Flat-panel CT machine

Abstract

The present invention provides a flat-panel CT machine, including a ray emitter and a flat-panel detector, which adopts 360° scanning or 180° scanning. The flat-panel detector uses a larger length and width than the flat-panel detector used for DSA, can cover a single part of the human body, and no longer needs spiral scanning; the scanning time is greatly reduced, which can effectively reduce motion artifacts; the radiation dose of the patient is greatly reduced; the spatial resolution and the number of longitudinal scanning layers are greatly improved, and it is a gapless scanning. The pulse control technology of X-ray emission is adopted to make the data obtained by the CT machine complete and without missing, and the image is clearer. Through pulse control technology or 180° scanning mode, the scanning frequency is reduced by half; pulse control technology can reduce the requirement for the mobility of the detector thin film transistor by about 10 times; by redesigning the number of detector array elements to further reduce the frequency, and control the inverter frequency of the ray emitter within an achievable range, the CT machine has the possibility of practical application.

Description

Technical Field

[0001] The present invention relates to the technical field of CT equipment, and in particular to a flat-panel CT machine. Background Art

[0002] CT (Computed Tomography) is an electronic computer tomography. The basic principle of existing CT imaging is to use an X-ray beam to scan a layer of a certain thickness of the human body. The detector receives the X-rays that pass through the layer, converts them into visible light, and then converts them into electrical signals by the photoelectric converter. Then, they are converted into digital signals by the analog / digital converter and input into the computer for processing. The image formation process is like dividing the selected layer into a number of rectangular blocks of equal volume, called voxels. The information obtained from the scan is calculated to obtain the X-ray attenuation coefficient or absorption coefficient of each voxel, and then arranged into a matrix, namely a digital matrix. The digital matrix can be stored in a disk or CD. The digital / analog converter converts each number in the digital matrix into small squares of varying grayscales from black to white, namely pixels, and arranges them in a matrix to form a CT image. The core of this is the CT machine detector and ray emitter.

[0003] Existing CT machines use bulky CT-specific detectors, most of which are made of rare earth ceramics and are arc-shaped. The detector structure consists of rows of detectors distributed side by side (with corresponding photoelectric conversion circuits and analog-to-digital conversion circuits underneath). The number of rows has developed from the initial single row to the current mainstream 128 rows (with some 256 rows or 320 rows), and the number of effective detection units in each row is less than 900.

[0004] The existing CT machines have the following objective disadvantages:

[0005] 1. The number of detector rows is limited, so the range of 360° rotation scanning is relatively narrow (the widest vertical detector is currently 160mm, which can basically meet the single-circle scanning requirements of small parts, but still cannot meet the single-circle scanning requirements of large parts). Multiple spiral scans are required to complete a part. The bed is moving during scanning, which is prone to motion artifacts.

[0006] 2. Because of spiral scanning, the image of 360° scanning is not a true cross-sectional section, but a cross-sectional image with a certain layer thickness that is not on the same section. Although the current 256-row can achieve a layer thickness of 625um (the thinnest is 400um), it is not an isometric image after all; there is an inter-layer gap. Although the current 256-row can also give an inter-layer gap image of 625um (the thinnest is 400um) thick through the algorithm, it is not a real image after all. There is a possibility of missing the detection of extremely subtle lesions in the early stage.

[0007] 3. The scanning time is long and the radiation dose to the patient is also large. Because multiple scans are required, the time is long and the radiation dose to the patient is also increased.

[0008] 4. The spatial resolution is low and the reconstructed image pixels are not high. The highest resolution is less than 24Lp / cm, and the reconstructed image pixels are generally 512*512 or 1024*1024.

[0009] In view of the above defects of existing CT machines, many manufacturers have tried to apply flat-panel detectors to CT machines. However, the maximum single-side size of medical flat-panel detectors used for DR and DSA on the market is 17 inches (about 43cm), which can fully meet the use requirements, but if they are applied to flat-panel CT machines, the size is still too small, and the abdomen and chest cannot be included in the scanning range in the horizontal direction; when the current flat-panel detectors are applied to CT machines, the requirements for scanning frequency and thin-film transistor mobility are too high, but in reality, the frequency and thin-film transistor mobility of flat-panel detectors are generally still very low and cannot meet the requirements of CT machines. The above problems have not been solved so far. Except for CBCT, there is no flat-panel CT machine suitable for whole-body scanning on the market. Summary of the invention

[0010] The purpose of the present invention is to solve at least one problem existing in the prior art to a certain extent, and to provide a flat-panel CT machine with fast scanning speed, more realistic images, better image quality, avoidance of missed detection, and more complete functions. The technical solution is as follows:

[0011] A flat-panel CT machine, wherein the scanning frame comprises a frame, a rotating device, a ray emitter and a flat-panel detector, and other components for providing support, drive, cooling, power supply, control, data transmission and processing, positioning, etc. for the above components; the rotating device is arranged in the frame, the ray emitter and the flat-panel detector are relatively arranged in the rotating device and can be driven by the rotating device to make synchronous motion on a coaxial circle;

[0012] The ray emitter adopts 360° scanning or 180° scanning;

[0013] The length of the flat-panel detector in the direction perpendicular to the axis of its circular motion is greater than 17 inches (usually more than 25 inches), and can include the widest part of the human body in the direction of shoulder width within the scanning range; the width in the direction of the axis of its circular motion (usually more than 25 inches) can include a single part of the human body (except limbs), and the examination bed does not need to be moved during the scanning of any single part.

[0014] As a further optional solution of the flat panel CT machine, when the ray emitter adopts a 360° scanning mode, the ray emitter adopts a pulse control mode, a pulse modulation circuit is provided in the control circuit of the ray emitter, and the reading pulse signal of the flat panel detector is modulated by the pulse modulation circuit and used to control the ray emitter to emit rays;

[0015] The pulse signal for controlling the ray emitter to emit rays has the same frequency as the pulse signal for reading from the flat panel detector, but has opposite phases;

[0016] The rays emitted by the ray emitter are dual-frequency X-rays (high frequency + low frequency) whose high-frequency part frequency under the control of the flat-panel detector reading pulse signal is much higher than the detector reading frequency. The ray emitter emits rays when the flat-panel detector collects data and does not emit rays when the flat-panel detector reads.

[0017] As a further optional solution of the flat-panel CT machine, the pulse signal for controlling the ray emitter to emit rays and the pulse signal for reading the flat-panel detector are both square wave pulse signals with equal widths in high and low potential time axes.

[0018] As a further optional solution of the flat-panel CT machine, under the control of the operating table computer, the pulse signal for controlling the ray emitter to emit rays and the pulse signal for controlling the flat-panel detector to read rays need to be inverted respectively in the first 180° and the last 180° of the rotational scanning of the ray emitter and the flat-panel detector.

