JP2017093911A - X-ray measurement apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve the accuracy in the measurement of the mass of a subject by an X-ray measurement apparatus.SOLUTION: A fan beam-shaped X ray is projected to a plurality of detection elements 32a from an X-ray irradiator 30. A surface density of each subject part 22a is calculated based on each detection data set (attenuation of the X ray) detected by each detection element 32a. A body thickness of each subject part 22a is also calculated based on each detection data set. A virtual measuring surface is defined at a center location of each subject part 22a in a body thickness direction based on the calculated body thickness. The surface density of each subject part 22a is multiplied by the area of each virtual measuring surface defined in each subject part 22a to calculate a plurality of element unit masses indicating the masses of respective subject parts 22a. The mass of the subject 22 is calculated by summing the plurality of element unit masses.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an X-ray measurement apparatus, and more particularly to a technique for calculating the mass of a subject.

  Conventionally, X-ray measuring apparatuses are used in medical institutions and the like. In the X-ray measurement apparatus, X-rays are irradiated toward the subject, and various measurements are performed based on the attenuation amount of the X-rays that have passed through the subject. Conventionally, an X-ray measurement apparatus generally measures a bone mineral content or a body fat percentage, but recently, a technique for measuring the mass of a subject in an X-ray measurement apparatus has been proposed. For example, Patent Document 1 discloses a technique for obtaining the weight of a subject using an X-ray measurement apparatus.

Special table 2013-532823 gazette

  One method for measuring the mass of the subject in the X-ray measurement apparatus is as follows. FIG. 5 is a diagram for explaining a conventional mass measurement method in the X-ray measurement apparatus. As shown in FIG. 5, the subject 5 is disposed between the X-ray light source 1 and the plurality of detection elements 3. X-rays emitted from the X-ray light source 1 are fan beams and are emitted from the X-ray light source 1 so as to spread in the x-axis direction. An irradiation range of X-rays irradiated from the X-ray light source 1 is indicated by a one-dot chain line.

  The plurality of detection elements 3 are arranged in the fan beam spreading direction. The X-ray transmission region detected by each detection element 3 is shown separated by a two-dot chain line. Each transmission region includes a subject portion 5 a that is a part of the subject 5. For example, the transmission region corresponding to the detection element 3a includes a subject portion 5a indicated by hatching. Since the detection element 3a (and the X-ray light source 1) is scanned in the y-axis direction, the subject portion 5a corresponding to the detection element 3a changes every moment.

  When the X-ray light source 1 and the plurality of detection elements 3 are scanned in the y-axis direction, fan beam-shaped X-rays are scanned in the y-axis direction. As a result, detection data including a plurality of detection data arranged two-dimensionally A group is obtained. FIG. 6 shows a conceptual diagram of the obtained two-dimensional detection data group 9.

  Based on the detection data detected by each detection element 3, the surface density (mass per unit area) of each subject portion 5a is obtained. Specifically, in each detection data 9a of the detection data group 9, the surface density of the corresponding subject portion 5a is obtained.

  The element unit mass for each detection data 9a is calculated by multiplying the surface density of each subject portion 5a calculated from each detection data 9a by the unit area related to the subject portion 5a corresponding to each detection data 9a. Is done. The element unit mass is the mass of each subject portion 5a. The unit area relating to each subject portion 5a is defined as the area of a surface (hereinafter referred to as “virtual measurement surface”) defined in each subject portion 5a and provided in parallel with the detection element surface 3b. That is, it can be said that the unit area relating to each subject portion 5a represents the area of a horizontal cross section (cross section in a plane parallel to the detection element surface 3b) of each subject portion 5a.

A virtual measurement surface 7 (see FIG. 5) is defined for each subject portion 5a. The distance between the X-ray light source 1 and the virtual measurement surface 7 is l ₁ , the distance between the X-ray light source 1 and the detection element surface 3b is l ₂ , and the fan beam spreading direction (x-axis direction) of each detection element 3 ) Is d _x , the length of the virtual measurement surface 7 in the x-axis direction (Δx in FIG. 5) can be obtained by the following equation.

The length of the virtual measurement surface 7 in the y-axis direction is the distance that the X-ray light source 1 and the plurality of detection elements 3 have moved in the y-axis direction until detection data is obtained in all the detection elements 3. Is Δy. If it does so, the area of the virtual measurement surface 7 will be obtained by the following formula | equation.
The area of each virtual measurement surface 7 obtained in this way is the unit area for each subject portion 5a.

