WO1997008994A1

WO1997008994A1 - Bony tissue analyzer and method

Info

Publication number: WO1997008994A1
Application number: PCT/JP1996/002511
Authority: WO
Inventors: Akira Itabashi; Akira Takeuchi
Original assignee: Akira Itabashi; Akira Takeuchi
Priority date: 1995-09-07
Filing date: 1996-09-05
Publication date: 1997-03-13
Also published as: AU6889696A; JPH0970404A

Abstract

An apparatus for noninvasively analyzing the interior of a bony tissue with light and a method therefor. The apparatus is equipped with an operator (13), a sorter (14), and a display (15). The operator (13) calculates a light scattering coefficient νs' and a light absorption coefficient νa of a specimen (bony tissue) (6) based on the time-resolved waveform of the obtained transmitted light. The sorter (14) sorts the correlation between the coefficients νs' and νa thus obtained into any one of the first corrections where the values of both νs' and νa are high, the second correlation where the value of νs' is high while that of νa is low, the third correlation where the value of νs' is low while that of νa is high, and the fourth correlation where the values of both νs' and νa are low. The display (15) indicates the result of sorting.

Description

Description Bone tissue analyzer and method Technical field

The present invention relates to a bone tissue analysis device and method for examining bone tissue using laser light. Background art

Conventionally, to examine the inside of a bone, a method called the X-ray method that uses a simple X-ray to examine the structural change of the bone and a method that uses two types of X-rays to quantify calcium density in the bone have been used. Bone tissue has also been examined by a method called pQCT using high performance X-ray CT. At present, the results of bone density measurement by the DXA method and the pQCT method have been used as important indicators of bone strength. Recently, ultrasonic methods and the like have been studied as analysis methods that reflect not only bone density but also bone quality.

Bone tissue has a period of bone formation and resorption called remodeling, and measurement of this period is used, for example, to evaluate the progression rate of osteoporosis. Conventionally, the measurement of the cycle of bone formation and resorption is generally performed by histological examination using biopsy, or by a blood test or urine test. It is performed by measurement.

However, all of the above conventional bone tissue analysis methods using X-rays only estimate structural changes in bone from the distribution and density of calcium in bone. In addition, it is necessary to set up an exposure protection facility against X-ray exposure, and invasion of the subject by X-ray exposure is also a problem. In addition, the conventional bone tissue analysis method using the above-mentioned ultrasonic method can easily analyze and measure the physical strength (elastic strength) of the bone, but the bone strength obtained by the DXA method is measured. It only evaluates the correlation with the amount of salt (intraosseous calcium) and has a strong meaning as a simple bone mineral analyzer. That is, it is difficult to accurately and accurately analyze the inside of the bone tissue with this analysis method. In addition, regarding bioanalysis techniques for bone formation and resorption cycles, conventional biopsies are invasive and cannot be performed frequently. In addition, conventional analysis methods that measure bone formation and resorption markers by blood and urine tests do not directly measure bone tissue, and the results of the evaluation analysis are only indirect. Therefore, even with these analysis methods, it is difficult to accurately and accurately analyze the inside of bone tissue. Disclosure of the invention

The present invention has been made to solve such a problem, and a laser light source that emits laser light, a light guiding unit that guides the laser light emitted from the laser light source to a bone tissue, and a laser light that has passed through the bone tissue A light receiver that receives light, a calculator that calculates the light scattering coefficient and light absorption coefficient of bone tissue from the obtained transmitted light, and the relative relationship between the calculated light scattering coefficient and light absorption coefficient is expressed by the value of each coefficient. Are high both, the first relative relationship, the light scattering coefficient value is high, the light absorption coefficient value is low, the second relative relationship, the light scattering coefficient value is low, and the light absorption coefficient value is high. The bone tissue analyzer was provided with a classifier for classifying into any of the fourth relative relationships having low values, and a display for displaying the classification result.

