JP5676425B2 - Arithmetic processing device and bone density measuring device - Google Patents

Description

  In the present invention, radiation with a predetermined tube voltage is applied to a slope-shaped standard substance and transmitted, and bone density is measured using the correspondence between the detected transmission radiation brightness value and the thickness of the standard substance. The present invention relates to an arithmetic processing device and a bone density measuring device including the arithmetic processing device.

  Conventionally, for example, the MD method, the DIP method, and the like are known as methods for measuring the amount of bone mineral for confirming the growth state of human bones. In the MD method described in Patent Document 1, an aluminum step is imaged under imaging conditions used for imaging a measurement site of a subject by X-rays, and the photoelectric conversion elements constituting the sensor are used by using the imaging results. Correction process of the sensor element and correction process of the temporal change of the sensor element are performed. This shooting condition can be input by the shooting condition input unit, and the input shooting condition is displayed on the shooting condition display unit.

  In the DIP method described in Patent Document 2, an aluminum scale and both palms of a subject are placed on an X-ray film, and imaging is performed using X-rays in which a tube voltage is set to 50 kV. Normally, 50 kV with the best correlation between bone (hydroxyapatite) and aluminum is set as the recommended tube voltage under the imaging conditions of the DIP method.

JP 2006-334046 A Japanese Patent No. 2793502

  In the MD method described in Patent Document 1, detection system correction such as correction processing for variations between photoelectric conversion elements constituting a sensor and correction processing for changes in sensor elements over time is performed, but the display is performed on the imaging condition display unit. Correction of the output system such as processing for correcting the difference between the X-ray tube voltage (hereinafter referred to as display tube voltage) and the X-ray tube voltage actually irradiated (hereinafter referred to as effective tube voltage) is not performed. . Similarly, even in the DIP method described in Patent Document 2, the same output system correction is not performed.

  In X-ray generators installed in hospitals, clinics, etc., there may be a difference between the display tube voltage and the effective tube voltage due to, for example, aging deterioration, etc., which may not be equivalent. In addition, since the height of the X-ray light source and the performance of the X-ray detector may vary depending on the device, the digital value (density) of the detected luminance value may vary greatly depending on the device. .

  In Fig. 1, X-rays (effective tube voltages of 40, 46, 50, 55, and 60 kV) are irradiated onto an aluminum slope that is slope-shaped aluminum, and the intensity of the X-ray that has passed through the aluminum slope is reversed. It is the graph which made the vertical axis | shaft the digital value (density | concentration) of the acquired luminance value, and made the thickness (aluminum position) of the aluminum slope the horizontal axis. Even if the display tube voltage is 50 kV, for example, if the effective tube voltage has decreased to 46 kV due to deterioration over time, the digital value fluctuates greatly as shown in FIG. (Concentration) cannot be obtained.

  In order to determine whether or not the effective tube voltage is appropriate compared to the display tube voltage, it is necessary to measure the effective tube voltage. However, a tube voltmeter known as a device for measuring the effective tube voltage is very Expensive and difficult to introduce.

  Therefore, in the present invention, an arithmetic processing unit and a bone that can evaluate whether or not the tube voltage of the actually irradiated X-ray is more appropriate than the desired tube voltage without using a tube voltmeter. An object is to provide a density measuring apparatus.

In order to solve the above-described problem, an arithmetic processing apparatus according to an aspect of the present invention provides a standard material having a slope-like shape in which radiation from a predetermined tube voltage connects a front end surface and a rear end surface via a bottom surface and a slope. Detected in the arithmetic processing unit that measures the bone density using the correspondence between the detected brightness value of the transmitted radiation and the thickness between the bottom surface and the slope of the reference material. Generation means for performing a calculation for generating a luminance profile indicating a correspondence relationship, and a normalization for performing a calculation for generating a normalized profile by normalizing the luminance profile based on the maximum value and the minimum value of the generated luminance profile means, each of the luminance values corresponding to the respective thicknesses in the direction different positions towards the rear surface from the front end face in the normalized profiles standardization, And having a determining means for performing a calculation for determining whether included in a predetermined range defined by the respective constant tube voltage and the thickness, the.

