JP5269298B2 - X-ray diagnostic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray diagnostic apparatus supporting an operator in recognizing an image and improving the efficiency in the X-ray examination by additionally displaying image information, which cannot be easily displayed on an X-ray image though useful for the diagnosis in the interventional radiology (IVR), as a reference image with high contrast; and a method of processing data in the X-ray diagnostic apparatus. <P>SOLUTION: The X-ray diagnostic apparatus 20 comprises a simulated X-ray image generating means 33 for generating a simulated X-ray image projected on the detection face of an X-ray detector of a virtual X-ray diagnostic apparatus from three-dimensional image data of a subject P; X-ray image collecting means 21, 22, 23, 24, 25, 26, 27 and 28 for collecting X-ray images of the subject P by performing the X-ray photography; and a display means 30 for displaying the X-ray images and the simulated X-ray image. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

The present invention radiates X-rays to the subject relates to an X-ray diagnostic equipment for acquiring X-ray image for diagnosis by detecting the X-rays transmitted through the object, in particular, a separately collected 3 using the dimension image data to generate a simulated X-ray image of the subject, relates the generated simulated X-ray image in the X-ray diagnostic equipment to be displayed along with the X-ray image obtained by X-ray diagnosis.

  Conventionally, treatment using a radiological diagnostic apparatus such as an X-ray diagnostic apparatus is known as IVR (interventional radiology). Unlike general X-ray diagnosis, IVR is performed using a dedicated X-ray diagnostic apparatus in an imaging room equipped with equipment equivalent to an operating room. That is, the IVR examination is performed mainly by observing an X-ray fluoroscopic image obtained by X-ray fluoroscopy.

  FIG. 23 is a configuration diagram of a conventional X-ray diagnostic apparatus used for IVR (see, for example, Patent Document 1).

  In the conventional X-ray diagnostic apparatus 1, when a movement command for the bed 2 and the C-arm type stand 4 is input from the input device 3 to the system controller 5 with the subject P set on the bed 2, the system controller 5. Controls the bed controller 6 and the stand controller 7 by giving control signals. Then, the couch controller 6 controls the position by moving the couch 2 according to the control signal from the system controller 5. On the other hand, the stand control unit 7 controls the angle of the C-arm type stand 4 in accordance with a control signal from the system controller 5.

  As a result, the diagnostic region of the subject P is disposed between the X-ray generation source 8 and the X-ray detector 9 provided opposite to each other at both ends of the C-arm type stand 4. Next, when an X-ray exposure condition and an image acquisition condition are input from the input device 3 to the system controller 5, the system controller 5 gives the X-ray exposure condition to the high voltage generator 10, while Are given to the X-ray detector 9. The high voltage generator 10 supplies a tube current having a predetermined pulse width with a predetermined tube voltage to an X-ray tube included in the X-ray generation source 8 in accordance with the X-ray exposure conditions. As a result, X-rays having a desired energy are emitted from the X-ray generation source 8 toward the diagnostic region of the subject P. Then, X-rays that have been exposed from the X-ray tube of the X-ray generation source 8 and transmitted through the subject P are detected by the X-ray detector 9.

  X-rays detected by the X-ray detector 9 are output to the system controller 5 as image data. Image data obtained from the X-ray detector 9 by the system controller 5 is output to the monitor 11 as an X-ray image. The image data is given to the image processing unit 12 as necessary, and various image processing is performed by operating the input device 3. The processed image data after the image processing is given to the system controller 5 and outputted to the monitor 11. Further, the image data that needs to be saved is written and saved from the system controller 5 to the image storage unit 13.

The surgeon then treats the subject P as a patient while examining the X-ray image displayed on the monitor 11.
JP 2001-56382 A

  In the conventional X-ray fluoroscopy, when the body thickness of the subject P is large, the magnitude of the tube current supplied to the X-ray tube in order to ensure the incident dose of the transmitted X-rays to the X-ray detector 9. By controlling the pulse width and tube voltage, the output of the X-rays to be exposed is increased. Usually, since there is a limit to the X-ray output that can be increased only by controlling the magnitude of the tube current and the pulse width, the tube voltage is also increased.

  However, when the tube voltage to the X-ray tube is increased, there is a problem that the spectrum of the exposed X-ray is shifted to a higher energy side and the contrast of the acquired X-ray image is lowered.

  Moreover, in the conventional X-ray diagnostic apparatus 1, in order to reduce the exposure of the subject P, an X-ray filter that cuts low energy components of X-rays generated from the X-ray tube is used. However, even when the low-energy component of the X-ray is filtered by the X-ray filter, the X-ray spectrum is shifted to the high energy side, leading to a decrease in the contrast of the X-ray image.

  In addition, when the subject P is thick, X-rays scattered in the subject P (scattered X-rays) increase, and the contrast of the X-ray image decreases due to the influence of the scattered X-rays. is there.

  Further, it can be said that the X-ray image is a kind of projection image from the focal point of the X-ray to the incident surface of the X-ray detector 9. For this reason, information in a direction perpendicular to the incident surface of the X-ray detector 9 cannot be obtained from the X-ray image, and necessary diagnostic information is obtained when the IVR is advanced along the blood vessel. There is a risk of inconvenience. On the other hand, when a three-dimensional image in the subject P is obtained in advance by an imaging method such as magnetic resonance imaging (MRI), a lesion in the blood vessel is examined by examining the three-dimensional image. The position of can be grasped.

  However, when an instrument such as a stent is placed in a blood vessel in order to treat the lesion in the blood vessel during the X-ray examination, it is necessary for the operator to know the position of the lesion on the X-ray image. I have to rely on judgment. As a result, whether or not the determination of the position of the lesion is accurate depends on the experience and skill of the operator.

The present invention has been made to cope with such a conventional situation, and image information that is difficult to be displayed on an X-ray image despite being useful in diagnosis in IVR is used as a reference image having a high contrast. by additionally displayed, and an object thereof is to provide an X-ray diagnostic equipment capable of supporting the image recognition of the operator increase the efficiency of the X-ray examination.

In order to achieve the above object, an X-ray diagnostic apparatus according to the present invention is based on storage means for storing three-dimensional image data of a subject and the three-dimensional image data. A simulated X-ray image generating means for generating a simulated X-ray image projected on a detection surface of an X-ray detector of a virtual X-ray diagnostic apparatus taking into account a plurality of X-ray energies; and correcting the simulated X-ray image X-ray image acquisition means for acquiring an X-ray image of the subject by executing X-ray imaging for obtaining, a positional deviation amount between the X-ray image and the simulated X-ray image, and the positional deviation amount correction means and, have a, and a display means for displaying the X-ray image and the corrected simulated X-ray image, the simulated X-ray image generating means for correcting the simulated X-ray image based on, the 3 Attribute information of organ in each voxel in dimensional image data Based on the assignment, the X-ray absorption characteristics of the elements assigned to the respective voxels based on the attribute information of the organs, and based on the X-ray energy spectrum obtained from the imaging conditions and the X-ray absorption characteristics assigned to the respective voxels The simulated X-ray image is generated . Alternatively, the X-ray diagnostic apparatus according to the present invention includes a storage unit that stores three-dimensional image data of a subject and the three-dimensional image data as described in claim 2 in order to achieve the above-described object. A simulated X-ray image generating means for generating a simulated X-ray image projected on the detection surface of the X-ray detector of the virtual X-ray diagnostic apparatus considering a plurality of X-ray energies, and the simulated X-ray image; X-ray image acquisition means for acquiring an X-ray image of the subject by executing X-ray imaging for correcting the position, a positional deviation amount between the X-ray image and the simulated X-ray image is obtained, and the position A correction unit that corrects the simulated X-ray image based on a shift amount; and a display unit that displays the X-ray image and the corrected simulated X-ray image. The simulated X-ray image generation unit includes: An organ genus is assigned to each voxel in the 3D image data. Information is allocated, element configuration information indicating the configuration of the element is allocated to each voxel in the three-dimensional image data from the composition information of the elements configuring the organ based on the attribute information of the organ, and the element configuration information and the element Assigning an X-ray absorption characteristic to each voxel in the three-dimensional image data based on the X-ray absorption characteristic of the X-ray, obtaining an X-ray energy spectrum used for the X-ray imaging and an X-ray projection direction; The simulated X-ray image is generated according to the energy spectrum of the X-ray, the projection direction of the X-ray, and the X-ray absorption characteristic assigned to each voxel.

Further, X-ray diagnostic apparatus according to the present invention, in order to achieve the object described above, as described in claim 15, storage means for storing three-dimensional image data of the object, the three-dimensional image data A simulated X-ray image generating means for generating a simulated X-ray image projected on the detection surface of the X-ray detector of the virtual X-ray diagnostic apparatus considering a plurality of X-ray energies, and X-ray imaging X-ray image collection means for collecting an X-ray image of the subject, and display means for displaying the X-ray image and the simulated X-ray image, and the simulated X-ray image generation means, An organ allocating unit that assigns organ attribute information to each voxel in the three-dimensional image data, and based on the organ attribute information, composition information of elements constituting the organ is assigned to each voxel in the three-dimensional image data. Element structure showing the element composition A constituent element assigning section for assigning information; an absorption characteristic assigning section for assigning an X-ray absorption characteristic to each voxel in the three-dimensional image data based on the element constituent information and an X-ray absorption characteristic of the element; and the X-ray Imaging condition acquisition means for acquiring an X-ray energy spectrum and an X-ray projection direction used for imaging, the X-ray energy spectrum, the X-ray projection direction, and the X-ray absorption assigned to each voxel And an image creating unit that generates the simulated X-ray image according to characteristics.

Oite the X-ray diagnostic equipment according to the present invention, despite being useful diagnostically in IVR, additionally displaying the difficult image information be displayed on the X-ray image as a high reference image contrast By doing so, it is possible to support the operator's image recognition and to improve the efficiency of the X-ray examination.

It will be described with reference to the accompanying drawings showing a preferred embodiment of the X-ray diagnostic equipment according to the present invention.

  FIG. 1 is a block diagram showing a first embodiment of an X-ray diagnostic apparatus according to the present invention.

  The X-ray diagnostic apparatus 20 includes an X-ray generation source 21, an X-ray detector 22, a bed 23, a bed control unit 24, a C-arm type stand 25, a stand control unit 26, a high voltage generator 27, a system controller 28, and an input device. 29, a monitor 30, an image processing unit 31, an image storage unit 32, and a simulated X-ray image generation device 33. The X-ray generation source 21 and the X-ray detector 22 are respectively provided at both ends of the C-arm type stand 25 and are arranged to face each other. A bed 23 is provided between the X-ray generation source 21 and the X-ray detector 22, and the subject P is set on the bed 23. Then, the X-ray detector 22 is configured to detect X-rays that are exposed from the X-ray tube included in the X-ray generation source 21 and pass through the subject P.

  A high voltage generator 27 is connected to the X-ray generation source 21. When a tube current is supplied from the high voltage generator 27 to the X-ray tube of the X-ray generation source 21, X-rays are exposed from the X-ray generation source 21. The high voltage generator 27 can control the energy of X-rays exposed to the subject P by controlling the tube voltage and tube current supplied to the X-ray tube. The high voltage generator 27 is connected to the system controller 28. The high voltage generator 27 outputs X-ray information such as tube voltage and tube current supplied to the X-ray tube to the system controller 28, while being controlled by a control signal from the system controller 28.

  The X-ray detector 22 is connected to the system controller 28. The X-ray detector 22 collects image data by detecting X-rays, outputs the collected image data to the system controller 28, and collects the image data according to the image collection condition instructed by the system controller 28. Configured.

  The couch 23 is provided with a couch controller 24. The bed 23 is configured to be moved by control from the bed control unit 24. The couch controller 24 is connected to the system controller 28. The bed control unit 24 outputs bed information such as the position of the bed 23 to the system controller 28, while being controlled by a control signal from the system controller 28.

  The C arm type stand 25 is provided with a stand control unit 26. The C-arm type stand 25 is configured such that the angle with respect to the subject P can be arbitrarily changed by angle control from the stand control unit 26. The stand control unit 26 is connected to the system controller 28. The stand control unit 26 outputs supporter information such as the position of the C-arm type stand 25 to the system controller 28, while being controlled by a control signal from the system controller 28.

  An input device 29, a monitor 30, an image processing unit 31, and an image storage unit 32 are connected to the system controller 28. The system controller 28 gives control signals to the X-ray detector 22, the high voltage generator 27, the bed control unit 24, and the stand control unit 26 according to the X-ray exposure conditions and image acquisition conditions received from the input device 29. Function to control. Further, the system controller 28 has a function of outputting image data acquired from the X-ray detector 22 or the image processing unit 31 to the image processing unit 31, the image storage unit 32, and the monitor 30. The monitor 30 can be composed of a display device such as a CRT (Cathode-Ray Tube).

  The image processing unit 31 has a function of performing various image processing on image data acquired from the X-ray detector 22 via the system controller 28 and a function of outputting the image data after image processing to the system controller 28. ing.

