WO2025087377A1 - Method for weakening effect of lipemia on transmission and scattering fusion enhanced immunoturbidimetric assay - Google Patents

Abstract

The present invention relates to the technical field of transmission and scattering fusion enhanced immunoturbidimetric assays. Disclosed in the present invention is a method for weakening the effect of lipemia on a transmission and scattering fusion enhanced immunoturbidimetric assay. The method specifically comprises the following steps: S1, measuring the mean value of absorbance signal values at a light measurement point in a specific section after a reaction buffer is added to each sample; S2, measuring non-lipemia turbidity values, i.e., backgrounds, of different samples which do not cause a relatively low scattering measurement, after the reaction buffer is added to each sample; and S3, comparing the value measured in step S1 with the values measured in step S2, so as to determine whether a scattering turbidimetric measurement result needs to be revised. In the method for weakening the effect of lipemia on a transmission and scattering fusion enhanced immunoturbidimetric assay, during the transmission and scattering fusion enhanced immunoturbidimetric assay, there is a strong correlation between the turbidity of fat particles of a lipemia sample and a transmission turbidity signal value after a reaction buffer is added to the sample, and the correlation is specifically quantified by means of transmission light absorbance values of the sample and R1.

Description

A method to reduce the effect of lipemia on transmissive fusion enhanced immunoturbidimetric detection Technical Field

The invention relates to the technical field of through-scattering fusion enhanced immunoturbidimetry detection, in particular to a method for reducing the influence of lipemia on through-scattering fusion enhanced immunoturbidimetry detection.

Background Art

Through-scattering fusion enhanced immunoturbidimetry detection is a new methodology that emerged in 2020. It is an upgrade of the original latex immunoturbidimetry. The implementation of this methodology requires both hardware and reagent foundations.

The reagents for the through-scatter fusion enhanced immunoturbidimetry are usually composed of a reaction buffer solution, marked as R1, a sensitized latex solution marked with the project antibody or antigen, marked as R2, a calibrator of known concentration, and a quality control product. The scattering detection in the through-scatter fusion enhanced immunoturbidimetry inherits all the advantages and disadvantages of the traditional scattering immunoturbidimetry. In particular, the defect that the scattering immunoturbidimetry is strongly affected by lipemia during detection is also inherited in the through-scatter fusion enhanced immunoturbidimetry. In the through-scatter fusion enhanced method, the scattering results are used in the low-concentration area, so it will be strongly affected by lipemia. Commercialized scattering turbidimetry detection, from the Siemens BN series in the 1980s to the Beckman IMMAGE800 in 2006, to this day, scattering turbidimetry detection has still not been able to solve the influence of lipemia, and its influence can only be weakened by diluting the sample and other means.

The reason is that usually the automated turbidimetric detection is carried out in a reaction cuvette, which results in a certain "thickness" of the solution. The scattered light detection is the scattered light intensity. The scattered light generated by the particles (such as antigen-antibody immune complex) in the solution close to the side of the emitting light source (front end) is blocked by other particles close to the detector side (rear end) and cannot reach the scattered light detector, which will cause the scattered light signal value to decrease. Therefore, turbidimetry usually needs to be carried out in a relatively "dilute" solution, that is, the scattered light generated by the front immune complex will not be blocked or blocked as little as possible by the particles at the back end. The influence of lipemia mainly comes from the fat particles in lipemia, which makes the concentration of particles in the tested solution become "thick", resulting in the scattered light signal value generated by the immunoturbidimetric reaction unable to smoothly reach the scattered light detector, resulting in a reduction in the signal value and an underestimated test result.

Traditional scattering turbidimetry can make "thick" particles "thin" by dilution to reduce this effect, but if the reaction solution is too dilute, it is difficult for the antigen-antibody immune reaction to occur, especially when testing items with low content of the analyte (less than 1000ug/L concentration), it is usually necessary to increase the sample volume to improve the sensitivity, and dilution is completely undesirable; at the same time, the "thickness" of lipemia in different samples is different, and the thicker the sample, the more serious the effect. Automated equipment cannot perform customized testing for each sample with a different dilution, and can only perform batch operations with a unified dilution. Therefore, to this day, traditional automated scattering detection still cannot solve the problem of lipemia. To this end, the present invention provides a method for reducing the effect of lipemia on through-scattering fusion enhanced immunoturbidimetric detection to solve the above problem.

