Quantifying and reducing the effect of calibration error on variability of PET/CT standardized uptake value measurements

Catherine M Lockhart, Lawrence R MacDonald, Adam M Alessio, Wendy A McDougald, Robert K Doot, Paul E Kinahan

Research output: Contribution to journalArticlepeer-review


UNLABELLED: The purpose of this study was to measure the errors introduced by regular calibration of PET/CT scanners and to minimize the effect of calibration error on standardized uptake value measurements.

METHODS: Global calibration factors from 2 PET/CT scanners were recorded for 3.5 and 1.8 y, comparing manufacturer-recommended protocols with modified protocols to evaluate error contributions due to operator-influenced procedures. Dose calibrator measurements were evaluated using National Institute of Standards and Technology-traceable sources.

RESULTS: Dose calibrator variability was less than 1%, although there was a consistent bias. Global scaling variability was reduced from 6% to 4% for scanner 1 and from 11% to 4% for scanner 2 when quality assurance and quality control procedures were applied to the calibration protocol. When calibrations were done using a (68)Ge/(68)Ga phantom, the variability for both scanners was reduced to approximately 3%.

CONCLUSION: Applying quality assurance and quality control procedures to scanner calibration reduces variability, but there is a still a residual longitudinal scanner variability of 3%-4%. The procedures proposed here reduce the impact of operator error on scanner calibration and thereby minimize longitudinal variability in standardized uptake value measurements.

Original languageEnglish
Pages (from-to)218-24
Number of pages7
JournalJournal of Nuclear Medicine
Issue number2
Publication statusPublished - Feb 2011


  • Algorithms
  • Calibration
  • Cesium Radioisotopes/standards
  • Fluorine Radioisotopes/standards
  • Gallium Radioisotopes/standards
  • Germanium/standards
  • Image Processing, Computer-Assisted
  • Phantoms, Imaging
  • Positron-Emission Tomography/standards
  • Radioisotopes/standards
  • Radiopharmaceuticals/pharmacokinetics
  • Reference Standards
  • Reproducibility of Results
  • Tomography, Emission-Computed/standards


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