A first step of irradiating the bone tissue with laser light emitted from the laser light source; a second step of receiving light transmitted through the bone tissue; and a light scattering coefficient of the bone tissue based on the obtained transmitted light. The third step of determining the light absorption coefficient and the relative relationship between the determined light scattering coefficient and the determined light absorption coefficient are described in the first step where the values of the coefficients are both high. The second relative relationship where the light scattering coefficient value is high and the light absorption coefficient value is low, the third relative relationship where the light scattering coefficient value is low and the light absorption coefficient value is high, or the fourth relative relationship where the value of each coefficient is low. And a fourth step for classifying the bone tissue into any one of the relative relationships.

When the relative relationship between the obtained light scattering coefficient and light absorption coefficient is classified into the first relative relationship, the amount of bone mineral, which is a light scatterer contained in the bone, is high, and the light absorption in the cavity of the bone is high. It is analyzed that the body contains many blood components. Also, when classified into the second relative relationship, it is analyzed that the bone mineral content is not high, and that the cavity contains a large amount of fat, which is a light scatterer, instead of blood components. In addition, when classified into the third relative relationship, it is analyzed that bone mineral content is low, the cavity is formed large, and a large amount of blood components is contained in the cavity. When classified into the fourth relative relationship, it is analyzed that bone mineral content is low and that the blood cavity and the fat content are little contained in the cavity. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram showing a bone tissue analyzing apparatus according to one embodiment of the present invention, and FIG. 2 is a time-resolved measurement of each bovine tissue measured using the bone tissue analyzing apparatus according to this embodiment. Fig. 3 is a graph showing the measured waveforms. Fig. 3 shows the maximum light intensity and peak time of the time-resolved measured waveform of the human lumbar vertebrae block measured using the bone tissue analyzer according to the present embodiment, and the BMD. FIG. 4 is a graph showing the correlation between the BMD value and the average optical density obtained by irradiating the continuous light to the bovine bone tissue and FIG. FIG. 5 is a graph showing a time-resolved measurement waveform of the heel of a living human measured using the bone tissue analyzer according to the present embodiment. Schematic diagrams of attenuation due to light absorption and each It is a figure showing a time-resolved waveform of transmitted light. BEST MODE FOR CARRYING OUT THE INVENTION

Next, a bone tissue analyzing apparatus and method according to an embodiment of the present invention will be described.

FIG. 1 is a block diagram showing a schematic configuration of the bone tissue analyzer according to the present embodiment.

Titanium 'Sapphire' pulsed laser light source 1 has a light intensity of about 400 mW, a beam diameter of 2 mm, a wavelength of 750 to 800 nm, and a half width of 100 fs at a repetition frequency of 76 MHz. Out of the laser beam. This pulsed laser light is guided to the sample 5 by the optical mirrors 2, 3, and 4 constituting the light guiding means. Sample 5 is a specimen 6 such as a bone tissue or the like formed in a block shape of 10 mm square, and is fixed to a box-shaped black acryl senor 8 filled with saline (physiological saline) 7. The pulsed laser light enters from the center of the transparent glass window provided in a part of the black acrylic sensor 8 and is radiated toward the specimen 6. The light transmitted through the sample 6 exits from the transparent glass window provided opposite the entrance window, and is received by the receiver (model name M2816, manufactured by Hamamatsu Photonics) 9 installed immediately after. Is detected. The transmitted light detected by the receiver 9 is integrated 10 times at 2 MHz by an optical oscilloscope (model O〇S—01, manufactured by Hamamatsu Photonics) 10. Then, in this optical oscilloscope 10, based on the integrated output of the light receiver 9, the time that the transmitted light travels from the light incident point of the sample 6 to the light detection point and the intensity of the transmitted light are time-resolved. It is measured. This measurement result is recorded on the optical oscilloscope 10 as a time-resolved measurement waveform. In addition, the light emitted from the laser light source 1 and detected by the optical receiver 12 similar to the optical receiver 9 via the optical mirrors 12 and 11 is input to the optical oscilloscope 10 as reference light. ing. The arithmetic unit 13 obtains the light scattering coefficient μ s ′ and the light absorption coefficient μ a of the sample 6 from the obtained time-resolved measurement waveform of the transmitted light. Common methods for evaluating these coefficients include methods that evaluate both coefficients analytically from the light diffusion equation and those that use a computer-based stochastic method called the Monte Carlo method to measure the scattering and absorption of light numerically. There is a method to simulate and evaluate it. The classifier 14 classifies the relative relationship between the light scattering coefficient μ s ′ and the light absorption coefficient / ia obtained by the arithmetic unit 13 into one of the following four relative relationships. In other words, the first relative relationship where the value of each coefficient μ s ′ / a is high, the second relative relationship where the value of the light scattering coefficient / / s ′ is high and the value of the light absorption coefficient μ a is low, The third relative relationship where the value of the coefficient μs' is low and the value of the light absorption coefficient μa is high, or each coefficient μs

