Photon counting ct device

Abstract

Embodiments relate to a photon counting CT apparatus. An optimum energy band is decided according to a photographing mode, a photographing subject site, or a kind of medical equipment. A photon counting CT apparatus of an embodiment includes a photon counting detector, an acquisition unit, and a decision unit. The photon counting detector detects X-ray photons and acquires energy information. The acquisition unit acquires at least one of information about a photographing mode, information about a photographing subject site, and information about a medical equipment. The decision unit decides at least one of a condition about an energy band of data collected by the photon counting detector and a condition about an energy band of data used in reconstruction processing among data collected by the photon counting detector, based on information acquired by the acquisition unit.

Description

[0001] Reference to related applications

[0002] This application enjoys the benefit of priority to Japanese Patent Application No. 2020-165483, filed on September 30, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments disclosed in this specification and accompanying drawings relate to a photon counting CT (Computed Tomography) device. Background Technology

[0004] Traditionally, X-ray CT devices have been used to perform CT imaging using a single tube voltage (kV) and collect data from the pre-set tube voltage and tube current (mA) of the X-ray tube (bulb). For example, an X-ray CT device may use a single tube voltage to collect information from two fixed energy sources. Additionally, X-ray CT devices may sometimes use two tube voltages, such as dual-energy imaging, depending on the clinical purpose. In either the case of using a single tube voltage or using two tube voltages, the tube voltage and tube current are the primary imaging conditions.

[0005] On the other hand, in photon counting CT imaging, X-ray detectors can be used to collect information on multiple arbitrary energies (energy information). Summary of the Invention

[0006] One of the problems to be solved by the embodiments disclosed in this specification and accompanying drawings is determining the optimal energy band based on the imaging mode, the body part being imaged, or the type of medical device. However, the technical problems to be solved by the embodiments disclosed in this specification and accompanying drawings are not limited to the above-mentioned technical problems. Technical problems corresponding to the effects of the various structures shown in the embodiments described below can also be identified as other technical problems.

[0007] The photon-counting CT apparatus of this embodiment includes a photon-counting detector, an acquisition unit, and a decision unit. The photon-counting detector detects X-ray photons and acquires energy information. The acquisition unit acquires at least one of the following: information related to the imaging mode, information related to the area being imaged, and information related to medical equipment. Based on the information acquired by the acquisition unit, the decision unit determines at least one of the following: conditions related to the energy bands of the data collected by the photon-counting detector, and conditions related to the energy bands of the data collected by the photon-counting detector that are used in the reconstruction process.

[0008] Effect

[0009] The photon counting CT device according to the embodiment can determine the optimal energy band based on the imaging mode, the area to be imaged, or the type of medical equipment. Attached Figure Description

[0010] Figure 1 This is a diagram showing a structural example of the X-ray CT apparatus according to the first embodiment.

[0011] Figure 2 This is a diagram used to illustrate the X-ray detector of the first embodiment.

[0012] Figure 3 This diagram illustrates one example of the multiple energy bands that can be used when the X-ray detector of the first embodiment generates digital data.

[0013] Figure 4 This is a diagram illustrating an example of the data structure of the energy table in the first embodiment.

[0014] Figure 5 This is a flowchart illustrating an example of the process of the first band determination process performed by the X-ray CT apparatus of the first embodiment.

[0015] Figure 6 This is a diagram showing an example of the energy band determined in the first embodiment.

[0016] Figure 7 This is a diagram illustrating an example of a surveillance image based on surveillance image data according to the first embodiment.

[0017] Figure 8 This is a diagram illustrating an example of an image based on image data according to the first embodiment.

[0018] Figure 9 This diagram illustrates an example of the process performed in step S103 when the decision function of the first embodiment obtains other various energy bands in step S102.

[0019] Figure 10 This diagram illustrates an example of the process performed in step S103 when the decision function of the first embodiment obtains other various energy bands in step S102.

[0020] Figure 11 This diagram illustrates an example of the process performed in step S103 when the decision function of the first embodiment obtains other various energy bands in step S102.

[0021] Figure 12 This diagram illustrates an example of the process performed in step S103 when the decision function of the first embodiment obtains other various energy bands in step S102.

[0022] Figure 13 This diagram illustrates an example of the process performed in step S103 when the decision function of the first embodiment obtains other various energy bands in step S102.

[0023] Figure 14 This is a diagram illustrating an example of the data structure of the energy table in a variation of the first embodiment.

[0024] Figure 15 This is a flowchart illustrating an example of the second band determination process performed by an X-ray CT apparatus that represents a variation of the first embodiment.

[0025] Figure 16 This is a diagram illustrating an example of the data structure of the energy table in the second embodiment.

[0026] Figure 17 This is a flowchart illustrating an example of the third band determination process performed by the X-ray CT apparatus of the second embodiment.

[0027] Figure 18 This is a flowchart illustrating an example of the fourth band determination process performed by the X-ray CT apparatus of the third embodiment.

[0028] Figure 19 This is a flowchart illustrating an example of the fifth band determination process performed by the X-ray CT apparatus of the third embodiment.

[0029] Figure 20 This is a flowchart illustrating an example of the sixth band determination process performed by the X-ray CT apparatus of the third embodiment.

[0030] Figure 21 This is a flowchart illustrating an example of the reconstruction condition determination process performed by the X-ray CT apparatus of the fourth embodiment.

[0031] Figure 22 This is a diagram illustrating an example of the processing performed by the X-ray CT apparatus of the fifth embodiment.

[0032] Figure 23 This is a diagram illustrating an example of the data structure of the energy table in the sixth embodiment.

[0033] Figure 24 This is a flowchart illustrating an example of the seventh band determination process performed by the X-ray CT apparatus of the sixth embodiment. Detailed Implementation

[0034] Hereinafter, X-ray CT apparatuses according to various embodiments will be described with reference to the accompanying drawings. Furthermore, the content described in one embodiment or one variation is generally applicable to other embodiments or other variations as well.

[0035] (First Implementation)

[0036] Figure 1 This diagram illustrates a structural example of the X-ray CT apparatus 1 according to the first embodiment. The X-ray CT apparatus 1 is a photon-counting CT apparatus capable of performing photon-counting CT. That is, instead of using a conventional integrating (current-mode measurement) detector, the X-ray CT apparatus 1 uses a photon-counting detector to count the photons of X-rays transmitted through the subject P, thereby enabling the reconstruction of X-ray CT image data with a high signal-to-noise ratio (S / N). Figure 1 As shown, the X-ray CT apparatus 1 of the first embodiment includes a stand 10, an examination bed 20, and a control console 30.

[0037] The stage 10 is a device for irradiating a subject P with X-rays and collecting data related to the X-rays transmitted through the subject P. The stage 10 includes an X-ray high-voltage device 11, an X-ray generating device 12, an X-ray detector 13, a data collection circuit 14, a rotating frame 15, and a stage control device 16. Furthermore, in the stage 10, such as... Figure 1 As shown, an orthogonal coordinate system consisting of the X-axis, Y-axis, and Z-axis is defined. That is, the X-axis represents the horizontal direction, the Y-axis represents the vertical direction, and the Z-axis represents the direction of the rotation center axis of the rotating frame 15 when the platform 10 is in a non-tilted state.

[0038] The rotating frame 15 is a ring-shaped frame that supports the X-ray generating device 12 and the X-ray detector 13 in a way that clamps the subject P and is positioned opposite each other. It rotates at high speed on a circular track centered on the subject P by the stage control device 16 described later.

[0039] X-ray generating apparatus 12 is a device that generates X-rays and irradiates the object P with the generated X-rays. X-ray generating apparatus 12 includes an X-ray tube (bulb) 12a, a wedge 12b, and a collimator 12c.

[0040] X-ray tube 12a is a vacuum tube that receives a high voltage supply from X-ray high-voltage device 11 and irradiates thermionic electrons from the cathode (sometimes also called a filament) to the anode (target). As the rotating frame 15 rotates, X-ray tube 12a irradiates the subject P with an X-ray beam. That is, X-ray tube 12a uses the high voltage supplied from X-ray high-voltage device 11 to generate X-rays.

[0041] Furthermore, the X-ray tube 12a generates an X-ray beam that extends with a fan angle and a cone angle. For example, the X-ray tube 12a can be controlled by the X-ray high-voltage device 11 to continuously irradiate X-rays around the entire area of ​​the subject P during full reconstruction, or to continuously irradiate X-rays within a semi-reconstructable irradiation range (180 degrees + fan angle) during semi-reconstruction. Additionally, the X-ray tube 12a can be controlled by the X-ray high-voltage device 11 to intermittently irradiate X-rays (pulsed X-rays) at a predetermined position (tube position). Furthermore, the X-ray high-voltage device 11 can also modulate the intensity of the X-rays irradiated from the X-ray tube 12a. For example, the X-ray high-voltage device 11 can increase the intensity of the X-rays irradiated from the X-ray tube 12a at a specific tube position, and decrease the intensity of the X-rays irradiated from the X-ray tube 12a in areas outside the specific tube position.

[0042] Wedge 12b is an X-ray filter used to adjust the X-ray dose of X-rays irradiated from X-ray tube 12a. Specifically, wedge 12b is a filter that transmits and attenuates the X-rays irradiated from X-ray tube 12a so that the X-rays irradiated from X-ray tube 12a onto the subject P are distributed in a predetermined manner. For example, wedge 12b is a filter obtained by machining aluminum in a manner that achieves a specified target angle and a specified thickness. In addition, wedges are also referred to as wedge filters or bow-tie filters.

[0043] The collimator 12c is made of lead plate or the like and has a slit in a part. For example, the collimator 12c is controlled by the X-ray high voltage device 11 described later, and the irradiation range of the X-rays whose X-ray dose is adjusted by the wedge 12b is reduced by passing through the slit.

[0044] Furthermore, the X-ray source of the X-ray generating device 12 is not limited to the X-ray tube 12a. For example, the X-ray generating device 12 may also consist of a focusing coil that focuses an electron beam generated from an electron gun instead of the X-ray tube 12a, a deflection coil that performs electromagnetic deflection, and a target ring that generates X-rays by colliding with an electron beam that is deflected by a semicircle surrounding the subject P.