[0019] As a further optional solution of the flat-panel CT machine, when the ray emitter adopts a 180° scanning mode, the scanning frame includes a C-arm structure; the ray emitted by the ray emitter is a high-frequency X-ray with a frequency much higher than the reading frequency of the flat-panel detector, and the ray emitter continuously emits rays during the collection and reading process of the flat-panel detector.

[0020] As a further optional solution of the flat-panel CT machine, a flat-panel CT machine that scans in a ray pulse control mode or a flat-panel CT machine that scans in a 180° mode needs to be redesigned when the flat-panel detector is limited by the reading frequency: when the flat-panel CT machine adopts a 4K projection matrix value, the number of detector units in each row of the flat-panel detector is 1634, and the number can fluctuate within the range of ±5%; when the flat-panel CT machine adopts an 8K projection matrix value, the number of detector units in each row of the flat-panel detector is 2312, and the number can fluctuate within the range of ±5%; when the flat-panel CT machine adopts a 16K projection matrix value, the number of detector units in each row of the flat-panel detector is 3269, and the number can fluctuate within the range of ±5%.

[0021] As a further optional solution of the flat-panel CT machine, the ray emitter adopts a 360° scanning mode and the rays emitted by the ray emitter are high-frequency X-rays with a frequency much higher than the detector reading frequency. When the ray emitter continuously emits rays during the acquisition and reading process of the flat-panel detector, the flat-panel detector needs to be redesigned when it is limited by the reading frequency: when the flat-panel CT machine adopts a 4K projection matrix value, the number of detector units in each row of the flat-panel detector is 1156, and the number can fluctuate within the range of ±5%; when the flat-panel CT machine adopts an 8K projection matrix value, the number of detector units in each row of the flat-panel detector is 1634, and the number can fluctuate within the range of ±5%; when the flat-panel CT machine adopts a 16K projection matrix value, the number of detector units in each row of the flat-panel detector is 2312, and the number can fluctuate within the range of ±5%.

[0022] As a further optional solution of the flat panel CT machine, the flat panel CT machine further includes a cooling device, which is arranged at the bottom of the flat panel detector and can rotate synchronously with the flat panel detector;

[0023] When the flat panel CT machine adopts a 360° scanning scanning method, the cooling device adopts a semiconductor refrigeration method.

[0024] As a further optional solution of the flat-panel CT machine, a plurality of positioning lights are provided on the scanning frame of the flat-panel CT machine, and the positioning lights project at least two laser positioning lines falling in the shoulder width direction, which are used for forward and rear positioning of the scanning part so that the scanning part is positioned within the maximum detection range of the flat-panel detector.

[0025] As a further optional solution of the flat panel CT machine, a counterweight block for balancing the weight of the flat panel detector and the ray emitter is provided on the rotating device located below the flat panel detector.

[0026] As a further optional solution for the flat-panel CT machine, as the width of the flat-panel detector increases, that is, the width in the direction in which the examination bed enters and exits the frame increases, the width of the emission window of the corresponding ray emitter in this direction also needs to be increased and matched with the width of the flat-panel detector, which can be achieved by a beam limiter; similarly, the width of the rotating device and the frame in the direction in which the examination bed enters and exits the frame also needs to be increased accordingly.

[0027] As a further optional solution of the flat-panel CT machine, the flat-panel CT machine includes, in addition to the scanning frame, a power cabinet, an examination bed, an operating table computer, an image workstation, etc. Due to the substantial increase in the image pixels and scanning layers of the flat-panel CT machine, as well as the substantial increase in the functions, the computing power and storage capacity of the operating table computer and the image workstation also need to be substantially increased accordingly.

[0028] The flat panel CT machine of the present invention has at least the following advantages:

[0029] Flat-panel CT machines use the medical dynamic flat-panel detectors used for DSA to replace existing CT detectors. Flat-panel detectors are longer than those used for DSA (in the direction of human shoulder width, greater than 17 inches) and wider than existing CT detectors (in the direction of human height). They can cover a single part of the human body (except for the limbs). Scanning a single part only requires scanning 360° or 180° (except for the limbs), and spiral scanning is no longer required. During scanning, the bed no longer needs to move forward and backward, and the scanning time is greatly reduced, which can effectively reduce motion artifacts. The radiation dose to patients is greatly reduced. The spatial resolution and the number of longitudinal scanning layers are greatly improved, and it is a gapless scan to ensure that no missed inspections are made.

[0030] The positioning function can be achieved through the positioning lamp, and the scanning of the positioning film is no longer necessary, which saves working time and reduces the patient's radiation dose.

[0031] At the same time, in the 360° scanning mode, a pulse modulation circuit is added to the control circuit of the ray emitter, and the flat-panel detector reading pulse signal is used to control the output of the ray. In this way, the originally high-frequency (relative to the reading frequency of the flat-panel detector) ray is controlled by a low-frequency signal (that is, a pulse signal), and the pulse signal frequency is variable. The ray control pulse signal frequency of the ray emitter is consistent with the reading frequency of the flat-panel detector, but the phase is opposite, so that when the ray emitter emits rays, the flat-panel detector only collects data but does not read it, and does not emit rays when reading. Both signals are square wave pulse signals with equal width on the high and low potential time axes, so that the collected data is complete and without missing, the obtained data is more real, and the image is clearer.

[0032] Optimize the working scheme of the ray emitter to emit rays, and use the technology of two pulse modulation signals with opposite phases when scanning the last 180 degrees and the first 180 degrees, so as to avoid the loss and duplication of reading data and ensure the accuracy of projection data. Most importantly, by using the above pulse control technology in the 360° scanning mode, or using the 180° scanning mode, the flat-panel CT machine can reduce the scanning frequency (also called reading frequency) of the flat-panel detector by half compared with the existing 360° scanning mode of the CT machine; when the ray pulse control technology is used, the requirements for the mobility of the detector transistor can be reduced by about 10 times due to the maximum extension of the reading time, making the application of the flat-panel CT machine easier to realize from a technical point of view, reducing the manufacturing cost and use cost of the flat-panel detector, and greatly reducing the heat dissipation requirements of the detector.

[0033] Since a 180° scanning mode can be adopted, the scanning frame of the flat-panel CT machine can be made into various forms of C-arm structures, which can be fixed or movable to meet various operating environment conditions or cost requirements.

[0034] At the same time, a solution to the practical problem is given: when the flat-panel CT machine is limited by the reading frequency of the flat-panel detector, the requirement for the reading frequency of the flat-panel detector is reduced by redesigning the number of detection units (also called the number of array elements) of the flat-panel detector, and the requirement for the inverter frequency of the ray emitter is also reduced, making the application of the flat-panel CT machine easier to realize, and further reducing the manufacturing cost and use cost of the flat-panel detector, and further reducing the heat dissipation cost of the detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A schematic diagram of the scanning frame structure of a flat-panel CT machine provided in an embodiment of the present invention is shown.

