Abstract:
An automated immunoassay analyzer, or assay system, provides for frequent testing of control samples to verify that before and after a series of tests of patients&#39; samples, the operation of the test equipment is accurate, thereby ensuring that the results of the series of patient tests are accurate. Operating the immunoassay analyzer in this manner will delay reporting clinical test results until the results are confirmed as accurate. This operation can be performed automatically by a random access immunoassay analyzer.

Description:
[0001]    This application claims the benefit of U.S. application Ser. No. 10/817,998, filed Apr. 5, 2004, which claims benefit of U.S. Provisional Application No. 60/463,101, filed Apr. 15, 2003. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to automatic testing of biological samples, for example, the use of an immunoassay analyzer for medical tests on human subjects and, more particularly, to coordinating the testing of control samples with the testing of patient samples to insure accuracy of the patient sample test results. 
         [0003]    Testing of biological material is widely employed in the practice of medicine, as well as in other disciplines wherein information about biological material is required. Of particular interest is automated testing for the presence of disease in samples of biological material from human patients. Such testing is frequently accomplished by the use of automated equipment, such as an immunoassay analyzer, wherein samples of bodily fluids obtained from patients are aspirated into the testing machinery which then performs tests and provides the results of those tests. 
         [0004]    The testing and reporting of the results must be performed accurately to insure that patients receive proper treatment, and to avoid faulty diagnosis of the patient&#39;s condition. In order to insure accuracy in the testing procedure, equipment employed in the testing process must be calibrated to ensure that vital parameters, such as the amount of fluid aspirated in a test sample, the temperature of an aspirated sample, and other parameters determined by the testing equipment are measured correctly. 
         [0005]    In order to ensure the necessary accuracy in the testing procedure, control samples of known material, often referred to as controls, are tested in the test equipment, such as the immunoassay analyzer. The control samples typically contain biological material of known composition, to ensure that the testing equipment is operating properly and providing the correct results. For example, control tests can include the determination of the amount of acidity in the control material, or the presence of spectral lines in a spectroscopy examination of the control material. 
         [0006]    Generally, the calibration and control runs are made before starting the patient&#39;s tests, such as at the beginning of the day. Then, the results of patient tests conducted during the day can be presumed to be valid. However, test equipment can gradually lose accuracy during a day of testing. This presents a problem because the results of tests conducted later in the day may be invalid or inaccurate. Thus, there is a need for a procedure to provide improved monitoring of the operation of the testing equipment on a relatively continuous basis to ensure that the testing equipment is operating accurately even after a relatively short series or run of patient tests. 
       SUMMARY OF THE INVENTION 
       [0007]    In accordance with the present invention an automated immunoassay analyzer, or assay system, provides for frequent testing of control samples to verify that before and after a series of tests of patients&#39; samples, the operation of the test equipment is accurate, thereby ensuring that the results of the series of patient tests are accurate. Operating the immunoassay analyzer in this manner will delay reporting clinical test results until the results are confirmed as accurate. This operation can be performed automatically by a random access immunoassay analyzer. 
         [0008]    In practicing the invention, the control testing should be performed more frequently than the calibration testing because the immunoassay analyzer tends to retain its calibration ability for longer periods of time than its capability to maintain the accuracy of its performance of the control tests. 
         [0009]    Accordingly, the calibration test is performed before and after a relatively long series of patient tests, whereas the control testing is performed before and after a relatively short series of patient tests. For example, it can be desirable to run a series or set of control tests once every hour, wherein the interval of time between sets of control tests may be based on experience in operating the immunoassay analyzer. 
         [0010]    The result of a control test can be referred to as an index representing a numerical value. The control test index can be described with reference to a window or range of acceptable indices such that, depending on the specific test, a control test index is required to fall within the window. The result of a patient test can also be referred to as an index. 
         [0011]    In a preferred embodiment of the invention, three different control tests are performed where the indices are to fall within the window, and a single control test can be provided for an index falling below the lower boundary of the window, and a further single control test can be provided for an index falling above the upper boundary of the window. 
         [0012]    The procedure of the invention can be demonstrated with respect to the control testing, wherein a sequence of successive runs of patient tests is bracketed or interleaved with a sequence of sets of control tests. Thus, a set of control tests precedes and follows a run of patient tests. For example, a first set of control tests and a second set of control tests bracket a first run of patient tests. 
