Speakers
Description
Background: IMAS is a long axial field-of-view (LAFOV) positron emission tomography (PET) system with time-of-flight (TOF) and depth-of-interaction (DOI) capabilities. This study aims to develop and demonstrate a practical quality control (QC) method to monitor the stability and reproducibility of DOI correction in the IMAS.
Methods: System stability was assessed using both $^{22}\mathrm{Na}$ point sources and capillary sources. $^{22}\mathrm{Na}$ sources mounted in a clinical PET/CT alignment holder were measured in three acquisitions over multiple days to evaluate reproducibility. Stability was quantified by comparing relative distances between reconstructed sources after DOI correction. Capillary sources prepared according to the NEMA NU 2 protocol were used to assess spatial resolution via FWHM in radial direction.
Results: Relative point-source positions remained largely consistent across the three acquisitions. The largest deviation of 1.94 mm occurred after holder repositioning, while differences between acquisitions without repositioning remained below 1 mm. Absolute position comparisons showed small deviations from the experimentally determined ground-truth positions, generally within 2–3 mm. All DOI-corrected reconstructed positions remained within the assumed 5 mm ground-truth uncertainty. Spatial resolution measurements confirmed previously reported FWHM behavior, with DOI correction improving radial resolution and reducing degradation at larger radial offsets.
Conclusion: The proposed QC approach enables practical monitoring of DOI correction stability in the IMAS LAFOV PET system. The results demonstrate stable DOI-corrected source positioning across repeated measurements and confirm expected spatial resolution performance. This method provides a simple and robust procedure for routine system quality control and long-term performance monitoring. Future studies will employ a dedicated holder specifically designed for this QC procedure.
Reconstructed point-source positions across three acquisitions at different radial distances from the center. Red markers (three per source) show reconstructions without DOI correction, while yellow markers show reconstructions with DOI correction. Blue markers indicate the experimentally determined ground-truth positions with an assumed uncertainty of 5 mm (dashed circle). All DOI-corrected reconstructions fall within the assumed ground-truth uncertainty.
| Track | TBPET |
|---|---|
| Presentation type | Oral |