Cardiac CT imaging control method, device, medium and cardiac CT imaging equipment

Abstract

The present disclosure provides a cardiac CT imaging control method, device, medium and cardiac CT imaging equipment, which relate to the field of medical imaging technology. The method includes: in response to the start signal of the first scanning stage, the collimator of the cardiac CT imaging equipment is adjusted to the narrow opening working mode, the exposure current is adjusted to the low exposure dose mode, and the projection data of the central cross section of the heart corresponding to different times in the first scanning stage is collected, and then the exposure time corresponding to the optimal phase in the second scanning stage is determined; in response to the start signal of the second scanning stage, the collimator is adjusted to the wide opening working mode, the exposure current is adjusted to the high exposure dose mode, and the projection data of the heart corresponding to the exposure time in the second scanning stage is collected, and then the first reconstructed image of the heart at the optimal phase is determined. This method does not require ECG gating, and can obtain high-quality reconstructed images of the heart in a low motion state in a scenario where the exposure dose is increased by a very small amount.

Description

Technical Field

[0001] The present disclosure relates to the field of medical imaging technology, and in particular to a cardiac CT imaging control method, device, medium and cardiac CT imaging equipment. Background Art

[0002] Computed tomography (CT) technology, as an important medical imaging diagnostic tool, has been widely used in clinical medicine. CT-based scanning of the human heart and its coronary arteries is an important means of detecting coronary artery stenosis, coronary artery calcification scoring, coronary artery malformation and variation, and myocardial ischemia.

[0003] In the current cardiac CT imaging control method, in order to reduce the impact of cardiac motion on image quality, electrocardiogram (ECG) gating technology is usually used, that is, an exposure control scheme based on the ECG signal of the examinee, which selects a specific phase when the heart is relatively still for exposure scanning. However, on the one hand, ECG gating technology brings additional design and implementation processes to cardiac CT imaging, such as synchronous processing of scan projection data and ECG signals, R wave detection and other processing. On the other hand, the pasting of ECG electrodes and signal acquisition processes may make some examinees feel uncomfortable, and the quality of ECG signals is easily disturbed, making the existing cardiac CT imaging control method ineffective. In addition, motion artifacts are prone to appear after image reconstruction, and it is necessary to rescan to obtain an image with the optimal phase as the final clinical diagnostic image.

[0004] Although the optimal phase automatic identification solutions provided by Chinese patents CN116849691B, CN110969633B, etc. can automatically track the optimal phase, the acquisition of the optimal phase depends on CT images of different phases, which causes the inspected person to be exposed to a high exposure dose of radioactive rays for a long time, posing a great health hazard. Summary of the invention

[0005] The main purpose of the present disclosure is to provide a cardiac CT imaging control method, device, medium and cardiac CT imaging equipment to solve the technical problems in related technologies that the imaging results are easily disturbed due to the use of ECG gating technology and the exposure measurement required to achieve automatic tracking of the optimal phase is too high.

[0006] In order to achieve the above-mentioned object, the first aspect of the present disclosure provides a cardiac CT imaging control method, comprising:

[0007] In response to a start signal of the first scanning phase, after adjusting the collimator of the cardiac CT imaging device to a narrow opening working mode and the exposure current to a low exposure dose mode, the cardiac CT imaging device collects projection data of a central cross section of the heart corresponding to different times in the first scanning phase, and then determines an exposure time corresponding to an optimal phase in the second scanning phase based on the projection data;

[0008] In response to the start signal of the second scanning phase, after the collimator is adjusted to the large opening working mode and the exposure current is adjusted to the high exposure dose mode, the projection data of the heart corresponding to the exposure moment in the second scanning phase is collected by the cardiac CT imaging device, and then the first reconstructed image of the heart at the optimal phase is determined based on the projection data.

[0009] Further, in the narrow opening working mode, the radiation source of the cardiac imaging device is configured to irradiate the central cross section of the heart; in the wide opening working mode, the radiation source is configured to irradiate the entire heart; and,

[0010] The scanning duration of the first scanning phase includes at least one complete heartbeat cycle.

