Method for correcting nonlinearities associated with photon-counting detectors in imaging devices

Abstract

The present invention involves the provision and use of new and improved methods and apparatus for calibrating imaging devices and / or accounting for and correcting for nonlinearities encountered in the use of PCDs in X-ray scanning applications to result in improved image quality.

Description

[Technical Field]

[0001] Applicant NeuroLogica Corporation, a subsidiary of Samsung Electronics Co., Ltd. Inventor Duhgoon Lee Doil Kim Junyoung Park Ibrahim Bechwati Pending Prior Patent Applications This patent application claims the benefit of pending prior U.S. Provisional Patent Application No. 63 / 420,336, filed October 28, 2022, by NeuroLogica Corporation, a subsidiary of Samsung Electronics Co., Ltd., for "COUNT CORRECTION METHOD FOR PHOTON COUNTING DETECTORS."

[0002] The above-identified patent applications are incorporated herein by reference. The present invention relates generally to imaging devices and detectors, and more particularly to computed tomography (CT) scanners and detectors for use with CT scanners. [Background technology]

[0003] A typical imaging device (hereinafter sometimes referred to as a "scanner") comprises an energy source for emitting energy that interacts with the object being imaged, a set of detectors (hereinafter sometimes referred to as "receivers") for measuring the interaction between the radiated energy and the object being imaged, and a computational engine for extracting information from the measurement data regarding the interaction between the radiated energy and the object being imaged.

[0004] A computational engine creates an image of the object being imaged from the measurement data. A common medical imaging device, a computed tomography (CT) scanner, uses a polychromatic X-ray tube as an energy source to emit X-ray energy that interacts with the object being scanned. With a CT scanner, the image receptor is a set of X-ray detectors positioned diametrically opposite the X-ray source (i.e., the object being imaged is positioned between the X-ray source and the X-ray detector). The X-ray detectors are configured to convert the X-ray energy into an electrical current that can be measured. The measured electrical current is then used to create an image, and a computer assembles multiple segmented images into a 3D representation of the scanned object.

[0005] Energy integrating detectors (EIDs) are the most commonly used X-ray image receptors in medical X-ray imaging applications. In scanning applications utilizing EIDs, an X-ray source (e.g., an emitter configured to emit a polychromatic X-ray spectrum containing photons at different energy levels) is positioned facing the EID, and the object to be scanned is positioned between the X-ray source and the EID. As the X-ray source emits X-rays, the emitted photons of the polychromatic X-ray spectrum interact with the object to be scanned before contacting the EID. The EID averages the response from each X-ray photon weighted by its respective energy; that is, each X-ray photon is converted into a photon that can be measured using a simple photodiode. The number of photons depends on the energy of the incident X-ray photon. EIDs are sometimes called "indirect conversion detectors" because such detectors convert X-rays into light, which is then converted into electrical current (e.g., by a photodiode).

[0006] Photon counting detectors (PCDs) are re-emerging for use in X-ray image receptors in the field of nuclear medicine imaging. PCDs have been considered for use in medical imaging using computer-aided detection (CAD) since the late 1990s. PCDs capture each X-ray photon as it passes through the object being scanned after it is emitted from the X-ray source and register the energy level of that X-ray photon. The X-ray photon interacts with the PCD image receptor, producing an electrical pulse proportional to the X-ray photon's energy level. In binning mode, the pulses can then be binned together and counted based on their height (i.e., magnitude). PCDs are sometimes called "direct conversion detectors" because they directly convert X-ray photons into electrical current.

[0007] Conventional X-ray detectors generally operate as EIDs, converting X-ray photons into photons as a first step before converting them into a measurable electrical current. The number of photons depends on the energy of the X-ray photons. A photodiode is used to convert the photons into a current, the magnitude of which is a weighted sum of the X-ray photon energies.

[0008] However, the "linearity" of the detector is essential to producing an accurate representation of the object being imaged. Both EID and PCD suffer from a certain inherent degree of nonlinearity. EID detector nonlinearity is known in the art, and several solutions exist to help address it. However, PCD nonlinearity is an emerging area of ​​research that has not been addressed in the art.

[0009] Nonlinearities cause severe artifacts in images obtained with PCDs. Nonlinearities in PCD detectors can be attributed to two effects: (i) pulse pile-up, and (ii) charge sharing.

