CA2222554C

CA2222554C - Method and apparatus for continuously monitoring and forecasting slide and specimen preparation for a biological specimen population

Info

Publication number: CA2222554C
Application number: CA002222554A
Authority: CA
Inventors: Shih-Jong J. Lee; Dayle G. Ellison; Paul S. Wilhelm
Original assignee: TriPath Imaging Inc
Current assignee: TriPath Imaging Inc
Priority date: 1995-05-31
Filing date: 1996-05-29
Publication date: 2002-11-19
Anticipated expiration: 2016-05-29
Also published as: CA2222554A1; WO1996038807A1; EP0829063A4; ES2121712T1; JPH11506196A; AU699884B2; DE829063T1; US5625706A; AU5881296A; JP3586695B2; EP0829063A1

Abstract

An automated laboratory process monitoring method (106) for a computer controlled automated cytology system initializes lab process assessment slid e data so as to produce an initial batch of qualified slides (110). Monitor parameters (114) are extracted from the initial batch of qualified slides (110) so as to determine control limits. Field data is monitored (106) by comparing the field data to the control limits (132).

Description

METHOD AND APPARATUS FOR CONTINUOUSLY MONITORING AND
FORECASTING SLIDE AND SPECIMEN PREPARATION FOR A
BIOLOGICAL SPECIMEN POPULATION
BACKGROUND OF THE INVENTION
This invention relates generally to automated cytological analysis systems and, more particularly, to a method and apparatus for continuous automatic monitoring and forecasting of slide and specimen preparation quality for biological specimen f-fixed and stained on glass slides.
Detection of disease processes is dependent on adequate specimen collection, proper fixation, staining and mounting of specimens on microscope slides. Laboratory preparation processes can vary over time because variations may occur in specimen collection, fixation, staining and mounting quality for a population of slide specimens. To ensure that slides and specimens are continuously prepared in a fashion which allows for the detection of disease processes, continuous monitoring and forecasting of slide and specimen preparation quality is required.
Standards for the practice of cervical/vaginal cytology have been suggested by the introduction of the well known Bethesda System. However, significant variations in cytological specimens such as, for example, specimens stained with the well known Papanicolaou stain ("pap smears") still occur.
Although the pap smear screening process can accommodate slide population, sampling, and preparation variations to some degree, variations that adversely affect the screener's ability to detect the disease process can occur. It is, therefore, important to develop a monitoring process to detect and forecast such variations in order to maintain adequate laboratory preparation for the detection of

- 2 -disease process.
Specimen preparation is monitored periodically by human visual -review. This solution has not been satisfactory~because the periodic monitoring process is subjective and could suffer from period to period and reviewer to reviewer inconsistency. Also, if a laboratory process is found unsatisfactory with periodic monitoring, it may not be possible or desirable to retrospectively re-process those slides processed during the unsatisfactory period. No alternative solution has been available prior to this invention.
It is one motivation of the invention to automate a process that is currently carried out using subjective manual processes. It is another motivation of the invention to improve the quality and consistency of smear and slide preparation for the detection of disease processes.
In contrast to the prior art, the present invention provides a method and apparatus wherein slides and specimens are examined in an automated biological specimen screener such as the AutoPap 300 System made by NeoPath, Inc. of Redmond, Washington, U.S.A. The, automated biological-specimen screener measures, among other things, parameters of specimen collection quality, fixation quality, staining quality and mounting quality. These measures are- objective and provide a consistent standard of evaluation.
Rather than monitor periodically, an automated biological specimen screener made in accordance with the present invention measures a consistently updated most recent set of slides as part of the monitoring process. Continuous monitoring of process parameters provides the means to administer a short term and mid- ' term process tracking mechanism. The short-term ' 77501- 7

-3-tracking mechanism reports recent (that is, relative to mid-term) variations in the laboratory process that can be adjusted before adverse screening conditions occur. It also allows the laboratory to track variation patterns, providing the means to forecast adverse conditions which can occur if the parameters of the mid-term tracking mechanism fall outside acceptable limits. For example, keyed by slides which are increasingly borderline acceptable for the detection of disease processes, short-term tracking allows a laboratory to immediately detect changes in nuclear staining. These changes suggest the need to adjust staining solutions. The staining parameters for the short term tracking can be used to adjust a staining process in an automated fashion, before staining quality becomes unacceptable.
SUMMARY OF THE INVENTION
An automated laboratory process monitoring method for a computer controlled automated cytology system initializes lab process assessment slide data so as to produce an initial batch of qualified slides. Monitor parameters are extracted from the initial batch of qualified slides so as to determine control limits. Field data is monitored by comparing t:he field data to the control limits.
The method and apparatus of the invention uses objective measures rather than subjective measures, monitors continuously rather than periodically, and provides a mechanism for forecasting slide and specimen preparation variations which result in inadequate specimen collection, proper fixation, staining and mounting of specimen before the qualities become unacceptable.

-3a-In accordance with the present invention, there is provided a laboratory process monitoring method for a laboratory that prepares slides, said method comprising the steps of: (a) acquiring an initial set of laboratory slides so as to select an initial batch of slides for initialization (102); (b) extracting an initial monitor parameter with an automated cytology system from said initial batch of slides (108) so as to determine a control limit (130); (c) monitoring field data by extracting said monitor parameter from said field data (108) with said automated cytology system; and (d) comparing said monitor parameter from said field data to said control limit (306) to monitor a slide preparation.
Other objects, features and advantages of the present invention will become apparent to those

