X-ray diagnostic equipment and medical image processing equipment

Abstract

To generate a medical image in which artifacts due to saturation are reduced.SOLUTION: An X-ray diagnostic device includes a first reading part, a second reading part, an acquisition part, an estimation part, and a correction part. The first reading part causes an X-ray detector to execute non-destructive reading of signals accumulated in an X-ray detection element before ending X-ray exposure. The second reading part causes the X-ray detector to execute destructive reading of signals accumulated in the X-ray detection element after X-ray exposure. The acquisition part acquires first projection data generated on the basis of the signals read by the non-destructive reading, and acquires second projection data generated on the basis of the signals read by destructive reading. The estimation part estimate a saturation region in which saturation is occurring on the basis of the second projection data. The correction part replaces signals in the saturation region in the second projection data with signals in the saturation region in the first projection data.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005] , , ,

[0001] The embodiments disclosed in this specification and the drawings relate to an X-ray diagnostic apparatus and a medical image processing apparatus.

Background Art

[0002] In an X-ray diagnostic apparatus, an X-ray detector (FPD) for pulse-irradiating X-rays and reading out an image is used. For example, the charge signal accumulated in the X-ray detector during intermittently irradiated X-ray pulses is read out, and an X-ray image is created based on the read charge signal.

[0003] In such an X-ray diagnostic apparatus, when the X-ray detector directly receives the X-rays, the dose of the X-rays incident on the X-ray detector may exceed the maximum incident dose of the X-ray detector, and saturation may occur. When saturation occurs, a correct signal value cannot be read from the X-ray detector. For this reason, the generated X-ray image may not have correct pixel values, and artifacts may occur in the generated X-ray image. As a countermeasure, a method of estimating the value of the signal in the saturation region and performing saturation correction is known. In such a method, it is difficult to accurately estimate and correct the incident dose in the saturation region.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One of the problems that the embodiments disclosed herein and in the drawings aim to solve is the generation of medical images with reduced artifacts caused by saturation. However, the problems that the embodiments disclosed herein and in the drawings aim to solve are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0006] The X-ray diagnostic apparatus according to the embodiment comprises a first readout unit, a second readout unit, an acquisition unit, an estimation unit, and a correction unit. The first readout unit causes the X-ray detector to non-destructively read out the signal accumulated in the X-ray detection element before the end of X-ray exposure. The second readout unit causes the X-ray detector to destructively read out the signal accumulated in the X-ray detection element after the end of X-ray exposure. The acquisition unit acquires first projection data generated based on the signal read out by non-destructive readout and second projection data generated based on the signal read out by destructive readout. The estimation unit estimates the saturation region where saturation is occurring based on the second projection data. The correction unit replaces the signal of the saturation region in the second projection data with the signal of the saturation region in the first projection data. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 shows an example of the configuration of an X-ray diagnostic apparatus according to an embodiment. [Figure 2] Figure 2 is a flowchart illustrating the processing procedure for image generation by the X-ray diagnostic apparatus according to the embodiment. [Figure 3] Figure 3 is a diagram illustrating the timing of signal readout performed by the image generation process of the X-ray diagnostic apparatus according to the embodiment. [Figure 4] Figure 4 is a diagram illustrating the processing flow from the image generation process by the X-ray diagnostic apparatus according to the embodiment until a saturation-corrected image is generated. [Figure 5]Figure 5 is a flowchart illustrating the processing procedure for image generation using an X-ray diagnostic device according to the first modified example. [Figure 6] Figure 6 is a diagram illustrating the processing flow from the image generation process by the X-ray diagnostic device according to the first modified example until a saturation-corrected image is generated. [Figure 7] Figure 7 is a diagram illustrating the timing of signal readout performed by the image generation process of the X-ray diagnostic apparatus according to the fourth modified example. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments of the X-ray diagnostic apparatus and medical image processing apparatus will be described in detail with reference to the drawings. In the following description, components having substantially the same function and configuration will be denoted by the same reference numeral, and redundant explanations will be given only when necessary.

[0009] (Embodiment) Figure 1 is a diagram showing an example of the configuration of an X-ray diagnostic apparatus 1 according to an embodiment. As shown in Figure 1, the X-ray diagnostic apparatus 1 comprises an imaging device 10, a patient table device 30, and a console device 40. The imaging device 10 comprises a high-voltage generator 11, an X-ray generator 12, an X-ray detector 13, a C-arm 14, and a C-arm drive device 142. The X-ray diagnostic apparatus 1 is a cone-beam CT apparatus (CBCT apparatus) that irradiates the subject P with a cone-beam shaped X-ray having a predetermined width in the axial direction of the body.

[0010] The high-voltage generator 11 generates a high voltage to be applied between the anode and cathode in order to accelerate thermionic electrons generated from the cathode of the X-ray tube, and outputs it to the X-ray tube.

[0011] The X-ray generating unit 12 includes an X-ray tube for irradiating the subject P with X-rays, a plurality of filters (hereinafter referred to as additional filters) that have the function of attenuating or reducing the amount of irradiated X-rays, and an X-ray diaphragm. The X-ray generating unit 12 irradiates the subject P with a cone-beam-shaped X-ray having a predetermined width in the axial direction of the subject P.

[0012] An X-ray tube is a vacuum tube that generates X-rays. An X-ray tube comprises a tube, a filament (cathode) located within the tube, and a tungsten anode. The X-ray tube accelerates thermionic electrons emitted from the filament using a high voltage. The X-ray tube generates X-rays by colliding these accelerated electrons with the tungsten anode. Furthermore, the X-ray tube is a vacuum tube that generates a cone-beam of X-rays, which has a conical or pyramidal spread along the body axis of the subject P.

[0013] The X-ray diaphragm is located between the X-ray tube and the X-ray detector 13 and is composed of a lead plate as a metal plate. The X-ray diaphragm adjusts the size of the X-ray irradiation area (X-ray field of view) (hereinafter referred to as the field of view size) by shielding X-rays outside the aperture area, thereby focusing the X-rays generated by the X-ray tube so that they are irradiated only to the region of interest of the subject P. For example, the X-ray diaphragm has four diaphragm blades, and the field of view size is adjusted by sliding these blades to adjust the area that is shielded by the X-rays to an arbitrary size. The diaphragm blades of the X-ray diaphragm are driven by a drive device (not shown) according to the region of interest input by the operator through the input interface 43.

