X-ray image capturing apparatus, program, and x-ray image correction method

Abstract

To provide an X-ray image capturing apparatus, a program, and an X-ray image correction method that can reduce advance preparation and improve image quality of images obtained by X-ray measurement.SOLUTION: An X-ray image capturing apparatus comprises an X-ray source 2, a detector 9 that detects X-rays emitted from the X-ray source 2, a control processing device 10 that corrects an output of the detector 9, and a storage device 11 that records the output of the detector 9 and stores parameter sets corresponding to attenuation lengths, reproducing, in a projection image, a scattered-ray distribution calculated by simulation. The control processing device 10 calculates an attenuation length on the basis of the output of the detector 9, estimates a distribution of scattered rays using the parameter set, and corrects the output of the detector 9.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an X-ray image capturing apparatus, a program, and an X-ray image correction method for correcting the influence of scattered rays that occur when capturing an X-ray image on the image. [Background technology]

[0002] Patent Document 1 describes a technology for correcting scattered X-rays with high accuracy and speed through simple advance preparation and processing calculations, thereby improving the quality of images obtained by X-ray measurement. The technology uses a pre-created correction function that associates measurement data with correction values ​​to correct the obtained measurement data for each pixel, and the correction is performed by substituting the correction value when it is obtained directly from the X-ray intensity, or by subtracting the correction value from the measurement data when it is obtained from the scattered X-ray intensity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-106433 Summary of the Invention [Problem to be solved by the invention]

[0004] X-ray imaging devices obtain still and moving images of a subject by irradiating the subject with X-rays and measuring the amount of X-rays that pass through. Since the amount of X-rays that pass through decreases as the density of the subject increases, density information of the subject can be obtained from the detected amount of X-rays.

[0005] When X-rays pass through a subject, scattered rays are generated. These scattered rays mix with direct X-rays, which are the true transmitted amount, and enter the detector that detects the X-rays, increasing the amount of detected X-rays beyond the true transmitted amount. As a result, the density of the subject is underestimated due to the effect of scattered rays, which results in a deterioration of image quality, and so it is desirable to address this issue.

[0006] In many cases, a grid is installed between the object and the detector in an X-ray imaging device to block scattered rays that are incident at angles different from those of direct X-rays.

[0007] However, increasing the shielding effect of the grid reduces the amount of X-rays incident on the detector, which reduces the signal-to-noise ratio of the image and degrades image quality. To avoid this degradation, it is necessary to increase the amount of X-rays irradiated onto the subject, but this increases the subject's exposure, so a different solution is desired.

[0008] To solve these problems, there is a technique for improving image quality by correcting scattered radiation components contained in a projected image, as in the above-mentioned Patent Document 1 and the like.

[0009] However, in the technology disclosed in Patent Document 1, an imaging test of a simulated subject is performed when creating a correction function, and this simulation test needs to be performed under multiple conditions, such as the voltage and current applied to the X-ray tube, whether the collimator is open or closed, etc. Therefore, since advance preparation requires time, improvements are desired.

[0010] Therefore, the present invention provides an X-ray image capturing apparatus, a program, and an X-ray image correcting method that can reduce advance preparations and improve the quality of images obtained by X-ray measurement. [Means for solving the problem]

[0011] The present invention includes a number of means for solving the above-described problems, and one example thereof includes an X-ray source, an X-ray detector that detects X-rays emitted from the X-ray source, a correction processing unit that corrects the output of the X-ray detector, and a recording unit that records the output of the X-ray detector and stores a parameter set according to the attenuation length that reproduces the scattered ray distribution calculated by simulation in a projection image, wherein the correction processing unit calculates the attenuation length based on the output of the X-ray detector, estimates the scattered ray distribution using the parameter set, and corrects the output of the X-ray detector. [Effects of the Invention]

