JP6297336B2 - Image processing device - Google Patents

Description

Embodiments of the present invention relates to an image processing equipment.

  2. Description of the Related Art Today, a photon counting CT apparatus (CT) using a photon counting detector is known. Unlike the integration type detector, the photon counting type detector outputs a signal capable of individually counting X-ray photons transmitted through the subject. Therefore, the photon counting CT apparatus can reconstruct an X-ray CT image having a high signal-to-noise ratio (S / N ratio).

  The signal output from the photon counting detector can be used for measuring (discriminating) the energy of X-ray photons. Therefore, in the photon counting CT apparatus, projection data collected by exposing one kind of tube voltage X-rays can be divided into a plurality of energy components and imaged.

  Here, a conventional X-ray CT apparatus provided with a photon counting CT apparatus and an integral detector obtains an X-ray CT image of a desired site by increasing the contrast with a contrast agent.

  However, it has been difficult for a conventional X-ray CT apparatus provided with an integral type detector to accurately identify the distribution of a contrast medium from an X-ray CT image captured using one type of contrast medium.

  In the case of a so-called dual X-ray CT apparatus, X-ray CT images corresponding to two types of X-ray sources having different X-ray energies are acquired. Then, the dual X-ray CT apparatus uses a weighting process, a subtraction process, an addition process, and the like to discriminate X-ray CT images of regions where contrast agents are accumulated from each X-ray CT image. However, in the case of a dual X-ray CT apparatus, although X-ray CT images corresponding to two types of X-ray sources are used, each X-ray CT image was imaged using the same one type of contrast agent. Is. For this reason, also in the case of a dual X-ray CT apparatus, it is difficult to accurately specify the distribution of the contrast agent as described above.

JP 2001-209142 A JP 2010-025711 A JP 2004-066463 A

An object of the present invention is to provide a distribution of the contrast agent, to provide a more accurately identifiable image processing equipment.

According to the embodiment, acquisition unit, and the 1X-ray CT image in the first energy, rather greater than the first energy, and, during the fifth energy K-absorption edge of the first imaging composition of the first energy a first 2X-ray CT image in the second energy in the second 3X-ray CT image in the second energy than the size of the third energy, rather greater than the third energy, and, K absorption edge of the second contrast compositions A fourth X-ray CT image at a fourth energy between the sixth energy and the third energy is acquired, and the detection unit is configured to obtain a first difference image between the first X-ray CT image and the second X-ray CT image, and A second difference image between the third X-ray CT image and the fourth X-ray CT image is detected. And an extraction part extracts the duplication image which shows the site | part where a 1st difference image and a 2nd difference image overlap .

FIG. 1 is a diagram illustrating a configuration of a photon counting CT apparatus according to an embodiment. FIG. 2 is a plan view of a detector provided in the photon counting CT apparatus of the embodiment. FIG. 3 is a hardware configuration diagram of the console device of the photon counting CT apparatus according to the embodiment. FIG. 4 is a functional block diagram of a reconfiguration unit provided in the console device of the photon counting CT apparatus of the embodiment. FIG. 5 is a flowchart illustrating a flow of an imaging operation of the photon counting CT apparatus according to the embodiment. FIG. 6 is a graph showing the K absorption edges of two types of contrast agents. FIG. 7 is a diagram illustrating an example of X-ray CT images corresponding to the K absorption edges of two types of contrast agents in the photon counting CT apparatus of the embodiment. FIG. 8 is a diagram illustrating another example of an X-ray CT image corresponding to the K absorption ends of two types of contrast agents in the photon counting CT apparatus of the embodiment.

  Hereinafter, a photon counting CT apparatus according to an embodiment to which an image processing apparatus and a contrast composition are applied will be described in detail with reference to the drawings.

  The photon counting CT apparatus reconstructs X-ray CT image data having a high S / N ratio by counting X-ray photons transmitted through a subject using a photon counting type detector. Individual X-ray photons generated from the X-ray source have different energies. The photon counting CT apparatus obtains information on the energy component of X-rays transmitted through the subject by measuring the energy value of the X-ray photons. A photon counting CT apparatus images projection data acquired by driving an X-ray tube with one type of tube voltage into a plurality of energy components.

  FIG. 1 shows the configuration of the photon counting CT apparatus of the embodiment. As shown in FIG. 1, the photon counting CT apparatus includes a gantry device 10, a bed device 20, and a console device 30.