[0014] The X-ray detector 13 detects X-rays emitted from the X-ray tube and transmitted through the subject P. Such an X-ray detector 13 can be either one that directly converts X-rays into electric charge or one that converts them into light first and then into electric charge. While the former is used as an example here, the latter is also acceptable. Specifically, the X-ray detector 13 includes, for example, a flat panel detector (FPD) that converts and stores the X-rays transmitted through the subject P into electric charge, and a gate driver that generates drive pulses to read out the charge stored in the FPD. The FPD is constructed by arranging minute detection elements two-dimensionally in the column and line directions. Each detection element includes a photoelectric film that senses X-rays and generates charge according to the amount of incident X-rays, a charge storage capacitor that stores the charge generated in the photoelectric film, and a thin-film transistor (TFT) that outputs the charge stored in the charge storage capacitor at predetermined timings. The stored charge is sequentially read out by drive pulses supplied by the gate driver. The X-ray detector 13 is an example of an X-ray detection unit. A projection data generation circuit (not shown) is provided downstream of the X-ray detector 13. The projection data generation circuit includes a parallel-to-serial converter that converts digital signals read out in parallel row or column by row from the FPD of the X-ray detector 13 into a time-series serial signal (time-series projection data). The time-series projection data is output from the projection data generation circuit and supplied to the console device 40.

[0015] In this embodiment, as the X-ray detector 13, a detector capable of performing both destructive readout and non-destructive readout is used. The destructive readout method is a method in which a signal accumulated in an X-ray detection element composed of a semiconductor element such as a photodiode is transferred to an integrating amplifier via a signal line, and an output signal corresponding to the signal integrated by the integrating amplifier is read out. Since the signal in the semiconductor element becomes empty by the transfer of the signal, this method is called destructive readout. On the other hand, the non-destructive readout method is a method in which an amplifier for converting a signal into an output signal is provided for each semiconductor element, and an output signal corresponding to the accumulated signal is read out while the signal is held in the X-ray detection element. Since the signal accumulated in the X-ray detection element is not emptied but held even after readout, this method is called non-destructive readout. In this embodiment, the destructive readout function after the end of X-ray irradiation that the X-ray detector 13 has as a default is called the normal readout function.

[0016] The C-arm 14 holds the X-ray generator 12 and the X-ray detector 13 and is configured to perform X-ray imaging while rotating. The C-arm 14 has a configuration in which the X-ray generator 12 and the X-ray detector 13 are held so as to face each other with the subject P and the top plate 33 interposed therebetween, and thus X-ray imaging of the subject P on the top plate 33 can be performed. The C-arm 14 is supported so as to be slidable and rotatable about each of a plurality of rotation axes. The C-arm 14 is provided with a plurality of power sources for realizing operations related to sliding and rotation at appropriate locations corresponding thereto. These power sources constitute the C-arm drive device 142. The C-arm drive device 142 reads a drive signal from the drive control function 442 and moves the C-arm 14 in a sliding motion, a rotational motion, and a linear motion. The C-arm 14 is an example of a support arm.

[0017] The bed device 30 is a device for placing and moving the subject P, and includes a base 31, a bed drive device 32, a top plate 33, and a support frame 34.

[0018] The base 31 is a housing installed on the floor surface and supporting the support frame 34 so as to be movable in the vertical direction (Z direction).

[0019] The bed driving device 32 is a motor or actuator that is housed within the housing of the bed device 30 and moves the top plate 33 on which the subject P is placed in the longitudinal direction (Y direction) of the top plate 33. The bed driving device 32 reads the driving signal from the drive control function 442 and moves the top plate 33 in the horizontal or vertical direction with respect to the floor surface. When the C-arm 14 or the top plate 33 moves, the positional relationship of the imaging axis with respect to the subject P changes. Note that the bed driving device 32 may move the support frame 34 in the longitudinal direction of the top plate 33 in addition to the top plate 33.

[0020] The top plate 33 is provided on the upper surface of the support frame 34 and is a plate on which the subject P is placed.

[0021] The support frame 34 is provided on the upper part of the base 31 and supports the top plate 33 so as to be slidable along its longitudinal direction.

[0022] Note that the bed device 30 may be such that the top plate 33 is movable with respect to the support frame 34, or the top plate 33 and the support frame 34 may be movable together with respect to the base 31.

[0023] The console device 40 includes a memory 41, a display 42, an input interface 43, and a processing circuit 44. Although the console device 40 is described as being separate from the imaging device 10, the imaging device 10 may include the console device 40 or a part of each component of the console device 40. The console device 40 corresponds to, for example, a medical image processing device.

[0024] Hereinafter, the console device 40 is described as executing a plurality of functions with a single console, but it may be that different consoles execute the plurality of functions. For example, the functions of the processing circuit 44 such as the image generation function 450 described later may be distributed and mounted on different console devices.

[0025] Memory 41 is a storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive), or integrated circuit that stores various types of information. Memory 41 may also be a portable storage medium other than an HDD or SSD, such as a CD (Compact Disc), DVD (Digital Versatile Disc), or flash memory. Furthermore, memory 41 may be a drive device that reads and writes various types of information to and from semiconductor memory elements such as flash memory or RAM (Random Access Memory). The storage area of ​​memory 41 may be located within the console device 40 or in an external storage device connected via a network.

[0026] Memory 41 stores programs executed by the processing circuit 44, various data used in the processing of the processing circuit 44, etc. As a program, for example, a program is used that is pre-installed on the computer from a network or a non-transient computer-readable storage medium, and that enables the computer to implement each function of the processing circuit 44. The various data dealt with in this specification are typically digital data. Memory 41 is an example of a storage unit.

[0027] The display 42 displays various types of information. For example, the display 42 outputs medical images (X-ray images) generated by the processing circuit 44, or a GUI (Graphical User Interface) for receiving various operations from the operator. For example, the display 42 is a liquid crystal display or a CRT (Cathode Ray Tube) display. The display 42 may be provided on the imaging device 10. The display 42 may also be a desktop type, or it may be composed of a tablet terminal that can communicate wirelessly with the console device 40. The display 42 is just one example of a display unit.

[0028] The input interface 43 receives various input operations from the operator, converts the received input operations into electrical signals, and outputs them to the processing circuit 44. For example, the input interface 43 receives operations from the operator for scanning conditions when acquiring projection data, reconstruction conditions, movement instructions for the C-arm 14, setting of regions of interest (ROI), and performing fluoroscopy. For example, the input interface 43 can be implemented by a mouse, keyboard, trackball, switch buttons, joystick, touchscreen integrating a display screen and touchpad, non-contact input circuit using an optical sensor, and audio input circuit for performing various processes of the processing circuit 44. The input interface 43 is connected to the processing circuit 44 and converts the input operations received from the operator into electrical signals and outputs them to the control circuit. In this specification, the input interface is not limited to those equipped with physical operating components such as a mouse or keyboard. For example, an electrical signal processing circuit that receives electrical signals corresponding to input operations from an external input device provided separately from the device and outputs these electrical signals to the processing circuit 44 is also included as an example of an input interface. Furthermore, the input interface 43 may be provided on the imaging device 10, or it may consist of a tablet terminal or the like that can communicate wirelessly with the console device 40. The input interface 43 is an example of an input unit.

