Method and apparatus for increasing real-time detector dynamic range in triggered mode

Abstract

The application relates to a method and device for improving the dynamic range of a detector in real time in a trigger mode, which method comprises the following steps: generating an initial pulse signal synchronized with a first external trigger signal, and using the initial pulse signal to control a flat panel detector to read out an image data stream; generating an image frame from the image data stream read out by the flat panel detector under the control of the initial pulse signal; generating a plurality of preset pulse signals within the interval time of two adjacent external trigger signals, and using each pulse in the plurality of preset pulse signals to control the flat panel detector to read out an image data stream; and generating an image frame by performing arithmetic average processing on the plurality of image data streams read out by the flat panel detector under the control of the plurality of preset pulse signals. The application has the real-time performance of the prior art, and can improve the dynamic range without additional operation of a user, thereby greatly reducing the burden of the user.

Description

Technical Field

[0001] This invention relates to the technical field of improving the dynamic range of detectors, and more specifically to a method and apparatus for improving the dynamic range of detectors in real time under trigger mode. Background Technology

[0002] A flat panel detector is a radiation detection device specifically designed for X-ray imaging, widely used in fields such as dental CT, C-arm imaging, and industrial non-destructive testing. In flat panel detector applications, the density variation of the object being imaged typically ranges significantly, thus placing high demands on the detector's dynamic range. For users, a higher dynamic range means clearer detail and lower radiation dose. Currently, there are two main methods for improving the dynamic range of flat panel detectors:

[0003] Method one uses flat panel detectors with different gains. First, a grayscale image is acquired at each gain. Then, the grayscale value of each pixel in the different images is determined and selected. Finally, the selected grayscale values ​​of each pixel are merged to form the final grayscale image. In the final grayscale image, pixels with weaker light intensity are typically output with the image at a higher gain, while pixels with stronger light intensity are output with the image at a lower gain. Since higher gain corresponds to a better signal-to-noise ratio, and lower gain corresponds to a higher saturation dose, the dynamic range of the final merged image is significantly improved. However, this method requires designing multiple gain levels for the flat panel detector, which significantly reduces the yield of its core photoelectric conversion chip. Furthermore, variations in chip manufacturing can lead to differences in the gain of each pixel, necessitating a complex gain correction method to adjust the gain of each pixel.

[0004] Method two is based on the idea of ​​replacing a single long integration time acquisition with multiple short integration time acquisitions. Flat panel detector systems typically use gigabit networks to transmit data. Due to the bandwidth limitations of gigabit networks, the frame rate used by the user is usually lower than the maximum frame rate that the flat panel detector can actually operate at. When the flat panel detector actually operates at N times the frame rate set by the user, since the integration time is reduced to 1 / N of the original, the saturation dose rate will increase by N times, and the corresponding dynamic range will also increase by √N times, where N is an integer greater than 1. It can be seen that the advantage of this method is that it does not require designing multiple gain levels and complex gain correction methods. The improvement in dynamic range can be achieved by adjusting the actual operating frame rate inside the flat panel detector and performing a certain program of multi-frame superposition.

[0005] The flat panel detector has two acquisition modes: free mode and triggered mode. In free mode, the user first sets the frame rate, and then, after the user sets the start acquisition command, the flat panel detector continuously reads signals at the preset frame rate. In triggered mode, after the user sets the start acquisition command, the user uses an external signal to control the flat panel detector to read signals. According to the difference in trigger timing, the trigger mode is further divided into rising edge trigger, falling edge trigger, high level trigger, low level trigger, etc.

[0006] Taking falling edge triggering as an example, after the user sets the start acquisition command, the user inputs a trigger signal from outside the flat panel detector. When the flat panel detector receives the falling edge of the trigger signal, it immediately begins signal readout. Due to the line-by-line scanning readout method of the flat panel detector, there is a certain readout time interval Tr. This time is directly related to the design of the core photoelectric conversion chip of the flat panel detector and is usually a fixed value in the same mode. The interval between two adjacent falling edges of external trigger signals is called the integration time. The integration time is controlled by the user and can be changed as needed. During continuous X-ray source exposure, the integration time is positively correlated with the received dose of the flat panel detector.