  According to the arithmetic processing apparatus according to an aspect of the present invention, first, a luminance profile is generated from the luminance value obtained by irradiating the slope-shaped standard material with radiation, and then the maximum value and the minimum value of the luminance profile. A standardized profile is generated based on. Then, it is determined whether or not each of the luminance values corresponding to each of a plurality of different thicknesses in the normalized profile is included in a predetermined range defined by a predetermined tube voltage and each of the thicknesses.

  Thus, instead of using a tube voltmeter, the luminance value corresponding to the tube voltage of the radiation such as X-rays actually irradiated using the luminance value obtained by irradiating the slope standard material with radiation. Is included in a predetermined range corresponding to a desired tube voltage. As a result, it is possible to evaluate whether or not the tube voltage of radiation such as X-rays actually irradiated is appropriate compared to the desired tube voltage without using a tube voltmeter.

  A bone density measuring device according to an aspect of the present invention includes the above-described arithmetic processing device, a placement unit that can place a test bone irradiated with radiation by a predetermined tube voltage, a test bone, and a standard substance. And detecting means for detecting the transmitted radiation.

  According to the bone density measuring apparatus according to one aspect of the present invention, a test bone irradiated with radiation by a predetermined tube voltage is placed on the mounting means, and the radiation transmitted through the test bone and the standard substance is detected. It becomes possible to do.

In the bone density measuring apparatus according to another aspect, the determination unit may determine a luminance value corresponding to a thickness of a position included in a range of 30 mm to 130 mm as a different position in a direction from the front end surface toward the rear end surface. .

  In this embodiment, whether or not the tube voltage of the actually irradiated X-ray is appropriate compared to the desired tube voltage by including a plurality of different thicknesses in the normalized profile in the range of 30 mm to 130 mm. It becomes possible to evaluate more accurately.

In the bone density measuring apparatus according to another aspect, the generation means uses, as a luminance value at the position , an average value of luminance detected in a direction perpendicular to the direction of the position from the front end surface to the rear end surface in the standard substance . An operation for generating a luminance profile may be performed.

  In this form, the average value of the luminance at the same thickness of the standard material is used as the luminance value at the thickness to generate the luminance profile. Thus, since the average value of the luminance of the standard material at the same thickness is used as the luminance value at the thickness, a more appropriate luminance profile can be generated.

  According to the present invention, an arithmetic processing unit capable of evaluating whether or not the tube voltage of the actually irradiated X-ray is appropriate as compared with a desired tube voltage without using a tube voltmeter, and A bone density measuring device can be provided.

It is the graph which made the luminance value obtained by reversing the intensity | strength of the X-ray which permeate | transmitted the aluminum slope the vertical axis | shaft, and made the thickness of the aluminum slope the horizontal axis. It is a perspective view which shows the external appearance of the bone density measuring apparatus which concerns on a present Example. It is the top view and side view explaining the detail of the shape of an aluminum rope. 3 is an X-ray image obtained by detecting X-rays transmitted through an aluminum slope. It is a graph of the brightness | luminance profile obtained by detecting the X-ray which permeate | transmitted the aluminum slope. 6 is a graph of a normalized profile obtained by normalizing the graph shown in FIG. 5. 7 is a graph in which a predetermined range is added to the graph of the normalized profile shown in FIG. 6. It is a graph of the normalization profile which changes with each of five types of effective tube voltages. It is a flowchart for demonstrating the main steps of the bone density measuring method performed in the bone density measuring apparatus which concerns on this embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

(1) Outline of Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 2 is a perspective view showing an appearance of the bone density measuring apparatus 10 according to the present embodiment. As shown in FIG. 2, the bone density measuring device 10 includes a cassette 1 (placement means) on which a test bone H to be measured for bone density (a bone mineral amount determination) is placed, and an upper surface of the cassette 1. The mounted aluminum slope 2, the X-ray source 3 for irradiating the test bone H and the aluminum slope 2 with X-rays (radiation), and the radiation detection for detecting the X-ray transmitted through the test bone H and the aluminum slope 2 And an analyzer 5 (arithmetic processing unit) capable of adjusting the tube voltage of the X-ray source 3 in accordance with the detection result of the radiation detector 4.