         [0013]    After the second set of control tests, the patient tests are resumed until a third set of control tests is run. Thus, the second and the third set of control tests bracket the second run of patient tests. The two sets of control tests that bracket a specific run of patient tests must show proper operation of the immunoassay analyzer in order to validate the results of the run of patient tests, and enable the reporting of the results of the patient tests. 
         [0014]    In the event that the analyzer has not performed the set of control tests that follow a run of patient tests over an extended period of time, for example, 10 hours, then the results of the patient tests of that nm are discarded because the late testing of controls may not represent the current status of the analyzer for patient tests conducted several hours earlier. 
         [0015]    It is recognized that an interval of incubation time that can vary from about 15 to about 45 minutes is required after the aspiration of a set of control tests in order to establish the results of the control tests. To save time, it can be desirable to resume the patient testing, rather than wait until the results of the control tests have been established. Thus, patient sample aspirations do not have to await control test results before starting, only that the control has already been aspirated. 
         [0016]    If the control tests show a defective analyzer, then the results of the patient testing in the run of patient tests which preceded the defective control results, as well as the results of the patient testing in the run of patient tests which followed the defective control results are discarded. 
         [0017]    By interleaving or bracketing the sequence of runs of patient tests with the sequence of control tests, the immunoassay analyzer, or other material testing device can automatically perform the task of ensuring the accuracy of the patient test results before reporting the results. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    In the drawings: 
           [0019]      FIG. 1  is a simplified flowchart showing the procedure of the invention for interleaving a sequence of tests during the performance of an immunoassay analyzer with a sequence of runs of patient tests for confirming the accuracy of the results of the patient tests prior to reporting the results; 
           [0020]      FIG. 2  is a timing diagram showing bracketing runs of patient tests with sets of control tests to implement the procedure of  FIG. 1 ; 
           [0021]      FIG. 3  is a schematic diagram of an immunoassay analyzer operating in accordance with the procedure of the invention; and 
           [0022]      FIG. 4  is a simplified flowchart similar to  FIG. 1 , showing additional options and features of the invention. 
       
    
    
       [0023]    Identically labeled elements appearing in different figures refer to the same element but may not be referred to in the description for all figures. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    With reference to  FIG. 1 , the procedure of the invention is applicable to the operation of an assay system, such as a sample-testing apparatus, and more particularly to the automated immunoassay analyzer employed in a preferred embodiment of the invention. The procedure begins at block  10  with a calibration of the assay system. Typically, the calibration test will determine whether the volume of a quantity of liquid or the acidity of the liquid (pH value), for example, is being correctly measured by the assay system equipment. In the case of the automated immunoassay analyzer, the calibration test can involve aspirating a known quantity of liquid from a sample followed by comparing the measured value of the quantity of liquid with the known quantity. 
         [0025]    The results of the calibration step can be awaited before proceeding with block  12  or, if desired, one can proceed immediately to block  12  and run a control set of system tests. If the results of the calibration tests are awaited before running the control set, the control set would be run after a successful completion of the calibration tests. Calibration tests are used to establish measurement parameters, whereas control tests are used to make sure that the analyzer is operating properly with the established parameters. 
         [0026]    If the calibration tests indicate a problem with the assay system, appropriate adjustments would be made to obtain proper calibration prior to running the control set. However, if the assay system had been recently tested, and it is presumed that the assay system is operating properly, some patient tests can be conducted with the results withheld until the results of the calibration and of the control set have been ascertained. Thereafter, the results can be provided to the patient or to the health-care provider, such as by use of a display or printer of the assay system. If there is a failure of a calibration test or a failure of a test of the control set, the patient tests would need to be rerun, and the results of the prior patient tests would be discarded. 
         [0027]    For example, at block  12 , the control set of tests can consist of four samples of known material to be applied to four separate tests with four separate reagents and possibly a spectrographic test. In the use of the control set, the correct results are known beforehand. Thus, if the assay system produces the correct results from the tests, the outputting of the correct results is an indication of proper and accurate operation of the assay system. 
         [0028]    Each test of the control set is formulated to provide a numerical result that must fall within a range of values. For example, a numerical result must fall within a window of acceptable results, the window extending from a lower limit to an upper limit of acceptable values. Alternatively, an acceptable value must fall in a range below an upper limit or in a range above a lower limit. 