- 4 -skilled in the art through the description of the preferred embodiment, claims and drawings herein wherein like numerals refer to like elements.
BRIEF DESCRIPTION OF THE DRAWINGS
To illustrate this invention, a preferred embodiment will be described herein with reference to the accompanying drawings. a Figures 1A, 1B and 1C show one embodiment of the invention.
Figure 2 shows a flow chart ofa method for assessing slide and specimen preparation quality.
Figures 3A, 3B, 3C, 3D and 3E are more detailed flow charts of a-method for assessing slide and specimen preparation quality.
Figure 4 shows a block diagram of one example of an initialization process for a laboratory process monitoring method and apparatus as employed in one embodiment of-the invention.
Figure 5 shows a flow diagram of one example of a laboratory process monitoring method and apparatus as employed in one embodiment of the invention.
Figure - 6 shows sub-categories of specimen collection monitoring parameters as employed in one embodiment of the invention.
Figure 7 shows categories of- preparation monitoring parameters as employed in one embodiment of the invention.
Figure 8 shows a process flow diagram of one example of an initialization module as employed in one embodiment ofthe invention.
Figure 9 shows a process flow diagram of one example of a field monitoring module as employed in one embodiment of the invention.
Figure 10 shows a block diagram of one example of ' an automated slide and specimen preparation modul-a as _5_ employed in one embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention provides a method for continuous monitoring and forecasting of a clinical laboratory's slide and specimen preparation quality for biological specimen. In a presently preferred embodiment of the invention, the invention is applied to use of the AutoPap 300 system, an automated Pap smear screener, in the laboratory setting.
The invention provides a set of procedures, herein called Laboratory Process Monitoring, that a clinical laboratory can use to monitor and forecast slide and specimen preparation quality for biological specimen fixed and stained on glass slides. Laboratory preparation processes may vary over time with variations in specimen collection, fixation, staining and mounting quality for a population of slide specimen. The Laboratory Process Monitoring procedures specifically measure, test, and provide short- and mid-term tracking capabilities to the laboratory for slide physical characteristics, specimen collection quality, slide handling quality and preparation quality. The short term tracking capability allows a laboratory to adjust process before adverse.conditions, which can lead to reduced detection of disease processes, occur.

7701-7~

Now refer to Figures 1A, 1B and 1C which show a schematic diagram of one embodiment of the apparatus of the invention 500. The apparatus of the invention comprises an imaging system 502, a motion control system 504, an image processing system 536, a central processing system 540, and a workstation 542. The imaging system 502 is comprised of an illuminator 508, imaging optics 510, a CCD camera 512, an illumination sensor 514 and an image capture and focus system 516. The image capture and focus system 516 provides video timing data to the CCD cameras 512, the CCD cameras 512 provide images comprising scan lines to the image capture and focus system 516. An illumination sensor intensity is provided to the image capture and focus system 516 where an illumination sensor 514 receives the sample of the image from the optics 510. In some embodiments optics 510 may comprise color filters. In one embodiment of the invention, the optics may further comprise an automated microscope 511. The illuminator 508 provides illumination of a slide. The image capture and focus system 516 provides data to a VME bus 538. The VME bus distributes the data to an image processing system 536. The image processing system _7_ 536 is comprised of field-of-view processors 568. The images are sent along the image bus 564 from the image capture and focus system 516. A central processor 540 controls the operation of the invention through the VME bus 538. In one embodiment the host CPU 562 comprises a MOTOROLA* 68030 CPU. The motion controller 504 is comprised of a tray handler 518, a microscope stage controller 520, a microscope tray controller 522, and a calibration slide 524.
The motor drivers 526 position the slide under the optics.
A bar code reader 528 reads a barcode located on the slide *Trade-mark 7701-~
_g_ 524. A touch sensor 530 determines whether a slide is under the microscope objectives, and a door interlock 532 prevents operation in case the doors are open. Motion controller 534 controls the motor drivers 526 in _ g _ running a real time operating system, controls the microscope 511 and the processor to acquire and digitize images from the microscope 511. The flatness of the slide may be checked, for example, by contacting the four corners of the slide using a computer controlled touch sensor. The computer 540 also controls the microscope 511 stage to position the specimen under the microscope objective, and from one to fifteen field of view (FOV) processors 568 which receive images under control of the computer 540.
It is to be understood that the various processes described herein may be implemented in software suitable for running on a digital processor. The software may be embedded, for example, in the central processor 540.
Laboratory Process Assessment Slide Data Refer now to Figure 2 which shows a process flow diagram of a method for assessing slide and specimen preparation quality in accordance with the laboratory process assessment of - slides employed in the invention. A technician gathers a set of laboratory slides with representative normal and abnormal slides in step 10. The slides may all be from a laboratory chosen to be evaluated. In the preferred embodiment, the assessor acquires 400 slides from the laboratory.
The slide set consists of the following slides:
200 within normal limit slides, 150 low grade SIL slides, and 50 high grade SIL slides.
Low grade squamous intraephithelial lesions (LSIL) and high grade SIL (HSIL) are low grade and high grade squamous intraephithelial lesions. These lesions are the extremes of a spectrum of lesions which may include noninvasive cervical epithelial abnormalities traditionally classified as flat condyloma, dysplasia/carcinoma in-situ, and cervical intraepithelial neoplasia.
An automated system, such as, for example, is described in the referenced patents;- processes the slide set to_obtain data for assessing slide and specimen preparation quality in step 20. In one preferred embodiment, the automated system may comprise theAutoPap~ 300, available from NeoPath, Inc. Slides are stained and coverslips are applied.
The automated system processes and obtains data from the acquired slides.
During processing of a slide by the automated system, a slide's processing results may fall outside established _processing limits. Slide processing failures for which successful setup is not attained, are referred to as slide scanning or set-up failures.
Some slides may be set up successfully during processing but have other characteristics such as certain preparation related characteristics, that prevent successful processing by the automated system.
Processing failures. may thereby result. Such failures are referred to as process suitability failures.
In steps 30-70, the automated system performs a series oftests on the data obtained in step 20. In step 30, the automated system performs a Slide Physical Characteristics Test to evaluates the physical characteristics of Pap Smear slides to determine if they may be successfully set up and scanned by a predetermined automated biological specimen analyzer, such as the AutoPap° 300 System.
The Slide Physical Characteristics Test evaluates the physical characteristics of the slides acquired from the laboratory. These physical characteristics may include, for -example, the characteristics shown in Table 1.