  The cassette 1 is a mounting table on which the test bone H and the aluminum slope 2 irradiated with X-rays can be mounted. In order to place the test bone H to be measured on the bone density (bone mineral content) on the cassette 1, for example, the palm of the subject is placed on the cassette 1. The aluminum rope 2 is placed at a predetermined center position of the cassette 1 such that a slope 22 described later is exposed on the surface.

  The aluminum slope 2 is a slope-shaped standard material having a later-described slope 22 having a predetermined inclination. By referring to the photographed image data of the X-rays transmitted through the aluminum rope 2, the analysis device 5 calculates which brightness corresponds to what thickness in terms of aluminum thickness. Details of the shape of the aluminum rope 2 will be described later.

  The X-ray source 3 is an X-ray generator that irradiates the test bone H and the aluminum slope 2 placed on the cassette 1 with X-rays. The X-ray tube voltage applied to the bone H and the aluminum slope 2 can be adjusted by the analysis device 5.

  The radiation detector 4 is a flat panel sensor (solid-state imaging device) that detects the luminance value of transmitted X-rays (transmitted radiation) transmitted through the bone H to be examined and the aluminum slope 2. The detected luminance value indicating the luminance of the transmitted X-ray is transmitted to the analysis device 5.

  The analysis device 5 is a computer device that performs arithmetic processing for measuring the bone density of the bone H to be examined using the correspondence relationship between the detected luminance value of transmitted X-rays and the thickness of the aluminum slope 2. The analysis device 5 estimates the bone density of the test bone H from the aluminum thickness having the same brightness value as the brightness value of the test bone H. The tube voltage that serves as a guide for the X-rays irradiated to the bone H to be examined and the aluminum slope 2 is the display tube voltage (predetermined tube voltage input by the measurer), and the operation unit and display unit of the analyzer 5 Etc. are displayed. The analysis device 5 includes a generation unit 51 (generation unit), a normalization unit 52 (standardization unit), and a determination unit 53 (determination unit).

  The generation unit 51 is a calculation part that performs a calculation to generate a luminance profile (density profile) from the luminance value indicating the luminance of transmitted X-rays detected by the radiation detector 4. The luminance profile is information that defines the correspondence between the thickness of the aluminum slope 2 and the luminance value of transmitted X-rays detected at this thickness.

  In addition, the production | generation part 51 performs the calculation which produces | generates the above-mentioned brightness profile, using the average value of the brightness | luminances detected in the same thickness of the aluminum slope 2 as a brightness value in this thickness. The details of the arithmetic processing using the average value of the luminances detected at the same thickness as the luminance value at this thickness will be described later.

  The normalization unit 52 is a calculation unit that extracts the maximum value and the minimum value of the luminance value in the luminance profile generated by the generation unit 51 and performs an operation for normalizing the luminance profile based on the maximum value and the minimum value. is there. For example, the normalization unit 52 extracts the luminance value at the thinnest portion of the aluminum slope 2 as a minimum value, and assumes that the luminance value (standard value) is 0. If the minimum values do not match, it is determined as NG data.

  Further, the normalization unit 52 divides the luminance value at each thickness of the aluminum slope 2 by the maximum value of the luminance value in the luminance profile to obtain the concentration (standard value) at each thickness of the aluminum slope 2. Asking. As a result, the concentration (standard value) in the thickness of the aluminum slope that gives the maximum value of the luminance value in the luminance profile is 1. As a result of performing the above normalization, a normalized profile is generated in which the concentration (standard value) changes in the range of 0 to 1 with respect to the change in the aluminum thickness. Details of the calculation for generating the normalized profile and details of the normalized profile that varies depending on the effective tube voltage will be described later.

