Photon counting detector correction method and apparatus

Abstract

The application discloses a photon counting detector correction method and device. The method comprises the following steps: determining the count rate of each energy interval of photon counting data according to the photon counting data output by a photon counting detector; determining the corresponding theoretical count rate according to the pulse pile-up model of the photon counting detector and the count rate sum of each energy interval; the pulse pile-up model represents a first corresponding relationship between the actual count rate and the theoretical count rate; determining the first pile-up compensation amount of each energy interval according to the count rate of each energy interval and the theoretical count rate; and correcting the count rate of the corresponding energy interval by using the first pile-up compensation amount of each energy interval. The application calculates the pile-up compensation amount based on the pulse pile-up model representing the first corresponding relationship between the actual count rate and the theoretical count rate, and corrects the count rate, so that the actual operation is simple, the calculation amount is small, the correction is more accurate, and the correction effect can meet the clinical use requirements.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a photon counting detector calibration method and apparatus. Background Technology

[0002] Photon counting detectors (PCDs) in medical devices offer numerous advantages in energy-spectral CT. PCDs measure the energy of received photons and classify them into different energy ranges. This spectral resolution capability enables photon counting spectral CT to acquire information about the composition of matter. Furthermore, the low electronic noise and smaller detector unit size of PCDs result in higher resolution and signal-to-noise ratio. However, due to the inherent characteristics of PCDs, their most significant drawback is the so-called pulse buildup effect. When the detector unit receives photons, if the time interval between their arrivals is less than a threshold (dead time), pulse buildup occurs, preventing the detector unit from accurately counting the incident photons. Since multiple photons correspond to only one pulse, this leads to lost counts by the PCD. The short time intervals and altered pulse height also cause spectral distortion, ultimately resulting in inaccurate image values ​​and reduced image quality in the energy-spectral imaging. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the above-mentioned defects in the prior art and provide a photon counting detector calibration method and device.

[0004] The present invention solves the above-mentioned technical problems through the following technical solution:

[0005] Firstly, a photon counting detector calibration method is provided, comprising:

[0006] Based on the photon counting data output by the photon counting detector, determine the counting rate for each energy range of the photon counting data;

[0007] Based on the pulse stacking model of the photon counting detector and the sum of the count rates of each energy range, the corresponding theoretical count rate is determined; the pulse stacking model represents the first correspondence between the actual count rate and the theoretical count rate.

[0008] Based on the count rate of each energy range and the theoretical count rate, determine the first stacking compensation amount for each energy range;

[0009] The count rate of the corresponding energy range is corrected by using the first stacking compensation amount of each energy range.

[0010] Optionally, it also includes:

[0011] The second stacking compensation amount for each energy range is determined based on the correction parameters;

[0012] The initial corrected count rate is corrected a second time based on the second stacking compensation amount; wherein the initial corrected count rate is the correction result of correcting the count rate using the first stacking compensation amount.

[0013] Optionally, it also includes:

[0014] By fitting the residual terms for each energy range, a polynomial is obtained that characterizes the second correspondence between the residual terms and the sum of the count rates; wherein the residual term is the difference between the theoretical count rate and the initial corrected count rate;

[0015] The coefficients of the polynomial are determined as the correction parameters.

[0016] Optionally, the pulse stacking model is constructed through the following steps:

[0017] When the X-ray tube outputs different X-ray tube intensities, samples of the total count rate of the photon counting detector are obtained respectively;

[0018] By fitting the X-ray tube strength and the total count rate sample, a first correspondence between the X-ray tube strength and the total count rate is obtained;

[0019] The pulse stacking model is constructed based on the first correspondence.

[0020] Optionally, based on the count rate of each energy range and the theoretical count rate, a first stacking compensation amount for each energy range is determined, including:

[0021] The energy transition coefficients for each energy range are determined based on the probability of the photon incident event and the theoretical count rate.

[0022] The first accumulation compensation amount for each energy range is determined based on the energy transition coefficient and the count rate of each energy range.