The simulated X-ray image generation apparatus 33 is connected to a 3D image diagnostic apparatus 35 such as an MRI apparatus or a computed tomography (CT) apparatus or a 3D image server 36 via a network 34. The simulated X-ray image generation apparatus 33 acquires 3D image data of the subject P collected in advance from a 3D image diagnostic apparatus 35 such as an MRI apparatus or a CT apparatus or a 3D image server 36, and acquires 3D image data. And a function for creating a simulated X-ray image of the subject P from the image and a function for displaying the created simulated X-ray image on the monitor 30. Here, the simulated X-ray image is an X-ray projection image of the subject P onto the detection surface of the X-ray detector 22 provided in the virtual X-ray diagnostic apparatus. The projection direction of the simulated X-ray image can be arbitrarily set. However, if the irradiation direction of the X-ray beam irradiated to the subject P in the X-ray fluoroscopic imaging is used, an image effective for diagnosis is obtained.

  FIG. 2 is a functional block diagram of the simulated X-ray image generation apparatus 33 shown in FIG.

  The simulated X-ray image generation apparatus 33 includes a three-dimensional image acquisition unit 40, a constituent element database 41, a segmentation unit 42, a constituent element assignment unit 43, a scattering cross section acquisition unit 44, an X-ray information conversion unit 45, and a simulated direct ray for each energy. An image generation unit 46, a direct line addition image generation unit 47, an image level adjustment / gamma conversion unit 48, and a simulated X-ray image display processing unit 49 are provided. Segmentation unit 42, constituent element allocation unit 43, scattering cross section acquisition unit 44, X-ray information conversion unit 45, energy-specific simulated direct line image generation unit 46, direct line addition image generation unit 47, image level adjustment / gamma conversion unit 48 The simulated X-ray image display processing unit 49 can be constructed by causing a computer to read a program. However, some or all of them may be configured by a circuit.

  The three-dimensional image acquisition unit 40 searches the three-dimensional image data stored in the three-dimensional image diagnostic apparatus 35 or the three-dimensional image server 36 via the network 34 and simulates the subject P to be subjected to fluoroscopic diagnosis. It has a function of acquiring 3D image data necessary for creating X-ray image data and a function of supplying the acquired 3D image data to the segmentation unit 42.

  In the constituent element database 41, composition information of substances constituting various organs is stored as constituent element data. The constituent element data includes at least the density of a substance constituting each organ.

  The segmentation unit 42 assigns an index indicating which organ the volume element is to a volume element (voxel) at each position of the 3D image data received from the 3D image acquisition unit 40, and adds the index 3 A function of giving the dimensional image data to the constituent element assigning unit 43.

  The constituent element assigning unit 43 refers to the constituent element data of the organ stored in the constituent element database 41, so that the composition of the substance constituting each organ in the three-dimensional image data with the organ index received from the segmentation unit 42 is obtained. A function of assigning information, and a function of providing the energy-specific simulated direct line image generation unit 46 with the three-dimensional image data assigned with the composition information of the substance.

  The scattering cross section acquisition unit 44 has a function of acquiring a scattering cross section representing an interaction between photons constituting X-rays and each element constituting the organ, and the obtained scattering cross sections are simulated direct line images classified by energy. A function to be given to the generation unit 46.

  The X-ray information conversion unit 45 has a function of acquiring imaging conditions necessary for creating a simulated X-ray image from the system controller 28, and detects X-rays from the X-ray tube when the subject P does not exist based on the acquired imaging conditions. A function of calculating the number of photons of X-rays incident on one pixel on the detector 22 and a function of supplying the number of photons of X-rays obtained by the calculation to the simulated direct line image generation unit 46 according to energy together with imaging conditions.

  The simulated direct-line image generation unit 46 by energy includes the three-dimensional image data and the X-ray information to which the scattering cross section of each element received from the scattering cross section acquisition unit 44 and the composition information of the substance received from the constituent element allocation unit 43 are allocated. Based on the imaging conditions in the X-ray fluoroscopic imaging received from the conversion unit 45 and the number of photons of X-rays incident on one pixel on the X-ray detector 22 from the X-ray tube when the subject P does not exist, It has a function of generating a simulated X-ray image of a direct line and a function of supplying the generated simulated X-ray image of a direct line for each energy to the direct line addition image generating unit 47.

  The direct line addition image generation unit 47 generates a simulated X-ray image of a direct line by weighting and adding the simulated X-ray image of the direct line for each energy received from the simulated direct line image generation unit for each energy. And a function of supplying the generated simulated X-ray image of the direct line to the image level adjustment / gamma conversion unit 48.

  The image level adjustment / gamma conversion unit 48 has a function of performing image level adjustment and gamma conversion of a simulated X-ray image of a direct line received from the direct line addition image generation unit 47, and a direct adjustment after image level adjustment and gamma conversion. A function of giving a simulated X-ray image of the line to the simulated X-ray image display processing unit 49.

  The simulated X-ray image display processing unit 49 has a function of giving a simulated X-ray image of a direct line received from the image level adjustment / gamma conversion unit 48 to the monitor 30 for display.

  Next, the operation and action of the X-ray diagnostic apparatus 20 will be described.

  FIG. 3 is a flowchart showing a flow until the simulated X-ray image is generated by the X-ray diagnostic apparatus 20 shown in FIG. 1 and the generated simulated X-ray image is displayed together with the X-ray image. Reference numerals attached indicate steps in the flowchart.

  First, prior to the fluoroscopic examination, three-dimensional image data of the subject P is collected in advance by the three-dimensional image diagnostic apparatus 35 such as an MRI apparatus or a CT apparatus. The collected three-dimensional image data is subjected to image processing as necessary and stored in an image server.

  In step S <b> 1, three-dimensional image data is acquired by the simulated X-ray image generation device 33 of the X-ray diagnostic apparatus 20. That is, the three-dimensional image acquisition unit 40 searches the three-dimensional image data stored in the three-dimensional image diagnostic apparatus 35 or the three-dimensional image server 36 via the network 34, and the subject P that is the target of the fluoroscopic diagnosis. 3D image data necessary for creating the simulated X-ray image data is acquired. Then, the 3D image acquisition unit 40 provides the acquired 3D image data to the segmentation unit 42.

Next, in step S <b> 2, the segmentation unit 42 has a volume element (dx, dy) at each position (x, y, z) of the three-dimensional image data S (x, y, z) received from the three-dimensional image acquisition unit 40. , dz) is assigned an index Org (x, y, z) indicating which organ the volume element (dx, dy, dz) is. Thereby, the three-dimensional image data is segmented for each organ type. The index Org (x, y, z) can be defined, for example, as in Expression (1).
[Equation 1]
Org (x, y, z)
= 1: Blood
= 2: Blood vessel wall
= 3: Brain gray matter
= 4: Brain white matter
(1)

  The segmentation unit 42 gives the three-dimensional image data S (x, y, z) to which the organ index Org (x, y, z) is added to the constituent element assignment unit 43.

  Next, in step S3, the constituent element assigning unit 43 refers to the constituent element data of the organ stored in the constituent element database 41 to add a three-dimensional image to which the organ index Org (x, y, z) is added. The composition information of the substances constituting each organ is assigned to the data S (x, y, z).

  FIG. 4 is a diagram showing an example of constituent element data stored in the constituent element database 41 shown in FIG.

As shown in FIG. 4, physical property values such as various organ densities (g / cm ³ or atom / cm ³ ), atomic numbers of constituent atoms and weight composition ratios are stored in the constituent element database 41 as constituent element data. Saved. Some of the constituent element data are publicly available, for example, published by the National Institute of Standards and Technology (NIST).

  The constituent element assigning unit 43 is a constituent element database based on the organ index Org (x, y, z) assigned to each position (x, y, z) of the three-dimensional image data S (x, y, z). The density ρZ of the element of atomic number Z constituting the corresponding organ is obtained from the constituent element data of the organ stored in 41. The constituent element assigning unit 43 assigns the element density ρZ (x, y, z) to the volume element (dx, dy, dz) at each position (x, y, z) of the three-dimensional image data. The constituent element assigning unit 43 gives the three-dimensional image data S (x, y, z) to which the density ρZ (x, y, z) is assigned to the simulated direct line image generating unit 46 for each energy.

On the other hand, in step S4, the scattering cross section acquisition unit 44 performs Compton scattering, photoelectric effect, electron positron pair generation, Rayleigh scattering, etc. occurring between photons of energy E constituting X-rays and elements Z constituting the organ. The scattering cross section σZ (E) (cm ² / atom) representing the interaction is acquired. The scattering cross section σZ (E) can be obtained from a publicly available database.

  For example, NIST has published XCOM as an evaluated photon cross-section database for personal computers for determining the scattering cross-section σZ (E) of elements with atomic numbers of 100 or less in the range of photon energy from 1 keV to 100 GeV. Yes.

  FIG. 5 is a diagram showing the scattering cross section σZ (E) of carbon obtained by the scattering cross section acquisition unit 44 shown in FIG.

In FIG. 5, the horizontal axis represents photon energy (MeV), and the vertical axis represents carbon cross-sectional area (barns / atom). Note that since there is a relationship of 1 barn = 10 ⁻²⁴ cm ² , the unit of the cross-sectional area can be converted from (barns / atom) to (cm ² / atom).

  Also, the solid line in FIG. 5 is the scattering cross section σZ (E) indicating the total attenuation due to coherent scattering, the dotted line is the coherent scattering cross section, the one-dot chain line is the incoherent scattering cross section, and the two-dot chain line is the photoelectric absorption. The cross-sectional area is shown.

  The scattering cross section acquisition unit 44 gives the acquired scattering cross sections of the elements to the simulated direct line image generation unit 46 by energy.

  On the other hand, in step S5, X-ray fluoroscopic imaging is performed by exposing X-rays to the subject P. That is, when a movement command for the bed 23 and the C-arm type stand 25 is input from the input device 29 to the system controller 28 with the subject P set on the bed 23, the system controller 28 causes the bed controller 24 and A control signal is given to the stand control unit 26 for control. Then, the bed control unit 24 controls the position by moving the bed 23 according to the control signal from the system controller 28. On the other hand, the stand control unit 26 controls the angle of the C-arm type stand 25 in accordance with a control signal from the system controller 28.

  As a result, the diagnostic region of the subject P is disposed between the X-ray generation source 21 and the X-ray detector 22 provided opposite to each other at both ends of the C-arm type stand 25. Next, when an X-ray exposure condition and an image acquisition condition are input from the input device 29 to the system controller 28, the system controller 28 supplies the X-ray exposure condition to the high voltage generator 27, while Are given to the X-ray detector 22. The high voltage generator 27 supplies a tube current having a predetermined pulse width and a predetermined pulse width to the X-ray tube included in the X-ray generation source 21 according to the X-ray exposure conditions. As a result, X-rays having a desired energy are emitted from the X-ray generation source 21 toward the diagnostic region of the subject P. Then, X-rays that are exposed from the X-ray tube of the X-ray generation source 21 and pass through the subject P are detected by the X-ray detector 22.

  X-rays detected by the X-ray detector 22 are output to the system controller 28 as image data.

  Next, in step S6, the image data obtained by the system controller 28 from the X-ray detector 22 is output to the monitor 30 as an X-ray image. The image data is given to the image processing unit 31 as necessary, and various image processing is performed by operating the input device 29. The processed image data after the image processing is given to the system controller 28 and outputted to the monitor 30. Furthermore, image data that needs to be saved is written and saved from the system controller 28 to the image storage unit 32.

  On the other hand, in step S <b> 7, the X-ray information conversion unit 45 acquires various imaging conditions such as an X-ray exposure condition in X-ray fluoroscopy from the system controller 28. Then, if the subject P does not exist based on the imaging conditions, X-ray photons of energy E incident on one pixel (xd, yd) on the X-ray detector 22 from the X-ray tube of the X-ray generation source 21. Find the number Nx0_calc (E, xd, yd).

  The imaging conditions used when obtaining the number of X-ray photons include conditions for each apparatus in addition to X-ray exposure conditions such as X-ray tube voltage, tube current, and X-ray pulse width. Conditions for each apparatus include the anode material of the X-ray tube, the size of the X-ray focal point, the field of view, the X-ray filter condition, the X-ray grid condition, and the geometric condition. Examples of X-ray filter conditions include X-ray filtration conditions in an X-ray tube, X-ray filtration conditions unique to the X-ray diaphragm device, and filtration conditions using an X-ray filter. Geometric conditions include the distance from the X-ray focal point to the center of each pixel (xd, yd), the direction cosine from the X-ray focal point to the plane forming the pixel (xd, yd), and the pixel (xd , yd).

  Of the imaging conditions, the X-ray tube current and the X-ray pulse width only affect the overall image level of the simulated X-ray image to be created. The image level of the simulated X-ray image can be adjusted when displaying the simulated X-ray image. Therefore, rough values may be assumed for the X-ray tube current and the X-ray pulse width used in obtaining the X-ray photon number Nx0_calc (E, xd, yd).

The X-ray generation spectrum when the anode material of the X-ray tube is tungsten can be obtained using a calculation code such as TASMIP (tungsten anode spectral model using interpolating polynomials). Details of TASMIP are described in Boone JM, Seibert JA. Med Phys. 1997 Nov; 24 (11): 1661-70. In addition, the X-ray attenuation by the X-ray tube and X-ray diaphragm specific filtration and the X-ray filter is determined by the thickness of the attenuation material such as the filter and the scattering cross section σZ (E) (cm by XIST published by NIST ² / atom) and the element density ρ (atom / cm 2), the X-ray attenuation rate is calculated, and the X-ray photon number before filtration is multiplied by the attenuation rate.

