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Computational and Mathematical Methods in Medicine
Volume 2017 (2017), Article ID 9830386, 9 pages
https://doi.org/10.1155/2017/9830386
Research Article

Uncertainty Analysis in the Calibration of an Emission Tomography System for Quantitative Imaging

1ENEA, National Institute of Ionizing Radiation Metrology, Via Anguillarese 301, 00123 Rome, Italy
2National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK

Correspondence should be addressed to Marco D’Arienzo; ti.aene@ozneirad.ocram

Received 12 June 2017; Accepted 15 August 2017; Published 12 October 2017

Academic Editor: David A. Winkler

Copyright © 2017 Marco D’Arienzo and Maurice Cox. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

It is generally acknowledged that calibration of the imaging system (be it a SPECT or a PET scanner) is one of the critical components associated with in vivo activity quantification in nuclear medicine. The system calibration is generally performed through the acquisition of a source with a known amount of radioactivity. The decay-corrected calibration factor is the “output” quantity in a measurement model for the process. This quantity is a function of a number of “input” variables, including total counts in the volume of interest (VOI), radionuclide activity concentration, source volume, acquisition duration, radionuclide half-life, and calibration time of the radionuclide. Uncertainties in the input variables propagate through the calculation to the “combined” uncertainty in the output quantity. In the present study, using the general formula given in the GUM (Guide to the Expression of Uncertainty in Measurement) for aggregating uncertainty components, we derive a practical relation to assess the combined standard uncertainty for the calibration factor of an emission tomography system. At a time of increasing need for accuracy in quantification studies, the proposed approach has the potential to be easily implemented in clinical practice.