  The determination unit 53 is an operation part that performs an operation to determine whether or not each of the concentrations (standard values) corresponding to each of a plurality of different aluminum thicknesses (aluminum positions) in the standardized profile is included in a predetermined range. is there. The predetermined range is a range defined by the display tube voltage and the aluminum thickness when the tube voltage indicated as the display tube voltage matches the effective tube voltage. For example, when the X-ray display tube voltage is 50 kV, the concentration (standard value) at an aluminum thickness of 70 mm is about 0.58 points. Here, it is assumed that the predetermined range in the case where the display tube voltage is 50 kV and the aluminum thickness is 70 mm is defined by the determination unit 53 to be 0.5 or more and 0.6 points or less. In this case, it is determined that the concentration (standard value) corresponding to the aluminum thickness of 70 mm is included in the predetermined range.

  When each of the luminance values corresponding to each of a plurality of different aluminum thicknesses in the normalized profile is not included in the predetermined range, the determination unit 53 determines that the effective tube voltage is not appropriate compared to the display tube voltage (effective tube voltage). The tube voltage of the X-ray source 3 is adjusted to an appropriate tube voltage. Details of the calculation for determining whether the luminance value is included in the predetermined range will be described later.

(2) Details of Shape of Aluminum Slope Next, details of the shape of the aluminum slope 2 will be described with reference to FIG. FIG. 3 is a plan view and a side view for explaining details of the shape of the aluminum slope 2. The aluminum rope 2 has a substantially wedge shape. That is, the aluminum slope 2 has an inclined surface 22, a front end surface 23, a rear end surface 24, a reference side surface 25, a flat side surface 26, and a bottom surface 27. The front end surface 23 is connected to the rear end surface 24 through the inclined surface 22, the reference side surface 25, the flat side surface 26, and the bottom surface 27.

  Here, the distance L1 from the front end surface 23 to the rear end surface 24 is, for example, 150 mm. A distance L2 from the reference side surface 25 to the flat side surface 26 is, for example, 15 mm. The height L3 of the aluminum slope 2 at the distal end face 23 is, for example, 0.7 mm. The height L4 of the aluminum slope 2 at the rear end face 24 is, for example, 15.4 mm.

  Further, the slope 22 has an inclination in which the thickness increases along the + Y direction (longitudinal direction from the front end face 23 toward the rear end face 24). For example, when it travels 10 mm in the Y direction, it has an inclination such that it travels 1 mm in the Z direction. That is, the slope is such that the ratio of the length in the Y direction to the maximum thickness in the Z direction is 10: 1.

  The reference side surface 25 has a ridge line 25a and a plurality of reference grooves 25b. The reference grooves 25b are provided at intervals in the Y direction, and extend from the slope 22 to the bottom surface 27 along the Z direction. One reference groove 25b is provided at a position separated from the front end surface 23 by a distance L5 in the Y direction, and the distance L5 is, for example, 10 mm. Another adjacent reference groove 25b is provided at a position 10 mm away from one reference groove 25b in the Y direction. That is, the interval L6 between the adjacent reference grooves 25b is 10 mm.

  In the present embodiment, 14 reference grooves 25b are formed along the Y direction. The cross section along the XY plane of the reference groove 25b has a substantially triangular shape. The angle of the apex of the substantially triangular shape that is the cross section of the reference groove 25b is, for example, about 60 °.

  The flat side surface 26 has a ridge line 26 a and is located on the opposite side of the reference side surface 25. The flat side surface 26 is not provided with the reference groove 25b. The bottom surface 27 is formed so as to be orthogonal to the tip surface 23. The bottom surface 27 is formed so as to be orthogonal to the rear end surface 24.

(3) Details of Calculation Processing Using Average Value of Luminances as Luminance Values Details of calculation processing using the average value of luminances as luminance values will be described with reference to FIG. FIG. 4 is an X-ray image obtained by detecting X-rays transmitted through the aluminum slope 2 placed on the cassette 1. In this X-ray image, an arrow indicating the longitudinal direction (Y direction) of the aluminum slope 2 and a luminance value detection range S are additionally written.