[0023] Secondly, a photon counting detector calibration device is provided, comprising:

[0024] The count rate determination module is used to determine the count rate of each energy range of the photon count data based on the photon count data output by the photon count detector.

[0025] An incident rate determination module is used to determine the corresponding theoretical count rate based on the pulse stacking model of the photon counting detector and the sum of the count rates of each energy range; the pulse stacking model represents the first correspondence between the actual count rate and the theoretical count rate;

[0026] The compensation amount determination module is used to determine the first stacking compensation amount for each energy range based on the count rate of each energy range and the theoretical count rate.

[0027] The first correction module is used to correct the count rate of the corresponding energy range by using the first stacking compensation amount of each energy range.

[0028] Optionally, it also includes:

[0029] The second correction module is used to determine the second stacking compensation amount for each energy range based on the initial corrected count rate obtained by correcting the count rate using the first stacking compensation amount, and to perform a second correction on the initial corrected count rate based on the second stacking compensation amount.

[0030] Optionally, it also includes:

[0031] The fitting module is used to fit the residual terms of each energy range to obtain a polynomial that characterizes the second correspondence between the residual terms and the sum of the count rates; wherein the residual term is the difference between the theoretical count rate and the initial corrected count rate;

[0032] The correction parameter determination module is used to determine the coefficients of the polynomial as the correction parameters.

[0033] Optionally, it also includes:

[0034] The model building module is used to obtain the total count rate samples of the photon counting detector when the X-ray tube outputs different X-ray tube intensities, fit the X-ray tube intensity and the total count rate samples to obtain a first correspondence between the X-ray tube intensity and the total count rate, and build the pulse stacking model based on the first correspondence.

[0035] Optionally, the compensation amount determination module includes:

[0036] The coefficient determination unit is used to determine the energy transition coefficients of each energy range based on the probability of the photon incident event and the theoretical counting rate.

[0037] The compensation amount determination unit is used to determine the first stacking compensation amount for each energy range based on the energy transition coefficient and the count rate of each energy range.

[0038] Thirdly, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the photon counting detector calibration method described in any of the preceding claims.

[0039] Fourthly, a computer-readable storage medium is provided, on which a computer program is stored, wherein the computer program, when executed by a processor, implements the photon counting detector calibration method described in any of the preceding claims.

[0040] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0041] The positive and progressive effects of this invention are as follows: This invention calculates the stacking compensation amount based on the pulse stacking model that characterizes the correspondence between the actual count rate and the theoretical count rate, and corrects the count rate. This method is simple to operate in practice, does not require phantoms made of various materials, and has a small amount of calculation and is more accurate. The correction effect can meet the needs of clinical use. Attached Figure Description

[0042] Figure 1 A flowchart of a photon counting detector calibration method provided as an exemplary embodiment of the present invention;

[0043] Figure 2 A flowchart of another photon counting detector calibration method provided as an exemplary embodiment of the present invention;

[0044] Figure 3 A comparison chart of experimental results provided for an exemplary embodiment of the present invention.

[0045] Figure 4a An effect diagram of pulse accumulation correction on a water model provided as an exemplary embodiment of the present invention;

[0046] Figure 4b An illustration of the effect of another pulse accumulation correction on a water model, provided as an exemplary embodiment of the present invention;

[0047] Figure 5 A schematic diagram of a photon counting detector calibration device provided as an exemplary embodiment of the present invention;

[0048] Figure 6 This is a schematic diagram of the structure of an electronic device provided as an exemplary embodiment of the present invention. Detailed Implementation