[0007] As can be seen, the implementation of Method 2 depends on the frame rate set by the user. When the user uses the trigger mode, the frame rate is determined by the trigger signal interval input by the user. Therefore, if the trigger signal interval input by the user is inappropriate, Method 2 will not be able to be implemented effectively.

[0008] Method 3 is the method mentioned in the patent application "A method and apparatus for improving the dynamic range of a flat panel detector in trigger mode" provided by the patent applicant of this invention. In this method, the addition of the detection module brings some additional problems: First, the user must input a second trigger signal before the image data will be output, which affects its application in single-frame trigger scenarios; Second, compared with the traditional method, there will be an additional frame time delay in the output of its image data. Summary of the Invention

[0009] To address the shortcomings of existing technologies, such as the significant decrease in yield of the core photoelectric conversion chip due to the need for multiple gain levels in the detector, variations in chip manufacturing leading to differences in gain for each pixel necessitate complex gain correction methods, which place high demands on user hardware performance, and the ineffectiveness of improving the detector's dynamic range in trigger mode due to user-set frame rate (the interval between user-input trigger signals determines the frame rate), and the additional problems arising from the addition of the detection module (firstly, image data output only occurs after the user inputs a second trigger signal, affecting its application in single-frame trigger scenarios; secondly, compared to traditional methods, the image data output suffers from an additional frame time delay), this invention provides a method and apparatus for real-time improvement of the detector's dynamic range in trigger mode.

[0010] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0011] The method for improving the dynamic range of a detector in real time under trigger mode includes the following steps:

[0012] An initial pulse signal synchronized with the first external trigger signal is generated, and the initial pulse signal is used to control the flat panel detector to perform one image data stream readout;

[0013] The image data stream read by the flat panel detector under the control of the initial pulse signal is used to generate a frame image.

[0014] Multiple preset pulse signals are generated within the interval between two adjacent external trigger signals, and each pulse of the multiple preset pulse signals is used to control the flat panel detector to perform an image data stream readout once; wherein, among the multiple preset pulse signals, the last preset pulse signal is synchronized with the latter of the two adjacent external trigger signals;

[0015] The multiple image data streams read by the flat panel detector under the control of multiple preset pulse signals are arithmetically averaged to generate a single image frame.

[0016] The beneficial effects of this invention are as follows: First, an initial pulse signal synchronized with the first external trigger signal is generated, and the initial pulse signal is used to control the flat panel detector to perform one image data stream readout. Therefore, the output image of the flat panel detector is generated and controlled simultaneously with the issuance of the first external trigger signal. Multiple preset pulse signals are generated within the interval between two adjacent external trigger signals, and each pulse of the multiple preset pulse signals is used to control the flat panel detector to perform one image data stream readout. The multiple image data streams read out by the flat panel detector under the control of the multiple preset pulse signals are arithmetically averaged to generate one frame image. This not only achieves the real-time readout of the corresponding signal and image output under the triggering of the external trigger signal, as is the traditional method, but also improves the dynamic range. Therefore, this invention has the same real-time performance as the traditional method, while achieving improved dynamic range without additional user operation, greatly reducing the user's burden.

[0017] Based on the above technical solution, the present invention can be further improved as follows.

[0018] Furthermore, the initial pulse signal and the preset pulse signal are triggered in the same way; the triggering mode of the initial pulse signal or the preset pulse signal is rising edge triggering, falling edge triggering, high level triggering, or low level triggering.

[0019] Furthermore, the external trigger signal is a pulse signal, and the external trigger signal is triggered in the same way as the initial pulse signal or the preset pulse signal.

