Information processing device, radiographic system, information processing method, and program

Abstract

To provide an information processing device that can reduce burdens on a radiological technician and a subject when acquiring bone density by using a reference bone mineral material.SOLUTION: An information processing device 110 has: superposition determination means 117 for determining the presence or absence of a superposition part between a bone region of a subject 104 and a region of a reference bone mineral material 201 by using image data acquired by radioactive rays incident on the subject 104 and the reference bone mineral material 201; and bone density acquisition means 118 for acquiring bone density of the subject 104 by calibrating the image data in accordance with a determination result by the superposition determination means 117.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an information processing device, a radiation imaging system, an information processing method, and a program. [Background technology]

[0002] There is a technology called DXA (Dual Energy X-ray Absorptiometry) that performs energy subtraction from captured X-ray images to generate an image of only the bones (bone image) with soft tissue removed, and then calculates bone density from the bone image.With the aging of the global population, the number of osteoporosis patients is on the rise, and the demand for bone density measurement using DXA is increasing year by year.

[0003] Bone density measurement using the DXA method must be highly reproducible, and the approval standards for X-ray bone density measurement devices (Yakushoku Notification No. 0401050, April 1, 2005) require that the coefficient of variation for reproducibility be 1% or less.

[0004] Patent Document 1 discloses a technology that eliminates the need for daily calibration by placing a reference bone mineral material on the back of the subject on the bed and simultaneously photographing the subject during bone density imaging, while preventing a decrease in accuracy due to errors caused by differences in conditions between calibration and imaging the actual subject. Patent Document 2 discloses a technology that omits daily calibration by placing reference bone mineral material around the subject so that it is reflected in the image when the subject's bone density is being imaged, and simultaneously photographing the subject, while preventing a decrease in accuracy due to errors caused by differences in conditions between calibration and when actually imaging the subject. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-246343 [Patent Document 2] Japanese Patent Application Publication No. 8-266528 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the method of Patent Document 1 in which the reference bone mineral material is placed on the back of the subject and on the bed has the following problems. Because the subject overlaps the reference bone mineral material, it is difficult for the radiologist to grasp the positional relationship between the X-ray radiation field, the subject's imaging area (lumbar vertebrae, femur, etc.), and the reference bone mineral material. Furthermore, if the positional relationship is not appropriate after the actual X-ray is taken, re-examination will be necessary, which not only exposes the subject to unnecessary radiation but also requires the subject to move, placing a burden on both the radiologist and the subject.

[0007] Furthermore, the method of Patent Document 2 in which the reference bone mineral material is arranged so as to be reflected around the subject has the following problems. For each X-ray, reference bone mineral material must be positioned around the subject so that it is reflected in the image. However, when imaging the lumbar spine or femur, it is difficult to secure space to place the reference bone mineral material, which places a burden on the radiologist and the subject when positioning.

[0008] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an information processing device that can reduce the burden on radiologists and subjects when obtaining bone density using reference bone mineral substances. [Means for solving the problem]

[0009] The information processing device of the present disclosure includes an overlap determination means for determining whether there is an overlap area between a bone region of a subject and a region of reference bone mineral material in image data acquired by radiography, and a bone density acquisition means for calibrating the image data in accordance with the determination result by the overlap determination means and acquiring the bone density of the subject.

[0010] The information processing method disclosed herein includes a first step of determining whether there is an overlapping area between the subject's bone region and a reference bone mineral material region in image data obtained by radiography, and a second step of calibrating the image data according to the determination result of the first step and obtaining the subject's bone density. [Effects of the Invention]

[0011] According to the present disclosure, an information processing device is realized that can reduce the burden on radiologists and subjects when obtaining bone density using reference bone mineral substances. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram showing the configuration of a radiation imaging system according to an embodiment of the present invention. [Figure 2] 3 is a schematic diagram for explaining a radiation exposure field fixing mask and a reference bone mineral substance in the present embodiment. FIG. [Figure 3] 10 is a schematic diagram showing an example of an arrangement in which a plurality of reference bone mineral substances are arranged inside a radiation exposure field fixing mask in this embodiment. FIG. [Figure 4] FIG. 10 is a block diagram showing another example of the configuration of the radiation imaging system according to the present embodiment. [Figure 5] 3 is a flowchart illustrating an information processing method according to the present embodiment. [Figure 6] FIG. 2 is a schematic diagram for explaining a bone image in the present embodiment. [Figure 7] FIG. 10 is a block diagram showing another example of the configuration of the radiation imaging system according to the present embodiment. [Figure 8] FIG. 8 is a schematic diagram for explaining a method for extracting a reference bone mineral substance permeable region using the configuration of FIG. 7. [Figure 9] 6 is a flowchart showing a specific example of S507 in FIG. 5. [Figure 10] FIG. 4 is a characteristic diagram for explaining the bone density of a reference bone mineral substance permeable region in the present embodiment. [Figure 11]FIG. 4 is a characteristic diagram for explaining a calibration curve in the present embodiment. [Figure 12] FIG. 10 is a characteristic diagram for explaining a calibration curve in a modified example of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] -Basic configuration of information processing device in embodiment- Before specifically disclosing the embodiments, the basic configuration of an information processing device in the present disclosure will be described.

