JPH0484939A - Method and device for measuring bone - Google Patents

Abstract

PURPOSE:To effectively eliminate a random noise by smoothing a density pattern of the bone concerned to be examined, in an area A of the part to be examined of an inputted image, and in a wider area B containing the area concerned. CONSTITUTION:For instance, in the case a middle position of a second middle hand bone from reference points 32, 33 and 34 is the part to be examined, a smoothing patter is derived by setting width of an area A of the part to be measured to, for instance, <=1.3mum as shown as 35, shifting it by 65.5mum each in the extreme vicinity and adding suitable weight to plural pieces of transmission light quantities corresponding to each other with regard to each transmission light quantity pattern running along plural scanning lines and executing such smoothing as arithmetical mean, etc. Also, as shown as 36, with regard to the part B to be measured, as well, the smoothing pattern is executed. It is better that the number of pieces of scanning lines is large, but if it is increased, the part to be examined becomes blurred, therefore, in order to obtain the resolution of the transmission light quantity of 0.1mm, it is necessary to reduce a noise to <=0.05mm, and accordingly, it is simple and desirable that about 21 pieces are averaged by the same weight at an interval of 63.5mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an improved needle position measuring method and bone measuring device. More specifically, the present invention provides a method and apparatus for performing accurate bone measurement by combining smoothing of the density pattern of an image of a bone to be examined and conversion to the thickness of a reference material.

[Prior art] Various methods such as confirming the developmental state of human bones and the degree of aging, determining the type of bone lesions such as osteoporosis and osteomalacia, and confirming the progress of the symptoms and the effectiveness of treatment. Bone measurements may be performed.

Such bone measurement methods include the MD method (" Bone Metabolism” Volume 13, 187-
p. 195 (1980), “Bone Metabolism-Volume 14, 91
104 (1981), etc.), and photon absorption geometry, in which bone measurement is performed by irradiating gamma rays onto the bone to be examined and measuring the amount of transmitted gamma with a detector.

The MD method has been adopted because it uses an X-ray photographic film that can be easily obtained using an X-ray imaging device that is widely used as a device for cutting fractures, etc., and is becoming increasingly popular. . Furthermore, photon absorption geometry
During this period, it cannot be said that the devices used to generate gamma radiation are generally more widespread than X-ray imaging devices.

[Problems to be Solved by the Invention] In conventional bone measurement using the MD method, reference points necessary for bone measurement are manually determined on the pre-examination image on an X-ray photographic film, and further, the reference points are determined using the reference points. A site (for example, a site on a transverse line at the midpoint of the long axis of the second metacarpal) is selected for bone measurement in detail using the established method.

Next, while scanning the selected area with a microdensitometer, the intensity of the transmitted light obtained by irradiating the area with light is measured, and the intensity or absorbance of the transmitted light corresponding to the operated area is measured. Have the students draw the line diagram on the designated chart paper. Furthermore, an aluminum staircase standard material (hereinafter referred to as aluminum staircase) was X-rayed together with the test bone.
A microdensitometer is scanned over the vertical line of the image on the film, and the intensity or absorbance diagram of the transmitted light obtained is also written on chart paper. Input the absorbance diagrams of the absorbance of the test bone and the absorbance of the aluminum stairs on the chart paper into the computer using a digitizer, and convert the absorbance of the test bone at each point into the number of steps of the aluminum stairs. do. Using the image thus converted, various indices representing the bone morphology at the target site are calculated within the computer, and the calculation results are output.

However, in cases where images on X-ray film are automatically read, in order to perform bone measurements more quickly and accurately, it is necessary to make appropriate corrections when using the read data. is necessary.

[Means for Solving the Problems] As a result of intensive research to solve the problems and perform bone measurements more quickly and accurately, the present inventors have developed a scanning method that attempts to perform bone measurements on input images. We found that it is effective to perform smoothing in the direction of the line and in the direction perpendicular to the direction of the scanning line by changing the measured area appropriately according to the measurement parameters, and if necessary, to combine both smoothing in the direction of the scanning line. Heading: What led to the present invention.

