JP2732979B2 - Bone measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bone measuring device. More specifically, the present invention is an improved method for measuring bone morphology and the like using an image of a bone to be examined on an X-ray film and an image of the bone to be examined by photon absorptiometory. An apparatus is provided.

[0002]

2. Description of the Related Art Various types of bone measurement such as confirmation of the state of growth and aging of human bones, or confirmation of the range of types of bone lesions such as osteoporosis and osteomalacia, the progress of the symptoms, and the effects of treatment. May be performed.

[0003] As a method of such bone measurement, X-rays are applied to a bone to be examined.
A so-called MD method ("Bone Metabolism", Vol. 13, pp. 187-195, in which the density of an image on the film is measured by a microdensitometer using an X-ray photographic film obtained by irradiation with X-rays and bone measurement is performed) 1980), "Bone Metabolism", Vol. 14, pp. 91-104 (1981), and the like, and photon-absorpsiometry for irradiating a test bone with gamma rays to measure the bone.

[0004] The MD method is easy to adopt in that it uses an X-ray film which can be easily obtained using an X-ray image photographing apparatus which is widely used as an apparatus for diagnosing fractures and the like, and is gradually becoming widespread. ing. It should be noted that it is difficult to say that gamma rays used in photon absorption symmetry are generally widely used in comparison with X-ray imaging apparatuses.

[0005] Conventional bone measurement by the MD method often involves manual operations as follows. That is, using a radiographic film obtained by irradiating the test bone with X-rays, first, for a bone image on the film, a reference point required for bone measurement by the MD method is manually determined. A part (for example, a part on the transverse line at the midpoint of the long axis of the second metacarpal bone) where bone measurement is to be performed in detail by a method determined using the points is selected. Then, while scanning the microdensitometer on the selected site, the intensity of the transmitted light obtained by irradiating the site with light is measured, and the intensity or absorbance of the transmitted light corresponding to the scanned site is measured. Is drawn on a predetermined chart paper. Further, the microdensitometer was scanned over the vertical line of the image of the aluminum stepped standard material (hereinafter referred to as the aluminum step) film radiographed together with the bone to be examined, and the intensity or absorbance of the obtained transmitted light was measured. The diagram is also described on the chart paper. Using the digitizer, the respective diagrams of the absorbance of the test bone and the absorbance of the aluminum step on the chart paper obtained as described above are input to a computer, and the absorbance of the test bone at each point is converted into the number of steps of the aluminum step. . Using the figures obtained by the conversion in this way, various indices representing the bone morphology at the target site are calculated in the computer, and the calculation results are output.

Recently, the inventors, including the present inventors, have detected the amount of transmitted light by using a CCD (charge coupled drive).
A bone measuring apparatus including an automatic reading means for an X-ray film image of a bone to be inspected, which employs a method of performing a bone measurement, has been proposed (see JP-A-2-220640).

In such a bone measuring apparatus, although it is possible to read an image of a bone to be inspected in each X-ray film and measure the bone based on the read data, the X-ray film is used.
How to place the bone to be examined when taking a radiograph (angle, movement)
In the case where is inappropriate, the measurement of the bone to be inspected may not be performed accurately as a result.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a method for measuring a characteristic of a bone based on an image to be examined when it is difficult to accurately measure the bone morphology due to an insufficient image or the like. It is an object of the present invention to provide a device that enables a measurement result of a value to be rationally grasped to be an abnormal value and enables more accurate bone morphology measurement.

The inventors of the present invention have conducted intensive studies in order to achieve such an object, and as a result, have prepared a criterion using characteristic values regarding a large number of images obtained over time for the same subject's same subject bone, It has been found that it is very effective to provide the bone measurement device with a function that can determine whether the characteristic value from the image of the same test bone newly input based on the determination criterion is normal or abnormal. Reached the present invention.

That is, the present invention comprises input means for inputting an image relating to a bone to be examined, measuring means for measuring characteristic values relating to the bone from the input image, and storage means for storing the characteristic values relating to the measured bone. In the bone measuring apparatus having the same, a determination criterion is determined by using a large number of determination criterion characteristic values measured by the measurement means from a large number of images previously input by the input means for the same test bone and stored by the storage means. A criterion creating means for calculating and storing;
The characteristic value measured from the newly input image for the same subject bone is evaluated using the criterion stored by the criterion creating means, whereby the characteristic value from the newly input image is evaluated. And a determination means for determining whether or not the method can be adopted.

According to the present invention, the criterion creating means updates a part of a criterion characteristic value used for calculating the criterion with a characteristic value measured from a newly input image. A bone measurement device including a means for updating characteristic values for use is included.

In the bone measuring apparatus of the present invention, the criterion calculated by the criterion creating means is an average value x and a standard deviation σ of the characteristic values from a large number of characteristic values for the criterion. And a bone measurement device for evaluating whether the evaluation of the new characteristic value by the determination means falls within the range of (the average value x) ± (the standard deviation σ). It is.

Hereinafter, the present invention will be described in more detail with reference to the drawings as necessary.