  The gantry device 10 includes an irradiation control unit 11, an X-ray generation device 12, a detector 13, a collection unit 14, a rotating frame 15, and a drive unit 16. The gantry device 10 exposes the subject P to X-rays and counts the X-rays transmitted through the subject P. Note that some or all of the units 11 to 16 of the gantry device 10 may be configured by software.

  The rotating frame 15 supports the X-ray generator 12 and the detector 13 so as to face each other with the subject P interposed therebetween. The rotating frame 15 is an annular frame that is rotated at a high speed in a circular orbit around the subject P by a driving unit 16 described later.

  The X-ray generator 12 includes an X-ray tube 12a, a wedge 12b, and a collimator 12c. The X-ray generator 12 is an apparatus that generates X-rays and exposes the subject P. The X-ray tube 12a is a vacuum tube that irradiates the subject P with X-rays by a high voltage supplied from an X-ray generator 12 described later. The X-ray tube 12 a emits an X-ray beam to the subject P while rotating according to the rotation of the rotary frame 15. The X-ray tube 12a generates an X-ray beam that spreads with a fan angle and a cone angle.

  The wedge 12b is an X-ray filter for adjusting the X-ray dose of X-rays emitted from the X-ray tube 12a. Specifically, the wedge 12b transmits the X-rays exposed from the X-ray tube 12a so that the X-rays exposed from the X-ray tube 12a to the subject P have a predetermined distribution. It is a filter that attenuates.

  For example, the wedge 12b is a filter obtained by processing aluminum so as to have a predetermined target angle or a predetermined thickness. The wedge is also called a wedge filter or a bow-tie filter. The collimator 12c is a slit for narrowing the X-ray exposure range in which the X-ray dose is adjusted by the wedge 12b under the control of the irradiation control unit 11 described later.

  The irradiation control unit 11 is a device that supplies a high voltage to the X-ray tube 12 a as a high voltage generation unit, and the X-ray tube 12 a generates X-rays using the high voltage supplied from the irradiation control unit 11. . The irradiation control unit 11 adjusts the X-ray dose exposed to the subject P by adjusting the tube voltage and tube current supplied to the X-ray tube 12a. The irradiation control unit 11 adjusts the X-ray exposure range (fan angle and cone angle) by adjusting the aperture of the collimator 12c.

  The drive unit 16 rotates the rotary frame 15 to rotate the X-ray generator 12 and the detector 13 on a circular orbit around the subject P. Each time the X-ray photon is incident, the detector 13 outputs a signal capable of measuring the energy value of the X-ray photon. The X-ray photons are X-ray photons that have been exposed from the X-ray tube 12a and transmitted through the subject P, for example. The detector 13 has a plurality of detection elements that output one pulse of an electrical signal (analog signal) each time an X-ray photon enters. By counting the number of electrical signals (pulses), the number of X-ray photons incident on each detection element can be counted. Moreover, the energy value of the X-ray photon which caused the output of the said signal can be measured by performing arithmetic processing of this signal.

  The detection element of the detector 13 is a cadmium telluride (CdTe) based semiconductor element, for example. In this case, the detector 13 becomes a “direct conversion type detector” that directly converts an incident X-ray photon into an electric signal.

  Further, the detection element of the detector 13 may be constituted by, for example, a scintillator and an optical sensor such as a photomultiplier tube. In this case, the detector 13 converts the incident X-ray photons into visible light (scintillator light) once with a scintillator, and converts the scintillator light into an electrical signal with an optical sensor such as a photomultiplier tube. Detector ".

  FIG. 2 shows an example of the detector 13. In the detector 13, detector elements 40 made of cadmium telluride are arranged in N rows in the channel direction (Y-axis direction in FIG. 1) and M rows in the body axis direction (Z-axis direction in FIG. 1). It is a surface detector. When the photon is incident, the detection element 40 outputs an electric signal of one pulse. By discriminating the individual pulses output from the detection element 40, the number of X-ray photons incident on the detection element 40 can be counted. Moreover, the energy value of the counted X-ray photon can be measured by performing arithmetic processing based on the intensity of the pulse.

  Although not shown, an amplifier is provided for each of the plurality of detection elements 40 at the subsequent stage of the detector 13, and the amplifier amplifies the electrical signal output from the detection element 40 at the previous stage, and the result shown in FIG. To the collecting unit 14 shown.

