Speaker
Description
Background
Depth-of-interaction (DOI) is one of the remaining challenges for high resolution PET. The resolution degradation stems from incorrect LOR endpoint estimation when photons impinge on the detector at oblique angles. This problem increases with distance from the symmetry axis, and poses a challenge for LAFOV PET, where more LOR are acquired at oblique angles. Terapet SA manufactures radiation detectors capable of localising gamma ray interactions in 3D within the detector volume. The aim of this project was to characterise the performance of a prototype PET scanner, called the Nuclyscan prototype, using Terapet’s proprietary detectors. In particular, the reduction of DOI artefacts was of interest.
Method
The NEMA NU-2 performance tests were conducted at the Department of Nuclear Medicine at Inselspital, Bern, Switzerland. Additionally, the spatial resolution test was performed in one of the clinic’s PET scanners with pixelated crystals, at the same positions relative to the edge of the FOV as in the prototype to isolate the performance difference of the detector technologies in similar geometrical configurations.
Results
The prototype achieved a FWHM of 2.56, 2.60 and 2.96 mm at 10, 100 and 200 mm radial offset, respectively. The clinical PET scanner achieved a FWHM of 3.42, 3.86 and 4.14 mm at equivalent positions. Hence, the resolution improved up to 33% in the prototype.
The prototype in its current configuration has a low detection sensitivity. This is explained by the short axial field-of-view of the prototype, the narrow energy window and restrictive coincidence-selection policy to reject scattered and random events.
The image quality assessment has not yet been completed, as the image reconstruction algorithm is undergoing further optimization before final analysis.
Conclusions
The prototype achieved the goal of demonstrating improved spatial resolution with the proprietary detectors. In particular, the spatial resolution is maintained with increasing radial offset. Future work will be aimed at improving the image reconstruction algorithms and correction methods. Construction of the full field-of-view Nuclyscan scanner using the same proprietary detectors is ongoing.
| Track | TBPET |
|---|---|
| Presentation type | Oral |