A system for measuring the filling percentage of blood collection capillaries.

Abstract

A system and method for measuring the percent fill of a blood sampling capillary includes a chamber for receiving a sample capillary containing a blood sample, an illuminator provided for illuminating the sample capillary, an imaging lens aligned with the chamber and the sample capillary, an imaging sensor aligned with the imaging lens for receiving an image of blood in the sample capillary from the imaging lens and converting the image into image data, a microcontroller circuit electrically connected with the imaging sensor, and at least one of a host computer or a user interface electrically connected with the microcontroller unit, the microcontroller circuit processes the image data to obtain a percent fill result that is sent to the host computer or at least one of a user interface.

Description

Detailed Description of the Invention

[0001] [Background of the Invention] 1. Field of the Invention The present invention generally relates to a capillary filling imaging system. Specifically, the present invention relates to a capillary filling imaging system and a method for measuring the filling percentage of a blood sample collection capillary.

[0002] 2. Description of the Related Art For diagnostic, screening, staging, drug testing, pregnancy testing, forensic analysis, and other reasons, many clinical tests on analytes are performed on biological samples. A few qualitative tests have been simplified into simple kits for patient use, but the majority of quantitative tests still require sophisticated instruments in a laboratory environment and the expertise of trained technicians.

[0003] In recent years, instruments and systems called point-of-care instruments operable by nurses and / or caregivers in hospitals, emergency medical centers, clinics, etc. have been developed, and reliable results can be obtained by nurses and / or caregivers receiving minimal training on the instruments.

[0004] In such point-of-care settings, whole blood samples are typically obtained by puncturing the patient's skin and collecting a blood sample using a capillary tube. When using a capillary tube for blood collection, it is essential to collect a sufficient volume of blood to perform the desired test, but it is desirable to obtain only the necessary amount of blood. One problem associated with some puncture devices and / or testing equipment is that the amount of blood required to obtain accurate test results is not always obtained. To obtain a suitable blood sample, the user is required to hold the capillary tube over the blood sample until it is filled to the correct level. If an insufficient amount is obtained, the test result may be incorrect, and the test sample is wasted. However, a more serious problem is that if an insufficient sample volume is obtained, the user may rely on an inaccurate and erroneous test result. Clearly, erroneous results must be avoided because they involve medical issues of a potentially serious nature.

[0005] Several prior art devices have been used to attempt to determine the filling level in liquid systems. U.S. Patent Application Publication No. 2014 / 0105446-A1 (Maxey et al., 2014) discloses a computer-based method, software, and system for determining the properties of a well fluid. The computing system receives an image of a first sample of well fluid filling a conduit to its threshold capacity. Based on the image of the first sample, the computing system determines a first lifespan for the first sample of well fluid filling the conduit to its threshold capacity. The computing system receives an image of a second sample of well fluid filling the conduit to its threshold capacity. Based on the image of the second sample, the computing system determines a second lifespan for the second sample of well fluid filling the conduit to its threshold capacity. Based on the difference between the first lifespan and the second lifespan, the properties of the well fluid are determined. This patent publication also mentions the use of capillary action to fill conduit tubes and to correlate the number of pixels in an image based on the fluid level in those tubes.

[0006] U.S. Patent No. 6,960,287 (2005, Steven C. Charlton) discloses a system for detecting underfilling for inspection sensors. The inspection sensor comprises a capillary channel for collecting a liquid sample and a conductor located outside the capillary channel. The conductor is in fluid communication with the capillary channel. When a liquid inspection sample is collected and moved through the capillary channel, the sample comes into contact with the conductor and emits a signal indicating fullness.

[0007] U.S. Patent No. 8,936,713 B2 (Rodgers et al., 2015) discloses a method and system for filling sufficiency. The system discloses a test strip comprising a first working electrode, a reference electrode, and a second working electrode. The method predicts a second current estimated around a second time interval for a given batch of test strips during the test procedure, using allowable filling data from known first and second currents. The estimated second current around the second time interval is compared with a measured actual second current around the second time interval during the actual test, and it is determined whether the measured actual second current is substantially equal to the estimated second current or within an allowable percentage deviation from the estimated second current to determine whether there is a sufficient volume of physiological fluid sample in the test strip.

[0008] [Overview of the prefecture] Because blood testing equipment can perform analysis with less blood than required, the reported values ​​of the analysis may be inaccurate. Systems for measuring the percentage volume of blood filling a capillary should ideally provide an instrument / analyzer that either includes a numerical value to correct the reported value or a signal to inform the user that the blood sample was insufficient, thereby preventing inaccurate results from being reported to the user due to the inability to report a value.

