JPH04166144A - Biological tissue measuring device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a biological tissue measuring device used in the medical field to diagnose tumors, etc. that have occurred in a living body from transmitted light images. This method uses light to measure tissues inside a living body.It has the advantage of not having the problem of radiation exposure like with X-rays, and is suitable for application in the medical field.For example, the configuration described in Japanese Patent Application Laid-Open No. 61-37227 is generally used. 6 is a schematic block diagram showing a conventional biological tissue measuring device. In FIG. 6, 101 indicates a vertical axis. A disk-shaped pedestal 102 is rotatably supported as a center.
A gantry drive unit 103 that drives the specimen 1 vertically (perpendicular to the plane of the paper) and rotates is a light source.
1 emits a light beam with a small cross-sectional area relative to 104.
05 is a collimator that converts the light beam transmitted through the object 104 into parallel light; 106 is a detector that detects the light beam from the collimator 105; 107 is the relative arrangement of the light source 103, the collimator 105, and the detector 106 on the mount 101; 109 is an interface for transmitting the converted digital signal; 1o8 is an A/D converter that converts the signal detected by the detector 106 into a digital signal; 109 is an interface for transmitting the converted digital signal;
0 is an interface 109, and a calculation device 111 that calculates the light transmittance of the subject 104 based on the digital signal sent out through the interface 109 is a storage device 112 that stores the calculation results.
is an image display device that displays calculation results as an image, and its operation will be explained below.The light beam with a small cross section is emitted from the light source 103 to the object 104. 10
Therefore, the light beam input to the detector 106 is limited to only those components whose optical axis coincides with the light beam projected from the light source 103 to the subject 104. Not affected by light scattered inside the sample 104 ~ The signal detected by the detector 106 is converted into a digital signal by the A/D converter 108 and input to the arithmetic unit 110 via the interface 109. Calculates the light transmittance of the object 104 based on the input digital signal, and
The light source 103, the collimator 105, and the detector 106 are driven and scanned on the pedestal 101 by the detection unit driving device 107 without changing their relative arrangement, and after each scan, the pedestal driving unit 102 moves the pedestal 101, the light source 103, the collimator 105, The detector 106 and the like are moved up and down, and the pedestal 101 and the like are rotated.The light transmittance is calculated as described above while repeating the above scanning, and the result is stored in the storage device 111.
However, in the configuration of the conventional example described above, only the straight light component traveling straight from the light source 103 is detected by the detector 106. However, in a living body, light scattering and absorption are large, and the output signal level is extremely low. Therefore, when the S/N is low and the propagation distance of light within the object 104 becomes long, the resolution of the transmitted image becomes low. The present invention is intended to solve the problems of the prior art as described above, which had problems such as the need for two-dimensional scanning and the need for a long scanning time. Provided is a biological tissue measuring device that can obtain a sufficient S/N ratio and therefore can increase the resolution of a transmitted image and perform sufficient measurements even if the propagation distance of light within the subject becomes long. Another object of the present invention is to provide a biological tissue measuring device that can perform scanning in a short period of time, thereby improving measurement work efficiency.Means for solving the problems mentioned above. The technical solution of the present invention to achieve
A light source that emits a light beam; a modulator that modulates the light beam emitted from the light source with a pseudo-noise signal; and a modulator that modulates the light beam emitted from the light source with a pseudo-noise signal; a detection means for detecting only a component in the same axial direction as the light source, a scanning means for scanning while maintaining the relative arrangement of the light source and the detection means, and demodulation of the received signal detected by the detection means with a pseudo-noise signal. A light source, a modulator, a detection means, and a demodulator in the above technical means are provided so as to be scannable while maintaining their relative positions, and the light beam is modulated by each of the modulators. The present invention uses the above technical means to modulate a light beam emitted from a light source with a pseudo-noise signal using a modulator. Of the light beam transmitted through the object, the detection means detects only the component in the same axial direction as the emitted optical axis direction, and the detected received signal is demodulated by the same pseudo-noise signal in the demodulator. , even if the level of the output signal of the detection means is low, the S/
Although N can be increased, the same light beam emission, modulation, and demodulation as described above can be performed using multiple systems. Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings.First, a first embodiment of the present invention will be explained. 1 is an overall schematic block diagram showing a biological tissue measuring device according to a first embodiment of the present invention. In FIG. 3 is a light source, which emits a light beam with a small cross-sectional area to the subject (living body) 4; 5 is a light source 3; A modulator is placed between the object 4 and modulates the light emitted from the light source 3 with a pseudo-noise signal. 6 is a collimator that converts the light beam transmitted through the object 4 into parallel light. 7 is a collimator that converts the light beam from the collimator 6 into parallel light. Detector 8 is light source 3 and detector 7
Detector drive unit L 9 is a detector 7 that drives and scans the objects and the like in the circumferential direction within the water surface while maintaining their relative positions on the mount 1.
