Positron emission tomography (PET) is an important imaging modality in both clinical usage and research studies. We have developed a compact high-sensitivity PET system that consisted of two large-area panel PET detector heads, which produce more than 224 million lines of response and thus request dramatic computational demands. In this work, we employed a state-of-the-art graphics processing unit (GPU), NVIDIA Tesla C2070, to yield an efficient reconstruction process. Our approaches ingeniously integrate the distinguished features of the symmetry properties of the imaging system and GPU architectures, including block/warp/thread assignments and effective memory usage, to accelerate the computations for ordered subset expectation maximization (OSEM) image reconstruction. The OSEM reconstruction algorithms were implemented employing both CPU-based and GPU-based codes, and their computational performance was quantitatively analyzed and compared. The results showed that the GPU-accelerated scheme can drastically reduce the reconstruction time and thus can largely expand the applicability of the dual-head PET system.
Precise quantitative delineation of tumor hypoxia is essential in radiation therapy treatment planning
to improve the treatment efficacy by targeting hypoxic sub-volumes.
We developed a combined imaging system of positron emission tomography (PET) and
electron para-magnetic resonance imaging (EPRI) of molecular oxygen
to investigate the accuracy of PET imaging in assessing tumor hypoxia.
The PET/EPRI combined imaging system aims to use EPRI to precisely measure the oxygen partial pressure in tissues.
This will evaluate the validity of PET hypoxic tumor imaging
by (near) simultaneously acquired EPRI as ground truth.
The combined imaging system was constructed
by integrating a small animal PET scanner (inner ring diameter 62 mm and axial field of view 25.6 mm)
and an EPRI subsystem (field strength 25 mT and resonant frequency 700 MHz).
The compatibility between the PET and EPRI subsystems were tested with both phantom and animal imaging.
Hypoxic imaging on a tumor mouse model using 18F-fluoromisonidazole radio-tracer
was conducted with the developed PET/EPRI system.
We report the development and initial imaging results obtained from the PET/EPRI combined imaging system.
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