[0011] Furthermore, after adjusting the collimator of the cardiac CT imaging device to a narrow opening working mode and the exposure current to a low exposure dose mode, the cardiac CT imaging device is used to collect projection data of the central cross section of the heart corresponding to different times in the first scanning phase, including:

[0012] Adjusting the width of the shielding opening of the collimator to a set value so that the radiation range of the radiation source covers the entire central cross section of the heart;

[0013] The exposure current is set according to a pre-selected image quality parameter; wherein the exposure current is a minimum exposure dose based on satisfying the image quality parameter;

[0014] selecting a scan duration of the first scan phase and the different times for data acquisition;

[0015] The projection data of the heart center cross section corresponding to each of the different times are collected by the heart CT imaging device.

[0016] Further, the step of determining the exposure time corresponding to the optimal phase in the second scanning stage based on the projection data includes:

[0017] Respectively perform image reconstruction according to the projection data of the heart center cross section corresponding to each time, to obtain a multi-phase reconstructed image of the heart center cross section;

[0018] Determine the optimal phase corresponding to the cardiac motion cycle and image artifact minimization based on the multi-phase reconstructed image;

[0019] The exposure time and exposure duration of the second scanning stage are determined based on the cardiac motion cycle and the optimal phase.

[0020] Furthermore, the different times of the first scanning stage are distributed at equal intervals, and the first scanning stage and the second scanning stage both adopt a wide-body tomographic prospective cardiac scanning mode; and the method further includes:

[0021] In the second scanning stage, the cardiac CT imaging device also collects projection data of the heart corresponding to other preset moments in the exposure duration except the exposure moment, and image reconstruction is performed based on the projection data corresponding to the exposure moment in the second scanning stage and the other preset moments, and the reconstruction result corresponding to the minimized image artifacts is selected as the second reconstructed image of the heart at the optimal phase.

[0022] Furthermore, determining the optimal phase corresponding to minimizing the cardiac motion cycle and image artifacts based on the multi-phase reconstructed image includes:

[0023] Determining the similarity between each group of adjacent images in the multi-phase reconstructed image;

[0024] Establishing an image difference feature change curve based on the similarity, wherein the abscissa of the image difference feature change curve is time and the ordinate is the similarity;

[0025] The cardiac motion cycle and the optimal phase are determined respectively based on the image difference characteristic change curve.

[0026] Further, the cardiac motion cycle is configured to be equal to the distance between adjacent minimum value points or the distance between adjacent maximum value points in the image difference characteristic change curve; and,

[0027] The optimal phase is configured to be equal to the phase of the last minimum point in the image difference characteristic change curve;

[0028] The exposure time T of the second scanning stage 3 , exposure time P exp They are configured as:

[0029] T 3 =P Send + ⌈(max(T now -T 2 ,T prepare ) + T shift ⌉×Prange -T shift

[0030] P exp = 2 × T shift

[0031] in,

[0032] T shift = R / 2×(180+Fan) / 360) / P range + DeltaT

[0033] Where P Send is the time when the optimal phase is located, T now is the current moment, T 2 is the exposure end time of the first scanning stage, T prepare is the fixed response time required for the hardware of the cardiac CT imaging device to switch from the narrow opening working mode to the large opening working mode, P range is the cardiac cycle, T shift To reconstruct an image, the cardiac CT imaging device needs to consume half of the data acquisition time, DeltaT is the redundant time, R is the time taken for the scanning gantry in the cardiac CT imaging device to rotate one circle, and Fan is the opening angle of the detector in the cardiac CT imaging device.

[0034] A second aspect of the present disclosure provides a cardiac CT imaging control device, comprising:

[0035] a first control unit configured to, in response to a start signal of the first scanning phase, adjust the collimator of the cardiac CT imaging device to a narrow opening working mode and the exposure current to a low exposure dose mode, and then collect projection data of a central cross section of the heart corresponding to different times in the first scanning phase through the cardiac CT imaging device, and then determine an exposure time corresponding to an optimal phase in a second scanning phase based on the projection data;

[0036] The second control unit is configured to respond to the start signal of the second scanning stage, adjust the collimator to a large-opening working mode and the exposure current to a high exposure dose mode, and then collect projection data of the heart corresponding to the exposure moment in the second scanning stage through the cardiac CT imaging device, and then determine a first reconstructed image of the heart at the optimal phase based on the projection data.

[0037] A third aspect of the present disclosure provides a computer-readable storage medium storing computer instructions for causing a computer to execute the cardiac CT imaging control method provided in any one of the first aspects.

[0038] A fourth aspect of the present disclosure provides a cardiac CT imaging device, comprising: a radiation source, a detector, a collimator, a scanning gantry, at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor executes the cardiac CT imaging control method provided in any one of the first aspects.