[0014] The information processing device according to the present disclosure is an information processing device that acquires bone density of a subject using image data in a radiography system that irradiates the subject with radiation, detects the radiation that has passed through the subject, and acquires image data of the radiation.

[0015] This information processing device has an overlap determination means and a bone density acquisition means. The overlap determination means determines whether there is an overlap between the bone region of the subject and the region of the reference bone mineral material using image data acquired by radiography. The bone density acquisition means calibrates the image data in accordance with the determination result by the overlap determination means and acquires the bone density of the subject.

[0016] In the present disclosure, in order to perform radiography of the reference bone mineral material simultaneously with the subject, the reference bone mineral material is placed between the radiation source irradiating radiation and the radiation detection device so that the reference bone mineral material is within the radiation exposure area. In this case, the subject may overlap the reference bone mineral material, which may result in insufficient calibration accuracy. Therefore, in the present disclosure, an overlap determination means determines whether or not there is an overlap between the subject's bone region and the reference bone mineral material region, and provides the determination result to the bone density acquisition means for application to calibration of the image data, thereby aiming to achieve sufficient calibration accuracy. If the information processing device has an overlap determination means, when the overlap determination means determines that there is an overlap, the bone density acquisition means can calibrate the image data using, for example, information on a region of the reference bone mineral material other than the overlap region. Specifically, the overlap determination means may select the overlap region using information on the subject's bone region extracted from the image data and information on the reference bone mineral material region extracted from the image data.

[0017] As the reference bone mineral substance, for example, one continuous reference bone mineral substance may be used, and information on the non-overlapping regions of the reference bone mineral substance may be used for calibration. Preferably, a plurality of reference bone mineral substances are arranged in the radiation irradiation region, and calibration is performed using a reference bone mineral substance determined by the overlap determination means to have no overlapping regions among the plurality of reference bone mineral substances. By arranging a plurality of reference bone mineral substances, the presence or absence of overlapping regions of each reference bone mineral substance can be clearly grasped, and only reference bone mineral substances having no overlapping regions can be easily and reliably selected.

[0018] Preferred embodiments to which the present disclosure can be applied will be described in detail below with reference to the drawings. In the following description, common components across multiple drawings are assigned common reference numerals. Therefore, the common components will be described with mutual reference to multiple drawings, and descriptions of the components assigned common reference numerals will be omitted as appropriate. The radiation in the various embodiments may include α-rays, β-rays, γ-rays, and the like, which are beams formed by particles (including photons) emitted by radioactive decay, as well as beams having the same or higher energy levels, such as X-rays, particle beams, and cosmic rays.

[0019] -Implementation- In this embodiment, an example of a radiation imaging system including an information processing device to which the present disclosure is applied will be described.

[0020] <Configuration of Radiography System> FIG. 1 is a block diagram showing the configuration of a radiation imaging system according to this embodiment. The radiation imaging system includes a radiation generator 106, a radiation source 101, a radiation exposure field aperture 102, a radiation exposure field fixing mask 103, a radiation grid 105, an FPD 107 which is a radiation detector, a monitor 111, an operation unit 112, and an information processing device 110.

[0021] In the radiation imaging system, when an exposure switch is pressed, the radiation generating device 106 applies a high voltage pulse or a low voltage pulse to the radiation source 101. This causes the radiation source 101 to irradiate the subject 104 with radiation. The radiation irradiation field aperture 102 can adjust the radiation irradiation range.