[0010] Pulse pileup typically occurs when pulses from two X-ray photons sum to create a single pulse with a magnitude higher than the pulses of the two separated X-ray photons. More specifically, pulse pileup occurs when two (or more) incident photons from an emitted X-ray beam strike a detector in close proximity, causing the individual pulses to merge together to create a single pulse with a magnitude higher than the actual magnitude of the two (or more) pulses separated. The new (combined) pulse appears to be generated by a single photon with a higher energy. If the magnitude of the resulting pulse is large enough, it will be rejected (e.g., by an appropriate software algorithm); otherwise, it will be registered as a single photon with a higher energy level than it should have been, thereby distorting the resulting image.

[0011] Charge sharing is generally the opposite of pulse pile-up: with charge sharing, the pulse from a single X-ray photon is split between two detectors, resulting in two pulses that have a lower magnitude than the actual pulse of the original single X-ray photon that was sought to be measured, thereby also causing distortions in the resulting image.

[0012] More specifically, due to charge sharing, the electron cloud associated with a single X-ray photon is detected by two adjacent detectors. The pulse charge becomes split into two pulses, each with a magnitude smaller than the actual magnitude of the pulse from a single X-ray photon. This results in the erroneous detection of two X-ray photons, each with a lower energy, and simultaneously losing the true (i.e., correct) information from the actual magnitude of the single X-ray photon. In binning mode (e.g., counting pulses based on their magnitude), the charge sharing effect is reduced by averaging data across multiple adjacent detectors. However, the charge sharing effect contributes to the nonlinearity of the PCD array and therefore results in image distortion.

[0013] Thus, there is a need for new and improved methods and apparatus for calibrating imaging devices and / or for accounting for and correcting for nonlinearities encountered in the use of PCDs in X-ray scanning applications to improve the resulting image quality. Summary of the Invention

[0014] The present invention involves the provision and use of new and improved methods and apparatus for calibrating imaging devices and / or accounting for and correcting for nonlinearities encountered in the use of PCDs in X-ray scanning applications to improve the resulting image quality.

[0015] In one preferred form of the invention, there is provided a method for correcting nonlinearities associated with a photon counting detector (PCD) of an imaging device, the method comprising: providing a first scanning device and a second scanning device, each of the first and second scanning devices comprising an X-ray source configured to emit an X-ray beam and a detector array aligned with the X-ray beam, wherein the detector array of the first scanning device comprises a plurality of energy integrating detectors (EIDs) and the detector array of the second scanning device comprises a plurality of photocounting detectors (PCDs); detecting an X-ray beam that has passed through the object, the X-ray beam being scanned by a plurality of energy integrating detectors (EIDs); detecting an X-ray beam that has passed through the object, the X-ray beam being scanned by a plurality of photocounting detectors (PCDs); recording the x-ray beam detected by a plurality of energy integrating detectors (EIDs) as a first data set; recording the X-ray beam detected by the plurality of photocounting detectors (PCDs) as a second data set; generating a mathematical model using the first data set and the second data set; creating a data-driven model to complement the mathematical model, the data-driven model addressing limitations of the mathematical model and extending the scope of correction; applying the mathematical model and the data-driven model to the second data set to derive a damping coefficient; applying the attenuation coefficient to the second data set; generating a scanned image of the object from the second data set; Includes:

[0016] In another preferred form of the present invention, there is provided a method of correcting nonlinearities associated with a photon counting detector (PCD) of an imaging device, the method comprising: providing a scanning device comprising an x-ray source configured to emit an x-ray beam and a first detector array aligned with the x-ray beam, the first detector array comprising a plurality of energy integrating detectors (EIDs); detecting an X-ray beam that has passed through the object, the X-ray beam being scanned by a plurality of energy integrating detectors (EIDs); recording the X-ray beam that has passed through the object as scanned and detected by a plurality of energy integrating detectors (EIDs) as a first data set; replacing the first detector array with a second detector array, the second detector array comprising a plurality of photocounting detectors (PCDs); detecting an X-ray beam that has passed through the object, the X-ray beam being scanned by a plurality of photocounting detectors (PCDs); recording the X-ray beam that has passed through the object as scanned and detected by a plurality of photocounting detectors (PCDs) as a second data set; generating a correction model by analyzing the first data set and the second data set, the correction model comprising a damping coefficient; applying the attenuation coefficient to the second data set; generating a scanned image of the object from the second data set; Includes:

[0017] In another preferred form of the present invention, there is provided a system for correcting nonlinearities associated with a photon counting detector (PCD) of an imaging device, the system comprising: at least one scanning device comprising an X-ray source configured to emit an X-ray beam; a first detector array configured to be aligned with the X-ray beam, the first detector array comprising a plurality of energy integrating detectors (EIDs) for detecting the X-ray beam emitted by the X-ray source; a second detector array configured to be aligned with the X-ray beam, the second detector array comprising a plurality of photocounting detectors (PCDs) for detecting the X-ray beam emitted by the X-ray source; a first data set representing an X-ray beam passing through the object and detected by a plurality of energy integrating detectors (EIDs); a second data set representing the X-ray beam passing through the object and detected by a plurality of photocounting detectors (PCDs); a computer configured to (i) generate a mathematical model from the first data set and the second data set to derive an attenuation coefficient, and (ii) apply the attenuation coefficient to the second data set, thereby generating a scanned image of the object from the second data set; Equipped with.

[0018] In another preferred form of the present invention, there is provided a method of calibrating an imaging device with a photon counting detector (PCD), the method comprising: providing (i) an X-ray source configured to emit an X-ray beam; (ii) a first detector array configured to be aligned with the X-ray beam, the first detector array comprising a plurality of energy integrating detectors (EIDs) for detecting the X-ray beam emitted by the X-ray source; and (iii) a second detector array configured to be aligned with the X-ray beam, the second detector array comprising a plurality of photocounting detectors (PCDs) for detecting the X-ray beam emitted by the X-ray source; detecting an X-ray beam that has passed through the object, the X-ray beam being scanned by a plurality of energy integrating detectors (EIDs); recording the X-ray beam that has passed through the object as scanned and detected by a plurality of energy integrating detectors (EIDs) as a first data set; detecting an X-ray beam that has passed through the object, the X-ray beam being scanned by a plurality of photocounting detectors (PCDs); recording the X-ray beam that has passed through the object as scanned and detected by a plurality of photocounting detectors (PCDs) as a second data set; generating a mathematical model from the first data set and the second data set to derive a damping coefficient; applying the attenuation coefficient to the second data set to calibrate the imaging device; Includes:

[0019] These and other objects and features of the present invention will become apparent from the following detailed description of preferred embodiments of the invention, which should be considered in conjunction with the accompanying drawings, in which like numerals refer to like parts and in which: [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic diagram showing the exterior of an exemplary CT imaging device. [Figure 2] 1 is a schematic diagram showing the exterior of an exemplary CT imaging device. [Figure 3]FIG. 3 is a schematic diagram illustrating various components within the torus of the exemplary CT imaging device shown in FIGS. 1 and 2. [Figure 4] FIG. 1 is a schematic diagram illustrating how a single CT imaging device can be used to image an example object and obtain data from two different types of detectors. [Figure 5A] 1 is a schematic diagram illustrating a novel method for calibrating a CT system using detector data obtained using two different types of detectors. [Figure 5B] FIG. 1 is a schematic diagram illustrating a novel method for correcting data using a mathematical model derived by the present invention. [Figure 6] FIG. 1 shows an example image produced using raw (i.e., uncorrected) PCD X-ray detector data. [Figure 7] FIG. 1 shows an example image produced using raw (i.e., uncorrected) PCD X-ray detector data. [Figure 8] FIG. 1 shows an example image produced using raw (i.e., uncorrected) PCD X-ray detector data. [Figure 9] FIG. 7 shows the image of FIG. 6 after it has been "reconstructed" using corrected PCD measurements derived by applying the novel method of the present invention. [Figure 10] FIG. 8 shows the image of FIG. 7 after it has been "reconstructed" using corrected PCD measurements derived by applying the novel method of the present invention. [Figure 11] FIG. 9 shows the image of FIG. 8 after it has been "reconstructed" using corrected PCD measurements derived by applying the novel method of the present invention. [Figure 12] FIG. 1 shows an example image obtained using EID X-ray detector data. [Figure 13] FIG. 1 shows an example image obtained using EID X-ray detector data. [Figure 14] FIG. 1 shows an example image obtained using EID X-ray detector data. DETAILED DESCRIPTION OF THE INVENTION

[0021] Computed tomography (CT) In many situations, it may be desirable to image the interior of an opaque object. For example, and without limitation, in the medical field, it may be desirable to image the interior of a patient's body so as to be able to view internal structures without physically penetrating the patient's skin.