[0039] The cardiac CT imaging control method provided by the disclosed embodiment adopts a prospective cardiac scanning mode without ECG gating. After tracking the motion pattern of the central cross section of the heart within a certain time range in the first scanning stage, the exposure time of the second scanning stage is obtained, thereby controlling the second scanning stage to achieve a large-opening prospective cardiac scanning mode, achieving the purpose of getting rid of ECG gating and obtaining a reconstructed image of the heart in a low-motion state with a very small increase in exposure dose, thereby achieving the technical effect of anti-interference and reducing exposure measurement, and further solving the technical problems in the related technology that the imaging results are easily interfered with due to the use of ECG gating technology, and the exposure measurement required for automatically tracking the optimal phase is too high. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the specific embodiments of the present disclosure or the technical solutions in the related technologies, the drawings required for use in the specific embodiments or the related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 A schematic diagram of a method flow chart provided in an embodiment of the present disclosure;

[0042] Figure 2 A schematic diagram of the opening change of the collimator corresponding to two scanning stages in the method provided in an embodiment of the present disclosure;

[0043] Figure 3 A schematic diagram of selecting two scanning stages in the method provided in an embodiment of the present disclosure;

[0044] Figure 4 A schematic diagram of a curve of image difference feature changes obtained through the first scanning stage in the method provided in an embodiment of the present disclosure;

[0045] Figure 5 A block diagram of a cardiac CT imaging control device provided in an embodiment of the present disclosure;

[0046] Figure 6A block diagram of a cardiac CT imaging device provided in an embodiment of the present disclosure.

[0047] Reference numerals:

[0048] 15- Radiation source; 16- Collimator; 17- Detector; 19- Heart; T 1 - The exposure time of the first scanning stage; T 2 - The end time of exposure in the first scanning stage; T 3 - Exposure time of the second scanning stage; I 1 - Image 1; I N - Nth image; P 1 - The time corresponding to the first image; P N - The time corresponding to the Nth image. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the scheme of the present disclosure, the technical scheme in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present disclosure.

[0050] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present disclosure described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0051] In the present disclosure, the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", etc. are based on the directions or positional relationships shown in the drawings. These terms are mainly used to better describe the present disclosure and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific direction, or to be constructed and operated in a specific direction.

[0052] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this disclosure can be understood according to specific circumstances.

[0053] In addition, the term "prospective cardiac scanning mode" refers to the pre-setting of the scanning range and related parameters, which can scan the heart in a targeted manner. This mode can obtain clear cardiac images while reducing unnecessary radiation doses when scanning fast-moving organs such as the heart through reasonable parameter settings and scan planning. In the diagnosis of coronary artery disease, it can clearly display the stenosis or blockage of the coronary arteries. In the diagnosis of cardiomyopathy, combined with the characteristics of wide-body tomography, the heart can be observed from different angles, which helps to evaluate the thickness, function and tissue characteristics of the myocardium, and provide detailed imaging basis for the diagnosis of cardiomyopathy.

[0054] The term "wide-body tomography prospective cardiac scanning mode" refers to the combination of the wide coverage of wide-body tomography and the pre-planning of the prospective cardiac scanning mode, which can scan the heart more efficiently. For example, in one scan, the wide-body detector can cover the key parts of the heart, and the prospective mode ensures the accuracy and targeting of the scan, reducing the radiation risk and time cost caused by repeated or unnecessary scans. In the diagnosis of heart valve disease, this combination can more clearly show the structure and function of the heart valve.

[0055] The term "heart center section" refers to a cross-sectional image through the center of the heart that is essential for understanding and evaluating the structure and function of the heart.

[0056] The term "exposure current" refers to the current used to generate images in cardiac CT imaging technology. In X-ray photography, exposure current is closely related to tube current and is one of the important parameters that affect image quality and diagnostic information.

[0057] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure may be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0058] The related technology has technical problems that the imaging results are easily disturbed due to the use of ECG gating technology, and the exposure measurement required to achieve automatic tracking of the optimal phase is too high.

[0059] In order to solve the above technical problems, the present disclosure provides a cardiac CT imaging control method, such as Figure 1 As shown, the method includes the following steps S11 to S12.