  The collection unit 14 collects count information that is a result of the count process using the output signal of the detector 13. That is, the collection unit 14 discriminates individual signals output from the detector 13 and collects count information. The count information is information collected from individual signals output from the detector 13 (a plurality of detection elements 40) each time an X-ray photon that has been exposed from the X-ray tube 12a and transmitted through the subject P enters. Specifically, the count information is information in which a count value of X-ray photons incident on the detector 13 (a plurality of detection elements 40) and an energy value are associated with each other. The collection unit 14 transmits the collected count information to the console device 30.

  That is, the collection unit 14 uses the incident position (detection position) of the X-ray photon obtained by discriminating and counting each pulse output from the detection element 40, the count value, and the energy value of the X-ray photon as count information in advance. Collect at regular intervals. For example, the collection unit 14 sets the position of the detection element 40 that has output the pulse (electric signal) used for counting as the incident position. Moreover, the collection part 14 measures the energy value of a X-ray photon by performing predetermined | prescribed arithmetic processing with respect to an electric signal.

  Next, the couch device 20 shown in FIG. 1 is a device on which the subject P is placed, and includes a couchtop 22 and a couch driving device 21. The couchtop 22 is a plate on which the subject P is placed, and the couch driving device 21 moves the couchtop 22 in the rotary frame 15 by moving the couchtop 22 in the Z-axis direction.

  For example, the gantry device 10 performs a helical scan that rotates the rotating frame 15 while moving the top plate 22 to scan the subject P in a spiral shape. Alternatively, the gantry device 10 performs a conventional scan in which the subject P is scanned in a circular orbit by rotating the rotating frame 15 while moving the top plate 22 while the position of the subject P is fixed. Alternatively, the gantry device 10 executes a step-and-shoot method in which a conventional scan is performed in a plurality of scan areas by moving the position of the top plate 22 at regular intervals.

  Next, the console device 30 includes an input unit 31, a display unit 32, a scan control unit 33, a preprocessing unit 34, a first storage unit 35, a reconstruction unit 36, a second storage unit 37, And a control unit 38. The console device 30 accepts the operation of the X-ray CT apparatus by the operator, and reconstructs the X-ray CT image using the count information collected by the gantry device 10.

  The input unit 31 includes a mouse, a keyboard, and the like used by an operator of the X-ray CT apparatus for inputting various instructions and various settings, and transfers instructions and setting information received from the operator to the control unit 38. For example, the input unit 31 receives imaging conditions for X-ray CT image data, reconstruction conditions for reconstructing X-ray CT image data, image processing conditions for X-ray CT image data, and the like from the operator.

  The display unit 32 is a monitor device referred to by the operator, displays X-ray CT image data under the control of the control unit 38, and also provides various instructions and various settings from the operator via the input unit 31. A GUI (Graphical User Interface) for accepting and the like is displayed.

  The scan control unit 33 controls the operation of the irradiation control unit 11, the drive unit 16, the collection unit 14, and the couch drive device 21 under the control of the control unit 38, thereby collecting the count information in the gantry device 10. Control.

  The preprocessing unit 34 generates projection data by performing correction processing such as logarithmic conversion processing, offset correction, sensitivity correction, and beam hardening correction on the count information transmitted from the collection unit 14.

  The first storage unit 35 stores the projection data generated by the preprocessing unit 34. That is, the first storage unit 35 stores projection data (corrected count information) for reconstructing X-ray CT image data.

  The reconstruction unit 36 reconstructs X-ray CT image data using the projection data stored in the first storage unit 35. As the reconstruction method, there are various methods, for example, back projection processing. Further, as the back projection process, for example, a back projection process by an FBP (Filtered Back Projection) method can be cited. The reconstruction unit 36 generates image data by performing various types of image processing on the X-ray CT image data. The reconstruction unit 36 stores the reconstructed X-ray CT image data and image data generated by various image processes in the second storage unit 37.

  Here, the projection data generated from the counting information obtained by photon counting CT includes energy information of X-rays transmitted through the subject P. Therefore, the reconstruction unit 36 can reconstruct X-ray CT image data of a specific energy component, for example. The reconstruction unit 36 can reconstruct X-ray CT image data of each of a plurality of energy components, for example.