[0022] The radiation irradiation field fixing mask (irradiation field mask) 103 is made of a radiation-shielding material and can fix the irradiation range. In this case, since the irradiation range is limited by the radiation irradiation field fixing mask 103, it is preferable to set the radiation field aperture 102 to maximize the irradiation range. The radiation irradiation field fixing mask 103 can suppress exposure to areas outside the region of interest of the subject 104 and can also suppress scattered rays generated from the subject 104. Furthermore, since the radiation irradiation field fixing mask 103 has a fixed irradiation field, it also serves to improve the reproducibility of bone density measurement by suppressing scattered rays generated from the subject 104. The radiation grid 105 can prevent scattered rays generated from the subject 104 from entering the FPD 107.

[0023] The FPD (flat panel radiation detector) 107 receives radiation emitted from the radiation source 101 and transmitted through the subject 104, accumulates charges based on image signals, and then acquires a radiation image. The FPD 107 transfers the acquired radiation image to the information processing device 110. The monitor 111 receives information about the radiation image from the control unit 114 and displays the radiation image. The operation unit 112 can input instructions to the FPD 107 and the image processing unit 120.

[0024] <Configuration of information processing device> The information processing device 110 includes a control unit 114 and an image processing unit 120 . The control unit 114 controls the FPD 107 and the image processing unit 120. The control unit 114 acquires bone images of the subject 104 by processing a plurality of radiation images obtained by irradiating the subject 104 with different radiation energies.

[0025] The image processing unit 120 includes a gain correction unit 115, an image data generation unit 116, a superposition determination unit 117, and a bone density acquisition unit 118. The bone density acquisition unit 118 includes a bone region extraction unit 121, a reference bone mineral substance transmission region extraction unit 122, and a bone density calculation unit 123.

[0026] The gain correction unit 115 performs gain correction using two types of subject images with different amounts of energy. The image data generation unit 116 acquires image data from radiation incident on the subject 104 and a reference bone mineral material (not shown in FIG. 1). The bone region extraction unit 121 extracts information about the bone region of the subject 104 from the image data generated by the image data generation unit 116. The reference bone mineral material transmission region extraction unit 122 extracts information about the reference bone mineral material transmission region from the image data generated by the image data generation unit 116. The superposition determination unit 117 selects a region (non-superposition region) where the bone region and the reference bone mineral material transmission region do not overlap (non-superposition region) using information about the predetermined bone region of the subject 104 extracted by the bone region extraction unit 121 and information about the reference bone mineral material transmission region extracted by the reference bone mineral material transmission region extraction unit 122.

[0027] <Reference bone mineral substance arrangement> In this embodiment, the reference bone mineral material 201 is arranged between the radiation source 101 and the FPD 107 so that the reference bone mineral material 201 is appropriately positioned within the radiation irradiation area. When performing radiation imaging of the subject 104, for example, a radiation irradiation field fixing mask 103 shown in FIG. 2(b) is used. In this embodiment, the radiation irradiation field fixing mask 103 has the reference bone mineral material 201 arranged, for example, at each of the periphery (four corners, four sides, etc.) of the radiation irradiation area. The reference bone mineral material 201 is made of a material such as acrylic to simulate soft tissue of the human body, and has a structure simulating a bone having a known bone mineral amount (bone density) inside.

[0028] In this embodiment, as an example, a structure simulating bone mineral content in stages, in this case a reference bone mineral material 201 in which bone portions having portions with different levels of known bone mineral content (predetermined values) are arranged, is used. As shown in FIG. 2(c), the reference bone mineral material 201 has bone portions 201-1, 201-2, and 201-3 with different bone densities. The bone densities of the bone portions are as follows: bone portion 201-1 is 0.5 g / cm 2 , the bone part 201-2 is 1.0 g / cm 2 , the bone part 201-3 is 1.5g / cm 2 The reference bone mineral material 201 is arranged so that the structural surfaces of bone portions 201-1, 201-2, and 201-3, which simulate bone mineral content in stages, are approximately perpendicular to the radiation source 101 (radiation incidence direction).

[0029] FIG. 3 is a plan view showing an example of an arrangement in which a plurality of reference bone mineral materials 201 are arranged inside the radiation exposure field fixing mask 103. In FIG. Reference numeral 301 denotes the radiation exposure area adjusted by the radiation exposure field fixing mask 103, and 302 denotes the radiation exposure area of ​​the reference bone mineral material that has passed through the reference bone mineral material 201. In Fig. 3(a), the reference bone mineral material 201 is arranged at two or more locations at the four corners of the radiation exposure area 301, i.e., at four locations at each of the four corners as in Fig. 2(b). In Fig. 3(b), the reference bone mineral material 201 is arranged at two or more locations at each of the four sides of the radiation exposure area 301, i.e., at four locations at each of the four sides. In Fig. 3(c), the reference bone mineral material 201 is arranged at two or more locations at each of the four corners and two or more locations at each of the four sides of the radiation exposure area 301, i.e., at four locations at each of the four corners and two locations on each of the four sides.