Table 1 Slide too thick Unable to map coverslip surface Coverslip edges not detected Coverslip length not 40, 50, or 60 mm Coverslip width not with limits Coverslip corners not square Coverslipped area too small Coverslip skewed on slide Unable to focus on specimen Coverslip and specimen too thin Coverslip and specimen too thick During evaluation, the automated system discontinues processing for slides that fall outside of an acceptable range for any of the preselected criteria. The automated system may count a proportion of slides failing processing. In one preferred embodiment,.the slide set is considered to pass if the proportion of slides failing processing is less than 60; otherwise the slide set fails.
In step 40, the automated system performs a Specimen Collection Quality Test to evaluate the quality and sufficiency of the specimen material sampled on the slide. Specimen collection quality is highly dependent upon a clinic's sampling tools and techniques for specimen collection. In the preferred embodiment, the Specimen Collection Quality Test may comprise two tests. Tables 2 and 3list qualities for which the slide set may be tested. Slides failing these tests comprise the specimen collection quality failures. Table 2 tabulates slide set-up related failures- Table 3 tabulates failures related to process suitability failures. Process- suitability failures may include, for-example, slides that are set up successfully but for which process results cannot be expected to be reliable, for example., when the process detect too few reference cells. The proportion of slides failing processing for these reasons is measured- In the preferred embodiment, if the proportion of slides that failed the first test is less than 70, the slide set is considered to pass the first test; otherwise, the slide set fails.
Iri the preferred embodiment, the second specimen quality test measures and ranks the reference cell ratio for all normal slides that are successfully processed. The reference cell ratio is the number of detected reference cells ('that is, free-lying intermediate -cells) on a slide divided by the number of all objects detected on the slide. In one preferred embodiment, if 85a of the normal slides have a reference cell ratio greater than 0.015, then the slide set is considered to pass the test; otherwise, the slide set fails.
The slide set is required to pass both specimen quality tests to-pass the Specimen Collection Quality Test.

Table 2 Lack of material in center Too. few points for low-power focus map Specimen distributed in small area Unable to focus on specimen Specimen tilt Too few fields ranked in low-power scan Too few points for high-power-focus map High-power focus surface too variable Too few focused fields in high-power scan Table 3 Insufficient-reference cells Image quality not within limits, percentage of fields focused on first try.
Image quality not within limits, percentage of fields never focused .
The automated system performs a Slide Handling Quality Test in step 50. The Slide Handling Quality Test determines if slide handling practices may need to be modified to facilitate effective processing on a selected automated system, such as the AutoPap° 300 System. The test evaluates the quality of slide barcoding, cleaning, and loading practices at a preselected clinical site. Tables 4 and 5 list tests for slide handling quality failures. Table 4 tabulates slide set-up related failures. Table 5 tabulates failures related to process suitability failures_ The system measures the proportion of slides failing these tests. In the preferred embodiment, if the proportion of slides that failed is less than 50, the slide set is considered to pass the slide handling quality test; otherwise, the slide set fails .
Table 4 Slide barcode not read Slide tilted Table 5 Image quality not withinlimits, excessive striping.

Image quality not withinlimits, high power magnificationimage saturation (small amounts) Image quality not withinlimits, high power magnificationimage saturation (large amounts) Image quality not withinlimits, low power-magnification image saturation.

The automated system performs a Preparation Quality Test in step 60. The Preparation Quality Test evaluates the result of laboratory fixation, staining, and coverslipping processes todetermine whether the presentation of cells is within an acceptable range.
In the preferred embodiment, five tests comprise preparation quality test - to pass the full test, the slide set must pass all tests. Referring to Tables 6 and 7, slides which fail processing for the tabulated reasons comprise the preparation quality failures.
The proportion of slides failing processing for these ' reasons is measured_ Table 6 tabulates slide set-up related failures. Table 7 tabulates failures related ' to process suitability failures. In the preferred WO 96/38807 PCTIi1S96/07830 embodiment, if the proportion of slides that failed the first test is less than 50, the slide set passes the first test; otherwise, the slide set fails.
Table 6 Too many bubbles Too few fields ranked in low-power scan Table 7 Stain average not within limits Cytoplasm Staining not within limits Staining detail not within limits Nuclear/Cytoplasm contrast not within limits Insufficient reference cells Image quality not within limits, high power magnification image saturation (large amounts) Image quality not within limits, low power magnification image saturation.

In the preferred embodiment, the second preparation quality test measures the nuclear stain density of the reference cells detected on the normal, successfully processed, slides. Measurements are stored in a "mean stain" bin. The mean optical density for each detected intermediate cell nucleus is calculated. Data for all the detected intermediate cell nuclei on the slide is accumulated in a 10-bin histogram. The average staining score for the normal ~ slides is calculated. In the preferred embodiment, if the average staining score is greater than 4.2 and less than 6.4, the slide set passes the test;
otherwise, the slide set fails.
~ In the preferred embodiment, the third '7701-T

preparation quality test counts the number of potentially abnormal cell nuclei detected on slides that process successfully (stage 3 abnormals). The 80th percentile of the normal slides which contain endocervical component cells is calculated. In the preferred embodiment, if the gpth percentile is greater than 3, the slide set passes the test;
otherwise, the slide set fails.
In the preferred embodiment, the fourth preparation quality test measures the 80th percentile of the QC score of successfully processed normal slides that contain endocervical component cells. In the preferred embodiment, if the 80th percentile is greater than 0.15 and less than 0.6, the slide set passes the test; otherwise, the slide set fails.
In the preferred embodiment, the fifth preparation quality test measures the median of reference cell nuclear texture (nuclear blur average) for successfully processed normal slides which contain endocervical component cells.
In the preferred embodiment, if the median is greater than