  For example, the reconstruction unit 36 assigns a color tone corresponding to the energy component to each pixel of the X-ray CT image data of each energy component, and generates a plurality of X-ray CT image data color-coded according to the energy component. Furthermore, image data in which the plurality of X-ray CT image data are superimposed can be generated.

  The control unit 38 performs overall control of the X-ray CT apparatus by controlling operations of the gantry device 10, the couch device 20, and the console device 30. Specifically, the control unit 38 controls the CT scan performed by the gantry device 10 by controlling the scan control unit 33. Further, the control unit 38 controls the image reconstructing process and the image generating process in the console device 30 by controlling the preprocessing unit 34 and the reconstruction unit 36. In addition, the control unit 38 controls display of various image data stored in the second storage unit 37 on the display unit 32.

  Such a console device 30 may have a hardware configuration shown in FIG. 3 as an example. In the example illustrated in FIG. 3, the console device 30 includes a CPU 50, a ROM 51, a RAM 52, an HDD 53, an input / output I / F 54, a communication I / F 55, an input unit 31, and a display unit 32. ing. CPU is an abbreviation for “Central Processing Unit”. ROM is an abbreviation for “Read Only Memory”. RAM is an abbreviation for “Random Access Memory”. HDD is an abbreviation for “Hard Disk Drive”. I / F is an abbreviation for “Interface”.

  The CPU 50 to the communication I / F 55 are connected to each other via a bus line 56. The input unit 31 and the display unit 32 are connected to the CPU 50 and the like via the input / output I / F 54. The communication I / F 55 is connected to the gantry device 10. The CPU 50 corresponds to the scan control unit 33, the preprocessing unit 34, the reconstruction unit 36, or the control unit 38. The ROM 51, RAM 52, and HDD 53 correspond to the first storage unit 35 or the second storage unit 37.

  Next, FIG. 4 is a functional block diagram of the reconstruction unit 36. As illustrated in FIG. 4, the reconstruction unit 36 has functions of an acquisition unit 61, a detection unit 62, an extraction unit 63, and a superimposition unit 64. The acquisition unit 61 acquires an X-ray CT image captured by the gantry device 10.

  As will be described later, the acquisition unit 61 acquires an X-ray CT image obtained by imaging a subject to which a contrast composition containing a plurality of contrast agents for X-ray CT each having a different K absorption edge is administered. . That is, in the present embodiment, at least two types of contrast compositions are administered to the subject. For example, energy lower than the energy at the K absorption edge (fifth energy) of one type of contrast composition is set as the first energy, and energy larger than the energy at the K absorption edge is set as the second energy. The energy smaller than the energy at the K absorption edge (sixth energy) of the other type of contrast composition is defined as the third energy, and the energy larger than the energy at the K absorption edge is defined as the fourth energy.

  The acquisition unit 61 includes a first X-ray CT image at the first energy, a second X-ray CT image at a second energy greater than the first energy, and a third X-ray CT image at a third energy greater than or equal to the second energy. A fourth X-ray CT image at a fourth energy larger than the third energy is acquired.

  The detection unit 62 detects, from the X-ray CT images acquired by the acquisition unit 61, a difference image between a plurality of X-ray CT images corresponding to the X-ray energy regions before and after the K absorption edge of each X-ray CT contrast agent. To do. Specifically, the detection unit 62 detects a first difference image between the first X-ray CT image and the second X-ray CT image, and a second difference image between the third X-ray CT image and the fourth X-ray CT image. To do.

  The extraction unit 63 extracts an overlapping part image (overlapping image) indicating a part where a plurality of difference images obtained for each X-ray CT contrast agent overlap. That is, the extraction unit 63 forms a duplicate image by superimposing the first difference image and the second difference image.

  The superimposing unit 64 generates an X-ray CT image in which the overlapping part image is superimposed on the X-ray CT image of the subject including the part of the overlapping part image. That is, the superimposing unit 64 superimposes the overlapping image on at least one of the first to fourth X-ray CT images.

  In addition, the reconstruction unit 36 further includes a storage unit 65 that stores data of the fifth energy at the K absorption end of the first contrast agent and data of the sixth energy at the K absorption end of the second contrast agent. May be. Further, the first to fourth energy may be manually input as appropriate, or may be stored in the storage unit 65. The acquisition unit 61 to the storage unit 65 may be configured entirely by hardware. Moreover, you may comprise all or one part by software.

