JP2008200103A - Bone disease evaluation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the high accuracy in the quantitative diagnosis for measuring the degree of bone decomposition. <P>SOLUTION: The bone disease evaluation system comprises: a detector for detecting a phase contrast image of the transmitting radiation irradiating a bone from a radiation source; a concerned region setting part for setting a concerned region from the phase contrast image detected by the detector; and a direction determining part for determining the direction of profiling the bone from the concerned region. The bone disease evaluation system also comprises: a profile acquisition part for acquiring a radiation signal intensity profile in the concerned region; a bone/flesh border determining part for determining the border between the bone and the flesh from the radiation signal intensity profile; and an evaluation part for computing an angle index indicating the angle made by the radiation signal intensity profile of the bone/flesh border. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bone disease evaluation system, and more particularly to a bone disease evaluation system for evaluating the degree of bone disease.

Currently, early detection of urns as a kind of bone disease is desired. Osteotomy is a disease that occurs because the periosteum that has proliferated erodes cartilage and bone, and is a symptom in which the surface of the bone becomes worm-like and scaly. For this reason, for example, as shown in Patent Document 1, it is conceivable to apply a diagnostic device or the like that sets a region of interest in a desired bone joint shape and quantitatively evaluates the bone joint to the diagnosis of an urn.
JP 2004-57804 A

However, since the diagnostic apparatus described in Patent Document 1 is a diagnostic apparatus mainly for evaluating rheumatic diseases, it has been difficult to evaluate the degree of urn with high accuracy.
Therefore, an object of the present invention is to make it possible to realize quantitative diagnosis accuracy for measuring the degree of urn with high accuracy.

The bone disease evaluation system in the invention of claim 1 comprises:
A radiation source that emits radiation;
A subject table for supporting a subject including bones at a position facing the radiation source;
A detector that is arranged in front of the radiation direction of the radiation on the object table, and that detects a phase contrast image of the radiation irradiated and transmitted from the radiation source to the bone;
A region-of-interest setting unit that sets a region of interest from the phase contrast image detected by the detector;
A direction determining unit that determines the profile direction of the bone from the region of interest;
A profile acquisition unit that acquires a radiation signal intensity profile in the region of interest based on the profile direction determined by the direction determination unit;
From the radiation signal intensity profile obtained by the profile acquisition unit, the bone boundary determination unit for determining the bone boundary part,
And an evaluation unit that calculates an angle index value that represents an angle formed by the radiation signal intensity profile of the bone boundary determined by the bone boundary determination unit.

The invention according to claim 2 is the bone disease evaluation system according to claim 1,
The subject is a hand.

The invention according to claim 3 is the bone disease evaluation system according to claim 1 or 2,
A storage unit for storing an evaluation result by the evaluation unit;
A comparison display unit for comparing and displaying the past evaluation result stored in the storage unit and the evaluation result currently obtained by the evaluation unit is provided.

The invention according to claim 4 is the bone disease evaluation system according to any one of claims 1 to 3,
A storage unit for storing an evaluation reference value serving as a reference in the evaluation by the evaluation unit;
A comparison display unit that compares and displays the evaluation reference value stored in the storage unit and the evaluation result currently obtained by the evaluation unit is provided.

  The present inventor has found a correlation between an angle index value representing an angle formed by a radiation signal intensity profile at a bone-and-mesh boundary and an advancement degree of an urn. Thus, as in the present invention, by calculating an angle index value that represents an angle formed by the radiation signal intensity profile at the bone-and-bone boundary part, it is possible to quantitatively diagnose the degree of progression of the calcaneus. As a result, quantitative diagnosis accuracy of the urn can be improved as compared with the prior art.

  Hereinafter, an embodiment of a bone disease evaluation system 100 according to the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

  In FIG. 1, the structural example of the bone disease evaluation system 100 in this embodiment is shown. In the present embodiment, the bone disease evaluation system 100 performs a radiographic image capturing apparatus 1 that generates an image to be imaged by irradiating X-rays that are radiation, image processing of an image generated by the radiographic image capturing apparatus 1, and the like. The image processing apparatus 30 is configured to include an image output apparatus 50 that displays an image or the like that has been subjected to image processing or the like by the image processing apparatus 30 or outputs a film. Each apparatus includes, for example, a switching hub (not shown). Via a communication network (hereinafter simply referred to as “network”) N such as a LAN (Local Area Network).

  Note that the configuration of the bone disease evaluation system 100 is not limited to the one exemplified here. For example, the image processing device 30 and the image output device 50 are integrated and image processing and image processing are performed by one device. You may comprise so that the output (display or film output etc.) of an image may be performed.

First, the radiation image capturing apparatus 1 will be described with reference to FIGS.
2 and 3 show a configuration example of the radiographic image capturing apparatus 1. In the radiographic imaging apparatus 1, a support base 3 is provided so as to be movable up and down with respect to the support base 2. An imaging device main body 4 is supported on the support base 3 via a support shaft 5 so as to be rotatable in the CW direction and the CCW direction. The support base 3 is provided with a drive device 6 that drives its elevation and rotation of the support shaft 5. The drive device 6 includes a known drive motor (not shown). The support base 3 and the imaging device main body 4 are moved up and down according to the position of the subject H. The position of the subject H can be adjusted to a position at which the subject can take a posture in which his / her arm is placed on a subject table 14 (to be described later) and does not get tired.

  The imaging device main body 4 is provided with a holding member 7 along the vertical direction. An X-ray source 8 as a radiation source according to the present invention that emits radiation to the subject H at a low tube voltage is attached to the upper portion of the holding member 7. A power supply unit 9 for applying a tube voltage and a tube current is connected to the X-ray source 8 via a support shaft 5, a support base 3, and an imaging apparatus main body unit 4. A diaphragm 10 for adjusting the radiation irradiation field is provided at the radiation emission port of the X-ray source 8 so as to be freely opened and closed. Further, the focal diameter of the X-ray source 8 is changed in accordance with an imaging method described later.

