Virtual PMTs: improving centroid positioning performance near the edges of a gamma camera detector
| Autor: | Paul Vaska, Michael J. Petrillo, Gerd Muehllehner |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Physics
Nuclear and High Energy Physics medicine.medical_specialty Photomultiplier Physics::Instrumentation and Detectors business.industry Detector Centroid Iterative reconstruction Signal Particle detector law.invention Nuclear Energy and Engineering law medicine Medical physics Computer vision Artificial intelligence Electrical and Electronic Engineering business Image resolution Gamma camera |
| Zdroj: | IEEE Transactions on Nuclear Science. 48:645-649 |
| ISSN: | 1558-1578 0018-9499 |
| DOI: | 10.1109/23.940140 |
| Popis: | The radiation detector used in typical gamma cameras and NaI-based positron emission tomography (PET) scanners effectively positions events over most of its crystal area, but the spatial resolution begins to suffer at the edges. One reason is that the measured light distribution is truncated or otherwise asymmetric, and the centroid positioning algorithm no longer optimally weights the photomultiplier tube (PMT) signals in this case. As a result, events less than a certain distance from the edge must be rejected, reducing geometric efficiency and complicating image reconstruction for PET systems with multiple fixed detectors. Short of discarding the centroid algorithm altogether, a computationally simple way to improve the positioning is to define a strip of physically nonexistent, or virtual, PMTs around the actual PMTs and to assign realistic signal values to them event by event based on the signals of nearby real PMTs. If the centroid algorithm now also includes the virtual PMTs, improved spatial resolution is obtained due to better weighting of the PMT signals. With minimal modification to the detector, the virtual PMT method was implemented and tested on an ADAC UGM C-PET detector and found to significantly improve spatial resolution near the detector edges. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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