  The mass (element unit mass) of each subject portion 5a is obtained by multiplying the surface density and unit area of each subject portion 5a calculated as described above, and adding a plurality of element unit masses. The mass of the subject 5 is obtained.

  As described above, the unit area regarding each subject portion 5a, that is, the area of the virtual measurement surface 7 is an important parameter that directly affects the calculated mass of the subject 5. However, conventionally, the area of the virtual measurement surface 7 has been set uniformly in each subject portion 5a. That is, the position of the virtual measurement surface 7 in each subject portion 5 a is defined as a uniform distance from the X-ray light source 1.

  When the X-ray beam shape is divergent like the fan beam shape, defining the position of the virtual measurement surface 7 uniformly may cause an error in the calculation result. As is clear from FIG. 5, when an X-ray beam having a divergent shape is used, the horizontal cross-sectional area of each subject portion 5 a is smaller as it is closer to the X-ray light source 1 and is larger as it is farther from the X-ray light source 1.

  Therefore, it is inherently necessary to appropriately define the position of the virtual measurement surface in the body thickness direction. Specifically, in the portion where the body thickness is large, the virtual measurement surface 7 should be set at a position further away from the X-ray light source 1 (that is, the area of the virtual measurement surface 7 is larger), and the portion where the body thickness is small The virtual measurement surface 7 should be set closer to the X-ray light source 1 (that is, the area of the virtual measurement surface 7 is made smaller). In other words, if the area of each virtual measurement surface 7 is uniform, that is, if the position of the virtual measurement surface 7 is defined as a uniform position from the X-ray irradiator, the mass of the portion with a thin body thickness is reduced. There is a problem that overestimation (large calculation) is performed, and that the mass is underestimated (small calculation) in a thick body portion.

  An object of the present invention is to further improve the measurement accuracy of the mass of a subject in an X-ray measurement apparatus.

  An X-ray measurement apparatus according to the present invention detects an X-ray irradiator that irradiates a subject with X-rays having a divergent beam shape, detects the X-ray that has passed through the subject, and outputs detection data. Depending on the X-ray detection element, the surface density of the subject part included in the X-ray transmission region detected by the X-ray detection element, which is specified from the detection data output by the X-ray detection element, and the detection data And a mass computation unit that computes the element unit mass by multiplying the unit area computed in this way and computes the mass of the subject based on the element unit mass.

  Preferably, a plurality of the X-ray detection elements are provided, the plurality of X-ray detection elements output a plurality of the detection data, and the mass calculation unit calculates the element unit mass for each X-ray detection element. The mass of the subject is calculated as the sum of the plurality of element unit masses calculated for the plurality of X-ray detection elements. Preferably, the unit area is calculated based on the body thickness of the subject portion calculated based on the detection data output from the X-ray detection element.

  According to the above configuration, the unit area relating to each subject portion is determined based on the detection data corresponding to each subject portion. For example, if the linear absorption coefficient of the subject is known, the body thickness of the subject portion can be calculated based on the amount of X-ray attenuation that is detection data. Based on the body thickness of each subject part calculated as described above, a unit area for each subject part can be set. As a result, it is possible to solve the conventional problem that the mass is overestimated for the thin part and the mass is underestimated for the thick part.

  Preferably, the unit area is defined as a center position in the body thickness direction of the subject portion, and is calculated as an area of a virtual measurement surface that is a surface parallel to the detection surface of the X-ray detection element.

  Since the X-rays emitted from the X-ray irradiator have a divergent beam shape, that is, a shape that spreads in the traveling direction, the area of the virtual measurement surface defined in the subject portion is the X-ray irradiator. The closer it is, the smaller it becomes, and the farther it is from the X-ray irradiator, the larger it becomes. That is, the area varies depending on the definition position of the virtual measurement surface. Here, the surface density calculated in each X-ray detection element is calculated based on X-rays transmitted through the entire object portion corresponding to each X-ray detection element. Therefore, the unit area is preferably an average area of the area of the virtual measurement surface that can be defined in the subject portion. The area of the virtual measurement surface defined at the center position in the body thickness direction of the subject portion is the average area. By setting the virtual measurement surface at the center position of the subject portion in the body thickness direction, the mass of the subject is calculated with higher accuracy.

