CN104181295A - Image processing method for quantitative analysis of multi-line colloidal gold test strip - Google Patents

Abstract

An image processing method for quantitative analysis of multi-line colloidal gold test strips is applicable to colloidal gold test strips containing two, three or more detection lines. The detection result of the colloidal gold test strip is obtained by selecting the area between the detection lines to fit the background, and then selecting the maximum value of the difference between the background fitting curve and the data curve. It can eliminate the interference of different light conditions and defective test strips, and has the advantages of simple calculation method, small amount of calculation, and can run on a low-speed processor.

Description

An image processing method for quantitative analysis of multi-line colloidal gold test strips

technical field

The invention relates to the field of quantitative analysis of colloidal gold test strips, in particular to an image processing method for quantitative analysis of the concentration of multi-line colloidal gold test strips.

Background technique

Immunogold labeling technique (ILT) is a new type of solid-phase labeling immunoassay technology developed in the early 1980s following the three major labeling techniques of enzyme immunolabelling, fluorescent immunolabeling, and radioisotope immunolabeling. It has the advantages of simplicity, rapidity, accuracy, strong specificity, high sensitivity, no pollution, and low false positive rate. The basic principle of colloidal gold immunochromatography is: with the help of capillary siphon, the sample is mixed with the colloidal gold marker sprayed on the glass fiber and moves on the nitrocellulose membrane. If the sample contains antigen (or antibody), and The colloidal gold-labeled antibody (or antigen) binds, diffuses to the detection area on the membrane, and then combines with the unlabeled antibody (or antigen) to form a gold-labeled antigen-antibody complex, which stays on the detection line and develops color, which can be intuitively displayed Test results.

There are generally two lines on the colloidal gold test strip, the detection line (abbreviated as T line) and the control line (abbreviated as C line). The T line is generally coated with another specific antibody of the analyte, while the C line is generally coated with the antibody of the colloidal gold-labeled receptor on the gold-labeled binding pad. The C line is used to detect whether the test is valid. If the color is not observed on the line, that is, the red or purple color of colloidal gold, it means that the test is invalid. The online result is not desirable and meaningless. If the color is observed on the line , the result is judged according to the color on the T line.

Colloidal gold immunochromatography is mainly used in occasions that require qualitative detection. When the concentration of the sample in the solution to be tested exceeds a certain range, there will be a more obvious color change, and vice versa. This technology is especially suitable for qualitative monitoring of diseases, to analyze whether there are abnormally elevated substances in serum and urine, such as the content of HCG in urine during pregnancy. This method simply takes whether the upper limit of the normal reference value is exceeded as the positive limit, and the detection result is a binary relationship of yes or no.

With the advancement of production technology, the quality control of NC film in colloidal gold test strips is becoming more and more stringent. Many professional manufacturers (such as Kinma-ticAutomation, etc.) provide precision liquid addition, cutting and assembly equipment, and also provide A complete set of production lines is automated, so under strict quality control conditions, immunocolloidal gold diafiltration kits and colloidal gold immunochromatography test strips with basically the same properties can be produced. It basically guarantees that the sample added in each detection will be mixed with the gold-labeled conjugate along the uniformity and speed of the NC membrane, making it possible to judge the concentration of the sample according to the color depth of the T line .

The naked eye interpretation is mainly compared with the standard color card, which has the obvious disadvantages of slow detection speed and low degree of automation. Moreover, the subjectivity of the test personnel is high, and it is impossible to guarantee that the test results are always safe and effective, and the error rate is high. The methods of using equipment for quantitative analysis mainly include: photoresistor measurement scheme, reflective optical fiber sensor measurement reflected light intensity scheme, and image sensor acquisition image scheme. Using an image sensor to collect image signals for analysis and processing is a very popular method in immunochromatography detection equipment in recent years. CCD and CMOS are two kinds of semiconductor image sensors that are commonly used now. They have very fast response time, high sampling accuracy, and less interference during sampling, which can well ensure the quality of the collected images. It is the current mainstream method to calibrate the T-line area by image processing method, then detect the gray level of this area, and use the gray level value to deduce the concentration of the sample solution.