[0029] The processing circuit 44 controls the operation of the entire X-ray diagnostic apparatus 1. The processing circuit 44 is a processor that executes system control functions 441, drive control functions 442, X-ray control functions 443, normal readout functions 444, non-destructive readout functions 445, projection data acquisition functions 446, estimation functions 447, normalization functions 448, correction functions 449, image generation functions 450, and display control functions 451 by calling and executing programs in memory 41.

[0030] In Figure 1, it is explained that a single processing circuit 44 implements the system control function 441, drive control function 442, X-ray control function 443, normal readout function 444, non-destructive readout function 445, projection data acquisition function 446, estimation function 447, normalization function 448, correction function 449, image generation function 450, and display control function 451, but this is not limited to this. For example, a processing circuit may be configured by combining multiple independent processors, and each processor may implement each function by executing a program. Furthermore, the system control function 441, drive control function 442, X-ray control function 443, normal readout function 444, non-destructive readout function 445, projection data acquisition function 446, estimation function 447, normalization function 448, correction function 449, image generation function 450, and display control function 451 may also be called the system control circuit, drive control circuit, X-ray control circuit, normal readout circuit, non-destructive readout circuit, projection data generation circuit, estimation circuit, normalization circuit, correction circuit, image generation circuit, and display control circuit, respectively, and may be implemented as individual hardware circuits. The above description of each function performed by the processing circuit 44 is the same in the following embodiments and modifications.

[0031] Furthermore, although the console device 40 is described as performing multiple functions on a single console, it is also possible for multiple functions to be performed by separate devices. For example, the functions of the processing circuit 44 may be distributed and installed on different devices.

[0032] In the above description, the term "processor" refers to circuits such as CPUs (central processing units), GPUs (Graphics Processing Units), Application Specific Integrated Circuits (ASICs), programmable logic devices (e.g., Simple Programmable Logic Devices (SPLDs)), Complex Programmable Logic Devices (CPLDs), and Field Programmable Gate Arrays (FPGAs)). When the processor is a CPU, for example, it performs its functions by reading and executing programs stored in memory circuits. On the other hand, when the processor is an ASIC, for example, instead of storing programs in memory circuits, the functions are directly incorporated into the processor's circuitry as logic circuits. In this embodiment, each processor is not limited to being configured as a single circuit; multiple independent circuits may be combined to form a single processor and perform its functions. Furthermore, multiple components shown in Figure 1 may be integrated into a single processor to perform its functions. The above description of "processor" is the same in the following embodiments and modifications.

[0033] Furthermore, a device comprising a memory 41, a display 42, an input interface 43, and the projection data acquisition function 446, estimation function 447, normalization function 448, correction function 449, image generation function 450, and display control function 451 of the processing circuit 44 may also be called a medical image processing device. Therefore, the explanation of the memory 41, the display 42, the input interface 43, and the projection data acquisition function 446, estimation function 447, normalization function 448, correction function 449, image generation function 450, and display control function 451 of the processing circuit 44 also serves as an explanation of the medical image processing device. In addition, a medical image processing device comprising the memory 41, the display 42, the input interface 43, and the projection data acquisition function 446, estimation function 447, normalization function 448, correction function 449, image generation function 450, and display control function 451 of the processing circuit 44 may be provided as a separate device capable of communicating with the X-ray diagnostic device 1.

[0034] The processing circuit 44 controls each of the multiple components of the X-ray diagnostic apparatus 1 based on input operations received from the operator via the input interface 43, using the system control function 441. For example, the processing circuit 44 controls various components of the imaging apparatus 10 according to the imaging conditions.

[0035] The processing circuit 44 controls the C-arm drive unit 142 and the bed drive unit 32 based on information regarding the driving of the C-arm 14 and the tabletop 33, for example, input from the input interface 43, using the drive control function 442. The processing circuit 44 that implements the drive control function 442 is an example of a drive control unit.

[0036] The processing circuit 44, using the X-ray control function 443, reads information from, for example, the system control function 441 and controls X-ray conditions such as tube current, tube voltage, focal spot size, irradiation time, and pulse width in the high-voltage generator 11. The processing circuit 44 that implements the X-ray control function 443 is an example of an X-ray control unit.

[0037] The processing circuit 44, through its normal readout function 444, causes the X-ray detector 13 to perform a normal readout (destructive readout) of the signal accumulated in the X-ray detection element after the end of X-ray exposure. The normal readout is performed after the end of X-ray exposure, that is, between X-ray pulses. The processing circuit 44 that implements the normal readout function 444 is an example of a second readout unit. The second readout unit may also be called a normal readout unit and a destructive readout unit.

[0038] The processing circuit 44, using a non-destructive readout function 445, causes the X-ray detector 13 to non-destructively read out the signal accumulated in the X-ray detection element before the end of X-ray exposure. Non-destructive readout is performed before the end of X-ray exposure, that is, during the irradiation of a single X-ray pulse. Furthermore, non-destructive readout is performed at a timing that does not cause saturation, depending on the type and performance of the X-ray detector 13. For example, X-ray conditions and readout timing are set so that saturation does not occur even when there is no subject P. Such X-ray conditions and readout timing can be estimated based on the image level of the flood-acquired image. The processing circuit 44 that realizes the non-destructive readout function 445 is an example of a first readout unit. The first readout unit may also be called a non-destructive readout unit.

[0039] The processing circuit 44 acquires projection data generated based on detection data read from the X-ray detector 13 using the projection data acquisition function 446. At this time, the processing circuit 44 acquires projection data (hereinafter referred to as the normal read image) generated using detection data destructively read by the normal read function 444 from the aforementioned projection data generation circuit, and acquires projection data (hereinafter referred to as the non-destructive read image) generated using detection data non-destructively read by the non-destructive read function 445 from the aforementioned projection data generation circuit. The non-destructive read image is an example of the first projection data, and the normal read image is an example of the second projection data. Furthermore, the processing circuit 44 that implements the projection data acquisition function 446 is an example of the acquisition unit.

[0040] The processing circuit 44 uses the estimation function 447 to estimate areas where saturation occurs (hereinafter referred to as saturation areas) based on the normal readout image generated by the projection data acquisition function 446. Saturation is a phenomenon in which the detection value of the X-ray detector 13 saturates when X-rays exceeding the upper limit of the X-ray dose detectable by the X-ray detector 13 are incident on the X-ray detector 13. In saturation areas, even when X-rays exceeding the upper limit are incident, values ​​near the upper limit of the X-ray dose are detected as the detection value, and the correct value is not detected. One method for estimating saturation areas is to determine that saturation occurs in areas of the normal readout image where the signal value exceeds a predetermined threshold. As a predetermined threshold, for example, a value near the upper limit of the X-ray dose detectable by the X-ray detector 13 is used. The processing circuit 44 also uses the estimation function 447 to estimate areas where saturation does not occur (hereinafter referred to as non-saturation areas) based on the normal readout image generated by the projection data acquisition function 446. The processing circuit 44 that implements the estimation function 447 is an example of an estimation unit.