[0009] As mentioned in the Prior Art section, certain literature describes a capillary underfill detection system that uses two electrodes to detect the filling level. This requires the addition of electrodes to the capillary, increasing the cost of the capillary. Another prior art document describes the use of an imaging device to confirm the flow of sample in the capillary, but does not describe how to use the imaging device to measure the amount of sample.

[0010] The object of the present invention is to provide a system and method for capturing an image of a sample capillary and analyzing the image to determine the filling percentage of the capillary.

[0011] The present invention achieves these and other objectives by providing a system for measuring the filling percentage of a sample capillary. In one embodiment of the present invention, the system comprises a chamber for receiving a sample capillary containing a blood sample; an illuminator provided for illuminating the sample capillary; an imaging lens aligned in line with the chamber and the sample capillary; an imaging sensor aligned in line with the imaging lens, which receives an image of the blood in the sample capillary from the imaging lens and converts the image into image data; a microcontroller circuit electrically connected to the imaging sensor; and at least one of a host computer or a user interface electrically connected to the microcontroller unit, wherein the microcontroller circuit processes the image data to obtain a filling percentage result, and the filling percentage result is sent to at least one of the host computer or the user interface.

[0012] In one embodiment of the present invention, the system comprises a luminaire which is a white light LED.

[0013] In another embodiment of the present invention, the system further comprises an aperture structure aligned in a line with the imaging lens and the imaging sensor, the aperture structure being positioned between the imaging lens and the imaging sensor. The aperture structure restricts the ray cone of the image of the blood in the sample capillary, thereby reducing image distortion and aberrations caused by the imaging lens.

[0014] In another embodiment, the microcontroller circuit controls the illuminator.

[0015] In yet another embodiment, the microcontroller circuit includes software that extracts pixels whose pixel values ​​in an image of a blood-filled capillary are within a specific range of hue.

[0016] In a further embodiment, the software converts the image data into a first type of hue space and a second type of hue space.

[0017] In another embodiment, the first type of hue space is a color space of the YCbCr format.

[0018] In one embodiment, the second type of hue space is a color space in HSV format.

[0019] In one embodiment, the software is an interpreted high-level general-purpose programming language that includes a first algorithm for converting an image to the YCbCr color space and a second algorithm for converting an image to the HSV color space.

[0020] In one embodiment, image data in a first type of hue space and image data in a second type of hue space are subjected to a mask generation function to generate two masks, a YCbCr color space mask and an HSV color space mask, based on a selected hue range. Pixels within the selected hue range are set to 1 in the mask, and pixels outside the selected hue range are set to 0.

[0021] In one embodiment, a one-dimensional array is generated from a combination of two masks.

[0022] In one embodiment, the system further comprises a reference capillary known to be 100 percent filled with blood, or a reference capillary known to be 100 percent filled with a blood substitute having the required red hue, wherein image data of the reference capillary determines a calibration value for determining the filling percentage of the sample capillary.

[0023] In another embodiment, a method for measuring the filling percentage of a sample capillary containing a blood sample is disclosed. This method comprises: a) placing the sample capillary in the system for imaging analysis; b) capturing an image of the sample capillary and converting the image into image data; c) sending the image data from the captured image to a microcontroller circuit including software that processes the image data into a first type of hue space data and a second type of hue space data; d) sending the first type of hue space data and the second type of hue space data to a corresponding mask generation function to generate two masks based on a selected hue range; e) combining the two masks to generate a one-dimensional array; and f) determining the filling percentage result of the sample capillary by comparing the value generated by the analysis of the one-dimensional array with a calibration value.

[0024] In one embodiment, the determination step includes calculating the difference between the starting position of the blood sample in the image of the sample capillary and the ending position of the blood in the image of the sample capillary, and multiplying the difference by a calibration value.

[0025] In one embodiment, a method for generating a calibration value used in the system described in claim 1 is disclosed. The method comprises generating a calibration value using a reference capillary known to be 100% filled with blood, or a reference capillary known to be 100% filled with a substitute substance having the required red hue; sending the reference capillary known to be 100% filled to the previously disclosed steps a), b), c), d), e); and calculating the calibration value. [Brief explanation of the drawing]

[0026] [Figure 1]A schematic diagram showing a figure of the capillary imaging device of the present invention, showing a capillary filled with blood, a light source, an imaging sensor, an imaging lens, an arbitrary aperture structure, a microcontroller circuit, and a host computer or analyzer and / or user interface. [Figure 2] A flowchart showing general steps in a process for determining the filling percentage of a sample capillary containing a blood sample. [Figure 3] A color image of a capillary containing a blood sample, showing a fully filled capillary together with a blood start line and a blood end line. [Figure 4] A mask of a color image of a partially filled capillary segmented by hue. [Figure 5] A graph display of the sum of the mask pixels in the column direction. [Figure 6] The calculation result of capillary filling superimposed on the capillary image of a partially filled capillary, where the start and end points of the blood in the capillary determined by the algorithm are indicated by vertical lines.