  Next, it is difficult to accurately specify the distribution of the contrast composition from the X-ray CT image using one type of contrast composition. Therefore, in the photon counting CT apparatus of this embodiment, a plurality of types (two types as an example) of contrast compositions are used, and from the X-ray CT images of the X-ray energy regions before and after the K absorption edge of each contrast composition, The distribution of the contrast composition can be accurately specified.

  First, in the photon counting CT apparatus of this embodiment, a mixed solution generated by mixing two types of contrast agents having K absorption edges in different X-ray energy regions can be used as a contrast composition. As the contrast agent, a contrast agent produced with heavy metals such as iodine, barium sulfate, and gadolinium can be used. This contrast agent mixed solution is injected into a desired site such as a blood vessel of a subject P or a specific organ. Thereby, the mixed solution of the contrast agent can be accumulated at a desired site of the subject P.

  Moreover, as the contrast composition, liposomes encapsulating a mixed solution generated by mixing two kinds of contrast agents having K absorption ends in different X-ray energy regions can be used. Such liposomes can be prepared, for example, using a static hydration method. Moreover, the liposome which has characteristics, such as photodegradability or radiolytic property, can be produced by changing the lipid to comprise.

  By using liposomes having characteristics such as photodegradability or radiodegradability, the following drug administration can be performed. That is, the above-mentioned multiple types of contrast agents and drugs are encapsulated in liposomes having photodegradable or radiodegradable properties and administered to a subject. After confirming the position of the contrast agent encapsulated in the liposome in the subject with the photon counting CT apparatus of the embodiment, the liposome is decomposed by irradiating the position where the liposome is present with specific light or radiation.

  For example, in a tumor tissue, vascular permeability is remarkably enhanced as compared with a normal tissue, and the lymph system is not developed. For this reason, macromolecules and fine particles in the blood are likely to flow out of the blood vessel and are difficult to be removed and accumulated. Such a characteristic is called an EPR (enhanced permeability and retention) effect. When liposomes are administered into a subject having a tumor tissue, many liposomes accumulate at sites where lesions are formed. For this reason, by using liposomes, a plurality of types of contrast agents can be delivered to a tumor site in a subject. When it is desired to deliver to a more limited place, it is possible to give an antibody that recognizes a specific tissue-specific protein or the like to the liposome surface. Moreover, a medicine can be accurately administered to a desired site by decomposing liposomes that have reached the desired site with specific light or radiation.

  In addition, as the contrast composition, an antibody to which one or a plurality of contrast agents are bound (label = label) can be used. For example, when two types of contrast agents are present, two types of antibodies may be prepared, an antibody labeled with one contrast agent and an antibody labeled with the other contrast agent. Alternatively, a plurality of contrast agents may be labeled on one antibody. The antibody reaches and accumulates at a desired site with high accuracy. For this reason, by using an antibody, it is possible to accurately identify and image a region to be imaged.

  Next, the flow of an X-ray CT image imaging operation using a plurality of contrast agents in the photon counting CT apparatus of the embodiment is shown in the flowchart of FIG. This imaging operation is mainly performed by the functions of the units 61 to 64 of the reconstruction unit 36 described with reference to FIG. The reconstruction unit 36 mounts the subject P, to which a plurality of types of contrast agents are administered by the above-described liposome or antibody, etc., on the bed apparatus 20 and can capture an X-ray CT image. The process of the flowchart of FIG. 5 is started.

  In step S1, the acquisition unit 61 shown in FIG. 4 acquires the projection data obtained from the collection unit 14 by controlling the imaging of the gantry device 10 as described above. Thereby, a process progresses to step S2.

  Here, the projection data generated from the counting information obtained by photon counting CT includes energy information of X-rays transmitted through the subject P. For this reason, the photon counting CT apparatus of the embodiment can reconstruct X-ray CT images of a plurality of X-ray energy components, respectively.

  Further, the contrast agent has a characteristic that it easily absorbs X-rays having specific energy. FIG. 6 is a diagram showing the relationship between the X-ray energy and the X-ray absorption coefficient. In FIG. 6, the waveform indicated by the alternate long and short dash line is a waveform indicating the relationship between the X-ray energy of the first contrast agent and the X-ray absorption coefficient. Moreover, in FIG. 6, the waveform shown with a dashed-two dotted line is a waveform which shows the relationship between the X-ray energy and X-ray absorption coefficient of a 2nd contrast agent. In FIG. 6, the waveform indicated by the solid line is a waveform indicating the relationship between the X-ray energy and the X-ray absorption coefficient of the contrast agent obtained by mixing the first contrast agent and the second contrast agent.