  Here, the detection range S in the horizontal direction and the vertical direction in FIG. 4 of the detection range S is fixed. Aluminum detection is performed by straight line detection by Hough transform. In this X-ray image, an area that appears bright is an area with a high luminance value. A region having a high luminance value indicates that the thickness of the aluminum slope 2 is large, for example. An area that appears dark is an area with a low luminance value. A region having a low luminance value indicates that the thickness of the aluminum slope 2 is small, for example.

  The generation unit 51 performs an operation of generating a luminance profile using the average value of the luminances detected at the same thickness (X direction perpendicular to the Y direction) of the aluminum slope 2 as the luminance value at this thickness. .

(4) Details of Calculation for Generating Normalized Profile Next, details of the calculation for generating the normalized profile will be described with reference to FIGS. 5 and 6. FIG. 5 shows the density (luminance value of the brightness value) with respect to the thickness (aluminum position) of the aluminum slope 2 obtained by detecting X-rays (the display tube voltage is 50 kV) transmitted through the aluminum slope 2 placed on the cassette 1. It is a graph of the luminance profile which shows the change of a digital value. FIG. 6 is a graph of a normalized profile obtained by normalizing the graph shown in FIG. The density (digital value of the luminance value) is a value obtained by inverting the intensity of X-rays that have passed through the aluminum slope.

The normalization unit 52 performs an operation for normalizing the luminance profile based on the maximum value and the minimum value of the digital value (density) of the luminance value in the luminance profile shown in FIG. For example, the normalization unit 52 assumes that the luminance value (about 1400 points) in the thinnest portion of the aluminum slope 2 and the density (standard value) is 0 points. Furthermore, the normalization part 52 calculates the density | concentration (standard value) in each thickness of the aluminum slope 2 based on the following Numerical formula (1).
(Equation 1)
Concentration at each thickness (standard value) = (Luminance value at each thickness−Minimum luminance value) ÷ (Maximum luminance value−Minimum luminance value)

  Thereby, the density (standard value) in the aluminum thickness which gives the maximum value of the density (digital value of the brightness value) in the brightness profile is 1 point. As a result of this normalization, a normalized profile having a vertical axis whose density (standard value) is 0 point or more and 1 point or less is generated.

(5) Details of Calculation for Determining Whether Brightness Value is Included in Predetermined Range Details of the calculation for determining whether the luminance value is included in the predetermined range will be described with reference to FIG. FIG. 7 is a graph in which the above-described predetermined ranges R1 and R2 are added to the graph of the normalized profile shown in FIG.

  It is assumed that 70 mm and 100 mm, for example, are selected in advance by the determination unit 53 as a plurality of different aluminum thicknesses in the aluminum rope 2, and the X-ray display tube voltage at this time is, for example, 50 kV. In addition, it is preferable that a plurality of different aluminum thicknesses in the normalized profile are all included in the range of 30 mm to 130 mm. As shown in FIG. 7, the standardization profile obtained by the standardization unit 52 has a density (standard value) corresponding to 70 mm of about 0.58 points and a density (standard value) corresponding to 100 mm. Suppose that it was 0.76 points.

  Here, when the effective tube voltage is around 50 kV (50 kV plus several kV or less which is a specific tube voltage and 50 kV minus several kV or more which is a specific tube voltage), the determination unit 53 is at a position where the aluminum thickness is 70 mm. Is included in a predetermined range R1 of 0.5 to 0.6 points, and the concentration (standard value) at a position where the aluminum thickness is 100 mm is 0.7 to 0.8 points. Range information such as included in the range R2 is stored in advance.

  Then, the determination unit 53 includes 0.58 points of the density (standard value) corresponding to 70 mm included in the predetermined range R1 of 0.5 to 0.6 points and the density (standard value) corresponding to 100 mm. It is determined that 0.76 points are included in the predetermined range R2 of 0.7 to 0.8 points. Then, since each of the plurality of concentrations (standard values) is included in each of the predetermined ranges R1 and R2, the determination unit 53 is more effective than the display tube voltage (effective tube voltage). And the display tube voltage are relatively small).

