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- Title
Cross-calibration of the Siemens mMR: easily acquired accurate PET phantom measurements, long-term stability and reproducibility.
- Authors
Keller, Sune; Jakoby, Björn; Svalling, Susanne; Kjaer, Andreas; Højgaard, Liselotte; Klausen, Thomas
- Abstract
Background: We present a quick and easy method to perform quantitatively accurate PET scans of typical water-filled PET plastic shell phantoms on the Siemens Biograph mMR PET/MR system. We perform regular cross-calibrations (Xcal) of our PET systems, including the PET/MR, using a Siemens mCT water phantom. Long-term stability: The mMR calibration stability was evaluated over a 3-year period where 54 cross-calibrations were acquired, showing that the mMR on average underestimated the concentration by 16 %, consistently due to the use of MR-based μ-maps. The mMR produced the narrowest calibration ratio range with the lowest standard deviation, implying it is the most stable of the six systems in the study over a 3-year period. mMR accuracy with predefined μ-maps: With the latest mMR software version, VB20P, it is possible to utilize predefined phantom μ-maps. We evaluated both the system-integrated, predefined μ-map of the long mMR water phantom and our own user-defined CT-based μ-map of the mCT water phantom, which is used for cross-calibration. For seven scans, which were reconstructed with correctly segmented μ-maps, the mMR produced cross-calibration ratios of 1.00-1.02, well within the acceptance range [0.95-1.05], showing high accuracy. Conclusions: The mMR is the most stable PET system in this study, and the mean underestimation is no longer an issue with the easily accessible μ-map, which resulted in correct cross-calibration ratios in all seven tests. We will share the user-defined μ-map of the mCT phantom and the protocol with interested mMR users.
- Subjects
POSITRON emission tomography; COMPUTED tomography; MAGNETIC resonance; STANDARD deviations; QUALITY control
- Publication
EJNMMI Physics, 2016, Vol 3, Issue 1, p1
- ISSN
2197-7364
- Publication type
Article
- DOI
10.1186/s40658-016-0146-3