         [0029]    Thus, in the case of an automated assay system, the system has a computer to compare the results of a control test with the acceptable range of values and outputs an indication of a successful test or a failed test. Similarly, in the case of a calibration test run in block  10 , the computer tests a measured value, such as the volume of a liquid or the acidity of the liquid against the known validity criteria to output the indication of a successful test or a failed test. 
         [0030]    If both the calibration tests and the control tests are nm prior to the inception of the patient testing, the procedure of  FIG. 1  advances to block  14  wherein it is determined whether the measured levels in the tests of the control set are within the specified ranges. In the event that the control levels are not within the specified ranges, block  16  is activated and the control set must be rerun at block  12 . In the event that the control levels are within the specified ranges, block  18  is activated and the procedure advances to block  20  wherein a control bracket is opened. 
         [0031]    The terminology “control bracket” is employed to indicate a set of patient sample tests preceded by a control set and followed by a control set. The “opening” of the control bracket initiates the set of patient sample tests. The “closing” of the control bracket terminates of the set of patient sample tests. 
         [0032]    At block  22 , the set of tests on the patient samples is nm. In accordance with one aspect of the invention, the reporting of the test results of the patient samples by means of a display, printout, or other means of communication is withheld until the control bracket is successfully closed. 
         [0033]    The “successful closing” of the control bracket means that the concluding set of control tests, which follows the set of the patient tests, indicates that the assay system is operating correctly. 
         [0034]    Accordingly, at block  24 , the control set that follows the set of the patient tests is activated. At block  26  it is determined whether all the control levels of the control set at block  24  are in the specified ranges. If the control levels are within the specified ranges at block  28 , then the control bracket is successfully closed at block  30 , and the patient results are released, such as by presentation on a display or printout of the assay system. 
         [0035]    In the event that the control levels are not within the specified ranges at block  32 , then, at block  34 , there is a purging of the patient results from the assay system, and the procedure reverts to block  12  for a running of the control set. 
         [0036]    It should also be noted that at the time of the initial calibration of the assay system at block  10 , if there are previous patient results that have been withheld, then these patient results should be purged from the assay system at block  34  prior to commencing the miming of the control set at block  12 . This ensures that there is no inadvertent release of patient data where it has not been ascertained that the data is accurate. 
         [0037]      FIG. 2  provides a further description of the invention by means of a timing diagram showing the succession of steps in the procedure. As shown at the top of the diagram, at block  36 , the procedure begins with running a set of calibration tests, with individual tests indicated by slots  38 . 
         [0038]    Upon completion of the calibration tests, the procedure advances to block  40  for performance of the sequence of tests of the control set. Individual tests of the control set are indicated by slots  42 . 
         [0039]    Upon completion of the control set, the procedure advances to block  44  for performance of the sequence of tests on patient samples. In block  44 , slots  42  indicate individual tests. Several slots  42  are indicated by way of illustration to represent that in actual practice of the invention, hundreds of patient samples can be tested in block  44 . 
         [0040]    Upon completion of the sequence of patient tests of block  44 , the procedure continues at block  46 , wherein individual tests of the control set are indicated by slots  42 . This is followed by a further sequence of testing of patient samples at block  48  which, in turn, is followed by the running of tests of a further control set at block  50 . 
         [0041]    The sequence of tests of the control set of block  40 , which precedes the sequence of the testing of the patient samples at block  44 , and the sequence of tests of the control set of block  46 , which follows the testing of the patient samples of block  44 , are said to bracket the testing of the patient samples of block  44 , such bracketing being indicated at  52 . 
         [0042]    Correspondingly, the control set at block  46  and the subsequent control set at block  50  bracket the testing of the patient samples of block  48 , this bracketing being indicated at  54 . 
         [0043]    The timing diagram of  FIG. 2  shows a further testing of patient samples at block  56  followed by calibration tests at block  58  followed by a further control set at block  60 . The control sets at the blocks  50  and  60  bracket the patient samples at block  56  as indicated at  62 . Upon the successful conclusion of the bracket  52 , there is an announcement of the results of the testing of the patient samples at block  44  of the bracket  52 . Similarly, there is an announcement of the results of the patient samples of block  48  upon the successful conclusion of its bracket  54 , and an announcement of the results of the testing of the patient samples of the block  56  upon a successful conclusion of its bracket  62 . 
         [0044]    In the event that calibration tests, such as the calibration tests at block  58  of the bracket  62 , indicate a need for recalibration, the results of the tests of the patient samples of block  56  are discarded, as indicated at arrow  59 , and are not announced. Only samples between control sets using the same accurate calibration parameters are released. The handling of the recalibration situation will be described further with reference to  FIG. 4 . 