A feature of the apparatus of the present invention is that characteristic values are obtained from a large number of images inputted in advance for the same subject bone and stored as a group of characteristic values for determination criteria. Having a criterion creating means for obtaining a criterion, and evaluating a characteristic value obtained from a newly input image using the criterion, and determining that the characteristic value from the newly input image is appropriate. That is, there is provided a judging means for judging whether or not the object is an object.

As a specific example of the characteristic value for the judgment criterion relating to the bone to be examined, there is a bone length L and a bone width D when the bone to be examined is the second metacarpal bone (see FIG. 2 which will be described in detail later). ). As a specific example of a method of obtaining a criterion from a criterion characteristic value group including a large number of the characteristic values of the same subject bone, an average value Lx, Dx and a standard deviation Lσ, Dσ for each of L and D are: can give.

FIG. 1 is a schematic flow chart showing a specific example of a procedure for creating such a criterion. As shown in the figure, a method in which a part of the group of determination reference characteristic values is replaced with a characteristic value obtained from a newly input image and updated, for example, the image of the bone to be inspected changes over time. In the case where the bone to be examined changes over time, the criterion itself can be appropriately changed, which is advantageous. It should be noted that the update may be performed using only the ones that are determined to be appropriate according to the determination criteria.

As a specific example of the method of determination in the apparatus of the present invention, as shown in FIG. 2, a determination criterion including the average values Lx and Dx and the standard deviations Lσ and Dσ determined as described above is determined and newly determined. A characteristic value of an input image is evaluated and determined, and a result of the evaluation indicates whether the input image is appropriate or should be excluded. Note that the next step of measuring the characteristic value in FIG.
It indicates that it may be set in advance to select whether or not to make the determination referred to in the present invention,
What is necessary is just to provide it.

The number of data in the group of the criterion characteristic value is usually preferably 10 or more. Further, when inputting into the input means, for example, the ID No. of the bone to be inspected is used so that the identity of the bone to be inspected can be grasped. Is desirably input together with necessary data such as input timing.

Preferred examples of the test bone applicable to the apparatus of the present invention include cortical long bones such as the hand bone, the humerus, the radius bone, the ulna, the lazy bone, the tibia and the fibula. Further, other specific examples of the test bone applicable to the apparatus of the present invention include cancellous bone such as the calcaneus, the spine, and the end of the long bone.

A specific example of the input means for inputting an image relating to the bone to be examined in the apparatus of the present invention is a means for transmitting light to an X-ray film of the bone to be examined and detecting the amount of transmitted light. Can be Such input means include an image reading means in a so-called MD method using a microdensitometer, and a strip LED (light emitting diode).
ode) as a light source and an automatic image reading unit using a band-shaped CCD as a transmitted light amount detecting unit.

Another specific example of the means for inputting an image relating to the bone to be examined in the apparatus of the present invention is to irradiate the examination bone with gamma rays and detect the transmitted gamma dose by a detector. Image input means in so-called photon-absorpsiometry.

FIG. 3 shows a preferred embodiment of the bone measuring apparatus of the present invention. The automatic reading section 1 corresponds to the input means in the present invention.

That is, the automatic reading section 1 arranges licensors (CCDs) at right angles to the film moving direction, irradiates the film from the upper or lower surface of the X-ray photographic film with a band light source (LED), and illuminates the transmitted light. The light is condensed by a rod lens arranged to focus on the sensor, and a signal such as the intensity of transmitted light corresponding to the density of the X-ray film is obtained. At the same time, the light moves slightly in the direction perpendicular to the licensor and the band light source. And a microfilm running means using a pulse motor capable of driving.

In consideration of the case where the characteristics of the licensor, the belt-shaped light source, and the rod lens vary in the width direction, a DSP (Digital Signal) is used as a correction means.
Processor), REF (REF data storage unit) and A /
It has a D conversion unit. With this function, a change with time (deterioration of the belt-like light source, contamination of the rod lens, change in the sensitivity of the licensor) can be automatically corrected.

The film feed controller is control means for enabling detection of transmitted light by focusing on a specific portion of the X-ray film, and controlling the film to run intermittently at a predetermined speed. . The CCD driver has a function of controlling so that data stored in the CCD can be extracted at a predetermined timing. The LED controller is a light intensity adjusting means of the light source for adjusting the intensity of the light source in accordance with the density level of the X-ray film.

As a specific example of the measuring means in the bone measuring apparatus of the present invention, when the second metacarpal is a bone to be examined, FIG.
As shown in (1), there is a means for measuring characteristic values relating to a test bone, such as a bone length L and a bone width D.

FIG. 4 shows an example of the second metacarpal bone enlarged and displayed on the image display means of CRT in the bone measurement data processing section 2 in FIG. 30 is a display screen,
Reference numeral 31 denotes an image of the second metacarpal bone, and reference numerals 32, 33, and 34 indicate positions of reference points required for bone measurement. As the point input means, there are a cursor position display, an instruction control means, a light pen type input means, a method of externally inputting with a touch panel, and the like.

The data group read by the automatic reading unit 1 in FIG. 3 is stored by image storage means mainly comprising an image input / output unit and an image memory in the data processing unit 2. The data group relating to the stored image is a CRTC. The image is displayed as an enlarged image of the test bone as shown in FIG.