5.65, the slide set passes the test; otherwise, the slide set fails.
In step 70, the automated system performs a Classification Test. The Classification Test evaluates whether the customer slide and cell presentation are within the training range of the AutoPap° 300 System to enable an effective interpretation by the system. The test evaluates the accuracy of slide classifications for slides that are successfully processed.
The system accuracy test evaluates sensitivity to abnormal specimen morphology. The 80th percentile of the QC
score of the normal slides is calculated. In the preferred embodiment, if more than 70~ of the low grade slides and 800 of the high grade slides have QC scores above the 80th percentile for normal slides, the slide set passes the test; otherwise, the slide set fails.
In step 80, the automated system then integrates the results from the tests in steps 30-70. In some aspects of the invention, the tests may be weighted. For example, tests that affect accuracy may be given greater weight than tests that affect yield. For example, the physical character-istic test relates to yield rather than accuracy and would be given less weight. In the preferred embodiment, the slide set must pass each test or the slide set is considered to fail.
If the slide set passes, the test result integration states that the slide set is acceptable in step 90. If the slide set fails, the test result integration makes recommendations for adjustment of the laboratory or clinic process in step 100.
Now referring jointly to Figures 3A, 3B, 3C, 3D
and 3E, Figure 3A shows a more detailed flow chart of a 2.0 method for assessing slide and specimen preparation quality.
In one embodiment of the invention, slides are collected at step 1102. At process step ll04 the collected slides are cleaned and a barcode is affixed to the slides. At process step 1106 the slides are processed in accordance with the various quality control methods described herein. Processing includes process steps 1108 through process step 1168 as shown in Figures 3A-3E and as described with reference to the tables hereinbelow. As best shown in Figure 3B, process step 1108 comprises process steps 1128, 1130. At process step 1128 a 30 percentage of slides is determined as failing quality control processing for physical characteristics. At process step 1130 slides are determined to be unacceptable as failing quality control processing for physical characteristics if more than 60 of the slides failed this test.
Referring now to Figure 3C, a more detailed flow diagram of process step 1110 is shown. At process step 1132 a percentage of slides isdetermined as failing quality control processing for specimen collection characteristics. At process step 1134 reference cell ratios are ranked for all normal slides. At process step 1136 slides are determined to be unacceptable as failing quality control,processing for specimen collection characteristics if more than 7% of the slides failed the specimen collectiontest.
At process step 1138, slides are determined to be unacceptable if 850 of the slides have a reference cell ratio > 0.15.-Referring now to Figure 3D, a more detailed flow diagram of process step 1112 is shown. At process step 1140 a percentage of slides is determined as failing quality control processing for slide handling quality characteristics. At process step 1142 slides are determined to be unacceptable as failing quality control processing for slide handling quality characteristics if more than 50 of the slides failed this test.
Referring now to Figure 3E, a more detailed flow diagram of process step 1114 is shown. At process step 1150 a percentage of slides is determined as failing quality control processing for specimen preparation characteristics. At process step 1152 nuclear stain density of-reference cells detected on slides is measured. At process step 1154 potentially ' abnormal cell nuclei on each slide are counted. At process step 1156 the 80th percentile of QC scores of normal slides with endocervical component is measured_ At process step 1158 the median of reference cell nuclear texture for normal slides with endocervical component is measured. At process step 1160 slides are determined to be unacceptable as failing quality control processing for specimen quality characteristics if more than 5~ of the slides failed this test. At process step 1162 the average staining score is checked. If the average staining score is less than 4.2 or greater than 6.4, the slides are deemed unacceptable for specimen preparation quality characteristics.
At process step 1164, if the 80th percentile is less than 3, then the slides are not acceptable for specimen preparation quality characteristics. At process step 1166, if the 80th percentile is less than .15 or greater than 0.6, then the slides are not acceptable for specimen preparation quality characteristics. At process step 1168, if the median of reference cell nuclear texture for normal slides witr~ an endocervical component is less than or equal to 5.65, then the slides are not acceptable for specimen preparation quality characteristics.
Referring again to Figure 3A, at process step 1116, a percentage of abnormal slides is determined as scoring higher than the 80th percentile of normal specimens. At process step 1126 slides are determined to be not acceptable if fewer than 700 of the low grade slides or fewer than 80%
of the high grade slides have scores higher than the 80th percentile of normal specimens.
Laboratory Process Monitoring Components Referring now to Figure 4, Figure 4 shows a block diagram of one example of an initialization process for a laboratory process monitoring method and apparatus as employed in one embodiment of the invention. In a preferred embodiment of implementation, the initialization process comprises an initialization module 104, a field monitoring module 106 and a monitoring parameter extraction module 108.
S The initialization module 104 uses the lab process assessment slide data 102 acquired during the laboratory process assessment (LPA) to form an initial batch and characterization batch of slides. The monitoring parameter extraction module extracts the initial parameters, which determine the control limits of the monitoring parameters.
Initialization Referring now to Figure 8, Figure 8 shows a process flow diagram °of one example of an initialization module 104 as employed in one embodiment of the invention. The initialization module 104 comprises a plurality of stages including a slide qualification- criteria determination stage 120, an initial batch formation stage 124, and a control limits determination stage 130.
During Initialization, slide qualification criteria 120 are defined using the lab process assessment slide data 102 from the LPA. These criteria are then used to qualify slides and form the ' initial slide batch and characterization slide batch at process flow branch 126. Initial monitoring parameters 114A are extracted-from-the initial slide batch and characterization slide batch. Finally, the initial monitoring parameters 114A may be processed by the control limits determination stage 130 to define control limits 132 for monitoring the parameters.
Slide Qualification Criteria Determination ' To ensure that the laboratory process assessment slides are-representative of a particular laboratory's slide population, criteria may be established to qualify slides. At least two sets of criteria may be used for qualification including reduced process suitability limits and a global Qc score upper-bound for slides that are successfully processed.