[0020] Furthermore, among the plurality of preset pulse signals, the interval between the first preset pulse signal and the preceding of the two adjacent trigger signals is greater than or equal to the time for the flat panel detector to read out an image data stream once.

[0021] Furthermore, the feature is that the interval between two adjacent preset pulse signals is greater than or equal to the time it takes for the flat panel detector to read out one image data stream.

[0022] To address the aforementioned technical problems, the present invention also provides a device for real-time improvement of the dynamic range of a detector in trigger mode, the specific technical solution of which is as follows:

[0023] A device for improving the dynamic range of a detector in real time under trigger mode, including a trigger signal conversion module;

[0024] The trigger signal conversion module is used to generate an initial pulse signal synchronized with the first external trigger signal, and to use the initial pulse signal to control the flat panel detector to perform one image data stream readout; wherein, the flat panel detector generates one frame image from the image data stream readout by the flat panel detector under the control of the initial pulse signal.

[0025] The trigger signal conversion module is further configured to generate multiple preset pulse signals within the interval between two adjacent external trigger signals, and use each of the multiple preset pulse signals to control the flat panel detector to read out an image data stream once; wherein, among the multiple preset pulse signals, the last preset pulse signal is synchronized with the latter of the two adjacent external trigger signals; the flat panel detector performs an arithmetic average of the multiple image data streams read out by the flat panel detector under the control of the multiple preset pulse signals to generate a frame image.

[0026] Furthermore, the initial pulse signal and the preset pulse signal are triggered in the same way; the triggering mode of the initial pulse signal or the preset pulse signal is rising edge triggering, falling edge triggering, high level triggering, or low level triggering.

[0027] Furthermore, the external trigger signal is a pulse signal, and the external trigger signal is triggered in the same way as the initial pulse signal or the preset pulse signal.

[0028] Furthermore, among the plurality of preset pulse signals, the interval between the first preset pulse signal and the preceding of the two adjacent trigger signals is greater than or equal to the time for the flat panel detector to read out an image data stream once.

[0029] Furthermore, the interval between two adjacent preset pulse signals is greater than or equal to the time it takes for the flat panel detector to read out one image data stream. Attached Figure Description

[0030] Figure 1 This is a flowchart of a method for improving the dynamic range of a detector in real time under a trigger mode, according to an embodiment of the present invention.

[0031] Figure 2 This is a falling edge triggering timing diagram under the conventional method in this embodiment of the invention;

[0032] Figure 3 This is the falling edge triggering timing of a method for real-time improvement of detector dynamic range based on a triggering mode in an embodiment of the present invention. Figure 1 ;

[0033] Figure 4 This is the falling edge triggering timing of a method for real-time improvement of detector dynamic range based on a triggering mode in an embodiment of the present invention. Figure 2 . Detailed Implementation

[0034] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. The detector in this invention mainly refers to a flat panel detector.

[0035] Example 1

[0036] like Figure 1 As shown, this embodiment provides a method for improving the dynamic range of a detector in real time under trigger mode, including the following steps:

[0037] S1. Generate an initial pulse signal synchronized with the first external trigger signal, and use the initial pulse signal to control the flat panel detector to perform one image data stream readout;

[0038] S2. Generate a frame image from the image data stream read out by the flat panel detector under the control of the initial pulse signal;

[0039] S3. Generate multiple preset pulse signals within the interval between two adjacent external trigger signals, and use each of the multiple preset pulse signals to control the flat panel detector to perform one image data stream readout.

[0040] Among the plurality of preset pulse signals, the last preset pulse signal is synchronized with the latter of the two adjacent external trigger signals.

[0041] Specifically, among the plurality of preset pulse signals, the interval between the first preset pulse signal and the preceding of two adjacent trigger signals is greater than or equal to the time required for the flat panel detector to perform one image data stream readout. The interval between two adjacent preset pulse signals is greater than or equal to the time required for the flat panel detector to perform one image data stream readout. The interval between a preset pulse signal adjacent to the initial pulse signal and the initial pulse signal is greater than or equal to the time required for the flat panel detector to perform one image data stream readout.