  The X-ray information conversion unit 45 counts the number of X-ray photons of energy E incident on one pixel (xd, yd) on the X-ray detector 22 when the subject P is not present together with the imaging conditions acquired from the system controller 28. Nx0_calc (E, xd, yd) is given to the energy-specific simulated direct line image generation unit 46.

  Next, in step S <b> 8, simulated X-ray images of direct lines by energy are generated by the simulated direct line image generation unit by energy 46. For this purpose, first, the energy-specific simulated direct line image generation unit 46 configures the entire X-ray absorber included in a quadrangular pyramid that looks at one pixel (xd, yd) on the X-ray detector 22 from the X-ray focal point. The total number of atoms per unit area (Natom) of the element to be calculated is obtained. Examples of the X-ray absorber include an X-ray filter and a subject P. For the calculation of the total number of atoms (Natom) per unit area of the constituent elements of the X-ray absorber, imaging conditions in X-ray fluoroscopy received from the X-ray information conversion unit 45 are used.

  Specifically, the filtering inherent to the X-ray tube and the X-ray diaphragm device, the filter conditions of the X-ray filter, the distance between the X-ray focal point and the pixel on the X-ray detector 22, the area of the pixel, the X-ray focal point Imaging conditions such as the direction cosine from to the plane forming the pixel, the distance between the focus of the X-ray and the subject P, the direction from the focus of the X-ray to the subject P (X-ray irradiation angle), etc. It is used to calculate the total number of atoms (Natom) per unit area of the constituent elements of the absorber.

Here, the volume element (dx, dy, dz) at the position (x, y, z) included in the quadrangular pyramid that looks at one pixel (xd, yd) on the X-ray detector 22 from the focal point of the X-ray is Suppose that a (x, y, z)% of the volume is contained in the quadrangular pyramid. Then, the number of atoms dNatom_Z of the element Z contained in the volume element (dx, dy, dz) in the quadrangular pyramid can be calculated by the equation (2) using the density ρZ (x, y, z). [Equation 2]
dNatom_Z = ρZ (x, y, z) × dx × dy × dz × a (x, y, z) / 100 (2)

  Similarly, the total number of atoms Natom_Z of the element Z contained in the quadrangular pyramid is calculated by calculating and adding the number of atoms dNatom_Z of the element Z contained in all volume elements (dx, dy, dz) contained in the quadrangular pyramid. be able to. In addition, for calculating the total number of atoms Natom_Z of the element Z, the composition information of the substance received from the constituent element assignment unit 43 can be referred to.

Then, the total absorption amount ATTpat (E) of the photon of energy E in the square pyramid by the subject P can be obtained as shown in Equation (3). That is, the absorption coefficient of element Z is obtained from the scattering cross section σZ (E) of element Z received from the scattering cross section acquisition unit 44 and the total number of atoms Natom_Z, and the obtained absorption coefficient is added to all elements Z to obtain the coverage. The total absorbed amount ATTpat (E) by the specimen P is calculated. Such calculation of the total absorption amount ATTpat (E) is performed for each energy E of the X-ray spectrum, for example, for every 1 keV.
[Equation 3]
ATTpat （E） ＝ Σ _Z σZ （E） × Natom_Z (3)
However, in Formula (3), Σ _Z represents the sum total regarding the element Z.

Then. The transmittance Tpat (E) with respect to the photons having the energy E of the quadrangular pyramid can be expressed as the equation (4) by using the total absorption amount ATTpat (E) of the photons having the energy E by the subject P.
[Equation 4]
Tpat (E) = exp {−ATTpat (E)} (4)

  On the other hand, the number of photons Nx0_calc (E, xd, yd) of energy E incident on one pixel (xd, yd) on the X-ray detector 22 when there is no subject P is the X-ray as described above. In the information conversion unit 45, the calculation can be performed in consideration of the tube voltage of the X-ray tube, tube current, X-ray pulse width, pixel area, and transmittance of the X-ray filter. The X-ray photon number Nx0_calc (E, xd, yd) when there is no subject P is given from the X-ray information conversion unit 45 to the simulated direct line image generation unit 46 by energy.

Further, the number of X-ray photons Nx_calc (E, xd, yd) of energy E that passes through the subject P and enters one pixel (xd, yd) on the X-ray detector 22 is obtained when the subject P is not present. From the number of photons Nx0_calc (E, xd, yd) and the total absorption amount ATTpat (E) by the subject P, it can be obtained as in equation (5).
[Equation 5]
Nx_calc (E, xd, yd) = Nx0_calc (E, xd, yd) × Tpat (E) (5)
The number of X-ray photons Nx_calc (E, xd, yd) of energy E obtained by Expression (5) corresponds to a simulated X-ray image of direct lines for each energy. The energy-specific simulated direct line image generation unit 46 provides the direct line addition image generation unit 47 with the simulated X-ray image of the energy-specific direct line generated by the above calculation.

Next, in step S9, the direct line addition image generation unit 47 performs, for each energy, the simulated X-ray image of the direct line for each energy received from the simulated direct line image generation unit 46 for each energy as shown in Expression (6). A simulated X-ray image of a direct line is generated by weighted addition.
[Equation 6]
Nx_calc (xd, yd) = Σ _E Nx_calc (E, xd, yd) × w (E) (6)
However, in Formula (6),
Σ _E : Sum of energy E
w (E): Indicates a weight function according to energy E.

  Although the weighting function w (E) can be an arbitrary weighting function, a weighting function reflecting the X-ray absorption characteristics of the X-ray detector 22 can be used as a practical example.

  The direct line addition image generation unit 47 then supplies the generated simulated X-ray image of the direct line to the image level adjustment / gamma conversion unit 48.

Next, in step S10, the image level adjustment / gamma conversion unit 48 uses an expression for displaying the simulated X-ray image of the direct line received from the direct line addition image generation unit 47 at an appropriate image level (luminance level). As shown in (7), the image level is corrected so that the average image level in a predetermined region of interest (ROI) becomes a target predetermined image level.
[Equation 7]
Image level after correction
= Image level before correction x Target image level / Average image level within ROI (7)

  By the way, the amount of X-ray absorption is small in the thin part of the subject P such as the lung field or the body side. For this reason, the image level of the simulated X-ray image of a direct line becomes high in the portion where the subject P is thin. Therefore, the image level adjustment / gamma conversion unit 48 performs gamma conversion having a nonlinear input / output characteristic generally called a gamma curve on the simulated X-ray image of a direct line in order to prevent the image level from becoming too high.

  Then, the image level adjustment / gamma conversion unit 48 gives the simulated X-ray image of the direct line after the image level adjustment and gamma conversion to the simulated X-ray image display processing unit 49.

  Next, in step S <b> 11, the simulated X-ray image display processing unit 49 gives the simulated X-ray image of the direct line received from the image level adjustment / gamma conversion unit 48 to the monitor 30 for display. The simulated X-ray image can be displayed together with an X-ray image obtained by X-ray fluoroscopic imaging. Examples of the display method of the simulated X-ray image include a method of displaying the simulated X-ray image superimposed on the X-ray image and a method of displaying the simulated X-ray image in parallel with the X-ray image. When the simulated X-ray image and the X-ray image are displayed in parallel, the simulated X-ray image and the X-ray image may be displayed on the common monitor 30 or may be displayed on different monitors.

  In step S5, when the imaging condition changes with time, the processing from step S6 to step S11 is repeated again, and an X-ray image and a simulated X-ray image corresponding to the imaging condition are displayed on the monitor 30, respectively.

  Then, the surgeon can treat the subject P who is a patient while examining the X-ray image while referring to the simulated X-ray image displayed on the monitor 30.

  That is, the X-ray diagnostic apparatus 20 as described above is based on the three-dimensional image data collected by the three-dimensional image diagnostic apparatus 35 such as an MRI apparatus or a CT apparatus in advance of the X-ray fluoroscopic imaging. According to X-ray exposure conditions such as pulse width, geometric conditions such as X-ray tube focal distance (SID: source image distance) and patient-to-patient distance (PID), and equipment conditions such as X-ray filters A simulated X-ray image is generated, and the generated simulated X-ray image is displayed as a reference image together with an X-ray image obtained by X-ray fluoroscopic imaging.

  For this reason, according to the X-ray diagnostic apparatus 20 as described above, the contrast of the X-ray image obtained by X-ray fluoroscopic imaging is insufficient, and it is difficult to recognize the structure of the subject P. However, the surgeon can grasp the situation and proceed more safely by referring to the simulated X-ray image displayed as the reference image. In particular, even when the body thickness of the subject P is large, the human body structure of the region observed through the X-ray image can be displayed to the operator in an easy-to-understand manner, and the examination efficiency can be improved. Further, since the generated simulated X-ray image does not include the influence of scattered radiation, the image has a high contrast.

  FIG. 6 is a functional block diagram showing a simulated X-ray image generation apparatus of the X-ray diagnostic apparatus according to the second embodiment of the present invention.

  The X-ray diagnostic apparatus 20A shown in FIG. 6 is different from the X-ray diagnostic apparatus 20 shown in FIG. 1 in that the alignment unit 50 is provided in the simulated X-ray image generation apparatus 33A. Since other configurations and operations are not substantially different from those of the X-ray diagnostic apparatus 20 shown in FIG. 1, only a functional block diagram of the simulated X-ray image generation apparatus 33A is shown, and the same components are denoted by the same reference numerals and described. Is omitted.

  The alignment unit 50 of the simulated X-ray image generation apparatus 33A uses a direct X-ray image received from the direct line addition image generation unit 47 and an X-ray image received from the system controller 28. Has a function for obtaining the positional deviation amount for the X-ray image as position correction information, and a function for providing the obtained position correction information to the simulated direct line image generation unit 46 by energy.

  In addition, when receiving the position correction information from the alignment unit 50, the energy-specific simulated direct line image generation unit 46 performs position correction so that the amount of positional deviation with respect to the X-ray image becomes sufficiently small according to the position correction information. Above, it is configured to generate simulated X-ray images of direct lines by energy.

  In the X-ray diagnostic apparatus 20A, X-ray imaging of a predetermined part is performed in a predetermined direction, SID, and PID prior to the X-ray examination, and the real space in which the actual X-ray diagnostic apparatus 20A and the subject P exist is present. So that the alignment unit 50 can perform alignment between the virtual X-ray diagnostic apparatus for obtaining the simulated X-ray image and the virtual space of the three-dimensional model in which the virtual subject exists. Composed.

  Next, the operation and action of the X-ray diagnostic apparatus 20A will be described.

  FIG. 7 is a flowchart showing a flow until the position correction information of the simulated X-ray image is generated by the simulated X-ray image generation apparatus 33A shown in FIG. 6, and the reference numerals with numerals in the figure indicate steps in the flowchart. Indicates. Note that steps equivalent to those in FIG. 3 are denoted by the same reference numerals and description thereof is omitted.

  First, in steps S1 to S9, a simulated X-ray image of a direct line is generated by acquiring three-dimensional image data, performing X-ray fluoroscopy, and the like. However, X-ray fluoroscopic imaging is imaging for alignment prior to X-ray examination. Therefore, normally, an X-ray image and a simulated X-ray image corresponding to a single predetermined imaging condition serving as a reference are created.

  Next, in step S <b> 20, the registration unit 50 uses the simulated direct line X-ray image received from the direct line addition image generation unit 47 and the registration X-ray image received from the system controller 28. A positional deviation amount of the simulated X-ray image of the direct line with respect to the X-ray image is obtained as position correction information.

  Here, in the three-dimensional virtual space model, the center of gravity is at the origin, the position is determined, the front direction of the subject P is known, and the body axis direction from the foot side to the head side of the subject P is z It shall be along the axis. Then, the amount of deviation in the X-ray beam direction (Δθ_3d, Δφ_3d), the amount of deviation in the X-ray focal position (Δx_f_3d, Δy_f_3d, Δz_f_3d) and the detection in the X-ray detector 22 from the simulated X-ray image and the X-ray image of the direct line. The shift amount (Δx_d_3d, Δy_d_3d, Δz_d_3d) of the center position of the surface can be obtained. The X-ray beam direction is a direction connecting the X-ray focal point and the center of the detection surface of the X-ray detector 22.

  These shift amounts are the X-ray focal point position (x_f, y_f, z_f) in the real space, the X-ray beam direction (θ, φ) in the real space, and the center position (x_d) of the detection surface in the X-ray detector 22 in the real space. , y_d, z_d), the X-ray focal position (x_f_3d, y_f_3d, z_f_3d) of the virtual space, the X-ray beam direction (θ_3d, φ_3d) of the virtual space, the center position (x_d_3d, y_d_3d, z_d_3d) can be used as position correction information for correcting the shift amount between them. The center position (0, 0, 0) of the subject P was used as the origin of the real space and the virtual space.

  That is, if the position correction information is used, the degree of coincidence between the simulated X-ray image obtained by the three-dimensional model in the virtual space and the X-ray image obtained by imaging is maximized while maintaining the SID and PID unchanged. As described above, the X-ray focal position, the X-ray beam direction, and the center position of the detection surface of the X-ray detector in the virtual space can be corrected.

  Therefore, the alignment unit 50 stores the obtained position correction information. In the X-ray inspection, when calculating the corresponding simulated X-ray image for each energy in the virtual space in step S8, the alignment unit 50 provides the position correction information to the simulated direct line image generation unit 46 for each energy.