Mode for Carrying Out the Invention

[0027] [Detailed Description of the Invention] Embodiments of the present invention are illustrated in Figures 1 to 6. Figure 1 is a diagram of a capillary imaging system of the present invention, illustrating one embodiment. The capillary imaging system 10 comprises a capillary 20 containing a blood sample to be imaged and a fill percentage to be determined, an illumination source 30, an imaging sensor 40, an imaging lens 50, an optional aperture structure 80, a microcontroller circuit 60, and a host computer or analyzer and / or user interface 70. The illumination source is a light source such as a white LED. The image of the capillary 20 is projected onto the imaging sensor 40 by the imaging lens 50. The imaging sensor 40 communicates with the microcontroller circuit 60, which also controls the illumination source 30. Image data from the imaging sensor 40 is processed by the microcontroller circuit, and the results are sent to the host computer or analyzer and / or user interface 70. The fill percentage results may be presented to the user of the system, or further processing may be performed by the host computer or analyzer. For example, the host computer may control the entire analyzer with other subsystems, or it may use the fill percentage results from the microcontroller circuit 60 for further calculation and / or correction of the analyte measurements.

[0028] Figure 2 is an explanatory diagram of the process for determining the filling percentage of a sample capillary containing a blood sample using the system described above. The outline of the process is as follows: In step 1 (100), an image of the sample capillary is captured. In step 2 (110), the captured image is converted to two different hue spaces. In step 3 (120), the images in the two new hue spaces are subjected to a mask generation function, with one mask generation function applied to each of the two hue spaces. Then, in step 4 (130), the masks of the first hue space and the mask of the second hue space are summed / combined pixel by pixel to obtain a one-dimensional array by combining the results of the two generated masks. In step 5 (140), erosion and dilation operations are optionally applied to the one-dimensional array to reduce noise. In step 6 (150), the blood start position 80 and blood end position 82 in the image of the sample capillary 20 are determined. In step 7(160), the difference between the blood start position 80 and the blood end position 82 is multiplied by a calibration value to determine the filling percentage of the sample capillary 20.

[0029] [Process for calculating fill percentage from capillary images] Referring to Figure 3, a typical image of a capillary containing a blood sample collected from a system like the one shown in Figure 1 is presented. For illustrative purposes only, the capillary in this image is completely filled to 100%. The software or code used to calculate the filling percentage from the capillary image is written in the Python programming language. Python is an interpreted, high-level, general-purpose programming language. Python's design philosophy emphasizes code readability through the significant use of indentation. Python's language structure and object-oriented approach are designed to help programmers write clear and logical code, from small to large-scale projects.

[0030] Many of the most widely used programming languages ​​(e.g., C++, Java, Python, etc.) are multi-paradigm and, typically in combination with imperative and procedural programming, support object-oriented programming to a greater or lesser extent. Major object-oriented languages ​​include Java, C++, C#, Python, R, PHP, Visual Basic.NET, JavaScript, Ruby, Perl, SIMSCRIPT, Object Pascal, Objective-C, Dart, Swift, Scala, Kotlin, Common Lisp, MATLAB, and Smalltalk. Although this method uses the Python language, those skilled in the art can rewrite this method, written in Python code, in any object-oriented language, including those listed above.

[0031] The next step in this process is to select the region of the capillary containing the blood sample. One way to do this is to extract pixels whose values ​​fall within a specific range of hue. In this invention, the image is converted to two hue spaces, namely YCbCr and HSV. YCbCr is typically used for digital coding of color information suitable for the compression and transmission of video and still images, such as MPEG and JPEG. HSV (hue, saturation, value), also known as HSB (hue, saturation, luminance), is frequently used by artists. This is because it seems more natural to think of color in terms of hue and saturation rather than in terms of additive or subtractive color components. HSV is a conversion of the RGB color space, and its components and colorimetry are related to the RGB color space from which HSV is derived. Once converted, the image in the new color space is subjected to a mask generation function.