  Preferably, the apparatus further includes warning means for outputting a warning when the body thickness of the subject portion calculated based on the detection data output from the X-ray detection element is equal to or greater than a predetermined value. X-ray measurement cannot be suitably performed on a subject whose body thickness is too thick. Therefore, when the body thickness of the subject part is equal to or greater than a predetermined value (the predetermined value is determined based on the body thickness that allows X-ray measurement to be suitably performed), a warning is output to the measurer. On the other hand, it can be suggested that the data obtained may not be appropriate.

  In addition, the X-ray measurement program according to the present invention specifies the X-ray detection specified by detection data output from an X-ray detection element that detects a X-ray having a divergent beam shape and transmitted through a subject. The element unit mass is calculated by multiplying the surface density of the subject part included in the X-ray transmission region detected by the element and the unit area calculated according to the detection data, and based on the element unit mass, the element unit mass is calculated. It is made to function as a mass calculation means for calculating the mass of the subject.

  According to the present invention, the measurement accuracy of the mass of the subject can be further improved in the X-ray measurement apparatus.

It is an external appearance perspective view of an X-ray irradiation detector. It is a figure which shows a mode that the imaging stand and the test object were set to the X-ray irradiation detector. It is a functional block diagram of the X-ray measuring apparatus which concerns on this embodiment. It is a figure for demonstrating the mass calculation method in this embodiment. It is a figure for demonstrating the conventional mass calculation method. It is a conceptual diagram which shows several detection data arranged in two dimensions.

  The X-ray measuring apparatus according to the present invention will be described below. The X-ray measurement apparatus according to the present invention is used for medical purposes and the like, based on detection data obtained by irradiating a subject with X-rays and detecting X-rays transmitted through the subject. The mass of the subject is measured. Note that the X-ray measurement apparatus can measure the bone mineral content, bone density, body fat percentage, and the like of the subject based on the detection data in addition to the mass of the subject.

  FIG. 1 is an external perspective view of an X-ray irradiation detector 10 included in an X-ray measurement apparatus according to the present invention, and FIG. 2 shows a state in which an imaging table and a subject are set on the X-ray irradiation detector 10. FIG. 1 and 2, the short direction (left and right direction) of the X-ray irradiation detector 10 is the x axis, the long direction (depth or front and back direction) is the y axis, and the height direction is the z axis.

  The X-ray irradiation detector 10 is substantially U-shaped when viewed from the side, and includes a base 12 that extends in the horizontal direction, an arm 14 that also extends in the horizontal direction above the base 12, and an upper side from one end of the base 12. And a wall portion 16 that cantilever-supports the arm portion 14.

  As shown in FIG. 2, the X-ray irradiation detector 10 is used together with an imaging table (Bucky table) 18. The X-ray irradiation detector 10 is a movable type that can be freely moved by a caster. When the X-ray irradiation detector 10 is used, the imaging table top plate 20 of the imaging table 18 includes the base 12, the arm unit 14, and the like. The position of the X-ray irradiation detector 10 is adjusted so as to be positioned between. Then, the subject 22 is placed on the imaging table top plate 20, whereby the subject 22 is disposed between the base portion 12 and the arm portion 14.

  An X-ray irradiation detector top plate 24 made of a material capable of transmitting X-rays is disposed on the upper surface of the base 12 (see FIG. 1). In the space below the X-ray irradiation detector top plate 24, an X-ray irradiator that irradiates X-rays is scanned in the depth direction (y-axis direction). X-rays are irradiated upward from the X-ray irradiator during scanning. X-rays emitted from the X-ray irradiator and passed through the subject are detected by an X-ray detector provided in the arm unit 14 and scanned in synchronization with the X-ray irradiator.

  An accommodation box 26 is attached to the front surface of the wall portion 16, and a calibration substance for mainly measuring bone density is accommodated in the accommodation box 26.

  FIG. 3 is a functional block diagram of the X-ray measuring apparatus according to the present invention. The X-ray measurement apparatus according to the present embodiment includes an X-ray irradiation detector 10 and a measurement terminal 40.