[0012] According to the present invention, it is possible to reduce the amount of preparation required in advance and improve the quality of images obtained by X-ray measurement. Objects, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a side view of an X-ray imaging apparatus according to a first embodiment. [Figure 2] FIG. 3 is a flowchart of X-ray image correction according to the first embodiment. [Figure 3] 4 is a flowchart of calculation of X-ray image processing parameters in the X-ray image correcting method according to the first embodiment. [Figure 4A] 1 shows the scattered radiation distribution and cross-sectional profile for a uniform subject. [Figure 4B] 1 shows a cross-sectional profile for a uniform object. [Figure 5] FIG. 10 is another flowchart of the X-ray image processing parameter calculation in the X-ray image correcting method according to the first embodiment. [Figure 6] 3 is a flowchart of X-ray image processing in the X-ray image correction method according to the first embodiment. [Figure 7] FIG. 11 is a flowchart of X-ray image processing parameter calculation using a simulated human body in the X-ray image correction method according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the X-ray imaging device, the program, and the X-ray image correction method of the present invention will be described with reference to the drawings. In the drawings used in this specification, identical or similar reference numerals are used to designate identical or corresponding components, and repeated explanations of these components may be omitted.

[0015] First Embodiment A first embodiment of an X-ray imaging apparatus, a program, and an X-ray image correcting method according to the present invention will be described with reference to FIGS.

[0016] First, the overall configuration of the X-ray imaging apparatus will be described with reference to Fig. 1. Fig. 1 is a side view of the X-ray imaging apparatus according to the first embodiment.

[0017] The X-ray imaging device shown in Figure 1 includes an X-ray tube 1 having an X-ray source 2, a detector 9 that detects X-rays emitted from the X-ray source 2, a support 4, a rotation device 5, a subject holding device 7, a control processing device 10 that corrects the output of the detector 9, a recording device 11, an input / output device 12, etc.

[0018] An X-ray source 2 in an X-ray tube 1 irradiates an object 6 with X-rays. The X-rays that pass through the object 6 are detected by a detector 9, which will be described later. There are no particular restrictions on the type of X-ray source 2, but for example, a device that generates X-rays by applying a high voltage to thermions emitted by passing an electric current through a filament and causing them to collide with a target is used. The energy of the X-rays irradiated from the X-ray source 2 is the energy that passes through the object 6, and when the object 6 is a human body, it is typically tens to hundreds of kiloelectron volts.

[0019] A collimator 3 for adjusting the range of X-rays irradiated onto the subject 6 may be installed between the X-ray source 2 and the subject 6. There are no restrictions on the material of the collimator 3, but lead is often used as a material that effectively blocks X-rays.

[0020] The detector 9 detects X-rays emitted from the X-ray source 2 and transmitted through the subject 6, converts them into electrical signals according to their intensity, and inputs them as a measurement image to a control and processing device 10 (described later). There are no particular limitations on the type of detector 9, but in this embodiment, a two-dimensional detector is used. A two-dimensional detector also includes a multi-row arrangement of one-dimensional detectors. Examples of two-dimensional detectors include a flat X-ray detector, a combination of an X-ray image intensifier and a CCD camera, an imaging plate, a CCD detector, a solid-state detector, and a semiconductor detector. A grid 8 for blocking scattered radiation may be installed between the detector 9 and the subject 6.

[0021] The rotation device 5 rotates the X-ray source 2 and detector 9 in the X-ray tube 1, which are connected by the support 4, around the subject. There are no particular limitations on the form of the rotation device 5 and the support 4, and for example, a gantry may be used.

[0022] The subject holding device 7 holds the subject 6 during X-ray image acquisition. In this embodiment, the subject holding device 7 is a bed, but the form is not limited thereto, and for example, a chair may be used. In this case, the rotation device 5 rotates around the subject 6 in a plane parallel to the floor.

[0023] The control processing device 10 is an information processing device equipped with a CPU (Central Processing Unit), memory, GPU (Graphics Processing Unit), etc., and has the following functions: a measurement control unit that controls the operation of each part of the X-ray image capturing device to perform measurements and obtain a measurement image, and a correction processing unit that performs correction processing on the measurement image to obtain a corrected image.

