JPS63277040A - Diagnostic apparatus - Google Patents

Abstract

PURPOSE:To enhance measuring accuracy, by detecting the transmission quantity of an electromagnetic wave of each wavelength in the mode fitted to the magnitude thereof. CONSTITUTION:In a phase of one cycle, a detection controller 3 takes out a mode initially set with respect to a wavelength from a memory 9 and the gain of a photomultiplier tube 58 is adjusted according to said mode by a control signal CTL' and a switch SW is changed over by a selection signal SL. By this method, since transmission quantity can be measured in the mode corresponding to the transmission quantity of the light incident to the photomultiplier tube 58, a measuring result can be obtained with good accuracy without cutting off transmission quantity data at all even when transmission quantity is much.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a diagnostic device for measuring the amount of oxygen in internal organs such as the brain tissue of humans or animals, and in particular, the present invention relates to a diagnostic device for measuring the amount of oxygen in internal organs such as the brain tissue of humans or animals, and in particular, the amount of oxygen in hemoglobin in blood and the amount in cells. The present invention relates to a diagnostic device that measures the amount of oxygen in internal organs by detecting the amount of oxygen in cytochromes using near-infrared light.

[Conventional technology]

Generally, when diagnosing the function of internal organs such as brain tissue,
Whether the amount of oxygen in the body's organs is sufficient and properly utilized is a fundamental and important parameter.The supply of sufficient oxygen to the body's organs is critical to the viability of the fetus and newborn. Oxygen is indispensable, and if the supply of oxygen is insufficient, the mortality rate for fetuses and newborns is high, and even if they survive, the aftereffects have a significant impact on internal organs. Although all organs in the body are affected by the lack of oxygen, brain tissue is particularly damaged.

In order to quickly and easily diagnose the oxygen content of such internal organs, a diagnostic device as disclosed in U.S. Pat. No. 4,281.645, issued on August 4, 1981, has been developed. ing. This type of diagnostic device detects oxygen in internal organs, especially the brain, based on near-infrared absorption spectra of hemoglobin, an oxygen transport medium in the blood, and cytochrome a and a3 in cells that perform redox reactions. It is designed to measure changes in the group. That is, near-infrared light with a wavelength range of 700 to 1300 nm has different absorption spectra αHb02 for hemoglobin bound with oxygen (HbO2) and hemoglobin from which oxygen has been removed (Hb), as shown in Figure 2(a). 'αHb is shown, and Fig. 2 (
oxidized cytochrome a, a (C
yO2) and unreduced cytochrome a, a3 (Cy)
and exhibit different absorption spectra αcyo2' α. Utilizing these properties of near-infrared light, four different wavelengths λ1. λ2. λ3゜λ4 (e.g. 775nm, 800nm, 825n!n, 850nm
) is time-divisionally incident, the amount of light that has passed through the head is sequentially detected on the other side of the head, and these four types of detection results are subjected to predetermined arithmetic processing. Changes in the concentrations of unknowns, i.e. hemoglobin bound with oxygen (HbO2), hemoglobin deoxygenated (Hb), oxidized cytochrome a,a (Cy02), and reduced cytochrome a,a3 (Cy) The system calculates the stars and uses this to measure, for example, changes in the amount of oxygen in the brain.

FIG. 3 is a schematic configuration diagram of such a diagnostic device. Third
In the figure, the conventional diagnostic device uses four different wavelengths λ1.
．． λ2. λ3. Light sources LD1 to LD4, such as laser diodes, each outputting near-infrared light of λ4, and light source L
A light source control device 55 that controls the output timing of the DI to LD4, and an optical fiber 5 that irradiates the head 60 with near-infrared light output from the light sources LDI to LD4, respectively.
〇-1 to 50-4 and optical fibers 50-1 to 50-
4, a detection side fixture 52 attached to a predetermined position of the head 60 on the opposite side to the side where the irradiation fixture 51 is attached, An optical fiber 53 is held by a fixture 52 and guides the near-infrared light transmitted through the head 60, and the number of photons of the near-infrared light guided by the optical fiber 53 is counted to measure the amount of near-infrared light transmitted. The computer system 56 controls the entire diagnostic apparatus and measures the amount of change in oxygen in the brain tissue based on the amount of near-infrared light transmitted.