Classify into any of the fourth relative relationships where both values of Ha are low. The display 15 displays the classification result.

FIG. 2 is a graph showing the results of time-resolved measurement of each bovine tissue using the above-mentioned bone tissue analyzer. In this measurement, the wavelength of the pulsed laser light was set at 805 nm. The vertical axis of the graph indicates the relative intensity of transmitted light (INTENS ITY), and the unit is the photon amount [COUNTS]. In addition, the horizontal axis of the graph indicates the elapsed time (T IME) since the pulse laser beam hit the specimen 6, and the unit is [PS:]. For sample 6, bovine muscle, fat, trabecular bone and cortical bone were each formed into a 10 mm square block. In the Dalaf, waveform A is a time-resolved measurement waveform of a raw eclipse without light scattering and absorption, and is used as a reference waveform. Waveforms B, C, D, and E are time-resolved measurement waveforms of muscle, fat, cancellous bone, and cortical bone, respectively. In general, when the specimen 6 is a tissue that has strong optical absorption, the maximum light intensity (IM ax entity, IM ax) decreases as the transmitted light decreases, and the time-resolved measurement waveform becomes The peak time to reach the peak (peak time, PT) shifts forward, that is, to the left of the graph. If the sample 6 is a tissue with strong light scattering, The peak intensity of the time-resolved measurement waveform shifts backward, that is, to the right of the graph, although the intensity with respect to the intensity also decreases.

In the waveform B of the muscle, the maximum light intensity is high, and the peak time is delayed only by about 50 [PS] compared to the peak time of the reference waveform A of the raw food. This is because the muscle has good light transmission and low scattering, even though the muscle contains myoglobin, which has an absorption spectrum in the wavelength region of the irradiated light. Is shown. In the case of cancellous bone waveform C, the maximum light intensity is high and transmissive, but the scattering is much higher than that of muscle. The peak time of the same waveform is after 100 [PS], and a photon with a long optical path length that has been greatly scattered can be detected near 400 [PS]. Also, fat waveform D shows that fat tissue is a strong light scatterer. In addition, waveform E of cortical bone shows a stronger light scattering pattern.

Using the bone analyzer described above, a 10 mm square block of trabecular bone was formed from the central part of the third lumbar vertebra of the human (human) obtained at the time of the autopsy of three cases. Time-resolved measurement was performed. This human lumbar spine sample was measured before and after ultrasonic cleaning for 40 minutes to consider the effect of hemoglobin (Hb) contained in Sample II.