[0024] For example, the measurement control unit controls the generation of X-rays in the X-ray source 2, the acquisition of data in the detector 9, and the rotation of the support 4 in the rotation device 5, thereby realizing rotational measurement in which X-rays are irradiated and a measurement image is acquired while rotating the support 4. In this case, the correction processing unit of the control processing device 10 performs reconstruction processing on the corrected image and acquires a 3D reconstructed image.

[0025] In this embodiment, the correction processing unit of the control processing device 10 performs calculations on the measurement data using the parameters stored in the recording device 11 to obtain correction data. In this embodiment, the parameters are used to estimate the scattered ray components contained in the X-ray measurement data, and the scattered ray components are subtracted from the measurement data to obtain correction data.

[0026] Specifically, the correction processing unit of the control processing device 10 calculates the attenuation length based on the output of the detector 9, estimates the distribution of scattered radiation using the parameter set, and corrects the output of the detector 9. The amount of scattered radiation can also be estimated using the parameter set. Furthermore, the control processing device 10 can calculate the parameter set based on the patient image and store it in the recording device 11. These details will be described later.

[0027] This control processing device 10 preferably performs the steps of calculating the attenuation length from the output results of the detector 9, reproducing the scattered radiation distribution calculated by simulation in a projection image, storing a parameter set corresponding to the attenuation length, and estimating the scattered radiation distribution using the parameter set and correcting the output of the detector 9.

[0028] The recording device 11 is configured with a recording medium such as an HDD, SSD, flash memory, etc. The recording device 11 records parameters used in the correction process, specifically, the output of the detector 9, and also stores a parameter set according to the attenuation length that reproduces the scattered radiation distribution calculated by simulation in the control processing device 10 as a projection image.

[0029] Therefore, in this embodiment, the recording device 11 stores software that causes the control processing device 10, which is a processing device, to execute the following steps: calculating the attenuation length from the output results of the detector 9; reproducing the scattered radiation distribution calculated by simulation in a projection image, storing a parameter set corresponding to the attenuation length; and estimating the scattered radiation distribution using the parameter set and correcting the output of the detector 9.

[0030] It is possible to record in advance in the recording device 11 measurement data of a simulated human body or the like for reference, as will be described later, parameter sets created from numerical simulations, and the like.

[0031] The control processes for the operations to be executed may be integrated into one program, or may be divided into multiple programs, or may be a combination of these.

[0032] Some or all of the programs stored in each device may be implemented using dedicated hardware or may be modularized. Furthermore, various programs may be installed in each device via a program distribution server or external storage media, or may be used to update existing devices.

[0033] Furthermore, each device may be an independent device connected via a wired or wireless network, or two or more devices may be integrated together.

[0034] The input / output device 12 is composed of a pointing device such as a keyboard or a mouse, and a display device such as a liquid crystal display. It is also possible to configure the device as a touch panel type display that also serves as an input / output device.

[0035] The flow of processing in the X-ray imaging apparatus according to the embodiment of the present invention, that is, the outline of the procedure of the X-ray image correction method, will be described below with reference to FIG.

[0036] First, the overall flow of correction according to the first embodiment will be described with reference to Fig. 2.

[0037] As shown in FIG. 2, first, as a preliminary step, X-ray image (measurement data) processing parameters for each attenuation length L are calculated using a simulation (step S0).

[0038] Here, the attenuation length L is the distance over which the X-ray intensity, expressed by the following formula (1), becomes 1 / e of the incident intensity.

[0039]

number

[0040] In equation (1), μ is the linear attenuation coefficient, I0 is the intensity of the incident X-rays irradiated from the X-ray source, and I is the intensity of the X-rays detected by the detector, i.e., the measurement data. Specific methods for calculating the parameters will be described later. The calculated parameters are stored in the recording device 11 in the form of a table or the like, and are read out as necessary when performing correction.

[0041] Next, the procedure on the day of treatment will be described.

[0042] On the day of treatment, multiple X-ray images of the patient are taken (step S1). The X-ray source 2 and detector 9 rotate around the subject 6 using the rotation device 5 shown in Figure 1, capturing images at regular angles. The imaging angle interval is typically 1 degree or less, and the number of images taken is the number required to obtain a 3D reconstructed image through reconstruction processing, typically several hundred.

