Commissioning and Characterization of a High-Sensitivity Bgo-Based Digital PET/CT for Radiation Therapy Applications
Abstract
Purpose
Positron Emission Tomography/Computed Tomography (PET/CT) plays a pivotal role in radiation therapy, particularly in tumor delineation, response assessment, and adaptive therapy planning. However, the reliability of PET/CT depends on key system performance and QA metrics. This study evaluates the performance characteristics of a GE-Omni-Legend PET/CT system and its auxiliary equipment for radiation therapy applications.
Methods
PET subsystem of the Omni Legend-32 was evaluated using NEMA NU 2-2018 standards, the AAPM TG-126 report, and ACR guidelines. The CT subsystem was tested for CT number accuracy, field uniformity, electron density-to-CT number convesrion, spatial resolution, and image quality using the AAPM TG-66 report. Laser and MapRT QA procedures were evaluated and commissioned. Image quality and quantitative accuracy were analyzed under clinically relevant acquisition protocols.
Results
NEMA-based radial and tangential spatial resolution ranged from 3.73 mm at the center of the field of view to 4.23 mm at a radial offset of 20 cm, and from 3.95 mm to 7.72 mm at the same offset, respectively. A peak NECR of 478.1 kcps at 16.7 kBq/ml and a scatter fraction of 35.76% were measured. Total system sensitivity was 47.58 cps/kBq at the center and 45.86 cps/kBq at a 10 cm offset. Contrast recovery coefficients (CRCs) for hot spheres ranged from 0.49 to 0.89, depending on sphere size. The average lung residual error was 11.6%. CT-to-PET registration accuracy was within 3 mm. Deep learning-based non-time-of-flight to time-of-flight enhancement produced high-contrast images. Measured CT subsystem results were within acceptance criteria. Laser alignment was within 2 mm, and MapRT collision checks showed gantry angle accuracy within 1 degree.
Conclusion
The performance of the GE Omni Legend-32 PET/CT system and its auxiliary equipment was evaluated against standard clinical benchmarks and demonstrates that the system offers high sensitivity and counting performance, making it well-suited for PET-guided radiation therapy applications.