  The X-ray irradiator 30 irradiates the subject with X-rays having a divergent shape (expanding in the traveling direction). In the present embodiment, the X-ray irradiation detector 10 emits fan beam-shaped X-rays that spread in the left-right direction (x-axis direction). The X-ray irradiation detector 10 according to the present embodiment can irradiate a subject with high-energy X-rays and low-energy X-rays. As a result, in the measurement terminal 40 described later, based on the ratio of the attenuation amount of both X-rays, that is, the DEXA (Dual-Energy X-ray Absorptiometry) method, the body fat percentage or the bone mineral content can be calculated.

  The X-ray detector 32 detects X-rays emitted from the X-ray irradiator 30 and passed through the subject 22. The X-ray detector 32 includes a plurality of detection elements arranged in a direction corresponding to the shape of the X-ray irradiated from the X-ray irradiator 30. In the present embodiment, the X-ray irradiator 30 emits X-rays having a fan beam shape extending in the left-right direction. Therefore, the X-ray detector 32 includes a plurality of detection elements arranged in a line in the left-right direction. Including. Alternatively, an X-ray detector in which a plurality of detection elements are aligned in the two-dimensional direction of the left-right direction and the depth direction may be used.

  The scanning unit 34 scans the X-ray irradiator 30 and the X-ray detector 32 in the depth direction. As a result, fan-beam X-rays are scanned in the depth direction. Each detection element included in the X-ray detector 32 detects X-rays while scanning itself, and each detection data obtained by the detected X-rays is sent to the measurement terminal 40 via the control unit 36 described later. Send. As a result, the measurement terminal 40 obtains a detection data group (see FIG. 6) including a plurality of detection data arranged two-dimensionally.

  The control unit 36 is composed of, for example, a microprocessor and controls each unit of the X-ray irradiation detector 10 according to a program stored in a storage unit (not shown) provided in the X-ray irradiation detector 10. The control unit 36 transmits an X-ray irradiation start and irradiation stop instruction to the X-ray irradiator 30 to cause the X-ray irradiator 30 to start and stop X-ray irradiation, or to the scanning unit 34. The scanning instruction is transmitted to cause the scanning unit 34 to scan the X-ray irradiator 30 and the X-ray detector 32.

  The measurement terminal 40 is a terminal used by a measurer such as a doctor or a nurse, and is a personal computer, for example. The measurement terminal 40 and the X-ray irradiation detector 10 are communicably connected to each other by wire or wirelessly, and are arranged in a separate room from the X-ray irradiation detector 10 in order to prevent exposure of the measurer. The measurement terminal 40 includes a calculation unit 42 and a storage unit 44.

  The computing unit 42 is realized by a computing device such as a CPU, for example. The calculation unit 42 calculates the mass of the subject 22 based on the detection data group transmitted from the X-ray irradiation detector 10 (control unit 36). In the present embodiment, the calculator 42 particularly calculates the mass of the subject of the soft tissue that does not include the bone. The calculation unit 42 also has a function of designating a region (ROI) of a subject whose mass is to be calculated. The designation of the ROI may be performed in accordance with an instruction from a measurer (that is, manually) input from an input unit (not shown) included in the measurement terminal 40, or may be performed on detection data from the X-ray irradiation detector 10. It may be set automatically based on this. Note that the calculation unit 42 can calculate the bone mineral content, bone density, body fat percentage, and the like of the subject by the DEXA method based on the detection data group regarding the high energy X-rays and the low energy X-rays. Details of the mass calculation processing in the calculation unit 42 will be described later.

  The storage unit 44 includes a hard disk, a ROM, a RAM, and the like, and stores a detection data group transmitted from the X-ray irradiation detector 10, a program for operating each unit of the measurement terminal 40, and the like.

  In addition, the measurement terminal 40 includes an image forming unit that forms an image such as an X-ray image, a display unit including a liquid crystal panel, a CPU, and the like. The measurement terminal 40 is based on a program stored in the storage unit 44. And a control unit that controls each of the above and a mouse or a keyboard, etc., and an input unit for inputting a measurement person's instruction to the measurement terminal 40.

  Hereinafter, a calculation process for calculating the mass of the subject in the calculation unit 42 will be described.

  FIG. 4 is a conceptual side view when the X-ray irradiation detector 10 is viewed from the front side direction, and shows the positional relationship with the X-ray irradiation device 30, the X-ray detector 32, and the subject 22. .

