Laboratory and Instrument Quality Control

  • Derek Pearson
  • Nigel Lawson


Clinical trials now run for many years. Sponsors need assurance that the instruments they use remain stable over that length of time and report consistent results. It is important, however, to clarify the difference between quality assurance (QA) and quality control (QC). During any process, there should be ongoing process control. This is usually an automatic feedback situation. Quality control is the ongoing sampling of the process being evaluated. This allows for change in the process, but not normally immediately, unless sampling and analysis is rapid. Quality assurance is the evaluation of the quality control process or audit. It is normally conducted periodically and is a sampling process of the quality control process to ensure the described checks are being conducted. For example, in a manufacturing line where, say, washers are being made, the mean weight of the washers being produced may be evaluated. If the average weight of the washers varies beyond predetermined limits, the mix may be adjusted to keep the washers within basic limits. For every one hundred washers made, one will be taken and carefully measured. If the washer is outside predefined limits, then the manufacturing process may be adjusted and if necessary stopped and restarted, to ensure the washers are made to specification (quality control). Periodically an audit will be made of the whole process to ensure everything was conducted to all the written specifications (quality assurance). Quality control is the remit of the local investigator and quality assurance may form part of the audit carried out by the CRO, QA center or trial sponsor.


Control Chart Quality Control Data CUSUM Chart Quality Control Process Phantom Data 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. 1.
    Cawte SA, Pearson D, Green DJ, Maslanka WB, Miller CG, Rogers AT. Cross-calibration, precision and patient dose measurements in preparation for clinical trials using dual energy X-ray absorptiometry of the lumbar spine. Br J Radiol 1999; 72: 354–62.PubMedGoogle Scholar
  2. 2.
    Pocock NA, Babichev A, Culton N et al. Temperature dependency of quantitative ultrasound. Osteoporos Int 2000; 11: 316–20.PubMedCrossRefGoogle Scholar
  3. 3.
    Iid M, Kajita E, Mitamura S, Nishino H, Yamagami T, Nagahama N. Precision of quantitative ultrasound measurement of the heel bone and effects of ambient temperature on the parameters. Osteoporos Int 1999; 10: 462–7.CrossRefGoogle Scholar
  4. 4.
    Gluer C-C, Faulkener KG, Estilo MJ, Engelke K, Rosin J, Genart HK. Quality assurance for bone densitometry research studies: Concept and impact. Osteoporosis Int 1993; 3: 227–35.CrossRefGoogle Scholar
  5. 5.
    Lu Y, Matthew AK, Blunt BA et al. Dual X-ray absorptiometry quality control: Comparison of visual examination and process-control charts. J Bone Miner Res 1996; 11: 626–37.PubMedCrossRefGoogle Scholar
  6. 6.
    Westgard JO, Barry PL, Hunt MR, Groth T. A multi-rule Shewhart chart for quality control in clinical chemistry. Clin Chem 1981; 27: 493–501.PubMedGoogle Scholar
  7. 7.
    Orwoll ES, Oviatt SK, Biddle JA. Precision of dual-energy X-ray Absorptiometry: Development of quality control rules and their application in longitudinal studies. J Bone Miner Res 1993; 8: 693–9.PubMedCrossRefGoogle Scholar
  8. 8.
    Garland SW, Lees B, Stevenson JC. DXA Longitudinal quality control: A comparison of inbuilt quality assurance, visual inspection: multi-rule Shewhart charts and Cusum analysis. Osteoporos Int 1997; 7: 231–7.PubMedCrossRefGoogle Scholar
  9. 9.
    Pearson D, Cawte SA. Long-term quality control of DXA: A comparison of Shewhart rules and Cusum charts. Osteoporosis Int 1997; 7: 338–43.CrossRefGoogle Scholar
  10. 10.
    Faulkner KG, McClung MR. Quality control of DXA instruments in multicentre trials. Osteoporos Int 1995; 5: 218–27.PubMedCrossRefGoogle Scholar
  11. 11.
    BS5703 Guide to data analysis and quality control using Cusum techniques. London: British Standards Institution, 1980, 1981.Google Scholar
  12. 12.
    Pearson D, Kapasi T. A comparison of two methods of measuring gamma camera uniformity. Nucl Med Commun 1988; 9: 69–73.PubMedCrossRefGoogle Scholar
  13. 13.
    Knight AC, Williams ED. An evaluation of Cusum analysis and control charts applied to quantitative gamma-camera uniformity parameters for automated quality control. Eur J Nucl Med 1992; 19: 125–30.PubMedCrossRefGoogle Scholar

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© Springer-Verlag London 2002

Authors and Affiliations

  • Derek Pearson
  • Nigel Lawson

There are no affiliations available

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