[0041] The processing circuit 44, using the normalization function 448, performs normalization processing on the normal readout image and the non-destructive readout image generated by the projection data acquisition function 446. In the normalization processing, the processing circuit 44 calculates the X-ray attenuation rate A of the normal readout image and the X-ray attenuation rate A' of the non-destructive readout image, and generates normal normalized data including the X-ray attenuation rate A of the normal readout image and non-destructive normalized data including the X-ray attenuation rate A' of the non-destructive readout image. The X-ray attenuation rate is calculated using the ratio of the X-ray intensity transmitted through the object to the X-ray intensity when there is no object. The calculated X-ray attenuation rate is used in calculations during the reconstruction process.

[0042] The X-ray attenuation rate A of a normal readout image is calculated using equation (1). As shown in equation (1), the X-ray attenuation rate A of a normal readout image is calculated using the X-ray intensity I of the normal readout image, the X-ray intensity I0 of the flood image, and the coefficient f. The X-ray intensity I of the normal readout image corresponds to the X-ray intensity transmitted through the subject, and the X-ray intensity I0 of the flood image corresponds to the X-ray intensity when there is no subject. A flood image is an image taken without a subject. Flood images may also be called air-collected images.

[0043]

number

[0044] The coefficient f is a coefficient used to minimize the discrepancy between the X-ray conditions of the normal readout image and the Flood image. The coefficient f is calculated, for example, using equation (2).

[0045]

number

[0046] Here, "kVp" is the tube voltage, "mA" is the tube current, and "sec" is the X-ray exposure time. If the value in parentheses is "I", it indicates the X-ray conditions used when acquiring a normal readout image. If the value in parentheses is "I0", it indicates the X-ray conditions used when acquiring a flood image.

[0047] It is assumed that the X-ray conditions differ between the X-ray imaging used to generate the flood image and the X-ray imaging used to generate the normal readout image. Therefore, by multiplying the ratio of the X-ray intensity I0 of the flood image to the X-ray intensity I of the normal readout image by a coefficient f, the difference in X-ray conditions can be suppressed.

[0048] The X-ray attenuation rate A' of the non-destructive readout image is calculated using equation (3). As shown in equation (3), the X-ray attenuation rate A' of the non-destructive readout image is calculated using the X-ray intensity I' of the non-destructive readout image, the X-ray intensity I0 of the flood image, and the coefficient f'. The X-ray intensity I' of the non-destructive readout image corresponds to the X-ray intensity transmitted through the object, and the X-ray intensity I0 of the flood image corresponds to the X-ray intensity when there is no object.

[0049]

number

[0050] The coefficient f' is a coefficient used to adjust the difference in X-ray conditions between the non-destructive readout image and the flood image, and to align the image levels of the normal readout image and the non-destructive readout image. The coefficient f' is calculated, for example, using equation (4). To match the image intensity of the normal readout image with the image level of the non-destructive readout image, the coefficient f' is obtained by multiplying the coefficient f used when calculating the X-ray attenuation rate of the normal readout image by the ratio of the image level of the normal readout image to the image level of the non-destructive readout image. For example, the average value of the X-ray intensity in the non-saturation region of the normal readout image and the non-destructive readout image can be used as the image levels of the normal readout image and the non-destructive readout image.

[0051]

number

[0052] For example, if the X-ray intensity I' of the non-destructive readout image is approximately half the X-ray intensity I of the normal readout image, then I' ≈ (1 / 2)·I. In this case, the image level of the non-destructive readout image is approximately half the image level of the normal readout image, so the coefficient f' becomes approximately twice the value of the coefficient f, as shown in equation (5).

[0053]

number

[0054] Furthermore, the X-ray attenuation A' of the non-destructive readout image is approximately the same as the X-ray attenuation A of the normal readout image, as shown in equation (6).

[0055]

number

[0056] Thus, while the X-ray intensity in non-destructive readout images is lower than that in normally readout images, by multiplying the ratio of the normally readout image to the non-destructive readout image as a coefficient during the normalization process for non-destructive readout images, it is possible to calculate non-destructive normalized data with consistent image levels with normally normalized data.

[0057] Furthermore, when using the coefficient f' to align the image levels of the normally readout image and the non-destructive readout image, the ratio of the X-ray accumulation time during normal readout to the X-ray accumulation time during non-destructive readout can be used instead of the ratio of the image levels of the normally readout image to the image levels of the non-destructive readout image. However, the X-ray accumulation time is a value stored in the system, and errors may occur compared to the actual time the X-rays were accumulated. Therefore, if the ratio of the X-ray accumulation times is used to suppress the discrepancy in image levels between the normally readout image and the non-destructive readout image, a discrepancy may occur between the normalization results of the normally readout image and the normalization results of the non-destructive readout image.

[0058] On the other hand, as shown in equation (4), if the ratio of the image level of the normal readout image to the image level of the non-destructive readout image is used to suppress the discrepancy in image levels between the normal readout image and the non-destructive readout image, the value actually acquired by the X-ray detector 13 is used, so the discrepancy in image levels between the normal readout image and the non-destructive readout image can be accurately matched. Furthermore, if there is no error between the readout time and the actual image level, it is also effective to use the ratio of the X-ray accumulation time during normal readout to the X-ray accumulation time during non-destructive readout.

[0059] The processing circuit 44 performs saturation correction on the normal readout image using the correction function 449. In saturation correction, the processing circuit 44 replaces the X-ray attenuation rate A of the saturation region in the normal normalized data with the X-ray attenuation rate A' of the saturation region in the non-destructive normalized data that does not contain saturation, thereby generating corrected data (hereinafter referred to as the saturation-corrected image) that combines the saturation region in the normal normalized data and the non-saturation region in the non-destructive normalized data. The saturation-corrected image is composed of the X-ray attenuation rate that does not contain saturation. Since the image levels of the non-destructive normalized data are aligned with those of the normal normalized data by using the coefficient f' in the normalization process, the saturation-corrected image has the same image levels as the normal normalized data and the non-destructive normalized data. After performing saturation correction, processing such as scattered radiation correction and beam quality hardening may be performed on the saturation-corrected image. In this embodiment, the processing circuit 44 that implements the normalization function 448 and the correction function 449 corresponds to the correction unit.

[0060] The processing circuit 44, using the image generation function 450, performs reconstruction processing on the saturation-corrected image generated by the correction function 449 to generate a saturation-corrected X-ray image. The saturation-corrected X-ray image is, for example, volume data. The processing circuit 44 may also perform various synthesis and subtraction processes on the generated X-ray image. The processing circuit 44 that implements the image generation function 450 is an example of an image generation unit and a reconstruction unit.