         [0045]      FIG. 2  indicates a repetition of the calibration sets of tests at less frequent intervals than the rate of repetition of the control sets of tests. Thus, there is an interleaving of sequences of tests of the calibration sets and of the control sets and of the patient sample sets. 
         [0046]      FIG. 3  is a schematic diagram of a system  64  for conducting the procedure of the invention. System  64  generally represents immunoassay equipment including the immunoassay analyzer of the invention. It is understood that the specific components of such equipment may vary depending on the needs of the user of the equipment. 
         [0047]    The system  64  comprises testing apparatus  66  and conveyor apparatus  68  for conveying samples  70  to be tested at workstations  72  of the testing apparatus  66 . While the system  64  operates automatically, it is understood that the procedure of the invention can also apply to manually operated equipment. 
         [0048]    By way of example in the system  64 , four workstations  72  are shown. It is understood that a greater or lesser number of workstations can be employed. The four workstations are identified as  72 A,  72 B,  72 C and  72 D. Each of the workstations  72 A,  72 B and  72 D includes a vial  74  and an aspirator  76  for extracting into the vial  74  a predetermined portion of a sample to be tested, as well as a sensor  78  for sensing the contents of the vial  74 . The workstation  72 C, for example, includes an aspirator  76  with a spectrometer  80  for determining the spectral characteristics of an aspirated sample. The testing apparatus  66  also comprises a computer  82 , a memory  106 , a display  84  for outputting results of a test, and a store  86  for storing reagents to the placed in the vials  74  for conducting the tests. 
         [0049]    The conveyor apparatus  68  comprises two input conveyor belts  88  and  90  coupled by a selector  92  to a third conveyor belt  94 . The selector  92  can be a mechanical switch which offsets the position of either one of the input belts  88  and  90  to be in alignment with the third belt  94 , to thereby enable articles carried by one of the selected input belts  88  and  90  to be passed on to the third belt  94 . The conveyor belts  88 ,  90  and  94  are supported by a plurality of drive rolls, two of which are shown at  96  and  98 , for imparting motion to the belts in the direction of arrow  100 . 
         [0050]    A drive unit  102 , operated by signals from the computer  82 , is shown connected to the roll  98  for imparting rotation to the roll  98  to carry sample holders  104  along the third conveyor belt  94 . It is understood that further connections, not shown, are provided between the drive unit  102  and other drive rolls of the conveyor apparatus  68  for selectively driving the input belts  88  and  90 . 
         [0051]    The sample holders  104 , located on the first input conveyor belt  88 , carry patient samples to be tested by the conveyor apparatus  68  while further sample holders  104 , located on the second input conveyor belt  90 , carry control samples to be tested by the system  64 . Some of the control samples on the second input conveyor belt  90  can be employed for conducting the calibration tests of the system  64 . 
         [0052]    The selector  92  operated by the computer  82  provides for an alternative coupling of sample holders  104  of either the first conveyor belt  88  or the second conveyor belt  90  to the third conveyor belt  94 . 
         [0053]    In the operation of the system  64 , the computer  82  directs the selector  92  to select the samples  70  of the second belt  90  to be coupled onto the third belt  94  for conducting the calibration tests as described above with reference to block  36  of  FIG. 2 , and also for conducting the tests of a control set as described above with reference to block  40  of  FIG. 2 . 
         [0054]    For conducting tests on patient samples, the computer  82  directs the selector  92  to select the samples  70  of the first belt  88  to be coupled onto the third belt  94  for conducting the patient sample tests as described above with reference to block  44  of  FIG. 2 . 
         [0055]    With respect to conducting any one of the tests, whether a calibration test or a test of the control set, or a patient sample test, the holders  104  contain a known quantity of the samples  70 . A sensor  78  in any one of the workstations  72  can be tested during a calibration test by measuring the liquid, or other material, within the respective vial  74 . The sensor  78  can also be employed in a control test or a patient sample test to measure the amount of product or other characteristic of a chemical reaction within the respective vial  74 . By operation of the selector  92 , in combination with activation of the conveyor drive unit  102 , the computer is able to sequence the procedures conducted by the system  64  in accordance with the format presented in the timing diagram of  FIG. 2 . 
