JPH0433460B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a computerized tomography apparatus (hereinafter referred to as a CT apparatus) for obtaining a tomographic image of an object, particularly a subject.

(b) Conventional technology Conventional CT devices include X-ray CT devices, emission CT devices (positron CT devices, single photon CT devices), NMR/CT devices, and ultrasound
CT devices are known.

Among these CT devices, those that can observe the metabolic functions of living organisms are emission CT devices and
It is an NMR/CT device.

However, emission CT devices are for observing radiation and have the disadvantage of injecting radioisotopes (RI) into living bodies, making it impossible to avoid exposure to radiation, while NMR/CT devices are for observing electromagnetic waves, which are very strong. The disadvantage is that the device itself and its ancillary equipment are large because it requires equipment that generates a magnetic field and magnetic shielding equipment.

On the other hand, recently, it has been proposed to use light to spectroscopically study living cell tissues. [“Oxygen characteristics of myocardial tissue” by Tamura et al. “Heart” Vol.14 No.
2′82], [“Physiological significance of myoglobin” Tamura et al. “Biophysics” Vol.16 No.1′76], [“Optical
Measurement of intracellular oxygen
Concentration of Rat Heart in Vitro”
Tamura et al“ARCHIVES
“OBIOCHEMISTRY AND BIOPHYSICS”
Vol.191 No.1 November, '78].

(c) Purpose of the invention The present invention provides a device that combines light and a CT device, that is, it uses light to analyze the cellular functions of living organisms spectroscopically and two-dimensionally. The purpose is to provide a device that can perform analysis.

With the device of this invention, it is possible to quantitatively observe in a two-dimensional distribution the binding state of oxygen molecules of proteins that can bind to oxygen molecules, such as hemoglobin and myoglobin in living organisms, and also to observe the binding state of oxygen molecules such as hemoglobin and myoglobin in a living body. Oxidation and reduction states are functions of oxygen concentration and energy state, and from these oxidation and reduction states, it is possible to observe mitochondrial oxygen concentration in a two-dimensional distribution, and by observing myoglobin in an oxygen-deficient state, for example, it is possible to detect blood circulation disorders, etc. This can be useful in discovering organic disorders, their extent and their exact location.

(d) Structure of the invention The CT apparatus of the present invention transmits a light beam having a wavelength that is absorbed by the object to be measured,
This device is characterized by obtaining a two-dimensional distribution image of the object to be measured inside the object from the intensity data of the light beam, and can be called a light beam CT device.

That is, the optical CT apparatus of the present invention includes a light source means for emitting a visible light and/or near-infrared light beam to an object to be measured, and receives the light beam transmitted through the object to be measured and calculates its light intensity. a light detection means for outputting a signal corresponding to the object to be measured; a beam scanning means for transmitting the light beam at different positions relative to the object to be measured; a light beam position signal related to the beam scanning means and an output signal of the light detection means; The apparatus is configured to include a data processing means for calculating a two-dimensional distribution of the object to be measured inside the object to be measured based on the above data, and an image display means for displaying an image of the two-dimensional distribution obtained by the data means.

The wavelength of the light beam from the light source means is preferably 500nm to 1500nm when the object to be measured is a living body, but this is because wavelengths shorter than 500nm cause greater scattering within the living body, and wavelengths longer than 1500nm This is because the absorption by water in the living body increases and the transmittance of the light beam becomes extremely low.

