Patent Application
20130108509
The present invention relates to an automatic analysis device that irradiates an object to be measured with light and measures light scattered on the object. More specifically, the invention relates to an automatic analysis device including two or more detectors.
A sample analysis device analyzes the ingredient amount contained in a sample (specimen or sample). An automatic analysis device is widely used as such a sample analysis device. The automatic analysis device irradiates a sample or a reaction solution that contains a mixture of the sample and a reagent with light from a light source. The automatic analysis device measures the amount of the resulting transmitted light having one or more wavelengths and calculates absorbance. Based on the Lambert-Beer law, the automatic analysis device estimates the ingredient amount according to a relationship between the absorbance and the concentration.
These devices include a cell disk that repeatedly rotates and stops. Many cells containing a reaction solution are circularly arranged on the cell disk. A transmitted light measuring unit of the device is previously provided and measures a time change of the absorbance for approximately ten minutes at a specified time interval while the cell disk rotates.
The automatic analysis device, including a system that measures the amount of transmitted light, uses broadly two types of reactions for reaction solutions, i.e., color reaction between substrate and enzyme and aggregation reaction between antigen and antibody.
The former is biochemical analysis and includes inspection items such as LDH (lactate dehydrogenase), ALP (alkaline phosphatase), and AST (asparate aminotransferase). The latter is immune assay and includes inspection items such as CRP (C-reactive protein), IgG (immunoglobulin G), and RF (rheumatoid factor).
The immune assay measures materials having low blood concentration and therefore requires high sensitivity. There has been an attempt to ensure high sensitivity for the latex agglutination immunoassay. The latex agglutination immunoassay uses a reagent resulting from sensitizing (binding) antibody to the surface of a latex particle to recognize and aggregate ingredients contained in a sample. For this purpose, the latex agglutination immunoassay applies light to a reaction solution and measures the amount of transmitted light not scattered on latex aggregates to determine the amount of ingredients contained in the sample.
There have been attempts to ensure high sensitivity for the automatic analysis device by measuring the amount of scattered light, not the amount of transmitted light. For an example, the system (disclosed in patent document 1) separates transmitted light from scattered light using a diaphragm and simultaneously measures the absorbance and the scattered light. For another example, the configuration (disclosed in patent document 2) improves accuracy at a high-concentration side by measuring the scattered light reflected on a large aggregate formed as a result of advanced aggregation reaction. For still another example, the method (disclosed in patent document 3) uses integrating spheres forward and backward of a reaction container, measures the average intensity of light for each of the forward scattered light and the backward scattered light, and corrects a turbidity change due to the cell position misalignment.
In an automatic analysis device which uses a detector to detect the scattered light, a foreign material such as air bubble may mix in an object to be measured or may adhere to the inside of a reaction container or the reaction container may have a flaw, causing a noise component that affects a measurement result.
To decrease the noise effect, there is a method that improves the S/N ratio characteristics by integrating an output from the detector for a specified time. However, the integration time depends on a temporal change of the object to be measured. In addition, the S/N ratio characteristics may not be improved if a foreign material such as air bubble adheres inside the reaction container. Patent document 3 discloses a technology that decreases the S/N ratio by integrating the scattered light and performing an averaging procedure.
A light scattering photometer applies light to an object to be measured and detects the scattered light. In principle, however, it is difficult for such a light scattering photometer to distinguish between the object to be measured and a flaw on the reaction container or an air bubble adhered inside the reaction container.
An air bubble often adheres to a specific location inside the reaction container. A flaw is often found at a specific location of the reaction container as well. Therefore, a highly reliable result may be obtained using a light detection signal of scattered light with less noise components if light scattered in a specific direction can be removed before the concentration calculation.
It is an object of the invention to provide an automatic analysis device which can provide a highly reliable analysis result even if scattered light contains a noise or an intermediate optical path in the optical system includes an obstacle that hinders the scattered light from passing.
According to the invention, an automatic analysis device is provided that measures intensities of scattered light from an object to be measured in a plurality of directions, obtains correlation coefficients between the intensities of the scattered light in the directions, and analyzes the object using the intensities of the scattered light in the directions, the intensities having the correlation coefficient larger than a reference correlation coefficient.
According to the invention, the intensity of scattered light having a large correlation coefficient is used to analyze an object to be measured. Therefore, a highly reliable measurement result can be obtained and provided for clinical practice.
Embodiments of the present invention will be described below with reference to the drawings.