         [0056]    The computer  82  directs the conveyor drive unit  102  to bring the sample holders  104  to respective locations under the aspirators  76 , whereupon the aspirators  76  aspirate predetermined quantities of the samples  70  into the vials  74 . Alternatively, a single sample  70  can be processed by successive workstations  72 A,  72 B,  72 C and  72 D wherein each workstation performs a separate test on the specific sample. The operation of an aspirator  76  is controlled by the computer  82 . The computer also directs the store  86  to inject predetermined amounts of reagents into respective ones of the vials  74 . 
         [0057]    The chemical reaction between the reagent and the sample in any one of the vials  74  can produce, for example, a change in color, a change in temperature, or a quantity of precipitate which can be sensed by the sensor  78 . 
         [0058]    In the case of the workstation  72 C, material of a sample aspirated by the aspirator  76  is supplied to the spectrometer  80 , and spectrographic data outputted by the spectrometer  80  is transmitted to the computer  82 . Values sensed by the sensor  78  are transmitted to the computer  82  for evaluating the results of the tests. 
         [0059]    In accordance with another aspect of the invention, the results of the tests on the patient samples are held within the memory  106  of the computer  82  until the closing of a bracket, as described in  FIG. 2 , prior to being transmitted to the display  84 . 
         [0060]    The results are presented on the display  84 , or otherwise communicated such as by being printed by a printer of the display  84  or being transmitted electronically to a remote station, only after a successful closure of the bracket. 
         [0061]    As already described, successful closure of the bracket only occurs when the tests of the control sets conducted both before and after a sequence of patient samples tests are found to produce acceptable results. 
         [0062]    This is demonstrated in  FIG. 2  wherein, after a successful conclusion of the control set of block  46 , there may be an announcement of the test results of the patient samples of block  44 . Also, after successful conclusion of the control set of block  50  there can be an announcement of the test results of the patient samples of block  48 . A program for operation of the computer  82  may also be stored in the memory  106 , providing for operation of the system  64  under direction of the computer  82  in accordance with the invention. 
         [0063]      FIG. 4  shows procedural operations which are in addition to and alternative to the procedural operations disclosed in  FIG. 1 . The procedure begins at block  120  with a running of the calibration tests of the immunoassay analyzer. This is followed at block  122  with the running of the control set for the immunoassay analyzer. Thereupon, at block  124 , there is a running of the sequence of the patient sample tests, wherein the results of the patient tests are quarantined by holding the results in the computer memory  106  of  FIG. 3 . In the example of the operation of the assay equipment presented by the sequence of blocks  120 ,  122  and  124 , the patient tests have been run immediately after the running of the calibration tests and the control tests. 
         [0064]    In this example, the patient tests have been nm before obtaining the results of the calibration tests and the control tests. Therefore, the results of the patient tests are not to be released and are to be withheld, or quarantined, until a later time when the results of the calibration tests, the control tests preceding the patient tests, and a further set of control tests which follow the patient tests have been obtained and are found to be accurate. 
         [0065]    Thus, at block  126  it is determined whether any calibration tests are still being run. In the event that calibration tests are still being run, at block  128  the procedure waits until the results of the calibration tests are obtained and evaluated. 
         [0066]    In the event that the calibration is found to be valid at block  130 , the procedure advances to block  132  where it is determined whether the set of control tests are running. If the control test set is not being run, then at block  134  the control set is run, which is the control set that follows the patient tests of block  124 . The procedure then waits for the results of the control tests to be evaluated at block  136 . If the results of the control set are in their proper ranges at block  138 , the procedure advances to block  140  to observe whether there are any patient test results in quarantine, namely, being stored in the computer memory  106  of  FIG. 3 . 
         [0067]    In the situation under consideration, patient tests were nm at block  124 , and the results were quarantined. Accordingly, the procedure advances from block  140  to block  142  wherein the patient test results are released from quarantine. 
         [0068]    The releasing from quarantine is accomplished in  FIG. 3  by a reading of the results from memory  106  for presentation on the display  84 . 
         [0069]    After announcing the patient test results at block  142 , the procedure can then revert via blocks  144 ,  146  and  148 , to run more patient tests at block  124 . At block  144  it is determined whether it is necessary to recalibrate the assay equipment. In the situation under consideration, the equipment has been recently recalibrated at block  120 . Therefore, it is not necessary to recalibrate at this time, and the procedure advances to block  146  wherein it is determined whether any of the control test results which bracket the patient test results are too old. This is determined by a time comparison. Typical specific time parameters that serve as criteria to recalibrate are about 14 days and to rerun a control test are about 24 hours. 