[0030] In this embodiment, as described above, a plurality of reference bone mineral materials 201 are arranged on the periphery of the radiation exposure region 301 and used for radiography of the subject 104. Information on the region of the reference bone mineral material 201 through which radiation has passed is used for bone density calibration. If the subject 104 overlaps the reference bone mineral material 201 during radiography, the overlapping region of the reference bone mineral material 201 cannot be used for calibration because the calibration accuracy decreases. In this embodiment, by appropriately arranging the plurality of reference bone mineral materials 201 on the periphery of the radiation exposure region 301, it is highly likely that the subject 104 will not be overlapped with some of the plurality of reference bone mineral materials 201 in the captured image data. By arranging the reference bone mineral materials 201 as described above and performing bone density calibration using the reference bone mineral materials 201 that do not overlap with the subject 104, an accurate bone density of the subject 104 can be obtained.

[0031] In this embodiment, the reference bone mineral material 201 is disposed between the radiation source 101 and the FPD 107 so that the reference bone mineral material 201 is appropriately positioned within the radiation exposure region. As an example, the case where the reference bone mineral material 201 is disposed on the radiation exposure field fixing mask 103 has been described, but the present invention is not limited to this. The reference bone mineral material 201 may be appropriately positioned within the radiation exposure region, for example, at a predetermined position 401 inside the bed 410, a predetermined position 402 on the radiation grid 105, or a predetermined position 403 on the FPD 107 in FIG. 4. Although FIG. 4 illustrates an example where one reference bone mineral material 201 is disposed at each position, it is preferable to dispose multiple reference bone mineral material 201. Regardless of which of the predetermined positions 401 to 403 the reference bone mineral material 201 is disposed at, the reference bone mineral material 201 is disposed so as to be appropriately positioned on the periphery of the radiation exposure region 411 during radiography. Therefore, by adopting the arrangement of the reference bone mineral material 201 as shown in Figure 4, it is possible to achieve the same effect as when the reference bone mineral material 201 is arranged on the radiation irradiation field fixing mask 103 as shown in Figures 3(a) to (c).

[0032] <Information processing method> Next, information processing using the image processing unit 120 of this embodiment will be described. FIG. 5 is a flowchart showing an information processing method according to this embodiment.

[0033] [S501: Gain image capture] In order to perform gain correction to cancel differences in radiation sensitivity due to pixels of the FPD 107 and the dose and distribution of radiation emitted by the radiation source 101, gain image capture, which is a radiation image in which the subject 104 is excluded, is performed using the following procedure.

[0034] 2(a) is attached to the radiation irradiation field aperture 102, and the radiation irradiation field is aligned with the imaging region of the subject 104. With the subject 104 excluded, the radiation generator 106 applies one high-voltage pulse and one low-voltage pulse to the radiation source 101 to irradiate radiation. The FPD 107 generates a high-energy gain image in the case of high-voltage pulse exposure and a low-energy gain image in the case of low-voltage pulse exposure by irradiating radiation, and transfers these to the control unit 114.

[0035] [S502: Subject Imaging] 2(b), a radiation irradiation field fixing mask 103 equipped with a reference bone mineral material 201 is attached to a radiation irradiation field aperture 102, and the radiation irradiation field is aligned with the imaging region of a subject 104. The radiation generator 106 applies a high-voltage pulse and a low-tube voltage pulse to the radiation source 101 to expose the subject 104. By applying radiation, the FPD 107 generates a high-energy subject image in the case of high-voltage pulse exposure and a low-energy subject image in the case of low-voltage pulse exposure, and transfers these to the control unit 114.

[0036] [S503: Gain correction] The gain correction unit 115 divides the high-energy object image acquired in S502 by the high-energy object image acquired in S501 to obtain a high-energy image I H The gain correction unit 115 divides the low-energy object image acquired in S502 by the low-energy object image acquired in S501 to generate a low-energy image I L The gain correction is performed to accurately calculate bone density by canceling out differences in radiation sensitivity among the pixels of the FPD 107 and the dose and distribution of radiation irradiated by the radiation source 101.

[0037] [S504: Bone image generation] The image data generator 116 generates a high-energy image I H and low energy image I LUsing the following equation (1), the bone image d shown in Figure 6(a) is obtained as image data. B Generate.