The computer system 56 includes a processor 62, a memory 63, and an output device 64 such as a display or a printer.
and an input device 65 such as a keyboard, which are connected to each other by a system bus 66. Further, a light source control device 55 and a transmitted light detection device 54 are connected to the system bus 66 of the computer system 56 as external components 10 .

The light source control device W55 drives the light sources LD1 to LD4 using drive signals ACT1 to ACT4 as shown in FIGS. 4(a) to 4(d) according to instructions from the computer system 56. In FIGS. 4(a) to 4(d), one measurement period Mk (k=1.2...) consists of N cycles CYI to CYN. cycle CYI
Phase φ of any cycle CYn from CYH to
In phase n1, none of the light sources LDI to LDJ is driven, and the head 60 is not irradiated with near-infrared light from the light sources LDI to LD4. In phase φn2, the light source LDI is driven, and for example, 775 nm light is emitted from the light source LDI. Near-infrared light is output. Similarly, in phase φn3, the light source LD2 is driven and near-infrared light of, for example, 800 nm is output from the light source LD2, and in phase φn4, the light source LD3 is driven and near-infrared light of, for example, 825 nm is output from the light source LD3, and in phase φn5. Then, the light source LD4 is driven and the light source L
For example, near-infrared light of 850 nm is output from D4. In this way, the light source control device 55 is configured to sequentially drive the light sources LDI to LD4 in a time-division manner.

The transmitted light detection device 54 also includes a filter 57 that adjusts the amount of near-infrared light from the optical fiber 53, and a lens 70.7.
1, a photomultiplier tube 58 that converts the light from the filter 57 into a pulse current and outputs it, an amplifier 59 that amplifies the pulse current from the photomultiplier tube 58, and a predetermined pulse current from the amplifier 59. a pulse height discriminator 60 that removes pulse currents below a pulse height threshold; a multichannel photon counter 61 that detects the photon number frequency for each channel; and a detection controller 67, for example, that controls the detection period of the multichannel photon counter 61. A temperature controller 68 is provided to adjust the temperature of a cooler 69 housing the photomultiplier tube 58.

In a diagnostic device having such a configuration, when in use, the irradiation-side fixture 51 and the detection-side fixture 52 are firmly attached to predetermined positions on the head 60 with tape or the like, and then the light sources LD1 to LD4 are controlled by the light source control device 55. Figure 4(a)
When driven as shown in (d), four types of near-infrared light with different wavelengths are sequentially output from the light sources LDI to LD4 in a time-division manner, and are transmitted to the head via optical fibers 50-1 to 50-4. The bones and soft tissues of the head 60 that are incident on the head 60 are transparent to near-infrared light, so near-infrared light mainly affects hemoglobin in the blood, cytochrome a, a
A portion of the light is absorbed by the optical fiber 53 and output to the optical fiber 53, and is applied to the transmitted light detector RA544C from the optical fiber 53. Note that in the phase φn1 in which none of the light sources LDI to L D 4 is driven, the transmitted light detection device 54
No transmitted light from the LD 4 is incident, and at this time, dark light is detected by the transmitted light detection device 54.

The photomultiplier tube 58 of the transmitted light detection device 54 is for photon counting, which operates with high sensitivity and high response speed. The output pulse current of the photomultiplier tube 58 is transmitted to the amplifier 59.
The signal is input to the pulse height discriminator 60 via the pulse height discriminator 60. The pulse height discriminator 60 removes noise components below a predetermined pulse height threshold and inputs only signal pulses to the multichannel photon counter 61. The multi-channel photon counter 61 operates in accordance with the control signal CTL as shown in FIG. 4(e) from the detection controller 67.
) The drive signal ACT of the light sources LDI to LD4 as shown in
Period T synchronized with I to ACT4.

The number of photons detected for each wavelength of light incident from the optical fiber 53 is counted.

As a result, transmission amount data for each wavelength of near-infrared light is obtained.