Summary of the invention

1. Technical issues to be solved

In view of the deficiencies of the prior art, the present invention provides a method for reducing the influence of lipemia on through-scattering fusion enhanced immunoturbidimetric detection, which solves the problems mentioned in the above background technology.

(II) Technical solution

To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for reducing the influence of lipemia on through-scattering fusion enhanced immunoturbidimetric detection, specifically comprising the following steps:

S1, determining the average value of the absorbance signal value at the photometric point in a specific section after each sample is added with the reaction buffer;

S2, measuring the non-lipidemia turbidity values of different samples that do not cause a low scattering measurement after adding the reaction buffer to each sample, i.e., background;

S3. Compare the value measured in step S1 with the value measured in step S2 to determine whether the nephelometry measurement result needs to be revised.

Preferably, the value measured in step S1 is expressed as R1a, and the value measured in step S2 is expressed as R1b.

Preferably, the determination formula of the nephelometric measurement result in step S3 is: Scattering revised value = Scattering initial measurement value + Scattering initial measurement value * (LN value) * correction coefficient k, wherein LN value = selectivity The function IF((R1a-R1b)>0, (R1a-R1b), 0) outputs a value.

Preferably, the method for determining whether the initial scattering measurement value in step S3 needs to be corrected is: when R1a is greater than R1b, LN=R1a-R1b, that is, when there is a substantial lipemia turbidity value, the scattering turbidimetric measurement result is corrected; when the sample is not actually lipemia, or the particles in the lipemia are not sufficient to cause the scattering measurement result to be low, and only other factors cause R1a to have a non-zero value, then R1a is less than or equal to R1b, and the output result is 0, and the scattering turbidimetric measurement result is not corrected at this time.

Preferably, the LN value ranges from 0 to LNH (LN upper limit).

Preferably, when the scattering revision value is within the range of ±15% of the transmission result in the transmission-scattering fusion area, the revision result is valid.

Preferably, the transmission-scattering fusion zone is a zone where both scattering and transmission can output results normally, that is, an overlapping zone between the lower limit of the transmission technology limit value and the upper limit of the scattering technology limit value.

(III) Beneficial effects

The present invention provides a method for reducing the influence of lipemia on through-scattering fusion enhanced immunoturbidimetric detection. Compared with the prior art, the method has the following beneficial effects:

(1) The method for reducing the influence of lipemia on transmissive fusion enhanced immunoturbidimetric detection is that when performing transmissive fusion enhanced immunoturbidimetric detection, the turbidity of fat particles (not triglyceride or cholesterol concentration) in the lipemia sample is strongly correlated with the transmissive turbidity signal value of the sample added with reagent R1 (reaction buffer), and the correlation is specifically quantified through the transmissive light absorbance value of the sample and R1.

(2) This method of reducing the influence of lipemia on the detection of through-scattering fusion enhanced immunoturbidimetric testing can be inferred from the principle that the aforementioned lipemia fat particles increase the "thickness" of the reaction solution, thereby hindering the scattered light from reaching the light detector. The lipemia R1 transmission turbidity value (abbreviated as LN) is positively correlated with the "thickness" within a certain range, and there is a functional relationship between LN and the underestimation of the scattering measurement results within a certain range. By studying the test results of a large number of lipemia samples, it was determined that LN is strongly correlated with the magnitude of the scattering measurement results output by the through-scattering fusion enhanced method being lower than the transmission results within a certain range; at the same time, using LN The functional relationship with the underestimation amplitude of the scattering measurement result is used to correct the lipemia scattering measurement result using a certain functional relationship (formula); and the correction formula is introduced into the software system of the integrated scattering analyzer or the Lis system for patient result output, so that the final output result can be corrected, thereby enhancing the reliability of the output result.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a graph showing the relationship between wavelength and R1b provided by a method of reducing the effect of lipemia on through-scattering fusion enhanced immunoturbidimetric detection according to the present invention;

FIG. 2 is a graph showing the relationship between wavelength and LNH provided by a method of the present invention for reducing the effect of lipemia on through-scattering fusion enhanced immunoturbidimetric detection.