The X-ray source 8 is preferably a rotary anode X-ray tube. In this rotary anode X-ray tube, X-rays are generated when an electron beam emitted from the cathode collides with the anode. This is incoherent (incoherent) like natural light, and is not divergent X-rays but divergent light. If the electron beam continues to hit the place where the anode is fixed, the anode is damaged by the generation of heat. Therefore, in an X-ray tube that is usually used, the anode is rotated to prevent the anode from being shortened. An electron beam is made to collide with a surface of a certain size of the anode, and the generated X-rays are emitted toward the subject H from the plane of the certain size of the anode. The size of the plane viewed from the irradiation direction (subject direction) is called a focus. The focal diameter D (μm) is the length of one side when the focal point is a square, the long side or the short side when the focal point is a rectangle or a polygon, and the diameter when the focal point is a circle. Sure. In general, the larger the focal diameter D, the more radiation dose can be irradiated.
In the present embodiment, the anode of the X-ray tube is a tungsten anode with a low low energy component that does not contribute to the formation of a radiation image. This is usually used for general medical imaging, and enables radiography with a relatively low exposure dose.

In the radiographic imaging apparatus 1 of the present embodiment, when obtaining a radiographic image of a finger, the tube voltage is adjusted and applied to the X-ray source 8 so that the energy amount is within a range of 23 keV to 30 keV. Here, the X-ray source 8 preferably has an intrinsic filtration of IEC 60522-1976 standard of 2.5 mm aluminum equivalent or more, and the use of a tungsten anode is used to calculate an index indicating the degree of bone joint disease. It is more preferable in obtaining a phase contrast radiation image that can be endured. The tube voltage applied to the X-ray source 8 is preferably 25 kVp or more and 39 kVp or less. If the tube voltage is too low, the irradiated X-rays are all absorbed by the bone of the subject, and the transmitted X-ray dose necessary for measurement cannot be obtained. On the other hand, if the tube voltage is too high, the obtained object contrast becomes low, so that the measurement accuracy is deteriorated.
By setting the tube voltage in this way, it is possible to take an image with X-rays of 23 keV to 30 keV.
X-ray energy can be obtained at a tube voltage of 30 kVp for 23 keV x-ray energy and 39 kVp for 30 keV, for example, for a tungsten anode with 2.5 mm aluminum equivalent of IEC 60522-1976 standard filtration. Can do.

Below the holding member 7 and on the lower surface of the detector holding unit 12, a radiation dose detection unit 13 for detecting the irradiated radiation dose is provided.
The structure of the detector 11 will be described with reference to FIG. 4 by taking an FPD (flat panel detector) as an example. FIG. 4 is a perspective view of the detector 11. The detector 11 includes a housing 61 that protects the inside, and is configured to be portable as a cassette.
An imaging panel 62 that converts irradiated radiation into an electrical signal is formed in layers inside the casing 61. A light emitting layer (not shown) that emits light according to the intensity of the incident radiation is provided on the radiation irradiation side of the imaging panel 62.
The light emitting layer is generally called a scintillator layer. For example, a phosphor is a main component, and based on incident radiation, an electromagnetic wave having a wavelength of 300 nm to 800 nm, that is, visible light to ultraviolet light to infrared light. Output electromagnetic waves (light).
The electromagnetic wave (light) output from the light emitting layer is converted into electric energy and accumulated on the surface opposite to the surface on which the radiation of the light emitting layer is irradiated, and an image signal based on the accumulated electric energy is stored. A signal detection unit 600 in which photoelectric conversion units that perform output are arranged in a matrix is formed. Note that a signal output from one photoelectric conversion unit is a signal corresponding to one pixel serving as a minimum unit constituting the radiation image data. The signal detection unit 600 takes out the stored electric energy as an electric signal by switching, amplifies the electric signal at a predetermined amplification rate (gain), and then converts the electric signal into digital data. In this way, radiation image data is created by the imaging panel 62.

  Below the holding member 7 and on the lower surface of the detector holding unit 12, a radiation dose detection unit 13 for detecting the irradiated radiation dose is provided.

  Between the X-ray source 8 and the detector holding unit 12, a plate-like subject table 14 that holds the subject's finger as the subject H from below is provided so that one end thereof is attached to the holding member 7. ing. The subject table 14 is connected to a position adjustment device 15 including a motor or the like that changes the position relative to the holding member 7 in order to adjust the shooting magnification (position adjustment in the height direction) during phase contrast shooting.

The subject table 14 is formed so as to protrude from the other end of the detector holding unit 12 toward the subject. Above the subject table 14, a compression plate 21 for compressing and fixing the subject H from above is provided so that one end thereof is attached to the holding member 7. The compression plate 21 is movable along the holding member 7. The movement of the compression plate 21 can be applied either automatically or manually. The end surface on the subject side of the compression plate 21 is disposed so as to slightly protrude toward the subject side from the X-ray source 8 and the detector 11 (effective image end surface) disposed in a substantially vertical direction. Therefore, it is preferable that the imaging target range (for example, the right hand) of the subject is arranged so as to be positioned closer to the holding member 7 than the compression plate 21 without causing image loss in the region of interest (imaging target range). In addition, it is preferable that the end surface of the subject table 14 has a curved shape so that an elderly subject having an average body shape can sit on the chair X and put the upper body on the subject table 14.
Further, in the present embodiment, a protector 25 is provided on the lower surface of the subject table 14 so as to extend in a substantially vertical direction so that the subject can take a shooting position without hitting his / her leg. . Thus, the subject can sit at the imaging position without sitting on the detector holding unit 12 while sitting on the chair X. Moreover, it is possible to prevent a part of the patient's body from entering the X-ray irradiation region and receiving unnecessary exposure. Note that the compression plate and the protector 25 are not essential components, and the compression plate and the protector 25 may not be used.