[0032] The function call to execute this is as follows: 1) Yimg = MT9M114_rgb_to_ycbcr(img) 2) Himg = rgb_to_hsv(img) 3) BWY = createMask(Yimg, 0, 255, 0, 255, 143, 255) 4) BWH = createMaskHSV(Himg, 240, 20, 51, 255, 0, 255)

[0033] The input to the mask generation call indicates the hue range to be selected. Pixels within those values ​​are set to 1 in the mask, and pixels outside that range are set to 0. The results of the two masks are combined pixel by pixel using the following logical OR statement. 5) import numpy as np 6) BWYH = np.logical_and(BWY,BWH)

[0034] The resulting arrays of 1s and 0s are summed column by column into a one-dimensional array. 7) sBWYH = np.sum(BWYH,0)

[0035] [Algorithm for converting images to YCbCr format (Python language)] To convert the captured images to YCbCr format, the following algorithm is used in Python.

[0036]

number

[0037] [Algorithm for converting images to HSV format (Python language)] To convert the captured images to HSV format, the following algorithm is used, employing the Python language.

[0038]

number

[0039] [Algorithm for generating hue masks (Python language)] The following algorithm is used in Python to generate the hue mask.

[0040]

number

[0041] [Algorithm for finding threshold transitions (Python language)] To find the threshold transition from the one-dimensional array in the column direction calculated in Step 7, the following algorithm is used (the one-dimensional array contains a variable "f", which is a vector list of numbers, and the term "f[n]" below refers to the nth number in "f").

[0042]

number

[0043] Referring now to Figure 4, which shows a region of the partially filled capillary image that has been masked by the logical OR of the two generated masks, with the selected portion of that region indicated in reddish color.

[0044] Figure 5 is a diagram / graph of the column-oriented one-dimensional array calculated in step 6, which is the sum of the column values ​​of the logical OR of the two generated masks. This plot is a horizontal function and shows how many pixels with the selected hue are in each column. The array sBWYH is then optionally subjected to erosion and dilation operations to reduce noise. 8) sBWYH = ndimage.grey_erosion(sBWYH,structure=np.ones((50,))) 9) sBWYH = 2 * ndimage.grey_dilation(sBWYH,structure=np.ones((50,)))

[0045] The array sBWYH is then passed to the function findThreshold, which finds the lateral positions of transition points greater than a predetermined threshold of 40. 10) locs = findThreshold(40, sBWYH)

[0046] The starting point of the blood flow within the capillary is blood starting position 80, and the ending point of the blood flow within the capillary is blood ending position 82. 11) bloodStart = min(locs) 12) bloodEnd = max(locs)

[0047] The filling percentage value is calculated by multiplying the difference between the blood start position 80 and the blood end position 82 by the calibration value (calVal). 13) pcntFill = (bloodEnd - bloodStart) x calVal

[0048] [Determination of Calibration Value (calVal)] The calibration value is predetermined using a reference capillary known to be 100% filled with blood or an alternative such as red dye or red epoxy. The image from this calibration / reference capillary is subjected to the same processing steps, except that step 13 is skipped and the calibration value is calculated using step 14 below. 14) calVal = 100.0 / (bloodEnd - bloodStart)

[0049] Calibration / reference capillaries can be filled with any substance exhibiting the desired red hue. A preferred formulation used consists of a mixture of 0.30 grams of UV-curable clear epoxy NOA81 and 0.06 grams of CongoRed dye powder SigmaC6277-25G (lot number MKCF4499, with a dye content of 95%). This mixture is pressed into the capillary using a syringe and needle until the capillary is 100% filled, and then cured using a UV curing lamp.

[0050] Figure 6 shows the filling percentage calculation, which is the result for a partially filled capillary. The vertical lines in this figure indicate the positions of the blood start point 80 and the blood end point 82.

[0051] Preferred embodiments of the present invention have been described herein, but the above description is merely illustrative. Further modifications of the present invention disclosed herein will be conceivable to those skilled in the art, and all such modifications will be considered to be within the scope of the invention as defined in the appended claims.

Claims

1. A system configured to measure the filling percentage of a blood collection capillary containing a blood sample, A chamber configured to receive the blood collection capillary containing the blood sample, A light fixture configured to illuminate the aforementioned blood collection capillary, The chamber and the blood collection capillary are aligned in a line with the imaging lens, An imaging sensor aligned in a line with the imaging lens, the imaging sensor being configured to receive an image of the blood sample contained in the blood collection capillary from the imaging lens and to convert the image of the blood sample contained in the blood collection capillary into image data. A microcontroller circuit electrically connected to the aforementioned imaging sensor, First image data is generated from the aforementioned image data, and the first image data is converted into a first image in a first type of hue space. A second image data is generated from the aforementioned image data, and the second image data is converted into a second image in a second type of hue space different from the first type of hue space. A first mask generated based on the first image in the first type of hue space and a second mask generated based on the second image in the second type of hue space are combined into a one-dimensional array. The filling percentage of the blood collection capillary containing the blood sample is determined by using predetermined calibration values ​​obtained by analyzing image data of a reference capillary having a known blood filling percentage, or a blood substitute having a red hue. The microcontroller circuit is configured as described above, The system is configured to transmit the filling percentage of the blood collection capillary containing the blood sample to at least one of a computer and a user interface. system.