[0061] In the reconstruction process, the pixel value at each position on the X-ray image is calculated using equation (7) and the X-ray attenuation rate in the corrected image generated by the correction function 449. Here, "μ" is the X-ray attenuation coefficient, and "t" is the thickness of the material through which the X-rays pass. "AttenuationRate" is the X-ray attenuation rate. The tomographic image obtained by the X-ray diagnostic device 1 can also be called the distribution of the X-ray attenuation coefficient μ.

[0062]

number

[0063] The processing circuit 44 reads signals from the system control function 441 via the display control function 451, acquires a desired X-ray image from the memory 41, and displays it on the display 42. The processing circuit 44 that implements the display control function 451 is an example of a display control unit.

[0064] Next, the operation of the X-ray diagnostic apparatus 1 according to this embodiment will be described. Note that the processing procedure described below is merely an example, and each process may be modified as much as possible. Furthermore, depending on the embodiment, steps in the processing procedure described below can be omitted, replaced, or added as appropriate.

[0065] Figure 2 is a flowchart showing an example of the procedure for image generation processing performed by the processing circuit 44 according to this embodiment. Image generation processing is the process of generating an X-ray image of a subject P by pulse-irradiating the subject P with X-rays and detecting the X-rays that have passed through the subject P. Furthermore, image generation processing is the process of performing saturation correction on a normal readout image using a non-destructive readout image to generate a saturation correction. Here, the process of generating an X-ray image for exposure to a single X-ray pulse will be explained as an example. Image generation processing is started after the normal readout for the exposure to the previous X-ray pulse is completed, the accumulation of charge signals in the X-ray detector 13 is reset, and the signal in the X-ray detection element is empty.

[0066] Figure 3 is a diagram illustrating the timing of signal readout performed by the image generation process. The horizontal axis in Figure 3 represents time. Figure 3 shows the process from resetting the charge signal accumulation in the X-ray detector 13, to irradiating with one X-ray pulse, and then resetting the signal accumulated by the X-ray pulse after the exposure to the X-ray pulse has finished. Here, the time when normal readout is performed (hereinafter referred to as the normal readout time) is denoted as t1, and the time when non-destructive readout is performed (hereinafter referred to as the non-destructive readout time) is denoted as t2. Figure 4 is a diagram illustrating the processing flow until a saturation-corrected image is generated by the image generation process.

[0067] (Image generation process) (Step S101) The processing circuit 44 performs X-ray imaging using the imaging device 10 through the system control function 441, the drive control function 442, and the X-ray control function 443. At this time, the processing circuit 44 starts the irradiation of X-ray pulses from the X-ray generator 12 at the irradiation start time ts. The irradiated X-rays continue until the irradiation end time te. As a result, X-rays are irradiated onto the subject P during the time A from the irradiation start time ts to the irradiation end time te. Time A is the X-ray storage time during normal readout.

[0068] (Step S102) Next, the processing circuit 44, using the non-destructive readout function 445, non-destructively reads out the signal accumulated in the X-ray detection element from the X-ray detector 13 at the non-destructive readout time t2. At this time, the signal accumulated during time B from the irradiation start time ts to the non-destructive readout time t2 is read out. Time B is the X-ray accumulation time at the time of non-destructive readout. Since the signal accumulated in the X-ray detection element during time B is read out non-destructively, the signal accumulated in the X-ray detection element is retained even after the non-destructive readout without becoming empty. The non-destructive readout time t2 is set to a time between the irradiation start time ts and the irradiation end time te. Therefore, the signal accumulated in the X-ray detection element is read out from the X-ray detector 13 before the end of X-ray exposure, that is, during the irradiation of one X-ray pulse. The non-destructive readout time t2 is preset to a time that does not cause saturation, depending on the type and performance of the X-ray detector 13.

[0069] (Step S103) Next, the processing circuit 44 uses the normal readout function 444 to normally read out the signal accumulated in the X-ray detection element from the X-ray detector 13 at the normal readout time t1. At this time, the signal accumulated during time A from the irradiation start time ts to the irradiation end time te is read out. Since the signal accumulated in the X-ray detection element is read out in a destructive manner, the signal accumulated in the X-ray detection element becomes empty. The normal readout time t1 is set to a time later than the irradiation end time te. Therefore, after the end of X-ray exposure, that is, after irradiation with one X-ray pulse, the signal accumulated in the X-ray detection element is read out from the X-ray detector 13. In addition, saturation may occur in the signal read out by the normal readout function 444.

[0070] (Step S104) Next, the processing circuit 44 executes the projection data acquisition function 446. In the projection data acquisition function 446, the processing circuit 44 acquires a normal read image generated from the projection data generation circuit based on the detection data acquired by normal read in the processing of step S103, and acquires a non-destructive read image generated from the projection data generation circuit based on the detection data acquired by non-destructive read in the processing of step S102. The normal read image includes saturation. On the other hand, the non-destructive read image does not include saturation. The generated normal read image and non-destructive read image are stored in, for example, memory 41.

[0071] (Step S105) Next, the processing circuit 44 uses the estimation function 447 to estimate the saturated region and the non-saturated region based on the normal readout image acquired in the processing of step S104.

[0072] (Step S106) Next, the processing circuit 44 uses the normalization function 448 to perform normalization processing on both the normally read image and the non-destructive read image, generating normally normalized data and non-destructive normalized data. At this time, the processing circuit 44 performs the normalization processing so that the image levels of the normally read image and the non-destructive read image are aligned.

[0073] (Step S107) Next, the processing circuit 44 performs saturation correction on the normal readout image using the correction function 449. In saturation correction, the processing circuit 44 replaces the saturation region of the normal readout image with the saturation region of the non-destructive readout image. In other words, the processing circuit 44 generates a corrected image by combining the X-ray attenuation rate of the normally normalized data in the saturation region and the X-ray attenuation rate of the non-destructive normalized data in the non-saturation region.

[0074] (Step S108) Next, the processing circuit 44 performs reconstruction processing using the image generation function 450. In the reconstruction process, the processing circuit 44 generates an X-ray image by performing reconstruction processing on the corrected image generated in step S107. The X-ray image is, for example, volume data. The generated X-ray image does not contain saturation because the pixel values ​​of the saturation region are calculated using the non-destructive readout image. The generated X-ray image is stored in, for example, the memory 41.

[0075] (Step S109) The processing circuit 44 generates tomographic data and 3D image data based on the X-ray image using the image generation function 450, for display on the display 42. The processing circuit 44 stores the generated tomographic data and 3D image data in the memory 41. Then, the processing circuit 44 executes the display control function 451. In the display control function 451, the processing circuit 44 displays the tomographic data and 3D image data as an X-ray image on the display 42.

[0076] The processing circuit 44 repeats the processes from step S101 to step S109 each time an X-ray pulse is irradiated, thereby continuously generating a saturation-corrected X-ray image, and displays the generated X-ray image on the display 42.

[0077] The following describes the effects of the X-ray diagnostic device 1, which is a medical imaging diagnostic device according to this embodiment.