A demodulator demodulates the received signal detected by the demodulator 9 using the same pseudo-noise signal as above. 10 is an A/D converter that converts the signal demodulated by the demodulator 9 into a digital signal. 11 is an A/D converter that sends out the converted digital signal. 12 is a calculation device a that calculates the light transmittance of the subject 4 based on the digital signal sent through the interface 11; 13 is a storage device that stores the calculation results; and 14 is a storage device that stores the calculation results. Next, we will explain modulation and demodulation using pseudo-noise signals with reference to Figure 2.The communication method that performs modulation and demodulation using pseudo-noise signals is known as so-called spread spectrum communication, and is the largest of its kind. Characteristics & Top: It is strong against noise in the communication path and is confidential. There are many types of pseudo noise signals. One of the most well-known ones is M.
In FIG. 2, 21 is a signal group that generates a signal to be transmitted. 5 is a modulator, which is a pseudo signal generator that generates a pseudo noise signal for modulating the signal generated by the signal source 21. 2
2 and a mixer 23 that modulates the signal and mixes the signal with a pseudo-noise signal. 9 is a demodulator, which includes a pseudo-signal generator 24 that generates a pseudo-noise signal to be used for demodulation. , a mixer 25 that demodulates the modulated signal, a mixer 25 that mixes the modulated signal with a pseudo-noise signal, and a correlator 26 that approximately calculates a correlation function from the mixed signal and detects weak signals in the noise. The operating principle of modulation and demodulation is as follows.The signal generated by the modulation signal source 21 is converted into a pseudo noise signal generated by the pseudo signal generator 22 in the modulator 5, e.g.
The same effect can be expected with any modulation method, such as amplitude modulation, frequency modulation, phase modulation, etc. Here, amplitude modulation is used. Let's take the example of the case where the modulation rate of amplitude modulation is 1, 6, and M.
The amplitude of the position corresponding to 1 in the sequence code is 1, and the − of the M sequence code is
If the amplitude at the position corresponding to 1 is 0, the amplitude change will be as shown in Figure 3. However, μ The sign of the M sequence shown in Figure 3 is only for one cycle, and in reality, The signal modulated with the 4M sequence code, which is continuously modulated with repeated cycles, is propagated through the communication channel and mixed with the M sequence signal generated by the pseudo signal generator 24 in the mixer 25 of the demodulator 9. Here, the M-sequence signals generated by the pseudo signal generators 22 and 24 have exactly the same code, even if they are generated synchronously. Although the correlation value of the signal with respect to the M-sequence signal generated by the pseudo signal generator 24 can be obtained by integrating over the time interval, there is no correlation between the 5M-sequence signal and the external noise that has entered the communication channel from outside. The output value of the correlator 26 for noise is 0. On the other hand, for signals, even if an integral value over the M sequence code length of the signal is obtained, signals with different propagation distances in the communication channel, for example, multiple reflections in the communication channel. The components with different phases caused by
As shown in the figure, the amplitude of the correlation value of the in-phase component for the M-sequence code for demodulation is set to 1, and the number of generated bits of the μM-sequence code is set to n.
Then, the amplitude of the correlation value shifted by more than the phase corresponding to the minimum code inversion width of the M-sequence code is 11/(2°-1). Also, the correlation for other pseudo-noise signals is 0, like noise. In the configuration of the present invention described above that utilizes the characteristics of modulation and demodulation using pseudo-noise signals, its operation will be explained below. The modulator 5 modulates the signal with a pseudo-noise signal, and propagates it through the living body of the subject 4 as a communication path.