  As described above, the X-ray detector 32 has a plurality of detection elements 32a arranged in the left-right direction (x-axis direction). The plurality of detection elements 32a are rectangular or square in plan view, and the lengths in the left-right direction are uniform.

  A fan beam-shaped X-ray that spreads in the left-right direction is irradiated upward from a point light source 30 a included in the X-ray irradiator 30. In FIG. 4, the irradiation range of the irradiated X-rays is indicated by a one-dot chain line. Within the irradiation range, a subject 22 placed on the imaging table top 20 or a part to be measured (hereinafter collectively referred to as “subject”) is arranged. For convenience, in FIG. 4, the cross section of the subject 22 is shown as a semicircle.

  As shown in FIG. 4, the X-rays emitted from the point light source 30a are transmitted through the subject 22 and detected by the plurality of detection elements 32a. In FIG. 4, X-ray transmission regions detected by the detection elements 32 a are shown separated by two-dot chain lines. A part of the subject 22 included in each transmission region is a subject portion 22a. Each detection element 32a detects X-rays transmitted through the corresponding subject portion 22a and attenuated, and outputs a plurality of detection data corresponding to each subject portion 22a based on the detected X-ray.

  Also in the present embodiment, as in the prior art, the mass (element unit mass) of each subject portion 22a is calculated by multiplying the surface density for each subject portion 22a by the unit area corresponding to each subject portion 22a. The mass of the subject 22 is calculated by adding each element unit mass corresponding to a plurality of detection data. However, in the present embodiment, the unit area setting method is different from the conventional one. Details will be described below.

First, a method for calculating the surface density for each subject portion 22a will be described. It is known that the attenuation amount of X-rays transmitted through a soft tissue in which no bone part is present is expressed by the following equation.
In Equation 3, _RH is the attenuation when high-energy X-rays pass through the subject, μ _HS is the linear absorption coefficient (unit: “1 / cm”) of soft tissue, and X _s is the subject. The thickness of the specimen 22 (unit: “cm”). The mass calculation is performed using high energy X-rays from the viewpoint of simplifying the calculation process. Specifically, it is known that the linear absorption coefficient μ _HS for high-energy X-rays is substantially the same between the fat and the lean portion. Therefore, by using high-energy X-rays, μ _HS can be defined as the linear absorption coefficient of the entire soft tissue where fat and lean are mixed, thereby simplifying the calculation.

Here, since the linear absorption coefficient μ _HS is obtained by multiplying the density of the subject 22 by the mass absorption coefficient, it is expressed by the following equation.
In Equation 4, ρ is the density of the subject 22 (unit is “g / cm ³ ”), and μ ′ _HS is the mass absorption coefficient (unit is “cm ² / g”). It is known that the mass absorption coefficient μ ′ _HS is substantially the same in the fat portion and the lean portion.

Further, the thickness X _s of the subject is obtained by dividing the surface density (mass per unit area) of the subject 22 by the density of the subject 22, and is expressed by the following equation.
In Equation 5, σ is the surface density σs (unit: “g / cm ² ”).

Substituting Equation 4 and Equation 5 into Equation 3 yields the following equation:
Equation 6 means that the attenuation amount (R _H ) of high energy X-rays is proportional to the surface density σ. Since the mass absorption coefficient μ ′ _HS is a known value, according to Equation 6, the surface density σ of the subject 22 is based on the attenuation amount of the X-ray when the subject 22 is irradiated with high-energy X-rays. Can be calculated. Through the above calculation, a plurality of surface densities σ corresponding to each subject portion 22a are calculated based on each detection data (attenuation amount of high energy X-rays) arranged two-dimensionally.

  Next, a method for setting a unit area for each subject portion 22a will be described. In the present embodiment, the unit area for each subject portion 22a is calculated according to the detection data corresponding to each subject portion 22a. Specifically, the body thickness of each subject portion 22a is calculated based on detection data corresponding to each subject portion 22a, and each unit area is set based on the body thickness. Details will be described below.

From Equation 5 and Equation 6, the following equation is obtained.
Since the density ρ of the soft tissue is a known value (substantially the same as that of water) and the mass absorption coefficient μ ′ _HS is a known value as described above, Equation 7 represents the attenuation amount (R _H ) indicates that the body thickness is obtained. Specifically, the body thickness for each subject portion 22a is obtained based on the attenuation amount of the high energy X-ray detected for each subject portion 22a.