The reduced process suitability limits may be generated by adjusting the limits of the features used in suitability tests that determine the reliability of other slide scores. The adjustment is applied only to feature limits that are not exceeded by the feature values of the Laboratory Process Assessment slide data 102. Adjusted limits may be defined as the average of the original limit and the closest feature value of the LPA slide data 102.
The global Qc score upper bound may advantageously be determined using all the successfully processed normal slides in the Laboratory Process Assessment set . The slides are ranked by their Qc scores, and the Qc score value corresponding to the 90 o quantile of the ranked distribution defines the global Qc score upper bound.
Initial Batch and Characterization Batch Formation The initial batch for the AutoPap 300 System includes all normal slides in the Laboratory Process Assessment set. The initial batch further comprises a 3o random sample of the Ls=L slides and a 4o random sample of the HszL slides in the Laboratory Process Assessment set. Some monitoring parameters such as certain slide physical characteristic parameters are derived from the initial batch.
A preliminary characterization batch is formed from the initial batch by including only the slides ' that are successfully processed and have features within the reduced process suitability limits and Qc scores less than or equal to the global Qc score upper bound. A characterization batch is formed by excluding the slides that have Qc scores in the top and bottom l00 of the preliminary characterization slide batch. Some monitoring parameters, such as certain preparation parameters, are derived from the characterization batch.
Monitoring Parameter Extraction During the initialization process, the monitoring parameter extraction module 108 extracts initial parameters that define the control limits 132,for the monitoring parameters. During the field. monitoring process, the monitoring parameter extraction module 108 extracts monitoring parameters 114 from updated slide batches. Initial slide and characterization batches determine the initial monitoring parameters, which determine the initial control limits. The monitoring parameters 114 extracted from updated batches, falling within or outside the control limits 132, determine the compatibility of laboratory processes. Certain monitoring parameters, such as preparation monitoring parameters,- are used to adjust or maintain staining and coverslipping processes.
The parameters used to monitor laboratory processes include slide physical characteristics parameters, specimen collection monitoring parameters, slide handling monitoring parameters, and preparation monitoring parameters.
Note that the reduced process suitability limits rather than the original process suitability limits are used for parameters, such as preparation monitoring parameters, throughout the,. parameter extraction.process.
Slide Physical Characteristics Parameters The slide physical characteristics,parameters monitor the physical characteristics of the slides ' processed by a laboratory. The slide physical characteristics parameters fall into general categories including -o slide characteristics, o coverslip dimensional characteristics, and o- combined coverslip and specimen characteristics.
Slides in a given batch are tested using set up or scanning failure conditions for each slide physical characteristics category.
Toderive the slide physical characteristics parameters, the proportions of slides in a given batch that fail any of the tests are measured_ The following proportions are output as slide physical characteristics parameters:
P slide Slidecharacteristics failure proportion, P cover Coverslip dimensional characteristics failure proportion, P cover/spec Coverslip/specimen characteristics failure proportion, and P physical Overall slide physical characteristics failure proportion, where P_p.hysical = P slide + P cover + P cover/spec.
Specimen Collection Monitoring Parameters The specimen collection monitoring parameters 202 monitor the quality and sufficiency of the material of the collected cervical specimen for a given batch. As shown in Figure 6, the specimen collection monitoring parameters 202 fall into categories including material monitoring parameters 204 and reference cell characteristics 206. The material monitoring parameters 204 further comprise a scanty material distribution parameter 208 and a variable material distribution parameter 210.
Material Monitoring Parameters Slides in a given batch of slides are tested CA 02222554 1997-11-27 jT,~y~_. ' . .-. . .. . , . _ " ~ _ . -. q ., .. J
- 2 4.- -using set up, scanning and process suitability failure conditions for each material monitoring parameter -category. .The proportions of slides in the batch failing any of the material quality tests are measured as the material monitoring parameters.
Reference Cell Characteristics Parameter The reference cell parameter is the 85o quantile of the number of reference 'cells divided by all detected objects derived from all the characterization-batch slides in the given slide batch.
Output Parameters The following measurements are output as specimen collection monitoring parameters:
P scanty scanty material distribution failure proportion, P variable variable material distribution failure proportion, P material overall material quality failure proportion, and P reference reference cell characteristics parameter, where P material = P scanty + P variable.
Slide Handling Monitoring Parameters -The slide handling monitoring parameters monitor the quality of a customer's slide handling practices.
The slide handling monitoring parameters fall into general categories including o barcode error, o positioning error, and o cleaning error.
.C.'~ =rjcc = __ _ --._. ~ '..1-tr~n ~~+-r.l, arc toc~a~ '.:~ ='_~~ ~~3nr.
=,~r7 and process suitability failure conditions for each slide handling quality category. To derive the 35- parameters, the proportions of slides in a given batch CA 02222554 1997-11-27 ~~ ~~~J l '~~ J °'' IPEI~Jt~~ I ~ (~~ G ~~~o that fail any of the tests are measured. The following proportions are output as slide handling monitoring parameters:
P barcode barcode error failure proportion, P position positioning error failure proportion, P cl-can cleaning error failure proportion, and P handling overall slide handling quality failure proportion, where P handling = P harcode + Prposition + P clean.
Slide Preparation Monitoring Parameters The slide preparation monitoring parameters monitor the quality of a laboratory's fixation, staining, and coverslip application processes. As shown in Figure 7, the preparation monitoring parameters may advantageously comprise:
o bubble adequacy 222, o mount-ing medium adequacy 226, o staining adequacy 224, and o additional adequacy 238.
In addition, the staining adequacy 224 and additional adequacy 238 categories contain subcategories of parameters. Staining adequacy 224 may further include light stain adequacy 228, nuclear stain adequacy 230, cytoplasm stain adequacy 232, chromatin adequacy 234, and N/C contrast adequacy 236.
Additional adequacy 238 may further include staining score adequacy 240, stage3 alarms 242, QC score 244, and chromatin details 246. The categories are defined in more detail below.
Bubble. Staining, and Mounting Medium Adequacy Parameters Slides in a given batch are tested using scanning and process failure conditions for each category. The proportions of slides in a given slide batch failing one or more of the preparation quality tests are measured as preparation monitoring parameters.

