is performed on the fluoroscopic image. The number of linear interpolation points of the fourth curve 63 is less than that of the fifth curve 64.

[0135] Figure 7 is an exemplary structural diagram of a digital subtraction device for X-ray imaging according to an embodiment of the present invention. As Figure 7 shown, the digital subtraction device 700 for X-ray imaging includes;

[0136] An acquisition module 701 for acquiring a mask image and a fluoroscopic image, wherein the product of current and time during the exposure of the fluoroscopic image is different from that during the exposure of the mask image, and the tube voltage during the exposure of the fluoroscopic image is equal to the tube voltage during the exposure of the mask image; a first determination module 702 for determining a correction factor for the fluoroscopic image; a correction module 703 for correcting the fluoroscopic image based on the correction factor; and a second determination module 704 for determining a digital subtraction image based on the mask image and the corrected fluoroscopic image.

[0137] In one embodiment, the tube current during the exposure of the fluoroscopic image is equal to the tube current during the exposure of the mask image, and the first exposure time during the exposure of the fluoroscopic image is different from the second exposure time during the exposure of the mask image; the acquisition module 701 is used to determine the first exposure time and the second exposure time; the first determination module 702 is used to determine the correction factor based on the proportional relationship between the first exposure time and the second exposure time.

[0138] In one embodiment, the exposure time during the exposure of the fluoroscopic image is equal to the exposure time during the exposure of the mask image, and the first tube current during the exposure of the fluoroscopic image is different from the second tube current during the exposure of the mask image; the acquisition module 701 is used to determine the first tube current and the second tube current; the first determination module 702 is used to determine the correction factor based on the proportional relationship between the first tube current and the second tube current.

[0139] In one embodiment, the exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the first tube current during the exposure process of the fluoroscopic image is different from the second tube current during the exposure process of the mask image; an acquisition module 701 for determining the second tube current and the exposure moment of the fluoroscopic image; a first determination module 702 for determining the mapping relationship between the tube current and the exposure moment within the transition change section of the tube current during the exposure process of the fluoroscopic image; determining the first tube current based on the mapping relationship and the exposure moment of the fluoroscopic image; and determining a correction factor based on the proportional relationship between the first tube current and the second tube current.

[0140] In one embodiment, the acquisition module 701 is configured to determine the current-time product during the exposure process of the fluoroscopic image and the current-time product during the exposure process of the mask image; the first determination module 702 is configured to determine a correction factor based on the proportional relationship between the current-time product during the exposure process of the fluoroscopic image and the current-time product during the exposure process of the mask image.

[0141] An embodiment of the present invention also provides a control host in an X-ray imaging system having a processor-memory architecture. Figure 8 is a structural diagram of the control host according to an embodiment of the present invention. As Figure 8 shown, the control host 800 includes a processor 801, a memory 802, and a computer program stored on the memory 802 and executable on the processor 801. When the computer program is executed by the processor 801, it implements any of the digital subtraction methods for X-ray imaging described above. Among them, the memory 802 can be specifically implemented as various storage media such as electrically erasable programmable read-only memory (EEPROM), flash memory, programmable read-only memory (PROM), etc. The processor 801 can be implemented as including one or more central processing units or one or more field-programmable gate arrays, where the field-programmable gate array integrates one or more central processing unit cores. Specifically, the central processing unit or the central processing unit core can be implemented as a CPU, an MCU, a DSP, etc.

[0142] Preferably, the X-ray imaging system includes a mobile X-ray imaging system or a stationary X-ray imaging system. The mobile X-ray imaging system (e.g., a mobile C-arm X-ray machine) is used to provide X-ray imaging of a patient's anatomical structure in clinical applications. For example, clinical applications may include: interventional fluoroscopy; orthopedics; urology; pain management; plastic surgery; neurology; vascular; intensive care unit and emergency room procedures, etc. Due to its compact design and user-friendliness, the mobile X-ray imaging system is widely used. The mobile X-ray imaging system is usually arranged in an operating room or an interventional room. The stationary X-ray imaging system can be implemented as a direct digital radiography (DR) system or a stationary C-arm X-ray machine, etc. The DR imaging system is usually arranged in a radiographic room, and the stationary C-arm X-ray machine can be used for processes such as angiography.

[0143] It should be noted that not all steps and modules in the above processes and structure diagrams are necessary, and some steps or modules can be ignored according to actual needs. The execution order of each step is not fixed and can be adjusted according to needs. The division of each module is only for the convenience of description in terms of functional division. In actual implementation, one module can be implemented by multiple modules, and the functions of multiple modules can also be implemented by the same module. These modules can be located in the same device or in different devices.

[0144] The hardware modules in each embodiment can be implemented mechanically or electronically. For example, a hardware module can include a specially designed permanent circuit or logic device (such as a dedicated processor, such as an FPGA or an ASIC) for performing specific operations. A hardware module can also include a programmable logic device or circuit (such as including a general-purpose processor or other programmable processors) temporarily configured by software for performing specific operations. As for whether to specifically use a mechanical method, a dedicated permanent circuit, or a temporarily configured circuit (such as configured by software) to implement the hardware module, it can be determined based on cost and time considerations.