DETAILED DESCRIPTION

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

The embodiment of the present invention provides the following technical solutions:

1. Formula verification:

On the Hitachi 3500 transmission scattering analyzer, for the ferritin FER project, 8ul sample, 160ul R1, 80ul R2, that is, sample volume/R1 volume = 1/20, the lower limit of the transmission technology limit value is 30ng/ml, and the upper limit of the scattering technology is 450ng/ml, that is, when the transmission scattering fusion zone is 30-450ng/ml, the above method is verified at the transmission wavelengths of 570nm, 660nm, and 800nm. After calibration with the same calibration product, the lipemia samples, hemolysis samples, and icterus samples are measured to compare the differences between the scattering revision results and the transmission results. For samples with a transmission result of 0-30ng/ml, the scattering result is directly corrected because the transmission result fluctuates greatly and is unreliable, and the result is not compared with the transmission result; for samples with an initial transmission result of 30-450ng/ml, the above formula is corrected, and the corrected result is compared with the transmission result to verify the reliability of the formula; for samples with a transmission result greater than 450ng/ml, the transmission result is directly reported without correction.

Correction formula parameters:

Scattering revised value = scattering initial measured value + scattering initial measured value * (LN) * correction factor k;

At 570 nm, R1b=700, k=0.00012; LN=IF((R1a-700)>0, (R1a-700), 0);

At 660nm, R1b=400, k=0.00017; LN=IF((R1a-400)>0, (R1a-400), 0);

At 800nm, R1b=150, k=0.00025; LN=IF((R1a-150)>0, (R1a-150), 0).

Lipemia sample 2 was used up after the 570nm test, and the 660nm and 800nm tests were not completed, so it was not included in the statistics. It can be seen that for some samples with LN greater than 2000, the deviation correction effect of some samples was not good. The samples with LN less than 10000 were diluted 1/5 for re-testing. The extremely serious lipemia sample 45 was diluted 8 times for re-testing. The data are as follows:

It can be seen that at a transmission wavelength of 570nm, the revised method performs well for samples in the through-scattering fusion zone and has no effect on the determination of non-lipidemia samples. After the revision, the deviation of lipemia samples is reduced to less than 10% for all samples.

The lipemia sample 2 was used up after the 570nm test, and the 660nm and 800nm tests were not completed, so it was not included in the statistics. It can be seen that for some samples with LN greater than 1500 at 660nm, the deviation correction effect of some samples was not good. The samples with LN less than 7500 were diluted 1/5 for re-testing. The extremely serious lipemia sample 45 was diluted 8 times for re-testing. The data are as follows:

Blood sample 2 was used up after the 570nm test, and the 660nm and 800nm tests were not completed, so it was not included in the statistics. It can be seen that for some samples with LN greater than 800 at 800nm, the deviation correction effect of some samples was not good. The samples with LN less than 4000 were diluted 1/5 for re-testing. The extremely severe lipemia sample 45 was diluted 9 times for re-testing. The data are as follows:

It can be seen that at a transmission wavelength of 660nm, the revised method performs well for samples in the through-scattering fusion zone and has no effect on the determination of non-lipidemia samples. After the revision, the deviation of lipemia samples is reduced to less than 10% for all samples.

It can be seen that at a transmission wavelength of 800nm, the revised method performs well for samples in the through-scattering fusion zone and has no effect on the determination of non-lipidemia samples. After the revision, the deviation of lipemia samples is reduced to less than 10% for all samples.

2. Parameter k range verification:

Select 570nm data to show the impact of the lower limit of the k value, and select 800nm data to show the impact of the upper limit of the k value.

As the k value decreases, the revised value becomes smaller and the negative deviation increases; as the k value increases, the revised value becomes larger and the positive deviation increases; a suitable k value ensures that as many sample deviations as possible are within 15% or even 10%, minimizing the number of samples that need to be diluted and retested.