  As can be seen from FIG. 6, the X-ray absorption coefficient decreases as the X-ray energy increases, but the X-ray absorption coefficient increases abruptly (= the X-ray absorption rate increases). This part is called the absorption edge. The absorption edge is due to the action of X-rays and electrons in the nucleus of the substance. What originates in K-shell electrons is called the K absorption edge. In FIG. 6, in the case of a contrast medium in which two types of the first contrast medium and the second contrast medium indicated by the solid line waveform are mixed, the first K absorption edge EKA caused by the first contrast medium and the second contrast medium There are a total of two K absorption edges with the second K absorption edge EKB due to the above. There is a large difference in the X-ray absorption coefficient in the front and rear X-ray energy regions with the first K absorption edge EKA as a boundary.

  That is, the X-ray absorption coefficient in the X-ray energy region RKA1 corresponding to the area before the first K absorption edge EKA shows a low value. On the other hand, the X-ray absorption coefficient in the X-ray energy region RKA2 corresponding to after the first K absorption edge EKA shows a high value. For this reason, the difference in the X-ray absorption coefficient between the X-ray energy region RKA1 and the X-ray energy region RKA2 shows a large difference. Similarly, the X-ray absorption coefficient in the X-ray energy region RKB1 corresponding to the front of the second K absorption edge EKB shows a low value. On the other hand, the X-ray absorption coefficient in the X-ray energy region RKB2 corresponding to after the second K absorption edge EKB shows a high value. For this reason, the difference in the X-ray absorption coefficient between the X-ray energy region RKB1 and the X-ray energy region RKB2 shows a large difference.

  The photon counting CT apparatus of the embodiment uses such a difference in X-ray absorption coefficient before and after the K absorption edge. That is, in step S2, the detection unit 62 of the reconstruction unit 36 corresponds to the X-ray energy region RKA1 corresponding to the front of the first K absorption edge EKA shown in FIG. 6 from the projection data acquired by the acquisition unit 61. An X-ray CT image is reconstructed. Further, the detection unit 62 reconstructs an X-ray CT image corresponding to the X-ray energy region RKA2 corresponding to the portion after the first K absorption edge EKA shown in FIG. 6 from the projection data acquired by the acquisition unit 61.

  Similarly, the detection unit 62 reconstructs an X-ray CT image corresponding to the X-ray energy region RKB1 corresponding to the front of the second K absorption edge EKB shown in FIG. 6 from the projection data acquired by the acquisition unit 61. . Further, the detection unit 62 reconstructs an X-ray CT image corresponding to the X-ray energy region RKB2 corresponding to the second K absorption edge EKB shown in FIG. 6 from the projection data acquired by the acquisition unit 61.

  In step S2, the detection unit 62 indicates that the difference between the X-ray CT image corresponding to the X-ray energy region RKA1 and the X-ray CT image corresponding to the X-ray energy region RKA2 is greater than or equal to a predetermined threshold value. An X-ray CT image (difference image) of the part is formed. There is a high possibility that a location where such a large difference equal to or greater than the threshold value has occurred is a site where the first contrast agent is accumulated. A difference image of a portion where a large difference equal to or greater than the threshold value is generated is stored in the second storage unit 37 as an X-ray CT image of the first contrast agent accumulation site.

  Similarly, in step S2, the detection unit 62 determines that the difference between the X-ray CT image corresponding to the X-ray energy region RKB1 and the X-ray CT image corresponding to the X-ray energy region RKB2 is greater than or equal to a predetermined threshold value. A difference image of the indicated location is formed. There is a high possibility that a location where such a large difference exceeding the threshold is generated is an accumulation site of the second contrast agent. A difference image of a location where a large difference equal to or greater than the threshold value is stored in the second storage unit 37 as an X-ray CT image of the second contrast agent accumulation site.

  In step S3, the detection unit 62 determines whether or not difference images corresponding to the K absorption ends of all contrast agents have been formed. When the detection unit 62 determines that the difference image corresponding to the K absorption edge of all contrast agents is not formed (step S3: No), the process returns to step S2 to continue generating the difference image. . On the other hand, when it is determined that the difference image corresponding to the K absorption edge of all the contrast agents is formed (step S3: Yes), the detection unit 62 advances the process to step S4.