With reference to
First, with reference to
Many sample containers 6 are placed on a sample disk 5, the sample containers containing a biological sample such as blood or urine. A pipette nozzle 8 is attached to a movable arm 7 and draws up a pre-determined amount of sample from the sample container 6 located at a suction position of the sample disk 5. The pipette nozzle 8 then discharges the sample into the reaction container 2 at a discharge position on the reaction disk 1.
A reagent disk is placed in each of reagent cool boxes 9A and 9B. Reagent bottles 10A and 10B are placed on the reagent disk and are provided with a label indicating reagent identification information, such as a bar code. The reagent bottles contain reagent solutions corresponding to analysis items analyzed by an analysis device. Bar code readers 34A and 34B are provided for the reagent cool boxes 9A and 9B, respectively, and read a bar code on the outer wall of each reagent bottle to register the reagent. The read reagent information is stored as well as the position on the reagent disk in memory 11 to be described later.
A pipette nozzle for reagent is provided for each of reagent dispensing mechanisms 12A and 12B, drawing up a reagent solution from a reagent bottle which is located at a reagent entry position on the reaction disk 1 and corresponds to the inspection item and then discharging the reagent solution into the corresponding reaction container 2.
Stirring mechanisms 13A and 13B stir a mixture of the sample and the reagent contained in the reaction container 2. A series of reaction containers 2 circularly moves to pass through a photometric position between a light source 14 and a light scattering photometer 15. The light scattering photometer 15 may be provided with a multi-wavelength absorption photometer along a coaxial light axis. The light scattering photometer 15 may perform concentration operation using both scattered light and transmitted light. The light source 14 and the light scattering photometer 15 configure an optical detection system. Placement of a light detector in the light scattering photometer 15 will be described with reference to
The reaction solution of sample and reagent in each reaction container 2 is photometrically measured each time the reaction container 2 passes before the light scattering photometer 15 while the reaction disk 1 rotates. The scattered light is measured for each sample and the analog signal of the scattered light is input to an A/D converter 16. A reaction container cleaning mechanism 17 is provided near the reaction disk 1 and cleans the inside of the used reaction container 2. This enables the reaction container to be reused.
Next, a control system and a signal processing system of the analysis device in
A computer 18 is connected to a sample-dispensing control unit 20, a reagent-dispensing control unit 21, and the A/D converter 16 via an interface 19. The computer 18 sends an instruction to the sample-dispensing control unit 20 to control sample-dispensing operation. The computer 18 sends an instruction to the reagent-dispensing control unit 21 to control reagent-dispensing operation.
The computer 18 receives a photometric value as a digital signal converted by the A/D converter 16. The interface 19 is connected with a printer 22 for printing, memory 11 and an external output medium 23 as storage devices, a keyboard 24 for entering operational instructions, and a CRT display (display device) 25 for screen display. The display device may be a liquid crystal display as well as a CRT display. The memory 11 includes hard disk memory or external memory, for example. The memory 11 stores information such as passwords for operators, display levels for each screen, analysis parameters, content of requested analysis items, calibration results, and analysis results.
An analysis operation of sample in the automatic analysis device in
Analysis parameters concerning items the automatic analysis device can analyze is input using an information input apparatus such as the keyboard 24 and stored in the memory 11 in advance. An operator selects an inspection item requested for each sample using an operation function screen to be described later.
Information such as a patient ID is also input from the keyboard 24. To analyze the inspection item specified for each sample, the pipette nozzle 8 dispenses a pre-determined amount of sample from the sample container 6 to the reaction container 2 according to the analysis parameters.
The reaction container containing the sample is transported through the rotation of the reaction disk 1 and stops at the reagent entry position. The pipette nozzles of the reagent dispensing mechanisms 12A and 12B dispense a pre-determined amount of reagent solution into the reaction container 2 according to an analysis parameter for the corresponding inspection item. The sample and the reagent may be dispensed in the reverse order of this example, namely, the reagent is dispensed before the sample is.
The stirring mechanisms 13A and 13B stir and mix the sample and the reagent. When the reaction container 2 passes through the photometric position, the light scattering photometer 15 measures the scattered light from the reaction solution. The A/D converter 16 converts the measured scattered light into a numeric value proportionate to the light intensity. The numeric value is supplied to the computer 18 via the interface 19.
The converted numeric value is further converted into concentration data based on a standard curve previously measured according to an analysis method specified for each inspection item. The printer 22 or the screen of the CRT 25 outputs ingredient concentration data as an analysis result of each inspection item.