  In step S8 during the X-ray examination, from the positions of the X-ray diagnostic apparatus 20 and the subject P in the real space based on the position correction information received from the alignment unit 50 by the energy-specific simulated direct line image generation unit 46. The positions of the X-ray diagnostic apparatus and the subject in the virtual space are obtained. The energy-specific simulated direct line image generation unit 46 generates a simulated X-ray image of direct lines by energy using the X-ray diagnostic apparatus and the position of the subject in the obtained virtual space. Then, similarly to the flowchart shown in FIG. 3, a simulated X-ray image is displayed through step S9, step S10, and step S11.

  In other words, the X-ray diagnostic apparatus 20A as described above determines the geometric conditions used for generating the simulated X-ray image so that the maximum degree of coincidence is obtained between the simulated X-ray image and the actually captured X-ray image. I am trying to fix it. Therefore, the X-ray diagnostic apparatus 20A stores position correction information in the virtual space. Then, the simulated X-ray image corrected according to the position correction information is displayed as a reference image together with the real space X-ray image.

  For this reason, according to the X-ray diagnostic apparatus 20A, the degree of coincidence between the simulated X-ray image and the X-ray image can be improved.

  FIG. 8 is a diagram for explaining the function of the simulated X-ray image generation apparatus of the X-ray diagnostic apparatus according to the third embodiment of the present invention.

  In the X-ray diagnostic apparatus 20B according to the third embodiment, the detailed function of the X-ray information conversion unit 45 in the simulated X-ray image generation apparatus 33B is different from that of the X-ray diagnostic apparatus 20 shown in FIG. Since the other configuration and operation are not substantially different from those of the X-ray diagnostic apparatus 20 shown in FIG. 1, only a diagram for explaining the function of the simulated X-ray image generation apparatus 33B is shown, and the same configuration and operation are described. Is omitted.

The horizontal axis in FIG. 8 is a photon energy (keV), the vertical axis represents the intensity of the photon (relative value). A solid line in FIG. 8 is an X-ray spectrum S1 used for creating a simulated X-ray image in the X-ray diagnostic apparatus 20 according to the first embodiment, and a dotted line in FIG. It is an X-ray spectrum S2 used for creating a simulated X-ray image in the X-ray diagnostic apparatus 20B according to the embodiment.

  That is, the X-ray spectrum S1 used for creating the simulated X-ray image in the X-ray diagnostic apparatus 20 according to the first embodiment includes the anode material of the X-ray tube, the tube voltage of the X-ray tube, the tube current, and It is a spectrum calculated | required from X-ray exposure conditions which consist of the width | variety of an X-ray pulse, and X-ray filter conditions, such as a specific filtration and X-ray filter of an X-ray tube and an X-ray aperture apparatus. Therefore. This spectrum S1 is equivalent to the spectrum actually obtained in the X-ray diagnostic apparatus 20.

  However, as shown in FIG. 5, when the X-ray energy increases, the X-ray scattering cross section tends to decrease. For this reason, it is known that the smaller the X-ray energy, the better the contrast of the X-ray image.

  On the other hand, when the body thickness of the subject P is large, an increase in the tube current or the pulse width of the tube current is used to compensate for the decrease in the X-ray dose that passes through the subject P and enters the X-ray detector 22. Is expanded. Furthermore, if the X-ray incident dose to the X-ray detector 22 is still insufficient, the tube voltage is increased. That is, the dose of X-rays output from the X-ray tube is proportional to the third to fifth power of the tube voltage. Therefore, if the tube voltage is increased, the dose of X-rays can be increased. However, when the X-ray energy increases with an increase in the tube voltage, there is a problem that the contrast of the X-ray image decreases as described above.

  Therefore, the X-ray information conversion unit 45 of the simulated X-ray image generation apparatus 33B according to the third embodiment uses the X-ray spectrum S2 used for calculating the simulated X-ray image as shown by the dotted line in FIG. Lower energy than the spectrum of the X-ray diagnostic apparatus 20B determined from conditions such as the bipolar substance of the X-ray diagnostic apparatus 20B, the tube voltage of the X-ray tube, the inherent filtration of the X-ray tube and the X-ray diaphragm, and the X-ray filter Determine the spectrum distributed to the side. However, the X-ray spectrum S2 used for the calculation of the simulated X-ray image may be a spectrum whose average energy is lower than the average energy of the spectrum of the X-ray diagnostic apparatus 20B.

  Then, the X-ray information conversion unit 45 simulates the X-ray spectrum S2 determined independently of the X-ray spectrum exposed from the actual X-ray tube for use in the calculation of the simulated X-ray image. This is given to the line image generation unit 46. On the other hand, the energy-specific simulated direct line image generation unit 46 creates a simulated X-ray image for each energy by using the X-ray spectrum S2 for calculation of the simulated X-ray image received from the X-ray information conversion unit 45. . As a result, the simulated X-ray image created from the X-ray spectrum S2 for calculating the simulated X-ray image is displayed as a reference image together with the actually captured X-ray image.

  For this reason, according to the X-ray diagnostic apparatus 20B according to the third embodiment as described above, even when the X-ray energy to be exposed is large as in the case where the body thickness of the subject P is thick. A simulated X-ray image with good contrast can be obtained. As a result, even if the X-ray image has little contrast and it is difficult to recognize the structure of the subject P, the surgeon can know the situation from the simulated X-ray image and can proceed with the examination safely. Become.

  FIG. 9 is a functional block diagram showing a simulated X-ray image generation apparatus of the X-ray diagnostic apparatus according to the fourth embodiment of the present invention.

  The X-ray diagnostic apparatus 20C shown in FIG. 9 is different from the X-ray diagnostic apparatus 20 shown in FIG. 1 in that the deformation correction unit 60 is provided in the simulated X-ray image generation apparatus 33C. Since other configurations and operations are not substantially different from those of the X-ray diagnostic apparatus 20 shown in FIG. 1, only a functional block diagram of the simulated X-ray image generation apparatus 33C is shown, and the same components are denoted by the same reference numerals and described. Is omitted.

  The deformation correcting unit 60 of the simulated X-ray image generation apparatus 33C directly simulates a direct line from the simulated X-ray image of the direct line received from the direct line addition image generating unit 47 and the X-ray image received from the system controller 28. A function for obtaining a positional deviation amount due to deformation of an X-ray image as deformation correction information, and correcting and correcting image distortion due to deformation by deforming and correcting a simulated X-ray image of a direct line according to the obtained deformation correction information. A function of giving a simulated X-ray image of a direct line to the image level adjustment / gamma conversion unit 48.

  On the other hand, the image level adjustment / gamma conversion unit 48 is configured to perform image level adjustment and gamma conversion on the simulated X-ray image of a direct line after modification.

  Next, the operation and action of the X-ray diagnostic apparatus 20C will be described.

  FIG. 10 is a flowchart showing a flow until a simulated X-ray image subjected to deformation correction by the simulated X-ray image generating apparatus 33C shown in FIG. 9 is displayed. In FIG. Steps are shown. Note that steps equivalent to those in FIG. 3 are denoted by the same reference numerals and description thereof is omitted.

  First, in steps S1 to S9, a simulated X-ray image of a direct line is generated by acquiring three-dimensional image data, performing X-ray fluoroscopy, and the like.

  Next, in step S <b> 30, the deformation correction unit 60 uses the simulated direct X-ray image for alignment received from the direct line addition image generation unit 47 and the alignment X-ray image received from the system controller 28. The distortion amount due to the deformation of the direct X-ray image of the simulated X-ray image is obtained as deformation correction information. Then, the deformation correction unit 60 corrects the image distortion due to the deformation of the simulated X-ray image of the direct line according to the obtained deformation correction information. That is, each position of the direct X-ray image is matched with each corresponding position of the X-ray image by distorting the direct X-ray image.

Specifically, the simulated X-ray image weighted and added for energy is compared with the X-ray image, and the simulated X-ray image is rotationally moved, translated, corrected in the projection direction, and warped so that the degree of coincidence is maximized. . The coincidence degree M of the simulated X-ray image can be defined as shown in Equation (8), for example.
[Equation 8]
M = Σ _image {Nx (xd, yd)-Nx_calc (xd, yd)} ² (8)
However, in Formula (8),
Nx (xd, yd): X-ray image
Nx_calc (xd, yd): Simulated X-ray image Σ _image : Total for all pixels in the image.

  Note that minimizing the value of the degree of coincidence M obtained by equation (8) corresponds to maximizing the degree of coincidence. Therefore, the simulated X-ray image may be rotated and translated so that the coincidence value M shown in Expression (8) is minimized.

  Up to this point, it is assumed that the matrix sizes of the X-ray image and the simulated X-ray image are the same. However, if the matrix sizes of the X-ray image and the simulated X-ray image are different from each other, the matching degree M As a pre-process for calculating, the matrix size of one or both of the X-ray image and the simulated X-ray image may be converted. The matrix size reduction conversion is performed by calculating pixel values on the image after the matrix size reduction conversion by an interpolation operation using four pixels close to the corresponding pixels on the image before the matrix size reduction conversion. be able to.

  Further, the rotational movement and parallel movement of the simulated X-ray image are the rotational movement and parallel movement within the simulated X-ray image plane. The correction of the projection direction is to correct the irradiation direction of the X-ray with respect to the subject P input to the X-ray information conversion unit 45 as an imaging condition from the system controller 28 as the original projection direction. Warp is a process of distorting a simulated X-ray image. Warp is a technique devised for the purpose of overlaying multiple images, details of which are, for example, Ishida T, et al, Iterative image warping technique for temporal subtraction of sequential chest radiographs to detect interval change. Med Phys 26: 1320- 1329, 1999.

  In order to reduce the amount of calculation for correcting the deformation of the simulated X-ray image, image matching may be performed by performing only rotational movement, parallel movement, and warping of the simulated X-ray image.

  Then, the deformation correction unit 60 gives the simulated X-ray image of the direct line after the deformation correction to the image level adjustment / gamma conversion unit 48.

  Next, in step S10, the image level adjustment / gamma conversion unit 48 performs image level adjustment and gamma conversion on the simulated X-ray image of the direct line after the modification. In step S11, a simulated X-ray image of a direct line after deformation correction is displayed.

  That is, the X-ray diagnostic apparatus 20C as described above is configured to correct the deformation of the simulated X-ray image in consideration of the deformation of the subject P. Note that the X-ray diagnostic apparatus 20A shown in FIG. 2 corrects the positional deviation of the simulated X-ray image using the position correction information. That is, the position correction information used in the X-ray diagnostic apparatus 20A includes an X-ray image and a simulated X-ray that are actually captured on the assumption that the virtual X-ray diagnostic apparatus and the three-dimensional model of the virtual subject are not deformed. This is information for correcting the positional deviation of the line image as the positional deviation of the three-dimensional model.

  However, the three-dimensional model of the subject P is usually deformed between the time when the three-dimensional image data is collected and the time when the X-ray examination is performed. Therefore, there is a possibility that the accuracy of the simulated X-ray image may be insufficient only by correcting the positional shift in the X-ray diagnostic apparatus 20A shown in FIG. In particular, in the case where a simulated X-ray image is superimposed on an image obtained by other calculations, the accuracy of the simulated X-ray image is problematic.

  On the other hand, in the X-ray diagnostic apparatus 20C, the X-ray image is compared with the simulated X-ray image, and the simulated X-ray image is distorted so that each position of the simulated X-ray image corresponds to the position corresponding to the X-ray image. Therefore, even if the subject P is deformed, a simulated X-ray image can be obtained with better positional accuracy.

  FIG. 11 is a functional block diagram showing a simulated X-ray image generation apparatus of an X-ray diagnostic apparatus according to the fifth embodiment of the present invention.

  In the X-ray diagnostic apparatus 20D shown in FIG. 11, the simulated X-ray image generation apparatus 33D is provided with a first simulated X-ray image generation unit 70A, a second simulated X-ray image generation unit 70B, and a deformation correction unit 60. The detailed configuration and the detailed function of the X-ray information converter 45 are different from those of the X-ray diagnostic apparatus 20 shown in FIG. Since other configurations and operations are not substantially different from those of the X-ray diagnostic apparatus 20 shown in FIG. 1, only a functional block diagram of the simulated X-ray image generation apparatus 33D is shown, and the same components are denoted by the same reference numerals and described. Is omitted.

  As shown in FIG. 8, the X-ray information conversion unit 45 of the simulated X-ray image generation apparatus 33D has an X-ray spectrum obtained from imaging conditions so as to be equivalent to the X-ray spectrum of the actual X-ray diagnostic apparatus 20D. And a function of creating both a spectrum shifted to a lower energy side than an X-ray spectrum obtained from imaging conditions. Then, the X-ray information conversion unit 45 gives the X-ray spectrum obtained from the imaging conditions to the first simulated X-ray image generation unit 70A, while the X-ray spectrum shifted to the low energy side is subjected to the second simulation. The X-ray image generation unit 70B is configured to be given.