[0049] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0050] Currently, there are two main approaches to calibrating photon counting detectors in medical devices (e.g., CT scanners, PET scanners). One approach analyzes and models the pulse accumulation effect. Given the X-ray incident energy spectrum, detector response, and pulse shape, the output spectrum at which pulse accumulation occurs is calculated. This model is then added to the forward projection model to obtain a relatively accurate matrix material decomposition. The drawback of this method is that the prior information required for calibration is difficult to obtain in practical clinical applications. Furthermore, the computational cost of the analytical model is substantial, making real-time solution difficult and limiting its applicability. The other approach is based on fitting actual phantom data to establish a mapping relationship between actual measurements and theoretical calculations. This mapping relationship can be represented by a fitting model, and the fitting coefficients are saved for calibration. This method using actual phantoms has some practicality; however, its main problem is that the fitting error is difficult to guarantee. To obtain more widely applicable results, it is necessary to explore various combinations of different materials, which poses significant challenges in practical operation. In addition, there are some attempts using deep learning, although this method relies on large datasets. In summary, current calibration methods for photon counting detectors are very complex, computationally intensive, or not necessarily practically feasible, and may not achieve good calibration results.

[0051] To address the aforementioned issues, this invention provides a photon counting detector calibration method that is simple to operate, requires minimal computation, is more accurate, and achieves calibration results that meet clinical needs.

[0052] A photon counting detector can collect / acquire photon counts in different energy ranges. The counting rate differs for each energy range, and the counting rate for the i-th energy range is obtained as m. i (Actual count rate), assuming no pulse stacking effect, its theoretical count rate is n. i The purpose of photon counting detector calibration is to adjust m i Corrected to n i .

[0053] Figure 1 A flowchart of a photon counting detector calibration method provided as an exemplary embodiment of the present invention is included, comprising the following steps:

[0054] Step 101: Determine the count rate of each energy range of the photon count data based on the photon count data output by the photon count detector.

[0055] The photon counting detector can be a photon counting detector of a non-paralyzed model or a photon counting detector of a paralyzed model that has not reached the highest counting rate. This embodiment of the invention does not make any special limitation on this.

[0056] The photon count data output by the photon counting detector is the total count for each energy range within the integration time. The count rate for each energy range can be obtained by dividing the photon count data by the integration time. This count rate is the actual count rate. The division of energy ranges can be set according to actual conditions. For example, the energy range can be divided into 5 partitions: [20keV, 45keV], (45keV, 60keV], (60keV, 70keV], (7keV, 90keV], and (9keV, 255keV).

[0057] Step 102: Determine the corresponding theoretical count rate based on the pulse stacking model of the photon counting detector and the sum of the count rates in each energy range.

[0058] The pulse accumulation model characterizes the first correspondence between the actual count rate and the theoretical count rate, that is, the degree of pulse accumulation at the actual count rate. Based on this pulse accumulation model, the first accumulation compensation amount γ for the i-th energy range can be determined. i .

[0059] The sum of the count rates across all energy ranges is the sum of the count rates across all energy ranges. The sum of the count rates for a given detector element (labeled by channel and slice) is:

[0060] m=∑ i m i (1)

[0061] Where m represents the sum of count rates; m i This represents the count rate of the i-th energy range.

[0062] The following describes one way to construct a pulse stacking model:

[0063] S1. When the X-ray tube outputs different X-ray tube intensities, obtain the total count rate samples of the photon counting detector.

[0064] There is a one-to-one mapping between the theoretical count rate and the incident rate of a photon counting detector. Since the incident rate is related to the intensity of the X-ray tube, a pulse stacking model can be constructed based on the sum of the count rates of the photon counting detector when scanning at different X-ray tube intensities.

[0065] X-ray tube intensity can be characterized by the tube voltage and tube current. In S1, different tube currents are applied to the X-ray tube at a certain tube voltage to control the medical equipment to scan and obtain the photon count data output by the photon count detector (this photon count data is acquired without a phantom). Based on this photon count data, the total count rate sample corresponding to each tube intensity is determined.

[0066] Similar to determining the sum of count rates for each energy range, the sum of count rates corresponding to each X-ray tube intensity is the sum of the count rate samples for all energy ranges under each X-ray tube intensity, while the count rate sample for each energy range is the photon count data sample divided by the integration time.