Figure 3 is a graph showing the measurement results. The graph in the same figure (a) shows the correlation between the bone density BMD of the human lumbar vertebra and the maximum light intensity IM aX of the time-resolved measurement waveform. The vertical axis of the graph is BMD [g / cm2], The horizontal axis is I Max [counts]. In addition, the graph in Fig. 3 (b) is a graph showing the correlation between the bone density BMD of the human lumbar vertebra and the peak time PT of the time-resolved measurement waveform, and the vertical axis of the graph is BMD [g / cm2], horizontal. The axis is PT [ps]. Here, the BMD value was measured using a DXA method measuring instrument (model name: DPX-L, manufactured by Luna, USA), and the high resolution mode (High resolution) of small animal software was used. mode). Also, this In each of these graphs, the straight line a obtained from the black circle is the result obtained by measuring the sample before washing, and the straight line b obtained from the white circle is the sample obtained by ultrasonic cleaning. It is a result obtained by measuring later. Plot H1 in each of these graphs is lumbar spine sample data of a 50-year-old man who died of alcoholic liver failure. Plot H2 is sample data from a 54-year-old woman who died of ovarian cancer. Plot H3 is a sample of a lumbar spine sample from a 63-year-old man who died of hepatocyte cancer.

It can be seen from the graph (a) that the sample having a low BMD is easy to transmit light. Also, from the graph of FIG. 11B, the value of PT indicating the increase in scattering tended to increase as the value of BMD increased. In addition, such a relative relationship between the sample measurement results was maintained even when Hb was removed by ultrasonic cleaning, but after removal, IMaX increased as a whole as shown in the figure, and PT increased. Shifted forward.

The relative relationship between BD and IMaX can also be confirmed by irradiating the sample with continuous light. This has been confirmed by the following experiment. In other words, a halogen lamp is used as the light source, and the output of this light source is reduced to about 200 [W] by the dimmer. The continuous diffused light obtained in this way is applied to a bone sample fixed between 2 mm thick white acrylic plates. The light transmitted through the bone sample was received by a computer-type CCD scanner (model name EPS0N6500ART, manufactured by Seiko Epson Corporation), and the obtained image data was analyzed by a computer. That is, the obtained RGB image data was converted to grayscale image data (gray scale) of 256 gradations, and the average optical density was calculated from the converted data. As a measurement sample in this experiment, a 10 mm square bone block taken from the trabecular bone of the proximal end of a bovine femur was used. Factors affecting the amount of light transmitted through the sample are limited to the scattering attenuation by calcium. For this purpose, this sample was gradually decalcified in a 15% EDTA 2 Na solution adjusted to pH 7.2, and the crystal of Ca in the bone block (hydraoxyapatite) was maintained without changing the bone structure. G) was changed only. The BMD in the bone samples was measured on the second, ninth, eighteenth, and thirty days after decalcification was started by the above method.

The RGB image obtained by this measurement became brighter as the decalcification proceeded. The relationship between the average optical density (mean density) obtained by analyzing the grayscale image data and the BMD value measured by the DXA method described above is shown in the graph of Fig. 4. . The vertical axis of the graph is the average optical density, and the horizontal axis is BMD [g / cm2]. The graph confirms that the average optical density decreases with decreasing BMD, and that the amount of light transmitted through the bone sample increases linearly with decreasing BMD value, and the correlation function R 2 is 0.99. It was as high as 6. In other words, the experimental results are consistent with the time-resolved measurement results using pulsed laser light shown in Fig. 3 (a).

From the experimental results, it can be seen that the change in the amount of transmitted light when only the content of the hydroxyapatite, which is a light scatterer, was changed was due to the change in the scattering characteristics, that is, the scattering was manipulated and attenuated before reaching the light receiving part. It was found that it can be evaluated as an increase or decrease in the number of fonts. These results revealed that there is a strong correlation between light scattering characteristics and BMD, suggesting that bone mineral density can be measured by light. In addition, by evaluating the waveform obtained by the time-resolved measurement method using pulsed laser light in the near infrared region, which has better tissue permeability than visible light, it is possible to separate and evaluate the scattering and absorption characteristics of tissue. Furthermore, it was suggested that intraosseous components such as Hb and fat could be measured as optical changes. These results also show that the absorption attenuation of X-rays and the attenuation of light scattering by calcium show the same tendency, and the amount of bone mineral, which is currently measured mainly by X-rays, is measured by light scattering. By It was also found that it was also possible to weigh.