[0060] Step S11: In response to the start signal of the first scanning stage, the collimator of the cardiac CT imaging device is adjusted to the narrow opening working mode and the exposure current is adjusted to the low exposure dose mode, and then the projection data of the central cross section of the heart corresponding to different times in the first scanning stage is collected by the cardiac CT imaging device, and then the exposure time corresponding to the optimal phase in the second scanning stage is determined based on the projection data.

[0061] Step S12: In response to the start signal of the second scanning stage, after the collimator is adjusted to the large-opening working mode and the exposure current is adjusted to the high exposure dose mode, the projection data of the heart corresponding to the exposure time in the second scanning stage is collected by the cardiac CT imaging device, and then the first reconstructed image of the heart at the optimal phase is determined based on the projection data.

[0062] It should be noted that the above method divides the exposure scan of the heart of the examinee into two stages. In the first scanning stage, the central cross section of the heart of the examinee is scanned based on low exposure dose radiation to reduce the additional irradiation dose of the examinee, and the optimal phase in the second scanning stage is determined by the projection data at different times of the first scanning stage, and the exposure time and exposure duration corresponding to the optimal phase are obtained. In the second scanning stage, the heart of the examinee is scanned based on high exposure dose radiation at the exposure moment, and finally a first reconstructed image with a clear optimal phase is obtained. The specific narrow opening working mode, large opening working mode, low exposure dose mode, and high exposure dose mode can be set according to actual exposure requirements, and the embodiments of the present disclosure are not limited to this. The specific method for determining the exposure time corresponding to the optimal phase in the second scanning stage based on projection data can be set according to actual needs, for example, the exposure time is determined by a big data model, a trained neural network, a vector machine, etc. The specific first reconstructed image of the heart at the optimal phase based on projection data can refer to the image reconstruction method of the related art.

[0063] Compared with the related art, the above method adopts a prospective heart scanning mode that does not require ECG gating. After tracking the movement pattern of the central cross-section of the heart within a certain time range in the first scanning stage, the exposure time of the second scanning stage is obtained, thereby controlling the second scanning stage to achieve a large-opening prospective heart scanning mode, achieving the purpose of getting rid of ECG gating and obtaining a reconstructed image of the heart in a low-motion state with a very small increase in exposure dose, thereby achieving the technical effect of anti-interference and reducing exposure measurement, and further solving the technical problems of the related art that the imaging results are susceptible to interference due to the use of ECG gating technology and the exposure measurement required for automatic tracking of the optimal phase is too high.

[0064] exist Figure 1Based on the method shown, preferably, in the narrow opening working mode, the ray source of the cardiac imaging device is configured to radiate the central cross section of the heart. In the wide opening working mode, the ray source is configured to radiate the entire heart. In addition, the scanning duration of the first scanning stage includes at least one complete heartbeat cycle. Through the above-mentioned opening setting and the setting of the scanning duration of the first scanning stage, the first scanning stage can track the motion pattern of the entire central cross section of the heart within a certain time range, which is conducive to obtaining a more accurate exposure control effect in the second scanning stage.

[0065] Under ideal conditions, the center of the heart center section, the center of the shielding opening of the collimator, and the ray source of the cardiac CT imaging device can be located on the same straight line to achieve accurate observation and positioning of the heart center section. In actual application, there may be some deviations in the position of the heart. As long as it is within the allowable error range and the ray source can irradiate the heart center section in the narrow opening working mode, the goal of step S11 can be achieved to locate the exposure time corresponding to the optimal phase of the second scanning stage.

[0066] exist Figure 1 Based on the method shown in FIG. 1 , preferably, in the first scanning phase, different times of data acquisition are distributed at equal intervals, and the scanning duration of the first scanning phase ( Figure 3 T 1 Time-T 3 The time (time) can be configured as a fixed length or an adaptive length based on the projection data. The fixed length can be obtained based on clinical statistical rules, such as 2s, during which most people will have at least one complete heartbeat. The adaptive length can be obtained based on real-time calculation.

[0067] exist Figure 1 Based on the method shown, preferably, the first scanning stage and the second scanning stage both adopt the wide-body tomographic prospective cardiac scanning mode. In addition, the scanning speed of the CT scanner in the first scanning stage and the second scanning stage is the same, for example, the rotation speed required for coronary artery scanning (the time taken for one rotation). The wide-body tomographic prospective cardiac scanning mode combines a wide-body detector and a high-speed rotating gantry, and can complete a comprehensive scan of the heart in a very short time, thereby providing a high-resolution cardiac image.