[0067] In one implementation, the acquired photon count data samples are represented in the following format: [channel, slice, bin, view]. The data in the `view` dimension of the photon count data samples acquired from each X-ray tube intensity are averaged, and the total count rate sample is calculated based on the averaging result. Because only the deterministic portion of the pulse stacking effect can be corrected, the influence of noise distribution, etc., is not considered.

[0068] It should be noted that the photon counting detector in S1 can be the same as the photon counting detector in step 101, or another reference detector can be selected. Since the linear relationship between the X-ray tube intensity and the X-ray tube current significantly affects the accuracy of the pulse stacking model, this embodiment selects a photon counting detector with better linearity as the reference detector to obtain the total count rate sample. Better linearity means that the X-ray tube intensity and the current are linearly proportional or almost linearly proportional.

[0069] During the photon counting data acquisition process, the medical equipment gantry can be rotated or not. By setting a sufficient wire feeding time, the range of current applied to the X-ray tube can cover various scenarios used in clinical scanning, such as from 10mA to 500mA, so that the fitted pulse accumulation model can be applied to various scenarios and has high universality.

[0070] S2. Fit the X-ray tube strength and the total count rate of the sample to obtain the first correspondence between the X-ray tube strength and the total count rate.

[0071] In one embodiment, taking the X-ray tube current as a characterization of the X-ray tube intensity as an example, the X-ray tube intensity and the total count rate sample are fitted using the following formula:

[0072] m(I mA )=kI mA / (1+τkI mA (2)

[0073] Where, m(I) mA ) represents the X-ray tube current I mA During scanning, the total count rate of the photon counting detector is sampled; k represents the fitting coefficient; τ represents the time to death.

[0074] m(I mA ) and I mA Given a known quantity, by fitting m(I) mA ) and ImA By obtaining τ and k, the first correspondence between the X-ray tube current (characterizing the X-ray tube intensity) and the sum of the count rates can be determined.

[0075] It should be noted that the above formula is only an example. In practical applications, other formulas can be used to fit the first correspondence between the X-ray tube intensity and the sum of the count rates.

[0076] S3. Construct a pulse stacking model based on the first correspondence.

[0077] The first correspondence obtained from the fitting was determined as the pulse stacking model.

[0078] After obtaining the pulse accumulation model, the corresponding theoretical count rate can be determined by substituting the sum of the count rates in step 102 into the pulse accumulation model.

[0079] Transforming formula (2), we get:

[0080] kI mA =m(I mA )+τkI mA ·m(I mA (3)

[0081] Theoretically, the count rate of a photon counting detector has a one-to-one correspondence with the theoretical count rate. The linear part in formula (3) can be used as a reasonable estimate of the theoretical count rate, that is, kI mA As a reasonable estimate of the theoretical count rate, it is denoted as n(I mA Establish a mapping relationship between m and n, and rewrite formula (3) as follows:

[0082] n = m + Δm(m); (4)

[0083] Where Δm(m) represents the first stacking compensation amount, and n represents the theoretical count rate.

[0084] Based on the above formula derivation, it is proven that the first stacking compensation amount can be determined based on the pulse stacking model to achieve the correction of the photon counting detector.

[0085] Step 103: Determine the first stacking compensation amount for each energy range based on the count rate and theoretical count rate of each energy range.

[0086] In one embodiment, step 103 includes:

[0087] Step 103-1: Determine the energy transition coefficients for each energy range based on the probability of the photon incident event and the theoretical count rate.

[0088] Step 103-2: Determine the first stacking compensation amount for each energy range based on the energy transition coefficient and the count rate of each energy range.

[0089] The derivation of the formula is explained below:

[0090] The probability that a detector count corresponds to a k+1 photon incident event is:

[0091]

[0092] The average number of events corresponding to one count is:

[0093]

[0094] Where k is a positive integer.

[0095] Taking the count rate of the first energy range as an example, the highest energy threshold of the first energy range is usually set relatively low. When the pulse height of an event signal falls within the first energy range and pulse accumulation occurs, the pulse signal will often not fall within the first energy range, but will jump to a higher energy range. Therefore, the count of the first energy range corresponds to the signal that has not experienced pulse accumulation.