[0045] The X-ray high-voltage device 11 comprises circuits such as a transformer and a rectifier, and consists of a high-voltage generating device that generates a high voltage applied to the X-ray tube 12a, and an X-ray control device that controls the output voltage corresponding to the X-rays irradiated by the X-ray tube 12a. The high-voltage generating device can be either a transformer or an inverter. For example, the X-ray high-voltage device 11 adjusts the X-ray dose irradiated on the subject P by adjusting the tube voltage or tube current supplied to the X-ray tube 12a. Furthermore, the X-ray high-voltage device 11 receives control from the processing circuit 37 of the control console 30.

[0046] The stage control device 16 consists of a processing circuit, such as a CPU (Central Processing Unit), and drive mechanisms such as motors and actuators. The stage control device 16 has the function of receiving input signals from the input interface 31 mounted on the control console 30 or the input interface mounted on the stage 10 to control the movement of the stage 10. For example, the stage control device 16 controls the rotation of the rotating frame 15 by receiving input signals, controls the rotation of the X-ray tube 12a and the X-ray detector 13 on a circular track centered on the subject P, controls the tilting of the stage 10, and controls the movement of the examination table 20 and the top plate 22. The stage control device 16 receives control from the processing circuit 37 of the control console 30.

[0047] The X-ray detector 13 is composed of multiple detection elements and is an example of a photon counting detector (photon counting type detector) that outputs a signal corresponding to the counted number of X-ray photons. For example, the X-ray detector 13 is composed of multiple rows of X-ray detection elements (also simply called "sensors" or "detection elements") arranged along an arc in the channel direction centered on the focal point of the X-ray tube 12a. The X-ray detector 13 has a structure consisting of multiple rows of X-ray detection elements arranged in the slicing direction and multiple rows of X-ray detection elements arranged in the channel direction. Each X-ray detection element of the X-ray detector 13 detects the X-rays that have passed through the subject P after being irradiated by the X-ray generating device 12 and outputs an electrical signal (pulse) corresponding to the amount of X-rays. Furthermore, the electrical signal output by each X-ray detection element is also called a detection signal.

[0048] Figure 2 This is a diagram illustrating the X-ray detector 13 of the first embodiment. For example, the X-ray detector 13 is a direct conversion type photon counting detector.

[0049] X-ray detector 13 Figure 2The image shows a photon counting detector with multiple detection units. Each detection unit includes: a detection element (X-ray detection element) 130 for detecting X-ray photons; and an ASIC (Application Specific Integrated Circuit) 134 connected to the detection element 130 for counting the X-ray photons detected by the detection element 130. Furthermore, in Figure 2 In the example, one of the multiple detection units is illustrated.

[0050] Each detection element 130 has a semiconductor 131, a cathode electrode 132, and multiple anode electrodes 133. Here, the semiconductor 131 is a cadmium telluride (CdTe) or zinc cadmium telluride (CZT) semiconductor. Additionally, the anode electrodes 133 correspond to individual detection pixels (also referred to as "pixels"). When X-ray photons are incident, the detection element 130 directly converts the incident X-rays into electrical charges and outputs them to the ASIC 134.

[0051] The ASIC 134 counts the number of X-ray photons incident on the detection element 130 by distinguishing the individual charges output from the detection element 130. Furthermore, the ASIC 134 measures the energy of the counted X-ray photons by performing calculations based on the magnitude of each charge. The ASIC 134 includes, for example, a capacitor 134a, an amplifier circuit 134b, a waveform shaping circuit 134c, a comparator circuit 134d, and a counter 134e. The ASIC 134 is an example of a counting circuit.

[0052] Capacitor 134a stores the charge output by detection element 130. Amplification circuit 134b is a circuit that integrates, amplifies, and outputs a pulse signal of electrical charge as a result of X-ray photons incident on detection element 130, thereby responsive to X-ray photons. The wave height or area of ​​this pulse signal is correlated with the energy of the photon.

[0053] Here, the amplifier circuit 134b includes, for example, an amplifier. The amplifier is, for example, a single-wire grounded (single-ended) amplifier. In the case of a single-wire grounded amplifier, the amplifier is grounded, amplifying the potential difference between the ground potential (ground) and the potential indicated by the electrical signal output from the detection element 130. Alternatively, the amplifier can be a differential amplifier. In the case of a differential amplifier, the positive input (+) of the amplifier is connected to the detection element 130, and the negative input (-) is grounded. Furthermore, the differential amplifier amplifies the potential difference between the potential indicated by the electrical signal input to the positive input from the detection element 130 and the ground potential indicated by the signal input to the negative input.

[0054] The waveform shaping circuit 134c is a circuit that shapes the waveform of the pulse signal by adjusting the frequency characteristics of the pulse signal output from the amplifier circuit 134b and by assigning gain and offset.

[0055] The comparator circuit 134d compares the wave height or area of ​​the response pulse signal to the incident photon with a preset threshold corresponding to multiple energy bands that should be identified, and outputs the comparison result with the threshold to the subsequent counter 134e.

[0056] Counter 134e counts the waveform discrimination results of the response pulse signal according to each corresponding energy band, and outputs the photon count results as digital data to data collection circuit 14. For example, counter 134e generates digital data representing the count results of X-ray photons for each of multiple energy bands, and outputs the generated digital data to data collection circuit 14.

[0057] According to the above structure, the X-ray detector 13 detects X-ray photons and obtains energy information. Alternatively, the X-ray detector 13 can also be an indirect conversion type photon counting detector, for example, comprising a grid, a scintillator array, and a photodetector array. The scintillator array comprises multiple scintillators, each composed of a scintillator crystal that outputs a quantity of light corresponding to the energy of the incident X-rays. The grid is disposed on the X-ray incident side of the scintillator array and is composed of an X-ray shield that absorbs scattered X-rays. The photodetector array has the function of converting the light from the scintillators into an electrical signal corresponding to the amount of light from the scintillators, and is composed, for example, of a photodetector such as a photomultiplier tube. Here, the photodetector is, for example, a PD (photodiode), an APD (avalanche photodiode), or a SiPM (silicon photomultiplier tube).

[0058] Figure 3 This diagram illustrates an example of multiple energy bands that the X-ray detector 13 of the first embodiment can use when generating digital data. For example, the X-ray detector 13 can use six energy bands 40a to 40f when generating digital data.

[0059] exist Figure 3In the example, band 40a is the band with energy values ​​above 41a and below 41b. Band 40b is the band with energy values ​​above 41b and below 41c. Band 40c is the band with energy values ​​above 41c and below 41d. Band 40d is the band with energy values ​​above 41d and below 41e. Band 40e is the band with energy values ​​above 41e and below 41f. Band 40f is the band with energy values ​​above 41f and below 41g.

[0060] That is, the boundary between two adjacent energy bands 40a and 40b is represented by the energy value 41b. The same applies to the boundaries between other adjacent energy bands.

[0061] In this first embodiment, the X-ray detector 13 is controlled by the processing circuit 37 to set the energy bands used for generating digital data from the six energy bands 40a to 40f. For example, the X-ray detector 13 may set one energy band 40b or set all six energy bands 40a to 40f.

[0062] However, in the first embodiment, the widths of each of the six energy bands 40a to 40f are fixed values. Furthermore, in the first embodiment, the energy values ​​representing the boundaries of two adjacent energy bands are also fixed values. Thus, the X-ray detector 13 cannot change the widths of each of the six energy bands 40a to 40f. Additionally, the X-ray detector 13 cannot change the energy values ​​representing the boundaries of two adjacent energy bands. Therefore, the X-ray detector 13 cannot reset the energy bands. That is, in the first embodiment, the X-ray detector 13 cannot set arbitrary energy bands.

[0063] Return to Figure 1 As explained, the data acquisition circuit 14 (DAS: Data Acquisition System) is a circuit that collects the results of counting processing from each detection element 130 of the X-ray detector 13 and generates detection data (projection data). In other words, the data acquisition circuit 14 collects the counting results of the X-ray detector 13. Here, the detection data is, for example, a sine wave. A sine wave refers to data that arranges the results of counting processing incident at each position of the X-ray tube 12a onto each detection element 130. That is, the sine wave represents the counting results of each energy band of X-ray photons incident at each position of the X-ray tube 12a onto each detection element 130. The data acquisition circuit 14 collects the results of counting processing from each viewing angle of the X-ray detector 13 and generates a sine wave.

[0064] The examination table 20 is a device for placing and moving the subject P to be scanned, and includes an examination table drive device 21, a top plate 22, a base 23 and a base (support frame) 24.

[0065] The top plate 22 is a plate on which the subject P is placed. The base 24 supports the top plate 22. The platform 23 is a frame that supports the base 24 and is capable of moving in the vertical direction. The examination table drive device 21 is a motor or actuator that moves the top plate 22 on which the subject P is placed in the long axis direction of the top plate 22, thereby moving the subject P into the rotating frame 15. In addition, the examination table drive device 21 can also move the top plate 22 in the X-axis direction.

[0066] Furthermore, the method of moving the top plate can involve moving only the top plate 22, or moving it together with the base 24 of the examination bed 20. Additionally, in the case of an upright CT scan, the method can involve moving the patient movement mechanism corresponding to the top plate 22.

[0067] Additionally, the stage 10 may perform a spiral scan, for example, in which the rotating frame 15 is rotated while the top plate 22 is moved, thus scanning the subject P in a spiral pattern. Alternatively, the stage 10 may perform a conventional scan, in which the rotating frame 15 is rotated while the position of the subject P remains fixed after the top plate 22 is moved, thereby scanning the subject P on a circular track. Furthermore, in the following embodiments, the change in the relative position between the stage 10 and the top plate 22 is described by controlling the top plate 22, but the embodiments are not limited to this. For example, if the stage 10 is self-propelled, the change in the relative position between the stage 10 and the top plate 22 can also be achieved by controlling the movement of the stage 10. Alternatively, the change in the relative position between the stage 10 and the top plate 22 can also be achieved by controlling the movement of the stage 10 and the top plate 22.

[0068] The control console 30 is a device that receives operator input on the X-ray CT apparatus 1 and reconstructs X-ray CT image data using the sine wave (counting results) collected by the stage 10. The control console 30 is as follows... Figure 1 As shown, it has an input interface 31, a display 32, a memory 35, and a processing circuit 37.

[0069] Input interface 31 accepts various input operations from the operator, converts the received input operations into electrical signals, and outputs them to processing circuit 37. For example, input interface 31 receives from the operator the collection conditions when collecting projection data, the reconstruction conditions when reconstructing X-ray CT image data, and the image processing conditions when generating image data (post-processed image data) based on X-ray CT image data. For example, input interface 31 can be implemented using a mouse, keyboard, trackball, switch, button, joystick, etc.