That is, the present invention includes (a) an image input step for inputting an image based on a transmitted radiation image obtained by irradiating a bone to be examined with radiation, and (b) a region of the examined part in the input image. Obtain density patterns of the bone to be examined along a plurality of different substantially parallel measurement lines in each of A and a wider region B that includes the region A, and measure the plurality of density patterns at respective corresponding positions. a step of obtaining two types of first smoothing patterns corresponding to each region A and H by smoothing;
c) a conversion step for converting the smoothed concentration pattern into the thickness of the standard substance to obtain a conversion pattern; (d)
If necessary, before or after the conversion step, a second smoothing pattern is obtained by smoothing values at multiple points in the vicinity of the first smoothing pattern or the conversion pattern along the measurement line. and (e) further comprising the step of performing calculations for measuring the bone to be examined using the conversion pattern or second smoothing pattern obtained in this way.

Further, the present invention provides such a bone measurement method, wherein the image input step is obtained by irradiating light onto an X-ray photographic film of the bone to be examined, which has been photographed together with a standard material having a varying thickness. This is an image reading step by detecting the amount of transmitted light, and the conversion step is a step of converting the density pattern into the thickness of the standard material based on the relationship between the thickness of the standard material obtained from the X-ray photographic film and the amount of transmitted light. Contains things.

The present invention also includes: (a) an image input means for inputting an image based on a transmitted radiation image obtained by emitting radiation to a bone to be examined; and (b) a region of a part to be examined in the input image. In each of A and a wider region B that includes the region A, smooth the plurality of density patterns of the bone to be examined at respective corresponding positions along a plurality of different substantially parallel measurement lines. A first smoothing pattern is then used to obtain two corresponding first smoothing patterns for each area A and B.
a smoothing means; (e) a converting means for converting the smoothed density pattern into the thickness of the standard substance to obtain a converted pattern; and (d) converting the first smoothed pattern or a second smoothing means for obtaining a second smoothing pattern by smoothing values at a plurality of points in the vicinity of the conversion pattern along the measurement line; (e) further smoothing the conversion pattern or the second smoothing pattern; The present invention includes a bone measuring device characterized by having a calculation means for performing calculations for measuring the bone to be examined using a pattern.

Further, the present invention provides an amount of transmitted light obtained by irradiating light onto an X-ray photographic film of the bone to be examined, which is photographed together with a standard material having a varying thickness, in the bone measuring device. an image reading means for detecting and reading an image, and the converting means converts the density pattern into the thickness of the standard material based on the relationship between the thickness of the standard material obtained from the X-ray photographic film and the amount of transmitted light. Includes things that are means.

Further, the present invention provides that in the bone measuring device, the image input means is a means for inputting an image obtained by detecting a transmitted radiation dose obtained by irradiating the bone to be examined with radiation; This includes a method in which the conversion means converts the density pattern into the thickness of the standard material based on a pre-input relationship between the amount of transmitted radiation obtained by irradiating the standard material with radiation and the thickness of the standard material.

Hereinafter, the bone measurement method and apparatus of the present invention will be explained in more detail.

That is, in the present invention, an image based on a transmitted radiation image obtained by irradiating a bone to be examined with radiation is used, and preferable examples of such radiation include γ-rays of Xll. Examples of transmitted radiation images include images expressed by the shading of shadows on an X-ray photographic film, as well as images obtained by detecting the amount of transmitted radiation, such as the intensity of the transmitted radiation itself. Furthermore, when an X-ray photographic film is used in the present invention, an aluminum staircase is usually used as the standard material having varying thickness, but a slope-shaped aluminum member may also be used. In addition, when using an image obtained by detecting the transmitted radiation itself, for example, an aluminum phantom with a shape similar to the bone to be examined is used as a standard material.
It is desirable to obtain the transmitted radiation image in advance and obtain the relationship between the transmitted radiation dose and the aluminum thickness.