[0037] Description of main component symbols:

[0038] 1- scanning frame; 11- frame; 111- inner hole; 12- ray emitter; 13- flat panel detector; 14- rotating device; 15- cooling device. DETAILED DESCRIPTION

[0039] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0040] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0044] Example 1

[0045] like Figure 1 As shown, this embodiment provides a scanning frame 1 of a flat-panel CT machine, including a frame 11, a ray emitter 12, a flat-panel detector 13, a rotating device 14 and a cooling device 15.

[0046] An inner hole 111 is formed on the frame 11 . The ray emitter 12 and the flat panel detector 13 are relatively arranged in the rotating device 14 and can be driven by the rotating device 14 to make a circular motion along the axis of the inner hole 111 .

[0047] In this embodiment, the flat-panel CT machine adopts a 360° scanning mode, and the general structure of its scanning frame 1 is similar to that of the existing third-generation CT machine. In other embodiments, the flat-panel CT machine can also adopt a 180° scanning mode. In this case, its scanning frame 1 can be made into various C-arm structures in addition to being made into a structure similar to that of a traditional CT machine.

[0048] In this embodiment, the scanning frame 1 is the main body of the flat-panel CT machine. The frame 11 is based on the base and is used to install and carry other components. Various power boxes, drive motors, wireless transmitting and receiving devices, various cables, carbon brushes, rotating anode starting circuits, KV and mA control circuits, inverter circuits, and laser lights that provide positioning for scanning are arranged in the frame 11, and the rotating device 14 is also carried by it through the rotating shaft.

[0049] The inner hole 111 is formed on the frame 11, and is used for the inspection bed to carry the inspected object in and out of the scanning frame. The ray emitter 12 emits rays toward the inner hole 111, and the detection surface of the flat panel detector 13 faces the inner hole 111. The ray emitter 12 can generate X-rays. The flat panel detector 13 is used to receive the remaining X-ray amount generated by the ray emitter 12 after being absorbed by the inspected object, and convert the X-rays into electrical signals, and then convert them into digital signals through analog-to-digital conversion. The cooling device 15 is used to cool the flat panel detector 13. The rotating device 14 is used to carry the ray emitter 12, the flat panel detector 13 and the cooling device 15, so that they rotate as a whole.

[0050] The rotating device 14 is connected to the frame 11 through a rotating shaft. The frame 11 is provided with a driving device for driving the rotating device 14 to rotate. The rotating device 14 drives the ray emitter 12, the flat panel detector 13 and the cooling device 15 to rotate coaxially and synchronously around the axis of the inner hole.

[0051] The flat panel detector 13 may be formed by splicing flat panel detector modules, or may be formed by a whole plate (which needs to be redesigned).

[0052] Since most of the existing 17-inch flat panel detectors used in DSA are made of 4 flat panels (there are also whole panels, but the pixels are much lower), and the images at the joints are processed by software, the simple way is to splice 2 more panels (forming a 2*3 structure, reaching 17*26 inches) or 4 more panels (forming a 2*4 structure, reaching 17*43 inches) or 5 more panels (forming a 3*3 structure, reaching 26*26 inches) or 8 more panels (forming a 3*4 structure, reaching 26*34 inches) or 12 more panels (forming a 4*4 structure, reaching 34*34 inches) on the basis of the original 4 panels, or use panels of other sizes to splice to form panels of various specifications, which is technically easy to implement and the pixels can also be increased. However, this splicing method is difficult to implement in reality because the number of units in each row of the detector is too large and the requirement for the detector reading frequency is too high. Taking a 26-inch (actually 25.5-inch) long flat panel detector 13 (about 154um detection unit side length, about 4205 units per row) as an example, the maximum meaningful effective projection matrix value that can be obtained is 7451*7451; the pixels of the reconstructed image that can be obtained are about 5268*5268; under the existing CT scanning mode, if a 17-inch object is scanned 360° in 1 second, the required scanning frequency is about 13204Hz; if a 17-inch object is scanned 360° in a minimum time of 0.5 seconds, the required scanning frequency is about 26407Hz; if a 17-inch object is scanned 360° in a minimum time of 0.3 seconds, the required scanning frequency is about 44012Hz (equivalent to each acquisition and reading cycle of only 22.7us, the time allocated to the detector reading is ≤2.3us, and the mobility of the thin film transistor is required to be not less than 440cm 2 / (V·s)), which places too high requirements on the scanning frequency of the flat-panel detector and the mobility of the thin-film transistor, and is difficult to achieve in practical applications.

[0053] Therefore, in reality, it is necessary to redesign the array element structure of the flat-panel detector (see below for details) to reduce the requirement for the reading frequency by reducing the number of array elements.

[0054] The size of the flat panel detector 13 can be determined according to the needs of the manufacturer. Generally, the length of the flat panel detector 13 in the direction perpendicular to the axis of its circular motion is determined by the ray emission angle of the ray emitter 12, the diameter of the inner hole 111 of the center of the frame 11 entering and exiting the examination bed, and the diameter of the rotating device 14, so as to meet the scanning in the direction of the human shoulder width; the width of the flat panel detector 13 in the direction of its circular motion is determined by the width of the rotating device in the direction of the axis of its circular motion, but it is necessary to meet the scanning of a single part (except the limbs) in the direction of the human body height. The length of the flat panel detector 13 is roughly the chord length corresponding to the arc where the effective detection unit array of the arc detector of the existing CT machine is located, in order to ensure that the scanning of the widest body part of a patient with a large body size is included in the measurable range of the detector. For example, the length of the flat panel detector 13 is 26 to 34 inches and the width is 26 to 34 inches, but it is not limited to this size, and it can preferably be 26*26 inches.

[0055] In this embodiment, the length of the flat panel detector 13 in the direction perpendicular to the axis of its circular motion is selected to be 26 inches, and the width is selected to be 26 inches.

[0056] Various materials can be selected for the flat panel detector 13. In this embodiment, the flat panel detector 13 uses oxide thin film transistors (Oxide TFT) or low temperature polysilicon thin film transistors, because the transistor mobility of these two materials is relatively high and can meet the high frequency requirements of CT scanning.

[0057] The rotating device 14 is in a ring shape, and the ray emitter 12 and the flat panel detector 13 are relatively arranged in the rotating device 14, and are driven by the rotating device 14 to rotate relative to the frame 11. The ray emitter 12 and the flat panel detector 13 need to be powered to work, but at the same time, they need to rotate, so as to perform a circumferential scan of the human body.

[0058] In this embodiment, a 360° scanning method is adopted, and the power transmission method of the rotating device 14 is designed to be a slip ring. There are many mutually insulated conductive rings on the rotating device 14. Electrical connection contacts with the rotating device 14, such as carbon brushes, are arranged in the frame 11 to form a rotating electrical connection with the conductive rings on the rotating device 14, and the power provided to the ray emitter 12, the flat panel detector 13 and the cooling device 15 in the frame is transmitted to the conductive rings in the rotating device 14. The conductive rings of the rotating device 14 transmit electricity to the ray emitter 12, the flat panel detector 13 and the cooling device 15, so as to supply power to the ray emitter 12, the flat panel detector 13 and the cooling device 15.