As shown in FIG. 5, the subject table 14 includes a hand holding unit 16 that holds the finger of the subject so as to intersect the radiation irradiation path. The size of the hand holding unit 16 is not particularly limited as long as the subject's fingers can be placed thereon. On the upper surface of the hand holding unit 16, a triangular magnet 17 is provided that is disposed between the thumb and the index finger while the subject puts his / her finger on the hand holding unit 16. The hand holding unit 16 is provided with photographing direction discriminating means 18 (see FIG. 6) for detecting the placement location of the triangular magnet 17 and discriminating the position of the subject's thumb as photographing direction information.
Here, the irradiation field Q at the time of hand bone joint imaging is set in advance so that two phalanges sandwiching the joint can be accommodated (see FIG. 5). This is an analysis value that can sufficiently withstand follow-up even if it is an image of one joint by acquiring a radiographic image with high sharpness and low tube voltage phase contrast at the time of bone joint imaging as described later Is obtained.

  As shown in FIG. 6, the photographing apparatus main body 4 includes a control device 22 including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The control device 22 is connected with a radiation dose detection unit 13, a power supply unit 9, a drive device 6, a position adjustment device 15, an information supplement unit 26, an imaging direction determination unit 18, and a detector identification unit 29 via a bus 23. Yes. The control device 22 includes an input device 24a including a keyboard and a touch panel (not shown) for inputting photographing conditions and the like, a position adjustment switch for adjusting the position of the subject table 14, and a CRT display, a liquid crystal display, and the like. The operation device 24 having the display device 24b is connected. In addition, the imaging apparatus main body 4 may be provided with information acquisition means for acquiring patient information and the like by reading a barcode and the like.

  The ROM of the control device 22 stores a control program and various processing programs for controlling each part of the radiographic image capturing device 1, and the CPU cooperates with the control program and various processing programs in the radiographic image capturing device. (1) It functions as an image data generation unit that performs overall control of operations of each unit, performs phase contrast imaging, and generates image data of a phase contrast image.

  For example, the CPU controls the driving device 6 based on the determination result by the imaging direction determination means 18, the imaging conditions of the subject, and the like so that the imaging device body 4 matches the height of the subject. The support shaft 5 is rotated to adjust the radiation irradiation angle. Then, the position of the subject table 14 is adjusted by the position adjusting device 15 to adjust the magnification of phase contrast imaging. Thereafter, the imaging apparatus main body unit 4 performs imaging processing, and the power source unit 9 applies a tube voltage to the X-ray source 8 to irradiate the subject H with radiation, which is input from the radiation dose detection unit 13. When the radiation dose reaches a preset radiation dose, the power supply unit 9 stops radiation from the X-ray source 8. Alternatively, X-ray irradiation conditions may be set in advance, and X-rays may be irradiated under those conditions.

  As described above, the shooting direction information acquired by the shooting direction determination unit 18 and the left / right information input from the input device 24a are output to the information supplementary unit 26 via the control unit 22. In the present embodiment, patient information (photographed person information) regarding the subject H, information such as the date and time of photographing (information at the time of photographing), and the photographed subject H are obtained from the operation device 24 or information acquisition means (not shown). The part information related to the imaging part indicating which part of the patient is to be inputted is inputted, and the inputted information is outputted to the information supplement means 26 via the control device 22. In the case where the control device 22 has a timer function, the control device 22 automatically acquires the shooting time when shooting is performed without inputting the shooting time information again, and the shooting time is set. The information may be output to the information ancillary means 26 as shooting time information to be attached to the image data.

  The information supplementary means 26 associates these pieces of information (imaging direction information, left / right information, subject information, imaging information, part information, etc.) as supplementary information with the image data of the generated phase contrast image. ing. Note that the supplementary information attached to the image data by the information supplementary means 26 is not limited to this. For example, patient (photographed person) ID information and the like may be attached. Moreover, the information supplementary means 26 is not limited to supplementing all the information exemplified here, and any of these pieces of information may be supplemented.

  The detector identification unit 29 is built in the detector holding unit 12, and the detector 11 set in the detector holding unit 12 is for normal imaging, phase contrast imaging, or high magnification. It is used to identify whether it is for phase contrast photography. Specifically, the detector identifying unit 29 identifies by reading an identification mark (uneven portion) provided on the housing or the like of the detector 11, a conduction unit, an RFID, a barcode, and the like. Then, the detector identifying unit 29 determines, for example, whether or not it is suitable for radiography to be performed in the future compared with imaging conditions input from the operation device 24, and the identification result is determined by the control device 22. Output to. If the identification result is incompatible, the control device 22 controls the display device 24b to display a warning. That is, in this embodiment, the notification unit according to the present invention is the display device 24b. Note that the notification unit may be an audible notification instead of a visual notification.

  In addition, the control device 22 controls each unit so that normal imaging, phase contrast imaging, and high magnification phase contrast imaging are executed in response to an imaging switching instruction to the input device 24a.

Here, normal photographing is a photographing condition in which the subject H is brought into close contact with the detector 11, which is generally performed. In this case, the control device 22 sets the compatible detector to “normal imaging” so that the detector 11 for normal imaging is mounted.
In phase contrast imaging for imaging a wide range of hands, the focal diameter D of the X-ray source 8 is 0 so that phase contrast imaging is executed with an enlargement factor M described later corresponding to 1.5 to 3 times. 0.1 mm, the average radiation energy is 26 keV. Further, in the phase contrast imaging, the ratio of the signal value output from the detector 11 to the radiation dose (dose) irradiated to the detector 11 is set to be moderately higher than that in the normal imaging. This is because, for example, the distance between the X-ray tube and the detector is increased, and the average radiation energy is decreased, so that the X-ray dose reaching the detector 11 is decreased.