The bone to be examined, which is the object of the bone measurement of the present invention, may be any bone that can be obtained from an X-ray film with a certain degree of clear shading, but usually the soft tissue layer is thin and averaged. portion is preferable. More specifically, flattened and humerus;
Radius 1 ulna, femur.

Examples include placement of the tibia, fibula, etc. Among them, the first metacarpal is practically preferred. Examples of other cancellous bones include the calcaneus, vertebrae, and the end of a canal, among which the calcaneus is practically preferred.

FIG. 1 shows an example of the arrangement when X-ray photography is performed with aluminum stairs in a horizontal position. In the same figure, 10
is a dry plate for X-ray photographic film, 11 is an aluminum staircase, 12 and 13 are the right hand and left hand, respectively, and 14 is the
It is a metacarpal bone.

Inputting the transmitted light image in the needle measuring method and bone measuring device of the present invention involves image reading performed by irradiating light onto the images of the test bone and standard material in the X-ray photographic film and detecting the amount of transmitted light. Alternatively, an image of the amount of transmitted radiation lti itself obtained by irradiating the bone to be examined with X-rays or γ-rays may be input, which is detected by a detection means such as a secondary electron multiplier.

When using an X-ray photographic film, more specifically, for example, a means for generating light (light source) to irradiate the X-ray photographic film.
, a detection means for detecting the intensity of the transmitted light from the light source transmitted through the X-ray photographic film, and an automatic reading means equipped with an automatic film running means for automatically running the X-ray photographic film. It is desirable to use this method to increase efficiency. Note that reading may be performed manually.

Such a light source may be one that generates spot-shaped light, but spot-shaped sources usually require scanning means, and in order to create a device with a small and simple structure, it is necessary to generate band-shaped light. A band-shaped light source for this purpose is practically suitable. Further, as the detection means, any device may be used as long as it can detect transmitted light and automatically read it, but when a strip-shaped light source is used, a strip-shaped sensor, that is, a line sensor is preferable, and a strip-shaped contact image sensor is particularly preferable. Practically preferred. Rollers are usually used as the means for transporting the film, and a pair of rollers rotating in opposite directions with the film sandwiched therebetween is preferably used, but other means may also be used.

FIG. 2 schematically shows an example of such automatic reading means, in which 20 is an X-ray photographic film;
1 shows an image of the bones of the right hand, 22 is a band-shaped light source, 23 is a contact image sensor, and 24 is a roller for running the film.

A specific example of such a strip-shaped light source is a strip-shaped LED (lig
Examples include a high-frequency lighting bar-shaped fluorescent tube, a DC lighting bar-shaped lamp, and a strip-shaped light source in which the end surfaces of optical fibers are arranged in a band shape and the lamp is irradiated from the opposite end surface. In addition, a strip-shaped lens means such as a rod lens using an optical fiber is placed between the strip-shaped light source and the strip-shaped light source so that the light from the strip-shaped light source passes through the X-ray photographic film and is focused at the detection part of the strip-shaped detection means. It is preferable to arrange it between the detection means, preferably between the film and the detection part.

A specific example of a contact image sensor that is a means for detecting transmitted light is a CCD (charge sensor) that is a line sensor.
(coupled device), etc.

Note that the storage means stores a data group in which digital signals relating to the intensity of transmitted light in the image of the X-ray photographic film of the bone to be examined obtained by the automatic reading means or the like are associated with the digits of the film. is desirable.

The means may be of any type as long as it can be memorized, and the storage memory size is selected depending on the purpose of bone measurement.A specific example is 2M bytes for bone measurement of the first metacarpal bone. Examples include computer means such as image memory of a certain degree.