The collimator 6 selects only the light component that is close to the rectilinear light in the same axial direction as the optical axis direction, and the detector 7 detects it as a received signal'.The received signal is modulated in the demodulator 9. The correlation value with a pseudo-noise signal that is the same as the used pseudo-noise signal and is synchronized is also calculated.By taking the correlation in this way, the noise component is removed from the received signal, which propagates in the living body where there is a lot of scattering and absorption. It is possible to receive even weak light with high S/M. Also, due to the phase relationship between the received signal and the pseudo noise signal of the demodulator 9, there is a phase difference of more than 1 bit corresponding to the code length of the pseudo noise signal. Then, the amplitude of the correlation output of the demodulator 9 is 1/1 of the code length.The components that are multiplely reflected in the living body, which is the subject 4, are not only removed by the collimator 6, but also a phase difference occurs. Then, the signal demodulated by the demodulator 9 is converted into a digital signal by the A/D converter 10 and sent to the arithmetic unit 12 via the interface 11. The arithmetic unit 12 calculates the light transmittance of the object 4 based on the input digital signal.Then, the light source 3
, the modulator 5, the collimator 6, and the detector 7 are driven and scanned by the detection unit driving device 8 on the pedestal 1 without changing their relative arrangement. At the end of each scan, the pedestal driving unit 2 drives the pedestal 1, the light source 3, and the modulator. 5. Move the collimator 6 and detector 7 in the vertical direction, and further rotate the pedestal 1 etc. While repeating the above scanning, calculate the light transmittance as described above μ. The results are recorded in the storage device 13, and the image display device 14
As shown above, by modulating the optical beam with a pseudo-noise signal, the S/N can be increased, and therefore,
Even if the propagation distance of light in the living body becomes long, it is possible to obtain a biological tissue measuring device with high resolution of transmitted images. 1 is an overall schematic block diagram showing a biological tissue measuring device according to a second embodiment of the present invention; Although different configurations will be explained, the features of this embodiment Ct As shown in FIG.
, . . . 1-n modulates the light emitted from the lights with pseudo-noise signals, and each modulator 5-1, . . . 5-n modulates the light A plurality of collimators 6-1 convert the light beam transmitted through the object 4 into parallel light.
,...6-n and each collimator 6-11...6-n
A plurality of detectors 7-1, . . .
7-n, and a plurality of demodulators 9-1.9- that demodulate the received signals of each detector 7-1, . . . 7-n using pseudo noise signals.
The detector drive unit 8 and the gantry drive unit 2 are arranged in parallel so that n corresponds to each set, and their relative arrangement is maintained.
Even if the modulators 5-1, . . . , 5-n are configured so that scanning can be performed by driving the Therefore, even if it is set to use a code sequence with no correlation, each light source 1-1,...
・Even if the light beams are emitted simultaneously at 1-n, they do not interfere with each other, and measurements can be performed as if they were completely independent.As a result, the S/N ratio is high and the image resolution is high. In addition, the scanning speed can be increased by n times the number of parallel light beams (as described above, according to the present invention, the light beam emitted from the light source is modulated by a pseudo-noise signal, The noise part is removed from the received signal by demodulating it with the same pseudo-noise signal that was transmitted through the object and received, so the S/N can be increased even if the level of the received signal is low. Therefore, even if the propagation distance of light inside the object becomes long, the image resolution can be increased and sufficient measurements can be made.In addition, the emission, decoding, and demodulation of the light beam can be performed using multiple systems (\ By simultaneously using uncorrelated pseudo-noise signals to modulate, the scanning speed can be increased, and therefore the efficiency of measurement work can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing a biological tissue measuring device according to a first embodiment of the present invention. FIG. 2 is a block diagram showing an example of modulation and demodulation using a pseudo-noise signal. Fig. 4 is an explanation of the correlation output value of the pseudo-noise signal. Fig. 5 is a schematic block diagram showing a biological tissue measuring device according to the second embodiment of the present invention. Fig. 6 is a schematic block diagram showing a conventional biological tissue measuring device.
3-n... Light source 4... Subject 5, 5-1,...
・5-n...Modulator 6.6-1,...6-n...
・Collimator, 7.7-1,...7-n...Detector 8...Detection unit drive device M, 9.9-1,...9-n
... Demodulation 11 10 ... A/D converter 11 ...
Interfanee person 12...Arithmetic device 13...Memory device L 14...Image display device 22.24...Pseudo signal generator 23.25...Mixed ore 26...Correlator agent Name: Patent Attorney Akira Okaji Haga 2 F
Book Figure 6, 4th Diagram”

Claims (2)

[Claims] (1) a light source that emits a light beam; a modulator that modulates the light beam emitted from the light source with a pseudo-noise signal;
A detection means that detects only the component in the same axial direction as the emitted optical axis direction of the light beam modulated by the pseudo noise signal and transmitted through the object, and maintains the relative arrangement of the light source and the detection means. A biological tissue measuring device comprising: a scanning means for scanning while scanning; and a demodulator for demodulating the received signal detected by the detection means using a pseudo noise signal. (2) multiple sets of light sources, modulators, detection means, and demodulators;
2. The living tissue measurement device according to claim 1, wherein the pseudo noise signals modulating the light beam by each of the modulators are provided so as to be scannable while maintaining their relative positions, and are set so that the pseudo noise signals modulating the light beams with each modulator have no correlation with each other with signals other than their own. Device.