[0059] In other embodiments, the conductive device in the rotating device 14 can also be designed as a power transmission method used in old non-spiral CT machines: the power supply and various controls and data are directly connected to the ray emitter 12 and the flat panel detector 13 (and the cooling device 15) through cables. This method is more suitable for flat panel CT machines using a 180° scanning method, and is suitable for making the scanning frame into various C-arm structures, which can reduce costs.

[0060] In this embodiment, the reading pulse signal of the flat panel detector 13 and the digital signal of the collected projection data, as well as the temperature data and control signal of the cooling device 15, all communicate with the wireless receiving and transmitting device in the rack 11 through their respective wireless communication modules, and are then transmitted to the operating table computer through optical cables.

[0061] The frame 11 is formed with a circular inner hole 111 coaxial with the rotating device 14 for the inspected object to enter and exit the frame 11. The ray emitter 12 emits rays toward the inner hole 111, and the detection surface of the flat panel detector 13 faces the inner hole 111. The diameter of the inner hole 111 is not less than 17 inches.

[0062] The flat panel CT further includes an examination bed, which moves in a direction parallel to the axis of the inner hole 111 .

[0063] The flat panel CT machine also includes a cooling device 15, which is used to cool the flat panel detector 13 and control the working temperature of the flat panel detector 13 to a suitable temperature. The flat panel detector 13 made of amorphous silicon flat panel material requires an operating temperature of about 17 degrees Celsius. Currently, the dynamic flat panel cooling applied to DSA is mostly water cooling, and the cooling host is placed in a control cabinet and connected to the flat panel detector by two water pipes. This cannot be applied to the CT machine with the rotating device 14 in the form of a slip ring in this embodiment.

[0064] In this embodiment, the cooling device 15 is integrated into the rotating device 14. The refrigeration unit of the cooling device 15 is arranged at the bottom of the flat panel detector 13. The cooling device 15 can rotate synchronously with the ray emitter 12 and the flat panel detector 13, and the relative position with the flat panel detector 13 is fixed.

[0065] The cooling device 15 can be used in any of the following ways: semiconductor refrigeration, compressor plus refrigerant refrigeration, ammonia refrigeration, etc. The power supply is also obtained from the conductive ring of the rotating device 14.

[0066] In this embodiment, the cooling device 15 is a semiconductor refrigeration method. The working principle of semiconductor refrigeration is based on the Peltier principle. When direct current passes through a couple formed by two different semiconductor materials in series, heat can be absorbed and released at both ends of the couple, respectively, so as to achieve the purpose of refrigeration. It is a refrigeration technology that produces negative thermal resistance, and its characteristics are that there are no moving parts, the refrigeration speed is fast, and the reliability is relatively high. The cooling device 15 adopts the semiconductor refrigeration method. The cold and hot ends of its refrigeration unit are both made of alloy heat sinks with good thermal conductivity, and the middle is coated with thermal conductive silicone grease. The alloy heat sink plays the role of heat dissipation and also plays the role of fixing the flat panel detector 13 and the cooling device 15, and is fixed to the base on the rotating device 14 through the heat sink; the bottom of the flat panel detector is directly fixed on the cold end alloy heat sink (coated with thermal conductive silicone grease) of the refrigeration unit of the cooling device 15; the hot end of the refrigeration unit of the cooling device 15 adopts fan heat dissipation, and several rows of fans are connected in parallel, and the fan is fixed on the alloy heat sink at the hot end. The power supply of the fan comes from the control unit of the cooling device 15 (mentioned below), and the speed of the fan is also controlled by it.

[0067] Furthermore, the cooling device 15 includes a control unit, and a temperature sensing unit and a refrigeration unit electrically connected to the control unit. The control unit is arranged at a suitable position of the rotating device 14, and provides power and control for the entire cooling device 15. Its own power comes from the rotating device 14 (electric ring on the slip ring). The temperature sensor unit includes at least 6 temperature sensors, which are evenly arranged at the cold end of the cooling device 15 and close to (preferably embedded in) the heat dissipation alloy member of the flat panel detector 13, and are used to sense the temperature of each point of the flat panel detector 13 to ensure that the temperature of the entire flat panel detector 13 is consistent; a wireless communication module is provided on the control unit, and the temperature sensor transmits the sensed temperature of the flat panel detector 13 to the wireless transmitting and receiving device on the rack 11 through the wireless communication module, and then transmits it to the operating table computer through the optical cable, and the operating table computer sends the control signal to the control unit through the wireless communication module; when the temperature sensor senses that the temperature of any part of the flat panel detector 13 is not within the preset temperature range, the controller controls the refrigeration unit to adjust the refrigeration efficiency, if the sensed temperature is higher than the target temperature, the refrigeration efficiency is increased, and if the sensed temperature is equal to the target temperature, the refrigeration efficiency of the refrigeration unit is maintained. The display screen of the console computer can display the temperature of each part of the flat panel detector 13 in real time. If the temperature of the flat panel detector 13 is 2 degrees Celsius higher than the temperature set by the console computer, or the temperature of any temperature sensing point is 2 degrees Celsius higher than the other sensing points, the console computer will issue a temperature error alarm.

[0068] The flat panel detector 13 can have different temperature standards in the standby state and the working state. For example, the temperature of the flat panel detector 13 can be controlled at about 25 degrees Celsius in the standby state, and the temperature of the flat panel detector 13 can be controlled at 17 degrees Celsius in the working state to achieve the effect of energy saving and consumption reduction.

[0069] The ray emitter 12 and the flat-panel detector 13 on the rotating device 14 are arranged opposite to each other, and the weight of the emitting side and the opposite receiving side are required to be equal, and the center of gravity of the two is on the same diameter line of the same circle, and the circle is concentric with the center circle of the rotating device 14 to ensure the rotational balance of the rotating device 14.

[0070] Since the weight of the ray emitter 12 (including the tube and the high-pressure oil tank) is greater than the sum of the weights of the flat panel detector 13 and the cooling device 15, a counterweight is provided on the rotating device 14 at the center line of the flat panel side for accurate counterweighting to ensure the balance of the rotating device 14 during rotation. To reduce the overall weight, the two high-pressure oil tanks in the ray emitter 12 can be symmetrically arranged as close as possible to both sides of the flat panel detector 13 to reduce the weight of the counterweight.

[0071] The flat panel detector 13 used in the flat panel CT machine of this embodiment is a flat panel detector. In other embodiments, the flat panel detector 13 is also made into an arc shape, which can effectively solve the problem that the photoelectric conversion efficiency may be reduced due to the two sides of each row of the flat panel detector cannot receive rays vertically, and the image quality will be better.