[0022] Computed tomography (CT) has emerged as a major imaging diagnostic modality in the medical field. CT imaging devices generally operate by directing x-rays at the body from various positions, detecting the x-rays that pass through the body, and then processing the detected x-rays to build up a three-dimensional (3D) data set of the patient's anatomy. This 3D data set can then be processed to create a 3D computer model of the patient's anatomy. The 3D data set and 3D computer model can then be visualized to provide images (e.g., slice images, 3D computer images, etc.) of the patient's anatomy.

[0023] 1 and 2, an exemplary CT imager 5 is shown. The CT imager 5 generally comprises a torus 10 supported by a base 15. A central opening 20 is formed in the torus 10. The central opening 20 receives the patient's anatomy to be scanned.

[0024] 3 , torus 10 generally comprises a stationary gantry 22, a rotating disk 23, an X-ray tube assembly 25, and an X-ray detector assembly 30. X-ray detector assembly 30 comprises a plurality of X-ray detectors 35. More specifically, stationary gantry 22 is disposed concentrically with central opening 20. Rotating disk 23 is rotatably mounted to stationary gantry 22. X-ray tube assembly 25 and X-ray detector assembly 30 are mounted to rotating disk 23 in diametrical opposition such that X-ray beam 40 (generated by X-ray tube assembly 25 and detected by X-ray detectors 35 of X-ray detector assembly 30) is passed through the anatomy of a patient disposed within central opening 20. The X-ray tube assembly 25 and the X-ray detector assembly 30 are mounted on the rotating disk 23 so that they rotate concentrically with the central opening 20, causing the X-ray beam 40 to pass through the patient's anatomy along a range of radial positions such that the CT imager 5 creates "slice" images of the anatomy penetrated by the X-ray beam. Furthermore, by moving the patient and the CT imager 5 relative to each other during the scan, a series of slice images can be acquired and then appropriately processed to create a 3D data set of the scanned anatomy. This 3D data set can then be processed to create a 3D computer model of the scanned anatomy. It is common to configure the X-ray detector assembly 30 so that multiple slices of images (e.g., 8 slices, 16 slices, 32 slices, etc.) can be acquired with each revolution of the rotating disk 23, thereby speeding up scan data acquisition.

[0025] In practice, it is now common to perform a helical scan of a patient's anatomy to generate a 3D data set of the scanned anatomy, which can then be processed to create a 3D computer model of the scanned anatomy. The 3D data set and 3D computer model can then be visualized to provide images (e.g., slice images, 3D computer images, etc.) of the patient's anatomy.

[0026] Various electronic hardware and software for controlling the operation of the rotating disk 23, the X-ray tube assembly 25, and the X-ray detector assembly 30, and for processing the acquired scan data to generate desired slice images, 3D data sets, and 3D computer models, may be well known in the art and may be located within the torus 10 and / or base 15.

[0027] Images produced by the CT imager 5 may be viewed on a display screen 41 provided on the CT imager 5 or on a remote screen (not shown). The X-ray beam 40 is preferably a polychromatic X-ray beam. The interaction between the X-ray beam 40 and the object being scanned results in attenuation of the X-ray beam by the object being imaged. The X-ray detector 35 of the X-ray detector assembly is preferably an X-ray solid-state detector that measures the level of attenuation of the X-ray beam 40 after passing through the object being scanned. invention The present invention addresses the non-linear behavior of imaging devices that utilize photocounting detectors (PCDs) to improve image quality.

[0028] More specifically, the present invention is based on converting the highly nonlinear measurements of a PCD X-ray detector 45 into a more appropriate form of measurement with similar nonlinear behavior to that of an EID X-ray detector 50. This is achieved by providing an accurate estimate of pulse pile-up and then correcting for the nonlinear behavior of the PCD X-ray detector 45 using data from a well-established (e.g., standardized) EID X-ray detector 50.

[0029] In summary, the three main steps of the novel method of the present invention are as follows: 1. Scan the object while collecting data using a standardized EID X-ray detector 50 and a PCD X-ray detector 45. The data collected from the EID X-ray detector 50 can then be used to estimate the counts of the PCD X-ray detector 45 using a mathematical model developed to describe the pulse pileup of the PCD X-ray detector 45.