[0043] Next, the control processing device 10 calculates the attenuation length L of the subject at each pixel from the obtained X-ray image using equation (1) (step S2).

[0044] Next, the control processing device 10 reads out the parameters corresponding to the attenuation length of each pixel obtained in step S2 from the recording device 11, which parameters were calculated and recorded in step S0 as a preliminary step (step S3).

[0045] Next, the control processing device 10 processes the X-ray image using the parameters read out in step S3 to estimate the scattered radiation component (step S4). A specific method for processing the image will be described later.

[0046] Next, the control processing device 10 performs a correction process to subtract the estimated scattered ray component from the X-ray image (step S5). By this calculation, the influence of scattered rays contained in the X-ray image is corrected.

[0047] Next, details of the processing of each of the above steps will be explained with reference to Figures 3 to 5. First, the procedure of the preliminary processing parameter calculation step in Figure 2 will be explained with reference to Figures 3 to 4B. Figure 3 is a flow diagram of X-ray image processing parameter calculation according to the first embodiment, Figure 4A is a diagram showing the scattered ray distribution for a uniform subject according to the first embodiment, and Figure 4B is a diagram showing a cross-sectional profile.

[0048] First, as shown in Fig. 3, a treatment planning CT image of the patient is taken about one week before treatment (step S10), and the control processing device 10 performs an X-ray image acquisition simulation based on the three-dimensional reconstructed image of the patient taken by the planning CT (step S11). In this way, measurement data from the planning CT of the patient himself, who is the imaging target, can be used in the simulation. Note that the timing of the treatment planning CT imaging of the patient is just an example, and can be set appropriately depending on the patient and the condition of the treatment.

[0049] In the simulation, the X-ray imaging system on the day of treatment, as shown in Figure 1, is reproduced, the interaction between the X-rays emitted from the X-ray source and the patient's body, which is the subject, is calculated, and the X-rays that finally enter the detector are recorded as the obtained X-ray image.

[0050] At this time, the X-rays scattered by the subject and then incident on the detector are recorded independently. This is called the correct scattered radiation distribution corresponding to the X-ray image. The control processing device 10 calculates a pair of the X-ray image and the corresponding correct scattered radiation distribution for each imaging angle interval taken on the day of treatment, and records them in the recording device 11 (step S11).

[0051] Next, the control processing device 10 processes the X-ray image obtained by the simulation in step S11 above, and reproduces the scattered ray distribution corresponding to the X-ray image.

[0052] Fig. 4A shows the scattered radiation distribution for a uniform subject according to the first embodiment, and Fig. 4B shows its transverse profile. As shown in Fig. 4A, scattered radiation is generated isotropically around the point of X-ray irradiation, and as shown in Fig. 4B, its profile can be well approximated by a two-dimensional Gaussian function. Based on this fact, the X-ray image is convoluted with a two-dimensional Gaussian function expressed by the following equation (2), blurring the X-ray projection image and reproducing the scattered radiation distribution by estimating it (step S12).

[0053]

number

[0054] Equation (2) is a two-dimensional Gaussian function that models the spread of scattered radiation when a uniform object is irradiated with a point X-ray. (x, y) are the coordinates of the pixel in the projection image, the y-axis is the body axis direction of the object, and the x-axis is the direction perpendicular to the y-axis. A is the amplitude of the Gaussian function, B is the offset, and σ is the parameter for the width of the Gaussian function.

[0055] In this way, the control processing device 10 can estimate the distribution and amount of scattered radiation using the parameter set and correct the output of the detector 9. In addition, the scattered radiation distribution can be approximated by a Gaussian function, and the parameter set can be the amplitude, offset, and width of the Gaussian function.

[0056] Next, the control processing device 10 determines the parameters of the two-dimensional Gaussian function that will bring the scattered radiation distribution closest to the blurred image obtained in step S12 (step S13).