[0068] exist Figure 1 Based on the method shown, preferably, the method further includes step S13 to achieve further image optimization function.

[0069] Step S13: In the second scanning stage, projection data of the heart corresponding to other preset moments in the exposure duration except the exposure moment is also collected by the cardiac CT imaging device, and image reconstruction is performed based on the projection data corresponding to the exposure moment and other preset moments in the second scanning stage, and the reconstruction result corresponding to the minimized image artifacts is selected as the second reconstructed image of the heart at the optimal phase.

[0070] Specifically, how to select the corresponding reconstruction result with minimized image artifacts can be referred to the description of the following sub-step S116, which will not be repeated here. Through step S13, image artifacts can be further reduced to provide a high-resolution heart image.

[0071] Figure 2 Schematic diagram of the opening change of the collimator corresponding to the two scanning stages in the method provided in the embodiment of the present disclosure. Figure 2 As shown, in the first scanning stage, the collimator 16 is in the narrow opening working mode, and the ray source 15 is configured to radiate the central cross section of the heart. In the second scanning stage, the collimator 16 is in the wide opening working mode, and the ray source 15 is configured to radiate the entire heart 19. The position of the ray source 15 can be set to be fixed or adjustable, and the embodiments of the present disclosure are not limited to this. For the narrow opening working mode, for example, the shielding opening of the collimator 16 can select the minimum opening, such as the 4×0.625 mm mode. The wide opening working mode can be set to the common working mode of CT imaging.

[0072] In the first scanning stage, in order to further reduce the additional radiation to the examinee and obtain good image contrast quality, step S11 can be further implemented through the following sub-steps S111 to S117.

[0073] Sub-step S111: adjusting the width of the shielding opening of the collimator to a set value so that the radiation range of the ray source covers the entire central cross section of the heart.

[0074] Sub-step S112: setting an exposure current according to a pre-selected image quality parameter, wherein the exposure current is a minimum exposure dose based on satisfying the image quality parameter.

[0075] Sub-step S113: selecting the scanning duration of the first scanning phase and different times for data collection.

[0076] Sub-step S114: using a cardiac CT imaging device, respectively collecting projection data of the central cross section of the heart corresponding to each time at different times.

[0077] Sub-step S115: performing image reconstruction according to the projection data of the heart center section corresponding to each time, to obtain a multi-phase reconstructed image of the heart center section.

[0078] Sub-step S116: Determine the optimal phase corresponding to the cardiac motion cycle and image artifact minimization based on the multi-phase reconstructed image.

[0079] Sub-step S117: Determine the exposure time and exposure duration of the second scanning stage based on the cardiac motion cycle and the optimal phase.

[0080] In sub-step S112, the exposure current is reduced as much as possible on the basis of satisfying the image contrast quality, so as to minimize the additional irradiation dose to the examinee.

[0081] Sub-step S115 further includes: performing data processing (including calibration, etc.) on the projection data of the heart center section corresponding to each time; performing image reconstruction on the projection data after data processing to obtain a multi-phase reconstructed image of the heart center section. Specifically, after the projection data is collected, data processing, image reconstruction (half-scan reconstruction) and other steps are promptly performed to obtain the heart scanning position (heart center section) at different times (such as Figure 4 P 1 ,…P N ) corresponding image. In this process, due to the small opening, the amount of data to be processed at each time is very small, and the number of images reconstructed at a single time can be set to 1, so the time from data acquisition to image reconstruction will be very short, much shorter than the human heart movement cycle. According to the specified time interval dT (such as Figure 4 P 1 ,…P N , where P i+1 -P i =dT, i=1,…N), and reconstruct a series of images step by step. This series of images is at the same position in space, but is evenly spaced in time, and the result can represent the state of the heart's movement over time. It should be noted that the time distribution can also be set to be non-evenly spaced.

[0082] According to the half-scan reconstruction, the first image corresponds to the moment P 1 Expressed as: P 1 = T 1 + R / 2×(180+Fan) / 360, where T 1 is the exposure time of the first scanning stage, Fan is the angle of the detector in the cardiac CT imaging device, and R is the time taken for the scanning gantry in the cardiac CT imaging device to rotate one circle. Based on this, the time corresponding to any reconstructed image can be further obtained: i = (i-1)×dT + T 1 + R / 2×(180+Fan) / 360.