[0072] In this embodiment, by increasing the number of positioning lights on the frame 11, the number of laser positioning lines projected by the positioning lights and falling in the shoulder width direction is increased to 3, which are used to position the scanning part in the front, middle and back, so that the scanning part is positioned within the maximum detection range of the flat-panel detector 13. Since the flat-panel CT machine no longer needs spiral scanning, the positioning function of the scanning part can be realized by the positioning lights, so that the flat-panel CT machine no longer needs to scan the positioning film.

[0073] As the width of the flat panel detector 13 increases, that is, the width in the direction of the examination bed entering and exiting the frame increases, the width of the emission window of the corresponding ray emitter 12 in this direction also needs to be increased and match the width of the flat panel detector 13, which can be achieved by a beam limiter; similarly, the width of the rotating device 14 and the frame 11 in the direction of the examination bed entering and exiting the frame also needs to be increased accordingly.

[0074] In addition to the scanning frame 1, the flat panel CT machine also includes components such as a power cabinet, an examination bed, an operating table computer, and an image workstation. Due to the significant increase in image pixels and scanning layers, as well as the significant improvement in functions of the flat panel CT machine, the requirements for the computing power and storage capacity of the corresponding computer will also increase.

[0075] This embodiment also improves the control method of the ray emitter 12 for emitting rays.

[0076] When the existing CT machine is scanning, the radiation device emits high-frequency X-rays (relative to the reading frequency of the flat panel detector 13, much higher than the reading frequency of the flat panel detector 13), and continuously emits radiation during the entire 360° scanning process. Since the number of array elements per row of the existing CT machine detector is small, the number of projection matrices that can be obtained is small. It is necessary to complete the 360° scanning at a high scanning frequency to obtain the maximum effective projection matrix, thereby obtaining a maximum of about 1K image pixels. This is why the existing CT machine completely scans 360°.

[0077] However, for the flat-panel detectors used in existing DSAs, the number of array elements in each row is too high, and the reading frequency requirement for the flat-panel detector is too high, which is difficult to achieve in practice, thus limiting the application of flat-panel detectors in CT machines. This is the main reason why there are no applicable flat-panel CT machines so far; at the same time, the too high projection matrix and image pixels are not yet usable. If the projection matrix and image pixels are reduced by half, very high image pixels can still be obtained, which provides a material basis for scanning under ray pulse control and 180° scanning. Both methods can reduce the scanning frequency by half, thereby obtaining half the projection matrix and image pixels under the existing CT scanning method; it also provides ideas for the subsequent redesign of the number of array elements of the flat-panel detector.

[0078] In order to reduce the scanning frequency of the existing CT machine detector by half and significantly reduce the requirements for the mobility of the detector transistor, in this embodiment, the ray emission of the ray emitter 12 of the flat-panel CT machine adopts pulse modulation (or gate control) technology. A pulse modulation circuit is added to the pre-stage control circuit of the existing CT machine ray emitter (for example, a field effect tube is installed in the main DC power supply part of the inverter circuit, and the detector reading pulse signal is inverted by an inverting circuit before reaching the gate of this field effect tube. The inverted signal becomes a ray pulse control signal to control the on and off of this field effect tube). The flat-panel detector 13 reading pulse signal issued by the operating table computer is used to control the output of the ray. In this way, the original high-frequency ray is controlled by the low-frequency signal (herein, the signal controlling the output of the ray is called the ray pulse modulation signal or the ray pulse control signal, which is obtained by inverting the flat-panel detector 13 reading pulse signal), and the low-frequency frequency is variable. The ray pulse modulation signal and the detector reading pulse signal are both square wave pulse signals with the same frequency but opposite phases. When the ray pulse modulation signal is at a high potential, the ray emitter emits rays, and the reading pulse modulation signal of the flat-panel detector 13 is at a low potential, and only data is collected but no reading is performed; when the ray pulse modulation signal is at a low potential, the ray emitter does not emit rays, and the reading pulse modulation signal of the flat-panel detector 13 is at a high potential, and reading is performed without collecting data; no reading is performed when rays are emitted, and no rays are emitted when reading is performed.

[0079] In this embodiment, the frequency of the ray pulse modulation signal is controlled by the reading pulse modulation signal of the flat panel detector 13; the frequency of the reading pulse modulation signal of the flat panel detector 13 is controlled by the projection matrix value and scanning time required in the scanning conditions of the operation table computer. The computer automatically gives a 5V square wave pulse signal (i.e., the reading pulse modulation signal of the flat panel detector 13) according to this frequency. The high and low potential time axes can be equal in width, or they can be inverted after scanning 180°, all of which are set by the software in the computer. The calculation formula of the reading pulse modulation signal frequency of the flat panel detector 13 is: X=Y / Z / T, where X is the reading pulse modulation signal frequency of the flat panel detector 13, Y is the projection matrix value required to be achieved, Z is the number of units in each row of the flat panel detector 13 (also called the number of array elements), and T is the time for scanning 360°.

[0080] In this embodiment, the reading pulse modulation signal of the flat panel detector 13 and the ray pulse modulation signal of the ray emitter 12 have the same frequency and opposite phases, and both adopt the design of equal width of the high and low potential time axis (that is, high potential time = low potential time), that is, the time when the ray emitter 12 emits rays is equal to the time when it does not emit rays, and the acquisition time of the flat panel detector 13 is equal to the reading time, so that the time when the ray emitter 12 emits rays is equal to the reading time of the flat panel detector 13. In this way, the reading time is extended to the maximum, thereby greatly reducing the requirements for the mobility of the detector transistor (reduced by about 10 times); at the same time, the acquisition time and the reading time are just the time when the outermost rotation distance of the detector is equal to the width of its array element, and data is collected once every array element width.

[0081] The present embodiment adopts a 360° scanning mode. To ensure that the flat-panel CT machine uniformly obtains the projection of each axis of the section during the 360° scanning, when the flat-panel detector 13 rotates to 180 degrees, the reading pulse modulation signal and the ray pulse modulation signal of the flat-panel detector 13 need to be inverted (opposite to the phase of the previous 180 degrees) to obtain the projection data of the axis that is missed due to the ray emitter not emitting rays and the flat-panel detector not collecting when the flat-panel detector 13 reads within the first 180-degree scanning range. Otherwise, the scanning data obtained by the subsequent 180-degree scanning is likely to repeat the data of the previous 180-degree scanning, and the missed data will still be missed.

[0082] Through this design, the time for collecting each array data is exactly the time when the array element rotation width is equal to its array element width, and the reading time is the same; no rays are emitted during reading, and the data during reading is the quantitative data at the end of the collection process, which is a complete and flawless projection matrix value, ensuring the authenticity of the data and the clarity of the image. A complete and non-repetitive image data is obtained when rotating one circle.

[0083] In this embodiment, according to the setting position of the radiation pulse modulation signal in the circuit and the delay characteristics of the subsequent circuit, it may be necessary to add a delay device in the flat-panel detector 13 reading pulse signal circuit to ensure that the time when the radiation pulse modulation signal arrives at the radiation emitter 12 is the same as the time when the flat-panel detector 13 reading pulse signal arrives at the flat-panel detector 13.