[0078] The X-ray diagnostic apparatus 1 of this embodiment can, before the end of X-ray exposure, have the signal accumulated in the X-ray detection element read out non-destructively by the X-ray detector 13, and after the end of X-ray exposure, have the signal read out destructively by the X-ray detector 13, acquire a non-destructive readout image generated based on the signal read out by non-destructive readout, acquire a normal readout image generated based on the signal read out by destructive readout, estimate the saturation region where saturation is occurring based on the normal readout image, and replace the signal of the saturation region in the normal readout image with the signal of the saturation region in the non-destructive readout image. Here, the non-destructive readout image is an example of first projection data, and the normal readout image is an example of second projection data.

[0079] With the above configuration, the X-ray diagnostic apparatus 1 according to this embodiment can perform accurate saturation correction by using an X-ray detector 13 with a non-destructive readout function to acquire a non-destructive readout image that does not cause saturation, and by using the acquired non-destructive readout image as a correction image to correct the saturated area of ​​the normal readout image. In other words, by detecting the saturated area of ​​the normal readout image and replacing that area with a non-destructive readout image without saturation, it becomes possible to perform reconstruction processing on data without saturation, and a reconstructed image without artifacts caused by saturation can be generated. By generating a reconstructed image without artifacts, the user can easily perform a diagnosis.

[0080] Furthermore, the X-ray diagnostic apparatus 1, which is a medical image diagnostic apparatus according to this embodiment, can replace the signal of a normally readout image while ensuring that the image level of the non-destructive readout image and the image level of the normally readout image are aligned.

[0081] Specifically, the image levels of the non-destructive readout image and the conventional readout image can be aligned by converting the X-ray attenuation rate of the non-destructive readout image. For example, as shown in equations (3) and (4), the image levels of the non-destructive readout image and the conventional readout image can be aligned using a coefficient f' that includes the ratio of the image levels of the non-destructive readout image and the conventional readout image.

[0082] According to the above configuration, by matching the image level of the non-destructive readout image with the image level of the normal readout image, it is possible to generate an X-ray image that is free from artifacts caused by saturation and in which the difference in image level between the saturated and non-saturated regions is suppressed.

[0083] Furthermore, by using the ratio of the image level of the normally readout image to the image level of the non-destructive readout image, the values ​​actually acquired by the X-ray detector 13 are used, thus suppressing the discrepancy in the normalization processing results between the normally readout image and the non-destructive readout image.

[0084] (First variation) The first modification will now be described. This modification is a modification of the configuration of the embodiment as follows. The same configuration, operation, and effects as in the embodiment will not be described.

[0085] In the above-described embodiment, when calculating the X-ray attenuation rate A' of the non-destructive readout image using the normalization function 448, a coefficient was used to match the image levels of the normal readout image and the non-destructive readout image. Then, saturation correction was performed using the normalization processing results of the normal readout image and the non-destructive readout image. On the other hand, in this modified example, saturation correction is performed using the normal readout image and the non-destructive readout image before performing the normalization processing.

[0086] The processing circuit 44 performs saturation correction on the normal readout image using the saturation region of the non-destructive readout image via the correction function 449. In saturation correction, the processing circuit 44 first performs a correction to match the image levels of the normal readout image and the non-destructive readout image, thereby generating a non-destructive readout image corrected to the same image level as the normal readout image (hereinafter referred to as the corrected non-destructive readout image). One method for matching the image levels of the normal readout image and the non-destructive readout image is to perform a correction by multiplying the non-destructive readout image by the ratio of the image level of the normal readout image to the image level of the non-destructive readout image. In this case, the image levels of the normal readout image and the non-destructive readout image are matched by converting the image level of the non-destructive readout image. Alternatively, instead of the ratio of the image level of the normal readout image to the image level of the non-destructive readout image, the non-destructive readout image may be multiplied by the ratio of the X-ray accumulation time during normal readout to the X-ray accumulation time during non-destructive readout.

[0087] The processing circuit 44, using the correction function 449, uses the corrected image of the non-destructive readout image and the normal readout image to replace the signals of the saturation region in the normal readout image with the signals of the saturation region in the non-destructive normalized data that does not contain saturation. This generates a composite image that combines the saturation region in the normal readout image and the non-saturation region in the non-destructive readout image. The composite image consists of signals that do not contain saturation. In this modified example, the processing circuit 44 that implements the correction function 449 is an example of a correction unit.

[0088] The processing circuit 44 performs normalization processing on the composite image generated by the correction function 449 using the normalization function 448. In the normalization processing, the processing circuit 44 calculates the X-ray attenuation rate of the composite image and generates normalized data including the X-ray attenuation rate of the composite image. The X-ray attenuation rate of the composite image is calculated using the ratio of the X-ray intensity of the composite image to the X-ray intensity of the Flood image and a coefficient to suppress the difference in X-ray conditions between the composite readout image and the Flood image, similar to the calculation formula (1) for the X-ray attenuation rate A of the normal readout image described above. As the X-ray conditions of the composite readout image, for example, the X-ray conditions during normal readout can be used.

[0089] The processing circuit 44 uses the image generation function 450 to perform the aforementioned reconstruction process on the composite image generated by the normalization function 448, thereby generating a saturation-corrected image.

[0090] Figure 5 is a flowchart showing an example of the image generation process performed by the processing circuit 44 according to this modified example. The processes in steps S201-S205 and S209 are the same as those in steps S101-S105 and S109 in Figure 2, respectively, so their explanation is omitted. Figure 6 is a diagram illustrating the process flow until a saturation-corrected image is generated by the image generation process.

[0091] (Image generation process) (Step S206) The processing circuit 44 performs saturation correction on the normal readout image using the correction function 449. In saturation correction, the processing circuit 44 first generates a corrected image of the non-destructive readout image by multiplying the non-destructive readout image by the ratio of the image level of the normal readout image to the image level of the non-destructive readout image. Next, the processing circuit 44 generates a composite image by replacing the saturated region of the normal readout image with the saturated region of the non-destructive readout image, thereby combining the saturated region of the normal readout image and the non-saturated region of the non-destructive readout image.

[0092] (Step S207) Next, the processing circuit 44 uses the normalization function 448 to perform normalization processing on the composite image generated in step S206, thereby generating normalized data.

[0093] (Step S208) Next, the processing circuit 44 generates an X-ray image by performing a reconstruction process on the normalized data generated in step S207 using the image generation function 450. The generated X-ray image does not contain saturation because the pixel values ​​of the saturation region are calculated using the non-destructive readout image. The generated X-ray image is stored in, for example, memory 41.

[0094] The effects of the X-ray diagnostic device 1, which is a medical imaging diagnostic device related to this modified example, will be explained below.

[0095] In this modified X-ray diagnostic apparatus 1, the image level of the non-destructive readout image can be matched with the image level of the normal readout image by converting the image level of the non-destructive readout image. Here, the non-destructive readout image is an example of the first projection data, and the normal readout image is an example of the second projection data.