[0083] Sub-step S116 further includes: determining the similarity between each group of adjacent images in the multi-phase reconstructed image; establishing an image difference feature change curve based on the similarity, wherein the abscissa of the image difference feature change curve is time and the ordinate is similarity; and determining the optimal phase corresponding to the heart motion cycle and image artifact minimization based on the image difference feature change curve. Specifically, the image difference feature change curve can be established by using the method of calculating the similarity of adjacent images through the following formula, such as Figure 4 As shown:

[0084] I i diff = f similar (I i+1 , I i )

[0085] In the formula, I i+1 is the i+1th image, I i is the i-th image, I i diff is the similarity, f similar () is the similarity function.

[0086] In practical applications, the implementation of the similarity function can adopt different schemes according to the effect and needs. For example, it can be achieved by calculating the mean square error MSE of the two images, the structural similarity index SSIM, histogram difference, deep learning features, etc. Finally, the image difference feature change curve is obtained as follows Figure 4 As shown, I i diff The smaller the value, the more similar the two images are.

[0087] For the above image difference feature change curve, we can use simple local maximum and minimum traversal methods to obtain their respective positions (such as obtaining the maximum or minimum value by sliding the window with a specified sampling length), or use more complex methods to locate the local maximum and minimum change period intervals, such as the dynamic time warping (DTW) method. Then, we can obtain the local minimum point position in the image difference feature change curve {S i} and the local maximum point position {B i Then, the distance between adjacent minimum points and the distance between adjacent maximum points can be obtained. If there are multiple minimum points or multiple maximum points, the average value of the distance can be taken.

[0088] As a preferred embodiment, the cardiac motion cycle is configured to be equal to the distance between adjacent minimum points or the distance between adjacent maximum points in the image difference characteristic change curve. The optimal phase is configured to be equal to the phase of the last minimum point in the image difference characteristic change curve. The exposure time T of the second scanning stage3 , exposure time P exp They are configured as:

[0089] T 3 =P Send + ⌈(max(T now -T 2 ,T prepare ) + T shift ⌉×P range -T shift

[0090] P exp = 2 × T shift

[0091] in,

[0092] T shift = R / 2×(180+Fan) / 360) / P range + DeltaT

[0093] Where P Send is the time when the optimal phase is located, T now is the current moment, T 2 is the exposure end time of the first scanning stage, T prepare is the fixed response time required for the hardware of the cardiac CT imaging device to switch from the narrow-opening working mode to the wide-opening working mode, P range is the cardiac motion cycle (equal to the distance between adjacent minimum points or the distance between adjacent maximum points in the image difference characteristic change curve), T shift To reconstruct an image, the cardiac CT imaging device needs to consume half of the data acquisition time, DeltaT is the redundant time, ⌈⌉ is the rounding up operation, and max() is the maximum value operation.

[0094] In the extreme case, T shift = R / 2×(180+Fan) / 360) / P range In order to increase the exposure success rate, you can also increase its value and set DeltaT according to the actual situation.

[0095] For sub-step S117, an exposure control signal of the second scanning stage is generated according to the exposure time and exposure duration of the second scanning stage, so as to control the exposure of the second scanning stage.

[0096] For step S13, the data exposed in the second scanning stage can support the reconstruction of multiple sequences of reconstructed image results according to the specified time interval dT, such as {I 1 ,I 2 ,…,I N}, at this time, the local minimum point position {S i}The same method is used to determine the result with the smallest difference in the reconstructed image sequence and output it as the final reconstruction result.

[0097] From the above description, it can be seen that the present disclosure achieves the following technical effects:

[0098] 1. Based on high-end wide-body CT, it adopts a wide-body tomographic prospective cardiac scanning mode, combined with a wide-body detector and a high-speed rotating gantry, which can complete a comprehensive scan of the heart in a short time and provide high-resolution cardiac structure images.

[0099] 2. It eliminates the need to obtain ECG signals and realizes a non-ECG-gated cardiac tomography prospective scanning reconstruction method. It is not necessary to attach an ECG patch to the subject, avoiding the inconvenience of the subject's ECG signal acquisition process. In addition, it reduces the complexity of equipment and algorithm signal processing and simplifies the process of cardiac scanning.

[0100] 3. It is necessary to control the opening and closing of the collimator to reduce overexposure, and use a narrow collimation opening (narrow opening working mode) to expose and obtain projection data within a certain time range of the local heart. Compared with ECG-gated free heart rate scanning, it increases the probability of tracking the optimal phase (optimal scanning heart rate range).