[0057] Specifically, P in the following formula (3) i (x i ,y i ) is the i-th pixel value of the X-ray image, and the operator represents the convolution calculation. S obtained by the calculation of Eq. (3) irepresents the estimated scattered radiation amount of the i-th pixel, and the parameters A, B, and σ are calculated by optimization so that the estimated scattered radiation distribution obtained by this calculation is closest to the correct scattered radiation corresponding to the X-ray image obtained by simulation.

[0058]

number

[0059] The above optimization calculation is performed for each image at every imaging angle. The obtained parameters are stored in the recording device 11 in a table format.

[0060] The procedure of the processing parameter calculation step in Fig. 2 is not limited to the procedure shown in Fig. 3 above, but may be the procedure shown in Fig. 5. Fig. 5 shows another example of a flow of advance processing parameter calculation according to this embodiment.

[0061] First, as shown in FIG. 5, a treatment planning CT image of a simulated human body is captured (step S10A), and the control processing device 10 performs an X-ray image capturing simulation based on a three-dimensional reconstructed image of the treatment planning CT of the simulated human body captured in advance in step S10A, instead of based on a three-dimensional reconstructed image of the patient's planning CT captured as in step S11 shown in FIG. 3 (step S11A).

[0062] In this way, measurement data from the planned CT scan of the simulated human body can be used in the simulation. In this case, the CT images of the simulated human body can be recorded in advance during the manufacturing stage, or can be taken each time.

[0063] Thereafter, steps S12 and S13 shown in FIG. 3 are executed.

[0064] Next, a method of processing an X-ray image using parameters, among step S4 of the X-ray image processing in Fig. 2, will be described with reference to Fig. 6. Fig. 6 is a flow chart of the X-ray image processing according to the first embodiment.

[0065] First, as shown in Fig. 6, the control processing device 10 calculates the attenuation length L of each pixel of the X-ray image captured on the day of treatment (step S21). Equation (1) is used to calculate the attenuation length.

[0066] Next, the control processing device 10 calculates the parameter A in equation (2) corresponding to the attenuation length of the i-th pixel. i ,B i ,σ i is read out from the table stored in the recording device 11 (step S22). This is repeated for all pixels.

[0067] Next, the control processing device 10 performs a convolution calculation on the X-ray image with the two-dimensional Gaussian function to which the read parameters have been applied (step S23). The image obtained by this calculation is an estimated scattered ray distribution corresponding to the X-ray image.

[0068] Finally, the control processing device 10 performs this calculation for all X-ray images taken on the day of treatment. By processing the X-ray images taken on the day of treatment in this manner, it is possible to estimate the scattered ray distribution for the X-ray images (step S24).

[0069] Next, the effects of the embodiment will be described.

[0070] The X-ray imaging device of the first embodiment of the present invention described above comprises an X-ray source 2, a detector 9 that detects X-rays emitted from the X-ray source 2, a control processing device 10 that corrects the output of the detector 9, and a recording device 11 that records the output of the detector 9 and stores a parameter set according to the attenuation length that reproduces the scattered ray distribution calculated by simulation in a projection image.The control processing device 10 calculates the attenuation length based on the output of the detector 9, estimates the scattered ray distribution using the parameter set, and corrects the output of the detector 9.

[0071] In addition, the program executed by the processing device of the X-ray imaging device of the first embodiment of the present invention causes the processing device to execute the following steps: calculating the attenuation length from the output results of the detector 9; reproducing the scattered ray distribution calculated by simulation in a projection image, storing a parameter set corresponding to the attenuation length; and estimating the scattered ray distribution using the parameter set and correcting the output of the detector 9.

[0072] Furthermore, the X-ray image correction method of the first embodiment of the present invention includes a step of calculating the attenuation length from the output result of the detector 9, a step of reproducing the scattered ray distribution calculated by simulation in a projection image, a step of storing a parameter set according to the attenuation length, and a step of estimating the scattered ray distribution using the parameter set and correcting the output of the detector 9.