  When the body thickness of each subject portion 22a is obtained, the unit area corresponding to each subject portion 22a can be set based on the body thickness. That is, unlike the conventional case, it is possible to set a different unit area corresponding to the body thickness for each subject portion 22a. In the present embodiment, the unit area (the area of the virtual measurement surface) corresponding to each subject portion 22a is set by setting the position of the virtual measurement surface 50 defined in each subject portion 22a based on the body thickness. Set suitably.

The distance between the point light source 30a and the mounting surface 20a of the imaging table top plate 20 is L ₁ , the distance between the mounting surface 20a and the virtual measurement surface 50 is L ₂ , and the point light source 30a and the X-ray detector 32 are used. distance L _3, and the length of the spreading direction of the fan beam of each detector element 32a (x-axis direction) is denoted by d _x, the length of the x-axis direction of the virtual measurement surface 50 between the sensing element surface 32b of the (Δx in FIG. 4) is obtained by the following equation.

In the present embodiment, each virtual measurement surface 50 for each subject portion 22a is set to the center position in the body thickness direction of each subject portion 22a. Since the body thickness of each subject portion 22a is calculated by Equation 7, the distance between the placement surface 20a and each virtual measurement surface 50 set at the center position in the body thickness direction of each subject portion 22a is:
It is represented by Δx obtained by substituting Equation 9 into Equation 8 is the length of the virtual measurement surface 50 in the x-axis direction.

  Δy, which is the length in the y-axis direction of each virtual measurement surface 50, is the same as in the prior art by the point light source 30a (X-ray irradiator 30) and the X-ray detector 32 before detection data is obtained in all the detection elements 32a. The distance moved in the y-axis direction. Then, by multiplying the calculated Δx and Δy, the area of each virtual measurement surface 50, that is, the unit area regarding each subject portion 22a is calculated.

  As shown in FIG. 4, since the X-rays emitted from the point light source 30a have a beam shape that spreads in the left-right direction, the area of the virtual measurement surface 50 defined in the subject portion 22a (more specifically, virtual The length of the measurement surface 50 in the left-right direction) decreases as the distance from the point light source 30a decreases, and increases as the distance from the point light source 30a increases. Each areal density calculated for each subject portion 22a is calculated based on X-rays transmitted through the whole subject portion 22a. Accordingly, it is preferable to set the average length of the lengths in the left-right direction of the different subject portions 22a at the respective positions in the vertical direction as the length in the left-right direction of the virtual measurement surface 50. The average length in the left-right direction of each subject part 22a is the center position of each subject part 22a in the body thickness direction. Therefore, the mass of the subject is calculated with higher accuracy by setting the virtual measurement surface at the center position in the body thickness direction of each subject portion 22a.

  According to Equation 7 described above, the body thickness of each subject portion 22a is calculated based on each detection data (attenuation amount of high energy X-rays). The calculated body thickness of each subject portion 22a (that is, the body thickness of the subject 22) can be used for various processes. For example, in view of the fact that X-ray measurement cannot be suitably performed on a subject having a body thickness that is too thick (for example, a subject having a body thickness of 20 cm or more), the body thickness calculated by Equation 7 above is a predetermined value. A warning can be output to the measurer when the value exceeds. The measurer who confirmed the warning can grasp that the detection data obtained by scanning the subject with X-rays may not be appropriate. The warning is performed by displaying an error on the display unit of the measurement terminal 40 in accordance with an instruction from a control unit (not shown) of the measurement terminal 40. Alternatively, in addition to or instead of this, the control unit of the measurement terminal 40 emits sound or light in the measurement terminal 40 or the X-ray irradiation detector 10.

  The warning may be output at the time of analysis of the detection data after the subject 22 is scanned with X-rays, or the body thickness of each subject portion 22a may be determined in real time (that is, during X-ray scanning). ) If calculated, it may be output during X-ray scanning. When a warning is output during X-ray scanning, it is preferable to immediately stop the X-ray irradiation from the X-ray irradiator 30 together with the warning output from the viewpoint of avoiding unnecessary exposure on the subject 22. .

  As described above, according to the present embodiment, an appropriate unit area corresponding to the body thickness is set for each subject portion 22a. Thereby, the mass (element unit mass) of each subject portion 22a depends on the body thickness as compared with the case where the mass of the subject is calculated by setting the unit area for each subject portion uniformly. Calculation is performed with higher accuracy, and as a result, the mass of the entire subject 22 is calculated with higher accuracy.