[0101] 4. Determine the optimal phase (best phase) corresponding to the cardiac motion cycle and image artifact minimization based on multi-phase reconstruction images without significantly increasing the additional exposure dose.

[0102] 5. Based on the calculated cardiac motion cycle and optimal phase, the exposure moment (exposure timing) and exposure duration (duration) can be controlled to obtain better image quality than related technologies.

[0103] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0104] The present disclosure also provides a cardiac CT imaging control device for implementing the above method embodiment. Figure 5 As shown, the cardiac CT imaging control device 20 includes a first control unit 201 and a second control unit 202 .

[0105] The first control unit 201 is configured to respond to the start signal of the first scanning stage, adjust the collimator of the cardiac CT imaging device to a narrow opening working mode and the exposure current to a low exposure dose mode, and then collect projection data of the central cross-section of the heart corresponding to different times in the first scanning stage through the cardiac CT imaging device, and then determine the exposure time corresponding to the optimal phase in the second scanning stage based on the projection data.

[0106] The second control unit 202 is configured to respond to the start signal of the second scanning stage, adjust the collimator to the large opening working mode and the exposure current to the high exposure dose mode, and then collect the projection data of the heart corresponding to the exposure time in the second scanning stage through the cardiac CT imaging equipment, and then determine the reconstructed image of the heart at the optimal phase based on the projection data.

[0107] The specific manner in which each unit in the above device embodiment performs operations has been described in detail in the embodiment of the method, and will not be elaborated on here.

[0108] The present disclosure also provides a cardiac CT imaging device, such as Figure 6 As shown, the cardiac CT imaging device includes a ray source 15, a collimator 16, a detector 17, a scanning gantry 18, one or more processors 11 and a memory 12. Figure 6 A processor 11 is taken as an example.

[0109] The controller may further include: an input device 13 and an output device 14 .

[0110] The processor 11, the memory 12, the input device 13 and the output device 14 may be connected via a bus or other means. Figure 5 The example of connecting through bus is taken in the following.

[0111] The processor 11 may be a central processing unit (CPU), or other general-purpose processors, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or a combination of the above chips. The general-purpose processor may be a microprocessor or any conventional processor.

[0112] The memory 12 is a non-transient computer-readable storage medium that can be used to store non-transient software programs, non-transient computer executable programs and modules, such as program instructions / modules corresponding to the control method in the embodiment of the present disclosure. The processor 11 executes various functional applications and data processing of the server by running the non-transient software programs, instructions and modules stored in the memory 12, that is, the cardiac CT imaging control method of the above method embodiment is implemented.

[0113] The memory 12 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of a processing device operated by the server, etc. In addition, the memory 12 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 12 may optionally include a memory remotely arranged relative to the processor 11, and these remote memories may be connected to a network connection device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0114] The input device 13 can receive input digital or character information, and generate key signal input related to user settings and function control of the processing device of the server. The output device 14 can include display devices such as a display screen.

[0115] One or more modules are stored in the memory 12, and when executed by one or more processors 11, the execution is as follows: Figure 1 The method shown.

[0116] Those skilled in the art can understand that the implementation of all or part of the processes in the above method embodiments can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes in the above method embodiments. Among them, the storage medium can be a disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory (FM), a hard disk (HDD), or a solid-state drive (SSD), etc.; the storage medium can also include a combination of the above types of memory.

[0117] Although the embodiments of the present disclosure have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present disclosure, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A cardiac CT imaging control method, characterized in that: include: In response to a start signal of the first scanning phase, after adjusting the collimator of the cardiac CT imaging device to a narrow opening working mode and the exposure current to a low exposure dose mode, the cardiac CT imaging device collects projection data of a central cross section of the heart corresponding to different times in the first scanning phase, and then determines an exposure time corresponding to an optimal phase in the second scanning phase based on the projection data; The method of determining the exposure time corresponding to the optimal phase in the second scanning stage based on the projection data includes: performing image reconstruction according to the projection data of the central cross section of the heart corresponding to each time to obtain a multi-phase reconstructed image of the central cross section of the heart; determining the similarity between each group of adjacent images in the multi-phase reconstructed image; establishing an image difference feature change curve based on the similarity, wherein the abscissa of the image difference feature change curve is time and the ordinate is the similarity; determining the heart movement cycle and the optimal phase based on the image difference feature change curve, wherein the optimal phase is configured to be equal to the phase of the last minimum point in the image difference feature change curve; determining the exposure time and exposure duration of the second scanning stage based on the heart movement cycle and the optimal phase; In response to the start signal of the second scanning phase, after the collimator is adjusted to the large opening working mode and the exposure current is adjusted to the high exposure dose mode, the projection data of the heart corresponding to the exposure moment in the second scanning phase is collected by the cardiac CT imaging device, and then the first reconstructed image of the heart at the optimal phase is determined based on the projection data.