[0070] Display 32 displays various information. For example, display 32 outputs images (X-ray CT images) based on image data generated by processing circuit 37, and a GUI (Graphical User Interface) for accepting various operations from the operator. For example, display 32 may be composed of a liquid crystal display, a CRT (Cathode Ray Tube) display, etc.

[0071] The memory 35 is implemented, for example, by semiconductor memory elements such as RAM (Random Access Memory), flash memory, hard disk, optical disk, etc. The memory 35 stores, for example, projection data and reconstructed image data. Additionally, the memory 35 stores an energy meter 35a. The memory 35 is an example of a storage unit. The energy meter 35a will be described later.

[0072] The processing circuit 37, for example, executes system control functions 371, preprocessing functions 372, reconstruction processing functions 373, image processing functions 374, scanning control functions 375, display control functions 376, acquisition functions 377, and decision functions 378. Here, for example, as... Figure 1 The system control function 371, preprocessing function 372, reconstruction processing function 373, image processing function 374, scanning control function 375, display control function 376, acquisition function 377, and decision function 378 of the processing circuit 37 shown are all executed and their respective processing functions are recorded in the memory 35 as computer-executable programs. The processing circuit 37 is implemented, for example, by a processor. The processing circuit 37 reads each program from the memory 35 and executes each read program to implement the function corresponding to that program. In other words, the processing circuit 37, after reading the state of each program, has... Figure 1 The functions shown in the processing circuit 37.

[0073] The system control function 371 controls various functions of the processing circuit 37 based on input operations received from the operator via the input interface 31.

[0074] The preprocessing function 372 performs logarithmic transformation, offset correction, inter-channel sensitivity correction, inter-channel gain correction, pile-up correction, response function correction, and beam hardening correction on the detection data output from the data acquisition circuit 14 to generate raw data. The preprocessing function 372 stores the raw data in the memory 35.

[0075] Furthermore, as mentioned above, the data output from the data acquisition circuit 14 is called detection data, and the data after preprocessing such as logarithmic transformation, offset correction, inter-channel sensitivity correction, inter-channel gain correction, stacking correction, response function correction, and beam hardening correction is called raw data. Additionally, both the detection data and the raw data are collectively referred to as projection data.

[0076] The reconstruction processing function 373 performs reconstruction processing on the raw data generated by the preprocessing function 372 using methods such as filtered correction back projection or iterative approximate reconstruction, to generate X-ray CT image data. The reconstruction processing function 373 saves the reconstructed X-ray CT image data in the memory 35.

[0077] Here, the projection data generated based on the sine wave (counting result) obtained from photon-counting CT includes information about the energy of the X-rays that are attenuated by passing through the subject P. Therefore, the reconstruction processing function 373 can, for example, reconstruct X-ray CT image data of a specific energy component. Furthermore, the reconstruction processing function 373 can, for example, reconstruct X-ray CT image data of multiple energy components individually.

[0078] Furthermore, the reconstruction processing function 373, for example, assigns a hue corresponding to the energy component to each pixel of the X-ray CT image data for each energy component, generating image data that overlaps multiple X-ray CT image data separated by energy components. Additionally, the reconstruction processing function 373 can, for example, utilize the inherent K absorption end of a substance to generate image data capable of identifying that substance. Other image data generated by the reconstruction processing function 373 include monochromatic X-ray image data, density image data, and effective atomic number image data.

[0079] Furthermore, as an application of X-ray CT, there is a technique that utilizes the absorption characteristics of X-rays to identify the type, quantity, density, etc., of substances contained in a specimen P, depending on the specific substance. This is called substance identification. For example, the reconstruction processing function 373 performs substance identification on the projection data to obtain substance identification information. Then, the reconstruction processing function 373 uses the result of substance identification, i.e., the substance identification information, to reconstruct substance identification image data representing the substance identification image.

[0080] When reconstructing X-ray CT image data, the reconstruction processing function 373 can apply both full-scan reconstruction and half-scan reconstruction modes. For example, in the full-scan reconstruction mode, the reconstruction processing function 373 requires projection data of 360 degrees around the subject. Conversely, in the half-scan reconstruction mode, the reconstruction processing function 373 requires projection data of 180 degrees plus a sector angle. For simplicity, the following explanation will assume that the reconstruction processing function 373 uses the full-scan reconstruction mode, reconstructing the circumference of the subject using 360 degrees of projection data.

[0081] Image processing function 374, based on input operations received from the operator via input interface 31, transforms the X-ray CT image data generated by reconstruction processing function 373 into various image data such as tomographic image data of arbitrary sections and 3D image data based on rendering processing, using known methods. Furthermore, when scan control function 375 performs the monitoring scan described later, image processing function 374 transforms the X-ray CT image data into monitoring image data using known methods. Image processing function 374 stores the transformed image data in memory 35.

[0082] The scan control function 375 controls the CT scan performed by the gantry 10. For example, the scan control function 375 controls the start, execution, and end of the scan in the gantry 10 by controlling the operation of the X-ray high-voltage device 11, the X-ray detector 13, the gantry control device 16, the data acquisition circuit 14, and the examination bed drive device 21. Specifically, the scan control function 375 controls the collection and processing of projection data in the positioning imaging (positioning scan) that collects positioning image data (scanning image data) representing positioning images (scanning images) and the formal imaging (formal scan) that collects image data representing images used for diagnosis, based on the examination protocol selected by the user such as the radiology technician or physician.

[0083] Here, an example of the steps by which the scan control function 375 accepts an inspection protocol selected by the user will be described. For example, the scan control function 375 causes the display 32 to show a human model of the subject P. The user selects a part of the human model displayed on the display 32 for imaging (imaging part, subject part) via the input interface 31. Then, the scan control function 375 causes the display 32 to display multiple preset inspection protocols for the imaging part selected by the user in a selectable manner. The user selects an inspection protocol for imaging from the multiple inspection protocols displayed on the display 32 via the input interface 31. Then, the scan control function 375 accepts the inspection protocol selected by the user as the inspection protocol to be used in imaging.

[0084] The scan control function 375 can capture both 2D and 3D scan image data. For example, the scan control function 375 fixes the X-ray tube 12a at a 0-degree position (the frontal position relative to the subject P) and continuously captures images while moving the top plate 22 at a constant speed, thereby capturing 2D scan image data. Alternatively, the scan control function 375 fixes the X-ray tube 12a at a 0-degree position and intermittently moves the top plate 22, repeatedly capturing images intermittently in sync with the movement of the top plate 22, thereby capturing 2D scan image data. Furthermore, the scan control function 375 can capture scan image data not only from the frontal position relative to the subject P but also from any direction (e.g., the side position). For example, if the X-ray tube 12a is captured at a 90-degree position (the side position relative to the subject P), a 2D scan image can be captured from the side of the subject P. Additionally, if needed, the X-ray tube 12a can be positioned from multiple possible positions for capturing images.

[0085] Furthermore, during the acquisition of scanned image data, the scan control function 375 collects projection data of an amount covering the entire circumference of the subject, thereby capturing 3D scanned image data. For example, the scan control function 375 collects projection data of an amount covering the entire circumference of the subject using either helical or non-helical scanning. Here, the scan control function 375 performs helical or non-helical scanning on a large area of ​​the subject, such as the entire chest, abdomen, upper body, or whole body, at a dose lower than that of a standard scan. For example, a step-by-step scan is performed as a non-helical scan.

[0086] In addition, during angiography, the scan control function 375 performs a monitoring scan (prep scan) to observe the contrast agent concentration after injecting the contrast agent into the subject P, based on the examination protocol selected by the user. For example, an iodine contrast agent is used. Here, the monitoring scan is an image taken to observe the concentration change of the contrast agent in a region of interest set on the tomographic image of the subject P, i.e., the monitoring image. During the monitoring scan, the scan control function 375 detects the CT value that increases accordingly with the concentration of the contrast agent injected into the subject P in the region of interest set on the monitoring image, and automatically or upon user instruction, switches to the formal scan when the CT value reaches a threshold. Furthermore, although the monitoring scan does not contribute to diagnosis, it can switch to the formal scan when the contrast agent concentration is high, thus contributing to the improvement of the image quality of the X-ray CT image data obtained by the formal scan.

[0087] Display control function 376 controls the display 32 to show images based on various image data stored in memory 35. For example, display control function 376 causes display 32 to show a monitoring image based on monitoring image data.

[0088] Acquisition function 377 acquires information related to the imaging mode. Determination function 378, based on the information related to the imaging mode acquired by acquisition function 377, determines conditions related to the energy bands of the projection data collected from X-ray detector 13. Acquisition function 377 is an example of an acquisition unit. Determination function 378 is an example of a determination unit. Further details regarding acquisition function 377 and determination function 378 will be described later.

[0089] The structure of the X-ray CT apparatus 1 according to the first embodiment has been described above. Here, in photon counting CT, the optimal band setting differs depending on the imaging mode. Therefore, the X-ray CT apparatus 1 of the first embodiment performs various processes described below to determine the optimal band based on the imaging mode.

[0090] Figure 4 This is a diagram illustrating an example of the data structure of the energy table 35a in the first embodiment. (See diagram for example.) Figure 4 As shown, energy table 35a contains records of various items, each with a "shooting mode" and a "bandwidth". Here, in the first embodiment, shooting mode refers to various types (purposes) of shooting, such as monitoring scan, spiral scan in formal scanning, and conventional scan in formal scanning.

[0091] The "Shooting Mode" section contains information indicating the shooting mode. For example, such as... Figure 4 As shown, "surveillance scan" is registered in the first recorded "shooting mode" item. Additionally, as... Figure 4 As shown, the "Shooting Mode" section of the second record lists "Helical scan in formal scanning." Thus, the "Shooting Mode" section contains information related to the shooting mode.

[0092] The "Band Size" section lists the optimal band size corresponding to the shooting mode listed in the "Shooting Mode" section. For example, in monitoring scans, it is sufficient to confirm the concentration of the iodine contrast agent. Iodine contrast agents emphasize contrast effects in lower band sizes (e.g., bands with energy values ​​above 41b and below 41c). Therefore, as... Figure 4 As shown, the first recorded "Band" item lists the optimal band "energy value 41b~41c" corresponding to "monitoring scan". This band "energy value 41b~41c" refers to a band with an energy value of 41b or higher but less than 41c.