Scattering revised value = scattering initial measured value + scattering initial measured value * (LN) * correction factor k;

At 570 nm, R1b=700, k=0.00007; LN=IF((R1a-700)>0, (R1a-700), 0);

At 800nm, R1b＝150, k＝0.00028; LN＝IF((R1a-150)>0, (R1a-150), 0).

It can be seen that at 570nm, R1b=700, k=0.00007; when LN=IF((R1a-700)>0, (R1a-700), 0), there are 2 samples (lipemia sample 60 and lipemia sample 18) in the 0-LNH area with deviations exceeding negative 10%, and more samples are on the edge of negative 10%, and the revision results are not ideal.

It can be seen that at 800nm, R1b=150, k=0.00028; when LN=IF((R1a-150)>0, (R1a-150), 0), although some samples with large negative deviations in the 0-LNH region have improved, there are 2 samples (lipemia sample 59 and lipemia sample 19) with deviations exceeding positive 10%, and more samples are on the edge of positive 10%, and the revision results are not ideal.

Therefore, within the commonly used latex turbidity wavelength range of 570-800nm, the optimal k value is in the range of 0.0008-0.00027, following the principle of negative correlation with wavelength.

3. General demonstration of other projects:

Procalcitonin PCT project, 15ul sample, 150ul R1, 75ul R2 (i.e. 1/10 of the sample volume /R1 quantity), transmission wavelength 700nm, scattering angle 20 degrees, 18-34 reading points, the process of establishing a formula suitable for this project to reduce the impact of lipemia is demonstrated on the Hitachi 3500 transmission and scattering all-in-one machine.

PCT project transmission and scattering fusion zone: the upper limit of the scattering technology limit value is 2000pg/ml, and the lower limit of the transmission technology limit value is 300pg/ml. The range of 300-2000pg/ml is the transmission and scattering fusion zone. Transmission results less than 300pg/ml are unreliable, and scattering results are reported and the formula is revised, but not compared with transmission results. Transmission results greater than 2000pg/ml are reported, and the formula is not revised.

Template formula: Scattering revised value = Scattering initial measured value + Scattering initial measured value * (LN) * correction factor k;

First, based on the "template formula", the closest initial recommended R1b value of 400 and k value of 0.00017 of 660nm were entered at the transmission wavelength of 700nm, and a preliminary revised formula for the scattering output result was established. The formula was then brought into the results of at least 25 selected lipemia samples (selected from the previous lipemia samples in the range of 300-2000pg/ml), as well as 25 non-lipemia samples for comparison analysis. Considering that the PCT project 300-2000pg/ml needs to be inflammatory samples, 15 inflammatory samples and 10 ordinary samples were selected for this type of sample. After the above determination, the formula was revised, the revised deviation was compared with the initial deviation, and the reliability of the initial R1b value and k value was checked.

It can be seen that at 700nm, under the ratio of 1/10 sample size/R1, the R1a value is generally high, which is in line with the positive correlation between the R1a value and the sample size/R1 ratio. At the same time, the R1b value and k value of 660nm were brought in. The deviation was significantly improved after revision, but the negative deviation was still large. The parameters were further refined: according to the positive correlation between k and wavelength, the k value was increased to k = 0.00020; the R1b value was estimated after testing the jaundice and hemolysis samples. R1b＝500 is more preferred.

It can be seen that the samples with LN greater than 1300 have more deviations, so they are diluted 5 times and measured after dilution. Multiply the result by the dilution factor.

It can be seen that for the PCT project, through parameter refinement and optimization, very good results can be obtained by retesting with 1/5 dilution at 700nm, 1/10 sample volume/R1 volume ratio, R1b=500, k=0.00020, and LN greater than 1300. The deviation of all samples after revision is less than 10%;

Then more than 40 random samples were tested to ensure that at least 20 samples were within the through-scatter fusion zone (i.e. 300-2000pg/ml), and the parameters were retested with 1/5 dilution at 700nm, 1/10 sample volume/R1 volume ratio, R1b=500, k=0.00020, and LN greater than 1300.