[0042] S4. Perform an arithmetic average on the multiple image data streams read by the flat panel detector under the control of multiple preset pulse signals to generate a frame image.

[0043] Preferably, the initial pulse signal and the preset pulse signal are triggered in the same way; the triggering mode of the initial pulse signal or the preset pulse signal is rising edge triggering, falling edge triggering, high level triggering, or low level triggering. The external trigger signal is a pulse signal, and the external trigger signal is triggered in the same way as the initial pulse signal or the preset pulse signal.

[0044] Among them, falling edge triggering means that the time interval between the falling edges of two adjacent pulses is the integral time; rising edge triggering means that the time interval between the rising edges of two adjacent pulses is the integral time; high level triggering means that the duration of a high level pulse is the integral time; low level triggering means that the duration of a low level pulse is the integral time.

[0045] like Figure 2 As shown, after the user sets the start acquisition command, the user inputs a trigger signal from outside the detector. When the detector receives the falling edge of the trigger signal, it immediately begins signal readout. Due to the detector's line-by-line scanning readout method, there is a certain readout time interval Tr. This time is directly related to the design of the detector's core photoelectric conversion chip and is usually a fixed value in the same mode. The interval between two adjacent falling edges of the external trigger signal is called the integration time. The integration time is controlled by the user and can be changed as needed. During continuous X-ray source exposure, the integration time is positively correlated with the received dose of the detector.

[0046] As can be seen, the implementation of Method 2 depends on the frame rate set by the user. When the user uses the trigger mode, the frame rate is determined by the interval of the trigger signal input by the user. In this case, Method 2 will not be able to be implemented effectively.

[0047] like Figure 3 As shown, the specific steps of the method for improving the dynamic range of the detector in real time under the above-mentioned triggering mode are as follows:

[0048] ①: Set the command to start data collection;

[0049] ②: Set the nth trigger signal transition edge. Each trigger signal transition edge corresponds to a time, that is, the time corresponding to the 1st trigger signal transition edge is k1, and the time corresponding to the nth trigger signal transition edge is kn. At time k1, the trigger signal conversion module inside the detector synchronously outputs a transition edge to control the detector to read out an image data stream once, that is, the initial image data. The image corresponding to the 1st trigger signal is generated using this image data stream, that is, the final image data.

[0050] ③: The user presets the coefficient N and the time interval T1 to T(N-1). After time k1, the internal trigger signal conversion module outputs N-1 pulses at different time intervals T1 to T(N-1), and the detector performs N-1 signal readouts accordingly. The user preset coefficient N is a positive integer greater than or equal to 2.

[0051] ④: At time k2, the internal trigger signal conversion module synchronously outputs a transition edge to control the detector to read out the signal; the user-preset time interval T1 to T(N-1) is greater than or equal to the signal readout time interval Tr;

[0052] ⑤: The final image data is generated by arithmetically averaging the N image data streams from steps ③ to ④.

[0053] ⑥: Repeat steps ③ to ⑤ until the user sets a stop collection command.

[0054] The dynamic range is maximized when all preset time intervals T1 to T(N-1) are equal to the ratio of the integration time T to the preset coefficient N, resulting in a √N-fold increase in dynamic range. When this condition is not met, the increase in dynamic range is determined by the maximum value among T1 to TN. The interval between two adjacent external trigger signal edges is called the integration time. The integration time is controlled by the user and can be changed as needed. During continuous radiation source exposure, the integration time is positively correlated with the received dose from the detector.