  In order to increase the ratio of the signal value output from the detector 11 to the dose of irradiated radiation, the highly sensitive detector 11 is selected and mounted on the detector holding unit 12 or the detector. For example, a method of increasing the amplification ratio (gain) of the signal output from 11 or combining them can be considered. In order to increase the sensitivity of the detector 11, for example, the stimulable phosphor sheet accommodated in the detector 11 or the light emitting layer used for the imaging panel 62 emits light with high luminance even at a low radiation dose. To. In order to increase the gain, for example, the amplification ratio of the electric signal in the signal detection unit 600 is increased, or the photostimulable phosphor sheet irradiated with radiation is read and radiation image data is output. In the reading device, the amplification ratio of the electrical signal read from the photostimulable phosphor sheet is increased. Moreover, you may make it raise the ratio which amplifies the radiographic image data output from the detector 11 or the reader. In the present embodiment, the control device 22 sets the suitable detector to “for phase contrast imaging” so that the detector 11 for phase contrast imaging having higher sensitivity and higher gain than the detector 11 for normal imaging is mounted. It is said. This phase contrast imaging is applied to quantitative diagnosis of osteoporosis. On the other hand, in high-magnification phase-contrast imaging applied in quantitative bone and joint deformation diagnosis for rheumatic diseases, phase-contrast imaging is performed with the magnification factor M corresponding to 3 to 10 times. The focal diameter D of the X-ray source 8 is 0.05 mm, and the average radiation energy is 23 keV. Furthermore, in high magnification phase contrast imaging, both sensitivity and gain are higher than in phase contrast imaging. That is, the control device 22 sets the compatible detector to “for high magnification phase contrast imaging” so that the detector 11 for high magnification phase contrast imaging is mounted. This is because in high magnification phase contrast imaging, the subject H and the detector 11 are separated from each other and the average radiation energy is low.

  Next, a phase contrast imaging method will be described. FIG. 7 is a diagram for explaining the outline of phase contrast imaging. As shown in FIG. 7, in the case of a normal photographing method, the subject H is disposed at a position where the detector 11 is in contact with the subject H (contact photographing position in FIG. 7). In this case, the X-ray image (latent image) recorded in the detector 11 is substantially the same size as the life size (which means the same size as the subject H).

  On the other hand, phase contrast imaging provides a distance between the subject H and the detector 11, and X-rays expanded with respect to the life size by X-rays emitted from the X-ray source 8 in a cone beam shape. A latent image of an image (hereinafter referred to as an enlarged image) is detected by the detector 11.

Here, the enlargement ratio M with respect to the life size of the enlarged image is determined such that the distance from the focal point a of the X-ray source 8 to the subject H is R1, the distance from the subject H to the detector 11 is R2, and from the focal point a of the X-ray source 8. If the distance to the detector 11 is L (L = R1 + R2), it can be obtained by the following equation (1).
M = L / R1 (1)

In the phase contrast enlarged image, as shown in FIG. 8, the X-ray refracted by passing through the edge of the subject H overlaps on the detector 11 with the X-ray that passes through the subject H without passing through the subject H. X-ray intensity increases. On the other hand, a phenomenon occurs in which the X-ray intensity is weakened in the portion inside the edge of the subject H by the amount of the refracted X-rays. Therefore, an edge emphasis action (also referred to as an edge effect) in which the X-ray intensity difference spreads at the border of the subject H works, and an X-ray image with high visibility in which the border portion is sharply depicted can be obtained. .
When the setting of the distance L is limited, such as in a shooting room, the distance L is fixed, and within the fixed distance L, the ratio of the distances R1 and R2 can be changed and shooting can be performed under optimum conditions. For example, when L = 3.0 (m) is determined, R1 = 1.0 (m) and R2 = 2.0 (m) are set for this distance L. Considering the size of a general photography room, the range of 0.1 ≦ R1 ≦ 2.0, 0.3 ≦ R2 ≦ 2.0, 0.8 ≦ L ≦ 3.0 is set, and the enlargement ratio M is 1. .5 ≦ M ≦ 10, and the focal diameter D is in the range of 0.005 (mm) ≦ D ≦ 0.2 (mm). The optimum distances L, R1, R2, the enlargement ratio M, and the focal diameter D may be determined. By setting the focal point diameter D in such a range, the X-ray intensity is strong, imaging can be performed for a short time, and motion blur due to movement of the subject H can be reduced. More preferable distances satisfy the ranges of 0.5 ≦ R1 ≦ 1.2, 0.5 ≦ R2 ≦ 1.2, 1.0 ≦ L ≦ 2.5, and the enlargement ratio M is 3 ≦ M ≦ 8. The focal diameter D can be set to satisfy the range of 0.03 (mm) ≦ D ≦ 0.08 (mm).
As the enlargement ratio M is higher, finer image information can be obtained, and the accuracy of the quantitative result is also higher. On the other hand, an X-ray tube with a smaller focal diameter is required for high-magnification imaging, but because the output is low and the imaging time is long, blurring due to the movement of the subject tends to occur, and the sharpness of the image quality is impaired. Therefore, the above range is optimal in reality because highly accurate analysis cannot be performed.

  Next, the image processing apparatus 30 in the present embodiment will be described with reference to FIG.

  The image processing apparatus 30 according to the present invention performs image processing on the radiographic image data generated by the radiographic image capturing apparatus 1 to generate an image suitable for diagnosis. As shown in FIG. 9, the image processing apparatus 30 includes a control unit 31, a storage unit 32, an input unit 33, a communication unit 34, an image processing unit 35, a region of interest setting unit 37, an index calculation unit 38, a direction determination unit 39, and the like. These parts are connected to each other via a bus 36.

  The control unit 31 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like (none of which are shown). Alternatively, according to various programs stored in the storage unit 32, control operations are sent to the respective units to centrally control the overall operation of the image processing apparatus 30, and various processes such as an image extraction process to be described later are executed. Yes. Note that the image processing unit 35, the region of interest setting unit 37, and the direction determination unit 39 also operate in accordance with various programs in the same manner as the control unit 31.

  The storage unit 32 includes a magnetic or optical storage medium such as an HDD (Hard Disc Drive) or an optical disk, or a storage medium (not shown) such as a semiconductor memory, which is fixed or detachable, and includes an image processing program and the like. In addition to the various programs related to 30, various data used when executing these processing programs are stored.