[0096] In other words, the correspondence between the count rate of the first energy range and the theoretical count rate is expressed as follows:

[0097]

[0098] Where m1 represents the count rate of the first energy range, n1 represents the theoretical count rate of the first energy range, and n represents the sum of theoretical count rates.

[0099] Transforming formula (7), we get:

[0100] n1 = m1 + m1(2nt + 1.5(nτ)) 2 (8)

[0101] In formula (8), 2 and 1.5 represent energy transition coefficients.

[0102] Combining formula (4), we can obtain m1(2nt+1.5(nτ)). 2 The first accumulation compensation amount is determined as the first energy range.

[0103] γ1=m1(2nt+1.5(nτ) 2 For the i-th (i>1) energy range, we need to consider the transitions in lower energy ranges. Using the same approach, the first accumulation compensation amount for each energy range is expressed as follows:

[0104] γ i =γi (m1.,.,m i ,nτ); (9)

[0105] After obtaining formula (9), the energy transition coefficient and the count rate of each energy range are substituted into formula (9) to obtain the first accumulation compensation amount of each energy range.

[0106] Step 104: Correct the count rate of the corresponding energy range by using the first stacking compensation amount of each energy range.

[0107] The correction formula in step 104 is expressed as follows:

[0108] n′ i =m i +γ i (10)

[0109] Where, n′ i To adopt the first stacking compensation amount γ i For count rate m i The result of the correction.

[0110] In this embodiment of the invention, the stacking compensation amount is calculated based on the pulse stacking model characterizing the correspondence between the actual count rate and the theoretical count rate, and the count rate is corrected. This method is simple to operate, does not require phantoms made of various materials, and has a small computational load and is more accurate. The correction effect is comparable to that of I. mA It exhibits a good linear relationship, which meets the needs of clinical use.

[0111] Figure 2 A flowchart of another photon counting detector calibration method provided as an exemplary embodiment of the present invention, the photon counting detector calibration method comprising the following steps:

[0112] Step 201: Determine the count rate of each energy range of the photon count data based on the photon count data output by the photon count detector.

[0113] Step 202: Determine the corresponding theoretical count rate based on the pulse stacking model of the photon counting detector and the sum of the count rates in each energy range.

[0114] Among them, the pulse stacking model represents the first correspondence between the actual count rate and the theoretical count rate.

[0115] Step 203: Determine the first stacking compensation amount for each energy range based on the count rate and theoretical count rate of each energy range.

[0116] Step 204: Correct the count rate of the corresponding energy range by using the first stacking compensation amount of each energy range.

[0117] The specific implementation methods of steps 201 to 204 are similar to those of steps 101 to 104, and will not be repeated here.

[0118] Step 205: Determine the second stacking compensation amount for each energy range based on the correction parameters.

[0119] The following describes one method for determining the correction parameters:

[0120] S1. Fit the residual terms and theoretical count rates for each energy range respectively to obtain a polynomial that represents the second correspondence between the residual terms and the sum of the theoretical count rates.

[0121] The residual term is the difference between the theoretical count rate and the initial corrected count rate. It should be noted that the initial corrected count rate in step S1 can be the correction result of the first stacking compensation amount in step 204 correcting the count rate of the corresponding energy range, or it can be obtained in advance based on experimental data.

[0122] S2. Determine the coefficients of the polynomial as the correction parameters.

[0123] For example, n′ i Achieving good linearity at low count rates, i.e., n′ i with I mA It closely approximates a linear relationship and is applicable to different X-ray incident spectra; that is, the spectral information is discretely contained in the counts of the photon counting detector in different energy ranges. For n′ at low count rates... i Linear fitting was performed, and the fitting result was linearly extrapolated to the region with a very high count rate. This result was used as n. i (I mA ),

[0124] n i =k i I mA (11)

[0125] The residual term n i -n′ i By fitting a polynomial to n, or other quantities that are directly proportional to n (taking n as an example), we obtain:

[0126]

[0127] Among them, a i,j Characterize the correction parameters.