  As mentioned above, although embodiment which concerns on this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the meaning of this invention. For example, in the present embodiment, fan beam-shaped X-rays are used, but when mass is calculated using beam-shaped X-rays that spread in the traveling direction, such as a cone beam or a pencil beam, for example, The present invention can be preferably applied. In the present embodiment, fan-beam-shaped X-rays (that is, beams that spread in one direction) are used. Therefore, the side length correction of the virtual measurement surface is performed only in the x-axis direction. When a beam that spreads in two directions is used as described above, the length correction of the sides of the virtual measurement surface is performed in two directions of the x-axis and the y-axis. In that case, the length correction in the y-axis direction is realized by the same processing as described above.

  In an X-ray measurement apparatus using pencil beam-shaped X-rays, the X-ray irradiator and the X-ray detector are sequentially placed in the y-axis direction (depth) in each line aligned in the x-axis direction (left-right direction) of the irradiation region. Direction) (zigzag scanned). At this time, since the pencil beam also has a beam spread in the x-axis direction to some extent, the length of the virtual measurement surface is corrected in the x-axis direction by applying the present invention.

  In the present embodiment, since the mass (element unit mass) of each subject portion 22a is calculated individually, the mass of an arbitrary region (portion) of the subject can be calculated. For example, by adding only the element unit masses of the subject portion 22a included in the ROI designated by the measurer, the mass of the subject in the portion designated as the ROI can be calculated.

  Further, in the present embodiment, the X-ray irradiation detector 10 and the measurement terminal 40 are separated, but the functions of the calculation unit 42 and the storage unit 44 included in the measurement terminal 40 are incorporated in the X-ray irradiation detector 10. Forms can also be employed.

  1 X-ray light source, 3, 3a, 32a detection element, 3b, 32b detection element surface, 5, 22 subject, 5a, 22a subject part, 7, 50 virtual measurement surface, 9 detection data group, 9a detection data, 10 X-ray irradiation detector, 12 base part, 14 arm part, 16 wall part, 18 photographing stand, 20 photographing stand top plate, 20a mounting surface, 24 X-ray irradiation detector top plate, 26 housing box, 30 X-ray irradiator , 30a Point light source, 32 X-ray detector, 34 scanning unit, 36 control unit, 40 measurement terminal, 42 calculation unit, 44 storage unit.

Claims (6)

An X-ray irradiator that irradiates a subject with X-rays having a divergent beam shape;
An X-ray detection element that detects the X-ray transmitted through the subject and outputs detection data;
The area density of the subject part included in the transmission region of the X-ray detected by the X-ray detection element, which is specified from the detection data output by the X-ray detection element, and the unit area calculated according to the detection data And a mass calculation unit for calculating the mass of the subject based on the element unit mass,
An X-ray measurement apparatus comprising: A plurality of the X-ray detection elements are provided, and the plurality of X-ray detection elements output a plurality of the detection data,
The mass calculator calculates the element unit mass for each of the X-ray detection elements, and calculates the mass of the subject as a sum of a plurality of element unit masses calculated for the plurality of X-ray detection elements.
The X-ray measuring apparatus according to claim 1, wherein: The unit area is calculated based on the body thickness of the subject portion calculated based on the detection data output by the X-ray detection element.
The X-ray measuring apparatus according to claim 1 or 2, wherein The unit area is defined as a center position in the body thickness direction of the subject portion, and is calculated as an area of a virtual measurement surface that is a surface parallel to the detection surface of the X-ray detection element.
The X-ray measuring apparatus according to claim 3, wherein: Warning means for outputting a warning when the body thickness of the subject portion calculated based on the detection data output by the X-ray detection element is equal to or greater than a predetermined value;
The X-ray measurement apparatus according to claim 1, further comprising: Computer
The object portion included in the X-ray transmission region detected by the X-ray detection element, which is specified from the detection data output by the X-ray detection element that has detected the X-ray transmitted through the object and having a divergent beam shape A mass calculating means for calculating an element unit mass by multiplying the area density of the element and a unit area calculated according to the detection data, and calculating the mass of the subject based on the element unit mass;
X-ray measurement program characterized in that it functions as