Template formula: Scattering revised value = Scattering initial measured value + Scattering initial measured value * (LN) * correction factor k;

Verify and the results are as follows:

Please refer to Figures 1 and 2, a method for reducing the effect of lipemia on through-scattering fusion enhanced immunoturbidimetric detection, specifically comprising the following steps:

S1, determining the average value of the absorbance signal value at the photometric point in a specific section after each sample is added with the reaction buffer R1, i.e. R1a;

S2, determine the non-lipidemia turbidity value (i.e., "background") of different samples that do not cause a low scattering measurement after adding the reaction buffer R1, i.e., R1b, such as the absorbance signal value of the sample when adding R1 caused by the sample color, bilirubin, hemolysis, etc. This value comes from the data summary, among which different parameters such as transmission wavelength, sample volume/R1 volume ratio and other influencing factors have different specific values;

S3. Compare the value measured in step S1 with the value measured in step S2 to determine whether the nephelometry measurement result needs to be revised.

In the embodiment of the present invention, the determination formula of the scattering turbidimetric measurement result in step S3 is: scattering revised value = scattering initial measurement value + scattering initial measurement value * (LN value) * correction coefficient k, where LN value = output value of selectivity function IF ((R1a-R1b)>0, (R1a-R1b), 0). Among them, samples that are lower than the lower limit of the transmission technology limit value but within the scattering measurement range, that is, the section where the scattering result is directly output, cannot be compared with the transmission result, and are valid by default, and are directly revised according to this formula.

In the embodiment of the present invention, the method for determining whether the initial scattering measurement value in step S3 needs to be corrected is: when R1a is greater than R1b, LN=R1a-R1b, that is, when there is a substantial lipemia turbidity value, the scattering turbidimetric measurement result is corrected; when the sample is not actually lipemia, or the particles in the lipemia are not enough to cause the scattering measurement result to be low, and only other factors cause R1a to have a non-zero value, then R1a is less than or equal to R1b, and the output result is 0, and the scattering turbidimetric measurement result is not corrected at this time. The following method can be used to accumulate certain data (such as testing a certain amount of hemolysis, jaundice color samples, or turbid samples due to other reasons), debug and obtain a relatively reliable R1b value for the corresponding item, which is negatively correlated with the wavelength and positively correlated with the sample size/R1 ratio. For example, when the most common sample size/R1 ratio is 1/20, the R1b value at a transmission wavelength of 570nm is recommended to be 700; the R1b value at a wavelength of 660nm is recommended to be 400; the R1b value at a wavelength of 800nm is recommended to be 400. Recommended 150. When changing the wavelength or sample size/R1 amount, those skilled in the art follow the following method: at the same wavelength, the R1b value is proportional to the sample size/R1 amount ratio. For example, at 660nm, when the ratio is 1/20, the R1b value is 400; when the ratio is 1/10, the R1b value = (1/10)/(1/20)*400 = 800; the same applies to other wavelengths. When using different wavelengths, use the wavelength as the X-axis and the recommended R1b value as the Y-axis to create a curve graph, and preliminarily select the R1b value based on the wavelength to debug the above three methods. Within the range of ±300 of the recommended R1b value, debug the R1b value that best suits the project. As described in the above three, at 700nm and a ratio of 1/10, R1b = 500 was selected for the second step of debugging to obtain better results.

In the embodiment of the present invention, the value range of LN value is: 0-LNH (LN upper limit). The value is different for different transmission wavelengths and is negatively correlated with the wavelength. Under the transmission wavelength of 570nm, the LN range is preferably 0-2000; under the wavelength of 660nm, the LN range is preferably 0-1500; under the wavelength of 800nm, the LN range is preferably 0-800; when it is greater than the upper limit of the range, the computer software can prompt that the range is exceeded, reminding the operator to dilute it to the range for retesting. Preferably, the dilution ratio is 1/5 (that is, when LN>LNH, the sample is diluted 5 times for measurement, and the reported result is the diluted measurement result multiplied by the dilution multiple of 5). Only extremely rare extremely high-value lipemia, such as 800nm wavelength, the LN value is greater than 4000, and the dilution multiple needs to be increased so that the LN value after dilution is less than 800 before measurement. The calculation method is also reported result = diluted measurement result * dilution multiple. The LNH value is negatively correlated with the wavelength. With the wavelength as the X-axis and the LNH value as the Y-axis, a curve chart is established as shown in Figure 2. For different wavelengths, select a better LNH value within the recommended value ±20% range according to the actual modification data. As described in the above three, for a wavelength of 700nm, select LNH=1300.