Instead of the optical oscilloscope shown in Fig. 1, a titanium channel sapphire (model C4332, manufactured by Hamamatsu Photonics) with more sensitivity was used. Pulsed laser light in the near-infrared region with a wavelength of 754 nm emitted from pulsed laser light source 1 was irradiated from the inside of the heel (about 45 mm thick) of the human. The results shown were obtained. Here, the time-resolved measurement was performed such that the pulsed laser light was integrated 200 times and light irradiation was performed for about 1 minute so that a sufficient signal intensity was obtained. The graph in (a) shows the time-resolved measurement result of the reference light, and the graph in (b) shows the time-resolved measurement result of the signal light. In each of these graphs, the horizontal axis is the time [ns] since the light hits the specimen, and the vertical axis is the number of photon counts representing the light intensity of the transmitted light. The diagonal axis to the right indicates the detection channel of the streak camera. From the graph shown in ( _a ) of the same figure, the reference light of the raw edible is observed at a peak time of about 400 [ps]. Also, from the graph shown in the same figure (b), the initial photon that passed through the heel of about 45 [mm] thickness appeared about 500 [ps] later than the reference waveform of saline. However, the peak time was delayed by 1500 [ps]. Considering that light travels at a speed of about 0.23 [mm / ps] in the biological tissue 內, the peak position near 150 [ps] in the measured waveform is 4.5 cm thick. This means that the photon scattered 40 [cm] through the heel. The results also revealed that information on such remarkable light scattering of living organisms can be obtained non-invasively.

X-rays and light are the same electromagnetic wave, but their properties are different due to their different wavelengths. When bone tissue is measured using electromagnetic waves in the X-ray wavelength range (several nm), the photon is absorbed by Ca in the bone tissue. Also, when measuring bone tissue with electromagnetic waves in the wavelength range of light, it is necessary to use It is known that remarkable light diffusion occurs due to a change in the refractive index due to a change in the shape of a tissue or bone tissue. Thus, while both X-rays and light are electromagnetic waves, the absorption attenuation of X-rays in bone tissue and the absorption and scattering attenuation of light in bone tissue have been clarified by the above-mentioned measurement using continuous light. The same tendency was shown. Therefore, when analyzing bone tissue using light, the same attenuation of light is observed whether the target is a dispersive substance or an absorbent substance. Even when measuring with light, it is not possible to distinguish between the power of attenuation of light due to scattering or the attenuation of light due to absorption.

This problem can be solved by using photometry based on time-resolved measurement. In other words, the specimen is irradiated with ultra-short pulsed light, and changes in the movement process that occur when the incident photons pass through the specimen while being scattered or absorbed, that is, changes in the optical path length, are received. By plotting the photons on the time axis, time-resolved measurement can be performed, and the light absorption and scattering characteristics can be accurately evaluated. That is, by measuring how many seconds the photon whose incident time and position are known reaches the light receiver, the optical path length of the scattered photon can be estimated. This makes it possible to distinguish between scattering and absorption factors.

Fig. 6 (a) shows the optical path length when light is applied to the specimen (bone tissue) 6 where the light absorber 21 is present, and Fig. 6 (b) shows the light scatterer 22. The optical path length when the existing specimen (bone tissue) 6 is irradiated with light is shown. When the light absorber 21 is present in the sample 6 as shown in (a), the time-resolved measurement waveform is the graph in FIG. (C), and the light scatterer 22 is in the sample 6 In the case of (b), the time-resolved measurement waveform is shown in the graph of (d). The horizontal axis of each graph is time [ps], and the vertical axis is the number of photons. In the typical light absorption pattern shown in Fig. (C), Although the peak time of the signal waveform 23 is slightly delayed from the peak time of the reference light waveform 24, in the typical light scattering pattern shown in FIG. 11D, the peak time of the signal waveform 25 is the same as that of the reference light waveform. It is significantly behind the peak time of 26. The maximum light intensity of the signal waveform 23 is larger than the maximum light intensity of the signal waveform 25.