         [0070]    In the situation under consideration, all the control tests were run recently, and the procedure advances to block  148  to determine whether there are additional patient tests to be nm. If more patient tests are to be run, then the procedure advances to block  124  for running more patient tests. 
         [0071]    It is noted that at any point in the process, when the results of a control set reach a predetermined age, such as 24 hours, all patient tests in progress, as well as patient results which were quarantined after the control results were evaluated, are discarded instantly if still quarantined. This ensures that only recent control test results are employed for ensuring the testing accuracy of the patient samples. A time of 24 hours is generally set for default. However, the user can set the time interval as desired. 
         [0072]    Variations in the foregoing procedure are now considered. Previously, at block  126 , it was said that the assay calibration tests were still running. However, in the event that the calibration tests are not currently running, the procedure advances from block  126  to block  130  to determine whether the previously completed calibration runs produced valid results. 
         [0073]    At block  130 , it was previously assumed that the calibration was valid. However, in the event that the calibration tests results are not in their appropriate ranges, the procedure reverts via block  150  to block  120 . At block  150  the patient test results which were quarantined are discarded, this being accomplished in  FIG. 3  by a dumping or erasing of the patient test results from the memory  106 . The calibration tests are then rerun at block  120 . 
         [0074]    In reference to a further possible situation, one may begin the procedure at block  120  shortly after having run some patient tests, which were properly bracketed by control tests, after which further patient samples were presented for testing. In this situation, it is not necessary to rerun the calibration tests, but simply to check the results of the calibration tests at block  128 . This step of the procedure is indicated by a line connecting block  120  with block  128 . 
         [0075]    In the previous discussion of block  132 , it was assumed that the tests of the control set were not running and, accordingly, the tests were run at block  134 . In this connection, it is noted that additional sets of the control tests can be run from time to time to insure accuracy of the results of the patient tests. If, at block  132 , it were noted that tests of the control set are presently running, then the procedure would advance from block  132  directly to block  136  to await evaluation of the results of the control set. 
         [0076]    In the previous discussion of block  138 , it was assumed that the results of the control tests were in the proper range, in which case the procedure advanced from block  138  to block  140 . However, in the situation wherein there are results of the control tests that are not in the proper ranges, the procedure advances to block  152  wherein the results of the patient tests, which are held in quarantine, are discarded, and the procedure reverts to block  130  to determine if the results of the calibration tests are valid. 
         [0077]    In the previous discussion of block  140 , it was assumed that there were patient results to be released from quarantine. However, in the situation wherein there are no patient results in quarantine, the procedure advances to block  154  to inquire whether there are any patient tests currently in progress. If patient tests are currently in progress, then the procedure reverts from block  154  to block  130  to determine if the results of the calibration tests are valid. If, at block  154 , it is determined that no patient tests are presently in progress, then the procedure advances to block  146  wherein, as described above, it is determined whether the most recent valid control results are too old. The specific time parameters for “too old” are determined by the user. As noted above in a previous example of aging test results, when the results of a control set reach a determined age, such as 24 hours, all patient tests in progress, as well as patient results which were quarantined after the control results were evaluated, were also discarded if still quarantined. 
         [0078]    At block  144 , in the previous description, it was assumed that there was no need to recalibrate the assay equipment, in which case the procedure advanced to block  146 . However, at block  144 , if it is determined to be necessary to recalibrate the assay equipment, then the procedure advances via block  156  back to block  120 . At block  156 , there is a discarding of results of any patient tests which may be in progress or which may be in quarantine, after which the calibration tests of the assay equipment are rerun at block  120 . 
         [0079]    At block  146 , in the previous description, it was assumed that the most recent valid results of control tests were timely. Therefore, the procedure could advance to block  148  to determine if there were more patient tests to be nm. However, in the event that results of the most recent control tests are too old, then the procedure reverts from block  146  to block  122  for a rerunning of the tests in the control set. At block  148 , if there are no more patient tests to be run, then the procedure recycles back through block  146  in a waiting loop until more patient samples arrive for testing. 
         [0080]    It is to be understood that the above described embodiments of the invention are illustrative only, and that modifications thereof may occur to those skilled in the art. Accordingly, this invention is not to be regarded as limited to the embodiments disclosed herein, but is to be limited only as defined by the appended claims.