[0093] Furthermore, when performing helical scanning during a formal scan, the X-ray CT device 1 may require acquiring a large amount of energy information to obtain clinical data. In this case, to maximize the energy range and extract features, increasing the number of energy bands is considered. Therefore, as... Figure 4 As shown, the second record's "Band" item lists the optimal band values ​​corresponding to "helical scan in formal scanning": "energy values ​​41a~41b, 41b~41c, 41c~41d, 41d~41e, 41e~41f, 41f~41g". These band values ​​"energy values ​​41a~41b, 41b~41c, 41c~41d, 41d~41e, 41e~41f, 41f~41g" represent bands with energy values ​​above 41a and below 41b, above 41b and below 41c, above 41c and below 41d, above 41d and below 41e, above 41e and below 41f, and above 41f and below 41g.

[0094] Next, the procedure for the first bandgap determination process performed by the X-ray CT apparatus 1 will be described. The first bandgap determination process is used to determine the bands used by the X-ray detector 13 when generating the digital data described above. Figure 5 This is a flowchart illustrating an example of the first band determination process performed by the X-ray CT apparatus 1 according to the first embodiment.

[0095] like Figure 5 As shown, the acquisition function 377 acquires the shooting mode (predetermined shooting mode to be executed) of the object to be executed (step S101). For example, the memory 35 stores the inspection protocol selected by the user. The acquisition function 377 acquires the inspection protocol selected by the user from the memory 35, and acquires the shooting mode from the acquired inspection protocol. For example, the acquisition function 377 acquires "monitoring scan", "spiral scan in formal scan", etc. as shooting modes. In this way, the acquisition function 377 acquires information related to the shooting mode.

[0096] Then, the determination function 378 obtains the optimal energy band corresponding to the shooting mode obtained in step S101 from the energy table 35a (step S102). For example, if the shooting mode "monitoring scan" is obtained in step S101, in step S102, the determination function 378 refers to the energy table 35a and obtains the energy band "energy values ​​41b to 41c". In addition, if the shooting mode "helical scan in formal scan" is obtained in step S101, in step S102, the determination function 378 refers to the energy table 35a and obtains the energy band "energy values ​​41a to 41b, 41b to 41c, 41c to 41d, 41d to 41e, 41e to 41f, 41f to 41g".

[0097] Then, the determination function 378 determines the band corresponding to the band obtained from the six bands 40a to 40f in step S102 as the band for shooting (scanning) in the shooting mode obtained in step S101 (step S103).

[0098] For example, the case where the band energy values ​​"41b to 41c" are obtained in step S102 will be explained. Figure 6 This diagram illustrates an example of the energy band determined in the first embodiment. In this case, in step S103, the determination function 378 is as follows: Figure 6 As shown, energy band 40b, which corresponds to the energy values ​​41b to 41c, is determined as the energy band for monitoring and scanning.

[0099] Furthermore, for example, let's describe the case where the band energy values ​​"41a~41b, 41b~41c, 41c~41d, 41d~41e, 41e~41f, 41f~41g" are obtained in step S102. In this case, in step S103, the function 378 is determined as before. Figure 3 As shown, six energy bands 40a to 40f, corresponding to the energy values ​​41a to 41b, 41b to 41c, 41c to 41d, 41d to 41e, 41e to 41f, and 41f to 41g, are determined as the energy bands in the case of helical scanning during the formal scanning.

[0100] Then, the determination function 378 sets the X-ray detector 13 to the energy band determined in step S103 as the energy band for taking pictures in the imaging mode obtained in step S101 (step S104). For example, if the determination function 378 determines the energy band 40b in step S103, in step S104, the X-ray detector 13 is set to the energy band 40b as the energy band for taking pictures in the "monitoring scan" imaging mode.

[0101] Furthermore, if the determination function 378 determines the energy bands 40a to 40f in step S103, it sets the X-ray detector 13 to the energy bands 40a to 40f as the energy bands for performing the imaging mode "helical scan in formal scanning". Then, the determination function 378 ends the first energy band determination process.

[0102] Specific examples will be given to illustrate the processing of step S104. For instance, in step S104, the decision function 378 first determines the conditions (first conditions) related to the energy bands of the data collected from the X-ray detector 13 based on the acquired imaging mode. These first conditions include the range of each energy band, the number of energy bands, and merging information. Here, the merging information includes information indicating whether at least two of the multiple energy bands 40a to 40f should be merged, and information representing the merged energy bands if merging is involved.

[0103] For example, if band 40b is determined in step S103, in step S104, the determination function 378 determines a first condition indicating that the band range is above energy value 41b and below energy value 41c, and the number of bands is "1". Furthermore, the merging information included in the first condition includes information indicating no merging. In step S104, the determination function 378 sends the determined first condition to the X-ray detector 13.

[0104] Upon receiving the first condition, the X-ray detector 13 sets the energy band in a manner that matches the first condition. For example, the X-ray detector 13 sets one energy band 40b in a manner that matches the first condition. Then, the X-ray detector 13 acquires the energy information of the set energy band.

[0105] The following describes the band situation where band 40b is set to the "monitoring scan" imaging mode during the first band determination process. In this case, during the monitor scan, the X-ray detector 13 generates digital data representing the count results of X-ray photons in band 40b out of the six bands 40a to 40f, and outputs the generated digital data to the data collection circuit 14. In this case, the X-ray detector 13 does not count the individual X-ray photons in the other five bands 40a, 40c to 40f (no counting). That is, the X-ray detector 13 does not generate digital data representing the count results of X-ray photons in each of the five bands 40a, 40c to 40f.

[0106] Furthermore, the X-ray detector 13 may not output digital data representing the count results of X-ray photons in each of the five energy bands 40a, 40c to 40f, but instead output digital data representing the count results of X-ray photons in energy band 40b. The digital data output from the X-ray detector 13 does not include the count results of X-ray photons in energy bands 40a, 40c to 40d other than energy band 40b.

[0107] In general, during photon-counting CT imaging, there is a tendency for the data size (information content) of the data output from the X-ray detector to be relatively large in order to obtain band information. However, according to the first embodiment, by optimizing the band according to the imaging mode, it is possible to suppress the increase in the data size of the digital data output from the X-ray detector 13. Furthermore, it is possible to suppress the increase in the data size of the raw data stored in the memory 35 of the control console 30.

[0108] Furthermore, the digital data representing the count results of X-ray photons with a band density of 40 Å is processed by the data acquisition circuit 14, preprocessing function 372, reconstruction processing function 373, and image processing function 374 to become monitoring image data. Then, the monitoring image based on the monitoring image data is displayed on the display 32 via the display control function 376. Figure 7 This is a diagram illustrating an example of the monitoring image 43 in the first embodiment. Figure 7 The iodine contrast agent 43a is clearly depicted in the monitoring image 43 shown. Therefore, according to the first embodiment, an effective energy band corresponding to the shooting mode is determined, thus enabling the generation of monitoring image data with the value of effectively performing monitoring scans.

[0109] Furthermore, the X-ray CT apparatus 1 of the first embodiment automatically optimizes the energy band according to the imaging mode. For example, the X-ray CT apparatus 1 automatically determines and sets the optimal energy band 40b among the six energy bands 40a to 40f. Therefore, according to the first embodiment, the optimal energy band can be automatically determined according to the imaging mode. Therefore, according to the first embodiment, compared with the case where the user manually sets the energy band, the burden on the user during setup or imaging can be reduced. In addition, improvements in the workflow can be anticipated.

[0110] Furthermore, according to the first embodiment, since the energy band is automatically set, the user can undergo a photon-counting CT scan without realizing that it is a photon-counting CT scan, and with the same feeling as a normal CT scan without setting the energy band.

[0111] Next, the band situation will be described when the six bands 40a to 40f are set to the imaging mode "helical scan in formal scan" during the first band determination process. In this case, during the formal scan, the X-ray detector 13 generates digital data representing the count results of X-ray photons for each of the six bands 40a to 40f, and outputs the generated digital data to the data collection circuit 14.

[0112] The digital data is then processed by the data collection circuit 14, preprocessing function 372, reconstruction processing function 373, and image processing function 374 to become image data. The image based on the image data is then displayed on the display 32 via the display control function 376. Figure 8 This is a diagram illustrating an example of image 44 from the first embodiment. Figure 8 The image 44 shown clearly depicts a great deal of energy band information required for clinical examination. Therefore, according to the first embodiment, the effective energy bands corresponding to the imaging mode are determined, so image data with value for effectively identifying and observing lesions can be generated.

[0113] Furthermore, the X-ray CT device 1 automatically determines and sets six energy bands 40a to 40f according to the imaging mode. This reduces the burden on the user during setup and imaging, and can be expected to improve the workflow. Additionally, the user can undergo a photon-count CT examination without realizing it is a photon-count CT scan, experiencing the same sensation as a regular CT scan without setting energy bands.

[0114] Furthermore, in the "Shooting Mode" section of the energy meter 35a, in addition to the aforementioned "Monitoring Scan" and "Helical Scan in Formal Scan," various other shooting modes are also registered. Therefore, the optimal energy bands corresponding to these other shooting modes are registered in the "Energy Band" section. Hereinafter, a specific example of the processing performed in step S103 when the determination function 378 has obtained various energy bands in step S102 will be explained.

[0115] Figures 9-13 This is a diagram illustrating an example of the process performed in step S103 when the decision function 378 of the first embodiment obtains other various energy bands in step S102.

[0116] For example, the case where the decision function 378 obtains the band energy values ​​"41b~41c, 41c~41d" in step S102 will be explained. These band energy values ​​"41b~41c, 41c~41d" represent bands with energy values ​​above 41b and below 41c, and bands with energy values ​​above 41c and below 41d. In this case, in step S103, as... Figure 9 As shown, the determination function 378 determines the two energy bands 40b and 40c corresponding to the energy bands “energy values ​​41b~41c, 41c~41d” as the energy bands for shooting in the shooting mode obtained in step S101.