[0030] 2. A mathematical model is generated to represent the pulse pile-up in the PCD X-ray detector 45. The mathematical model is used to correct for the non-linear behavior of the detector. 3. Use data-driven estimation to complement mathematical models. Data is collected using an EID X-ray detector 50 The first step in the novel method of the present invention is to collect data using a non-PCD detector that exhibits well-known behavior. By way of example, but not limitation, an EID X-ray detector 50 may be used to collect the data.

[0031] However, it should be understood that the data used to correct for nonlinearities in the PCD X-ray detectors 45 should be acquired using the same CT imager 5 that will be using those PCD X-ray detectors 45. For example, a particular CT imager 5 (or two identical CT imagers 5 of the same make and model) is ideal.

[0032] 4, one way to achieve nonlinearity correction using the same particular CT imaging device 5 involves replacing the X-ray detector assembly 30 used with that particular CT imaging device 5 with a second X-ray detector assembly 30. That is, performing a first set of scans using X-ray detector assembly 30 a with a plurality of standardized EID X-ray detectors 50, and then performing a second set of scans using X-ray detector assembly 30 a with a plurality of PCD X-ray detectors 45.

[0033] However, looking now at FIG. 5A, a more convenient (and efficient) method is to use two CT imagers 5 and 5a. According to this method of the present invention, one CT imager 5 is provided with an X-ray detector assembly 30 including a plurality of conventional EID X-ray detectors 50, and the other CT imager 5a is provided with an X-ray detector assembly 30a including a plurality of PCD X-ray detectors 45. The two CT imagers 5, 5a should have the same geometric dimensions and use the same electronic and mechanical components. In short, the two CT imagers 5, 5a should be of the same make and model, with the only substantial difference between the devices being the type of X-ray detectors forming their respective detector assemblies 30, 30a.

[0034] It is necessary, but not sufficient, to have the CT imagers 5, 5a configured with identical hardware (except for their respective detector assemblies 30, 30a). Another requirement is that data be acquired using the same settings for both CT imagers 5, 5a. The data should be acquired with the same voltage applied to the x-ray tube assembly 25, the same current applied to the x-ray tube assembly 25, and the same acquisition time.

[0035] The EID X-ray detector 50 is selected for use as the standardized detector because it provides the most accurate representation of the scanned object. Generate a mathematical model of pulse pileup in PCD 5A , EID X-ray detector 50 provides an accurate representation of the scanned object. However, due to the nonlinearity issues discussed above, PCD X-ray detector 45 does not provide an accurate representation of the scanned object. Therefore, the present invention provides a novel method that involves generating a mathematical model that helps "map" PCD X-ray detector 45 into the space of EID X-ray detector 50. In other words, the mathematical model of the present invention (sometimes referred to herein as a binned pixel correction (BPC) model) is used to map PCD detector 45 into a more appropriate space.

[0036] PCD corr =f(PCD meas ,EID meas ,Scanner paramas ) PCD corr is the corrected PCD data.

[0037] PCD meas is the measured PCD data. EID meas is the measured EID data. Scanner paramas is a unique set of parameters.

[0038] The measured data consists of several large data sets, each millions of points long. The measured data from each set is analyzed and processed to produce meaningful representations that are then used to create mathematical models.

[0039] The recorded count rate (A rec ) is the incident count rate (A inc ) and τ is the dead time. Using the non-invalidating model:

[0040]

number

[0041] The reference value R is the incidence rate (A inc ) The recorded count rate is the product of the single acquisition count M times the number of acquisitions per second, N acq Is: A inc =N acq ×k×R A rec =N acq ×M k is the proportionality constant. The final mathematical model can be written as a function of R and M:

[0042]

number

[0043] τ c is the total dead time per second. Two constants, k and τ c To estimate , the use of least squares estimation is used. Data-Driven Functions The mathematical model generated above has its limitations. To improve the accuracy of the correction of the PCD data, data is extracted from the measured PCD data (e.g., data showing unreliable outliers), and the remaining data is used to generate a data-driven model. The data-driven model is also used to extend the scope of the correction. The data-driven model used for the extended correction is as follows: PCD corr =g(PCD meas1 ,PCD meas2 ,···,PCD measn ) correction Using the two functions described above (i.e., the mathematical model and the data-driven model), the attenuation measured by the PCD X-ray detector 45 is corrected to generate a more accurate set of data. The "corrected" data will have the same nonlinearity as that of the EID X-ray detector 45. After applying the "corrections" (i.e., the mathematical model and the data-driven model), a tool suitable for producing an accurate image (e.g., a computer assembling a 3D image from multiple scan images) is configured to utilize the PCD "corrected" measurements to generate the image. The PCD X-ray detector measurements (M rec ) is used to generate the corrected attenuation. rec ) can be used with:

[0044]

number

[0045] Looking now at FIG. 5B, it will be appreciated that once the correction factors (i.e., the mathematical / BPC model) have been determined using the novel method discussed above, the correction factors can be applied to any CT device 5 utilizing a PCD detector (e.g., PCD detector 45) by applying the mathematical / BPC model to the scan data to generate a scan image from the corrected scan data.

[0046] 6-8 show example images generated using raw (i.e., uncorrected) PCD X-ray detector data without compensation for the nonlinear (e.g., pulse pile-up) characteristics of the PCD X-ray detector.

[0047] The non-uniform appearance of the images in Figures 6-8 is a result of the PCD non-linearity discussed above, which is more visible in the head phantom image shown in Figure 8 than in the non-circular shape of the human skull.

[0048] Figures 9-11 show the images of Figures 6-8 after being "reconstructed" using the corrected PCD measurements derived by applying the novel method discussed above. The image uniformity of Figures 9-11 (i.e., compared to Figures 6-8) is significantly improved after compensating for the nonlinear effects of the PCD detector.

[0049] Figures 12-14 show images obtained using EID X-ray detector data, and it will be appreciated that the images in Figures 12-14 are generally very similar to the images in Figures 9-11 obtained using the corrected PCD measurements according to the present invention. Modifications of the Preferred Embodiment It should be understood that many additional changes in the details, materials, steps, and arrangements of parts described and illustrated herein to explain the principles of the invention may be made by those skilled in the art while still remaining within the principles and scope of the invention.

Claims

1. 1. A method for correcting nonlinearities associated with a photon-counting detector (PCD) of an imaging device, comprising: providing a first scanning device and a second scanning device, each of the first and second scanning devices comprising an X-ray source configured to emit an X-ray beam and a detector array aligned with the X-ray beam, the detector array of the first scanning device comprising a plurality of energy integrating detectors (EIDs) and the detector array of the second scanning device comprising a plurality of photocounting detectors (PCDs); detecting an X-ray beam that has passed through an object scanned by the plurality of energy integrating detectors (EIDs); detecting an X-ray beam that has passed through the object and is scanned by the plurality of photocounting detectors (PCDs); recording the x-ray beam detected by the plurality of energy integrating detectors (EIDs) as a first data set; recording the X-ray beam detected by the plurality of photocounting detectors (PCDs) as a second data set; generating a mathematical model using the first data set and the second data set; creating a data-driven model to supplement the mathematical model, the data-driven model addressing limitations of the mathematical model and extending the scope of the correction; applying the mathematical model and the data-driven model to the second data set to derive a damping coefficient; applying the attenuation coefficient to the second data set; generating a scan of the object from the second data set; A method comprising:

2. The method of claim 1 , wherein the attenuation factor applied to the second data set corrects for the pulse pile-up effect.

3. The method of claim 1 , wherein the attenuation factor applied to the second data set corrects for the charge sharing effect.

4. The method of claim 1 , wherein the first scanning device and the second scanning device comprise computed tomography (CT) imaging devices.

5. The method of claim 4 , wherein the x-ray sources of the first scanning device and the second scanning device comprise x-ray tubes.

6. The method of claim 5 , wherein the x-ray beam emitted by the x-ray tube is a polychromatic x-ray beam.

7. The method of claim 1 , wherein the data-driven model is created by extracting data from the second data set prior to deriving the damping coefficients.

8. The method of claim 4 , wherein the computed tomography (CT) imaging devices comprise identically configured computed tomography (CT) imaging devices.