The parameters obtained by evaluating the waveform measured by light are basically two parameters: equivalent scattering coefficient / s' and absorption coefficient μa. These coefficients are obtained by the calculator 13 of the bone tissue analyzer shown in FIG. 1 described above, and the state of the bone tissue is classified by the classifier 14 based on the obtained coefficients as described above. It becomes possible to do various state analysis of. For example, the following analysis can be performed by applying the bone tissue analyzer according to the present embodiment to the heel of a living human.

That is, if the calculated relative values of the light scattering coefficient μ s ′ and the light absorption coefficient / a are classified into the first relative relationship where both the values of the respective coefficients / is ′ and a are high, they are included in the bone. The amount of bone mineral, which is a light scatterer, is high, and the intertrabecular space (cortical bone marrow cavity) is considered to contain a large amount of bone marrow tissue rich in blood components, which are light absorbers. Therefore, the bone tissue classified into the first relative relationship can be analyzed as healthy bone tissue.

In addition, when the value of the light scattering coefficient / X s' is high and the value of the light absorption coefficient μa is low, the bone mineral content is not high, and the intratrabecular space (bone marrow cavity) is not high. The bone marrow tissue, which is rich in blood components, is analyzed to have been replaced by fat tissue, which is a light scatterer. Therefore, it can be analyzed that this bone tissue with an increased fat content has undergone bone changes typified by old age, in which the cycle of bone formation and resorption is slow.

When the light scattering coefficient μ s ′ is low and the light absorption coefficient μ a is high, the bone mineral content is low and the trabecular width is narrow. It is analyzed that the intertrabecular space is large and that the cavity contains a large amount of bone marrow tissue rich in blood components. Therefore, this bone tissue, which is rich in blood components, can be analyzed as having bone changes represented by postmenopausal osteoporosis in women who have a rapid cycle of bone formation and resorption.

In addition, when the values of the coefficients μ s ′ and a are both low, the bone mineral content is low, and the blood component and fat content in the intertrabecular space (bone marrow cavity) are small. Is analyzed to be included. Therefore, this classification is difficult to classify pathologically, such as thin (small) bones and atrophied bones, but it is regarded as a hated type of the type classified in the second relative relationship above. be able to. Bone tissue can be analyzed to have bone changes that are likely to be common in old age.

Here, the evaluation of whether each coefficient value is high or low is based on the average value obtained by statistically processing the coefficient values of normal persons with various foot thicknesses and various skin colors. It is possible to do it.

Initially, osteoporotic bone lesions change from cortical bone in the diaphysis to trabecular bone such as the lumbar spine, femoral neck, and calcaneus. With osteoporosis, bone mineral density in the trabecular bone decreases, and as a result, the trabecular width narrows and the intertrabecular space

The (bone marrow cavity) presents a structural change that increases. In women, osteoporosis is clinically classified as occurring several years after menopause or as occurring in old age. The former is a condition in which bone lesions progress rapidly due to the activation of bone resorption due to the rapid deficiency of female hormones during the earlier period of bone formation and resorption. In the latter, the pathology is mainly due to a decrease in bone formation, but the disease progresses gradually due to the slow cycle of bone formation and resorption. Naturally, the two are different in the optimal treatment and the time to start the treatment is also different, so it is very important to distinguish them.