In addition, the needle position measurement method of the present invention has a plurality of different substances in each of the region A of the test part and the wider region B including the region A, for the image of the test bone input or read as described above. By obtaining density patterns along the upper parallel measurement lines and smoothing the values of those density patterns at corresponding positions, two corresponding first smoothing patterns are obtained for each region A and B. The bone measuring device of the present invention has a smoothing means for this purpose. Note that the density pattern refers to a representation of the amount of transmitted light and the amount of transmitted radiation at each point along each measurement line in a read image, either as is or in a digitally converted state. Smoothing means an arithmetic average, an average taking weight into consideration, or the like.

Note that the areas to be measured are not limited to A and B, but the number of areas may be increased as necessary, and the first smoothing pattern corresponding to these areas may be obtained to perform measurement with higher accuracy. It can be done.

A specific example of such first smoothing is as shown in FIG. That is, the figure is an example of an embodiment of the bone measuring device of the present invention, and illustrates an example of an image when an image display means for displaying a read image is provided. The image display means may be of any type as long as it can display as an image a data group consisting of the relationship between digital signals and positions stored in the image storage means or obtained by the automatic reading means. , Specifically, from the viewpoint of resolution and cost, CRT (
cathode ray tube), etc.

It is practically preferable to use the data stored in the image storage means. Further, it is preferable that the displayed image be enlarged to a size larger than that of the image on the X-ray photographic film, since this makes it easier to input the reference points.

FIG. 3 is an example of the second metacarpal bone enlarged and displayed on an image display means such as a CRT. 30 is a display screen;
1 is an image of the second metacarpal bone, and 32.33° 34 indicates the position of the reference point required for bone measurement. A specific example of the point input means is a cursor position display/instruction control means.

The first smoothing pattern in the present invention is, for example, when the area to be measured is an intermediate position between the reference points 32, 33, and 34 in FIG. For each transmitted light amount pattern along multiple scanning lines with a width of, for example, 1.3 mm or less and shifted by 63.5 μm in the vicinity, the arithmetic average of the corresponding multiple transmitted light amounts is given with appropriate weight. It can be obtained by smoothing the equation. Further, as shown at 36, a smoothing pattern can also be applied to the portion B to be measured. By performing such smoothing processing, random noise in the transmitted light pattern can be effectively removed without reducing the spatial resolution.

The number of scanning lines used for smoothing in the area A may be determined as follows, for example. That is 6
In an image reading device with a resolution of about 5 μm, due to X-ray scattering and particle unevenness in the X-ray film, the amount of transmitted light is 174 to 1
There is random noise of about 75 mm, that is, about 0.2 to 0.25 mm. Here, random noise decreases in inverse proportion to the square of the number of averaged lines, so the more scanning lines the better, but if you increase the number of scanning lines, the area to be examined will become blurry, so in order to obtain a resolution of 0.1 mm of transmitted light amount, Since it is necessary to reduce the noise to 0.05 mm or less, it is simple and preferable to average about 21 lines at 63.5 μm intervals with the same weight.

The first smooth pattern thus obtained for region A (width 1 jmm) is used to obtain the values of parameters that obviously change at the position of the scanning line due to changes in bone shape, such as bone width. This is desirable.

This is because the area A is set to an appropriate range without becoming too wide and reducing accuracy.

The number of scanning lines used for smoothing in region B may be any number that covers a wider range than region A, if necessary. For example 6
317.5 μm spacing, which is 5 times 3.5 μm, i.e. 63
．． It is desirable to use 21 scanning lines with five scanning lines spaced at intervals of 5 μm. In this example, the number of scanning lines for region B, which is five times the width of region A (<6.7 nwn), is set to 21, the same as for region A, and the calculation time is kept short to maintain improved measurement efficiency. can be achieved.

The primary smoothing pattern thus obtained for the wide area B is preferably used when obtaining values of parameters that are susceptible to random noise in images, such as bone density, for example.