[0055] like Figure 4 As shown, the trigger mode uses the falling edge mode, the user presets the coefficient N to 2, the detector's readout time for one frame is 10ms, the user presets T1 = 10ms, the gigabit network's maximum transmission speed is 40fps, and the user sets the trigger signal interval to 25ms. Under these conditions, the specific steps are as follows:

[0056] S10, Set the start acquisition command;

[0057] S11. Set the transition time of the nth trigger signal to kn. At time k1, the internal trigger signal conversion module synchronously outputs a transition edge to control the detector to read out the signal. Use this image data stream to generate the image corresponding to the first trigger signal, which is the final image data.

[0058] S12. After time k1, the internal trigger signal conversion module outputs a pulse every 10ms, corresponding to the detector performing one signal readout.

[0059] S13. At time k2, the internal trigger signal conversion module synchronously outputs a transition edge to control the detector to read out the signal.

[0060] S14. The image corresponding to the second trigger signal is generated by arithmetic averaging the image data streams from steps S12 to S13, which is the final image data.

[0061] S15. Repeat steps S12 to S14 until the user sets a stop acquisition command.

[0062] contrast Figure 2As shown in the traditional method, the number of trigger signals input by the user matches the number of output image data streams, and the image output times are also completely consistent, eliminating the delay of one frame. Furthermore, the integration times for the two signal readouts are 10ms and 15ms respectively, corresponding to the traditional method's single 25ms integration time. This results in no loss of charge generated during exposure, fully meeting user requirements. Finally, by splitting the integration time from 25ms to 10ms and 15ms, the saturation dose rate can be increased by 1.67 times, corresponding to a 1.18 times improvement in dynamic range.

[0063] This invention, through a trigger signal conversion module inside the detector, pre-generates multiple trigger signals for signal readout. After the external trigger signal transition edge actually arrives, the last trigger signal is synchronously output internally. Finally, the image output corresponding to the current trigger signal is generated by arithmetically averaging the image stream outputs corresponding to all trigger signals. This achieves the same signal readout and image output as traditional methods, which require external trigger signal transition edges, while also improving the dynamic range. Therefore, this invention offers the same real-time performance as traditional methods, while simultaneously improving the dynamic range without requiring additional user intervention, significantly reducing the user's burden.

[0064] Example 2

[0065] Based on Embodiment 1, this embodiment provides a device for real-time improvement of the dynamic range of a detector in trigger mode. The device for real-time improvement of the dynamic range of a detector in trigger mode includes a trigger signal conversion module.

[0066] The trigger signal conversion module is used to generate an initial pulse signal synchronized with the first external trigger signal, and to use the initial pulse signal to control the flat panel detector to perform one image data stream readout; wherein, the flat panel detector generates one frame image from the image data stream readout by the flat panel detector under the control of the initial pulse signal.

[0067] The trigger signal conversion module is further configured to generate multiple preset pulse signals within the interval between two adjacent external trigger signals, and use each of the multiple preset pulse signals to control the flat panel detector to read out an image data stream once; wherein, among the multiple preset pulse signals, the last preset pulse signal is synchronized with the latter of the two adjacent external trigger signals; the flat panel detector performs an arithmetic average of the multiple image data streams read out by the flat panel detector under the control of the multiple preset pulse signals to generate a frame image.

[0068] The initial pulse signal and the preset pulse signal are triggered in the same way; the triggering mode of the initial pulse signal or the preset pulse signal is rising edge triggering, falling edge triggering, high level triggering, or low level triggering. The external trigger signal is a pulse signal, and the external trigger signal is triggered in the same way as the initial pulse signal or the preset pulse signal.

[0069] Among the plurality of preset pulse signals, the interval between the first preset pulse signal and the preceding trigger signal among two adjacent trigger signals is greater than or equal to the time taken for the flat panel detector to perform one image data stream readout. The interval between two adjacent preset pulse signals is greater than or equal to the time taken for the flat panel detector to perform one image data stream readout.

