Temperature dependence of APD-based PET scanners.
Vincent Keereman1, Roel Van Holen, Stefaan Vandenberghe
1MEDISIP, Department of Electronics and Information Systems, Ghent University-iMinds-IBiTech, De Pintelaan 185, B-9000 Ghent, Belgium. Vincent.Keereman@ugent.be
Medical Physics
|September 7, 2013
Summary
Stable ambient temperatures are crucial for accurate results in avalanche photodiode (APD) PET imaging. Performance metrics like sensitivity and count rate are highly temperature-dependent, while spatial resolution remains unaffected.
Area of Science:
- Medical Imaging
- Nuclear Physics
- Biomedical Engineering
Background:
- Avalanche photodiodes (APDs) are increasingly used in Positron Emission Tomography (PET) detectors.
- APD gain and scintillation crystal light yield decrease with rising ambient temperature, impacting PET scanner performance.
- This temperature dependence necessitates modeling and evaluation for APD-based PET systems.
Purpose of the Study:
- To propose and validate a model for the temperature dependence of APD-based PET scanners.
- To evaluate the performance of the LabPET8 small animal PET scanner across different temperatures.
- To assess the impact of temperature fluctuations on key performance metrics.
Main Methods:
- Developed a model predicting temperature-induced compression of the energy histogram.
- Acquired energy histograms at 21°C and 25°C to validate the model.
- Simulated and experimentally measured system sensitivity, axial sensitivity profile, spatial resolution, scatter fraction, and count rate performance at various temperatures.
Main Results:
- The model accurately predicted a ~6% per °C shift in photopeak energy with increasing temperature.
- System sensitivity showed a strong linear decrease with temperature (10-12% per °C).
- While peak total count rates were similar, peak true count rates were higher at elevated temperatures, but with increased scatter and random coincidences.
Conclusions:
- System sensitivity and count rate performance are significantly affected by ambient temperature in APD-based PET scanners.
- System spatial resolution is not temperature-dependent.
- Maintaining stable ambient temperatures is essential for reproducible imaging results with APD-based PET scanners.