[0117] Furthermore, for example, let's explain the case where the decision function 378 obtains the band energy values ​​"41b~41c, 41d~41e, 41e~41f" in step S102. These band energy values ​​"41b~41c, 41d~41e, 41e~41f" represent bands with energy values ​​41b or higher and lower than 41c, bands with energy values ​​41d or higher and lower than 41e, and bands with energy values ​​41e or higher and lower than 41f. In this case, in step S103, as... Figure 10 As shown, the determination function 378 determines the three energy bands 40b, 40d, and 40e corresponding to the energy bands “energy values ​​41b~41c, 41d~41e, 41e~41f” as the energy bands for shooting in the shooting mode obtained in step S101.

[0118] Furthermore, for example, let's explain the case where the decision function 378 obtains the band energy values ​​"41b~41c, 41c~41d, 41d~41g" in step S102. These band energy values ​​"41b~41c, 41c~41d, 41d~41g" represent bands with energy values ​​41b or higher and lower than 41c, bands with energy values ​​41c or higher and lower than 41d, and bands with energy values ​​41d or higher and lower than 41g. In this case, in step S103, as... Figure 11 As shown, the decision function 378 determines the three energy bands 40b, 40d, and 40g corresponding to the energy bands "energy values ​​41b-41c, 41c-41d, and 41d-41g" as the energy bands for shooting in the shooting mode obtained in step S101. Here, the energy bands "energy values ​​41d-41g" correspond to the three energy bands 40d-40f. Therefore, the decision function 378 combines the three energy bands 40d-40f into one energy band 40g. That is, the decision function 378 uses the one energy band obtained by merging the three energy bands 40d-40f as energy band 40g.

[0119] In this case, the first condition sent to the X-ray detector 13 in step S104 will be explained. In this first condition, the range of each energy band includes the following: the first energy band range is the range of energy values ​​41b and above and less than energy value 41c; the second energy band range is the range of energy values ​​41c and above and less than energy value 41d; and the third energy band range is the range of energy values ​​41d and above and less than energy value 41g. Furthermore, the first condition includes the number of energy bands as "3". Additionally, the merging information included in the first condition includes information indicating that the three energy bands 40d, 40e, and 40f are merged.

[0120] Upon receiving such a first condition, the X-ray detector 13 sets the energy bands in a manner matching the first condition. For example, the X-ray detector 13 sets three energy bands 40b, 40c, and 40g in a manner matching the first condition. Here, the X-ray detector 13 sets one energy band 40g by merging three energy bands 40d, 40e, and 40f. Furthermore, the X-ray detector 13 acquires the energy information of the set three energy bands 40b, 40c, and 40g.

[0121] Additionally, for example, in step S102, the decision function 378 obtains the band energy values ​​"41a-41b, 41b-41c, 41c-41d, 41d-41g". These band energy values ​​"41a-41b, 41b-41c, 41c-41d, 41d-41g" represent bands with energy values ​​41a and above but less than 41b, bands with energy values ​​41b and above but less than 41c, bands with energy values ​​41c and above but less than 41d, and bands with energy values ​​41d and above but less than 41g. In this case, in step S103, as... Figure 12 As shown, the determination function 378 determines the four energy bands 40a, 40b, 40d, and 40g corresponding to the energy bands “energy values ​​41a~41b, 41b~41c, 41c~41d, 41d~41g” as the energy bands for shooting in the shooting mode obtained in step S101.

[0122] Additionally, for example, consider the case where the decision function 378 obtains the band energy value "41a to 41g" in step S102. This band energy value "41a to 41g" refers to a band with an energy value greater than 41a and less than 41g. In this case, in step S103, as... Figure 13As shown, the determination function 378 determines one energy band 40h corresponding to the energy band "energy values ​​41a to 41g" as the energy band for shooting in the shooting mode obtained in step S101. Here, the energy bands "energy values ​​41a to 41g" correspond to six energy bands 40a to 40f. Therefore, the determination function 378 combines the six energy bands 40a to 40f into one energy band 40h. That is, the determination function 378 uses the one energy band obtained by merging the six energy bands 40a to 40f as energy band 40h.

[0123] The X-ray CT apparatus 1 according to the first embodiment has been described above. According to the first embodiment, as described above, the optimal energy band can be determined according to the imaging mode.

[0124] (A variation of the first embodiment)

[0125] In the first embodiment described above, the case where the X-ray CT apparatus 1 determines the optimal bandgap based on the imaging mode was explained. Here, the X-ray CT apparatus 1 is capable of performing CT fluoroscopy. CT fluoroscopy is an imaging method for continuously irradiating a subject P with X-rays based on a lower tube current compared to a formal scan and generating image data of the region of interest of the subject P in real time. CT fluoroscopy is performed, for example, to guide medical devices such as puncture needles used in biopsy. Here, the X-ray CT apparatus 1 can also determine the optimal bandgap based on the type of medical device used in the examination. Therefore, such a modification is described as a modification of the first embodiment. In addition, in the description of the modification of the first embodiment, the differences from the first embodiment are mainly described, and the same structures as the first embodiment are sometimes omitted from the description.

[0126] Figure 14 This is a diagram illustrating an example of the data structure of the energy table 35b in a variation of the first embodiment. In the variation of the first embodiment, Figure 14 The energy table 35b shown is stored in memory 35. For example... Figure 14 As shown, there are multiple records in energy table 35b, which include items for "medical equipment" and "energy band".

[0127] The "Medical Equipment" category includes information indicating the type of medical equipment used during filming. For example, such as... Figure 14 As shown, "puncture needle" is registered in the first record under the "medical devices" category. Thus, information related to medical devices is registered in the "medical devices" category.

[0128] In the "Band Size" section, the optimal band size corresponding to the type of medical device represented by the information registered in the "Medical Device" section is specified. For example, in CT fluoroscopy, it is preferable that the puncture needle is clearly depicted in the image displayed on monitor 32. Here, for example, the band size in which the puncture needle is clearly depicted in the image is a band with an energy value of 41b or higher and less than an energy value of 41c, and a band with an energy value of 41c or higher and less than an energy value of 41d. In this case, as... Figure 14 As shown, the first recorded "band" item has the optimal band values ​​"41b~41c, 41c~41d" corresponding to the "puncture needle".

[0129] Next, the process of the second band determination process performed by the X-ray CT apparatus 1 in a variation of the first embodiment will be described. The second band determination process is used to determine the band used by the X-ray detector 13 when generating the digital data described above. Figure 15 This is a flowchart illustrating an example of the second band determination process performed by the X-ray CT apparatus 1, a variant of the first embodiment.

[0130] like Figure 15 As shown, the acquisition function 377 acquires information indicating the type of medical device used during imaging (step S201). For example, information indicating the type of medical device used during imaging is stored in memory 35. The acquisition function 377 acquires the information indicating the type of medical device used during imaging from memory 35. For example, the acquisition function 377 acquires information indicating a puncture needle. In this way, the acquisition function 377 acquires information related to the medical device.

[0131] Then, the determination function 378 obtains the optimal energy band corresponding to the type of medical device shown in the information obtained in step S201 from the energy table 35b (step S202). For example, if the information indicating the puncture needle is obtained in step S201, in step S202, the determination function 378 refers to the energy table 35b and obtains the energy band "energy values ​​41b to 41c, 41c to 41d".

[0132] Then, the determination function 378 determines the band corresponding to the band obtained from the six bands 40a to 40f in step S202 as the band for imaging (scanning) using the type of medical device shown in the information obtained in step S201 (step S203). The case where the band "energy values ​​41b to 41c, 41c to 41d" were obtained in step S202 will be explained. In this case, in step S203, as previously described... Figure 9As shown, the determination function 378 determines the two energy bands 40b and 40c corresponding to the energy bands “energy values ​​41b~41c, 41c~41d” as the energy bands for imaging (CT fluoroscopy) using a puncture needle.

[0133] Then, the determination function 378 sets the X-ray detector 13 to the energy band determined in step S203 as the energy band for imaging using the type of medical device indicated by the information obtained in step S201 (step S204). For example, if the determination function 378 determines two energy bands 40b and 40c in step S203, then in step S204, the X-ray detector 13 sets the two energy bands 40b and 40c as the energy band for CT fluoroscopy using a puncture needle. Then, the determination function 378 ends the second energy band determination process.

[0134] For example, in step S204, the decision function 378 first determines a first condition based on the type of medical device shown in the acquired information. Then, in step S204, the decision function 378 sends the determined first condition to the X-ray detector 13.

[0135] The X-ray CT apparatus 1 of the modified embodiment of the first embodiment has been described above. According to the modified embodiment of the first embodiment, the bandgap is optimized according to the type of medical equipment used for imaging, thereby suppressing the increase in the data size of the digital data output from the X-ray detector 13. Furthermore, it is possible to suppress the increase in the data size of the raw data stored in the memory 35 of the control console 30.

[0136] Furthermore, in a variation of the first embodiment, for example, an image of the puncture needle clearly depicted during CT fluoroscopy is displayed on the display 32. Therefore, according to the variation of the first embodiment, an effective energy band corresponding to the type of medical device is determined, thus enabling the generation of image data with the value of effectively performing CT fluoroscopy.

[0137] Furthermore, in the modified X-ray CT apparatus 1 of the first embodiment, the energy band is automatically optimized according to the type of medical device. Specifically, for example, the X-ray CT apparatus 1 automatically determines and sets the two optimal energy bands 40b and 40c out of the six energy bands 40a to 40f. Therefore, according to the modified first embodiment, the optimal energy band can be automatically determined according to the type of medical device. Therefore, according to the modified first embodiment, compared with the case where the user manually sets the energy band, the burden on the user during setup or imaging can be reduced. In addition, improvements in the workflow can be anticipated. Furthermore, according to the modified first embodiment, since the energy band is automatically set, the user can undergo a photon-count CT examination with the same feeling as a normal CT scan without setting the energy band, without realizing that it is a photon-count CT scan.

[0138] (Second Implementation)

[0139] In the first embodiment described above, the optimal energy band of the X-ray CT apparatus 1 was determined based on the imaging mode. Furthermore, in a variation of the first embodiment, the optimal energy band of the X-ray CT apparatus 1 was determined based on the type of medical device. However, the optimal energy band of the X-ray CT apparatus 1 can also be determined based on the imaging site. Therefore, this embodiment will be described as the second embodiment. In the description of the second embodiment, the differences from the first embodiment and its variations will be mainly explained; descriptions of structures identical to those in the first embodiment and its variations are sometimes omitted.

[0140] Figure 16 This is a diagram illustrating an example of the data structure of the energy table 35c in the second embodiment. (See diagram for example.) Figure 16 As shown, multiple records are registered in energy meter 35c, which includes items such as "shooting location" and "energy band".