[0084] In other embodiments, the ray emission method of the existing CT machine can also be used: the ray emitted by the ray emitter 12 is a high-frequency X-ray, and the ray emitter 12 continuously emits rays during the process of collecting and reading the flat panel detector 13, requiring the reading time of the flat panel detector 13 to be quite short relative to its collection time, which can be almost ignored. In this case, a 180° scanning method can be used. Since only 180° is scanned, the scanning time is shortened by half, so that it can be scanned with half the detector reading frequency required for scanning 360° in the same time, thereby achieving the purpose of reducing the scanning frequency by half.

[0085] However, although the requirement for detector reading frequency of flat-panel CT machines has been reduced by half through radiation pulse control or 180° scanning, the frequency is still too high. In reality, in order to eliminate the artifacts of heart beats as much as possible, the scanning time requirement is very high (usually within 0.3 seconds). The shorter the scanning time, the higher the required scanning frequency, and the higher the requirement for the inverter frequency of the radiation emitter, making it difficult to find a suitable high-voltage inverter. Taking a 26-inch (actually 25.5-inch) long flat panel detector 13 (about 154um detection unit side length, about 4205 units per row) as an example, by scanning with a ray pulse control method or a 180° scanning method, the meaningful maximum effective projection matrix value that can be obtained is about 5268*5268; the reconstructed image pixels that can be obtained are about 3725*3725; if a 17-inch object is scanned 360° in 1 second, the required scanning frequency is about 7052Hz; if a 17-inch object is scanned 360° in 0.5 seconds, the required scanning frequency is about 14105Hz; if a 17-inch object is scanned 360° in 0.3 seconds, the required scanning frequency is about 23508Hz (equivalent to each acquisition and reading cycle of about 42.5us, the time allocated to the detector reading is about 21.3us, and the mobility of the thin film transistor is required to be not less than 47cm 2 / (V·s)), which can basically meet the requirements of the CT machine for the mobility of the thin film transistors of the flat panel detector, but the scanning frequency requirement for the flat panel detector is still too high. Because the higher the scanning frequency, the higher the high frequency requirement for the ray emitter 12, that is, the higher the frequency requirement for the high-voltage inverter, which needs to reach more than 230KHz, which is difficult to achieve with the existing technology. Therefore, it is necessary to reduce the scanning frequency of the detector by reducing the number of array elements per row to adapt to the existing inverter frequency.

[0086] Therefore, the number of array elements of the flat panel detector 13 needs to be redesigned.

[0087] For a flat-panel CT machine that scans in a ray pulse control mode or a flat-panel CT machine that scans in a 180° mode, the flat-panel detector 13 needs to be redesigned when it is limited by the reading frequency: 1. When a 4K projection matrix value is used, the number of detector units in each row can be designed to be 1634, and a fluctuation within the range of ±5% is allowed; 2K (1448*1448) reconstructed image pixels can be obtained; the required reading frequency of the flat-panel detector 13 is about 2565 Hz when the scan is completed in 1 second, about 5130 Hz when the scan is completed in 0.5 seconds, and about 8551 Hz when the scan is completed in 0.3 seconds. The above frequencies vary with the fluctuation of the number of units, and are also allowed to fluctuate within the range of ±5%. 2. When using 8K projection matrix values, the number of detector units in each row can be designed to be 2312, and it is allowed to fluctuate within the range of ±5%; 4K (2048*2048) reconstructed image pixels can be obtained; the required flat panel detector 13 reading frequency is about 3630Hz when the scan is completed in 1 second, about 7260Hz when the scan is completed in 0.5 seconds, and about 12100Hz when the scan is completed in 0.3 seconds. The above frequencies vary with the fluctuation of the number of units, and are also allowed to fluctuate within the range of ±5%. 3. When using 16K projection matrix value, the number of detector units in each row can be designed to be 3269, which is allowed to fluctuate within the range of ±5%; 8K (2896*2896) reconstructed image pixels can be obtained; the required reading frequency of the flat panel detector 13 is about 5132Hz when the scan is completed in 1 second, about 10265Hz when the scan is completed in 0.5 seconds, and about 17108Hz when the scan is completed in 0.3 seconds. The above frequencies vary with the fluctuation of the number of units, and are also allowed to fluctuate within the range of ±5%. The array element size of the flat panel detector 13 varies with the overall size of the flat panel detector 13, but they are all arranged evenly and without gaps; and each row of the entire detector is also arranged evenly and without gaps.

[0088] A flat-panel CT machine adopts the ray emitter working mode of an existing CT machine and scans 360°. The ray emitted by the ray emitter 12 is an X-ray with a frequency higher than the reading frequency of the flat-panel detector 13. The ray emitter 12 continuously emits rays during the acquisition and reading process of the flat-panel detector 13. When the flat-panel detector 13 is limited by the reading frequency, it needs to be redesigned: 1. When a 4K projection matrix value is adopted, the number of effective detection units in each row of the detector can be designed to be 1156, and it is allowed to fluctuate within the range of ±5%; 2K (1448*1448) reconstructed image pixels can be obtained; the required reading frequency of the flat-panel detector 13 is about 3630Hz when a circle scan is completed in 1 second, about 7260Hz when a circle scan is completed in 0.5 seconds, and about 12099Hz when a circle scan is completed in 0.3 seconds. The above frequencies vary with the fluctuation of the number of units, and are also allowed to fluctuate within the range of ±5%. 2. When using 8K projection matrix values, the number of detector units in each row can be designed to be 1634, and it is allowed to fluctuate within the range of ±5%; 4K (2048*2048) reconstructed image pixels can be obtained; the required flat panel detector 13 reading frequency is about 5131 Hz when completing a circle scan in 1 second, about 10262 Hz when completing a circle scan in 0.5 seconds, and about 17102 Hz when completing a circle scan in 0.3 seconds. The above frequencies vary with the fluctuation of the number of units, and are also allowed to fluctuate within the range of ±5%. 3. When using 16K projection matrix value, the number of detector units in each row can be designed to be 2312, and it is allowed to fluctuate within the range of ±5%; 8K (2896*2896) reconstructed image pixels can be obtained; the required reading frequency of the flat panel detector 13 is about 7260Hz when it completes a circle scan in 1 second, about 14519Hz when it completes a circle scan in 0.5 seconds, and about 24199Hz when it completes a circle scan in 0.3 seconds. The above frequencies vary with the fluctuation of the number of units, and are also allowed to fluctuate within the range of ±5%. The array element size of the flat panel detector 13 varies with the overall size of the flat panel detector 13, but they are all arranged evenly and without gaps; and each row of the entire detector is also arranged evenly and without gaps. From the above reading frequency, although the number of array elements is also reduced, under the conditions of the same pixels and the same scanning time, the flat panel detector 13 designed according to the existing scanning method requires a reading frequency much higher than the flat panel detector 13 in the flat panel CT machine scanned by the ray pulse control method or the flat panel CT machine with a 180° scanning method; the higher the pixel, the higher the required reading frequency, which limits its use in reality. Therefore, the flat panel CT machine that adopts the ray emitter working mode of the existing CT machine and scans 360° is difficult to be used in reality and is generally not recommended.