  The density (standard value) corresponding to 70 mm is less than 0.5 point (or a value greater than 0.6 point), and the density (standard value) corresponding to 100 mm is less than 0.7 point (or 0). In the case of a value greater than .8 points), the determination unit 53 does not include each of the plurality of concentrations (standard values) within the predetermined range, so that the effective tube voltage is not appropriate compared to the display tube voltage. (The difference between the effective tube voltage and the display tube voltage is relatively large).

(6) Details of Normalized Profiles that Depend on Effective Tube Voltage Next, details of the standardized profiles that differ depending on the effective tube voltage will be described with reference to FIG. FIG. 8 is a graph of normalized profiles that differ depending on each of the five types of effective tube voltages of 40, 46, 50, 55, and 60 kV. The vertical axis is a relative value as a concentration (standard value) that is 0 point or more and 1 point or less, and the horizontal axis is the thickness (aluminum position) of the aluminum slope. The determination unit 53 may store in advance the above-described range information determined based on the graph shown in FIG. 8 for each effective tube voltage.

(7) Bone Density Measuring Method Performed in Bone Density Measuring Device Next, a bone density measuring method performed in the bone density measuring device 10 will be described with reference to FIG. FIG. 9 is a flowchart for explaining the main steps of the bone density measuring method performed in the bone density measuring apparatus 10.

  First, when the subject bone H and the aluminum slope 2 are placed on the cassette 1, the X-ray source 3 irradiates the subject bone H and the aluminum slope 2 with X-rays (step S01). Then, the radiation detector 4 detects the luminance value of the transmitted X-ray that has passed through the subject bone H and the aluminum slope 2 (step S02).

  Next, the production | generation part 51 performs the calculation which produces | generates a brightness | luminance profile from the luminance value which shows the brightness | luminance of the transmission X-ray detected by the radiation detector 4 (step S03). Then, the normalization unit 52 performs an operation for normalizing the luminance profile based on the maximum value and the minimum value of the luminance value digital value (density) in the luminance profile generated by the generation unit 51 and generating the normalized profile. Perform (step S04).

  Next, the determination unit 53 performs an operation for determining whether or not each of the concentrations (standard values) corresponding to each of a plurality of different aluminum thicknesses in the standardized profile is included in each predetermined range (Step S53). S05).

  Here, when each of these plural concentrations (standard values) is included in the respective predetermined ranges, the effective tube voltage is appropriate compared to the display tube voltage (the difference between the effective tube voltage and the display tube voltage). Is relatively small), and the series of processing ends.

  On the other hand, when each of these multiple concentrations (standard values) is not included in the respective predetermined ranges, the effective tube voltage is not appropriate compared to the display tube voltage (the difference between the effective tube voltage and the display tube voltage is compared). The process proceeds to step S06 described later.

  In step S06, the determination unit 53 adjusts the tube voltage of the X-ray source 3 to an appropriate tube voltage so that the difference between the effective tube voltage and the display tube voltage becomes smaller. To change. And a series of processings are once ended, and it shifts to Step S01 again. This is repeated until the effective tube voltage becomes reasonable compared to the display tube voltage.

(8) Action and Effect According to the Present Invention According to the analysis device 5, first, a luminance profile is generated from the luminance value obtained by irradiating the aluminum slope 2 with X-rays, and then the maximum value and the minimum value of the luminance profile. A normalized profile is generated based on the value. Each concentration (standard value) corresponding to each of a plurality of different aluminum thicknesses in the normalized profile is displayed (when the tube voltage indicated as the display tube voltage matches the effective tube voltage). It is determined whether or not it is included in a predetermined range defined by the tube voltage and the aluminum thickness.

  Thus, instead of using a tube voltmeter, the luminance corresponding to the tube voltage (effective tube voltage) of the actually irradiated X-ray is obtained using the luminance value obtained by irradiating the aluminum slope 2 with X-rays. It is determined whether or not the value falls within a predetermined range corresponding to the tube voltage (display tube voltage) desired by the measurer. As a result, it is possible to evaluate whether or not the tube voltage of the actually irradiated X-ray is appropriate compared to the desired tube voltage without using a tube voltmeter.