[0038] d B (x,y)=lnI L (x,y)-αlnI H (x,y) (1) In equation (1), x represents the pixel position in the horizontal direction of the image, y represents the pixel position in the horizontal direction of the image, and α represents a coefficient determined for soft tissue removal.

[0039] High Energy Imaging I H or low energy image I L In this case, the area consisting of only soft tissue and no bone is shown in the bone image d in Fig. 6(a). B Therefore, the high-energy image I H and low energy image I L The coefficient α in equation (1) can be calculated from the region consisting of only soft tissue.

[0040] [S505: Extraction of bone regions] The bone region extraction unit 121 of the bone density acquisition unit 118 extracts the bone image d in FIG. B For example, the bone image d B By performing segmentation processing using binarization, region expansion, edge detection, and graph cut on the bones, information on the spine, pelvis, and femur regions is extracted as shown in FIG. 6(b). Here, if radiographic images of many subjects are available, the bone region extraction unit 121 may extract information on the bone regions of the subject 104 using segmentation by machine learning. In addition, when the user selects a bone image d B It is also possible to extract information about the bone regions of the subject 104 by more manually selecting a Region of Interest (ROI) for the bone region.

[0041] [S506: Extraction of reference bone mineral permeability region] The reference bone mineral material transmission region extraction unit 122 of the bone density acquisition unit 118 extracts the bone image d in FIG. B For example, the information of the reference bone mineral penetration area is extracted from the bone image d. B By performing segmentation processing using binarization, region growing, edge detection, and graph cut on the reference bone mineral material 201, information on the reference bone mineral material transmission regions 601 to 604 where radiation has penetrated and been exposed to the reference bone mineral material 201 is extracted as shown in FIG. 6(c). B A more manual method of selecting ROIs for bone regions also allows for the extraction of reference bone mineral penetration region information.

[0042] The reference bone mineral substance permeable region may be extracted, for example, by the following method. Fig. 7 is a schematic diagram showing a radiography system having another aspect of extracting a reference bone mineral substance permeable region in this embodiment, Fig. 8 is a plan view showing a radiation irradiation field appearing on a subject.

[0043] For example, as shown in FIG. 7, an optical camera 701 is attached to the radiation source 101. For example, as shown in FIG. 8, a light region 801 that indicates the radiation irradiation field appearing on the subject 104 is observed by the optical camera 701. Within the light region 801, a shadow 802 appears as a result of the light passing through the reference bone mineral material 201. Information about the position of the shadow within the light region 801 is transferred from the optical camera 701 to the information processing device 110. Using this shadow position information, the bone image d in FIG. 6(a) is generated. B This makes it possible to extract information on the reference bone mineral penetration region.

[0044] [S507: Selection of reference bone mineral permeability region] The overlap determination unit 117 determines whether the bone image d in FIG. B is used to select a region (non-overlapping region) where the bone region of the subject 104 and the reference bone mineral substance permeation region do not overlap. If the region where the reference bone mineral substance permeation region overlaps with the bone region is used for bone density calibration, this will cause a decrease in measurement accuracy. By selecting a reference bone mineral substance permeation region that does not overlap with the bone region, highly accurate bone density calibration can be reliably performed.

[0045] A specific example of S507 is shown in Fig. 9. For convenience of illustration, Fig. 9 also shows S501 to S506 and S508 in the same way as Fig. 5. For example, the bone regions extracted in Fig. 6(b) are the lumbar vertebrae and femur. In bone density measurement, measurements are mainly performed on the lumbar vertebrae or femur, which are clinically important.

[0046] In S901, the overlap determination unit 117 determines whether or not there is an overlap between the lumbar vertebrae or femur in the bone region and the reference bone mineral material transmission region, using, for example, the bone region extracted in Fig. 6(b) and the reference bone mineral material transmission region extracted in Fig. 6(c). This determination is automatically performed by the overlap determination unit 117 using, for example, segmentation processing or manual ROI selection, information on the bone region extracted in S505 and information on the reference bone mineral material transmission region extracted in S506. If there is an overlap between the two, the process proceeds to S902. If there is no overlap, the process proceeds to S903.

[0047] In S902, the superposition determination unit 117 determines whether or not the entire reference bone mineral substance transmission region is superimposed on the bone region. Because S902 is a series of steps executed following S901, this determination is automatically performed by the superposition determination unit 117 using the information on the bone region extracted in S505 and the information on the reference bone mineral substance transmission region extracted in S506, as in S901. If there is a non-overlapping portion in the reference bone mineral substance transmission region that does not overlap with the bone region, the process proceeds to S903. If the entire reference bone mineral substance transmission region is superimposed on the bone region, the process proceeds to S904.