That is, as shown in FIGS. 4(a) to 4(e), during one cycle CYn of the light source control device 55, in phase φn1, none of the light sources LDI to LD4 are driven, so that the transmitted light detection device In 54, dark light data d
is counted. Furthermore, in the phases φn2 to φn5, the light sources LDI to LD4 are sequentially driven in a time-division manner, so that the transmitted light detection device 54 detects four different wavelengths λ1. λ2
．． Transmission data of near-infrared light of λ3゜λ4 1. 1□2
゜λ1 1.3.1 are counted sequentially.

In this way, the dark light data d and the transmission amount data 1 . 1.
1. 1 is N times rhino λ1 λ2 person 3
Counting continues over λ4 cycles CYI to CYN. That is, with N cycles, one measurement period Mk (k
=1.2. ...), specifically, for example, one cycle CYn is 200 μs and r) N is 10
000 times, one measurement period Mk is 2 seconds. At the end of one measurement period Mk, the counting results of dark light data T , T , T , Tλ1 λ
2 λ3 λ4 (=Σ tλj/CY n ) is transferred to the computer system n=1 and stored in the memory 63.

The processor 62 stores the memory 63 in one measurement period Mh.
Transmission amount data, dark light data (T, T2.T3.T, D) λ1 Mk stored in , and M at the start of measurement. Transmission amount data, dark light data (T, Tyo, Teh...

Perform dark subtraction from λ1 T , D) and obtain λ
4 MO Thereafter, the rate of change in the amount of transmission ΔT, ΔT12°λ1 ΔT, ΔT is calculated. That is, the rate of change in the amount of transmission λ3 ΔT , ΔT , ΔT λ1 λ2 λ31 ΔTλ4 is ΔT ,=j! oq [(Tλ yaw D) Mk/λノ(T −-D) ] (J = 1 to 4) λノ
MO...(1) Calculated as follows. Note that the reason why ΔT□j is calculated using a logarithm is to express a change in optical density.

The rate of change in the amount of transmission Δ1゛, ΔT calculated in this way
λ2. ΔTλ3. From ΔTλ4, λ1 Hemoglobin combined with oxygen (HbO2), Deoxygenated hemoglobin, (Hb), Oxidized cytochrome a + a (Cy O2) + Reduced cytochrome a, a (Cy) Concentration change ΔX1lb02゜Δ
To detect X ΔX and ΔX respectively, Hb'
CVO2CV is possible. That is, the concentration change ΔX11 of each component. . 2
゜ΔX ΔX ΔX is detected as 11bl CVO21cy (2). Here α1. is each component i (Hb
is the absorption coefficient of O, Hb, Cy O2, Cy),
It is predetermined from FIGS. 2(a) and (b).

Further, 1 is the length of the head 60 in the direction in which near-infrared light travels.

The concentration change ΔX11 of each component detected in the computer system 56 in this way. . 2゜ΔXXAX
In other words, 11blCy021Cy is a change in the amount of oxygen in the brain, so by outputting these to the output device 64, it is possible to know and diagnose the change in the amount of oxygen in the brain.

[Problem that the invention seeks to solve]

By the way, the amount of near-infrared light transmitted varies significantly on the order of 10 to 105 depending on the size of the head 60, that is, the length ρ of the head 60 in the direction in which the near-infrared light travels. The difference is on the order of 101 to 102 depending on the wavelength. On the other hand, the dynamic range of the photomultiplier tube 58 is 10
It is on the order of 2. For this purpose, conventionally, the standard for detecting the amount of transmission, that is, the number of photons, in the transmitted light detection device 4 is set to the lowest number of photons, and when the amount of transmission is large, the filter 57 is manually adjusted. The transmitted light I entering the photomultiplier tube 58 is attenuated by this method so that it falls within the dynamic range of the photomultiplier tube 58.

However, in the conventional diagnostic device, the filter 57 had to be adjusted manually, which resulted in poor measurement efficiency.
Furthermore, when the amount of transmission is large, the filter 57 is narrowed down to reduce the amount of transmission incident on the photomultiplier tube 58, and the obtained information on the amount of transmission is discarded, so there is a problem that measurement accuracy cannot be improved.

An object of the present invention is to provide a diagnostic device that can improve measurement efficiency and measurement accuracy.