[0141] The "Shooting Location" section includes information indicating the shooting location. For example, such as... Figure 16 As shown, "chest" is registered in the "Shooting Location" field of the first record. Additionally, "head" is registered in the "Shooting Location" field of the second record. Thus, information related to the shooting location is registered in the "Shooting Location" field.

[0142] The "Band Size" field lists the optimal band size corresponding to the imaging site indicated by the information listed in the "Imaging Site" field. For example, consider imaging the chest of subject P. In this case, the soft tissue of the chest is preferably clearly depicted in the resulting image based on image data. Here, for example, the band size in which the soft tissue of the chest is clearly depicted in the image is a band with an energy value of 41a or higher and an energy value of 41b. Therefore, as... Figure 16 As shown, the first recorded "Band" item lists the optimal band "energy value 41a~41b" corresponding to the "chest". This band "energy value 41a~41b" refers to a band with an energy value of 41a or higher but less than 41b.

[0143] Furthermore, for example, let's describe the case of photographing the head of the subject P. In this case, it is preferable to suppress the beam hardening effect caused by the skull. Here, for example, the energy bands in which the beam hardening effect caused by the skull is suppressed are energy bands with energies of 41c and above but less than 41d. Therefore, as... Figure 16 As shown, the second record's "Band" section lists the optimal band energy value "41c-41d" corresponding to the "head". This "41c-41d" band energy value indicates a band with an energy value above 41c and below 41d.

[0144] Next, the process of the third band determination process performed by the X-ray CT apparatus 1 in the second embodiment will be described. The third band determination process is the process used to determine the band used when the X-ray detector 13 generates the digital data described above. Figure 17 This is a flowchart illustrating an example of the third band determination process performed by the X-ray CT apparatus 1 of the second embodiment.

[0145] like Figure 17 As shown, the acquisition function 377 acquires information representing the imaging location (step S301). For example, the acquisition function 377 can also acquire information representing the imaging location selected by the user from multiple parts of the human body model displayed on the display 32, as described above. Alternatively, the acquisition function 377 can perform recognition processing on the scanned image data to automatically identify the parts of the subject P depicted in the scanned image data, and acquire information representing the identified parts as information representing the imaging location. Furthermore, the acquisition function 377 can also acquire information representing the imaging location by receiving it from the user via the input interface 31. In this way, the acquisition function 377 acquires information related to the imaging location.

[0146] Then, the determination function 378 obtains the optimal energy band corresponding to the shooting location shown in the information obtained in step S301 from the energy table 35c (step S302). For example, if information indicating the chest is obtained in step S301, in step S302, the determination function 378 refers to the energy table 35c and obtains the energy band "energy values ​​41a to 41b". Similarly, if information indicating the head is obtained in step S301, in step S302, the determination function 378 refers to the energy table 35c and obtains the energy band "energy values ​​41c to 41d".

[0147] Then, the determination function 378 determines the energy band corresponding to the energy band obtained from the six energy bands 40a to 40f in step S302 as the energy band for photographing the area shown in the information obtained in step S301 (step S303). The case where the energy band "energy values ​​41a to 41b" are obtained in step S302 will be explained. In this case, in step S303, the determination function 378 determines one energy band 40a corresponding to the energy band "energy values ​​41a to 41b" as the energy band for photographing the chest.

[0148] Furthermore, the case where the energy band "energy values ​​41c to 41d" are obtained in step S302 will be explained. In this case, in step S303, the determination function 378 determines one energy band 40c corresponding to the energy band "energy values ​​41c to 41d" as the energy band for the case of shooting the head.

[0149] Then, the determination function 378 sets the X-ray detector 13 to the energy band determined in step S303 as the energy band for imaging the area shown in the information obtained in step S301 (step S304). For example, if the determination function 378 determines energy band 40a in step S303, then in step S304, the X-ray detector 13 sets energy band 40a as the energy band for imaging the chest. Similarly, if the determination function 378 determines energy band 40c in step S303, then in step S304, the X-ray detector 13 sets energy band 40c as the energy band for imaging the head. Then, the determination function 378 ends the third energy band determination process.

[0150] For example, in step S304, the decision function 378 first determines a first condition based on the imaging location shown by the acquired information. Then, in step S304, the decision function 378 sends the determined first condition to the X-ray detector 13.

[0151] The X-ray CT apparatus 1 according to the second embodiment has been described above. According to the second embodiment, by optimizing the enable band according to the imaging location, it is possible to suppress the increase in the data size of the digital data output from the X-ray detector 13. Furthermore, it is possible to suppress the increase in the data size of the raw data stored in the memory 35 of the control console 30.

[0152] Furthermore, in the second embodiment, for example, an image clearly depicting the soft tissue of the chest is displayed on the display 32. Additionally, an image in which the beam hardening effect caused by the skull is suppressed is displayed on the display 32. Therefore, according to the second embodiment, an effective energy band corresponding to the imaging site is determined, thus enabling the generation of image data with value for effective clinical examination.

[0153] Furthermore, the X-ray CT apparatus 1 of the second embodiment automatically optimizes the energy band according to the imaging site. Specifically, for example, the X-ray CT apparatus 1 automatically determines and sets an optimal energy band 40a. Additionally, for example, the X-ray CT apparatus 1 automatically determines and sets an optimal energy band 40c. Therefore, according to the second embodiment, the optimal energy band can be automatically determined according to the imaging site. Therefore, according to the second embodiment, compared to the case where the user manually sets the energy band, the burden on the user during setup or imaging can be reduced. Furthermore, improvements in workflow can be anticipated. Furthermore, according to the second embodiment, since the energy band is automatically set, the user can undergo a photon-count CT examination without realizing it is a photon-count CT scan, experiencing the same sensation as a regular CT scan without setting the energy band.

[0154] (Third Implementation)

[0155] In the first embodiment, variations thereof, and the second embodiment described above, the X-ray CT apparatus 1 was described with the X-ray detector 13 set to an optimal energy band. However, the X-ray CT apparatus 1 can also control the reconstruction processing function 373 by not setting the X-ray detector 13 to an optimal energy band, but by using data representing the count results of X-ray photons in the optimal energy band for reconstruction processing. Therefore, this embodiment will be described as the third embodiment. Furthermore, in the description of the third embodiment, the differences from the first embodiment, variations thereof, and the second embodiment will be mainly explained, and descriptions of structures identical to those in the first embodiment, variations thereof, and the second embodiment will sometimes be omitted.

[0156] In the third embodiment, the X-ray detector 13 uses the six energy bands 40a to 40f directly as is when generating digital data. That is, in the third embodiment, the X-ray detector 13 generates digital data representing the count results of X-ray photons in each of the six energy bands 40a to 40f, and outputs the generated digital data to the data collection circuit 14.

[0157] Furthermore, in the third embodiment, at least one of the energy meters 35a, 35b, and 35c described above is stored in the memory 35. First, the case where energy meter 35a is stored in the memory 35 will be described.

[0158] The procedure for the fourth band determination process performed by the X-ray CT apparatus 1 using energy table 35a will be described. The fourth band determination process is a process used to determine the bands associated with the original data that become the object of the reconstruction process performed based on reconstruction processing function 373. Figure 18 This is a flowchart illustrating an example of the fourth band determination process performed by the X-ray CT apparatus 1 according to the third embodiment.

[0159] like Figure 18 As shown, the acquisition function 377 and the determination function 378 perform the steps S101 to S103 of the first band determination process in the same way. For example, the acquisition function 377 acquires the shooting mode (step S101), and the determination function 378 acquires the optimal band corresponding to the shooting mode acquired in step S101 from the energy table 35a (step S102). Then, the determination function 378 determines the band corresponding to the band acquired from the six bands 40a to 40f in step S102 as the band for shooting in the shooting mode acquired in step S101 (step S103).

[0160] Then, the decision function 378 controls the reconstruction processing function 373 to perform reconstruction processing on the raw data representing the X-ray photon count results of the energy bands determined in step S103 (step S110). Through the control of step S110, the reconstruction processing function 373 performs reconstruction processing on the raw data representing the X-ray photon count results of the energy bands determined in step S103, from the raw data representing the X-ray photon count results of each of the six energy bands 40a to 40f, reconstructing the CT image data. Then, the decision function 378 ends the fourth energy band determination processing.

[0161] Specific examples will be given to illustrate the processing of step S110. For instance, in step S110, the decision function 378 first determines, based on the acquired imaging mode, conditions (second conditions) related to the energy bands associated with the data used in the reconstruction process from the data collected from the X-ray detector 13. These second conditions, like the first conditions, include the range of each energy band, the number of energy bands, and merging information.

[0162] For example, if band 40b is determined in step S110, then in step S110, the determination function 378 determines a second condition indicating that the band range is greater than or equal to energy value 41b and less than energy value 41c, and that the number of bands is "1". Furthermore, the merging information included in this second condition includes information indicating that merging is not performed. In step S110, the determination function 378 sends the determined second condition to the reconstruction processing function 373.

[0163] Upon receiving the second condition, the reconstruction processing function 373 performs reconstruction processing on the original data of the energy bands that match the second condition, from the original data representing the count results of X-ray photons for each of the six energy bands 40a to 40f. The reconstruction processing function 373 is an example of a reconstruction processing unit.

[0164] Next, the case where the energy table 35b is stored in the memory 35 will be described. The process of the fifth band determination process performed by the X-ray CT apparatus 1 using the energy table 35b will be described. The fifth band determination process is a process used to determine the bands associated with the original data that are the object of the reconstruction process based on the reconstruction processing function 373. Figure 19 This is a flowchart illustrating an example of the fifth band determination process performed by the X-ray CT apparatus 1 of the third embodiment.

[0165] like Figure 19 As shown, the acquisition function 377 and the determination function 378 perform the steps S201 to S203 of the second band determination process in the same way. For example, the acquisition function 377 acquires information indicating the type of medical device used during imaging (step S201), and the determination function 378 acquires the optimal band corresponding to the type of medical device shown in the information acquired in step S201 from the energy table 35b (step S202). Then, the determination function 378 determines the band corresponding to the band acquired from the six bands 40a to 40f in step S202 as the band for imaging using the type of medical device shown in the information acquired in step S201 (step S203).