2. The method according to claim 1, characterized in that In the narrow opening working mode, the radiation source of the cardiac imaging device is configured to irradiate the central cross section of the heart; in the wide opening working mode, the radiation source is configured to irradiate the entire heart; and, The scanning duration of the first scanning phase includes at least one complete heartbeat cycle.

3. The method according to claim 2, characterized in that After adjusting the collimator of the cardiac CT imaging device to a narrow opening working mode and the exposure current to a low exposure dose mode, the cardiac CT imaging device is used to collect projection data of the central cross section of the heart corresponding to different times in the first scanning phase, including: Adjusting the width of the shielding opening of the collimator to a set value so that the radiation range of the radiation source covers the entire central cross section of the heart; The exposure current is set according to a pre-selected image quality parameter; wherein the exposure current is a minimum exposure dose based on satisfying the image quality parameter; selecting a scan duration of the first scan phase and the different times for data acquisition; The projection data of the heart center cross section corresponding to each of the different times are collected by the heart CT imaging device.

4. The method according to claim 1, characterized in that The different times of the first scanning stage are distributed at equal intervals, and the first scanning stage and the second scanning stage both adopt a wide-body tomographic prospective cardiac scanning mode; and the method further includes: In the second scanning stage, the cardiac CT imaging device also collects projection data of the heart corresponding to other preset moments in the exposure duration except the exposure moment, and image reconstruction is performed based on the projection data corresponding to the exposure moment in the second scanning stage and the other preset moments, and the reconstruction result corresponding to the minimized image artifacts is selected as the second reconstructed image of the heart at the optimal phase.

5. The method according to claim 1, characterized in that The cardiac motion cycle is configured to be equal to the distance between adjacent minimum value points or the distance between adjacent maximum value points in the image difference characteristic change curve; and, The exposure time T3 and exposure duration P of the second scanning stage exp They are configured as: T3 = P Send + ⌈(max(T now - T2,T prepare ) + T shift ⌉×P range - T shift P exp = 2×T shift in, T shift = R / 2×(180+Fan) / 360) / P range + DeltaT Where P Send is the time when the optimal phase is located, T now is the current moment, T2 is the exposure end moment of the first scanning stage, T prepare is the fixed response time required for the hardware of the cardiac CT imaging device to switch from the narrow opening working mode to the large opening working mode, P range is the cardiac cycle, T shift To reconstruct an image, the cardiac CT imaging device needs to consume half of the data acquisition time, DeltaT is the redundant time, R is the time taken for the scanning gantry in the cardiac CT imaging device to rotate one circle, and Fan is the opening angle of the detector in the cardiac CT imaging device.

6. A cardiac CT imaging control device for implementing the cardiac CT imaging control method according to any one of claims 1 to 5, characterized in that: include: a first control unit configured to, in response to a start signal of the first scanning phase, adjust the collimator of the cardiac CT imaging device to a narrow opening working mode and the exposure current to a low exposure dose mode, and then collect projection data of a central cross section of the heart corresponding to different times in the first scanning phase through the cardiac CT imaging device, and then determine an exposure time corresponding to an optimal phase in a second scanning phase based on the projection data; The second control unit is configured to respond to the start signal of the second scanning stage, adjust the collimator to a large-opening working mode and the exposure current to a high exposure dose mode, and then collect projection data of the heart corresponding to the exposure moment in the second scanning stage through the cardiac CT imaging device, and then determine a first reconstructed image of the heart at the optimal phase based on the projection data.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the cardiac CT imaging control method according to any one of claims 1 to 5.

8. A cardiac CT imaging device, characterized in that: The cardiac CT imaging device includes: a radiation source, a detector, a collimator, a scanning gantry, at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor executes the cardiac CT imaging control method described in any one of claims 1 to 5.

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