  The first simulated X-ray image generation unit 70A is formed by the first energy-specific simulated direct line image generation unit 46A and the first direct line addition image generation unit 47A, and generates energy-specific simulated direct line images shown in FIG. The same functions as those of the unit 46 and the direct line addition image generation unit 47 are provided. That is, the first energy-specific simulated direct line image generation unit 46A generates a simulated X-ray image of direct lines for each energy using the X-ray spectrum obtained from the imaging conditions received from the X-ray information conversion unit 45. And a function of giving the generated direct X-ray image of the direct line to the first direct line addition image generation unit 47A. The first direct line addition image generation unit 47A is obtained from a function for creating a simulated X-ray image of a direct line by weighting and adding a simulated X-ray image of a direct line for each energy for each energy, and an imaging condition. A function of giving the deformation correcting unit 60 a simulated X-ray image of a direct line created using the X-ray spectrum.

  The second simulated X-ray image generation unit 70B is formed by the second energy-specific simulated direct line image generation unit 46B and the second direct line addition image generation unit 47B. Second energy-specific simulated direct line image generation unit 46B generates a simulated X-ray image of direct lines by energy using the X-ray spectrum shifted from the X-ray information conversion unit 45 to the low energy side. And a function of providing the generated direct X-ray image of the direct line to the second direct line addition image generation unit 47B. The second direct line addition image generation unit 47B shifts the low-energy side to a function of creating a direct X-ray image by weighting and adding the X-ray image of the direct line for each energy for each energy. A function of giving the deformation correcting unit 60 a simulated X-ray image of a direct line created by using the X-ray spectrum.

  The deformation correction unit 60 is based on the simulated X-ray image of the direct line based on the X-ray spectrum obtained from the imaging conditions and the X-ray image received from the system controller 28 received from the first direct line addition image generation unit 47A. A function for obtaining the amount of displacement due to deformation of the direct X-ray image of the simulated X-ray image as deformation correction information, and shifting to the low energy side received from the second direct line addition image generation unit 47B according to the obtained deformation correction information It has a function of correcting the deformation of the simulated X-ray image of the direct line based on the X-ray spectrum. Further, the simulated X-ray image of the direct line after the deformation correction is given from the deformation correction unit 60 to the image level adjustment / gamma conversion unit 48.

  Next, the operation and action of the X-ray diagnostic apparatus 20D will be described.

  FIG. 12 is a flowchart showing a flow until a simulated X-ray image subjected to deformation correction by the simulated X-ray image generating apparatus 33D shown in FIG. 11 is displayed. In FIG. Steps are shown. Note that steps equivalent to those in FIG. 3 are denoted by the same reference numerals and description thereof is omitted.

  First, in steps S1 to S9, a first simulated X-ray image of a direct line is generated by acquiring three-dimensional image data, performing X-ray fluoroscopy, and the like. However, the first simulated X-ray image of the direct line is created from the X-ray spectrum obtained from the imaging conditions. The created first simulated X-ray image is given to the deformation correction unit 60 from the first direct line addition image generation unit 47A.

  Next, in step S40, the deformation correction unit 60 receives the first simulated X-ray image of the direct line based on the X-ray spectrum obtained from the imaging conditions and the system received from the first direct line addition image generation unit 47A. From the X-ray image received from the controller 28, the amount of positional deviation due to deformation of the direct X-ray simulated X-ray image with respect to the X-ray image is obtained as deformation correction information.

  On the other hand, in step S41, the second simulated X-ray image of the direct line for each energy is generated by the second simulated direct line image for each energy 46B as in step S8. However, the second simulated X-ray image of the direct line for each energy is created from the spectrum of the X-ray shifted to the low energy side. The created second simulated X-ray image for each energy is supplied from the second simulated direct line image generation unit for each energy 46B to the second direct line addition image generation unit 47B.

  Next, in step S42, the second simulated X-ray image of the direct line based on the X-ray spectrum shifted to the low energy side by the weighted addition by the second direct line addition image generation unit 47B as in step S9 is obtained. Generated. The generated second simulated X-ray image is given to the deformation correcting unit 60 from the second direct line addition image generating unit 47B.

  Next, in step S43, the deformation correction unit 60 receives the second simulated X-ray image received from the second direct line addition image generation unit 47B according to the deformation correction information created using the first simulated X-ray image. Rotational movement, parallel movement, correction of projection direction, and deformation correction such as warp. The second simulated X-ray image after deformation correction is given from the deformation correction unit 60 to the image level adjustment / gamma conversion unit 48.

  Next, after the image level adjustment and gamma conversion in step S10, the second simulated X-ray image is displayed together with the X-ray image in step S11.

  In other words, the X-ray diagnostic apparatus 20D as described above uses the X-ray energy in the actual X-ray diagnostic apparatus 20D to create deformation correction information for performing image matching in the same manner as the X-ray diagnostic apparatus 20C shown in FIG. While the first simulated X-ray image created using the energy spectrum equivalent to the spectrum is used, it is created using the energy spectrum shifted to the lower energy side from the X-ray energy spectrum in the actual X-ray diagnostic apparatus 20D. The second simulated X-ray image is subjected to deformation correction such as rotational movement, parallel movement, correction of the projection direction, and warp according to the deformation correction information.

  Therefore, according to the X-ray diagnostic apparatus 20D, a modification for performing image matching using a first simulated X-ray image created using a more realistic X-ray spectrum based on imaging conditions. While obtaining the correction information with high accuracy, a second simulated X-ray image with good contrast can be obtained using an energy spectrum shifted to the low energy side as a reference image.

  FIG. 13 is a functional block diagram showing a simulated X-ray image generation apparatus of the X-ray diagnostic apparatus according to the sixth embodiment of the present invention.

  In the X-ray diagnostic apparatus 20E shown in FIG. 13, the simulated X-ray image generation apparatus 33E is provided with a simulated scattered radiation image generation unit 80 for each energy, a scattered radiation addition image generation unit 81, and a mixed image generation unit 82. This is different from the X-ray diagnostic apparatus 20C shown in FIG. Since other configurations and operations are not substantially different from those of the X-ray diagnostic apparatus 20C shown in FIG. 9, only the functional block diagram of the simulated X-ray image generation apparatus 33E is shown, and the same components are denoted by the same reference numerals and described. Is omitted.

  The simulated scattered radiation image generation unit 80 by energy of the simulated X-ray image generation apparatus 33E has assigned the scattering cross section of each element received from the scattering cross section acquisition unit 44 and the composition information of the substance received from the constituent element allocation unit 43. Imaging conditions in X-ray fluoroscopic imaging received from the three-dimensional image data and the X-ray information conversion unit 45, and X-ray photons incident on one pixel on the X-ray detector 22 from the X-ray tube when the subject P does not exist. It has a function of generating a simulated X-ray image of scattered rays for each energy based on the number and a function of giving the generated simulated X-ray image of scattered rays for each energy to the scattered radiation added image generating unit 81.

  The scattered radiation added image generation unit 81 generates a simulated X-ray image of scattered radiation by weighting and adding the simulated X-ray image of scattered radiation by energy received from the simulated scattered radiation image generator by energy 80 for each energy. And a function of providing the mixed image creating unit 82 with the generated simulated X-ray image of the scattered radiation.

  The mixed image creating unit 82 has a function of mixing the simulated X-ray image of the direct line received from the direct line added image generating unit 47 and the simulated X-ray image of the scattered ray received from the scattered ray added image generating unit 81, A function of giving the deformation correction unit 60 a simulated X-ray image including the scattered radiation generated by. Further, the mixed image creating unit 82 transmits the direct and scattered rays to the X-ray grid using the grid characteristic values of the X-ray grid prior to mixing the simulated X-ray images of the direct and scattered rays as necessary. Configured to calculate quantities.

  Then, the deformation correcting unit 60 deforms the simulated X-ray image including the scattered radiation from the simulated X-ray image including the scattered radiation received from the mixed image creating unit 82 and the X-ray image received from the system controller 28 with respect to the X-ray image. Is obtained as deformation correction information, and the deformation correction of the simulated X-ray image including the scattered radiation is performed according to the obtained deformation correction information.

  Next, the operation and action of the X-ray diagnostic apparatus 20D will be described.

  FIG. 14 is a flowchart showing a flow until a simulated X-ray image subjected to deformation correction by the simulated X-ray image generating apparatus 33E shown in FIG. 13 is displayed. Reference numerals with numerals in FIG. Steps are shown. Note that steps equivalent to those in FIG. 10 are denoted by the same reference numerals and description thereof is omitted.

First, in steps S1 to S9, a simulated X-ray image of a direct line is generated by acquiring three-dimensional image data, performing X-ray fluoroscopy, and the like. The generated simulated X-ray image of the direct line is given from the direct line addition image generation unit 47 to the mixed image generation unit 82. The direct X-ray image Nx_calcP (xd, yd) of the direct line is expressed by the weighting function w (E) corresponding to the energy E and the X-ray image Nx_calcP (E , xd, yd). That is, a direct X-ray image Nx_calcP (E, xd, yd) is calculated by multiplying the simulated X-ray image Nx_calcP (xd, yd) of the direct line by the weighting function w (E). Ask.
[Equation 9]
Nx_calcP (xd, yd) = Σ _E Nx_calcP (E, xd, yd) × w (E) (9)

  Next, in step S <b> 50, the simulated scattered radiation image generation unit 80 by energy allocates the scattering cross section of each element acquired from the scattering cross section acquisition unit 44 and the composition information of the substance acquired from the constituent element allocation unit 43. The imaging conditions in the X-ray fluoroscopic imaging acquired from the image data and the X-ray information conversion unit 45, and the number of photons of X-rays incident on one pixel on the X-ray detector 22 from the X-ray tube when the subject P does not exist. Based on this, a simulated X-ray image of scattered radiation by energy is generated.

  The interaction between X-rays and matter is a stochastic process described by the scattering cross section. Methods for simulating this stochastic process are published in, for example, the National Research Council of Canada Report NRC-PIRS-0436, the National Laboratory for High Energy Physics Report KEK Internal 94-4, and the Stanford Linear Accelerator Center Report SLAC-PUB-6499. .

  Therefore, the scattered radiation can be calculated by simulating the scattering of the X-ray photons generated from the X-ray tube in the subject P by a published method. Actually, simulation results are calculated as direct rays and scattered rays. The direct line is an X-ray that directly reaches the X-ray detector 22 without being scattered from the X-ray focal point.

  The energy-specific simulated scattered radiation image generation unit 80 supplies the generated scattered X-ray image of energy-specific scattered radiation to the scattered radiation addition image generation unit 81.

Next, in step S51, the scattered radiation added image generation unit 81 simulates the simulated X-ray image Nx_calcS (E, xd) of the scattered rays for each energy received from the simulated scattered image image unit 80 for each energy as shown in Expression (10). , yd) is weighted and added for each energy E using a weighting function w (E) to generate a simulated X-ray image Nx_calcS (xd, yd) of scattered radiation. In other words, the simulated X-ray image Nx_calcS (xd, yd) of the scattered radiation calculated for each energy is multiplied by the weight function w (E), and the total energy is used as the simulated X-ray image Nx_calcS (E, xd, yd) of the scattered radiation. Ask.
[Equation 10]
Nx_calcS (xd, yd) = Σ _E Nx_calcS (E, xd, yd) × w (E) (10)

  The scattered radiation addition image generation unit 81 gives the generated scattered X-ray image of the scattered radiation to the mixed image creation unit 82.

  Next, in step S <b> 52, the mixed image creation unit 82 mixes the direct X-ray image of the direct line received from the direct X-ray added image generation unit 47 and the simulated X-ray image of the scattered ray. For this purpose, the grid characteristic value of the X-ray grid is referred to before mixing, and the amount of transmission of direct rays and scattered rays by the X-ray grid is obtained.

The X-ray grid used in the X-ray diagnostic apparatus 20E is intended to selectively transmit direct lines among direct lines and scattered lines incident on the X-ray detector 22. As the grid characteristic values of the X-ray grid, the contrast improvement degree K, the exposure multiple B, the selectivity Σ, and the transmittance Tp of the primary line are clarified. The contrast improvement degree K is the ratio of the transmittance of direct rays to the transmittance of all X-rays including scattered rays and direct rays, and is obtained by the equation (11-1). The exposure multiple B is the reciprocal of the total X-ray transmittance, and is obtained by the equation (11-2). The selectivity Σ is the ratio of the direct ray transmittance to the scattered ray transmittance, and is determined by the equation (11-3). Further, the transmittance Tp of the primary line is obtained by Expression (11-4).
[Equation 11]
K = Tp / Tt (11-1)
B = It / It '(11-2)
Σ = Tp / Ts (11-3)
Tp = Ip '/ Ip (11-4)
However,
Tt: Transmittance of all X-rays to the X-ray grid
Tp: Transmittance of direct line to X-ray grid
Ts: Transmittance of scattered radiation to X-ray grid
It: Incident amount to X-ray grid of all X-rays
It ': Transmission amount to the X-ray grid of all X-rays
Ip: Incident amount of direct ray to X-ray grid
Ip ′: A transmission amount of the direct line with respect to the X-ray grid.