  In step S4, the extraction unit 63 superimposes each difference image corresponding to each contrast agent stored in the second storage unit 37, and extracts an X-ray CT image (overlapping region) where all the contrast agents are accumulated. Image). In step S5, the superimposing unit 64 superimposes the overlapping part image indicating the part where all the contrast agents are accumulated on the X-ray CT image of the subject P including the part of the overlapping part image. And the entire processing of the flowchart of FIG. Thereby, it is possible to obtain an X-ray CT image in which a target site, which is a site where the first contrast agent and the second contrast agent are accumulated, is clearly shown.

  This will be specifically described with reference to FIGS. 7 and 8 are X-ray CT images in a state in which the abdomen of the subject P is cut into circles. 7 is an X-ray CT image corresponding to the X-ray energy region RKA1. The figure which showed the code | symbol (b) of FIG. 7 is an X-ray CT image corresponding to X-ray energy area | region RKA2. Moreover, the figure which showed the code | symbol (a) of FIG. 8 is an X-ray CT image corresponding to X-ray energy area | region RKB1. The figure showing the code | symbol (b) of FIG. 8 is an X-ray CT image corresponding to X-ray energy area | region RKB2. 7 and 8, the symbol B is the spine, the symbol SP is the spleen, the symbol ST is the stomach, the symbol LI is the liver, the symbol RCA is the region where the contrast agent is accumulated, and the symbol AF is a false image (artifact). .

  In the case of the example illustrated in FIG. 7, the detection unit 62 of the reconstruction unit 36 includes an X-ray CT image corresponding to the X-ray energy region RKA1, which is an image of the diagram showing the code (a), and a code in step S2. Of the difference from the X-ray CT image corresponding to the X-ray energy region RKA2, which is the image in the diagram showing (b), a part having a difference equal to or greater than a predetermined threshold is detected. In the case of this example, a false image AF part in the liver LI and a first contrast agent accumulation part RCA are detected as a difference part between the X-ray CT images.

  In the case of the example shown in FIG. 8, in step S2, the detection unit 62 includes an X-ray CT image corresponding to the X-ray energy region RKB1, which is an image of the diagram showing the code (a), and a code (b). Among the differences from the X-ray CT image corresponding to the X-ray energy region RKB2, which is an image of the figure showing, a portion having a difference equal to or greater than a predetermined threshold is detected. In this example, the second contrast agent accumulation site RCA is detected as a difference site between the X-ray CT images.

  In step S4, the extraction unit 63 of the reconstruction unit 36 superimposes the X-ray CT image of the first contrast agent accumulation site RCA and the X-ray CT image of the second contrast agent accumulation site RCA. Then, the extraction unit 63 generates an X-ray CT image (superimposed region image) in which a region where both the first contrast agent and the second contrast agent are accumulated is extracted. Accordingly, the false image AF shown in FIG. 7A is not an image of a portion where the first contrast agent accumulation portion RCA and the second contrast agent accumulation portion RCA are superimposed and accumulated, It can remove from a superimposition site | part image. Then, the superimposing unit 64 of the reconstruction unit 36 extracts a superposed region obtained by extracting a region where both the first contrast agent and the second contrast agent are accumulated in the X-ray CT image of the subject P including the region of the overlapping region image. Superimpose the image. Thereby, it is possible to provide an X-ray CT image in which a target site that is a site where the first contrast agent and the second contrast agent are accumulated is clearly shown.

  As is clear from the above description, the photon counting CT apparatus according to the embodiment to which the image processing apparatus and the contrast composition are applied administers a plurality of contrast agent compositions to the subject P. A difference image that is a difference between the X-ray CT images corresponding to the X-ray energy regions before and after the K absorption edge of each contrast agent is generated. By superimposing the difference images of the respective contrast agents, an X-ray CT image (superimposed region image) of a region where all the contrast agents are present is generated. A part where all the contrast agents are accumulated indicates a target part with a high probability. In addition, by extracting the superimposed part image of the part where all the contrast agents exist, only the X-ray CT image of the target part can be accurately extracted. This means that the false image AF other than the X-ray CT image of the target part is removed. Therefore, by superimposing the overlapping part image on the X-ray CT image of the subject P including the part of the overlapping part image, a false image or the like is removed and an X-ray CT image in which the target part is clearly shown can be obtained. .