Additional Adequacy Parameters Staining Score 240 - This parameter measures the average staining score for slides from the characterization b atch of a given slide batch.

Mean stain bin is the feature used for this measurement.

Stage 3 Alarm 242 ---This parameter measures the 80o quantile of the number of stage 3 alarms~from all characterization-batch slides in a given slide batch.

QC Score 244 - This parameter measures the maximum Qc score of all characterization-batch slides in a given slide ba tch.

Population beyond Global QC Score Upper Bound 248 - This parameter measures the percentage of slides in a given slide batch having the Qc score values greater than the global Qc score upper bound ( see Global QC

Score Upper Bound, described previously). Only the slides within the scanning and reduced process suitability limits are measured.

Chromatin Deta ils 246 - This parameter measures the median value of nuclear texture (nuclear blur avg) for all characterization-batch slides in a given slide batch.

Output Parameters The following measurements are output as slide preparation monitor ing parameters:

P bubble bubble adequacy failure proportion, P medium mounting medium failure _ proportion, P-light-stain light stain failure-proportion, P nuc stain nuclear stain failure proportion, P cyto stain cytoplasm sta-in failure proportion, P chromatin chromatin adequacy failure proportion, P N/C cntst N/C contrast adequacy failure proportion, P staining overall staining adequacy failure S proportion, P preparation combined bubble, mounting medium, and staining adequacy failure proportions, P SS staining score parameter, P alarm3 stage 3 alarm parameter, P QC c2c score parameter, P global population beyond global Qc score upper bound, and P detail chromatin details parameter, where P staining = P light stain + P nuc stain +
P cyto stain + P chromatin + P N/ C cntst.
Prpreparation - P bubble + P medium +
P staining.
Field Monitoring Referring now to Figure S, Figure 5 shows a flow diagram of one example of a laboratory process monitoring method and apparatus as employed in one embodiment of the invention. An automated slide and specimen preparation module 112 controls the coverslip application and staining processes for new slides 110 using conventionally available automated instruments.
Slides are considered to be new slides if they have not been previously assessed. The protocols for coverslip application and staining slide specimens used during the preparation of slides for the LPA
determine the processes for applying caverslips and staining slide specimens for initial process monitoring. As field monitoring data becomes available, control rule results for preparation monitoring parameters are used to automatically '77501-T

maintain or adjust the processes for applying coverslips to slides and staining of slides.
The field monitoring module 106 dynamically updates a set of slide batches 116 and, using the monitoring parameter extraction module 108, the monitoring parameters are also dynamically updated. A plurality of extracted parameters 114 are compared with control limits to determine the integrity of the laboratory slide population and preparation processes.
The control rule results for preparation parameters are used to automatically adjust slide and specimen preparation processes such as processes for using coverslips and staining.
Referring now to Figure 9, there shown is a process flow diagram of one example of a field monitoring module 106 as employed in one embodiment of the invention.
The field monitoring module 106 may comprise two main stages in one example of the invention including a slide batches update stage 304 and a control limits determination stage.
During field monitoring, newly processed laboratory slide data 302 are used in the slide batches update stage 304 to update slide batches. The monitoring parameter extraction module 108 extracts parameters from the updated slide batches. The parameters 114 are used for the application of the control rules at control rule application stage 306. The control rule results and the logged monitoring parameters 118 are output to a product/service database and user interface module 310 so that the data can be displayed or printed in any suitable manner. Control rule results for certain preparation related parameters adjust and maintain staining and coverslip applying processes.

Slide Batches Update During the field monitoring process, at least two batches may be continuously formed and updated including a 'short-term batch and a mid-term batch.
The short-term batch includes up to 300 of the most recently processed laboratory slides. The mid-term batch is a superset of the mid-term batch and comprises up to 1,000 of the most recently processed slides. If the number of slides in a batch exceeds the batch limit, the oldest slides in the batch are removed to maintain the batch size to the upper limit .
The short-term batch is used to indicate recent (relative to the mid-term batch) variations in the laboratory process that can possibly be adjusted before causing sever-a process-related problems. The mid-term batch is used to apply the control rules. A
laboratory process is considered "out of range" if the values of the monitor-ing parameters for the mid-term batch are outside of the control limits.
Monitoring Parameter Update After the short-term and mid-term batches are updated, the short-term and mid-term batches are formed according to the rules specified in reference to the initialization module as described with reference to Figure 9. The monitoring parameter extraction module 108 uses updated batches to extract the monitoring parameters.
Control Rule Applications This section describes the control rules developed for the following monitoring parameters:
o slide physical characteristics parameters, o specimen collection monitoring parameters, o slide handling monitoring parameters, and o preparation monitoring parameters.
The rules apply to only the slides in the mid-term batch. The laboratory process is considered "out of range" if any parameter falls outside the limits defined in the rules.
Slide Physical Characteristics Parameters P physical An upper limit ~is established for the overall slide physical characteristics failure proportion, Prphysical. The upper limit is defined- as:-P physical Upper Limit - MAXI 10e, 2*initial proportion of P_physical) where the initial proportion of P-physical is determinedduring the initialization stage based on the initial batch. If the,P_physical of the mid-term batch is greater than the upper limit, the laboratory fails this monitoring test. The other parameters derived from slide physical characteristics such as P slide, P cover, and P cover/spec are available as supporting evidence. They do not directly participate inthe test.
Specimen Collection Monitoring parameters P_material An upper limit is established for the- overall material quality failure proportion, P material. The upper limit is defined as:
P material. Upper Limit - MAX( 10%, 2*initial proportion of- P material) where the initial proportion of P material is determined during the initialization stage based on the initial batch. If the P material of the mid-term batch is greater than the upper limit, the laboratory fails this monitoring test.
P_reference In addition, a lower limit is established for the °
reference cell characteristics parameter, P reference.
The lower limit is defined as: -- ' P- reference Lower Limit = MAX ( 0 . 01 , initial proportion of P reference /2 ) where the initial proportion of P r-eference is determined during the initialization stage based on the initial batch. If the P reference of the mid term batch is less than the lower- limit, the laboratory fails this monitoring test. The other two specimen collection monitoring parameters: P scanty and P variable are available as supporting evidence.
They do not directly participate in the test.
Slide Handling Monitoring parameters P handling An upper limit is established for the overall slide handling quality failure proportion, P handling.
The upper limit is defined as:
P handling Upper Limit = MAX ( 8 0 , 2*initial proportion of P handling) where the initial proportion of P handling is determined during the initialization stage based on the initial batch. If the P handling of the-mid-term batch is greater than the upper limit, the laboratory fails this monitoring test. The other three slide handling monitoring parameters : P barcode, P-posi Lion, and P clean are available as supporting evidence.
They do not directly participate in the test.
Preparation Monitoring parameters P preparation An upper limit is established for the combined bubble, mounting medium, and staining adequacy failure proportion, P-preparation. The upper limit is defined as:
P preparation Upper Limit - MAX( 8a, 2*initial proportion of P preparation) where the initial pr-oportion of Preparation is determined during the initialization stage based on the initial batch. If the Preparation of the mid-term batch is greater than the upper limit, the laboratory fails this monitoring test.
P SS
Iri-addition, two limits are established for the staining score parameter, P SS. The lower limit is defined as P SS Lower Limit = MAX(4.0, initial P SS * 0.85) The upper limit is defined as:
P SS Upper Limit = MIN(6.6, initial P SS * 1.15) where the initial stain, P SS, is determined during the initialization stage based on the initial batch.
If the P SS of the mid-term batch is less than the lower limit or greater than the upper limit, the laboratory fails this monitoring test.
P alarm3 A lower limit is established for the stage'3 alarm parameter, P alarm3. The lower limit is defined as:
P alarm3 Lower Limit - MAX(3.0, initial P alarm3 0.7) where the initial P alarm3 is determined during the initialization stage based on the initial batch. If the P alarm3 of the mid-term batch is less than the lower limit, the laboratory fails this monitoring test.
P_QC
Two limits are established for the Qc score parameter, P QC. Tha lower limit is defined as:
P QC Lower Limit = MAX(0.15, initial P QC * 0.75) The upper limit is defined as:
P_QC Upper Limit = MIN(0.6, initial P QC * 1.25) ' where the initial P QC is determined during the initialization stage based on the initial batch. . If ' the P QC of the mid-term batch is less than the lower limit or greater than the upper limit, the-laboratory fails this monitoring test.
P_detail A lower'limit is established for the chromatin details parameter, P detail. The upper limit is defined as:
P detail Lower Limit - MAX ( 5 _ 5 , initial P detail 0.8) where the initial proportion of P detail is determined during the initialization stage based on the initial batch. If- the P_detail of the mid-term batch is less than the lower limit, the laboratory fails this monitoring test.
P_global Lastly, two limits are established for the population beyond global Qc score upper bound parameter, P global. The lower limit is defined as:
P global Lower Limit = 40 and the upper limit is defined as:
P global Upper Limit = 200 If the P_global of the mid-term batch is less than the lower limit or greater than the upper limit, the laboratory fails this monitoring test. The other preparation monitoring parameters, P bubble, P medium, P_light_stain, P_nuc_stain, P cyto stain, P chromatin, P_N/C_cntst, and P staining are available as supporting evidence_ They do not directly participate in the test.
Referring now to Figure 10, a block diagram of the automated slide and specimen preparation module as embodied -in one example of the invention is there shown_ The automated slide and specimen preparation module comprises an automated stainer application 402, an automated staining adjustment 404, an automated coverslip application 408 and an automated coverslip adjustment 410.
In operation, unstained slides without coverslips, here designated new slides 414, are input into the automated stainer application stage 402. In the automated stainer application stage 402 the protocol used during preparation of the LPA slide set determines the initial staining process used by the automated instrument. As field monitoring preparation parameters become available, the staining process is maintained or adjusted in an automated fashion using input obtained from the automated staining adjustment module.
In a similar fashion, staining processes may be adjusted at the automated staining adjustment stage 404- using control rules 406 derived from the data from preparation monitoring stain parameters. The adjustments are automatically applied to the automated stainer application 402.
Stained slides without coverslips are input into the automated coverslip application stage. The protocol used during preparation of the LPA slide set determines the initial coverslip application process for laboratory process monitoring. As field monitoring output becomes available, the coverslip application process is automatically maintained or adjusted using input obtained from the automated coverslip adjustment module.
In a similar fashion, coverslip application processes may be adjusted at the automated c-overslip adjustment stage 410 responsive to control rules 412 derived from the data from preparation monitoring bubble parameters and mounting medium parameters. The ' adjustments are automatically applied to the automated stainer application.
The invention has been described herein in considerable detail in order to comply with the Patent Statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment details and operating procedures, can be accomplished without departing from the scope of the invention itself.
What is claimed is:

Claims

1. A laboratory process monitoring method for a laboratory that prepares slides, said method comprising the steps of:
(a) acquiring an initial set of laboratory slides so as to select an initial batch of slides for initialization (102);
(b) extracting an initial monitor parameter with an automated cytology system from said initial batch of slides (108) so as to determine a control limit (130);
(c) monitoring field data by extracting said monitor parameter from said field data (108) with said automated cytology system; and (d) comparing said monitor parameter from said field data to said control limit (306) to monitor a slide preparation.

2. The laboratory process monitoring method of claim 1 further comprising the step of controlling coverslip application (408) wherein protocols for coverslip application processes are responsive (410) to said monitor parameter (412).

3. The laboratory process monitoring method of claim 1 further comprising the step of controlling staining processes (402) wherein protocols for staining application processes are responsive (404) to said monitor parameter (406).

4. The laboratory process monitoring method of claim 2 further comprising the stems of:
(a) acquiring field monitoring data (302, 304);
and (b) applying control rule results (118) for at least one slide preparation monitor parameter to automatically regulate coverslip application (408).

5. The laboratory process monitoring method of claim 3 further comprising the steps of:
(a) acquiring field monitoring data (302, 304);
and (b) applying control rule results (118) for at least one slide preparation monitor parameter to automatically regulate staining of slides (402).

6. The laboratory process monitoring method of claim 1 wherein the step of monitoring field data further comprises the steps of:
(a) dynamically updating a set of slide batches (110);
(b) dynamically updating said monitor parameter (108) using the updated slide batches (116) to produce an updated monitor parameter (108); and (c) comparing said updated monitor parameter (114) with said control limit (132) to determine integrity of a laboratory slide population and at least one preparation process (118).

7. The laboratory process monitoring method of claim 6 further comprising the step of ruling a laboratory process out of range if said monitor parameter falls outside of said control limit (118).

8. The laboratory process monitoring method of claim 1 wherein the step of acquiring an initial set of laboratory slides further comprises the steps of:
(a) determining slide qualification criteria (120, 122) using the initial set of laboratory slides (102);
(b) selecting an initial batch of slides (124, 126) using said initial set (102);
(c) forming a characterization batch using said initial batch of slides (124, 126) using said slide qualification criteria; and (d) determining said control limit (130, 132) by extracting said initial monitor parameter (108, 114A) from the initial batch of slides (126) or characterization batch.

9. The laboratory process monitoring method of claim 8 wherein the step of determining slide qualification criteria further comprises the steps of:
(a) applying reduced process suitability limits;
and (b) applying a global analysis score upper bound (248).

10. The laboratory process monitoring method of claim 1 wherein the step of extracting an initial monitor parameter (108) further comprises the step of extracting at least one slide physical characteristics parameter (1108) for monitoring physical characteristics of slides.

11. The laboratory process monitoring method of claim 10 wherein the at least one slide physical characteristics parameter (220) is selected from the group consisting of a slide characteristics category, coverslip dimensional characteristics category, and combined coverslip and specimen characteristics category (1108, 1110).

12. ~The laboratory process monitoring method of claim 10 wherein the step of extracting an initial monitor parameter (108) further comprises the step of testing slides in a given batch by scanning failure conditions for each slide physical characteristics category (1108).