[0096] In the above-described embodiment, a coefficient was used to match the image level of the normally read image in the normalization process for the non-destructive read image. Therefore, in the normalization process, it was necessary to perform normalization using separate formulas for the normally read image and the non-destructive read image. On the other hand, in this modified example, by performing saturation correction, which includes correction to match the image levels of the normally read image and the non-destructive read image, on the non-destructive read image before the normalization process is executed, the normalization process can be performed without using separate formulas for the normally read image and the non-destructive read image.

[0097] (Second variation) Furthermore, when calculating the X-ray attenuation rate A' of the non-destructive readout image during the normalization process, in order to align the image levels of the normal readout image and the non-destructive readout image, the X-ray intensity I0 of the flood image may be used instead of the X-ray intensity I0 of the flood image, which was acquired without a subject and generated by non-destructive readout. In this case, by using the X-ray intensity of the flood image generated by non-destructive readout, the discrepancy in image levels between the normal readout image and the non-destructive readout image is suppressed, and the same coefficient f as in the normalization process for the normal readout image can be used instead of the coefficient f'.

[0098] (Third variation) A third modification will now be described. This modification is a modification of the configuration of the embodiment as follows. The same configuration, operation, and effects as in the embodiment will not be described. In the above-described embodiment, the same coefficient f' was used at all positions in the normalization process for the non-destructive readout image. During non-destructive readout, readout is performed sequentially from multiple X-ray detection elements during X-ray irradiation, so a difference in X-ray accumulation time may occur depending on the X-ray detection element. As a result, in the non-destructive readout image, unevenness in image level occurs at each pixel due to the difference in X-ray accumulation time. In this modification, the non-destructive readout image is divided into multiple regions, and a different coefficient is used for each of the divided regions to perform the normalization process.

[0099] The processing circuit 44, using the normalization function 448, first divides the non-destructive readout image into multiple regions with different readout timings (hereinafter referred to as readout regions). Next, the processing circuit 44 performs normalization processing using a different coefficient f' for each of the divided readout regions. For example, in the above-mentioned formula (4) for calculating the coefficient f', the average value of the image level for each readout region is used as the non-destructive readout image level. Then, normalization processing is performed for each of the multiple readout regions using a different value as the non-destructive readout image level. As a result, the image level of the non-destructive readout image in each readout region is aligned with the image level of the normal readout image.

[0100] In this modified example, by performing normalization processing for each of the multiple read regions with different read timings, it is possible to suppress image level inconsistencies caused by differences in read timing when acquiring non-destructive read images.

[0101] (Fourth variation) A fourth modification will now be described. This modification is a modification of the configuration of the embodiment as follows. The same configuration, operation, and effects as in the embodiment will not be described.

[0102] In this modified example, the X-ray detector 13 is a detector capable of performing multiple non-destructive readouts during a single X-ray exposure.

[0103] The processing circuit 44, using the non-destructive readout function 445, performs a preset number of non-destructive readouts during a single X-ray pulse irradiation. The processing circuit 44 acquires a non-destructive readout image generated using the detection data detected by the multiple non-destructive readouts. The method for generating the non-destructive readout image will be described later.

[0104] Figure 7 is a diagram illustrating the timing of signal readout performed by the image generation process in this modified example. The horizontal axis in Figure 7 represents time. Figure 7 shows the process from resetting the charge signal accumulation in the X-ray detector 13, irradiating with one X-ray pulse, and resetting the signal accumulated by the X-ray pulse after the exposure to the X-ray pulse has finished.

[0105] This section explains the case where non-destructive readout is performed at a first readout time t2 and a second readout time t3 during a single X-ray pulse irradiation. The second readout time t3 is later than the first readout time t2. The first readout time t2 and the second readout time t3 are preset times relative to the irradiation start time ts.

[0106] When non-destructive readout is performed at the first readout time t2, the signal accumulated during the time B from the irradiation start time ts to the first readout time t2 is read out. At this time, since the signal accumulated in the X-ray detection element is read out non-destructively, the signal accumulated in the X-ray detection element is retained even after the non-destructive readout, without becoming empty.

[0107] When non-destructive readout is performed at the second readout time t3, the signal accumulated during the time C from the irradiation start time ts to the second readout time t3 is read out. At this time, since the signal accumulated in the X-ray detection element is read out non-destructively, the signal accumulated in the X-ray detection element is retained even after the non-destructive readout, without becoming empty.

[0108] Furthermore, the first readout time t2 and the second readout time t3 are set to the boundary times obtained by dividing the time A, from the start time ts of X-ray pulse irradiation to the end time te, into three equal parts. That is, the time B from the start time ts to the first readout time t2, the time D from the first readout time t2 to the second readout time t3, and the time AC from the second readout time t3 to the end time te are approximately the same. Also, the center time between the first readout time t2 and the second readout time t3 coincides with the center time between the start time ts of X-ray exposure and the normal readout time t1. That is, the first readout time t2 and the second readout time t3 are set to be the same time away from the center time tm of X-ray exposure. Note that it is sufficient for the first readout time t2 and the second readout time t3 to be set to be the same time away from the center time tm of X-ray exposure.

[0109] The processing circuit 44 acquires a non-destructive readout image generated using the data obtained by subtracting the detection data read at the first readout time t2 from the detection data read at the second readout time t3. The non-destructive readout image is projection data that includes signals accumulated during the time D from the first readout time t2 to the second readout time t3.

[0110] In the above-described embodiment, a shift in the position of the object may occur between the start and end of X-ray pulse irradiation due to timing differences in the readout or vibration of the X-ray detector 13 during rotational acquisition. In this case, depending on the timing of non-destructive readout, the center position of the object in the non-destructive readout image may differ from the center position of the object in the normal readout image.

[0111] On the other hand, in this modified example, by performing multiple non-destructive readouts set at timings equal to the same time away from the center time tm of X-ray exposure, and acquiring a non-destructive readout image generated using the difference in the readout detection data, it is possible to obtain a non-destructive image corresponding to the X-rays accumulated at a timing that coincides with the center timing of the X-ray irradiation time. This suppresses the shift in the central position of the object in the non-destructive image compared to the normal readout image.

[0112] (Fifth variation) A fifth modification will now be described. This modification is a modification of the configuration of the embodiment as follows. The same configuration, operation, and effects as in the embodiment will not be described.

[0113] In this modified example, the processing circuit 44, using the correction function 449, replaces the X-ray attenuation rate in the region near the boundary between the saturation region and the non-saturation region (hereinafter referred to as the boundary region) in the saturation-corrected image obtained by replacing the saturation region in the normally normalized data with non-destructive normalized data, with a value obtained by mixing the X-ray attenuation rate A of the normally normalized data and the X-ray attenuation rate A' of the non-destructive normalized data. For example, the X-ray attenuation rate in the boundary region is replaced with a value obtained by combining the X-ray attenuation rate A of the normally normalized data and the X-ray attenuation rate A' of the non-destructive normalized data in a predetermined ratio. For example, if the area inside the boundary is the non-saturation region and the area outside the boundary is the saturation region, the X-ray attenuation rate at a position slightly inside the boundary is set to the value obtained by using the X-ray attenuation rate A of the normally normalized data as is, and as you move towards the outside of the boundary, the ratio of mixing the X-ray attenuation rate A' of the non-destructive normalized data with the X-ray attenuation rate A of the normally normalized data increases.