2. The system according to claim 1, The illuminator is a system consisting of a light-emitting diode (LED) configured to emit white light.

3. The system according to claim 1, further, The imaging lens and the imaging sensor are arranged in a line with an aperture structure, The aperture structure is positioned between the imaging lens and the imaging sensor and is configured to reduce image distortion and aberrations caused by the imaging lens by narrowing the light ray cone of the image of the blood sample contained in the blood collection capillary. system.

4. The system according to claim 1, The system further comprises a microcontroller circuit configured to control the illuminator.

5. The system according to claim 1, The system further comprises a microcontroller circuit configured to select pixels from the image of the blood sample contained in the blood collection capillary whose pixel values ​​fall within a specific range of hue.

6. The system according to claim 1, A system in which at least one of the following is true: the first type of hue space is a YCbCr color space, and the second type of hue space is an HSV color space.

7. The system according to claim 1, A system in which the first type of hue space is a YCbCr color space, and the second type of hue space is an HSV color space.

8. The system according to claim 1, The known filling percentage is 100 percent in the system.

9. The system according to claim 1, A system further comprising the aforementioned standard capillary.

10. The system according to claim 1, The microcontroller circuit is configured to determine the filling percentage of the blood collection capillary containing the blood sample using the predetermined calibration value, (a) (i) the difference between the blood start position determined from the image of the blood sample contained in the blood collection capillary and (ii) the blood end position determined from the image of the blood sample contained in the blood collection capillary, (b) The system according to claim 1, configured to multiply by the predetermined calibration value.

11. The system according to claim 10, The aforementioned microcontroller circuit is A system further configured to determine the blood start position and the blood end position by finding the lateral position of one or more transitions greater than a predetermined threshold value that identifies the blood start position or the blood end position.

12. The system according to claim 1, The microcontroller circuit is further configured to perform at least one of the following: erosion on the one-dimensional array to reduce noise, and dilation on the one-dimensional array to reduce noise. system.

13. The system according to claim 1, The microcontroller circuit is further configured to perform both erosion on the one-dimensional array and dilation on the one-dimensional array to reduce noise. system.

14. The system according to claim 1, The microcontroller circuit is configured to combine the first mask and the second mask into the one-dimensional array, and is configured to sum the first mask and the second mask pixel by pixel. system.

15. The system according to claim 14, The microcontroller circuit is configured to sum the first mask and the second mask pixel by pixel, and is configured to sum the first mask and the second mask in the column direction into the one-dimensional array. system.

16. The system according to claim 1, The microcontroller circuit is further configured to generate the first mask and the second mask based on a selected hue range. The pixels within the selected hue range are set to 1 in the first mask and the second mask. The system according to claim 1, wherein pixels outside the selected hue range are set to 0 in the first mask and the second mask.

17. The system according to claim 1, The blood substitute system comprises at least one of a red dye or a red epoxy.

18. The system according to claim 1, The blood substitute system comprises an ultraviolet-curable epoxy and a red dye powder.

19. The system according to claim 1, A system further comprising at least one of the computer and the user interface.

20. In the system described in Claim 1, The microcontroller circuit is further configured to generate the first mask and the second mask based on a selected hue range, wherein pixels within the selected hue range are set to 1 in the first mask and the second mask, and pixels outside the selected hue range are set to 0 in the first mask and the second mask. The microcontroller circuit is configured to combine the first mask and the second mask into the one-dimensional array, and is configured to add the first mask and the second mask to the one-dimensional array in the column direction for each pixel. The microcontroller circuit is configured to determine the filling percentage of the blood collection capillary containing the blood sample using the predetermined calibration value, wherein (a) (i) the difference between the blood start position determined from the image of the blood sample contained in the blood collection capillary and (ii) the blood end position determined from the image of the blood sample contained in the blood collection capillary is multiplied by (b) the predetermined calibration value. The microcontroller circuit is further configured to determine the blood start position and the blood end position by finding the lateral position of one or more transitions greater than a predetermined threshold value that identifies the blood start position or the blood end position. system.

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