In the present invention, when using an X-ray photographic film, the first smoothed transmitted light amount pattern for the bone to be examined thus obtained is based on the relationship between the thickness and the transmitted light amount for the standard material read as described above. Then, a conversion pattern is obtained by converting to the thickness of the standard material. In this way, by converting the transmitted light amount pattern into the standard material thickness before performing calculation processing for bone measurement, it is possible to effectively eliminate the influence of differences in the imaging conditions of X-ray photographs.

Furthermore, when using an image obtained by detecting the transmitted radiation itself in the present invention, the relationship between the thickness of the standard material obtained using a phantom as a standard material and the amount of transmitted radiation is input into the device and stored in advance, and It is practically desirable to obtain transformation patterns based on relationships.

Further, in the present invention, if necessary, smoothing processing such as a moving average is performed on the values of a plurality of points in the scanning line direction on the first smoothed transmitted light pattern described above after the conversion pattern or in some cases. A second smoothing pattern may be obtained. Combining such second smoothing such as moving average is advantageous in practice, since high-frequency noise components can be efficiently removed in a two-dimensional manner, and calculations for bone measurement can be performed with high precision. In actual bone measurement, it is preferable to take a moving average of about 11 pieces, since it is unnecessary to use pieces that change at a cycle of 0°5 mm or less.

Note that when a second smoothing pattern is obtained for the first smoothing pattern, it is necessary to further convert the first smoothing pattern into a conversion pattern. Practically speaking, it is preferable to obtain a conversion pattern for the first smoothing pattern and then use it as a second smoothing pattern.

The bone measuring device of the present invention is equipped with a first smoothing means, a converting means, and a second smoothing means as necessary for performing such processing. Computer - means can be mentioned.

Bone measurement in the present invention involves performing calculations necessary for bone measurement based on the thus obtained smoothing pattern or conversion pattern regarding the subject.

Specific examples of calculations for bone measurement include the calculations shown in Figure 4, but there are also various methods of bone measurement that apply the MD method (for example, Japanese Patent Laid-Open No. 59-89
No. 35, JP-A-59-49743, JP-A-6
0-83646, JP-A-61-109557, JP-A-62-183748, etc.) can also be applied.

Figure 4 shows a pattern of stored data on the transverse line of the midpoint of the long axis of the second metacarpal as illustrated in Figure 3, in order to show a specific example of the content of the calculation. . Note that FIG. 4 may be displayed upside down. In the figure, D indicates the bone width, and the shaded area represents the bone density distribution. dl,
d2 indicates the bone cortical width, and d indicates the bone marrow width.

GSML has a peak of 40. It corresponds to the minimum value of the trough 42 between the beaks 41 and indicates the density of (bone cortical bone marrow), G S maxi , G S max2
corresponds to the maximum value of each peak portion. ΣGS corresponds to the total area of the shaded area regarding the width (see "Bone Metabolism" Vol. 4, pp. 319-325 <1981))
.

As a more preferable embodiment of the bone measuring method or bone measuring device of the present invention, there is one in which automatic detection of peak portions such as peaks 40 and 41 in FIG. 4 is performed as follows. That is, in the conversion pattern or the second smoothing pattern as described above, the slope in the global area is determined to avoid erroneously detecting a small peak due to noise as a peak, and the point where the slope changes from positive to negative is determined as the peak. It is designed to detect the area.

As a specific example of such peak detection, when using an X-ray photographic film, the following method can be mentioned.

That is, first, in order to eliminate the influence of noise when finding the first peak 40, a smoothed difference as shown in the following formula (1) is taken, and j-α dDATA(j) =Σ 1=j-a-β DATA (i + j + α + β - Σ DATA (i) i; j + α Looking at the following formula (2), DATA (j) is near the peak.

...(1) The position where dDATA (j-1) ≦O and dDATA (j+1)≧0 ...(2) Here, DATA (j) is the amount of transmitted light at position j, and α .