The light beam received by the light detection means is either a monochromatic light beam with a wavelength that has a selectively high absorbance with respect to the measurement target, or a monochromatic light beam with a wavelength that has a selectively high absorbance with a selectively high absorbance with respect to the measurement target. Preferably, the monochromatic light beam is a light beam having two or more wavelengths different from that of the monochromatic light beam and having substantially the same absorbance with respect to other absorbing substances. Using light beams with two or more different wavelengths is
The main purpose is to avoid the effects of reflection, scattering, and changes in the thickness of the object. A specific example of two different wavelengths is approximately 1450n when the measurement target is moisture.
Mention may be made of a light beam with a wavelength of m, or a light beam with a wavelength of about 1450 nm and a light beam with a wavelength of about 1200 nm. In addition, when the measurement target is hemoglobin, a light beam with a wavelength of approximately 650 nm,
or a light beam of wavelength of approximately 650 nm and approximately
Mention may be made of a light beam with a wavelength of 750 nm.
By using a light beam with two wavelengths of approximately 650 nm and approximately 750 nm, only hemoglobin can be measured. This means that it is possible to observe the oxygen concentration in the living body using hemoglobin as an indicator, and at the same time, it is possible to observe the oxygen metabolism. This means that it is also possible. Hemoglobin has an absorption peak around 1000 nm,
Measurements using this wavelength are also possible. Furthermore, if the measurement target is cytochrome, approximately 850 nm
or a light beam with a wavelength of about 850 nm and a light beam with a wavelength of about 900 nm. By using a light beam with two wavelengths of approximately 850 nm and approximately 900 nm, only oxidized cytochromes can be measured, which makes it possible to observe the concentration of oxygen in living organisms and the metabolism of oxygen using cytochromes as an indicator. It means that.

In order to select the wavelength of the light beam, a monochromatic light source such as a semiconductor laser is used as the light source means, or a white light source such as a tungsten lamp or a halogen lamp is used as the light source means, and a filter or gray is used as the light source means or light detection means. It is recommended to install a spectrometer such as Teing. Examples of photodetection means include photodiodes, phototransistors, and
PbS cells can be used.

As the beam scanning means, an X-ray scanning means proposed in a known X-ray CT apparatus can be used. For example, the translation/rotation method in JP-A-50-156387, the rotation method in JP-A-50-28894, the detector all-round equipment/beam source rotation method in JP-A-52-106698, and the JP-A-51-126088. The beam source and detector all-around system can be used. In particular, the light source means and the light detection means in this invention are smaller and cheaper than the X-ray source and X-ray detector, so they can be arranged around the entire circumference of the object to be measured and electrically scanned at high speed. can be easily performed.

The data processing means proposed in known CT apparatuses can be used as the data processing means. For example, the data processing means disclosed in Japanese Patent Application Laid-open No. 50-28385 can be used.

The video display means may be a known video display means that displays images on a CRT.

(E) Embodiment 1 shown in FIG. 1 is an embodiment of the light source CT apparatus of the present invention.

The light source means 2 consists of a tungsten lamp 3 and interference filters 5 and 6, as shown in FIG.
Approximately 650n by switching rotation of interference filters 5 and 6
A beam with a wavelength of m and a beam of light with a wavelength of about 750 nm are emitted alternately.

The photodetecting means 8 is approximately connected to the photodiode 9.
It consists of an optical filter 10 that cuts out light with a wavelength of 600 nm or less. The reason for using the optical filter 10 is to prevent the influence of illumination within the measurement chamber. That is, when the measurement chamber is illuminated by a light source such as a low-pressure sodium lamp, the illumination light is filtered out by the optical filter 10 and does not affect the measurement.

The light source means 2 and the light detection means 8 are arranged to face each other, and by placing the object to be measured 0 between them, transmitted light can be detected.

The beam scanning means 11 is of a known translation/rotation type. When the translation motor 12 rotates and the belts 13a and 13b rotate, the light source means 2 and the light detector 8 are translated, and the light beam scans the object 0 to be measured while maintaining the same angle. In addition, the rotating motor 1
4 rotates and the gantry 15 rotates, the angle of the light beam relative to the object to be measured 0 changes. A position signal related to translational scanning is output from the position sensor 16, and a position signal related to angle is output from the position sensor 17.

A computer system 18 performs interaction with the operator, electromechanical control of the entire device, and data processing. That is, obtaining a profile by translational scanning is repeated at different angles to obtain a large number of profiles, from which a two-dimensional distribution of light-absorbing substances is calculated.