  Further, according to the bone density measuring device 10 including the analysis device 5, the test bone H irradiated with X-rays by the display tube voltage is placed on the cassette 1 and transmitted through the test bone H and the aluminum slope 2. X-rays can be detected.

  In addition, by including a plurality of different aluminum thicknesses in the standardized profile in the range of 30 mm to 130 mm, the difference in relative value (concentration) due to the difference in effective tube voltage becomes clearer as shown in FIG. . For this reason, it is possible to more accurately determine whether or not the effective tube voltage is appropriate (a state in which the difference is relatively small) compared to the display tube voltage (for example, 50 kV).

  In addition, the average value of the luminance at the same thickness of the aluminum slope 2 is used as the luminance value at this thickness to generate a luminance profile. Thus, since the average value of the luminance at the same thickness of the aluminum slope 2 is used as the luminance value at this thickness, a more appropriate luminance profile can be generated.

(9) Modifications The present invention is not limited to the above-described embodiment, and various other modifications are possible. In the above-described embodiment, as illustrated in FIG. 2, a configuration in which the radiation detector 4 and the analysis device 5 are connected by wire and can communicate with each other is illustrated, but an imaging plate is used as the radiation detector 4. The imaging plate and the analyzing device 5 are configured not to be connected by wire, and the reading device (not shown) capable of reading the luminance value detected by the imaging plate is connected to the analyzing device 5 by wire. Also good. A flat panel detector may be used as the radiation detector 4. Further, in the above-described embodiment, the configuration using X-rays as radiation is illustrated, but a configuration using radiation other than X-rays may be used.

  According to the present invention, it is possible to evaluate whether or not the tube voltage of the actually irradiated X-ray is more appropriate than the desired tube voltage without using a tube voltmeter.

  DESCRIPTION OF SYMBOLS 1 ... Cassette, 2 ... Aluminum slope, 3 ... X-ray source, 4 ... Radiation detector, 5 ... Analysis apparatus, 10 ... Bone density measuring device, 22 ... Slope, 23 ... Front end surface, 24 ... Rear end surface, 25 ... Reference | standard Side surface, 25a, 26a ... ridge line, 25b ... reference groove, 26 ... flat side surface, 27 ... bottom surface, 51 ... generating unit, 52 ... normalizing unit, 53 ... determining unit, H ... bone to be examined, L1, L2, L5 ... Distance, L3, L4 ... Height, L6 ... Interval, R1, R2 ... Predetermined range, S ... Detection range.

Claims (4)

Radiation by a predetermined tube voltage is irradiated and transmitted through a standard material having a slope shape such that the front end surface and the rear end surface are connected via the bottom surface and the inclined surface, and the brightness value of the detected transmitted radiation and the standard In an arithmetic processing unit that measures bone density using the correspondence between the bottom surface of the substance and the thickness between the slopes ,
Generation means for performing an operation for generating a luminance profile indicating the correspondence from the detected luminance value;
Normalization means for performing an operation of generating a normalized profile by normalizing the brightness profile based on the maximum value and the minimum value of the generated brightness profile;
Each of the luminance values corresponding to each of the thicknesses at different positions in the direction from the front end surface to the rear end surface in the standardized standardized profile is determined by the predetermined tube voltage and the thickness. A determination means for performing an operation for determining whether or not the predetermined range is included;
An arithmetic processing apparatus comprising: An arithmetic processing device according to claim 1;
A placing means capable of placing the bone to be examined that is irradiated with the radiation by the predetermined tube voltage;
Detection means for detecting radiation that has passed through the bone to be examined and the standard substance;
A bone density measuring device comprising: The said determination means determines the luminance value corresponding to the said thickness of the position included in the range of 30 mm-130 mm as a position where the direction which goes to the said rear end surface from the said front end surface differs. The bone density measuring apparatus described. The generating means uses an average value of luminance detected in a direction perpendicular to the direction of the direction from the front end surface to the rear end surface of the standard material as the luminance value at the position , and The bone density measuring apparatus according to claim 2 or 3, wherein a calculation for generating a profile is performed.