[0048] In S903, the overlap determination unit 117 selects a reference bone mineral substance permeable region in a non-overlapping portion that does not overlap with the bone region as a reference bone mineral substance permeable region to be used for calibration. In S904, the overlap determination unit 117 displays a warning on the monitor 111 to the effect that the reference bone mineral substance transmission regions are all overlapped with the bone regions and that bone density cannot be obtained, to alert the user (radiologist, etc.). Then, the process returns to S502. The user, noticing the warning, readjusts the body position of the subject 104 so that the reference bone mineral substance transmission regions do not overlap with the bone regions, and the subject image is captured again in S502.

[0049] In this embodiment, in S507, since the reference bone mineral substance transmission regions 603 and 604 overlap with bone regions such as the pelvis and femur, the overlap determination unit 117 selects the reference bone mineral substance transmission regions 601 and 602 that do not overlap with the bone regions as the regions to be used for calibration. Instead of using the overlap determination unit 117, it is also possible to use a software GUI (Graphical User Interface) and a mouse or the like as means for overlap determination, and to perform manual selection from the GUI using the mouse or the like.

[0050] [S508: Bone Density Calibration] The bone density calculation unit 123 of the bone density acquisition unit 118 calculates the bone image d shown by equation (1) in FIG. 6(a) acquired in S504 using the transmission region of the reference bone mineral substance without the overlapping region selected in S507. B The bone mineral density of the reference bone mineral material 201 is known (201-1: 0.5 g / cm 2 , 201-2:1.0g / cm 2 , 201-3:1.5g / cm 2 ), and the pixel values ​​for the areas that pass through the bone portions 201-1, 201-2, and 201-3 are as shown in Fig. 10. In Fig. 10, the pixel values ​​corresponding to the bone portions 201-1, 201-2, and 201-3 are represented as 10a, 10b, and 10c.

[0051] FIG. 11 is a characteristic diagram showing the relationship between the pixel value of the reference bone mineral material 201 and the bone density. A calibration curve 1101 is obtained from the relationship between the pixel values ​​of the bone portions 201-1, 201-2, and 201-3 of the reference bone mineral material 201 and the corresponding bone densities. Using this calibration curve 1101, the bone image d shown in equation (1) of FIG. 6(a) is calculated from the following equation (2): B The whole bone density image B can be calibrated to '.

[0052] d B '(x,y)=K1[lnI L (x,y)-αlnI H (x,y)]+K2 (2) Here, K1 represents the slope of the calibration curve 901, and K2 represents the intercept of the calibration curve 901. B ' is the surface density in g / cm 2 From equation (2), the bone density image d B The distribution of bone density of the subject can be obtained.

[0053] As described above, according to this embodiment, by radiographing the reference bone mineral material 201 simultaneously with the subject 104, the imaging conditions and the like are equivalent for the subject 104 and the reference bone mineral material 201, thereby improving the reproducibility and accuracy of bone mineral density measurements. When obtaining bone density using the reference bone mineral material, the presence or absence of an overlapping area between the bone region and the reference bone mineral material transmission area is determined, and calibration is performed using the reference bone mineral material transmission area without an overlapping area. This reduces the burden on the radiologist and the subject, and enables the subject's bone density to be determined efficiently and accurately.

[0054] -Variations- A modified example of the information processing device according to this embodiment will be described below. In this modified example, a method that can be suitably applied particularly when a plurality of reference bone mineral substances are arranged between the radiation source and the radiation detection device will be disclosed.

[0055] FIG. 12 is a characteristic diagram showing the relationship between the pixel value of the reference bone mineral material 201 and the bone density in this modified example. For example, consider a case where multiple reference bone mineral substance transmission regions 201 are arranged on the periphery of the radiation exposure region as in Fig. 2(b) and a bone image similar to that shown in Fig. 6(a) is acquired. In this case, the overlap determination unit 117 selects reference bone mineral substance transmission regions 601 and 602 as regions of the reference bone mineral substance transmission region that do not overlap with the bone region as in Fig. 2(c). When two or more reference bone mineral substance transmission regions are selected as non-overlapping regions that do not overlap with the bone region, multiple calibration curves can be obtained using information on each of the reference bone mineral substance transmission regions.