  In addition, the photon counting CT apparatus of the embodiment performs imaging of an X-ray CT image by administering a liposome encapsulating a plurality of contrast agents to the subject P. Liposomes tend to accumulate in tumor tissue. Furthermore, it is possible to accumulate in a specific tissue by applying an antibody that recognizes a specific tissue-specific protein or the like to the liposome surface. By these methods, it is possible to obtain an X-ray CT image in which the target site is very clarified.

  In addition, the photon counting CT apparatus of the embodiment is formed of a member having a characteristic of decomposing a liposome containing a plurality of contrast agents and a predetermined agent with specific light or radiation. Then, the X-ray CT image is taken by administration to the subject P, and the liposome accumulated at a desired site is irradiated with specific light or radiation to be decomposed. As a result, a clear X-ray CT image of the desired site can be obtained, and drug administration to the desired site can be performed.

  The photon counting CT apparatus of the embodiment produces two types of antibodies, for example, an antibody labeled with one contrast agent and an antibody labeled with the other contrast agent when two types of contrast agents exist. Then, it is administered to the subject P to obtain the above-mentioned X-ray CT image. Alternatively, a plurality of contrast agents are labeled on one antibody and administered to the subject P to obtain the above-mentioned X-ray CT image. The antibody reaches and accumulates at a desired site with high accuracy. For this reason, the X-ray CT image which specified the site | part used as imaging object more correctly can be obtained by using an antibody.

  The above-described embodiment is an example of a photon counting CT apparatus provided with the photon counting detector 13. In addition, an integral detector may be provided as the detector 13. In this case, four types of X-ray tubes for exposing the X-rays in the X-ray energy regions RKA1, RKA2, RKB1, and RKB2 before and after the K absorption ends EKA and EKB shown in FIG. Further, by exposing X-rays to the subject P to which the first contrast agent and the second contrast agent are administered with each X-ray tube, X corresponding to each X-ray energy region RKA1, RKA2, RKB1, RKB2 A line CT image is generated.

  Further, the difference between the X-ray CT images in the X-ray energy region RKA1 and the X-ray energy region RKA2 and the difference between the X-ray CT images in the X-ray energy region RKB1 and the X-ray energy region RKB2 are superimposed. Thereby, it is possible to obtain an X-ray CT image (superimposed region image) in which a region where both the first contrast agent and the second contrast agent are accumulated is extracted. Then, by superimposing the overlapping part image on the X-ray CT image of the subject P including the part of the overlapping part image, a false image or the like is removed and an X-ray CT image in which the target part is clearly shown can be obtained. .

  Although the embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 Stand apparatus 11 Irradiation control part 12 X-ray generator 13 Detector 14 Collection part 15 Rotating frame 16 Drive part 20 Bed apparatus 21 Bed drive apparatus 22 Top plate 30 Console apparatus 31 Input part 32 Display part 33 Scan control part 34 Preprocessing Unit 35 First storage unit 36 Image reconstruction unit 37 Second storage unit 38 Control unit 40 Detection element 50 CPU
51 ROM
52 RAM
53 HDD
54 I / O I / F
55 Communication I / F
61 Acquisition Unit 62 Detection Unit 63 Extraction Unit 64 Superimposition Unit 65 Storage Unit

Claims (3)

A first 1X-ray CT image in the first energy, the first energy than rather large, and, the 2X in the second energy fifth energy K-absorption edge of the first contrast compositions is between the first energy and line CT image, and the 3X-ray CT image in the third energy of said second energy more size, rather greater than the third energy, and, sixth energy K absorption edge of the second imaging composition wherein An acquisition unit for acquiring a fourth X-ray CT image at a fourth energy between the third energy ;
A detection unit for detecting a first difference image between the first X-ray CT image and the second X-ray CT image, and a second difference image between the third X-ray CT image and the fourth X-ray CT image;
An image processing apparatus comprising: an extraction unit that extracts an overlapping image indicating a portion where the first difference image and the second difference image overlap . Further have a storage unit for storing the data of the fifth energy data and the sixth energy,
The image processing apparatus according to claim 1. The image processing apparatus according to claim 1, further comprising: a superimposing unit that superimposes the overlapping image on at least one of the first to fourth X-ray CT images.

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