Before the above-mentioned measurement operation is performed, the operator specifies various parameters and registers specimens needed for the analysis measurement through the operation screens on the CRT 25. The operator learns an analysis result after the measurement using the operation screens on the CRT 25.
With reference to
The light from a light source 201 enters a reaction container 202 that contains the dispensed object to be measured. The object to be measured includes the reaction container 202. The light scattering photometer 15 detects the scattered light from the object to be measured.
The light scattering photometer 15 includes four light detectors (204, 205, 206, and 207). Photodiodes are used for the light detectors. The four light detectors (204, 205, 206, and 207) are placed at different inclinations against an axis of the transmitted light (angle 0°) which is an extension of the axis of the incident light.
The light detector 204 has inclination θ1. For example, any angle between 30° and 20° may be selected for the inclination θ1. The light detector 205 has inclination θ2 greater than θ1. Any angle between 30° and 20° may be selected for an angular difference between θ2 and θ1.
The light detector 206 has inclination θ3. For example, any angle between −30° and −20° may be selected for the inclination θ3.
The light detector 207 has inclination θ4. The light detector 207 has inclination θ4 greater than θ3. For example, any angle between 30° and 20° may be selected for the inclination θ3. The light detectors are placed at different inclinations in the Z-axis direction against the axis of the incident light. The light detectors may be placed at different angles in the X-axis or Y-axis direction against the axis of the incident light or oblique to the axis of the incident light. The light detectors may be placed contiguously instead of dispersedly.
The incident light collides against the object to be measured in the reaction container 202 and scatters. The light detector 204 (θ1), the light detector 205 (θ2), the light detector 206 (θ3), and the light detector 207 (θ1) detect the scattered light. During the detection, if an air bubble or flaw 203, for example, exists in intermediate paths between the reaction container and the light detectors, the scattered light received by the light detector 207 positioned at θ4 against the axis of transmitted light (0°) is influenced.
With reference to
The graph represents a reaction process shown by the relationship between measurement points (horizontal axis) and output signals (vertical axis) which are the scattered light detected by the light detectors 204 to 205.
This reaction process is plural plots of a reaction progress over time from the beginning to the end of the measurement to detect the object to be measured at each time the reaction container, which is placed along the circumference of the reaction disk, passes before the photometer at a pre-determined time interval. In this example, the reaction process is represented by the output signals of the light detectors (204 and 205) with a time course period from a measurement point 19 to a measurement point 34. The measurement points indicate the numbers of sequence of detection by the photometer. As the number of the measurement point increases, the lapse of time increases. The time course period can be selected by any measurement points or any period range.
Generally, the amount of scattered light decreases as the inclination angle against the axis of transmitted light increases. In
With reference to
The signal value of the scattered light received by the light detector is equal to the sum of the signal components and the noise components. When the signal components are represented by a numeric value of 100±α in an ideal condition, for example, any one of the light detectors should receive a signal of the scattered light of 100±α from the same object to be measured. On the other hand, the noise components may indicate a positive or negative value because the noise components randomly affect a signal of the scattered light received by the light detectors. If the light detectors are of different types, the placement of the light detectors or difference between the light detectors affects the noise components.
The signal component may vary if some factor, such as the air bubble or flaw 203 on the reaction container as illustrated in
As can be seen from numeric values (1) and a graph (2) in
Next, the correlation between intensities of the scattered light detected by the light detectors will be described.
The least-square method is used to calculate a linear regression curve (straight line) based on a regression curve of the intensities of the scattered light detected by the light detector 204 (θ1) and the light detector 205 (θ2). An equation y=1.6776x−0.5637 represents the linear regression curve (straight line). In addition, a correlation is calculated between the intensities of the scattered light detected by the light detector 204 (θ1) and the light detector 205 (θ2) to calculate R2, statistically known as a contribution ratio, and a slope and an intercept of the regression line. The contribution ratio R2 corresponds to a correlation coefficient. The slope and the intercept are coefficients of the regression line.
The correlation coefficient of the intensities of the scattered light detected by the light detector 204 (θ1) and the light detector 205 (θ2) is 0.9929, which is close to 1 and indicates a high correlation.
As described above, the correlation between the light detector 204 (θ1) and the light detector 207 (θ4) and the correlation between the light detector 204 (θ1) and the light detector 206 (θ3) are lower than the correlation between the light detector 204 (θ1) and the light detector 205 (θ2). It is considered this result is caused by effects of obstacles such as a noise in the scattered light and an air bubble or a flaw in an intermediate path where the light passes in the optical detection system.