[Means for solving problems]

The present invention includes a plurality of light sources that sequentially output near-infrared light of different wavelengths, and a transmission amount detection means that sequentially detects the amount of transmission of the near-infrared light output from the plurality of light sources and transmitted through internal organs. The above-mentioned problems of the prior art can be solved by a diagnostic device characterized in that the transmission amount detection means detects the transmission amount of near-infrared light of each wavelength in a mode suitable for each wavelength. This is an attempt to improve.

[Effect]

In the present invention, near-infrared light of different wavelengths sequentially output from a plurality of light sources is incident on internal organs, and the amount of near-infrared light transmitted through the internal organs is measured sequentially for each wavelength by a transmission amount detection means. It is designed to be counted.

Incidentally, since the size of internal organs varies from patient to patient, the amount of permeation also varies from patient to patient. The amount of transmission also varies depending on the wavelength. In order to accurately detect the amount of transmission that varies in this way, in the present invention, the amount of transmission of near-infrared light of each wavelength is detected in a mode suitable for each size. When the amount of transmission is small, detection is performed in photon counting mode, and when the amount of transmission is large, detection is performed in analog detection mode.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a top view of an embodiment of a diagnostic device according to the present invention. In FIG. 1, the same parts as in FIG. 3 are given the same reference numerals, and their explanations are omitted.

In the diagnostic device 1 shown in FIG. 1, the transmitted light detection device 2 is a detection controller that controls the detection period of the multichannel photon counter 61 and adjusts the gain by adjusting the voltage applied to the photomultiplier tube 58. It has 3.

That is, the detection controller 3 controls the multi-channel photon counter 61 according to instructions from the computer system 2.
At the same time as *Ifn the detection period of
It is photoelectrically converted by the amplifier 59. Photomultiplier tube 5 according to the magnitude of the current amplified and pulse height discriminated by pulse height discriminator 6o
The applied voltage of 8 is adjusted. The voltage applied to the photomultiplier tube 58 is controlled by the control signal CTL.
' is carried out based on '.

Furthermore, in this embodiment, the filter value of the filter 4 is set based on the case where the amount of transmitted light from the optical fiber 53 is the smallest. Therefore, when the amount of transmitted light from the optical fiber 53 is small, the photomultiplier tube 58
A predetermined amount of transmitted light is incident on the photomultiplier tube 58, and a pulse current is extracted from the photomultiplier tube 58. Based on this, the detection controller 3 adjusts the applied voltage, that is, the gain of the photomultiplier tube 58, to the photomultiplier tube 58. is controlled so that it is in photon counting mode. Further, when the amount of transmitted light from the optical fiber 53 is large, a large amount of transmitted light enters the photomultiplier tube 58, and an analog current is extracted from the photomultiplier tube 58, which is then detected. The controller 3 controls the gain of the photomultiplier tube 58 so that the photomultiplier tube 58 is in the analog detection mode.

The transmitted light detection device 2 of the diagnostic device 1 shown in FIG.
A conventional multi-channel photon counter 61 that digitally counts the number of pulse currents outputted from the photomultiplier tube 58, that is, the number of photons output from the photomultiplier tube 58 when the amount of transmission to the photomultiplier tube 58 is large. An analog detector 5 for detecting an analog current is provided. The selection signal SL from the detection controller 3 determines whether the output current from the photomultiplier tube 58 is counted by the multichannel photon counter 61 or detected by the analog detector 5.
This is done by switching the switch SW.

Note that the analog detector 5 has a wide dynamic range, and the analog current value detected by the analog detector 5 is A
The signal is A/D converted by a /D converter 6 and sent to a computer system 7.

Computer system 7, like conventional computer system 56, includes a processor 8. Memory 9, output device 1
0. Although the input device 11 is connected to the system bus 12, the computer system 7 is further provided with a function to control the detection M unit 3 as described above.

In the diagnostic device 1 having such a configuration, the filter value of the filter 4 is set in advance based on the case where the amount of transmitted light from the optical fiber 53 is the smallest.
The amount of transmitted light incident on the photomultiplier tube 58 varies greatly depending on the size of the head 60 or the amount of absorption due to the wavelength of the head 60.