The bone length L and the bone width D can be calculated by obtaining an equal line between the input point, ie, the head 32 and the two points 33 and 34, and detecting the intersection. More specifically, FIG.
, The axis in the longitudinal direction of the second metacarpal is determined, and the distance between the two points 32 and 34 in a direction parallel to the axis is L, and (1/1 /
2) There is an example of a method for obtaining the bone width at the position L as D. As a specific example of such means, RO in FIG.
M (program storage unit for calculation) and RAM (portion for performing calculation and storing the result).

A specific example of the storage means of the group of the judgment reference characteristic values including the characteristic values according to the present invention is FDD in FIG. The MPU is a microprocessor that controls data fetching into an image memory, starting and stopping of a program, keyboard, CRT, and the like.

As a specific example of the criterion creating means and the deciding means, which are features of the present invention, first, a group of criterion values for criterion are read from the FDD, and Dx, Lx, D
σ and Lσ are calculated to create a judgment criterion, and then the new characteristic values D and L are Dx−Dσ <D <Dx + Dσ and Lx−Lσ
It is determined whether or not <L <Lx + Lσ. These are MP
It is realized by U, ROM, and RAM.

Further, the calculating means included in the bone measuring apparatus according to the present invention includes a predetermined position to be measured in the shadow image of the test bone stored in the shadow image storing means with reference to the reference point input by the point input means. May be determined as long as the calculation for the bone measurement can be performed using the stored data group relating to the image of the subject bone at the predetermined position. As an example, there is a microcomputer means comprising a ROM in which a calculation program for bone measurement is input and a RAM for calculation and temporary storage.

FIG. 5 shows, as a pattern, stored data on the transverse line of the midpoint of the long axis of the second metacarpal as shown in FIG. 4 in order to show a specific example of the contents of the calculation. is there. That is, D indicates the bone width, and the bone density distribution is represented by the shaded portion. d ₁ , d ₂
Indicates the width of the bone cortex, and d indicates the width of the bone marrow. GSmin corresponds to the minimum value of the valley 42 between the peak 40 and the peak 41, and indicates an index of the density of (bone cortex + bone marrow). GSmax1 and GSmax2 correspond to the maximum value of the peak portion, respectively. . ΣGS corresponds to the entire area of the hatched portion with respect to the width D (see “Bone Metabolism”, Vol. 4, pp. 319-325 (1981)).

Note that RS-232C and MODE shown in FIG.
M is for providing a communication function by being connected to a communication means when the bone measuring device is used for a bone evaluation system via the communication means, and PIO is for inputting / outputting digital control input / output to / from a computer system. It functions as an interface.

FIG. 6 shows the behavior of the time-dependent measurement results of the second metacarpal bone density ΔGS / D when abnormal data is excluded and when abnormal data is not excluded by the bone measuring apparatus of the present invention. The measurement result (lower column in FIG. 6) after eliminating the abnormal data for each of the characteristic values of the bone length L and the bone width D is lower than that in the case where the abnormal data is not excluded (the upper column in FIG. 6). It can be seen that a clear temporal behavior can be obtained.

[0036]

According to the bone measuring apparatus of the present invention, it is possible to automatically determine whether the input image of the test bone is normal or abnormal, so that the abnormal input can be automatically eliminated, and a more accurate image can be obtained. Easy to measure bone morphology.

[Brief description of the drawings]

FIG. 1 is a schematic flowchart illustrating an example of a criterion creating unit of a bone measurement device according to the present invention.

FIG. 2 is an example of a schematic flowchart in a determination unit of the bone measuring device of the present invention.

FIG. 3 is an example of a schematic block diagram of the entire bone measuring device of the present invention.

FIG. 4 is an example of an image of a test bone that can be applied to the apparatus of the present invention.

FIG. 5 shows an example of bone measurement in the device of the present invention.

FIG. 6 is an example in which a bone measurement result by the apparatus of the present invention is compared with a conventional bone measurement result.

Claims (3)

(57) [Claims] 1. A bone having input means for inputting an image related to a bone to be examined, measuring means for measuring a characteristic value related to the bone from the input image, and storage means for storing the measured characteristic value related to the bone. In the measurement device, a determination criterion is calculated using a large number of determination criterion characteristic values measured by the measurement means and stored by the storage means from a large number of images input in advance by the input means for the same test bone. A criterion creating means for storing, and evaluating the characteristic value measured from the newly input image for the same subject bone using the criterion stored by the criterion creating means. A determination unit configured to determine whether a characteristic value from a newly input image is an acceptable characteristic value. 2. The method according to claim 1, wherein the determination criterion creating means updates a part of the criterion characteristic value used for calculating the criterion with a characteristic value measured from a newly input image. The bone measuring apparatus according to claim 1, further comprising an updating unit. 3. The criterion calculated by the criterion creation means is an average value x and a standard deviation σ of the characteristic values from a large number of criterion characteristic values, and a new characteristic value 2. The bone measuring apparatus according to claim 1, wherein the evaluation is performed to determine whether a new characteristic value falls within a range of (the average value x) ± (the standard deviation σ).