JP2638875B2 - Bone mineral quantitative analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to an apparatus for quantifying calcium contained in human bone.

[Prior art]

By measuring the density of bone, bone mineral can be quantified. Measuring bone density requires the use of two different energies of radiation to collect their transmission data. Conventionally, X-rays emitted from an X-ray tube are reflected on a crystal lattice to produce monochromatic X-rays, which are transmitted through a human body to obtain data. As shown in FIG. 5, an X-ray radiated from the X-ray tube 1 is incident on a crystal lattice 2 having a lattice constant d at an incident angle θ. Then, only X-rays of wavelength λ satisfying the condition of 2d sin θ = λ are reflected. X-rays of this specific wavelength are applied to the patient 4 via the collimator 3 and the transmitted X-rays are incident on an X-ray position detector (such as a gamma camera) 5 to obtain transmitted X-ray data. Then, the X-ray beam is scanned so as to cross the patient 4 to obtain transmission data. Since it is necessary to obtain the transmitted X-ray data by changing the energy, the crystal lattice 2 is rotated by an appropriate mechanism and scanned again to obtain the data.

[Problems to be solved by the invention]

However, conventionally, it is necessary to perform two scans with X-ray beams having different energies.
There is a problem that an inspection time is required. It is an object of the present invention to provide a bone mineral quantitative analyzer that can reduce the examination time.

[Means for solving the problems]

A bone mineral quantitative analyzer according to a first aspect of the present invention for solving the above problems includes a means for generating radiation, a single crystal lattice irradiated with the radiation, and a radiation reflected by the crystal lattice. Means for collimating only those having predetermined two reflection angles and simultaneously irradiating the object with radiation of two different energies, and radiation detecting means for transmitting these two energies of radiation through the object and A wave height analyzing means for analyzing the wave height of the output of the radiation detecting means to separate transmission data relating to radiation of each energy, and a means for calculating the bone density by arithmetically processing the separated data. In addition, a bone mineral quantitative analyzer according to a second aspect of the present invention for solving the above-mentioned problems includes a means for generating radiation, two crystal lattices each of which is irradiated with the radiation, and these two crystal lattices. Means for simultaneously irradiating the subject with two different energies by collimating the radiation reflected at a specific angle, and radiation detecting means for transmitting these two energies through the subject. A wave height analyzing means for analyzing the wave height of the output of the radiation detecting means to separate transmission data relating to radiation of each energy, and a means for calculating the bone density by arithmetically processing the separated data.

[Action]

In the bone mineral quantitative analyzer according to the first aspect of the invention, when the radiation emitted from one radiation generating means is applied to one crystal lattice, if the incident position on the crystal lattice is different, the radiation is incident and reflected at different angles. The energy of the reflected radiation will be different. Therefore, if the radiation incident and reflected at two different angles is collimated, the two radiations obtained by the collimation have energies corresponding to those angles, respectively.
Therefore, the subject can be simultaneously irradiated with the two radiations having different energies. When the radiation transmitted through the subject is detected, the wave height of the detection output varies depending on the energy. Therefore, the peak height analysis of the detection output is performed, and the transmission data regarding the radiation of each energy is separated. Then, the transmission data for these two energies is arithmetically processed, and the bone density (mass per unit area of the bone) is calculated. As described above, since the transmission data relating to radiation of each energy is separated by the peak analysis of the detection output, the configuration is simple and the influence of noise or the like can be removed. In the bone mineral quantitative analyzer according to the second aspect of the present invention, two crystal lattices are irradiated with radiation and the radiation reflected at a specific angle determined by the lattice constant is collimated to emit radiation of two different wavelengths. Can be obtained at the same time. Therefore, also in the case of the second invention, similarly to the first invention, the subject can be irradiated with radiations of two different energies simultaneously with a simple configuration and without being affected by noise or the like. Bone density can be obtained by simultaneously obtaining transmission data of energy by radiation.