Since a light beam with a wavelength of about 650 nm is absorbed by hemoglobin, it is possible to obtain a two-dimensional distribution of hemoglobin from the output signal of the photodetection means 8 corresponding to a wavelength of about 650 nm. Also about
A light beam with a wavelength of 750 nm will absorb to the same extent a light beam with a wavelength of about 650 nm for oxygenated hemoglobin, and a light beam with a wavelength of about 650 nm will absorb less for deoxygenated hemoglobin. Since both wavelengths undergo large absorption, the two-dimensional distribution of oxygen concentration can be observed from the difference in the output signals of the photodetecting means 8 for both wavelengths. The correspondence between the two wavelengths and the output signal of the photodetecting means 8 is determined by a synchronizing signal for switching the interference filters 5 and 6. Furthermore, by synchronizing the timing of data collection with the heartbeat of the living body or the signal from the Seiko detector, it is possible to observe the state of metabolism in synchronization with heartbeat and respiration.

The two-dimensional distribution of the photorespiratory substance, that is, the measurement target obtained by the computer system 18 is displayed as an image on the CRT display 19.

FIG. 3 shows another example of the configuration of the light source means 2, in which the light beams of two wavelengths are transmitted by the sector mirror 7.
is alternately radiated to the object to be measured 0 by the rotation of the . A is a case where the laser diodes 20 and 21 are used, and B is a case where a dye laser device is used.
In the latter, 22a and 23a are YAG laser devices,
22a and 23b are pigments, and pigments 22a and 23
By choosing b, the wavelength can be selected relatively freely.

FIG. 4 shows the main part of another embodiment of the optical CT device of the present invention, which has a unique beam scanning means that takes advantage of the property that the optical beam can be guided by an optical fiber. .

That is, small lenses 24a, 24b...24q, 24r... are arranged around the space where the object to be measured 0 is placed. From them, optical fibers 25a, 25b
...25q, 25r... are derived, and each optical fiber 25
a, 25b...25q, 25r... to the optical fiber 27
a, 27a', 27b, 27b', ..., 27q, 27
Divide into q', 27r, 27r',... One of the two optical fibers 27a, 2
The ends of the optical fibers 7b...27q, 27r... are fixed to the fixing plate 28 in a circumferential manner, and the other optical fibers 27a',
The ends of 27b'...27q', 27r'... are also fixed to the fixing plate 29 in a circumferential arrangement. A rotating light shielding plate 30 having a through hole 31 is placed opposite to the fixed plate 28, and the light source means 2 is placed behind the rotating light shielding plate 30. Further, a rotating light-shielding plate 32 having a through hole 33 is placed opposite to the fixed plate 29, and the light detection means 8 is placed behind the rotating light-shielding plate 32.

The light beam emitted from the light source means 2 enters one optical fiber 27b whose position corresponds to the through hole 31, passes through the optical fiber 25b coupled thereto, and is emitted as a fan beam from the small lens 24b. . Light enters the optical fibers within the irradiation area of the fan beam, but only the light that enters one optical fiber 27q' whose position corresponds to the through hole 33 is received by the photodetector 8.

Therefore, if the rotating light shielding plate 30 is fixed at a certain position and the rotating light shielding plate 32 is rotated, multiple pieces of data corresponding to the fan beam can be obtained at one position, so the position of the rotating light shielding plate 30 can be changed. By repeating the same process, you can obtain enough data to calculate a two-dimensional distribution.

FIG. 5 shows the state of blood circulation in the palm of a person observed by light absorption. The palm was about 25 mm thick, and was placed between the light source means 2 and the light detection means 8, and the blood circulation state was changed by tightening or loosening the upper arm with band B. Figure 6 shows the observation results, where (a) the light source means 2 is a 50W tungsten lamp and an optical filter [transmission wavelength 1060nm, half width 20nm], and (b) the case where the light source means 2 is a 3mW laser diode [wavelength 780nm]. This is the case.
The photodetection means 8 are all silicon photodiodes, and the voltage obtained by amplifying the output signal is shown as data. In Figure 6, band B is tightened at the time indicated by the white arrow, and band B is loosened at the time indicated by the black arrow. However, when band B is tightened, the palm becomes congested, resulting in an enzyme deficiency state and an increase in light absorption. .

Note that, for example, myoglobin may be selected as the measurement target. Alternatively, a so-called contrast method or tracer method may be applied by injecting a substance (such as a chemical solution or gas) that absorbs light at a specific wavelength into the object to be measured.