Therefore, as shown in the equation (12), if the direct line incident on the X-ray grid, that is, the simulated X-ray image Nx_calcP (xd, yd) of the direct line is multiplied by the transmittance Tp with respect to the X-ray grid of the direct line, The direct line incident on the X-ray detector 22 can be calculated as a simulated X-ray image Nx_calcPG (xd, yd) of the direct line after passing through the X-ray grid.
[Equation 12]
Nx_calcPG (xd, yd) = Nx_calcP (xd, yd) × Tp (12)

Similarly, as shown in the equation (13), the scattered radiation incident on the X-ray grid, that is, the simulated X-ray image Nx_calcS (xd, yd) of the scattered radiation, the transmittance Ts = Tp / Σ of the scattered radiation to the X-ray grid. , The scattered radiation incident on the X-ray detector 22 can be calculated as a simulated X-ray image Nx_calcSG (xd, yd) of the scattered radiation after passing through the X-ray grid.
[Equation 13]
Nx_calcSG (xd, yd) = Nx_calcS (xd, yd) × Tp / Σ (13)

Then, as shown in the equation (14), the total of the direct X-ray image Nx_calcPG (xd, yd) and the scattered X-ray image Nx_calcSG (xd, yd) after passing through the X-ray grid is expressed as a scattered ray. It can be calculated as a simulated X-ray image Nx_calcG (xd, yd) of the included X-ray.
[Formula 14]
Nx_calcG (xd, yd) = Nx_calcPG (xd, yd) + Nx_calcSG (xd, yd) (14)

  The X-ray simulated X-ray image Nx_calcG (xd, yd) including the scattered radiation generated in this way is given from the mixed image generating unit 82 to the deformation correcting unit 60.

  Next, in step S <b> 30, the deformation correcting unit 60 uses the X-ray simulated X-ray image Nx_calcG (xd, yd) including the scattered radiation received from the mixed image creating unit 82 and the X-ray image received from the system controller 28. The amount of distortion due to deformation of the simulated X-ray image Nx_calcG (xd, yd) of X-rays including scattered rays with respect to the X-ray image is obtained as deformation correction information. Then, the deformation correction unit 60 corrects the image distortion caused by the deformation of the simulated X-ray image of the X-ray including the scattered radiation according to the obtained deformation correction information. That is, each position of the simulated X-ray image Nx_calcG (xd, yd) including the scattered radiation by distorting the simulated X-ray image Nx_calcG (xd, yd) of the X-ray including the scattered radiation corresponds to the X-ray image. Match each position you want. As a result, a simulated X-ray image Nx_calcGT (xd, yd) of X-rays including the modified scattered radiation is obtained.

Here, the maximum image matching is obtained with respect to the X-ray image, that is, the simulated X-ray image Nx_calcGT (xd, yd) after deformation correction that maximizes the degree of coincidence of the position is expressed as the simulated X-ray X of the X-ray including the scattered radiation. The deformation correction unit 60 can store deformation correction information such as a parallel movement amount, a rotational movement amount, projection direction correction information, and warp information to be obtained from the line image Nx_calcG (xd, yd). The deformation correction information stored in the deformation correction unit 60 is an optimum simulated X-ray image Nx_calcGT after deformation correction from a simulated X-ray image Nx_calcG (xd, yd) of X-rays including scattered rays as shown in Expression (15). It can be expressed as a function F indicating the process for obtaining (xd, yd).
[Equation 15]
Nx_calcGT (xd, yd) = F (Nx_calcG (xd, yd)) (15)

  The deformation correction unit 60 gives the optimum simulated X-ray image Nx_calcGT (xd, yd) after deformation correction to the image level adjustment / gamma conversion unit 48.

  Next, after the image level adjustment and gamma conversion of the simulated X-ray image Nx_calcGT (xd, yd) in step S10, the modified X-ray image Nx_calcGT (xd, yd) after modification is displayed together with the X-ray image in step S11. .

Note that a simulated X-ray image Nx_calcPGT (xd, yd) of only a direct line that does not include the scattered radiation after deformation correction may be displayed as a reference image. In this case, as shown in Expression (16), a direct line after deformation correction is obtained from a simulated X-ray image Nx_calcPG (xd, yd) of the direct line after transmission through the X-ray grid by using a function F for deformation correction. The simulated X-ray image Nx_calcPGT (xd, yd) can be calculated.
[Equation 16]
Nx_calcPGT (xd, yd) = F (Nx_calcPG (xd, yd)) (16)

  Then, after adjusting the image level and performing gamma conversion on the simulated X-ray image Nx_calcPGT (xd, yd) of the direct line after the deformation correction obtained by the equation (16), the direct line is simulated after the deformation correction. An X-ray image Nx_calcPGT (xd, yd) is displayed on the display.

  That is, when the X-ray diagnostic apparatus 20E as described above generates a simulated X-ray image, it generates a simulated X-ray image of not only a direct line component but also a scattered ray component, and simulates the direct ray component and the scattered ray component. X-ray images are matched using simulated X-ray images obtained by adding X-ray images at a predetermined mixing ratio.

  Therefore, according to the X-ray diagnostic apparatus 20E, it is possible to bring the simulated X-ray image that is the object of image matching closer to the actual X-ray image, and improve the degree of coincidence between the simulated X-ray image and the X-ray image. be able to.

  FIG. 15 is a functional block diagram showing a simulated X-ray image generation apparatus of an X-ray diagnostic apparatus according to the seventh embodiment of the present invention.

  The X-ray diagnostic apparatus 20F shown in FIG. 15 differs from the X-ray diagnostic apparatus 20 shown in FIG. 1 in that the simulated X-ray image generation apparatus 33F is provided with a projection direction changing unit 90 and a visual field changing unit 91. Since other configurations and operations are not substantially different from those of the X-ray diagnostic apparatus 20 shown in FIG. 1, only a functional block diagram of the simulated X-ray image generation apparatus 33F is shown, and the same components are denoted by the same reference numerals and described. Is omitted.

  The projection direction changing unit 90 of the simulated X-ray image generation apparatus 33F acquires the number of X-ray photons incident on the X-ray detector 22 and the imaging conditions from the X-ray information conversion unit 45, and follows the instruction information from the input device 92. Among the imaging conditions, it has a function of arbitrarily changing the X-ray projection direction and a function of giving the changed imaging conditions to the visual field changing unit 91 together with the number of X-ray photons incident on the X-ray detector 22.

  The field-of-view changing unit 91 acquires the number of X-ray photons incident on the X-ray detector 22 and the imaging conditions from the projection direction changing unit 90, and arbitrarily changes the imaging field of the imaging conditions according to the instruction information from the input device 92. And a function of giving the changed imaging condition to the energy-specific simulated direct line image generation unit 46 together with the number of X-ray photons incident on the X-ray detector 22.

  The energy-specific simulated direct line image generation unit 46 generates a simulated X-ray image of direct lines by energy according to the imaging conditions including the X-ray projection direction and field of view after the change by the projection direction changing unit 90 and the field of view changing unit 91. Configured to generate.

  Next, the operation and action of the X-ray diagnostic apparatus 20F will be described.

  FIG. 16 is a flowchart showing a flow until a simulated X-ray image is displayed by the simulated X-ray image generation apparatus 33F shown in FIG. 15, and reference numerals with numerals in the figure indicate steps in the flowchart. Note that steps equivalent to those in FIG. 3 are denoted by the same reference numerals and description thereof is omitted.

  First, in steps S1 to S7, allocation of organ constituent elements, acquisition of scattering cross sections for each element and energy, acquisition of imaging conditions, and calculation of X-ray information are executed. The imaging conditions and the X-ray information are given from the X-ray information conversion unit 45 to the projection direction changing unit 90.

  Next, when an instruction to change the X-ray projection direction from the input device 92 is given to the projection direction changing unit 90 in step S60, the projection direction changing unit 90 sets the imaging condition acquired from the X-ray information conversion unit 45. Of these, the X-ray projection direction is changed to the designated projection direction. Then, the projection direction changing unit 90 gives the changed imaging conditions to the visual field changing unit 91 together with the X-ray information.

  Next, in step S <b> 61, when an instruction for changing the field of view is given from the input device 92 to the field of view changing unit 91, the field of view changing unit 91 is designated as the field of view for shooting among the shooting conditions acquired from the projection direction changing unit 90. Change to the shooting field of view. Then, the visual field changing unit 91 gives the changed imaging conditions to the simulated direct line image generating unit 46 by energy together with the X-ray information.

  Next, in step S <b> 8, the energy-specific simulated direct line image generation unit 46 generates energy-specific direct lines according to the imaging conditions including the projection direction and field of view of the X-rays changed by the projection direction changing unit 90 and the visual field changing unit 91. A simulated X-ray image is generated. Subsequently, the simulated X-ray image created through the weighted addition processing from step S9 to step S11, the image level adjustment, and the gamma conversion is used in the table, that is, by using the changed visual field information included in the imaging conditions, the designated visual field. Only a simulated X-ray image is generated. Various processes after the generation of the simulated X-ray image are also calculated only within the designated visual field.

  In other words, the X-ray diagnostic apparatus 20F as described above is used in the actual X-ray diagnostic apparatus 20F according to the instruction information from the operator before or after the X-ray examination or during or after the X-ray examination. The X-ray projection direction and imaging field of view are changed, and a simulated X-ray image of the changed X-ray projection angle and imaging field of view can be created and displayed.

  For this reason, according to the X-ray diagnostic apparatus 20F, the X-ray projection direction for calculating the simulated X-ray image is changed by the operator's operation of the input device 92, whereby a simulated X-ray image in a desired direction is obtained. It can be displayed. According to the X-ray diagnostic apparatus 20F, information necessary in the depth direction is simulated when the operator wants to confirm information in the depth direction with respect to the projection surface of the X-ray detector 22, particularly during observation of the X-ray image. It can be presented to the operator in an easy-to-understand manner as an X-ray image. Thereby, IVR can be performed efficiently.

  In addition, according to the X-ray diagnostic apparatus 20F, it is possible to display a simulated X-ray image of a desired visual field by changing the imaging visual field for calculating the simulated X-ray image by operating the input device 92. Become. Accordingly, when the field of view of the X-ray image is changed, the field of view of the simulated X-ray image can be changed following the change of the field of view.

  On the other hand, the size of the field of view of the simulated X-ray image can be changed to be different from the field of view of the actual X-ray image. Therefore, it is possible to change only the field of view of the simulated X-ray image independently of the X-ray image. For example, by designating a field of view wider than the actual X-ray image as the field of view of the simulated X-ray image, it is possible to display a simulated X-ray image in a wider range than the region irradiated with X-rays.

  FIG. 17 is a functional block diagram showing a simulated X-ray image generation apparatus of the X-ray diagnostic apparatus according to the eighth embodiment of the present invention.

  The X-ray diagnostic apparatus 20G shown in FIG. 17 is different from the X-ray diagnostic apparatus 20 shown in FIG. 1 in that a simulated X-ray image generation apparatus 33G is provided with an organ-of-interest enhancement degree designating unit 100. Since other configurations and operations are not substantially different from those of the X-ray diagnostic apparatus 20 shown in FIG. 1, only a functional block diagram of the simulated X-ray image generation apparatus 33G is shown, and the same components are denoted by the same reference numerals and described. Is omitted.

  The organ-of-interest enhancement level designation unit 100 of the simulated X-ray image generation apparatus 33G receives the configuration information of the organ of interest instructed from the constituent element database 41 when receiving the instruction information of the organ of interest and the degree of enhancement of the organ of interest from the input device 92. It has a function of obtaining element data and obtaining the correction density by multiplying the density of the elements constituting the organ of interest by a predetermined coefficient, and a function of giving the obtained correction density to the constituent element assignment unit 43.

  Then, the constituent element assigning unit 43 uses the constituent element data of the organ stored in the constituent element database 41 and the correction density received from the organ emphasis degree specifying unit 100 to convert each organ into three-dimensional image data with an organ index. Is configured to assign composition information of substances constituting the.

  Next, the operation and action of the X-ray diagnostic apparatus 20G will be described.

  FIG. 18 is a flowchart showing a flow until a simulated X-ray image is displayed by the simulated X-ray image generation apparatus 33G shown in FIG. 17, and reference numerals with numerals in the figure indicate each step of the flowchart. Note that steps equivalent to those in FIG. 3 are denoted by the same reference numerals and description thereof is omitted.

  In step S <b> 70, when the operator inputs the organ of interest and the degree-of-enhancement instruction information to the organ-of-interest enhancement specifying unit 100 by operating the input device 92, the organ-of-interest enhancement specifying unit 100 is instructed from the constituent element database 41. The constituent element data of the organ of interest is obtained, and the correction density kρZ is obtained by multiplying the density ρZ of the element Z constituting the organ of interest by the coefficient k (> 0) determined according to the degree of enhancement. Then, the organ-of-interest enhancement degree designation unit 100 gives the obtained element Z correction density kρZ to the constituent element allocation unit 43.

  Then, in step S3, the constituent element assigning unit 43 determines that the organ index Org (x, y, z) at the position (x, y, z) of the three-dimensional image data is the designated index of the organ of interest. Then, the correction density kρZ ′ (x, y, z) of the element Z constituting the organ of interest is assigned. On the other hand, the constituent element assigning unit 43 has the density ρZ (x acquired from the constituent element database 41 at the position (x, y, z) to which the index Org (x, y, z) of the organ other than the organ of interest is attached. , y, z).

  In other steps, the same processing as in each step of FIG. 3 is performed, and the simulated X-ray image is displayed together with the X-ray image.