[0128] Therefore, the fitted n i -n′ i and n j The correction parameters for each energy range can then be obtained. These correction parameters are used to calculate the second stacking compensation amount when calibrating the photon counting detector.

[0129] Step 206: Perform a second correction on the initial correction count rate based on the second stacking compensation amount.

[0130] The initial corrected count rate is the result of correcting the count rate using the first stacking compensation amount.

[0131] The correction formula in step 204 is expressed as follows:

[0132] n i =m i +γ i +Δ i (13)

[0133] This step is necessary because the response behavior of a photon counting detector to photons is exceptionally complex, and the pulse stacking model cannot fully describe the pulse stacking behavior. Furthermore, factors such as threshold drift and polarization inherent in the photon counting detector itself can cause nonlinearities between the output and input. By fitting the residuals caused by these factors using a polynomial, a second stacking compensation amount Δ is obtained to correct the count rate. i Then, based on the second stacking compensation, the photon counting detector is calibrated a second time, so that n i with I mA The linear correlation has been further improved, making it more in line with clinical needs.

[0134] Figure 3 This invention provides a comparative chart of experimental results for an exemplary embodiment. The photon counting detector technology is divided into five energy ranges: [20keV, 45keV], (45keV, 60keV], (60keV, 70keV], (7keV, 90keV], and (9keV, 255keV). The left chart shows the actual count rate m for different energy ranges tested under different X-ray tube currents. i The count rate m can be clearly seen. i with I mA The linear relationship is poor; the intermediate graph uses... Figure 1 The result m obtained by the photon counting detector calibration method shown i +γ i with I mA The relationship can be seen from the diagram m i +γ i with I mA It exhibits better linear correlation, achieving the expected effect of pulse accumulation correction; the right figure shows the results achieved using... Figure 2 The result m obtained by the photon counting detector calibration method shown i +γ i +Δ i with ImA The relationship can be seen from the diagram m i +γ i +Δ i with I mA The linear correlation was further improved, achieving the expected effect of pulse accumulation correction.

[0135] Furthermore, photon count data output from a photon counting detector (death time 16 ns) was obtained by scanning with an energy range of [30 keV, 60 keV], a scanning protocol of 140 kVp, a rack rotation speed of 1 s, and X-ray tube currents of 100 mA, 200 mA, and 300 mA, respectively. This data was then corrected using the photon counting detector correction method provided in this embodiment of the invention. The water model image reconstructed based on the correction results is shown in [link to relevant documentation]. Figure 4a The left, center, and right images in the figure correspond to the water model images reconstructed by scanning with X-ray tube currents of 100mA, 200mA, and 300mA, respectively. Figure 4a It can be seen that the water model CT obtained under the three different X-ray tube current conditions are consistent, which achieves the expected effect of pulse stacking correction.

[0136] The photon count data output by the photon counting detector (death time 16 ns) was obtained by scanning with an energy range of [60 keV, 255 keV], a scanning protocol of 140 kVp, a rack rotation speed of 1 s, and X-ray tube currents of 100 mA, 200 mA, and 300 mA, respectively. The photon counting detector correction method provided in this embodiment of the invention was used to correct the data. The water model image reconstructed based on the correction results is shown in [link to relevant documentation]. Figure 4b The left, center, and right images in the figure correspond to the water model images reconstructed by scanning with X-ray tube currents of 100mA, 200mA, and 300mA, respectively. Figure 4b It can be seen that the water model CT obtained under the three different X-ray tube current conditions are consistent, achieving the expected effect of pulse stacking correction.

[0137] Corresponding to the aforementioned embodiments of the photon counting detector calibration method, the present invention also provides embodiments of the photon counting detector calibration device.

[0138] Figure 5 A schematic diagram of a photon counting detector calibration device provided as an exemplary embodiment of the present invention, the device comprising:

[0139] The count rate determination module 51 is used to determine the count rate of each energy range of the photon count data based on the photon count data output by the photon count detector.