[0056] The multiple calibration curves may differ from one another due to the influence of scattered radiation, as in the case of calibration curves 1201 and 1202. Calibration curve 1201 shows the relationship between pixel values ​​10a, 10b, and 10c of bone portions 201-1, 201-2, and 201-3 of reference bone mineral material 201 in reference bone mineral substance transmission region 601 and the corresponding bone densities. Calibration curve 1202 shows the relationship between pixel values ​​10a', 10b', and 10c' of bone portions 201-1, 201-2, and 201-3 of reference bone mineral material 201 in reference bone mineral substance transmission region 602 and the corresponding bone densities.

[0057] In this modification, a new calibration curve is created by averaging the obtained multiple different calibration curves. Specifically, pixel values ​​10a and 10a', pixel values ​​10b and 10b', and pixel values ​​10c and 10c' are averaged in calibration curve 1201 and calibration curve 1202, respectively. A calibration curve 1203 is created from the relationship between the averaged pixel values ​​of bone portions 201-1, 201-2, and 201-3 of the reference bone mineral material 201 and the corresponding bone densities. From the above equation (2), the bone image d B The whole bone density image B In this way, the bone density of the subject can be obtained with higher accuracy.

[0058] -Other embodiments- In the above-described embodiment and modified examples, a computer program for controlling the information processing device 110 is stored in a storage medium such as a ROM, HDD, or SSD. This computer program is a program for implementing the functions of the components of the information processing unit 120 of the information processing device 110, such as the gain correction unit 115, image data generation unit 116, superposition determination unit 117, and bone density acquisition unit 118, for example, corresponding to steps S501 to S508 in FIG. 5 and steps S901 to S904 in FIG. 9. The control unit 114 is, for example, the CPU 10, and reads and executes the computer program from the ROM or storage medium. In this way, the control unit 114 performs overall control of the information processing unit 120 and the like.

[0059] The disclosure of the various embodiments includes the following configurations and methods. (Configuration 1) an overlap determination means for determining whether an overlapping portion exists between the bone region of the subject and the region of the reference bone mineral material in image data acquired by radiography; a bone density acquisition unit that calibrates the image data in accordance with the determination result of the superposition determination unit and acquires the bone density of the subject; having Information processing device. (Configuration 2) When the overlap determination means determines that the overlapping portion exists, The bone density acquisition means calibrating the image data using information on a region of the reference bone mineral material other than the overlapping region; 2. The information processing device according to configuration 1. (Configuration 3) The overlap determination means Information on the bone region of the subject extracted from the image data; and information on the reference bone mineral material region extracted from the image data; determining the overlapping portion to be used for calibrating the image data using 3. The information processing device according to configuration 1 or 2. (Configuration 4) The bone density acquisition means calibrating the image data using the reference bone mineral materials determined by the overlap determination means not to have the overlap portion among the plurality of reference bone mineral materials; 4. The information processing device according to configuration 2 or 3. (Configuration 5) The reference bone mineral material is disposed in a region between a radiation source that emits radiation and a radiation detection device; 5. The information processing device according to any one of configurations 1 to 4. (Configuration 6) The reference bone mineral material is disposed on at least one of the radiation source, the bed, the radiation grid, and the radiation detection device; 6. The information processing device according to configuration 5. (Configuration 7) The reference bone mineral material is a radiation field mask for limiting the radiation field of the radiation source; 6. The information processing device according to configuration 5. (Configuration 8) The reference bone mineral material is The bone mineral density has a plurality of portions set to predetermined values ​​that vary in stages. 8. The information processing device according to any one of configurations 1 to 7. (Configuration 9) The plurality of reference bone mineral materials comprises: disposed on the periphery of the radiation exposure area; 9. The information processing device according to any one of configurations 1 to 8. (Configuration 10) The plurality of reference bone mineral materials comprises: The radiation irradiated area is arranged so as to be located at two or more of the four corners, two or more of the four sides, or two or more of the four corners and the four sides. 10. The information processing device according to configuration 9. (Configuration 11) further comprising an optical camera for capturing an image of a light region of the radiation field; The bone density acquisition means extracting information about the region of the reference bone mineral material from the image data using position information of a shadow that appears when radiation passes through the reference bone mineral material in the optical region photographed by the optical camera; 3. The information processing device according to configuration 1 or 2. (Configuration 12) a plurality of said reference bone mineral materials are disposed; When the overlap determination means determines that the overlapping portion does not exist in two or more of the reference bone mineral substances among the plurality of reference bone mineral substances, the bone mineral density acquisition means acquires two or more calibration curves respectively corresponding to the two or more reference bone mineral substances, creates a calibration curve by averaging the two or more calibration curves, and calibrates the image data using the averaged calibration curve; 12. The information processing device according to any one of configurations 1 to 11. (Configuration 13) a radiation generating device that irradiates a subject with radiation; a reference bone mineral material disposed within the radiation exposure area; An information processing device according to any one of configurations 1 to 12; a radiation detector for acquiring a radiological image by receiving radiation that has passed through the subject; having Radiography system. (Method 1) a first step of determining whether or not there is an overlapping portion between the bone region of the subject and the region of the reference bone mineral material in image data acquired by radiography; a second step of calibrating the image data according to the determination result of the first step and acquiring the bone density of the subject; having Information processing methods. (Configuration 14) A program for causing a computer to execute each step of method 1. [Explanation of symbols]