13. The laboratory process monitoring method of claim 12 wherein the step of testing slides in a given batch by scanning failure conditions (1108) further comprises the steps of:
(a) measuring the proportions of slides that fail any scanning failure conditions (1128); and (b) outputting at least one proportion as a slide physical characteristics parameter (1108), wherein the at least one proportion is selected from the group consisting of slide characteristics failure proportion, coverslip dimensional characteristics failure proportion, coverslip/specimen characteristics failure proportion, and overall slide physical characteristics failure proportion.

14. The laboratory process monitoring method of claim 1 wherein the step of extracting an initial monitor parameter (108) further comprises the step of extracting at least one specimen collection monitoring parameter (202) for monitoring quality or sufficiency of a collected specimen.

15. The laboratory process monitoring method of claim 14 wherein the at least one specimen collection monitoring parameter (202) is selected from the group consisting of a material monitoring parameters (204) category and reference cell characteristics category (206).

16. The laboratory process monitoring method of claim 15 wherein said material monitoring parameters (204) category is selected from the group consisting of a scanty material distribution parameter (208) and a variable material distribution parameter (210).

17. The laboratory process monitoring method of claim 15 wherein the reference cell characteristics category (206) further comprises a predetermined percentage of the number of reference cells divided by all detected objects.

18. The laboratory process monitoring method of claim 1 wherein the step of extracting an initial monitor parameter (108) further comprises the step of extracting at least one slide handling monitoring parameter (1112) for monitoring quality of a laboratory's slide handling practices.

19. The laboratory process monitoring method of claim 18 wherein the at least one slide handling monitoring parameter (1112) is selected from the group consisting of a barcode error category, a positioning error parameter category, and a cleaning error parameter category.

20. The laboratory process monitoring method of claim0 19 wherein the step of extracting at least one slide handling monitoring parameter (1112) further comprises the steps of:
(a) testing at least one slide handling quality category by measuring the proportions of slides in a given batch that fail any scanning failure conditions or process suitability conditions; and (b) outputing at least one proportion as a slide handling monitor parameter (1112) wherein the at least one proportion is selected from the group consisting of barcode error failure proportion, positioning error failure proportion, cleaning error failure proportion, and overall slide handling quality failure proportion.

21. The laboratory process monitoring method of claim 1 wherein the step of extracting an initial monitor parameter (108) further comprises the step of extracting at least one preparation monitoring parameter (1114) for monitoring the quality of a laboratory fixation, staining, or coverslip application processes.

22. The laboratory process monitoring method of claim 21 wherein the at least one preparation monitoring parameter (1114) is selected from the group consisting of a bubble adequacy category (222), a mounting medium adequacy category (226), a staining adequacy category (224), and an additional adequacy category (238).

23. The laboratory process monitoring method of claim 22 wherein the staining adequacy (224) further comprises a light stain adequacy category (228), nuclear stain adequacy category (230), cytoplasm stain adequacy category (232), chromatin adequacy category, and N/C contrast adequacy category (236).

24. The laboratory process monitoring method of claim 22 wherein the additional adequacy category (238) further comprises staining score adequacy category (240), stage3 alarm category (242), QC
score category (244), and chromatin details category (246).

25. The laboratory process monitoring method of claim 9 wherein the step of applying reduced process suitability limits further comprises the step of generating reduced process suitability limits by adjusting limits of features used in suitability tests that determine a reliability of other slide scores (118), wherein adjustment is applied only to feature limits that are not exceeded by feature values of slide data, and wherein adjusted limits comprise an average of an original limit and a closest feature value of slide data.

26. The laboratory process monitoring method of claim 6 wherein the step of dynamically updating a set of slide batches (302, 304) further comprises the step of continuously forming and undating two batches (116) including a short-term batch and a mid-term batch.

27. The laboratory process monitoring method of claim 26 wherein the short-term batch (116) includes up to a first predetermined number of most recently processed laboratory slides.

28. The laboratory process monitoring method of claim 26 wherein the mid-term batch (116) comprises a superset of the short-term batch and comprises up to a second predetermined number of most recently processed slides and wherein a laboratory process is considered "out of range" if values of monitoring (114) parameters for the mid-term batch are outside control limits (132).

29. The laboratory process monitoring method of claim 26 wherein the step of continuously forming and updating two batches (302, 304), including a short-term batch and a mid-term batch, further includes the step of reporting recent variations in -laboratory process (118) based on the short-term batch that can be adjusted before adverse screening conditions occur, thereby allowing tracking of variation patterns, and providing the means to forecast adverse conditions.

30. The laboratory process monitoring method of claim 14 wherein the step of extracting at least one - specimen collection monitoring parameter (202) further comprises the steps of:
(a) testing at least one slide specimen collection monitoring category (202) by measuring the proportions of slides in a given batch that fail any scanning failure conditions or process suitability conditions (1132); and (b) outputting at least one proportion as a specimen collection characteristic parameter (202) wherein the at least one proportion is selected from the group consisting of scanty material proportion (208), distribution failure proportion, variable material distribution failure proportion (210), and overall material quality failure proportion.

31. The laboratory process monitoring method of claim 22 wherein the step of extracting at least one preparation monitoring parameter (1114) further comprises the steps of:

(a) testing at least one preparation monitoring category by measuring the proportions of slides in a given batch that fail any scanning failure conditions or process suitability conditions (1160); and (b) outputting at least one proportion as a preparation monitoring parameter (1114) wherein the at least one proportion is selected from the group consisting of bubble adequacy failure proportion (222), mounting medium failure proportion (226), light stain failure proportion (228), nuclear stain failure proportion (230), cytoplasm stain failure proportion (232), chromatin adequacy failure proportion (234), N/C contrast adequacy failure proportion (236), overall staining adequacy failure proportion (224), and combined bubble mounting, medium and staining adequacy failure proportion.

32. The laboratory process monitoring method of claim 22 wherein the step of extracting at least one preparation monitoring parameter (1114) further comprises the step of outputing at least one preparation monitoring parameter (1114) from the group consisting of a staining score parameter (240), a stage3 alarm parameter (242) , a QC score parameter (244), a population beyond global QC
score upper bound parameter (248) and a chromatin details parameter (246).

33. The laboratory process monitoring method of claim 9 wherein the step of applying a global analysis score upper bound (248) further comprises the step of determining a global analysis score upper bound using successfully processed normal slides that are ranked by their analysis scores.