It is preferable that β be determined based on the resolution of the apparatus, the size of the noise component, and the size of the object to be examined. In reality, it has a spatial resolution of about 65 μm! Then α-4 and β-17 are suitable. Furthermore, if the maximum value is searched again around this area, a more accurate peak can be detected.

When one peak is found, it is preferable to perform a process in which 41 is not regarded as the first peak, and if the peak is not updated within a certain region γ after a peak is found, that point is treated as a peak. γ is determined from the distance between the peaks of the test area, and γ=20 is practical. Similarly, peak 41
seek. Then, 42 is determined as the minimum value between peaks 40 and 41.

Further, as a preferred embodiment of the bone measurement method or apparatus of the present invention, for example, the baseline 43 in FIG. 4 may be determined as follows.

That is, for convenience, in FIG. 5, which is an upside-down version of FIG. 4, and FIG. 6, which is an enlarged example of the left end of FIG.
An inflection point 51 is determined using the maximum second-order difference, and left and right soft tissue lines 53 are determined by performing linear regression on X pieces of data outward from this point and 1 to y pieces of data at a distance. Similarly, regarding the rising portion on the other end side, the soft tissue line 54
Determine.

Next, two pieces of data are taken inward from each inflection point 51.52, linear regression is performed, and the straight line with the maximum slope is the tangent line 55.56. and lines 53 and 55.5 respectively
Let the intersection of 4 and 56 be 57.58, respectively, and the point 57°5
8 is the baseline 43 illustrated in FIG.
shall be.

In this case, it is practically desirable to set x=8, y=20, and z=16.

FIG. 7 shows the detection of the peak portion and the baseline correction from the smoothed pattern obtained by performing the first smoothing and the second smoothing using the data regarding the 21 scanning lines obtained for the area A. This is an example of a flowchart for performing detection. Such results are determined by the bone measurement calculation routine, for example, d, dl, dz in FIG.
, D, etc.

FIG. 8 is a flowchart for detecting peaks and baselines in the same manner as above using data regarding 21 scanning lines obtained for region B, which is five times wider than region A. This is an example. This result is obtained by the bone measurement calculation routine, for example, GS-t shown in FIG. , G S maxi,
This is useful for determining values such as G S max21ΣGS.

Here, FIG. 9 illustrates the relationship between the width [l1II+1] of region B and the CV value for each of the resulting GSa+In+ΣGS/D. From this example, the width of area B is 3rrrrn
The following shows that accurate measurement of these parameters is difficult.

In addition, the width between the scanning lines in the region B, that is, the number of scanning lines at intervals of 63.5 μm between the scanning lines, and GS1, GS, n,
FIG. 10 shows the relationship between CV values for each parameter of , and ΣGS/D. In particular, when looking at G S m, , if the number of scanning lines at 63.5 μm intervals becomes too sparse (10 or more), the CV value increases and the measurement accuracy tends to worsen, which is not desirable. be exposed.

It is practically preferable that the bone measurement device of the present invention includes means for outputting bone measurement results such as calculation results. The output means may be of any type as long as it can output the measurement results obtained by calculation, and specific examples include dot type ink printers, thermal printers, laser printers, video printers, and other CRTs for hard copies. Examples include screens. For example, a method that can display bone density distribution in different colors as disclosed in Japanese Patent Application Laid-Open No. 109557/1984 is an example of a method that is practically preferable.

As shown in the above-described specific example, the present invention is not only applicable to image data obtained from an X-ray film, but also includes providing an image sensor in an X-ray imaging device and converting image signals from the sensor into an A/D converter. It can also be applied to image data obtained by converting and storing it in memory.

[Effects of the Invention] According to the needle position measuring method and bone measuring device of the present invention, the scanning line that is the basis for smoothing is made accurate, the influence of differences in radiographic conditions is eliminated, and An excellent effect can be obtained in that bone measurement can be performed with high accuracy by effectively removing the noise caused by the noise.