[0089] In this embodiment, a ray pulse control method is adopted to scan and redesign the flat panel detector: by adopting an 8K projection matrix value, the number of detector units in each row can be designed to be 2312; a 4K (2048*2048) reconstructed image pixel can be obtained; the required reading frequency of the flat panel detector 13 is about 3630 Hz when a 360° scan is completed in 1 second, about 7260 Hz when a 360° scan is completed in 0.5 seconds, and about 12100 Hz when a 360° scan is completed in 0.3 seconds, which is equivalent to a cycle of about 82.6 us for each acquisition and reading, and the time allocated to the detector reading is about 41.3 us, requiring the mobility of the thin film transistor to be not less than 24.2 cm 2 / (V·s), requiring the frequency of the IGBT of the high-voltage inverter to reach about 120~150KHz.

[0090] This embodiment is based on the overall structure and basic algorithm of the existing CT machine, and replaces the existing CT detector by applying a medical dynamic flat panel detector 13 for DSA that is similar but enlarged in size to the CT machine. DSA is the abbreviation of Digital Subtraction Angiography. Compared with the existing CT machine, the hardware changes of this flat panel CT machine include: replacing the detector and adjusting the hardware related to the flat panel detector 13 accordingly; adding a detector cooling device 15 so that the flat panel detector 13 can work normally even when running at high speed; improving the control method of ray emission, using pulse control technology, time axis equal width technology and 180 degree inversion technology, reducing the scanning frequency, and reducing the requirement for the mobility of the detector by about 10 times, so that a complete and defect-free image can be obtained, ensuring the clarity of the image.

[0091] Through the 360° scanning mode under the above pulse control (or the 180° scanning mode in other embodiments), the scanning frequency is reduced by half, and by redesigning the number of array elements of the flat-panel detector, the requirement for the reading frequency of the flat-panel detector is further reduced, making the flat-panel CT machine possible for practical application.

[0092] The number of positioning lights has been increased, so that the positioning function can be achieved through the positioning lights, and there is no need to do positioning film scanning; due to the significant increase in the image pixels and scanning layers of the flat-panel CT machine, as well as the significant improvement in functions, the requirements for the computing power of the corresponding computer will also increase. The software algorithm can be roughly the same, but it also needs to be adjusted accordingly. For example, when the fan beam back projection method in the filtered back projection algorithm (FBP) is used for image reconstruction, the equal angle FBP algorithm in the existing CT machine fan scanning is changed to an equal spacing FBP algorithm. This design does not involve the design of the corresponding software.

[0093] Through the above technologies, the performance and functions of flat-panel CT machines have been significantly improved.

[0094] The flat panel CT machine of this embodiment has the following technical effects:

[0095] 1. Greatly improve the performance of CT machines.

[0096] 1. Isometric images, more realistic data. Since the flat panel detector is relatively wide (Z-axis direction, i.e. the moving direction of the examination bed), reaching 26 to 34 inches, it can cover a single part of the human body (except the limbs). Any single part only needs to be scanned 360°, and spiral scanning is no longer required, which can make the cross-sectional image truly a cross-sectional image (also called isometric image), making the data more realistic.

[0097] 2. Reduce motion artifacts. During single-part scanning, the bed no longer needs to move forward and backward, eliminating motion artifacts caused by bed movement; and the single-part scanning time is greatly reduced (large-part scanning is increased from 1 to 5 seconds to 0.3 to 1 second), which can effectively reduce motion artifacts caused by involuntary movements such as patient breathing.

[0098] 3. High-pixel images can be obtained, and the spatial resolution is significantly improved. Taking a 26-inch (actually 25.5-inch) long flat-panel detector as an example, using an 8K projection matrix value, about 2312 units per row, and each detector unit side length of about 280um, its spatial resolution can reach more than 53Lp / cm (increases with the increase of the number of array elements); 4K (2048*2048) reconstructed image pixels can be obtained (increases with the increase of the number of array elements).

[0099] 4. No inter-layer gaps, ensuring no missed detection. Since the columns and rows of the flat-panel detectors are arranged in the same way, there are no gaps, and no spiral scanning is required, there are no inter-layer gaps. The layer thickness is reduced from the lowest 0.4mm of the existing CT machine to about 0.19mm (depending on the number of detector units, the lowest can reach about 100um), and the number of 360° scanning layers can be increased from the current maximum of 640 layers to more than 2312 layers (increasing with the increase in the number of array elements). The number of longitudinal (horizontal movement direction of the bed) scanning layers is greatly improved, which is a gapless scan to ensure no missed detection.

[0100] 5. Reduce radiation dose. Due to the significant reduction in scanning time and the use of time axis equal width pulse technology, only half of the time is spent on emitting radiation during scanning, and the radiation dose received by the patient is also greatly reduced, so that the radiation dose received by the patient is only about 1 / 10 of that of the existing CT machine, which is of great significance to the health of the person being examined.

[0101] 6. By using the above pulse control technology in a 360° scanning mode, or by using a 180° scanning mode, compared with the existing 360° scanning mode of a CT machine, a flat-panel CT machine can reduce the scanning frequency of the flat-panel detector by half, reduce the requirements for the reading frequency of the flat-panel detector, and greatly reduce the requirements for the mobility of the thin-film transistor (reduced by about 10 times), thereby reducing the manufacturing cost of the flat-panel detector; the load of the flat-panel detector is reduced by half, which will greatly extend its service life and reduce the cost of using the flat-panel detector; the heat generated by the flat-panel detector when working is greatly reduced, thereby reducing the energy consumption of the cooling device. By reducing the number of array elements of the flat-panel detector, the scanning frequency of the flat-panel detector is further reduced, and a high-voltage inverter that meets the inverter frequency requirements can be found under the existing technology for the ray emitter, thereby further reducing the manufacturing cost, use cost and heat dissipation power consumption of the flat-panel detector. Through the comprehensive application of the above technologies, CT machines have the possibility of practical application.

[0102] 7. The positioning function of the scanning part can be realized through the positioning light. The flat-panel CT machine no longer needs to scan the positioning film, which not only greatly saves working time and improves work efficiency, but also reduces the radiation dose of patients.

[0103] 8. The entire single-part scanning process only requires scanning 360° (or 180°), and the ray emitter using the ray pulse control method only emits rays for half of the time, which greatly reduces the workload of the ray emitter, greatly prolongs the service life of the ray emitter, and greatly reduces the cost of using the ray emitter (including the tube and high-pressure oil tank, of which the tube is an expensive consumable). At the same time, it greatly reduces power consumption, which is of great significance to energy conservation and emission reduction.