(f) Effects of the invention According to the light beam CT apparatus of this invention, the following effects can be obtained.

A two-dimensional distribution of the concentration of a light-absorbing substance within an object to be measured can be obtained non-invasively.

Based on temporal changes in the two-dimensional distribution of the concentration of light-absorbing substances, the metabolic functions of living organisms can be observed and used for medical diagnosis.

It is highly safe as there is no radiation exposure.
Easy to handle and maintain.

Since the light source and detector are cheaper and smaller than the X-ray source, X-ray detector, etc., the cost of the apparatus itself can be reduced and the size can be reduced. Furthermore, there is no need for X-ray protection facilities or magnetic shielding facilities, and the cost of incidental equipment is low.

Since the wavelength of the light beam can be easily selected, observation can be performed at a wavelength suitable for the desired measurement target.

By using two or more wavelengths,
The effects of reflection, scattering, thickness of the measurement target, and absorption by light-absorbing substances other than the measurement target can be removed.

If a substance that absorbs light at a specific wavelength is injected into a living body or object and used as a contrast method or tracer method, it becomes possible to observe things that cannot be observed in their natural state.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of an embodiment of the light beam CT apparatus of the present invention, FIG. 2 is an explanatory diagram of the configuration of the light source means and light detection means in the apparatus shown in FIG. 1, and FIG. FIG. 4 is a diagram corresponding to FIG. 2, and FIG.
FIG. 5 is an explanatory diagram of an experiment in which the state of blood circulation is observed using light beams, and FIG. 6 is a graph of the experimental results shown in FIG. 1...Light beam CT device, 2...Light source means, 3...
Tungsten lamp, 5, 6...interference filter,
7... Sector mirror, 8... Light detection means, 9...
...Photodiode, 10...Optical filter, 1
1... Beam scanning device, 12... Translation motor, 1
4... Rotating motor, 16, 17... Position sensor,
18...Data processing device, 19...CRT display.

Claims (1)

[Scope of Claims] 1. A light source means for emitting a light beam of visible light and/or near-infrared light to an object to be measured; A light detection means for outputting a signal, a beam scanning means for transmitting the light beam at different positions relative to the object to be measured, and a light beam position signal related to the beam scanning means and an output signal of the light detection means. 2 of the measurement target inside the measured object
A light beam CT apparatus comprising a data processing means for calculating a dimensional distribution and an image display means for displaying the two-dimensional distribution obtained by the data processing means as an image. 2. The optical CT apparatus according to claim 1, wherein either the light source means or the light detection means is equipped with a spectroscopic means. 3. Claim 1, wherein the light source means is capable of emitting light beams of two or more different wavelengths.
3. The optical CT device according to item 1 or 2. 4. The optical CT apparatus according to claim 3, wherein the photodetector is capable of outputting output signals corresponding to light beams of two or more different wavelengths in a distinguishable manner. 5 The data processing means performs calculations between the output signals corresponding to each wavelength of the photodetection means corresponding to the light beams of two or more different wavelengths, and based on the calculation results and the light beam position signal. 5. The light beam CT apparatus according to claim 4, which calculates a two-dimensional distribution of a measurement target. 6. The optical CT apparatus according to any one of claims 1 to 5, wherein the light source means includes a tungsten lamp. 7. The light beam according to any one of claims 1 to 5, wherein the light source means includes a halogen plan.
CT device. 8. The light beam according to any one of claims 1 to 5, wherein the light source means includes a xenon lamp.
CT device. 9. The optical CT device according to any one of claims 1 to 5, wherein the light source means includes a laser device. 10. The optical CT device according to claim 9, wherein the laser device is a dye laser device. 11. The optical CT device according to claim 9, wherein the laser device is a semiconductor laser device. 12. The optical CT device according to any one of claims 1 to 11, wherein the photodetecting means includes a photomultiplier tube. 13. The optical CT device according to any one of claims 1 to 11, wherein the photodetecting means includes a photodiode. 14. The optical CT device according to any one of claims 1 to 11, wherein the photodetecting means includes a phototransistor. 15. The light beam according to any one of claims 1 to 11, wherein the photodetection means comprises a photoconductive cell.
CT device.