[Brief explanation of the drawing]

FIG. 1 illustrates the arrangement of a subject during X-ray photography to obtain the X-ray photographic film used in the present invention. FIG. 2 schematically illustrates a reading means in the apparatus of the present invention, and FIG. 3 illustrates an image of an image display means that may be included in the apparatus. FIG. 4 schematically illustrates calculations for bone measurement that can be performed in the apparatus of the present invention. FIG. 5 is an example of the pattern shown in FIG. 4 turned upside down, and FIG. 6 is an example of the left end portion enlarged. FIG. 7 illustrates a flowchart of smoothing, peak detection, and baseline detection for region A in the present invention, and FIG. 8 illustrates a similar flowchart for region B. Further, FIG. 9 illustrates the influence of the width of region B in the present invention, and FIG. 10 illustrates the influence of the scanning line spacing of region B in the present invention. Figure 1 Figure z Figure 1

Claims (5)

[Claims] (1) (a) An image input step for inputting an image based on a transmitted radiation image obtained by irradiating the examined bone with radiation, and (b) an image input step for inputting an image based on a transmitted radiation image obtained by irradiating the examined bone with radiation; In each area B that includes area A and is wider than area A,
By obtaining the density patterns of the bone to be examined along a plurality of different substantially parallel measurement lines and smoothing the plurality of density patterns at respective corresponding positions, two corresponding two (c) a conversion step of converting the smoothed concentration pattern into the thickness of the standard substance to obtain a conversion pattern; (e) obtaining a second smoothing pattern by smoothing values at multiple points in the vicinity of the first smoothing pattern or the conversion pattern along the measurement line before or after the conversion step; A bone measuring method further comprising the step of performing calculations for measuring the bone to be examined using the conversion pattern or second smoothing pattern obtained in this manner. (2) The image input step is an image reading step by detecting the amount of transmitted light obtained by irradiating light onto an X-ray photographic film of the test bone taken together with a standard material of varying thickness. 2. The bone measuring method according to claim 1, wherein the conversion step is a step of converting the density pattern into the thickness of the standard material based on the relationship between the thickness of the standard material obtained from the X-ray photographic film and the amount of transmitted light. (3) (a) Image input means for inputting an image based on a transmitted radiation image obtained by emitting radiation to the examined bone, and (b) region A of the examined part of the input image. and a region B that includes the region A and is wider than the region A,
The plurality of density patterns of the bone to be examined are smoothed at corresponding positions along a plurality of different substantially parallel measurement lines, and two types of first a first smoothing means for obtaining a smoothed pattern; (c) a converting means for converting the smoothed concentration pattern into a thickness of the standard substance to obtain a converted pattern; and (d) as necessary. (e) having a second smoothing means for smoothing values at a plurality of points in the vicinity of the first smoothing pattern or the conversion pattern along the measurement line to obtain a second smoothing pattern; A bone measurement device further comprising calculation means for performing calculations for measuring the bone to be examined using the conversion pattern or the second smoothing pattern. (4) The image input means reads an image by detecting the amount of transmitted light obtained by irradiating light onto an X-ray photographic film of the test bone photographed together with a standard material of varying thickness. 4. The bone measurement method according to claim 3, wherein the bone measurement device is an image reading means, and the converting means is means for converting a density pattern into the thickness of the standard material based on the relationship between the thickness of the standard material obtained from the X-ray photographic film and the amount of transmitted light. Device. (5) The image input means is means for inputting an image obtained by detecting the amount of transmitted radiation obtained by irradiating the test bone with radiation, and the conversion means irradiates the reference material with radiation. 4. The bone measuring device according to claim 3, further comprising means for converting the density pattern into the thickness of the standard material based on a pre-input relationship between the transmitted radiation dose obtained by the method and the thickness of the standard material.