[0104] 2. Flat-panel CT scanning can directly obtain the real pixel data of each voxel in the three-dimensional space of the entire scanning area. The voxel is small enough (about 187um, and the minimum can reach 100um), and it is not necessary to perform complex algorithm calculations on the inter-layer gap to obtain image data like existing CT machines. It can be realized more quickly, realistically and accurately through software and greatly improve the functions of existing high-end CT.

[0105] 1. Clearer and richer tomographic images in any direction. As a rich set of voxel data can be obtained, tomographic images in any direction with extremely high pixels can be obtained, including oblique tomographic images at any angle, and any non-planar tomographic images of interest can also be obtained, and the images are clearer; the scanning frame no longer needs to be tilted to scan the cervical and lumbar vertebrae and other parts; when displayed as a movie, the image quality is higher, the layers are richer, and it can be viewed from any angle, not limited to the vertical and horizontal directions.

[0106] 2. More realistic and clearer perspective 3D images. The software can not only provide more realistic 3D images than existing CT, but also obtain clearer translucent stereoscopic images (called perspective 3D imaging, but it is more recommended to be called spatial 4D imaging because the image inside the box can be seen). When the window width and window position remain unchanged, the 4D images of the same tissue and the inside of the tissue in the scanning area can be rotated to observe. The 4D images of different tissues can also be observed by changing the window width and window position, so that the body structure and the location of the lesion can be seen at a glance. The lesion tissue and its lesion block can also be separated for 3D and 4D display. It is of great significance for clinicians to understand the condition more intuitively, for patients' families to understand the condition more easily, and for doctor-patient communication, and for teaching work.

[0107] 3. More accurate positioning function. Due to the real stereoscopic data with smaller voxels, more accurate clinical positioning can be achieved, which is helpful for formulating detailed surgical plans. After subsequent development, flat-panel CT can also be introduced into the operating room for precise minimally invasive surgery and applied to surgical navigation systems and robotic surgery.

[0108] 3. Flat-panel CT machines can also realize all the functions of DSA, DR (Digital Radiography) and digital gastrointestinal machines, and can meet all the functional requirements of general radiography, realizing multiple uses of one machine. It is of great significance for high-level hospitals with few patients or low-level hospitals or scientific research institutions with few special examination and treatment requirements.

[0109] Fourth, since a 180° scanning mode can be adopted, the scanning frame of the flat-panel CT machine can be made into various forms of C-arm structures, which can be fixed or movable to meet various operating environment conditions or cost requirements.

[0110] Therefore, a flat-panel CT machine is a flat-panel CT machine with fast scanning speed, more realistic images, better image quality, no missed detection, lower radiation dose, more complete functions, and a wider range of applications. It will enable CT machines to skip the era of row or layer classification and enter the flat-panel era. With the advent of the 5G era, especially the use of quantum computers in the future, it will make it easy to calculate and transmit complex and massive data in flat-panel CT machines, and also provide technical support for the practical application of flat-panel CT machines, and can use artificial intelligence for automatic pathological analysis and report issuance.

[0111] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0112] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A flat panel CT machine, characterized in that: The scanning frame comprises a frame, a rotating device, a ray emitter and a flat panel detector, wherein the rotating device is arranged in the frame, the ray emitter and the flat panel detector are arranged in the rotating device in a relative manner and can be driven by the rotating device to perform synchronous motion on a coaxial circle; The ray emitter adopts 360° scanning or 180° scanning; The length of the flat panel detector in a direction perpendicular to the axis of its circular motion is greater than 17 inches; When the ray emitter adopts a 360° scanning mode, the ray emitter adopts a pulse control mode, a pulse modulation circuit is provided in the control circuit of the ray emitter, and the reading pulse signal of the flat panel detector is modulated by the pulse modulation circuit to control the ray emitter to emit rays; The pulse signal for controlling the ray emitter to emit rays has the same frequency as the pulse signal for reading from the flat panel detector, but has opposite phases; The rays emitted by the ray emitter are dual-frequency X-rays whose high-frequency part frequency is higher than the detector reading frequency under the control of the flat-panel detector reading pulse signal. The ray emitter emits rays when the flat-panel detector collects data and does not emit rays when the flat-panel detector reads.

2. The flat panel CT machine according to claim 1, characterized in that: The pulse signal for controlling the ray emitter to emit rays and the pulse signal for reading the flat panel detector are both square wave pulse signals with equal widths in high and low potential time axes.

3. The flat panel CT machine according to claim 1, characterized in that: The pulse signal for controlling the ray emitter to emit rays and the pulse signal for reading the flat panel detector need to be inverted respectively in the first 180° and the last 180° of the rotational scanning of the ray emitter and the flat panel detector.

4. The flat panel CT machine according to claim 1, characterized in that: When the ray emitter adopts a 180° scanning scanning mode, the scanning frame includes a C-arm structure; the ray emitted by the ray emitter is an X-ray with a frequency higher than the reading frequency of the flat-panel detector, and the ray emitter continuously emits rays during the collection and reading process of the flat-panel detector.

5. The flat panel CT machine according to claim 1 or 4, characterized in that: When the flat-panel CT machine adopts 4K projection matrix value, the number of detector units in each row of the flat-panel detector is 1634, and the number can float within the range of ±5%; when the flat-panel CT machine adopts 8K projection matrix value, the number of detector units in each row of the flat-panel detector is 2312, and the number can float within the range of ±5%; when the flat-panel CT machine adopts 16K projection matrix value, the number of detector units in each row of the flat-panel detector is 3269, and the number can float within the range of ±5%.

6. The flat panel CT machine according to claim 1, characterized in that: The ray emitter adopts a 360° scanning mode and the rays emitted by the ray emitter are X-rays with a frequency higher than the detector reading frequency. When the ray emitter continuously emits rays during the acquisition and reading process of the flat-panel detector, when the flat-panel CT machine adopts a 4K projection matrix value, the number of detector units in each row of the flat-panel detector is 1156, and the number can fluctuate within the range of ±5%; when the flat-panel CT machine adopts an 8K projection matrix value, the number of detector units in each row of the flat-panel detector is 1634, and the number can fluctuate within the range of ±5%; when the flat-panel CT machine adopts a 16K projection matrix value, the number of detector units in each row of the flat-panel detector is 2312, and the number can fluctuate within the range of ±5%.

7. The flat panel CT machine according to claim 1, characterized in that: The flat panel CT machine also includes a cooling device, which is arranged at the bottom of the flat panel detector and can rotate synchronously with the flat panel detector; when the flat panel CT machine adopts a 360° scanning scanning method, the cooling device adopts a semiconductor refrigeration method.

8. The flat panel CT machine according to claim 1, characterized in that: The scanning frame of the flat-panel CT machine is provided with a plurality of positioning lights, and the positioning lights project at least two laser positioning lines falling in the shoulder width direction, which are used for front and rear positioning of the scanning part so that the scanning part is positioned within the maximum detection range of the flat-panel detector.

Images