  Therefore, the simulated X-ray image displayed by the X-ray diagnostic apparatus 20G is created by changing the density of the organ of interest according to the enhancement degree, and thus becomes an image in which the organ of interest is emphasized or suppressed. Specifically, when 0 <k <1, it seems that X-ray absorption by the organ of interest is reduced on the simulated X-ray image. When k> 1, it seems that X-ray absorption by the organ of interest has increased on the simulated X-ray image. Therefore, in both cases of 0 <k <1 and k> 1, the contrast between the organ of interest and its surroundings becomes good, so that the visibility of the organ of interest can be improved.

  In other words, the X-ray diagnostic apparatus 20G as described above reduces or increases the density of elements constituting an organ of interest or an uninterested organ at a predetermined rate when creating a simulated X-ray image from three-dimensional image data. Thus, the contrast of the organ of interest is enhanced.

  In addition, when multiplying the density ρZ of the element Z by a predetermined coefficient k, the density ρZ of all the constituent elements Z constituting the organ of interest may be multiplied by the predetermined coefficient k (> 0), or the structure having a large X-ray absorption Only the density ρZ of the element Z may be multiplied by a predetermined coefficient k (> 0). When multiplying only the density ρZ of the constituent element Z having a large X-ray absorption by a predetermined coefficient k (> 0), the magnitude of the X-ray absorption of each element Z is determined by the scattering cross section σz (E) of the element Z and the number of atoms It can be estimated by Natom_z product σz (E) × Natom_z. Therefore, by selecting the product σz (E) x Natom_z and estimating X-ray absorption for all elements Z contained in the organ of interest, selecting single or multiple elements Z that account for the majority of X-ray absorption Can do.

  Further, not only the density of elements constituting an organ of interest or an uninterested organ, but also a composition factor of elements and an X-ray absorption coefficient may be multiplied by a predetermined coefficient.

  FIG. 19 is a functional block diagram showing a simulated X-ray image generation apparatus of the X-ray diagnostic apparatus according to the ninth embodiment of the present invention.

  In the X-ray diagnostic apparatus 20H shown in FIG. 19, the simulated X-ray image generation apparatus 33H is provided with the region-of-interest specifying unit 110, and the functions of the constituent element assignment unit 43 and the energy-specific simulated direct line image generation unit 46 are provided. This is different from the X-ray diagnostic apparatus 20 shown in FIG. Since other configurations and operations are not substantially different from those of the X-ray diagnostic apparatus 20 shown in FIG. 1, only a functional block diagram of the simulated X-ray image generation apparatus 33H is shown, and the same components are denoted by the same reference numerals and described. Is omitted.

  The region-of-interest specifying unit 110 of the simulated X-ray image generation apparatus 33H acquires the three-dimensional image data of the subject P from the three-dimensional image acquisition unit 40 and displays it on the monitor 30, and specifies the region of interest from the input device 92. When receiving the information, it has a function of notifying the constituent element allocation unit 43 or the energy-specific simulated direct line image generation unit 46 of the region information of the designated region of interest.

  The constituent element assigning unit 43 is configured to multiply the density of the element in the region of interest by a predetermined coefficient when the region information of the region of interest is notified from the region-of-interest specifying unit 110. Further, the simulated direct-line image generation unit 46 by energy changes to a quadrangular pyramid that looks at one pixel on the X-ray detector 22 from the focal point of the X-ray when the region-of-interest information is notified from the region-of-interest specifying unit 110. The absorption amount of the X-ray absorber in the contained region of interest is configured to be multiplied by a predetermined coefficient.

  Then, in the region of interest, the simulated X-ray absorber using the density multiplied by a predetermined coefficient by the constituent element allocating unit 43 or the absorption amount of the X-ray absorber multiplied by the predetermined coefficient by the energy-specific simulated direct line image generating unit 46 is used. A line image is configured to be generated. As a result, a simulated X-ray image in which the contrast of the region of interest is improved can be generated.

  Next, the operation and action of the X-ray diagnostic apparatus 20H will be described.

  FIG. 20 is a flowchart showing a flow until a simulated X-ray image is displayed by the simulated X-ray image generation apparatus 33H shown in FIG. 19, and reference numerals with numerals in S in the drawing indicate steps of the flowchart. Note that steps equivalent to those in FIG. 3 are denoted by the same reference numerals and description thereof is omitted.

  First, in step S <b> 1, three-dimensional image data of the subject P is acquired by the three-dimensional image acquisition unit 40 and given to the region-of-interest specifying unit 110.

  In step S80, the region of interest is set prior to the X-ray examination. That is, the region-of-interest specifying unit 110 displays the 3D image data of the subject P acquired from the 3D image acquisition unit 40 on the monitor 30. In contrast, the surgeon observes the three-dimensional image data displayed on the monitor 30 and operates the input device 92 to designate a region of interest. An example of the region of interest is a portion where plaque is accumulated in a blood vessel. Then, the part of interest designation information is given from the input device 92 to the part of interest designation unit 110.

  The region-of-interest designating unit 110 creates region information of the region of interest according to the region-of-interest designation information. For example, when the position (x, y, z) of the volume element is within the part of interest, the region-of-interest specifying unit 110 sets Flag (x, y, z) = 1 and conversely the position (x, y If y, z) is not within the region of interest, a function Flag (x, y, z) is created so that Flag (x, y, z) = 0. Then, the region-of-interest specifying unit 110 notifies the created function Flag (x, y, z) to the constituent element assignment unit 43 or the energy-specific simulated direct line image generation unit 46 as region information of the region of interest.

  On the other hand, in step S2, an organ index is assigned to each voxel of the three-dimensional image data.

  Next, in step S81, the constituent element assigning unit 43 assigns the composition information of the substance to the segmented organ voxels. That is, the constituent element assigning unit 43 has a density ρZ (x, y, z) of the element Z constituting the subject P in the volume element (dx, dy, dz) at the position (x, y, z) of the subject P. Is assigned. However, when the region-of-interest information is notified from the region-of-interest specifying unit 110, the constituent element assigning unit 43 multiplies the density ρZ (x, y, z) of the element Z in the region of interest by a predetermined coefficient.

Specifically, as shown in Expression (17), a predetermined coefficient j is set to the density ρZ (x, y, z) of the element Z in accordance with the value of the function Flag (x, y, z) representing the region of interest. Multiply (> 0).
[Equation 17]
ρZ_flag (x, y, z) = ρZ (x, y, z) × j (when Flag (x, y, z) = 1)
= ΡZ (x, y, z) × 1 (when Flag (x, y, z) = 0)
(17)

  That is, the density ρZ (x, y, z) of the element Z in the region of interest where Flag (x, y, z) = 1 is multiplied by a predetermined coefficient j, while Flag (x, y, z) = 0 Multiply 1 by the density ρZ (x, y, z) of the element Z outside the region of interest. Then, the three-dimensional image data to which the correction density ρZ_flag (x, y, z) multiplied by the coefficient is assigned is given from the constituent element assignment unit 43 to the simulated direct line image generation unit 46 by energy.

  Therefore, if the same process as the step shown in FIG. 3 is performed in another step, a simulated X-ray image created using the correction density of the element is displayed. For this reason, the image level of the pixel corresponding to the region of interest designated on the three-dimensional image data is different from the image level of the pixel outside the region of interest. As a result, the region of interest can be recognized on the simulated X-ray image.

  When the region-of-interest specifying unit 110 notifies the constituent element assigning unit 43 of the function Flag (x, y, z) as the region information of the region of interest, instead of notifying the energy-specific simulated direct line image generation unit 46, In step S82, the amount of absorption of the X-ray absorber in the region of interest is multiplied by a predetermined coefficient. That is, the region of interest is emphasized by the function Flag (x, y, z) in the process of generating the simulated X-ray image of the direct line for each energy.

First, all of the X-ray filter, the subject P, and the like included in a quadrangular pyramid that expects one pixel (xd, yd) on the X-ray detector 22 from the X-ray focal point by the simulated direct ray image generation unit 46 by energy. The total number of atoms Natom_Z per unit area of the element Z constituting the X-ray absorber is obtained. Then, as shown in Expression (18), the amount of absorption ATTtot (X-ray absorption by the subject P for each energy E in the X-ray spectrum is calculated from the scattering cross section σZ (E) of each element Z and the total number of atoms Natom_Z. E) is calculated.
[Equation 18]
ATTtot (E) = σ1 (E) × Natom_1 + σ2 (E) × Natom_2 + σ3 (E) × Natom_3 + ... (18)

Next, the energy-specific simulated direct line image generation unit 46 refers to the value of the function Flag (x, y, z) to determine whether the volume element included in the quadrangular pyramid is included in the region of interest. To do. Then, as shown in Expression (19), the X-ray absorption amount ATTtot (E) at the region of interest where Flag (x, y, z) = 1 is multiplied by a predetermined coefficient j ′ (> 0), while Flag The X-ray absorption amount ATTtot (E) outside the region of interest where (x, y, z) = 0 is multiplied by 1.
[Equation 19]
ATTtot_flag (E) = ATTtot (E) x j (when Flag (x, y, z) = 1)
= ATTtot (E) × 1 (when Flag (x, y, z) = 0)
(19)

  Then, a simulated X-ray image is created and displayed in another step from the corrected X-ray absorption amount ATTtot_flag (E) calculated in this way. For this reason, the image level of the pixel corresponding to the region of interest designated on the three-dimensional image data is different from the image level of the pixel outside the region of interest. As a result, the region of interest can be recognized on the simulated X-ray image.

  That is, the X-ray diagnostic apparatus 20H as described above can highlight the pixels on the simulated X-ray image corresponding to the voxel of the region of interest designated by the observer on the three-dimensional image data.

  Therefore, according to the X-ray diagnostic apparatus 20H, the position on the simulated X-ray image corresponding to the region of interest can be referred to in association with the X-ray image during the X-ray examination. For example, it is possible to display a simulated X-ray image so that the position of a lesion part previously known in another examination prior to the X-ray examination can be grasped on the X-ray image during the X-ray examination.

  FIG. 21 is a functional block diagram showing a simulated X-ray image generation apparatus of the X-ray diagnostic apparatus according to the tenth embodiment of the present invention.

  In the X-ray diagnostic apparatus 20I shown in FIG. 21, the configuration in which the electrocardiograph 120 is provided and the configuration in which the electrocardiogram synchronization unit 121 is provided in the simulated X-ray image generation apparatus 33I are shown in FIG. And different. Since other configurations and operations are not substantially different from those of the X-ray diagnostic apparatus 20 shown in FIG. 1, only a functional block diagram of the simulated X-ray image generation apparatus 33I is shown, and the same configurations are denoted by the same reference numerals. Is omitted.

  The electrocardiogram synchronization unit 121 of the simulated X-ray image generation apparatus 33I acquires the electrocardiographic waveform of the subject P measured by the electrocardiograph 120, while the simulated X-ray image heart from the simulated X-ray image display processing unit 49. It has a function of acquiring potential phase information and providing timing information to the simulated X-ray image display processing unit 49 so that the simulated X-ray image is displayed in synchronization with the electrocardiographic waveform of the subject P.

  On the other hand, the simulated X-ray image display processing unit 49 displays the simulated X-ray image for each electrocardiographic phase on the monitor 30 in synchronization with the electrocardiographic waveform in accordance with the timing information received from the electrocardiogram synchronization unit 121. Composed.

  Next, the operation and action of the X-ray diagnostic apparatus 20I will be described.

FIG. 22 is a flowchart showing the flow until a simulated X-ray image is displayed by the simulated X-ray image generation apparatus 33I shown in FIG. 21, and reference numerals with numerals in the figure indicate steps in the flowchart. Steps equivalent to those in FIG. 3 are denoted by the same reference numerals and description thereof is omitted. First, three-dimensional image data for each electrocardiographic phase is collected by the three-dimensional diagnostic imaging device 35 by electrocardiographic synchronization imaging. Three-dimensional image data for each electrocardiographic phase is stored in an image server as necessary.

  In step S <b> 1, three-dimensional image data for each electrocardiographic phase of the subject P is acquired by the three-dimensional image acquisition unit 40. The 3D image acquisition unit 40 provides the acquired 3D image data to the segmentation unit 42.

  Next, in steps S2 to S10, an X-ray image is taken, while a simulated X-ray image for each electrocardiographic phase of the subject P is created. The created simulated X-ray image for each electrocardiographic phase is given to the simulated X-ray image display processing unit 49.

  In step S90, the electrocardiograph 120 acquires the electrocardiographic waveform of the subject P during the X-ray examination. The electrocardiogram synchronization unit 121 acquires an electrocardiographic waveform of the subject P measured by the electrocardiograph 120. On the other hand, the electrocardiogram synchronization unit 121 acquires electrocardiographic phase information of the simulated X-ray image from the simulated X-ray image display processing unit 49. Then, the electrocardiogram synchronization unit 121 creates timing information so that the simulated X-ray image is displayed in synchronization with the electrocardiographic waveform of the subject P with reference to the electrocardiographic phase information. The electrocardiogram synchronization unit 121 gives the created timing information to the simulated X-ray image display processing unit 49.

  Next, in step S90, the simulated X-ray image display processing unit 49 synchronizes the simulated X-ray image for each electrocardiographic phase with the electrocardiographic waveform according to the timing information for electrocardiographic synchronization received from the electrocardiographic synchronization unit 121. Display on the monitor 30.

