Process control and data handling in clinical chemistry by a laboratory computer
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The thesis describes the development and assessment of a clinical chemistry computer system based on the Elliott 903C computer obtained for the on-line monitoring of automated equipment and the subsequent processing of the data derived. The special hardware required for interfacing the automated equipment with the computer was designed and constructed by Elliott Medical Automation Limited. All the software required for the operation of the system was written by the manufacturer's programming staff and my part was to be closely involved with general systems analysis. A detailed account is given of the evaluation of all the parameters required for the on-line monitoring of AutoAnalyzers and the provision of information required for calculation routines, checking quality control results, defining ranges for the automatic flagging of abnormal results, etc. The development work, including the testing, proving and where necessary, the modification of programs, was carried out in the Royal Infirmary, Edinburgh, with the assistance of the technical staff of the laboratory. In the initial stages of development the computer system was run in parallel with the existing laboratory equipment to enable a full assessment of the system to be carried out. This included assessing the performance of process control functions and the chemical acceptability of the system. At a later stage an assessment was made of the routine operation of the computer system when interest was focused on the time taken to perform individual tasks and the reliability of the hardware components. With the exception of one aspect of peak detection, the data acquisition programs were found to operate in a satisfactory manner, and the accuracy and precision of the computer system was at least as good as that of the routine laboratory methods; these latter involved manual reading and interpretation of recorder charts. The individual data processing programs were validated but when the programs were integrated to form a total software system, considerable delays in processing were encountered. Despite several attempts to reduce the time taken to perform processing routines, it was found impracticable to carry out the data handling activities of the laboratory within an acceptable time scale using the existing hardware configuration. The computer system is currently in use on a seven-day week basis for monitoring analytical equipment and performing the following functions (1) Acquisition of raw data from as many as 19 different determinations on up to 12 AutoAnalyzer channels at one time. (2) Peak detection and validation. (3) Calculation of results after correction for instrumental drift. (4) Output of results identified by cup number. (5) Calculation of mean and standard deviation of patient specimens. The present mode of operation removes the need for manual reading of AutoAnalyzer charts and hence reading errors, but it involves the transcription of results from the computer print-out to manually prepared work sheets, and the further transcription of results from work sheets to patient reports. The benefits derived from the Elliott 903 computer in its present form of operation can be summarised as follows: (1) It has been possible to increase the laboratory throughput without a substantial increase in staff in spite of an increase in the numbers of technical staff attending classes of further education during working hours. This has resulted in an increase in productivity and a decrease in the average cost per determination. (2) There is a decrease in the number of human errors by the elimination of reading of recorder charts. (3) Quality control statistics are available while they are still relevant to the current situation. The extension or modification of the hardware configuration and the additional software required to meet the needs of this laboratory have been investigated. Consideration has been given to the possibility of completely replacing the present computer system and to the feasibility of linking the laboratory system to a remotely situated data processing computer system.