[0060] 101 Radiation source 102 Radiation field aperture 103 Radiation Field Fixed Mask 105 Radiation Grid 106 Radiation Generator 107 FPD 114 Control Unit 115 Gain correction section 116 Image data generation unit 117 Overlap determination unit 118 Bone Density Acquisition Department 110 Information processing equipment 120 Image processing unit 121 Bone region extraction part 122 Reference bone mineral material permeation area extraction part 123 Bone density calculation section 201 Reference bone mineral material 201-1,201-2,201-3 Bone part

Claims

1. an overlap determination means for determining whether an overlapping portion exists between the bone region of the subject and the region of the reference bone mineral material in image data acquired by radiography; a bone density acquisition unit that calibrates the image data in accordance with the determination result of the superposition determination unit and acquires the bone density of the subject; having Information processing device.

2. When the overlap determination means determines that the overlapping portion exists, The bone density acquisition means calibrating the image data using information on a region of the reference bone mineral material other than the overlapping region; The information processing device according to claim 1 .

3. The overlap determination means Information on the bone region of the subject extracted from the image data; and information on the reference bone mineral material region extracted from the image data; determining the overlapping portion to be used for calibrating the image data using The information processing device according to claim 1 .

4. The bone density acquisition means calibrating the image data using the reference bone mineral materials determined by the overlap determination means not to have the overlap portion among the plurality of reference bone mineral materials; The information processing device according to claim 2 .

5. The reference bone mineral material is disposed in a region between a radiation source that emits radiation and a radiation detection device; The information processing device according to claim 1 .

6. The reference bone mineral material is disposed on at least one of the radiation source, the bed, the radiation grid, and the radiation detection device; The information processing device according to claim 5 .

7. The reference bone mineral material is a radiation field mask for limiting the radiation field of the radiation source; The information processing device according to claim 5 .

8. The reference bone mineral material is The bone mineral density has a plurality of portions set to predetermined values ​​that vary in stages. The information processing device according to claim 1 .

9. The plurality of reference bone mineral materials comprises: disposed on the periphery of the radiation exposure area; The information processing device according to claim 1 .

10. The plurality of reference bone mineral materials comprises: The radiation irradiated area is arranged so as to be located at two or more of the four corners, two or more of the four sides, or two or more of the four corners and the four sides. The information processing device according to claim 9 .

11. further comprising an optical camera for capturing an image of a light region of the radiation field; The bone density acquisition means extracting information about the region of the reference bone mineral material from the image data using position information of a shadow that appears when radiation passes through the reference bone mineral material in the optical region photographed by the optical camera; The information processing device according to claim 1 .

12. a plurality of said reference bone mineral materials are disposed; When the overlap determination means determines that the overlapping portion does not exist in two or more of the reference bone mineral substances among the plurality of reference bone mineral substances, the bone mineral density acquisition means acquires two or more calibration curves respectively corresponding to the two or more reference bone mineral substances, creates a calibration curve by averaging the two or more calibration curves, and calibrates the image data using the averaged calibration curve; The information processing device according to claim 1 .

13. a radiation generating device that irradiates a subject with radiation; a reference bone mineral material disposed within the radiation exposure area; An information processing device according to any one of claims 1 to 12; a radiation detector for acquiring a radiological image by receiving radiation that has passed through the subject; having Radiography system.

14. a first step of determining whether or not there is an overlapping portion between the bone region of the subject and the region of the reference bone mineral material in image data acquired by radiography; a second step of calibrating the image data in accordance with the determination result of the first step and acquiring the bone mineral density of the subject; having Information processing methods.

15. A program for causing a computer to execute the steps recited in claim 14.

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