[0166] Then, the decision function 378 controls the reconstruction processing function 373 to perform reconstruction processing (step S210) on the raw data representing the X-ray photon count results of the band determined in step S203. Then, the decision function 378 ends the fifth band determination process.

[0167] A specific example will be given to illustrate the processing of step S210. For instance, in step S210, the decision function 378 first determines the second condition based on the type of medical device shown in the acquired information. Then, in step S210, the decision function 378 sends the determined second condition to the reconstruction processing function 373.

[0168] Next, the case where the energy table 35c is stored in the memory 35 will be described. The process of the sixth band determination process performed by the X-ray CT apparatus 1 using the energy table 35c will be described. The sixth band determination process is a process used to determine the bands associated with the original data that are the object of the reconstruction process performed based on the reconstruction processing function 373. Figure 20 This is a flowchart illustrating an example of the sixth band determination process performed by the X-ray CT apparatus 1 of the third embodiment.

[0169] like Figure 20 As shown, the acquisition function 377 and the determination function 378 perform the steps S301 to S303 of the third band determination process in the same way. For example, the acquisition function 377 acquires information indicating the shooting location (step S301), and the determination function 378 acquires the optimal band corresponding to the shooting location shown in the information acquired in step S301 from the energy table 35c (step S302). Then, the determination function 378 determines the band corresponding to the band acquired from the six bands 40a to 40f in step S302 as the band for shooting the shooting location shown in the information acquired in step S301 (step S303).

[0170] Then, the decision function 378 controls the reconstruction processing function 373 to perform reconstruction processing (step S310) on the raw data representing the X-ray photon count results of the band determined in step S303. Then, the decision function 378 ends the sixth band determination process.

[0171] A specific example will be given to illustrate the processing of step S310. For instance, in step S310, the decision function 378 first determines a second condition based on the shooting location shown by the acquired information. Then, in step S310, the decision function 378 sends the determined second condition to the reconstruction processing function 373.

[0172] The X-ray CT apparatus 1 according to the third embodiment has been described above. According to the third embodiment, since an effective energy band corresponding to the imaging mode, the type of medical device, or the imaging site is determined, image data with value for effective clinical examination can be generated.

[0173] Furthermore, the X-ray CT apparatus 1 of the third embodiment automatically optimizes the energy band based on the imaging mode, the type of medical device, or the imaging site. Therefore, according to the third embodiment, the optimal energy band can be automatically determined based on the imaging mode, the type of medical device, or the imaging site. Thus, according to the third embodiment, compared to the case where the user manually sets the energy band, the burden on the user during setup or imaging can be reduced. In addition, improvements to the workflow can be anticipated. Furthermore, according to the third embodiment, since the energy band is automatically determined, the user can undergo a photon-count CT examination without realizing it is a photon-count CT scan, experiencing the same sensation as a regular CT scan without setting the energy band.

[0174] (Fourth Implementation)

[0175] When multiple energy bands are used for imaging, the X-ray photon count results sometimes differ significantly for each energy band. In such cases, even when the original data for all energy bands are reconstructed under the same reconstruction conditions, the noise level of the X-ray CT image data obtained for each energy band sometimes differs significantly between the multiple energy bands. As a result, there are cases where the noise level of the image displayed on the monitor 32 differs significantly for each energy band. Therefore, the X-ray CT apparatus 1 can also change the reconstruction conditions for each energy band to make the noise level of the image more uniform across the multiple energy bands. Therefore, such an embodiment will be described as the fourth embodiment. Furthermore, in the description of the fourth embodiment, the differences from the first embodiment, variations of the first embodiment, the second embodiment, and the third embodiment will be mainly described, and the description of structures that are the same as those in the first embodiment, variations of the first embodiment, the second embodiment, and the third embodiment will sometimes be omitted.

[0176] The following describes the case in which the X-ray CT apparatus 1 determines the reconstruction conditions for each of the plurality of energy bands determined by the determination function 378 in any of the first embodiment, a variation of the first embodiment, the second embodiment, and the third embodiment. However, the X-ray CT apparatus 1 may also determine the reconstruction conditions for each of the plurality of energy bands set by the user via the input interface 31.

[0177] The flow of the reconstruction condition determination process performed by the X-ray CT apparatus 1 according to the fourth embodiment will be described. The reconstruction condition determination process is a process used to determine the optimal reconstruction conditions for each of the multiple energy bands. Figure 21 This is a flowchart illustrating an example of the reconstruction condition determination process performed by the X-ray CT apparatus 1 according to the fourth embodiment.

[0178] like Figure 21 As shown, the decision function 378 selects one unselected band from multiple bands (step S401). Then, the decision function 378 determines the optimal reconstruction condition corresponding to the selected band from a plurality of pre-determined reconstruction conditions (step S402).

[0179] The specific order in which the determination function 378 determines the reconstruction conditions in step S402 will be explained. First, the processing order of step S402 in the case where the raw data for the selected band has not been collected will be explained. Here, the X-ray photon count result for the selected band is predicted in advance, and the predicted count result is stored in memory 35. The determination function 378 retrieves the predicted count result from memory 35 and determines the noise suppression reconstruction conditions based on the X-ray photon count result shown in the predicted count result. For example, the determination function 378 determines the reconstruction conditions in such a way that the noise level of the X-ray CT image data is constant or approximately constant across all bands. To illustrate with a specific example, the determination function 378 selects the reconstruction condition that the fewer the X-ray photon count result, the higher the degree of noise suppression.

[0180] Next, the processing sequence of step S402 will be explained when raw data of the selected band has been collected. The decision function 378 determines the reconstruction conditions for noise suppression based on the X-ray photon count results shown in the collected raw data. For example, similar to the case where no raw data has been collected, the decision function 378 determines the reconstruction conditions in a manner that keeps the noise level of the X-ray CT image data constant. For example, the decision function 378 selects the reconstruction condition that the lower the X-ray photon count result, the higher the degree of noise suppression.

[0181] Then, decision function 378 determines whether there is an unselected band among the multiple bands (step S403). If there is an unselected band (step S403: Yes), decision function 378 returns to step S401 and executes the processing after step S401 again. In this way, decision function 378 performs the processing of step S402 on all bands, thereby determining the reconstruction conditions corresponding to each of the bands.

[0182] In addition, if there are no unselected bands (step S403: No), the determination function 378 controls the reconstruction processing function 373 to reconstruct the raw data representing the count results of X-ray photons for each of the multiple bands under reconstruction conditions determined for each band (step S404).

[0183] Through the control of step S404, the reconstruction processing function 373 reconstructs the X-ray CT image data by performing reconstruction processing on the original data representing the count results of X-ray photons for each of the multiple energy bands under reconstruction conditions determined for each energy band. Thus, the X-ray CT image data is reconstructed for each energy band. In the fourth embodiment, the noise level of the reconstructed X-ray CT image data for each energy band becomes uniform. Therefore, according to the fourth embodiment, it is possible to suppress the situation where the noise level of the image displayed on the display 32 varies significantly for each energy band.

[0184] Here, for example, if the first reconstruction condition and the second reconstruction condition are different, the reconstruction process performed under the first reconstruction condition and the reconstruction process performed under the second reconstruction condition are considered to be different reconstruction processes. Therefore, in the fourth embodiment, the reconstruction processing function 373 performs different reconstruction processes based on the multiple energy bands of the data collected from the X-ray detector 13.

[0185] (Fifth Implementation)

[0186] When the X-ray CT apparatus 1 cannot store the original data of the collection band in the memory 35 due to the limited free capacity of the memory 35, the collection band can be reduced. Therefore, this embodiment will be described as the fifth embodiment. Furthermore, in the description of the fifth embodiment, the differences from the first embodiment, variations of the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment will be mainly described, and the description of structures that are the same as those in the first embodiment, variations of the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment will sometimes be omitted.

[0187] Figure 22 This diagram illustrates an example of the processing performed by the X-ray CT apparatus 1 according to the fifth embodiment. For example, Figure 22 The processing in steps S501 to S503 shown is in Figure 5 The first bandgap determination process shown is executed between steps S103 and S104. Alternatively, the processing of steps S501 to S503 can also be performed... Figure 15 The second band determination process shown is executed between steps S203 and S204. Alternatively, the processing of steps S501 to S503 can also be performed... Figure 17The third band determination process shown is executed between steps S303 and S304. Alternatively, the processing of steps S501 to S503 can also be performed... Figure 18 The fourth band determination process shown is executed between steps S103 and S110. Alternatively, the processing of steps S501 to S503 can also be performed... Figure 19 The fifth band determination process shown is executed between steps S203 and S210. Alternatively, the processing of steps S501 to S503 can also be performed... Figure 20 The sixth band determination process shown is executed between steps S303 and S310.

[0188] exist Figure 22 In the preceding step (step S103, S203, or S303) of step S501 shown, the band structure is determined by determination function 378. Then, as... Figure 22 As shown, the determination function 378 obtains the free capacity of the memory 35 (step S501).

[0189] Then, if the determination function 378 has collected projection data using the determined bandgap, it determines whether the original data can be stored in the memory 35 (step S502). A specific example of the determination process in step S502 will be explained. For example, in step S502, if the determination function 378 has collected projection data using the determined bandgap, it estimates the data size of the original data generated by the preprocessing function 372. Then, the determination function 378 compares the estimated data size of the original data with the free capacity of the memory 35. If the estimated data size of the original data is larger than the free capacity of the memory 35, it determines that the original data cannot be stored in the memory 35 (step S502: No). On the other hand, if the estimated data size of the original data is less than or equal to the free capacity of the memory 35, the determination function 378 determines that the original data can be stored in the memory 35 (step S502: Yes).

[0190] If the decision function 378 can store the original data in the memory 35 (step S502: yes), proceed to the next step (step S104, S204, S304, S110, S210 or S310).

[0191] On the other hand, if the original data cannot be stored in the memory 35 (step S502: No), the decision function 378 reduces the number of energy bands determined in the previous step of step S501 (step S503). For example, the number of energy bands determined in the previous step of step S501... Figure 9The case of two energy bands 40b and 40c will be explained. In this case, in step S503, the decision function 378 reduces the two energy bands 40b and 40c to one energy band 40b.

[0192] Then, the decision function 378 proceeds to the next step (steps S104, S204, S304, S110, S210, or S310), and instead of using the energy band determined in the previous step S501, it uses the energy band with a reduced number of bands in step S503 for processing. That is, the decision function 378 determines the first condition or the second condition based on the free capacity of the memory 35.