Therefore, before using the actual diagnostic device, it is necessary to determine whether the amount of transmitted light that passes through the patient's head 60 and enters the photomultiplier tube 58 is small and the mode is set to photon counting, or the amount of transmitted light is large and the mode is set to analog detection mode. It is necessary to conduct an initial test to determine whether the

This initial test is performed at the beginning of the diagnosis. can be done. That is, M at the start of diagnosis. One cycle of CYn
In phase φn2, near-infrared light with a wavelength λ1 is output from the light source LD1, and the transmitted light with a wavelength λ1 that has passed through the head 60 enters the photomultiplier tube 58 via the filter 4. The photomultiplier tube 58 outputs an output current commensurate with the amount of transmission, and this output current is sent to the detection controller 3.

Similarly, M at the start of diagnosis. Phase φn3. of one cycle CYn. φn4. Also at φn5, the light source LD2.
LD3. Wavelength λ2. from LD4. Near-infrared light of wavelengths λ3 and λ4 are sequentially outputted, and wavelengths λ2, . λ3.
The transmitted light of λ4 passes through the filter 4 to the photomultiplier tube 58.
are incident sequentially on a time-sharing basis. From the photomultiplier tube 58,
An output current corresponding to each amount of transmission is output and sent to the detection controller 3. In this way, based on the output current for each wavelength output during a predetermined number of cycles CYI to CYN of Mo at the start of diagnosis, the detection controller 3 determines whether this is the photon counting mode or the analog detection mode, and The determination result is stored in the memory 9 of the computer system 7, and the mode for each wave and cloud is thereby initialized.

The modes for each of the wavelengths λ1 to λ4 initially set in this way are used in each cycle CYI to CYN of one measurement period Mk during which actual diagnostic measurements are performed. That is, the phase φ of one cycle CYn of one measurement period M
At n2, the detection controller 3 retrieves the mode initially set for the wavelength λ1 from the memory 9, adjusts the gain of the photomultiplier tube 58 with the control signal CTL' according to this mode, and further switches the gain of the photomultiplier tube 58 with the selection signal SL. For example, if the mode of the wavelength λ1 stored in the memory 9 is the photon counting mode, the detection controller 3 adjusts the photomultiplier tube 58 to a gain suitable for the photon counting mode, and switches the switch. Switch the SW to the multi-channel photon counter 61.

Phase φn3 of one cycle CYn. φn4, φn
In the same manner, the detection controller 3 detects the wavelength λ2 .
λ3. The modes initially set for λ4 are each retrieved from the memory 9, and the gain of the photomultiplier tube 58 is adjusted according to these modes using the control signal CTL', and the switch SW is switched using the selection signal SL.

In this way, the amount of transmission can be measured in a mode suitable for the amount of transmission incident on the photomultiplier tube 58, so even when the amount of transmission is large, the obtained transmission amount information is not discarded and accurate measurement can be performed. You can get results.

In the above embodiment, M at the start of diagnosis. However, without performing such initial settings, the photon counting mode and analog detection mode can be time-divisionally switched within one phase, regardless of whether the amount of transmission is large or small. The amount of transmission in both modes may be counted; in this case,
Since the transmitted amount data counted in the photon counting mode and the analog detection mode are stored in the memory 9 at the end of one measurement period Mk, the processor 8
It determines which of these is appropriate, selects it, and outputs the result to the output wave 210.