[0145] The above is only a preferred embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A digital subtraction method for X-ray photography, characterized in that Comprising; Obtaining a mask image and a fluoroscopic image, wherein the charge-time product during the exposure process of the fluoroscopic image is different from the charge-time product during the exposure process of the mask image, and the tube voltage during the exposure process of the fluoroscopic image is equal to the tube voltage during the exposure process of the mask image (101); Determining a correction factor for the fluoroscopic image (102); Correcting the fluoroscopic image based on the correction factor (103); Determining a digital subtraction image based on the mask image and the corrected fluoroscopic image (104).

2. The method according to claim 1, wherein The tube current during the exposure process of the fluoroscopic image is equal to the tube current during the exposure process of the mask image, and the first exposure time during the exposure process of the fluoroscopic image is different from the second exposure time during the exposure process of the mask image; The method includes: determining the first exposure time and the second exposure time; The determining the correction factor for the fluoroscopic image (102) includes: determining the correction factor based on the proportional relationship between the first exposure time and the second exposure time.

3. The method according to claim 1, characterized in that, The exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the first tube current during the exposure process of the fluoroscopic image is different from the second tube current during the exposure process of the mask image; The method includes: Determining the first tube current and the second tube current; The determining the correction factor for the fluoroscopic image (102) includes: Determining the correction factor based on the proportional relationship between the first tube current and the second tube current.

4. The method according to claim 1, wherein The exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the first tube current during the exposure process of the fluoroscopic image is different from the second tube current during the exposure process of the mask image; The method includes: Determining the second tube current and the exposure moment of the fluoroscopic image; The determining the correction factor for the fluoroscopic image (102) includes: Determining the mapping relationship between the tube current and the exposure moment within the transition change section of the tube current during the exposure process of the fluoroscopic image; Determining the first tube current based on the mapping relationship and the exposure moment of the fluoroscopic image; Determining the correction factor based on the proportional relationship between the first tube current and the second tube current.

5. The method according to claim 4, wherein The method includes: Determining the mapping relationship in an interpolation manner, wherein the mapping relationship includes a linear mapping relationship or a non-linear mapping relationship; The non-linear mapping relationship includes at least one of the following: Exponential function; power function; logarithmic function; polynomial function.

6. The method according to claim 1, characterized in that The method includes: Determining the charge-time product during the exposure process of the fluoroscopic image and the charge-time product during the exposure process of the mask image; The determining the correction factor for the fluoroscopic image (102) includes: Determining the correction factor based on the proportional relationship between the charge-time product during the exposure process of the fluoroscopic image and the charge-time product during the exposure process of the mask image.

7. A digital subtraction device (700) for X-ray photography, characterized in that, Comprising; An acquisition module (701) for acquiring a mask image and a fluoroscopic image, wherein the charge-time product during the exposure process of the fluoroscopic image is different from the charge-time product during the exposure process of the mask image, and the tube voltage during the exposure process of the fluoroscopic image is equal to the tube voltage during the exposure process of the mask image; A first determination module (702) for determining a correction factor for the fluoroscopic image; A correction module (703) for correcting the fluoroscopic image based on the correction factor; A second determination module (704) for determining a digital subtraction image based on the mask image and the corrected fluoroscopic image.

8. The device (700) according to claim 7, characterized in that, The tube current during the exposure process of the fluoroscopic image is equal to the tube current during the exposure process of the mask image, and the first exposure time during the exposure process of the fluoroscopic image is different from the second exposure time during the exposure process of the mask image; The acquisition module (701) for determining the first exposure time and the second exposure time; The first determination module (702) for determining the correction factor based on the proportional relationship between the first exposure time and the second exposure time.

9. The device (700) according to claim 7, characterized in that, The exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the first tube current during the exposure process of the fluoroscopic image is different from the second tube current during the exposure process of the mask image; The acquisition module (701) for determining the first tube current and the second tube current; The first determination module (702) for determining the correction factor based on the proportional relationship between the first tube current and the second tube current.

10. The apparatus (700) according to claim 7, wherein, The exposure time during the exposure process of the fluoroscopic image is equal to the exposure time during the exposure process of the mask image, and the first tube current during the exposure process of the fluoroscopic image is different from the second tube current during the exposure process of the mask image; The acquisition module (701) for determining the second tube current and the exposure moment of the fluoroscopic image; The first determination module (702) for determining the mapping relationship between the tube current and the exposure moment within the transitional change section of the tube current during the exposure process of the fluoroscopic image; Determining the first tube current based on the mapping relationship and the exposure moment of the fluoroscopic image; Determining the correction factor based on the proportional relationship between the first tube current and the second tube current.

11. The apparatus (700) according to claim 7, wherein The acquisition module (701) for determining the charge-time product during the exposure process of the fluoroscopic image and the charge-time product during the exposure process of the mask image; The first determination module (702) for determining the correction factor based on the proportional relationship between the charge-time product during the exposure process of the fluoroscopic image and the charge-time product during the exposure process of the mask image.

12. A control host (800) of an X-ray imaging system, characterized in that, Comprising: A processor (801); A memory (802) for storing executable instructions of the processor (801); The processor (801) is configured to read the executable instructions from the memory (802) and execute the executable instructions to implement the digital subtraction method for X-ray radiography according to any one of claims 1-6.

13. A computer-readable storage medium having computer instructions stored thereon, characterized in that, When the computer instructions are executed by a processor, the digital subtraction method for X-ray radiography according to any one of claims 1-6 is implemented.

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