A type that has a fast cycle of bone formation and resorption as in postmenopausal osteoporosis In cancellous bone tissue, the intertrabecular space is filled with blood-rich bone marrow tissue. In addition, it is presumed that blood components are replaced by adipose tissue in the bone marrow tissue of the intertrabecular space of the cancellous bone tissue, which has a slow cycle of bone formation and resorption, as represented by old age. Mild changes were also observed in the cortical bone, and in severely advanced osteoporosis, the thickness of the cortical bone decreased, resulting in a decrease in the amount of bone mineral in the cortical bone and the fat in the medullary cavity. Is recognized.

On the other hand, light is different from X-rays and ultrasound, and has a strong scattering property for intraosseous calcium, and near-infrared light is directed to Hb in the bone marrow cavity (intertrabecular space in cancellous bone). Indicates absorption characteristics. In addition, light mainly exhibits scattering characteristics with respect to adipose tissue. Therefore, if the scattering is very strong in the measurement results, two types of evaluation can be considered as to whether the bone tissue has a high calcium content, a complicated internal structure of the bone, or a high fat content. Can be Discrimination of these evaluations can be performed by evaluating the absorption characteristics of Hb as described above. If the bone tissue shows strong light absorption properties, it can be assumed that the bone is rich in blood components of bone marrow and is a healthy bone tissue with a high BMD. Also, if the absorption characteristics are weak, it is possible that blood is replaced by fat inside the bone marrow, and it is speculated that the increase in scattering in this case is not due to the effect of high BMD but to an increase in fat mass. be able to. In addition, by examining light with a wavelength around 930 [nm], which has the peak of the fat absorption spectrum, it is possible to measure fat more clearly. If the scattering is weak, the BMD is suspected to be low.However, if the trabecular gap is widened due to osteoporosis and contains a lot of blood, the absorption becomes even stronger. .

Although the measurement was not performed by the apparatus used in this example in this example, the absorption spectrum of co-gen also exists in a higher wavelength range, so that by using a laser photometering system that can measure in a wider range of wavelengths, , Scattering of bone tissue, It is possible to make a new assessment of bone quality by measuring absorption characteristics and spectroscopic analysis using absorption spectra.

This example demonstrates that time-resolved measurement is also performed on human bone tissue in a living state. Further, when interpreting the time-resolved measurement waveform, the light scattering coefficient and light absorption coefficient of the bone tissue are determined. By classifying these coefficients as described above according to the value of, it became possible to take into account the effects of bone surrounding tissue. It is a very difficult problem to estimate the change in the photon's movement path when light passes through the peri-bone tissue where the skin, adipose tissue, muscular tissue, tendon tissue, etc. are complexly overlapped. In recent years, the effects of the optical path length when transmitting through multiple tissues with different scattering and absorption coefficients have been mathematically studied by various model experiments, but a final solution to this problem has been obtained. Absent. There have been few reports of optical studies of bone tissue, and there is only a study of the basic optical properties of thin slices of pig skull using continuous light. There has been no example in the world of analyzing bone tissue from the viewpoint as in this example, and this report seems to be the first one. By analyzing the bone tissue using the bone tissue analysis apparatus and method according to the present embodiment, the above-described bone change accompanying osteoporosis can be analyzed with high accuracy.

In the description of the above embodiment, the pulse laser system was used to irradiate the pulsed laser beam to the bone tissue, and the light scattering coefficient and the light absorption coefficient in the bone tissue were obtained by the time-resolved measurement method. However, it is also possible to employ a fuse modulation method in which bone tissue is irradiated with continuous laser light to obtain each of these coefficients. In this case, modulation is applied to the continuous laser light that irradiates the bone tissue, and time information such as how the phase of the modulated light changes by transmitting through the bone tissue is examined. The light scattering coefficient and light absorption coefficient of the bone tissue are determined. Use continuous laser light as the light source This system is simpler to handle than a system using a pulse laser beam in terms of cooling, stability and maintenance of the light source, and can be obtained at a low price. Therefore, if the device is configured using such a light source, it becomes possible to analyze the bone tissue more easily. Industrial applicability