[0070] This embodiment first generates an initial pulse signal synchronized with the first external trigger signal, and uses this initial pulse signal to control the flat panel detector to perform one image data stream readout. Therefore, the image output by the flat panel detector is generated and controlled simultaneously with the first external trigger signal. Multiple preset pulse signals are generated within the interval between two adjacent external trigger signals, and each of these preset pulse signals is used to control the flat panel detector to perform one image data stream readout. The multiple image data streams read out by the flat panel detector under the control of the multiple preset pulse signals are arithmetically averaged to generate one frame image. This achieves both the real-time readout of the corresponding signal and image output under the triggering of the external trigger signal, as in traditional methods, and improves the dynamic range. Therefore, this invention has the same real-time performance as traditional methods, while achieving improved dynamic range without additional user operation, greatly reducing the user's burden.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving the dynamic range of a detector in real time under trigger mode, characterized in that, Includes the following steps: An initial pulse signal synchronized with the first external trigger signal is generated, and the initial pulse signal is used to control the flat panel detector to perform one image data stream readout; The image data stream read by the flat panel detector under the control of the initial pulse signal is used to generate a frame image. Multiple preset pulse signals are generated within the interval between two adjacent external trigger signals, and each pulse of the multiple preset pulse signals is used to control the flat panel detector to perform an image data stream readout once; wherein, among the multiple preset pulse signals, the last preset pulse signal is synchronized with the latter of the two adjacent external trigger signals; The multiple image data streams read by the flat panel detector under the control of multiple preset pulse signals are arithmetically averaged to generate a single image frame. Among the plurality of preset pulse signals, the interval between the first preset pulse signal and the preceding of the two adjacent trigger signals is greater than or equal to the time for the flat panel detector to read out one image data stream; The interval between two adjacent preset pulse signals is greater than or equal to the time it takes for the flat panel detector to read out one image data stream.

2. The method for real-time improvement of the detector's dynamic range under the triggering mode according to claim 1, characterized in that, The initial pulse signal and the preset pulse signal are triggered in the same way; the triggering mode of the initial pulse signal or the preset pulse signal is rising edge triggering, falling edge triggering, high level triggering, or low level triggering.

3. The method for improving the dynamic range of a detector in real time under the triggering mode according to claim 2, characterized in that, The external trigger signal is a pulse signal, and the external trigger signal is triggered in the same way as the initial pulse signal or the preset pulse signal.

4. A device for real-time improvement of the dynamic range of a detector in trigger mode, characterized in that, Includes a trigger signal conversion module; The trigger signal conversion module is used to generate an initial pulse signal synchronized with the first external trigger signal, and to use the initial pulse signal to control the flat panel detector to perform one image data stream readout; wherein, the flat panel detector generates one frame image from the image data stream readout by the flat panel detector under the control of the initial pulse signal. The trigger signal conversion module is further configured to generate multiple preset pulse signals within the interval between two adjacent external trigger signals, and use each of the multiple preset pulse signals to control the flat panel detector to read out an image data stream once; wherein, among the multiple preset pulse signals, the last preset pulse signal is synchronized with the latter of the two adjacent external trigger signals; the flat panel detector performs an arithmetic average of the multiple image data streams read out by the flat panel detector under the control of the multiple preset pulse signals to generate a frame image; Among the plurality of preset pulse signals, the interval between the first preset pulse signal and the preceding of the two adjacent trigger signals is greater than or equal to the time for the flat panel detector to read out one image data stream; The interval between two adjacent preset pulse signals is greater than or equal to the time it takes for the flat panel detector to read out one image data stream.

5. The device for real-time improvement of the detector's dynamic range in trigger mode according to claim 4, characterized in that, The initial pulse signal and the preset pulse signal are triggered in the same way; the triggering mode of the initial pulse signal or the preset pulse signal is rising edge triggering, falling edge triggering, high level triggering, or low level triggering.

6. The apparatus for real-time improvement of the detector's dynamic range in trigger mode according to claim 5, characterized in that, The external trigger signal is a pulse signal, and the external trigger signal is triggered in the same way as the initial pulse signal or the preset pulse signal.

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