[0140] The incident rate determination module 52 is used to determine the corresponding theoretical count rate based on the pulse stacking model of the photon counting detector and the sum of the count rates of each energy range; the pulse stacking model represents the first correspondence between the actual count rate and the theoretical count rate.

[0141] The compensation amount determination module 53 is used to determine the first stacking compensation amount for each energy range based on the count rate of each energy range and the theoretical count rate.

[0142] The first correction module 54 is used to correct the count rate of the corresponding energy range by using the first stacking compensation amount of each energy range.

[0143] Optionally, it also includes:

[0144] The second correction module is used to determine the second stacking compensation amount for each energy range based on the initial corrected count rate obtained by correcting the count rate using the first stacking compensation amount, and to perform a second correction on the initial corrected count rate based on the second stacking compensation amount.

[0145] Optionally, it also includes:

[0146] The fitting module is used to fit the residual terms and theoretical count rates for each energy range respectively, and obtain a polynomial characterizing the second correspondence between the residual terms and the theoretical count rate; wherein, the residual term is the difference between the theoretical count rate and the initial corrected count rate;

[0147] The correction parameter determination module is used to determine the coefficients of the polynomial as the correction parameters.

[0148] Optionally, it also includes:

[0149] The model building module is used to obtain the total count rate samples of the photon counting detector when the X-ray tube outputs different X-ray tube intensities, fit the X-ray tube intensity and the total count rate samples to obtain a first correspondence between the X-ray tube intensity and the total count rate, and build the pulse stacking model based on the first correspondence.

[0150] Optionally, the compensation amount determination module includes:

[0151] The coefficient determination unit is used to determine the energy transition coefficients of each energy range based on the probability of the photon incident event and the theoretical counting rate.

[0152] The compensation amount determination unit is used to determine the first stacking compensation amount for each energy range based on the energy transition coefficient and the count rate of each energy range.

[0153] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of the present invention according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0154] Figure 6 This is a schematic diagram of the structure of an electronic device according to an example embodiment of the present invention, showing a block diagram of an exemplary electronic device 60 suitable for implementing embodiments of the present invention. Figure 6 The electronic device 60 shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of the present invention.

[0155] like Figure 6 As shown, the electronic device 60 can be manifested as a general-purpose computing device, such as a server device. The components of the electronic device 60 may include, but are not limited to: at least one processor 61, at least one memory 62, and a bus 63 connecting different system components (including memory 62 and processor 61).

[0156] Bus 63 includes a data bus, an address bus, and a control bus.

[0157] The memory 62 may include volatile memory, such as random access memory (RAM) 621 and / or cache memory 622, and may further include read-only memory (ROM) 623.

[0158] The memory 62 may also include a program tool 625 (or utility) having a set (at least one) program module 624, including but not limited to: an operating system, one or more application programs, other program modules, and program data, each or some combination of these examples may include an implementation of a network environment.

[0159] The processor 61 performs various functional applications and data processing, such as the methods provided in any of the above embodiments, by running computer programs stored in the memory 62.

[0160] Electronic device 60 can also communicate with one or more external devices 64 (e.g., keyboard, pointing device, etc.). This communication can be performed via input / output (I / O) interface 65. Furthermore, the model-generated electronic device 60 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public network, such as the Internet) via network adapter 66. As shown, network adapter 66 communicates with other modules of the model-generated electronic device 60 via bus 63. It should be understood that, although not shown in the figure, other hardware and / or software modules can be used in conjunction with the model-generated electronic device 60, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID (disk array) systems, tape drives, and data backup storage systems.

[0161] It should be noted that although several units / modules or sub-units / modules of the electronic device have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of the present invention, the features and functions of two or more units / modules described above can be embodied in one unit / module. Conversely, the features and functions of one unit / module described above can be further divided and embodied by multiple units / modules.

[0162] This invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method provided in any of the above embodiments.

[0163] The readable storage medium may be more specifically adopted, including but not limited to: portable disk, hard disk, random access memory, read-only memory, erasable programmable read-only memory, optical storage device, magnetic storage device, or any suitable combination thereof.