As described above, according to the present invention, by analyzing the relative relationship between the light scattering coefficient and the light absorption coefficient in the bone tissue obtained from the transmitted light, the bone tissue 內 can be non-invasively analyzed by light. It becomes possible to do. For this reason, the conventional bone tissue analysis method using X-rays only estimates the structural change of the bone from the distribution and density of calcium in the bone, but according to the present invention, the measured scattering coefficient and It is possible to more specifically evaluate the inside of bone tissue based on the absorption coefficient, and it becomes possible to analyze changes in bone structure with higher precision and accuracy. Therefore, superior analysis can be performed compared to conventional bone tissue analysis methods using ultrasonic methods and indirect conventional analysis methods that measure bone formation and resorption markers using blood and urine tests. It becomes possible to do. In addition, since measurement is performed using light, there is no need for an exposure protection facility for X-ray exposure, and there is no need to worry about the effects of invasion on the subject.

Claims

Range of request

1. A laser light source that emits laser light, a light guide that guides the laser light emitted from the laser light source to bone tissue, a light receiver that receives light transmitted through the bone tissue, and the obtained transmitted light. A calculator for calculating the light scattering coefficient and the light absorption coefficient of the bone tissue, and the first relation, where the values of the coefficients are both high, and the light scattering coefficient value Classified as either a second relative relationship with a high light absorption coefficient value and a low relative value, a third relative relationship with a low light scattering coefficient value and a high light absorption coefficient value, or a fourth relative relationship with both low coefficient values A bone tissue analyzer, comprising: a classifier; and a display for displaying the classification result.

2. The laser light source emits a pulsed laser beam, and the arithmetic unit calculates the time required for the transmitted light to travel from the light incident point to the light detection point of the bone tissue and the time-resolved measurement result of the transmitted light intensity. 2. The bone tissue analyzer according to claim 1, wherein the light scattering coefficient and the light absorption coefficient are obtained.

3. The laser light source modulates and emits continuous laser light, and the calculator determines that the light scattering coefficient and the light absorption coefficient are based on the phase change of the modulated light of the continuous laser light transmitted through the bone tissue. The bone tissue analysis device according to claim 1, wherein

4. The bone tissue analyzer according to claim 1, wherein the evaluation of whether each of the coefficient values is high or low is performed based on an average value of each of the coefficient values of a normal person.

5. The first step of irradiating the bone tissue with the laser light emitted from the laser light source, the second step of receiving the light transmitted through the bone tissue, and the light scattering coefficient of the bone tissue from the obtained transmitted light. The third step of obtaining the light absorption coefficient and the relative relationship between the obtained light scattering coefficient and the light absorption coefficient are described by the first phase in which the values of each coefficient are both high. Pair relation, second relative relation with high light scattering coefficient value and low light absorption coefficient value, third relative relation with low light scattering coefficient value and high light absorption coefficient value, or fourth relation with low coefficient values And a fourth step of categorizing the bone tissue into any one of the relative relationships described above.

6. The laser light source in the first step emits a pulsed laser beam, and the calculation of the light scattering coefficient and the light absorption coefficient in the third step is performed from the light incident point of the bone tissue to the light detection point. 6. The bone tissue analysis method according to claim 5, wherein the method is performed based on a time elapsed through the transmitted light and a time-resolved measurement result of the intensity of the transmitted light.

7. The laser light source in the first step modulates and emits a continuous laser beam, and the calculation of the light scattering coefficient and the light absorption coefficient in the third step is performed by calculating the continuous laser light transmitted through a bone tissue. 6. The bone tissue analysis method according to claim 5, wherein the method is performed based on a phase change of the modulated light.

8. The bone according to claim 5, wherein the evaluation of whether each of the coefficient values is high or low in the fourth step is performed based on an average value of each of the coefficient values of a normal person. Tissue analysis method.