Among them, the coefficient k is a specific functional relationship value of LN and the low amplitude of the scattering measurement value. The value is different for different projects and different parameters such as transmission wavelength and other influencing factors. According to the above method, a relatively reliable k value for the corresponding project can be obtained through certain data accumulation and debugging. Preferably, in the wavelength range of 570-800nm commonly used for latex turbidity, the k value is usually between 0.00008-0.00028; the k value is positively correlated with the wavelength. Preferably, the k value of the transmission wavelength of 570nm is 0.00012±0.00003; the k value of 660nm wavelength is 0.00017±0.00003; the k value of 800nm wavelength is recommended to be 0.00025±0.00003.

In the embodiment of the present invention, when the scattering revision value is within the range of ±15% of the transmission result in the transmission-scattering fusion area, the revision result is valid.

In the embodiment of the present invention, the transmission-scattering fusion area is a section where both scattering and transmission can output results normally. That is, the overlapping area between the lower limit of the transmission technology limit value and the upper limit of the scattering technology limit value.

Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims (7)

A method for reducing the effect of lipemia on through-scatter fusion enhanced immunoturbidimetric detection, characterized in that it specifically comprises the following steps: S1, determining the average value of the absorbance signal value at the photometric point in a specific section after each sample is added with the reaction buffer; S2, measuring the non-lipidemia turbidity values of different samples that do not cause a low scattering measurement after adding the reaction buffer to each sample, i.e., background; S3. Compare the value measured in step S1 with the value measured in step S2 to determine whether the nephelometry measurement result needs to be revised. According to the method for reducing the influence of lipemia on through-scatter fusion enhanced immunoturbidimetric detection as described in claim 1, it is characterized in that the value measured in step S1 is expressed as R1a, and the value measured in step S2 is expressed as R1b. According to the method for reducing the influence of lipemia on the through-scatter fusion enhanced immunoturbidimetric detection according to claim 1, it is characterized in that: the determination formula of the scatter turbidimetric measurement result in step S3 is: scatter revised value = scatter initial measurement value + scatter initial measurement value * (LN value) * correction coefficient k, wherein LN value = output value of selectivity function IF ((R1a-R1b)>0, (R1a-R1b), 0). According to the method for reducing the influence of lipemia on through-scatter fusion enhanced immunoturbidimetric detection as described in claim 3, it is characterized in that: the method for determining whether the initial scattering measurement value in step S3 needs to be corrected is: when R1a is greater than R1b, LN=R1a-R1b, that is, when there is a substantial lipemia turbidity value, the scattering turbidimetric measurement result is corrected; when the sample is not actually lipemia, or the particles in the lipemia are not sufficient to cause the scattering measurement result to be low, and only other factors cause R1a to have a non-zero value, at this time R1a is less than or equal to R1b, and the output result is 0, and the scattering turbidimetric measurement result is not corrected at this time. According to claim 3, a method for reducing the influence of lipemia on through-scatter fusion enhanced immunoturbidimetric detection is characterized in that the LN value ranges from 0 to LNH (LN upper limit). The method for reducing the influence of lipemia on the transmission scatter fusion enhanced immunoturbidimetric detection according to claim 3 is characterized in that: the scatter correction value is based on the transmission result in the transmission scatter fusion area. The revised result is valid within the range of ±15%. According to claim 6, a method for reducing the influence of lipemia on transmission-scattering fusion-enhanced immunoturbidimetric detection is characterized in that the transmission-scattering fusion area is a section where both scattering and transmission can output results normally, that is, the overlapping area between the lower limit of the transmission technology limit value and the upper limit of the scattering technology limit value.