[0073] By calculating the X-ray image processing parameters according to the attenuation length L through simulation in this way, it is possible to improve the image quality of images obtained by X-ray measurement compared to conventional methods, without the need for complicated advance preparations.

[0074] Furthermore, the control processing device 10 calculates the parameter set based on the patient image and stores it in the recording device 11, which reduces the amount of processing that needs to be done on the day of treatment using X-ray images, thereby shortening the treatment time.

[0075] Furthermore, the control processing device 10 can further improve the accuracy of calculating the scattered radiation distribution by estimating the amount of scattered radiation using the parameter set.

[0076] Furthermore, by using measurement data from the planning CT scan of the patient, who is the subject of imaging, in the simulation, it becomes possible to perform correction processing with higher accuracy according to the actual condition of the subject.

[0077] Furthermore, by using measurement data from a planning CT scan of a simulated human body in the simulation, processing parameters can be created at any timing, regardless of the timing of the patient's treatment.

[0078] Furthermore, by approximating the scattered radiation distribution with a Gaussian function and using the amplitude, offset, and width of the Gaussian function as the parameter set, the accuracy of approximating the scattered radiation distribution can be improved.

[0079] Second Embodiment An X-ray imaging apparatus, a program, and an X-ray image correcting method according to a second embodiment of the present invention will be described with reference to FIG.

[0080] The X-ray image capturing apparatus, program, and X-ray image correcting method of this embodiment are basically the same as those of the first embodiment.

[0081] The difference is that in the first embodiment, a simulation was performed using a three-dimensional reconstructed image of the patient taken about one week before treatment, such as a planning CT scan, to determine the correction parameters, whereas in this embodiment, a parameter set is recorded in advance in the recording device 11, and a simulation is performed using a numerical phantom created on a computer to determine the correction parameters.

[0082] The following description will focus on the configuration that differs from the first embodiment. In the following embodiments, the same components as those in the first embodiment will be designated by the same reference numerals.

[0083] The flow of the pre-processing parameter calculation step of this embodiment will be described with reference to Fig. 7. Fig. 7 is a flow diagram of X-ray image processing parameter calculation using a numerical phantom according to the second embodiment.

[0084] First, as shown in Fig. 7, the control processing device 10 creates a numerical phantom on a computer (step S10B). The types of numerical phantoms used in the simulation include phantoms that simulate the human body, which is the subject, such as phantoms that simulate the human body, cylindrical phantoms, and elliptical cylindrical phantoms. To accommodate variations in patient body shapes, these numerical phantoms are created with multiple thicknesses (multiple radii, minor radii, and major radii for cylindrical and elliptical cylindrical phantoms).

[0085] Next, the control processing device 10 performs an X-ray image capturing simulation on the created numerical phantom, and obtains an X-ray image of the numerical phantom and the corresponding correct scattered radiation distribution (step S11B).

[0086] The outline of the subsequent simulation, the system, the number of images taken, and the parameter calculation method by processing the X-ray images (steps S12 and S13) are the same as those in the first embodiment described with reference to FIG. 3 or FIG.

[0087] Next, we explain how to process X-ray images using parameters created using a numerical phantom.

[0088] First, the control processing device 10 calculates the attenuation length L of each pixel of the X-ray image captured on the day of treatment. The attenuation length is calculated using equation (1).

[0089] Next, the control processing device 10 reads out the parameters of a numerical phantom having a thickness or diameter that has an attenuation length closest to the calculated attenuation length L.

[0090] Thereafter, the control processing device 10 uses the read parameters to estimate the scattered radiation distribution in the same manner as in the first embodiment.

[0091] The other configurations and operations are substantially the same as those of the X-ray image pickup apparatus, program, and X-ray image correction method of the first embodiment described above, and details thereof will be omitted.

[0092] The X-ray image capturing apparatus, program, and X-ray image correcting method of the second embodiment of the present invention also provide substantially the same effects as the X-ray image capturing apparatus, program, and X-ray image correcting method of the first embodiment described above.