In addition to the common colloidal gold test strips containing a C line and a T line with a total of two detection lines, such as HCG, FOB, PSA, FPSA, some colloidal gold test strips containing multiple detection lines have begun to appear on the market , one experiment can analyze multiple test results, such as three-line and four-line test strips for drug testing. When the colloidal gold method is used for allergen detection, there are even products containing more than a dozen detection lines. When using the image method for analysis, due to the interference of nucleic acid, protein, cell and tissue fragments in the determination sample; in addition, there are occasional effects of biochemical reactions, and the image quality will be somewhat disturbed. In addition, due to different volumes of sample liquid, different temperature and humidity, and different light conditions, differences in the quality of different test strips, and dust pollution, the shape of the area to be tested on the test strip will be greatly affected, and will not be a standard Rectangular shape, often with broken areas. In order to accurately extract the gray value of the reaction result, reduce the amount of calculation, make the analysis process complete on a small processor, and facilitate the miniaturization of the interpretation instrument, a fast and simple calculation method is needed, which is suitable for the interpretation of multiple detection lines , and does not require complex image processing calculations.

Contents of the invention

The object of the present invention is to provide an image processing method for a colloidal gold test strip, which is applicable to a colloidal gold test strip comprising two, three or more detection lines. It can eliminate the interference of different lighting conditions and defective test strips, and has the advantages of simple calculation method, small amount of calculation, and can run on a low-speed processor.

The invention proposes an image processing method suitable for quantitatively analyzing multi-line (greater than or equal to two lines) colloidal gold test strips. Include the following steps:

(1) Accumulate the images of the window area of the test strip along the direction perpendicular to the flow of the liquid to obtain a data curve.

(2) Select the front side of the first detection line, the rear side of the last detection line, and the middle area of each other two detection lines as the background area as the fitting area, and use the least square method to perform quadratic curve fitting to obtain this bottom fitting curve.

(3) Subtract the data curve from the fitting curve of the background, and find the maximum value of the difference in the area of each detection line of the colloidal gold test strip, which is the detection result of the detection line.

According to the research, the data curve obtained by accumulating the windowed images along the direction perpendicular to the liquid flow, in the case of the LED lighting commonly used in the current interpretation instruments, the background part has an obvious quadratic function shape. Moreover, compared with directly reading the gray value of the detection line area, the difference between the detection line data curve and the background fitting curve has a better discrimination, which can exclude the reasons of uneven liquid flow and different dryness. caused interference.

Description of drawings

Figure 1 is a schematic diagram of test strip image acquisition.

Fig. 2 is a schematic diagram of an image processing method.

Detailed ways

The invention provides an image processing method for a colloidal gold test strip, which is suitable for quantitatively analyzing multi-line (more than or equal to two lines) colloidal gold test strips. The present invention is further described below:

First, the image of the colloidal gold test strip is acquired by an image acquisition device, as shown in Figure 1. In Fig. 1, 1 is a colloidal gold test strip, and 2 is the window area of the test strip. Because only the image in the window area is meaningful for data analysis, the entire image needs to be windowed, and only the image in the window area is selected to establish an XOY coordinate system. The X axis is along the direction of liquid flow, and the Y axis is perpendicular to the direction of liquid flow. . The image of the window area is accumulated along the Y axis, and the accumulated data obtained is expressed on the Z axis. Displayed in the XOZ coordinate system is a data curve, as shown in Figure 2.

Select the front side of the first detection line, the rear side of the last detection line and the middle of each other two detection lines as the background area as the fitting area. In Figure 2, fitting is represented by a rectangular box surrounded by dotted lines. On the selected fitting area, the fitting curve can be obtained by using the least square method to fit the quadratic curve, as shown in Figure 2. The fitted line reflects the light distribution in the background area when no test strip detection line absorbs the irradiated light. Under the illumination of single or multiple light-emitting diodes as light sources, the light distribution satisfies the one-dimensional quadratic function relationship.

Subtract the data curve from the fitting curve of the background, and find the maximum value of the difference in the area of each detection line of the colloidal gold test strip, which is the detection result of the detection line. Compared with directly reading the gray value of the detection line area, the difference between the detection line data curve and the background fitting curve has better discrimination, which can eliminate the cause of uneven liquid flow and different dryness. to interfere.

Claims (1)

1. a multi-line colloidal gold test strip quantitative analysis image processing method, is characterized in that, this method comprises the following steps: (1) Accumulate the images of the window area of the test strip along the direction perpendicular to the liquid flow to obtain a data curve; (2) Select the front side of the first detection line, the rear side of the last detection line, and the middle area of each other two detection lines as the background area as the fitting area, and use the least square method to perform quadratic curve fitting to obtain this bottom fitting curve; (3) Subtract the data curve from the fitting curve of the background, and find the maximum value of the difference in the area of each detection line of the colloidal gold test strip, which is the detection result of the detection line.