〔Effect of the invention〕

As explained above, according to the present invention, the amount of transmitted near-infrared light of each wavelength is detected in a mode suitable for each size, so there is no need to manually operate the filter. The measurement efficiency can be improved, and at the same time, even if the amount of transmission is large, the amount of transmission can be detected without cutting off any information contained therein, so the accuracy of measurement can be improved.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of a diagnostic device according to the present invention, and FIG.
Figures (a) and (b) are diagrams showing the absorption spectra of hemoglobin and cytochrome, respectively, Figure 3 is a configuration diagram of a conventional diagnostic device, and Figures 4 (a) to (d) are diagrams showing the absorption spectra of hemoglobin and cytochrome, respectively. Time chart, Figure 4 (e
) is a time chart of the 'M control signal CTL. l...Diagnostic device, 2...Transmitted light detection device, 3...
Detection controller, 4... Filter, 5... Analog detector, 6... A/D converter, 7... Computer system, 8... Processor, 9... Memory, 10...
・Output device, 58... Photomultiplier tube, 61... Multi-channel photon counter, LDI
~LD4...Light source patent applicant Hamamatsu Photonics Co., Ltd. Agent Patent attorney Masaharu Uemoto Figure 2 Procedural Amendment (teacher) 7 September 3, 1985 1 Indication of the case 1988 Patent Application No. 110472 Address: 1126 Ichino-cho, Hamamatsu City, Shizuoka Prefecture Name: Hamamatsu Photonics Co., Ltd. Representative: Teruo Uma 4 Agent Address: (Postal code: 140) 3-20-7 Higashioi, Tokyo Parts Ward (1) Details (2) Contents of amendment to the "Detailed Description of the Invention" column of the specification (1) The claims are amended as shown in the attached sheet. (2) In the 2nd page of the specification, lines 10 to 11, the phrase "internal organs" is corrected to "object to be measured such as internal organs." (3) Specification 8, page 2, line 13, page 14, line 6, page 14, line 8, page 14, line 10, page 14, line 16
line, page 14, line 17, page 15, line 4, line 22
In the 7th line of the page, "near infrared light" is corrected to "electromagnetic waves". (4) Specification page 2, line 14, page 14, lines 7 to 8, page 14, line 16, page 14, lines 16 to 17, page 14 In the 20th line, "internal organ" is corrected to "object to be measured." (5) On page 14, line 7 of the specification, the phrase "a plurality of light sources and a plurality of light sources" is corrected to "a light source and a light source." (6) Delete "plurality" on page 14, line 15 of the specification. (7) In the specification, page 14, line 20, and page 15, line 1, the words "patient" are corrected to "object to be measured." (8) On page 16, line 9 of the specification, and on page 18, line 9, “
Correct "filter value" to "transmittance". (9) [Delete J for patient from lines 14 to 15 on page 18 of the specification. (10) Between the fourth and fifth lines of page 22 of the specification:
In the above embodiment, a plurality of light sources are used. However, it is also possible to use only one white light source and generate electromagnetic waves of different wavelengths by filter operation. It can be applied not only to the field of diagnosis but also to a broader field of diagnosis or measurement, and the diagnostic target is not limited to internal organs, but can also be general objects to be measured such as pieces of meat, and it can also be applied to electromagnetic waves from light sources. Claims 1) 1) 1) 1 violet of different wavelengths are sequentially 1 ζ, 1 ζ, 1 ζ of light 1)
The transmission amount detecting means sequentially detects the amount of transmission of one phoenix of each wavelength that is output from and transmitted through the Tokiko. A diagnostic device characterized in that it detects in an adapted mode. 2) When the amount of permeation is small, the permeation amount detection means:
The diagnostic device according to claim 1, wherein the amount of transmission is detected in a photon counting mode, and when the amount of transmission is large, the amount of transmission is detected in an analog detection mode. 3) The diagnostic apparatus according to claim 1, wherein the transmission amount detection means initially sets a mode for each wavelength at the time of starting diagnosis. 4) The transmission amount detection means detects the transmission amount in each mode for each wavelength, and selects an appropriate one among the detected transmission amounts in each mode to obtain the measurement result. A diagnostic device according to claim 1.

Claims (1)

[Claims] 1) A plurality of light sources that sequentially output near-infrared light of different wavelengths, and a transmission amount that sequentially detects the amount of near-infrared light output from the plurality of light sources and transmitted through internal organs. and a detection means,
A diagnostic device characterized in that the transmission amount detection means detects the transmission amount of near-infrared light of each wavelength in a mode suitable for each size. 2) When the amount of permeation is small, the permeation amount detection means:
The diagnostic device according to claim 1, wherein the amount of transmission is detected in a photon counting mode, and when the amount of transmission is large, the amount of transmission is detected in an analog detection mode. 3) The diagnostic apparatus according to claim 1, wherein the transmission amount detection means initially sets a mode for each wavelength at the time of starting diagnosis. 4) The transmission amount detection means detects the transmission amount in each mode for each wavelength, and selects an appropriate one among the detected transmission amounts in each mode to obtain the measurement result. A diagnostic device according to claim 1.