  In the present embodiment, the storage unit 32 stores image data of a radiographic image captured by the radiographic image capturing apparatus 1 and sent to the image processing apparatus 30. In the present embodiment, as described above, the image data of the radiographic image includes imaging direction information, left and right information, subject information, imaging information, part information, and the like by the information supplementary means 26 of the radiographic imaging device 1. The information is sent to the image processing apparatus 30 as ancillary information, and the storage unit 32 stores the information attached to the image data.

The storage unit 32 stores the evaluation reference value of the index (calculated index) calculated by the index calculation unit 38, and the control unit 31 compares the calculated index with the evaluation reference value, thereby calculating the calculated index. Evaluation is to be made.
The storage unit 32 stores a shape list of each bone.
Further, the storage unit 32 stores the patient identification information in association with the calculated index.

  The input unit 33 includes, for example, a keyboard having cursor keys, numeric input keys, and various function keys (not shown), and a pointing device such as a mouse, and can input image processing conditions and the like. . The input unit 33 outputs an instruction signal input by a key operation or a mouse operation on the keyboard to the control unit 31. When the operator operates the input unit 33, an evaluation target bone for which the evaluation of the urn is executed is designated (evaluation target bone designation instruction) from each bone shown in the phase contrast image.

  The communication unit 34 is configured by a network interface or the like, and transmits and receives data to and from external devices such as the radiographic image capturing apparatus 1 and the image output apparatus 50 connected to the network N via a switching hub. That is, the communication unit 34 receives the image data of the radiographic image generated by the radiographic imaging device 1 through the network N, and the image data of the image that has been subjected to image processing to an external device such as the image output device 50 as appropriate. Is to send.

The region-of-interest setting unit 37 sets a region for calculating an index from the phase contrast image of the evaluation target bone B1. When an evaluation target bone designation instruction is input from the operator to the input unit 33, the region-of-interest setting unit 37 specifies an evaluation target bone from each bone in the phase contrast image based on the content of the instruction, and its shape Recognize Specifically, when the hand phase contrast image G1 is acquired as shown in FIG. 10A, the region-of-interest setting unit 37 recognizes the shape of the evaluation target bone B1 in the image. In this recognition method, as shown in FIG. 10B, for example, a bone part and a meat part are discriminated from a radiation signal intensity profile to follow the edge of the evaluation target bone B1 and recognize the shape. After the shape recognition, the recognized shape is compared with the shape list of each bone in the storage unit 32 to recognize the shape and orientation of the evaluation target bone B1.
There are various methods of setting the region of interest. For example, the region of interest can be set by specifying a rectangular frame by the input unit 33, or can be automatically set by performing image analysis on the radiation image. When setting automatically, it must be set so that the edge of the evaluation target bone B1 is at least within the region of interest. For example, as shown in FIG. 11, a rectangular frame is specified around a predetermined position P1 on the edge of the evaluation target bone B1 in the phase contrast image, and the inside of the rectangular frame is set as a region of interest R.

  When the region of interest R is set by the region of interest setting unit 37, the direction determining unit 39 determines the profile direction of the evaluation target bone B1 from the region of interest R. Specifically, as shown in FIG. 11, the profile direction includes a direction H1 from the outside toward the center of gravity P2 while intersecting the edge of the evaluation target bone B1, a direction H2 orthogonal to the edge of the evaluation target bone B1, and the like. .

  The index calculation unit 38 calculates an index representing the degree of calcaneus of the evaluation target bone B1 in the region of interest R, and includes a profile acquisition unit 40, an evaluation unit 41, a bone boundary determination unit 42, and the like.

The profile acquisition unit 40 acquires a radiation signal intensity profile in the region of interest R based on the profile direction determined by the direction determination unit 39. Specifically, as shown in FIG. 12, the profile acquisition unit 40, based on the radiation signal intensity in the region of interest R in the phase contrast image, in the profile direction (in FIG. 12, the profile direction and the lateral direction of the region of interest R). The radiation signal intensity profile is acquired. A plurality of signal intensity profiles are obtained from the region of interest R at equal intervals K.
In the present embodiment, one line of actually measured radiation signal intensity profile is used as one line of radiation signal intensity profile when determining a bone-and-bone boundary portion described later. The average value of the radiation signal intensity profile for one line may be used as the radiation signal intensity profile for one line when determining the bone / middle boundary. When averaged in this way, a bone boundary part can be determined with a radiation signal intensity profile with reduced noise, and the accuracy can be further improved.

  The bone and meat boundary determination unit 42 determines the bone and meat boundary portion from the radiation signal intensity profile obtained by the profile acquisition unit 40. FIG. 13 is a diagram illustrating an example of a radiation signal profile. As shown in FIG. 13, in the radiation signal intensity profile F, there is a difference in signal value between the flesh-side profile F1 and the bone-side profile F2, and during that time (bone flesh boundary F3), a steep fluctuation is shown. It is supposed to be. The bone meat boundary determining unit 42 scans the radiation signal intensity profile F from the bone side end portion f1 toward the meat side, and a point where the displacement is equal to or greater than the specified range at a predetermined position interval is set as the boundary start point P5. . In addition, the bone boundary determination unit 42 scans the radiation signal intensity profile F from the meat side end f2 toward the bone side, and the displacement per predetermined position interval on the bone side from the boundary start point P5 is within a specified range. A portion P7 that falls within is specified. The bone and meat boundary determining unit 42 sets the meat side end of the portion P7 as the boundary end point P6. The bone and meat boundary determining unit 42 determines the range from the boundary start point P5 to the boundary end point P6 as a bone boundary part.