9. 1. A method for correcting nonlinearities associated with a photon-counting detector (PCD) of an imaging device, comprising: providing a scanning device comprising an x-ray source configured to emit an x-ray beam and a first detector array aligned with the x-ray beam, the first detector array comprising a plurality of energy integrating detectors (EIDs); detecting an X-ray beam that has passed through an object scanned by the plurality of energy integrating detectors (EIDs); recording the X-ray beam that has passed through the object as scanned and detected by the plurality of energy integrating detectors (EIDs) as a first data set; replacing the first detector array with a second detector array, the second detector array comprising a plurality of photocounting detectors (PCDs); detecting an X-ray beam that has passed through the object, the X-ray beam being scanned by a plurality of photocounting detectors (PCDs); recording the X-ray beam that has passed through the object as scanned and detected by the plurality of photocounting detectors (PCDs) as a second data set; generating a correction model by analyzing the first data set and the second data set, the correction model comprising a damping coefficient; applying the attenuation coefficient to the second data set; generating a scan of the object from the second data set; A method comprising:

10. 1. A system for correcting nonlinearities associated with a photon-counting detector (PCD) of an imaging device, comprising: at least one scanning device comprising an X-ray source configured to emit an X-ray beam; a first detector array configured to be aligned with the x-ray beam, the first detector array comprising a plurality of energy integrating detectors (EIDs) for detecting the x-ray beam emitted by the x-ray source; a second detector array configured to be aligned with the X-ray beam, the second detector array comprising a plurality of photocounting detectors (PCDs) for detecting the X-ray beam emitted by the X-ray source; a first data set representing an x-ray beam passing through an object and detected by the plurality of energy integrating detectors (EIDs); a second data set representing the X-ray beam passing through the object and detected by the plurality of photocounting detectors (PCDs); a computer configured to (i) generate a mathematical model from the first data set and the second data set to derive an attenuation coefficient, and (ii) apply the attenuation coefficient to the second data set, thereby generating a scanned image of the object from the second data set; A system comprising:

11. The system of claim 10 , wherein the attenuation factor applied to the second data set corrects for the pulse pile-up effect.

12. The system of claim 10 , wherein the attenuation factor applied to the second data set corrects for the charge sharing effect.

13. The system of claim 10 , wherein the system comprises a first scanning device with the first detector array and a second scanning device with the second detector array.

14. The system of claim 10 , wherein the at least one scanning device comprises a computed tomography (CT) imaging device.

15. The system of claim 14 , wherein the x-ray source comprises an x-ray tube.

16. 16. The system of claim 15, wherein the x-ray beam emitted by the x-ray tube is a polychromatic x-ray beam.

17. The system of claim 10 , wherein the mathematical model is supplemented by extracting data from the second data set before deriving the damping coefficient.

18. 14. The system of claim 13, wherein the first scanning device and the second scanning device comprise identically configured computed tomography (CT) imaging devices.

19. 1. A method of calibrating an imaging device having a photon-counting detector (PCD), comprising: providing (i) an X-ray source configured to emit an X-ray beam; (ii) a first detector array configured to be aligned with the X-ray beam, the first detector array comprising a plurality of energy integrating detectors (EIDs) for detecting the X-ray beam emitted by the X-ray source; and (iii) a second detector array configured to be aligned with the X-ray beam, the second detector array comprising a plurality of photocounting detectors (PCDs) for detecting the X-ray beam emitted by the X-ray source; detecting an X-ray beam that has passed through an object scanned by the plurality of energy integrating detectors (EIDs); recording the X-ray beam that has passed through the object as scanned and detected by the plurality of energy integrating detectors (EIDs) as a first data set; detecting an X-ray beam that has passed through the object and is scanned by the plurality of photocounting detectors (PCDs); recording the X-ray beam that has passed through the object as scanned and detected by the plurality of photocounting detectors (PCDs) as a second data set; generating a mathematical model from the first data set and the second data set to derive a damping coefficient; applying the attenuation coefficient to the second data set to calibrate the imaging device; A method comprising:

20. 20. The method of claim 19, further comprising generating a data-driven model by extracting data from the second data set before deriving the damping coefficient.

21. 20. The method of claim 19, further comprising generating a scanned image of the object from the second data set after applying the attenuation coefficient to the second data set.

22. 20. The method of claim 19, wherein the attenuation factor applied to the second data set corrects for the pulse pile-up effect.

23. 20. The method of claim 19, wherein the attenuation factor applied to the second data set corrects for the charge sharing effect.

24. 20. The method of claim 19, wherein a scanning device comprises the first detector array and the second detector array.

25. 25. The method of claim 24, wherein the scanning device comprises a computed tomography (CT) imaging device.

26. 20. The method of claim 19, wherein a first scanning device comprises the first detector array and a second scanning device comprises the second detector array.

27. 27. The method of claim 26, wherein the first and second scanning devices comprise the same computed tomography (CT) imaging device.

Images