[0164] In a possible implementation, the present invention can also be implemented as a program product comprising program code, wherein when the program product is run on a terminal device, the program code is used to cause the terminal device to execute the method implementing any of the above embodiments.

[0165] The program code for executing the present invention can be written in any combination of one or more programming languages. The program code can be executed entirely on the user device, partially on the user device, as a standalone software package, partially on the user device and partially on a remote device, or entirely on a remote device.

[0166] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for calibrating a photon counting detector, characterized in that, include: Based on the photon counting data output by the photon counting detector, determine the counting rate for each energy range of the photon counting data; Based on the pulse stacking model of the photon counting detector and the sum of the count rates of each energy range, the corresponding theoretical count rate is determined; The pulse stacking model represents the first correspondence between the actual count rate and the theoretical count rate; The energy transition coefficients for each energy range are determined based on the probability of the photon incident event and the theoretical count rate. The first accumulation compensation amount for each energy range is determined based on the energy transition coefficient and the count rate of each energy range. The count rate of the corresponding energy range is corrected by using the first stacking compensation amount of each energy range; The pulse accumulation model is constructed using the following steps: When the X-ray tube outputs different X-ray tube intensities, samples of the total count rate of the photon counting detector are obtained respectively; By fitting the X-ray tube strength and the total count rate sample, a first correspondence between the X-ray tube strength and the total count rate is obtained; The pulse stacking model is constructed based on the first correspondence.

2. The photon counting detector calibration method according to claim 1, characterized in that, Also includes: The second stacking compensation amount for each energy range is determined based on the correction parameters; The initial corrected count rate is corrected a second time based on the second stacking compensation amount; wherein the initial corrected count rate is the correction result of correcting the count rate using the first stacking compensation amount.

3. The photon counting detector calibration method according to claim 2, characterized in that, Also includes: By fitting the residual terms and theoretical count rates for each energy range, a polynomial characterizing the second correspondence between the residual terms and the theoretical count rate is obtained; wherein, the residual term is the difference between the theoretical count rate and the initial corrected count rate; The coefficients of the polynomial are determined as the correction parameters.

4. A photon counting detector calibration device, characterized in that, include: The count rate determination module is used to determine the count rate of each energy range of the photon count data based on the photon count data output by the photon count detector. The model building module is used to obtain the total count rate samples of the photon counting detector when the X-ray tube outputs different X-ray tube intensities, fit the X-ray tube intensity and the total count rate samples to obtain the first correspondence between the X-ray tube intensity and the total count rate, and build a pulse stacking model based on the first correspondence. The incident rate determination module is used to determine the corresponding theoretical count rate based on the pulse stacking model of the photon counting detector and the sum of the count rates of each energy range; The pulse stacking model represents the first correspondence between the actual count rate and the theoretical count rate; Compensation amount determination module; The compensation amount determination module includes: a coefficient determination unit, used to determine the energy transition coefficient of each energy range based on the probability of the photon incident event and the theoretical count rate; and a compensation amount determination unit, used to determine the first stacking compensation amount of each energy range based on the energy transition coefficient and the count rate of each energy range. The first correction module is used to correct the count rate of the corresponding energy range by using the first stacking compensation amount of each energy range.

5. The photon counting detector calibration device according to claim 4, characterized in that, Also includes: The second correction module is used to determine the second stacking compensation amount for each energy range based on the initial corrected count rate obtained by correcting the count rate using the first stacking compensation amount, and to perform a second correction on the initial corrected count rate based on the second stacking compensation amount.

6. The photon counting detector calibration device according to claim 5, characterized in that, Also includes: The fitting module is used to fit the residual terms of each energy range to obtain a polynomial that characterizes the second correspondence between the residual terms and the sum of the count rates; wherein the residual term is the difference between the theoretical count rate and the initial corrected count rate; The correction parameter determination module is used to determine the coefficients of the polynomial as the correction parameters.

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