[0193] The X-ray CT apparatus 1 according to the fifth embodiment has been described above. According to the fifth embodiment, by enabling band optimization, the data size of the raw data can be reduced, and the raw data can be stored in the memory 35.

[0194] Furthermore, in step S503, the decision function 378 may also display a screen on the display 32 for user confirmation before reducing the number of bands. Additionally, the decision function 378 may reduce the number of bands after obtaining user consent via the input interface 31 regarding the reduction of the number of bands.

[0195] (Sixth Implementation Method)

[0196] In order to generate image data corresponding to the user's needs, the X-ray CT apparatus 1 can also receive the desired reconstruction conditions from the user via the input interface 31. Therefore, this embodiment will be described as the sixth embodiment. Furthermore, in the description of the sixth embodiment, the differences from the first embodiment, variations of the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, and the fifth embodiment will be mainly described, and the description of structures that are the same as those in the first embodiment, variations of the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, and the fifth embodiment will sometimes be omitted.

[0197] Figure 23 This is a diagram illustrating an example of the data structure of the energy table 35d in the sixth embodiment. (See diagram for example.) Figure 23 As shown, there are multiple records in energy table 35d, which contain items for "reconstruction conditions" and "energy band".

[0198] The "Refactoring Conditions" section contains information indicating the refactoring conditions. For example, such as... Figure 23As shown, the first record's "Refactoring Conditions" section includes the refactoring condition "AA". Additionally, the second record's "Refactoring Conditions" section includes the refactoring condition "BB". Thus, the "Refactoring Conditions" section contains information related to the refactoring conditions.

[0199] The "Band" section lists the optimal band corresponding to the reconfiguration conditions shown in the "Reconfiguration Conditions" section. For example, as... Figure 23 As shown, the first recorded "band" item has the optimal band "energy value 41b~41c" corresponding to the reconstruction condition "AA". This band "energy value 41b~41c" represents a band with an energy value of 41b or higher and less than 41c.

[0200] Additionally, the second record's "Band" section lists the optimal band with "energy values ​​41c to 41d" corresponding to the reconstruction condition "BB". This "energy value 41c to 41d" refers to bands with energy values ​​above 41c and below 41d.

[0201] Next, the process of the seventh band determination process performed by the X-ray CT apparatus 1 in the sixth embodiment will be described. The seventh band determination process is used to determine the band used by the X-ray detector 13 when generating the digital data described above. Figure 24 This is a flowchart illustrating an example of the seventh band determination process performed by the X-ray CT apparatus 1 according to the sixth embodiment.

[0202] Here, in the sixth embodiment, during execution Figure 24 Before the seventh band determination process shown, one or more desired reconstruction conditions are received from the user via input interface 31. For example, the user inputs one or more desired reconstruction conditions via input interface 31 to generate image data representing an image that matches the user's preferences. Furthermore, the desired reconstruction conditions received by input interface 31 are an example of input information related to reconstruction conditions. Additionally, input interface 31 is an example of a receiving unit.

[0203] like Figure 24 As shown, the decision function 378 selects one unselected reconstruction condition from one or more reconstruction conditions accepted by the input interface 31 (step S601).

[0204] Then, the decision function 378 obtains the optimal energy band corresponding to the reconstruction condition selected in step S601 from the energy table 35d (step S602).

[0205] Then, the determination function 378 determines the band corresponding to the band obtained from the six bands 40a to 40f in step S602 as the band to be used when collecting projection data (step S603).

[0206] Then, the decision function 378 determines whether there is an unselected reconstruction condition among the more than one reconstruction condition accepted by the input interface 31 (step S604). If there is an unselected reconstruction condition (step S604: Yes), the decision function 378 returns to step S601 and performs the processing after step S601 again. In this way, the decision function 378 determines the optimal energy band corresponding to each of the reconstruction conditions by processing all the reconstruction conditions in steps S602 and S603.

[0207] Furthermore, if no unselected reconstruction conditions are found (step S604: No), the determination function 378 causes the X-ray detector 13 to set the energy band determined according to each reconstruction condition as the energy band used when collecting projection data (step S605). That is, in step S605, the determination function 378 determines the first condition related to the energy band of the data collected from the X-ray detector 13 based on the desired reconstruction conditions. Then, the determination function 378 ends the seventh energy band determination process.

[0208] The X-ray CT apparatus 1 according to the sixth embodiment has been described above. According to the sixth embodiment, by optimizing the energy band according to the user's desired reconstruction conditions, it is possible to suppress the increase in the data size of the digital data output from the X-ray detector 13. Furthermore, it is possible to suppress the increase in the data size of the raw data stored in the memory 35 of the control console 30.

[0209] Furthermore, according to the sixth embodiment, an effective energy band corresponding to the desired reconstruction conditions is determined, thereby enabling the generation of image data with value for effective clinical examination.

[0210] Furthermore, the X-ray CT apparatus 1 of the sixth embodiment automatically optimizes the energy band according to the desired reconstruction conditions. Therefore, according to the sixth embodiment, the optimal energy band can be automatically determined based on the desired reconstruction conditions. Thus, according to the sixth embodiment, compared to the case where the user manually sets the energy band, the burden on the user during setup or imaging can be reduced. Furthermore, improvements in workflow can be anticipated. Additionally, according to the sixth embodiment, since the energy band is automatically set, the user can undergo a photon-count CT examination without realizing it is a photon-count CT scan, experiencing the same sensation as a regular CT scan without setting the energy band.

[0211] Furthermore, in the first embodiment, variations of the first embodiment, the second embodiment, and the sixth embodiment, the case where the X-ray detector 13 cannot be set to an arbitrary energy band was described. However, in the first embodiment, variations of the first embodiment, the second embodiment, and the sixth embodiment, the X-ray detector 13 can also be set to an arbitrary energy band. In this case, the determination function 378 can enable the X-ray detector 13 to be set to an arbitrary energy band.

[0212] The term "processor" used in the above description refers to circuits such as CPU (Central Processing Unit), GPU (Graphics Processing Unit), Application Specific Integrated Circuit (ASIC), or programmable logic device (e.g., Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), or Field Programmable Gate Array (FPGA)). The processor performs its functions by reading and executing a program stored in memory 35. Alternatively, the program can be loaded directly into the processor's circuitry instead of being stored in memory 35. In this case, the processor performs its functions by reading and executing the program loaded into the circuitry. Furthermore, the processors in this embodiment are not limited to being configured as a single circuit; multiple independent circuits can be combined to form a single processor to perform its functions.

[0213] According to at least one embodiment or at least one variation of the X-ray CT apparatus 1 described above, the optimal energy band can be determined based on the imaging mode, the body part to be imaged, or the type of medical equipment.

[0214] Several embodiments have been described, but these embodiments are given by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, 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 or spirit of the invention, as well as in the scope of the invention as described in the claims and its equivalents.

[0215] Regarding the above-described embodiments, the following notes are disclosed as one aspect and optional feature of the invention.

[0216] (Postscript 1)

[0217] A photon counting CT device, comprising:

[0218] A photon counting detector detects X-ray photons and obtains energy information;

[0219] The acquisition unit acquires at least one of the following: information related to the shooting mode, information related to the body part being photographed, and information related to the medical equipment; and

[0220] The decision unit, based on the information obtained by the acquisition unit, determines at least one of a first condition and a second condition, wherein the first condition is related to the energy band of the data collected from the photon counting detector, and the second condition is related to the energy band of the data used in the reconstruction process, wherein the data used in the reconstruction process is data from the data collected from the photon counting detector.

[0221] (Postscript 2)

[0222] Alternatively, the photon counting detector may acquire the energy information of the band that matches the first condition determined by the decision unit.

[0223] (Note 3)

[0224] Alternatively, it may also include a reconstruction processing unit that performs the reconstruction processing on the energy band data in the data collected by the photon counting detector that matches the second condition determined by the decision unit, in order to reconstruct the X-ray CT image data.

[0225] (Postscript 4)

[0226] Alternatively, it may also include a storage unit for storing data collected from the photon counting detector. Alternatively, the decision unit may further determine at least one of the first or second conditions based on the free capacity of the storage unit.

[0227] (Note 5)

[0228] Alternatively, the photon counting detector may be configured to match the first condition and obtain the energy information of the configured energy band.

[0229] (Note 6)

[0230] Alternatively, the photon counting detector can merge multiple energy bands to match the first condition and obtain the energy information of the set energy band.

[0231] (Note 7)

[0232] A photon counting CT device, comprising:

[0233] A photon counting detector detects X-ray photons and obtains energy information; and

[0234] The reconstruction processing unit performs different reconstruction processes based on multiple energy bands of the data collected from the photon counting detector.

[0235] (Postscript 8)

[0236] A photon counting CT device, comprising:

[0237] A photon counting detector detects X-ray photons and obtains energy information;

[0238] The receiving section accepts input information related to the desired reconstruction conditions; and

[0239] The decision unit, based on the input information, determines the conditions related to the energy bands of the data collected from the photon counting detector.

Claims

1. A photon counting CT device, comprising: A photon counting detector detects X-ray photons and obtains energy information; The storage unit stores the data collected from the photon counting detector; The acquisition unit acquires at least one of the following: information related to the shooting mode, information related to the body part being photographed, and information related to the medical equipment; and The decision unit, based on information obtained by the acquisition unit, determines at least one of a first condition and a second condition. The first condition is related to the energy band of the data collected from the photon counting detector, and the second condition is related to the energy band of the data used in the reconstruction process, wherein the data used in the reconstruction process is data collected from the photon counting detector. The decision unit further determines at least one of the first condition or the second condition based on the free capacity of the storage unit.

2. The photon counting CT device according to claim 1, wherein, The photon counting detector acquires the energy information of the energy band that matches the first condition determined by the decision unit.

3. The photon counting CT device according to claim 1, wherein, It also includes a reconstruction processing unit that performs the reconstruction processing on the energy band data in the data collected by the photon counting detector that matches the second condition determined by the decision unit, in order to reconstruct the X-ray CT image data.

4. The photon counting CT device according to claim 2, wherein, The photon counting detector sets an energy band that matches the first condition and obtains the energy information of the set energy band.

5. The photon counting CT device according to claim 4, wherein, The photon counting detector merges multiple energy bands to set an energy band that matches the first condition and obtains the energy information of the set energy band.

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