  The evaluation unit 41 calculates an angle index value that represents an angle formed by the radiation signal intensity profile of the bone / border boundary determined by the bone / border boundary determination unit 42. The evaluation unit 41 sets various reference lines for the radiation signal intensity profile in order to detect the angle index value. For example, the evaluation unit 41 sets an approximate straight line of the radiation signal intensity profile that intersects the boundary start point P5 and is on the flesh side with respect to the boundary start point P5 as the reference line a. Further, the evaluation unit 41 sets the approximate straight line of the radiation signal intensity profile of the portion P7 that intersects the boundary end point P6 as the reference line b. Then, the evaluation unit 41 sets a line connecting the boundary start point P5 and the boundary end point P6 as the reference line c.

When setting of the reference lines a, b, and c is completed, the evaluation unit 41 calculates an angle index value based on the reference lines a, b, and c. The angle index value may be any value as long as it represents an angle formed by the radiation signal intensity profile, and examples thereof include the following. FIG. 14 is an explanatory diagram showing the types of angle index values. As shown in FIG. 14A, the acute angle d2 formed by the reference line a and the reference line c, the obtuse angle d1, or the acute angle d3 formed by the reference line b and the reference line c, and the obtuse angle d4 are used as angle index values. Also good. Further, as shown in FIG. 14B, an interval L1 between the boundary start point p5 and the boundary end point P6 may be used as the angle index value. And as shown in FIG.14 (c), it is good also considering the signal value width | variety S and profile length Y when it moves to the bone side by the prescribed distance X from the boundary start point P5 as an angle index value. As shown in FIG. 14 (d), the starting point of the specified distance X may be anywhere on the radiation signal intensity profile of the bone boundary portion, not the boundary starting point P5.
In the present embodiment, the evaluation unit 41 calculates an acute angle d3 formed by the reference line b and the reference line c in FIG. 14A as an angle index value.

  When the angle index value is calculated from all the radiation signal intensity profiles acquired from the region of interest R, the evaluation unit 41 calculates a representative value in the region of interest R. Specifically, the average value of the angle index values acquired from each radiation signal intensity profile is used as a representative value.

  When the representative value is determined, the evaluation unit 41 evaluates the representative value. Here, FIG. 15 is an explanatory diagram comparing and displaying the bone state of a healthy person and the bone state of an urn patient. FIG. 15A shows the trabecular state of each of a healthy person and an urn patient. As shown in FIG. 15 (a), it can be seen that trabecular bone is reduced in the patient with an osteotomy. On the other hand, FIG. 15 (b) shows the state of the bone edge of each of a healthy person and an urn patient. As shown in FIG. 15 (b), in an osteoporosis patient, the bone margin is not clear and the line is broken. For these reasons, when the radiation signal intensity profile of the bones of a healthy person is compared with the radiation signal intensity profile of an osteoporosis patient, the angle at the bone boundary becomes smaller in the osteoporosis patient (see FIG. 16). 16 is a bone boundary portion around the right side of the boundary start point.

FIG. 17 is a comparison of representative values of angle index values in 15 healthy subjects and 15 antique patients. The circles in the figure are average values of 15 people. Further, when the angle index value is obtained, the radiation signal intensity profile is graphed. In this case, the ratio of the vertical axis scale and the horizontal axis scale is the same for both healthy subjects and patients with osteoarthritis. The ratio of the vertical scale and the horizontal scale of the radiation signal intensity profile when obtaining the angle of FIG. 17 is vertical axis (signal value [tone]) / horizontal axis (distance [mm]) = 80.
As shown in FIG. 17, the representative value of the angle index value is 30 degrees for a healthy person, but is about 17 degrees smaller than that for a healthy person. Therefore, in the present embodiment, for example, 20 degrees is stored in the storage unit 32 as the evaluation reference value in the representative value of the angle index value, and the evaluation unit 41 calculates the calculated index (angle index) calculated by the index calculation unit 38. The representative value of the value) and the evaluation reference value stored in the storage unit 32 are compared to evaluate the degree of urn in the region of interest R of the evaluation target bone B1.

For example, when determining the degree of urns for the subject whose past calculation index is stored in the storage unit 32, the evaluation unit 41 reads the past calculation index from the storage unit 32, and calculates the calculation. It is determined that the index and the calculated index calculated this time are displayed in comparison.
On the other hand, when determining the degree of urns for a subject whose past calculation index is not stored in the storage unit 32, the control unit 31 stores the evaluation reference value (in this embodiment, the angle in the embodiment). An index value evaluation reference value of 20 degrees) is read out, and it is determined that the evaluation reference value and the calculated index obtained this time are displayed in comparison.

  Note that the evaluation reference value is obtained from experiments, simulations, analysis of past data, and the like so that the initial symptoms of the urn can be determined. In this case, when obtaining the angle serving as the evaluation reference value, the aspect ratio (ratio of the vertical scale to the horizontal scale in the graph) equivalent to the radiation signal intensity profile plotted by the image processing device 30 is used. It is a premise.

  And based on the determination result of the evaluation part 41, the control part 31 makes the display part of the image output device 50 mentioned later display according to the determination result, or make the film output according to the determination result. It is supposed to be. In this case, the image output apparatus 50 compares and displays the past evaluation results stored in the storage unit 32 and the evaluation results currently obtained by the evaluation unit 41, or the evaluation criteria stored in the storage unit 32. It is a comparison display part concerning the present invention which compares and displays a value and the evaluation result currently calculated by evaluation part 41.

The image processing unit 35 performs image processing such as gradation processing for adjusting the contrast of the image, processing for adjusting the density, frequency processing for adjusting the sharpness, and the like on the image data of the radiation image. Thereby, it is possible to perform image processing suitable for conditions such as an imaging region.
Note that image processing parameters that define image processing conditions corresponding to conditions such as an imaging region, an imaging condition, and an imaging direction are stored in advance in the storage unit 32 and the like. The image processing unit 35 reads out the corresponding image processing parameters from the storage unit 32 in accordance with information attached to the image data such as the imaged region, the imaging direction, or the like. It is preferable to determine image processing conditions based on the read parameters. Note that when the image data does not include information such as the imaged part and the imaging direction, necessary conditions may be input from the input unit 33 or the like, and image processing may be performed based on this.