  When X-ray imaging is performed under electrocardiographic synchronization, a simulated X-ray image having the same phase as the electrocardiographic phase of the X-ray image is displayed at the same timing.

  That is, the X-ray diagnostic apparatus 20I as described above can display a simulated X-ray image in synchronization with an electrocardiographic waveform. Therefore, according to the X-ray diagnostic apparatus 20I, a simulated X-ray image can be displayed at an appropriate timing when X-ray imaging is performed under electrocardiographic synchronization.

  Note that the processing that does not require the imaging conditions from step S1 to step S4 in FIG. 22 may be performed prior to the X-ray examination. If the processing from step S1 to step S4 is performed prior to the X-ray inspection, it is possible to reduce the amount of calculation of processing that is a target of real-time processing during the X-ray inspection.

  A single X-ray diagnostic apparatus is configured by combining necessary functions among the various functions of the X-ray diagnostic apparatuses 20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 20H, and 20I in the above embodiments. May be. Further, instead of providing some constituent elements such as the constituent element database 41 in the simulated X-ray image generation apparatuses 33, 33A, 33B, 33C, 33D, 33E, 33F, 33G, 33H, and 33I, the simulated X-ray image generation apparatus 33, 33A, 33B, 33C, 33D, 33E, 33F, 33G, 33H, and 33I are used to send necessary information such as constituent element data from the outside to the simulated X-ray image generation devices 33, 33A, 33B, 33C, 33D, and 33E. , 33F, 33G, 33H, 33I may be obtained.

1 is a configuration diagram showing a first embodiment of an X-ray diagnostic apparatus according to the present invention. FIG. 2 is a functional block diagram of the simulated X-ray image generation apparatus shown in FIG. The flowchart which shows the flow until it produces | generates a simulated X-ray image by the X-ray diagnostic apparatus shown in FIG. 1, and displays the produced | generated simulated X-ray image with an X-ray image. The figure which shows an example of the constituent element data preserve | saved at the constituent element database shown in FIG. The figure showing the scattering cross-sectional area (sigma) Z (E) of carbon calculated | required in the scattering cross-section acquisition part shown in FIG. The functional block diagram which shows the simulation X-ray image generation apparatus of the X-ray diagnostic apparatus which concerns on the 2nd Embodiment of this invention. 7 is a flowchart showing a flow until the position correction information of the simulated X-ray image is generated by the simulated X-ray image generation apparatus shown in FIG. The figure explaining the function of the simulation X-ray image generation apparatus of the X-ray diagnostic apparatus which concerns on the 3rd Embodiment of this invention. The functional block diagram which shows the simulation X-ray image generation apparatus of the X-ray diagnostic apparatus which concerns on the 4th Embodiment of this invention. 10 is a flowchart showing a flow until a simulated X-ray image subjected to deformation correction is displayed by the simulated X-ray image generation apparatus shown in FIG. The functional block diagram which shows the simulation X-ray image generation apparatus of the X-ray diagnostic apparatus which concerns on the 5th Embodiment of this invention. 12 is a flowchart showing a flow until a simulated X-ray image subjected to deformation correction by the simulated X-ray image generation apparatus shown in FIG. 11 is displayed. The functional block diagram which shows the simulation X-ray image generation apparatus of the X-ray diagnostic apparatus which concerns on the 6th Embodiment of this invention. 14 is a flowchart showing a flow until a simulated X-ray image subjected to deformation correction is displayed by the simulated X-ray image generation apparatus shown in FIG. The functional block diagram which shows the simulation X-ray image generation apparatus of the X-ray diagnostic apparatus which concerns on the 7th Embodiment of this invention. The flowchart which shows the flow until a simulated X-ray image is displayed by the simulated X-ray image generation apparatus shown in FIG. The functional block diagram which shows the simulation X-ray image generation apparatus of the X-ray diagnostic apparatus which concerns on the 8th Embodiment of this invention. The flowchart which shows the flow until a simulated X-ray image is displayed by the simulated X-ray image generation apparatus shown in FIG. The functional block diagram which shows the simulation X-ray image generation apparatus of the X-ray diagnostic apparatus which concerns on the 9th Embodiment of this invention. 20 is a flowchart showing a flow until a simulated X-ray image is displayed by the simulated X-ray image generation apparatus H shown in FIG. The functional block diagram which shows the simulation X-ray image generation apparatus of the X-ray diagnostic apparatus which concerns on the 10th Embodiment of this invention. The flowchart which shows the flow until a simulated X-ray image is displayed by the simulated X-ray image generation apparatus shown in FIG. The block diagram of the conventional X-ray diagnostic apparatus used for IVR.

Explanation of symbols

20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 20H, 20I X-ray diagnostic apparatus 21 X-ray generation source 22 X-ray detector 23 bed 24 bed control section 25 C-arm type stand 26 stand control section 27 high Voltage generator 28 System controller 29 Input device 30 Monitor 31 Image processing unit 32 Image storage units 33, 33A, 33B, 33C, 33D, 33E, 33F, 33G, 33H, 33I Simulated X-ray image generation device 34 Network 35 Three-dimensional image Diagnostic device 36 3D image server 40 3D image acquisition unit 41 Constituent element database 42 Segmentation unit 43 Constituent element allocation unit 44 Scattering cross section acquisition unit 45 X-ray information conversion unit 46 Energy-specific simulated direct line image generation unit 46A First Energy-specific simulated direct line image generation unit 46B Second energy-specific Pseudo direct line image generation unit 47 Direct line addition image generation unit 47A First direct line addition image generation unit 47B Second direct line addition image generation unit 48 Image level adjustment / gamma conversion unit 49 Simulated X-ray image display processing unit 50 Positioning unit 60 Deformation correcting unit 70A First simulated X-ray image generating unit 70B Second simulated X-ray image generating unit 80 Energy-specific simulated scattered ray image generating unit 81 Scattered ray added image generating unit 82 Mixed image generating unit 90 Projection Direction changing unit 91 Field of view changing unit 92 Input device 100 Interesting organ emphasis specifying unit 110 Region of interest specifying unit 120 Electrocardiograph 121 ECG synchronization unit P Subject

Claims (15)

Storage means for storing three-dimensional image data of the subject;
Simulated X-ray image generation means for generating a simulated X-ray image projected on the detection surface of the X-ray detector of the virtual X-ray diagnostic apparatus considering a plurality of X-ray energies based on the three-dimensional image data; ,
X-ray image collection means for collecting an X-ray image of the subject by performing X-ray imaging for correcting the simulated X-ray image;
Correction means for obtaining a positional deviation amount between the X-ray image and the simulated X-ray image, and correcting the simulated X-ray image based on the positional deviation amount;
Display means for displaying the X-ray image and the corrected simulated X-ray image;
Have
The simulated X-ray image generation means includes:
Assign organ attribute information to each voxel in the 3D image data,
Based on the attribute information of the organ, assign the element X-ray absorption characteristics to each voxel,
An X-ray diagnostic apparatus, characterized in that the simulated X-ray image is generated based on an X-ray energy spectrum obtained from imaging conditions and the X-ray absorption characteristics assigned to each voxel. Storage means for storing three-dimensional image data of the subject;
Simulated X-ray image generation means for generating a simulated X-ray image projected on the detection surface of the X-ray detector of the virtual X-ray diagnostic apparatus considering a plurality of X-ray energies based on the three-dimensional image data; ,
X-ray image collection means for collecting an X-ray image of the subject by performing X-ray imaging for correcting the simulated X-ray image;
Correction means for obtaining a positional deviation amount between the X-ray image and the simulated X-ray image, and correcting the simulated X-ray image based on the positional deviation amount;
Display means for displaying the X-ray image and the corrected simulated X-ray image;
Have
The simulated X-ray image generation means includes:
Assign organ attribute information to each voxel in the 3D image data,
Based on the attribute information of the organ, element configuration information indicating the configuration of the element is assigned to each voxel in the three-dimensional image data from the composition information of the elements constituting the organ,
Assigning an X-ray absorption characteristic to each voxel in the three-dimensional image data based on the element configuration information and an X-ray absorption characteristic of the element;
Obtaining an X-ray energy spectrum used for the X-ray imaging and a projection direction of the X-ray;
The X-ray diagnostic apparatus, wherein the simulated X-ray image is generated according to the X-ray energy spectrum, the X-ray projection direction, and the X-ray absorption characteristics assigned to each voxel.   The simulated X-ray image generation means includes a spectrum distributed equally to an X-ray spectrum obtained from an imaging condition in the X-ray imaging and a spectrum distributed on a lower energy side than the X-ray spectrum obtained from the imaging condition. The X-ray diagnostic apparatus according to claim 1, wherein the simulated X-ray image is generated using any one of the spectra.   The simulated X-ray image generation means is based on a spectrum having an average energy equivalent to an average energy of an X-ray spectrum obtained from an imaging condition in the X-ray imaging and an average energy of the X-ray spectrum obtained from the imaging condition. The X-ray diagnostic apparatus according to claim 1, wherein the simulated X-ray image is generated using any one of the spectra having a smaller average energy.   3. The X-ray image generation unit according to claim 1, wherein the simulated X-ray image generation unit is configured to match the simulated X-ray image so that the degree of coincidence with the X-ray image is sufficient. Line diagnostic equipment.   The simulated X-ray image generation means performs matching involving at least one of translation, rotation, projection direction change, and warp of the simulated X-ray image so that the degree of coincidence with the X-ray image is sufficient. The X-ray diagnostic apparatus according to claim 1, wherein the X-ray diagnostic apparatus is configured as described above.   The simulated X-ray image generation means creates a simulated X-ray image for matching from the X-ray spectrum obtained from the imaging conditions in the X-ray imaging, and the X-ray spectrum obtained from the imaging conditions in the X-ray imaging Corrects the position of the simulated X-ray image obtained from another spectrum by using correction information indicating a condition for sufficient matching between the simulated X-ray image for matching and the X-ray image. The X-ray diagnostic apparatus according to claim 1, wherein the X-ray diagnostic apparatus is configured.   The simulated X-ray image generation means creates the simulated X-ray image by adding the scattered ray component of the X-ray and the direct ray component at a predetermined mixing ratio, and has a degree of coincidence with the X-ray image. The X-ray diagnostic apparatus according to claim 1, wherein the simulation X-ray image is matched so as to be sufficient.   The simulated X-ray image generation means creates a simulated X-ray image for matching by adding the scattered ray component of the X-ray and the direct ray component at a predetermined mixing ratio, and is created only from the direct ray component. The position of the simulated X-ray image is corrected using correction information indicating a condition for the degree of coincidence between the simulated X-ray image for matching and the X-ray image to be sufficient. The X-ray diagnostic apparatus according to claim 1 or 2.   3. The simulated X-ray image generation means is configured to create the simulated X-ray image using the changed projection direction when an instruction to change the projection direction is given. The X-ray diagnostic apparatus described.   The simulated X-ray image generation means is configured to calculate at least one of a composition, a density and an absorption coefficient of an element constituting at least one of an organ of interest and an organ of no interest at a predetermined ratio in the calculation of the simulated X-ray image. The X-ray diagnostic apparatus according to claim 1, wherein the X-ray diagnostic apparatus is configured to create a simulated X-ray image in which the contrast of the organ of interest is enhanced by increasing or decreasing.   The simulated X-ray image generation means is configured to calculate the simulated X-ray image so that pixels on the simulated X-ray image corresponding to a specified voxel on the three-dimensional image data are emphasized in the calculation of the simulated X-ray image. The X-ray diagnosis apparatus according to claim 1, wherein the X-ray diagnosis apparatus is configured to generate an image. The simulated X-ray image generating means is configured to generate a plurality of simulated X-ray images for each electrocardiographic phase from the three-dimensional image data collected under electrocardiographic synchronization,
The said display means is comprised so that the simulation X-ray image of the same phase as the electrocardiographic phase of the X-ray image image | photographed under the electrocardiogram synchronization may be displayed at the same timing. X-ray diagnostic equipment.   The X-ray diagnostic apparatus according to claim 1, wherein the three-dimensional image data is data collected by an image diagnostic apparatus other than the X-ray diagnostic apparatus. Storage means for storing three-dimensional image data of the subject;
Simulated X-ray image generation means for generating a simulated X-ray image projected on the detection surface of the X-ray detector of the virtual X-ray diagnostic apparatus considering a plurality of X-ray energies based on the three-dimensional image data; ,
X-ray image collection means for collecting an X-ray image of the subject by performing X-ray imaging;
Display means for displaying the X-ray image and the simulated X-ray image;
The simulated X-ray image generation means includes:
An organ assignment unit for assigning organ attribute information to each voxel in the three-dimensional image data;
Based on the attribute information of the organ, a constituent element assigning unit that assigns element constituent information indicating the constituent of the element to each voxel in the three-dimensional image data from the composition information of the element constituting the organ;
An absorption characteristic assigning unit for assigning an X-ray absorption characteristic to each voxel in the three-dimensional image data based on the element configuration information and an X-ray absorption characteristic of the element;
An imaging condition acquisition means for acquiring an X-ray energy spectrum used for the X-ray imaging and a projection direction of the X-ray;
An image generation unit that generates the simulated X-ray image according to the X-ray energy spectrum, the X-ray projection direction, and the X-ray absorption characteristics assigned to each voxel;
An X-ray diagnostic apparatus comprising:

Images