【Example】

In one embodiment of the present invention, as shown in FIG. 1, an X-ray generated from an X-ray tube 1 is applied to a crystal lattice 2. Then, the X-rays are reflected by the crystal lattice 2, and a collimator 3 having two slits is arranged on the reflection side. The collimator 3 is attached so as to maintain a fixed positional relationship with the crystal lattice 2. Therefore, X-rays incident on the crystal lattice 2 at the incident angles θ1 and θ2 and reflected at the angles θ1 and θ2 are taken out from the slits of the collimator 3 and radiated to the patient 4 as thin beams. . Therefore, these X-ray beams become monochromatic X-rays having energies E1 and E2 corresponding to the angles θ1 and θ2. The X-ray beam transmitted through the patient 4 is incident on an X-ray position detector 5 such as an X-ray TV camera or a gamma camera. This X
The output signal of the line position detector 5 is sent to a wave height analyzer 6 where it is subjected to energy discrimination, and signals corresponding to the energies E1 and E2 are extracted. The obtained data is sent to the data processing device 7, where the data processing described later is performed. The scan motor 8 includes an X-ray tube 1, a crystal lattice 2 and a collimator 3 integrated with each other, or only the crystal lattice 2 and a collimator 3 integrated with an arrow around a suitable rotation center 81 (perpendicular to the paper). Rotate as A. In this way, the X-ray beams of two energies are simultaneously scanned with respect to the patient 4, and the X-ray transmission data of two energies are obtained at the same time. FIG. 2 shows a second embodiment. In the second embodiment, as shown in FIG. 2, X-rays generated from the X-ray tube 1 are incident on two crystal lattices 21 and 22 set at different angles. The angle θ of those reflected X-rays
The collimator 3 is provided so that only the light reflected at 1, θ2 is taken out through the slit. Therefore, two X-ray beams emitted from the two slits toward the patient 4 have energies E corresponding to angles θ1 and θ2.
It becomes a monochromatic X-ray of 1, E2. The X-ray beam transmitted through the patient 4 is incident on an X-ray position detector 5 such as an X-ray TV camera or a gamma camera, and the output signal of the X-ray position detector 5 is sent to a pulse height analyzer 6 for energy discrimination, Energy E1, E2 above
Are extracted. The obtained data is sent to the data processing device 7, where the data processing described later is performed. The scan motor 8 linearly moves the X-ray tube 1, the crystal lattice 2, and the collimator 3 integrally as shown by the arrow B. Thus, the X-ray beams of two energies are simultaneously scanned in parallel to the patient 4, and the X-ray transmission data of two energies are obtained at the same time. It should be noted that scanning may be performed by rotating as in the first embodiment (in the case of the first embodiment, scanning may be performed by linearly moving as in the second embodiment). Also, instead of setting the crystal lattices 21 and 22 at different angles, two crystal lattices having different lattice constants may be arranged at the same angle. The mass absorption coefficient and density of the soft tissue 41 of the patient 4, as shown in FIG. 3 and μ _s / ρ _s, M _s respectively, and each of the mass absorption coefficient and density of the bone _{42 μ b / ρ b, M} b, Assuming that the X-rays incident at the intensity I ₀ pass through the patient 4 and become the intensity I, the following equation holds for the X-rays of two energies E1 and E2. I ₁ = I ₀₁ exp [− [｛μ _b (ε ₁ ) / ρ _b ｝ · M _b + ｛μ _s (ε ₁ ) / ρ _s ｝ · M _s ]] I ₂ = I ₀₂ exp [− [｛ μ _b (ε ₂ ) / ρ _b ｝ · M _b + ｛ _μs (ε ₂ ) / ρ _s ｝ · M _s ]] From these equations, M _b = [RST · ｛1n (I ₁ / I ₀₁ ) ｝｝ − 1n (I ₂ / I ₀₂ )] / [μ _b (ε ₂ ) / ρ _b −RST · ｛μ _b (ε ₁ ) /
ρ _b ｝], the bone density M _b can be obtained. Where μ _b / ρ _b
Is an experimental value, and RST is given by the following equation. _{RST = {μ s (ε 2} ) / ρ s} / {μ s (ε 1) /
ρ _s ｝ Therefore, this RST is obtained as follows while transmitting the X-ray only to the soft tissue 41 of the patient 4 as shown in FIG. _{I '1s = I 1 sexp [} - {μ s (ε 1) / ρ s} · M s] I' 2s = I 2 sexp [- {μ s (ε 2) / ρ s} · M s] RST = 1n ( _I'2s / _I2s ) / 1n ( _I'1s / _I1s ) These operations are performed by the data processor 7.

【The invention's effect】

According to the bone mineral quantitative analyzer of the present invention, two energy monochromatic X-ray scans can be performed at the same time, data for two energies can be collected by one scan, and bone density can be calculated from this. In addition, the examination time until the calculation of bone density can be greatly reduced. In addition, since the separation of the data for the two energies is performed by the wave height analysis of the detection output, the configuration is simple and is not affected by noise or the like.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a first embodiment of the present invention, FIG. 2 is a schematic diagram of a second embodiment, and FIGS. 3 and 4 are diagrams for explaining the incident intensity and transmitted intensity of X-rays. FIG. 5 is a schematic view of a conventional example. DESCRIPTION OF SYMBOLS 1 ... X-ray tube, 2, 21, 22 ... Crystal lattice, 3 ... Collimator, 4 ... Patient, 41 ... Soft tissue, 42 ... Bone, 5 ... X
Line position detector, 6: Crest height analyzer, 7: Data processing device, 8: Scan motor.

Claims (2)

(57) [Claims] 1. A means for generating radiation, a single crystal lattice irradiated with the radiation, and two different radiation angles reflected by the crystal lattice having two predetermined reflection angles are collimated to produce two different radiations. Means for simultaneously irradiating the subject with energy radiation, radiation detecting means for transmitting these two energy radiations through the subject, and performing a wave height analysis of the output of the radiation detecting means. An apparatus for quantitatively analyzing bone minerals, comprising: a wave height analyzing means for separating transmission data regarding energy radiation; and a means for calculating the bone density by arithmetically processing the separated data. 2. A means for generating radiation, two crystal lattices to which each of the radiations is irradiated, and two different energy beams which are collimated at each of the two crystal lattices and reflected at a specific angle. Means for simultaneously irradiating the subject with radiation, radiation detecting means for transmitting radiation of these two energies through the subject, and
Bone mineral quantification comprising wave height analysis means for performing wave height analysis of the output of the radiation detection means to separate transmission data relating to radiation of each energy, and means for calculating the bone density by arithmetically processing the separated data. Analysis equipment.