  Next, the image output device 50 prints (film outputs) image data on a monitor (display unit) such as a CRT (Cathode Ray Tube) or LCD (Liquid Crystal Display), or on a medium such as a film or paper. An image display device, a printer, and the like configured to include an output unit such as a print unit, a communication unit for connecting to an external device, a power supply unit that supplies power (not shown), and the like. When the control unit 31 (determination unit) determines whether or not there is a change in each part between the target image and the past image, and the presence or absence of a changing part (change area), the image output device 50 It functions as an output means for outputting the determination result. The communication unit is configured by a network interface or the like, and transmits / receives data to / from an external device such as the radiation image capturing apparatus 1 or the image output apparatus 50 connected to the network N via a switching hub.

  When the communication unit 34 receives image data of a radiographic image subjected to image processing by the image processing device 30 through the network N, the image output device 50 appropriately outputs the image by the output unit (display unit or print unit). It is like that.

  Further, as described above, when the display contents are determined by the image processing device 30, for example, the fact is displayed on the display unit of the image output device 50, or the fact is clearly indicated on the film output. It has come to be.

  In the case where the image output device 50 is an image display device including a monitor (display unit), a medical image for diagnosis is displayed and used for diagnosis of a doctor or the like. Therefore, a general PC (Personal Computer) is used. It is preferable to provide a higher-definition monitor (display unit) than the above.

Next, the operation of the bone disease evaluation system 100 in the present embodiment will be described with reference to FIG.
First, when imaging order information is registered, for example, when an imaging subject (patient) performs examination registration (imaging order registration) by receiving an examination (not shown), the imaging subject is moved either left or right based on the imaging order information. The arm portion is placed on the subject table 14, and the triangular magnet 17 is placed between the thumb and the index finger (step S1).

Thereafter, the drive device 6 and the position adjustment device 15 adjust the position of the subject table 14 and the angle of the imaging device main body 4 in accordance with imaging conditions such as the radiation irradiation angle, irradiation distance, and imaging magnification. In the present embodiment, the position of the subject table 14 is adjusted so as to achieve phase contrast imaging (step S2).
In step S3, the control device 22 shifts to step S4 when the detector 11 identified by the detector identifying unit 29 does not match the conformity detector set in step S2, that is, incompatibility. If it is identified that it is for contrast photography, the process proceeds to step S5.

  In step S4, the control device 22 controls the display device 24b to display that the set detector 11 is incompatible with the main photographing, and the process is terminated.

  In step S5, after adjusting the position and angle of the subject table 14, the power supply unit 9 applies a tube voltage to the X-ray source 8 so that the average radiant energy is 26 keV, and the X-ray source 8 is applied to the subject H. Phase contrast imaging is performed by irradiating with radiation.

  When the image data of the phase contrast image is generated, shooting direction information, left / right information, subject information, shooting time information, part information, and the like are attached to the generated image data as additional information (step S6). Then, the radiographic imaging device 1 transmits the image data of the generated radiographic image together with the auxiliary information to the image processing device 30 (step S7).

  When the image processing apparatus 30 receives the image data and its accompanying information from the radiation image capturing apparatus 1 (step S8), the image processing apparatus 30 stores (stores) the received image data and its accompanying information in the storage unit 32 (step S9).

  The control unit 31 designates the bone designated by the input unit 33 as the evaluation target bone B1 (step S10).

  Thereafter, the control unit 31 controls the region-of-interest setting unit 37 to recognize the shape of the evaluation target bone B1 in the image data (step S11), and the shape of the evaluation target bone B1 and the shape in the storage unit 32 By comparing with the list, the shape and direction of the evaluation target bone B1 are specified, and the region of interest R is set (step S12).

  Then, the control unit 31 controls the direction determination unit 39 to determine the profile direction in the region of interest R (step S13).

  When the profile direction is determined, the control unit 31 controls the profile acquisition unit 40 to acquire a plurality of radiation signal intensity profiles in the profile direction in the region of interest R at predetermined intervals (step S14).

  When the radiation signal intensity profile is acquired, the control unit 31 controls the bone / mesh boundary determination unit 42 to determine the bone / border boundary part in the radiation signal intensity profile (step S15).

  Thereafter, the control unit 31 controls the evaluation unit 41 to set the reference lines a, b, c in the radiation signal intensity profile (step S16).

  The control unit 31 controls the evaluation unit 41 to calculate a calculation index (representative value of the angle index value of the radiation signal intensity profile at the bone boundary part) (step S17).

  The control unit 31 controls the storage unit 32 to store the calculated index (step S18).

  Then, the control unit 31 determines whether or not the past calculated index of the subject is stored in the storage unit 32 based on the subject information attached to the image data (step S19). When the past calculation index of the subject is stored (step S19; YES), the control unit 31 proceeds to step S20, and when not stored (step S19; NO), the control unit 31 proceeds to step S21. .

  In step S20, the control unit 31 reads a past calculated index of the subject to be imaged from the storage unit 32, determines that the calculated index and the calculated index calculated this time are displayed in comparison, and step S22. Migrate to

  In step S21, the control unit 31 reads the evaluation reference value from the storage unit 32, determines that the evaluation reference value is compared with the calculated index obtained this time, and moves to step S22.

  In step S22, the control unit 31 transmits the image data transmitted from the radiation image capturing apparatus 1, the accompanying information, the current calculation index, the evaluation reference value, the determination result, and the past calculation index, if any, to the communication unit 34. To the image output device 50.

When receiving data from the image processing device 30 (step S23), the image output device 50 causes the output unit to output the received content (step S24). As described above, the output method may be either viewer display on a monitor (display unit) or film output (hard copy) on a print unit. As a result, the image output device 50 can browse image data, supplementary information, current calculation index, evaluation reference value, comparative display based on the determination result, and past calculation index. Here, in the image output device 50, the current calculated index and the past calculated index can be compared and displayed, or the current calculated index and the evaluation reference value can be compared and displayed.
In the present embodiment, when the past calculated index of the subject is stored in step S19, only the process of step S20 is performed. However, the process of step S21 may be performed together. .