[0093] Furthermore, since the parameter set is pre-recorded in the recording device 11, the X-ray image processing parameters can be calculated by operating only on a computer without taking a planned CT scan in advance, thereby reducing the complexity of advance preparations.

[0094] Furthermore, by using a numerical phantom in the simulation, it is possible to calculate the processing parameters with high accuracy in advance.

[0095] Furthermore, by using a cylindrical numerical phantom in the simulation, processing parameters can be calculated without taking a long time for calculation processing.

[0096] Furthermore, by using a numerical phantom that simulates a human body in the simulation, it is possible to realize pre-calculation in a state that more closely resembles the imaging target.

[0097] Furthermore, by using an elliptical cylindrical numerical phantom for the simulation, pre-calculation can be performed faster than when using a numerical phantom that simulates a human body, and with higher accuracy than when using a cylindrical numerical phantom.

[0098] <Other> It should be noted that the present invention is not limited to the above-described embodiment, and includes various modifications. The above-described embodiment has been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to an embodiment having all of the described configurations.

[0099] It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment, or to add, delete, or replace part of the configuration of each embodiment with the configuration of another embodiment. [Explanation of symbols]

[0100] 1...X-ray tube 2...X-ray source 3...Collimator 4…Strut 5...Rotating device 6...Subject 7…Subject holding device 8...Grid 9...Detector (X-ray detector) 10...Control processing device (correction processing unit) 11...Recording device 12... Input / output device

Claims

1. an X-ray source; an X-ray detector that detects X-rays emitted from the X-ray source; a correction processing unit that corrects the output of the X-ray detector; a recording unit that records the output of the X-ray detector and stores a parameter set according to an attenuation length that reproduces the scattered radiation distribution calculated by simulation in a projection image, The correction processing unit Calculating an attenuation length based on the output of the X-ray detector; The distribution of scattered rays is estimated using the parameter set, and the output of the X-ray detector is corrected. X-ray imaging device.

2. 2. The X-ray imaging apparatus according to claim 1, The correction processing unit calculates the parameter set based on the patient image and stores the parameter set in the recording unit. X-ray imaging device.

3. 2. The X-ray imaging apparatus according to claim 1, The parameter set is pre-recorded in the recording unit. X-ray imaging device.

4. 4. The X-ray imaging apparatus according to claim 1, The correction processing unit also estimates the amount of scattered radiation using the parameter set. X-ray imaging device.

5. 2. The X-ray imaging apparatus according to claim 1, The simulation uses measurement data from a planning CT scan of the patient who is the imaging target. X-ray imaging device.

6. 6. The X-ray imaging apparatus according to claim 5, The simulation uses measurement data from a planning CT scan of a simulated human body. X-ray imaging device.

7. 2. The X-ray imaging apparatus according to claim 1, A numerical phantom is used in the simulation. X-ray imaging device.

8. 2. The X-ray imaging apparatus according to claim 1, A cylindrical numerical phantom is used for the simulation. X-ray imaging device.

9. 9. The X-ray imaging apparatus according to claim 8, A numerical phantom that simulates the human body is used for the simulation. X-ray imaging device.

10. 9. The X-ray imaging apparatus according to claim 8, A numerical phantom of an elliptical cylinder is used for the simulation. X-ray imaging device.

11. 2. The X-ray imaging apparatus according to claim 1, The scattered radiation distribution is approximated by a Gaussian function, and the parameter set is the amplitude, offset, and width of the Gaussian function. X-ray imaging device.

12. A program to be executed by a processing device of an X-ray imaging device, calculating an attenuation length from the output of the X-ray detector; A step of reproducing the scattered radiation distribution calculated by simulation in a projection image and storing a parameter set according to the attenuation length; and a step of estimating a distribution of scattered rays using the parameter set and correcting the output of the X-ray detector. software.

13. calculating an attenuation length from the output of the X-ray detector; a step of reproducing the scattered radiation distribution calculated by the simulation as a projection image and storing a parameter set according to the attenuation length; and a step of estimating a distribution of scattered rays using the parameter set and correcting the output of the X-ray detector. X-ray image correction method.

Images