A highly reliable result of concentration analysis can be obtained and provided for clinical practice by excluding the scattered light highly affected by a noise, air bubble, or flaw and performing concentration analysis on a sample using a detection signal from the light detector 204 (θ1) and the light detector 205 (θ2) which detect the scattered light hardly affected by a noise, air bubble, or flaw.
The light detector 204 (θ1) is used as a reference light detector to observe the correlation. Any other light detector than the light detector 204 (θ1) may be selected as the reference light detector. It is desirable to select a reference light detector that stably detects the scattered light and is hardly affected by a noise, air bubble, or flaw. For this purpose, the reference light detector is set to have an appropriate inclination angle to stably detect the scattered light and prevent effects of a noise, air bubble, or flaw.
With reference to
In an example of
Although the regression line is used in the example of
As described above, highly precise and reliable analysis results can be obtained by performing the concentration analysis by using a standard curve of which the averaged intensities of the light are previously measured, the averaged intensities of the light being obtained by normalizing the intensities of the scattered light detected by plural light detectors which are strongly correlated with each other.
With reference to
The automatic analysis device starts concentration analysis (step 301). Then, the light detectors (204, 205, 206, and 207) obtain multi-angle data with different inclinations (detect the scattered light) (step 302).
At step 302, the light detectors (204, 205, 206, and 207) detect a change in the intensity of scattered light in terms of data of the concentration that varies reaction with time over a wide range including the measurement points 19 to 34. Data of specified periods is extracted from the wide range of the measurement points (step 303).
Any part of the range needed for the concentration analysis is selected to extract the data of the specified periods. Any of the measurement points where the reaction varies with time can be selected with any part of the range. Therefore, the concentration analysis can be performed appropriately as needed.
A correlation coefficient is obtained for data at a high angle from the intensities of the scattered light detected by the light detectors (204, 205, 206, and 207) selected at step 303 (step 304). As described above, the correlation is higher as the correlation coefficient (contribution ratio R2) is closer to 1. The correlation is lower as the correlation coefficient is closer to 0.
Data of a large correlation coefficient is extracted based on the correlation coefficient at step 304 (step 305). In this extraction process, the intensities of the scattered light of the light detectors (204 and 205) having large correlation coefficients are selected from the intensities of the scattered light detected by the light detectors (204, 205, 206, and 207). The process excludes the intensities of the scattered light having correlation coefficients smaller than a reference correlation coefficient (a threshold value) previously entered by an operator, selecting the intensities of the scattered light having large correlation coefficients.
The reference correlation coefficient is at least approximately 0.94. If the reference correlation coefficient is set to 0.9300, the intensities of the scattered light detected by the light detector 206 are not excluded and are selected as the intensities of the scattered light having large correlation coefficients. It is desirable to appropriately define a value of the reference correlation coefficient according to the accuracy level needed for the concentration analysis.
Angle data decided to have low correlation at step 305 is not used for the concentration analysis (step 306). On the other hand, angle data decided to have high correlation is normalized to an output value for a reference angle (step 307). As described above, the normalization process normalizes the data to values of the intensities of the scattered light detected by the specific light detector using the coefficient (slope and intercept) of the regression line calculated simultaneously with the correlation coefficient (contribution ratio R2).
The normalized scattered light is averaged (step 308). The concentration analysis is performed on the averaged intensities of the scattered light (step 309). The data processing is terminated (step 310).
Setting of parameters for the concentration analysis will be described below.
As described above, in the concentration analysis, the intensities of the scattered light from an object to be measured are measured and obtained in plural directions (at plural angles), reliable data being selected from the obtained data of the intensities of the scattered light and being normalized to values of the scattered light at a specified angle.
As illustrated in
A period for comparing correlations in data of the reaction process can be specified by setting a start point (403) to start the comparison and an end point (404) to end the comparison. This enables the concentration analysis to be set on a setting screen for analysis conditions of the automatic analysis device. It is desirable to select the start point (403) and the end point (404) for any time course period in consideration of the accuracy level required of the concentration analysis and the reaction process of a time-varying sample.
The conditions of the concentration analysis are not always specified from the setting screen of the automatic analysis device. If the conditions are constant, they may be specified using parameters previously stored in a storage area of the automatic analysis device.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-141430 | Jun 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/063443 | 6/13/2011 | WO | 00 | 1/14/2013 |