  As described above, according to the bone disease evaluation system 100 according to the present embodiment, the angle index value representing the angle formed by the radiation signal intensity profile at the bone boundary portion is calculated, thereby quantitatively diagnosing the degree of progression of the urn. Can do. As a result, quantitative diagnosis accuracy of the urn can be improved as compared with the prior art.

  Further, in the present embodiment, the radiation signal intensity profile is obtained based on the phase contrast image. This is because the difference in the radiation signal intensity is clearer in the phase contrast image than in the radiographic image obtained by normal imaging. This is because the angle index can be measured with high accuracy.

  In addition, since the subject is a hand in the present embodiment, the exposure dose is simple and less than other portions. Furthermore, since bone diseases show symptoms first from the end of the body, the use of hand bone images makes it possible to detect bone diseases earlier than the femur and spine.

  In the present embodiment, the image output device 50 compares and displays the past evaluation result stored in the storage unit 32 and the evaluation result currently obtained by the evaluation unit 41. Symptoms can be easily compared and more efficient diagnosis is possible.

  Furthermore, in the present embodiment, the image output device 50 compares and displays the evaluation reference value stored in the storage unit 32 and the evaluation result currently obtained by the evaluation unit 41. Symptoms can be easily compared and more efficient diagnosis is possible.

  In the present embodiment, the case where the image processing device 30 and the image output device 50 are provided as separate devices has been described as an example. However, the image processing unit, the storage unit, the determination unit, and the display unit as the output unit are described. Alternatively, the printing unit or the like may be provided in one apparatus, and the image processing apparatus 30 and the image output apparatus 50 may be combined into one apparatus.

It is a figure which shows the principal part structure of the bone disease evaluation system in this embodiment. It is a side view which shows the principal part structure of the radiographic imaging apparatus in this embodiment. It is a schematic diagram which shows the internal structure of the radiographic imaging apparatus in this embodiment. It is a perspective view of the detector with which the radiographic imaging device in this embodiment is equipped. It is a top view at the time of the subject putting the back of the left hand on the hand holding part in this embodiment toward the upper part. It is a block diagram which shows the control structure of the radiographic imaging apparatus in this embodiment. It is a figure explaining the outline of phase contrast photography in this embodiment. It is a figure explaining a phase contrast effect. It is a block diagram showing the control structure of the image processing apparatus in this embodiment. It is a figure which shows the example of a process with respect to the phase contrast image obtained by the radiographic imaging apparatus in this embodiment, (a) is explanatory drawing which shows an example of a phase contrast image, (b) is description which shows the procedure of a shape recognition process FIG. It is explanatory drawing showing the profile direction of the evaluation object bone in this embodiment. It is a figure showing the profile direction in the region of interest in this embodiment. It is explanatory drawing showing an example of the radiation signal intensity profile in the region of interest of FIG. It is explanatory drawing showing the kind of angle index value in this embodiment. It is explanatory drawing which compared and displayed the bone state of the healthy subject in this embodiment, and the bone state of an osteoarthritis patient, (a) represents the trabecular state of a healthy subject and an osteopathic patient respectively, (b) is a healthy subject. This represents the state of the bone margin of each patient with an urn. It is explanatory drawing which compared the radiation signal intensity profile of the osteoporosis patient in this embodiment, and the radiation signal intensity profile of a healthy subject. It is explanatory drawing which compared the representative value of the angle parameter | index value in 15 healthy persons and 15 antique patients. It is a flowchart showing the process in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radiographic imaging apparatus 2 Support stand 3 Support base 4 Imaging apparatus main-body part 5 Support shaft 6 Drive apparatus 7 Holding member 8 X-ray source (radiation source)
DESCRIPTION OF SYMBOLS 9 Power supply part 11 Detector 12 Detector holding | maintenance part 13 Radiation dose detection part 14 Subject stand 22 Control apparatus 24 Operation apparatus 29 Detector identification part 30 Image processing apparatus 31 Control part 32 Storage part 33 Input part 34 Communication part 35 Image processing part 35 37 Region of Interest Setting Unit 38 Index Calculation Unit 39 Direction Determination Unit 40 Profile Acquisition Unit 41 Evaluation Unit 42 Bone Meat Boundary Determination Unit 50 Image Output Device 100 Bone Disease Evaluation System R Region of Interest

Claims (4)

A radiation source that emits radiation;
A subject table for supporting a subject including bones at a position facing the radiation source;
A detector that is arranged in front of the radiation direction of the radiation on the object table, and that detects a phase contrast image of the radiation irradiated and transmitted from the radiation source to the bone;
A region-of-interest setting unit that sets a region of interest from the phase contrast image detected by the detector;
A direction determining unit that determines the profile direction of the bone from the region of interest;
A profile acquisition unit that acquires a radiation signal intensity profile in the region of interest based on the profile direction determined by the direction determination unit;
From the radiation signal intensity profile obtained by the profile acquisition unit, the bone boundary determination unit for determining the bone boundary part,
A bone disease evaluation system comprising: an evaluation unit that calculates an angle index value that represents an angle formed by the radiation signal intensity profile of the bone boundary determined by the bone boundary determination unit. In the bone disease evaluation system according to claim 1,
The bone disease evaluation system, wherein the subject is a hand. In the bone disease evaluation system according to claim 1 or 2,
A storage unit for storing an evaluation result by the evaluation unit;
A bone disease evaluation system comprising: a comparison display unit for comparing and displaying the past evaluation results stored in the storage unit and the evaluation results currently obtained by the evaluation unit. In the bone disease evaluation system according to any one of claims 1 to 3,
A storage unit for storing an evaluation reference value serving as a reference in the evaluation by the evaluation unit;
A bone disease evaluation system comprising: a comparison display unit for comparing and displaying an evaluation reference value stored in the storage unit and an evaluation result currently obtained by the evaluation unit.