[0114] In the above-described embodiment, discontinuities in signal values ​​at the boundary between saturation and non-saturation regions may occur due to timing discrepancies in readout or vibrations of the X-ray detector 13 during rotational acquisition. On the other hand, in this modified example, when replacing the saturation region of the normally readout image with the saturation region of the non-destructive readout image, a boundary region is provided in which the X-ray attenuation rate A of the normally normalized data and the X-ray attenuation rate A' of the non-destructive normalized data are mixed in a predetermined ratio, thereby generating a saturation-corrected image with a smooth boundary.

[0115] (Sixth variation) Alternatively, the above-described normal readout and non-destructive readout may be performed each time the C-arm 14 rotates by a predetermined angle, and the above-described saturation correction may be performed using the normal readout image and non-destructive readout image read out at each predetermined rotation angle to generate an X-ray image. In this case, for example, a normalization process is performed on multiple non-destructive readout images generated at each predetermined rotation angle using different coefficients f', so that the image levels of the non-destructive readout image and the normal readout image are aligned.

[0116] (Other embodiments) The functions of the embodiments described above may be mounted in a device separate from the X-ray diagnostic apparatus 1. For example, it may be implemented as a medical image processing device equipped with a processing circuit that acquires detection data output from the X-ray detector 13 of the X-ray diagnostic apparatus 1 and executes projection data acquisition function 446, estimation function 447, normalization function 448, correction function 449, image generation function 450, and display control function 451 on the acquired detection data. In this case as well, the same effects as the embodiments and modifications described above can be obtained.

[0117] According to at least one embodiment described above, it is possible to generate medical images with reduced artifacts caused by saturation.

[0118] While several embodiments have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be implemented in a variety of other forms, and various omissions, substitutions, modifications, and combinations of embodiments are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0119] 1...X-ray diagnostic equipment 10… Imaging device 11…High-voltage generator 12...X-ray generating section 13…X-ray detector 14…C-arm 142...C-arm drive unit 30... Bed equipment 31…Base 32... Bed drive mechanism 33... Tabletop 34…Support frame 40…Console device 41…Memory 42…Display 43…Input Interface 44… Processing circuit 441... System control function 442…Drive control function 443...X-ray control function 444...Normal read function 445...Non-destructive reading function 446...Projection data acquisition function 447…Estimated function 448... Normalization function 449... Correction function 450...Image generation function 451…Display control function ts…Irradiation start time te... Irradiation end time t1...Normal read time t2, t3... Non-destructive readout time tm…Center time

Claims

1. A first readout unit that non-destructively reads out the signal accumulated in the X-ray detection element to the X-ray detector before the end of X-ray exposure, A second readout unit causes the X-ray detector to read out the signal after the X-ray exposure is complete, An acquisition unit that acquires first projection data generated based on a signal read by non-destructive readout, and second projection data generated based on a signal read by destructive readout, An estimation unit that estimates the saturation region where saturation is occurring based on the second projection data, A correction unit that replaces the signal of the saturation region in the second projection data with the signal of the saturation region in the first projection data, An X-ray diagnostic device equipped with [specific features / features].

2. The correction unit replaces the signal of the second projection data while aligning the image levels of the first projection data and the second projection data. The X-ray diagnostic apparatus according to claim 1.

3. The correction unit aligns the image level of the first projection data with the image level of the second projection data by converting the X-ray attenuation rate of the first projection data. The X-ray diagnostic apparatus according to claim 2.

4. The correction unit aligns the image level of the first projection data with the image level of the second projection data by calculating the X-ray attenuation rate of the second projection data using the air-collected image generated by non-destructive readout in the absence of a subject. The X-ray diagnostic apparatus according to claim 2.

5. The correction unit aligns the image level of the first projection data with the image level of the second projection data by converting the image level of the first projection data. The X-ray diagnostic apparatus according to claim 2.

6. The correction unit uses the ratio of the image level of the first projection data to the image level of the second projection data to align the image levels of the first projection data and the second projection data. The X-ray diagnostic apparatus according to any one of claims 2 to 5.

7. The correction unit uses the ratio of the X-ray accumulation time when reading the first projection data to the X-ray accumulation time when reading the second projection data to align the image level of the first projection data with the image level of the second projection data. The X-ray diagnostic apparatus according to any one of claims 2 to 5.

8. The correction unit divides the first projection data into multiple regions with different reading timings, and aligns the image level of the first projection data with the image level of the second projection data for each of the multiple regions. The X-ray diagnostic apparatus according to any one of claims 2 to 7.

9. The first reading unit performs the non-destructive reading at the first reading time and at the second reading time which is after the first reading time. The center time between the first readout time and the second readout time coincides with the center time between the start time of X-ray exposure and the end time of X-ray exposure. The X-ray diagnostic apparatus according to any one of claims 1 to 8.

10. The estimation unit further estimates non-saturated regions where saturation has not occurred based on the second projection data, The correction unit replaces the signals near the boundary between the saturation region and the non-saturation region in the second projection data with a signal obtained by mixing the signals of the first projection data and the signals of the second projection data. An X-ray diagnostic apparatus according to any one of claims 1 to 9.

11. The correction unit changes the ratio in which the signal of the first projection data and the signal of the second projection data are mixed according to the distance from the boundary. The X-ray diagnostic apparatus according to claim 10.

12. The system further includes a reconstruction processing unit that performs a reconstruction process on the replaced second projection data to generate three-dimensional image data. The X-ray diagnostic apparatus according to any one of claims 1 to 11.

13. The system further includes a support arm for holding the X-ray tube that irradiates X-rays and the X-ray detector, The acquisition unit acquires the first projection data and the second projection data sequentially collected while the X-ray detector rotates around the subject by the support arm. The correction unit replaces the signal of the saturation region in the second projection data with the signal of the saturation region in the first projection data for each rotation angle of the support arm. The X-ray diagnostic apparatus according to any one of claims 1 to 12.

14. An acquisition unit acquires first projection data generated based on a signal read out non-destructively from an X-ray detection element before the end of X-ray exposure, and second projection data generated based on a signal read out destructively from an X-ray detection element after the end of X-ray exposure. An estimation unit that estimates the saturation region where saturation is occurring based on the second projection data, A correction unit that replaces the signal of the saturation region in the second projection data with the signal of the saturation region in the first projection data, A medical image processing device equipped with [a specific feature].

Images