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Program Information

Design and Development of a High Resolution Onboard PET for Integrated PET/CT Animal Irradiator

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Y Shao

Y Shao*, Y Zhong , X Cheng , J Wang , UT Southwestern Medical Center, Dallas, TX


SU-E-FS1-3 (Sunday, July 30, 2017) 1:00 PM - 1:55 PM Room: Four Seasons 1

Purpose: To design and develop an onboard PET integrated into an existing animal irradiator to enable streamlined PET/CT image-guided animal (mouse and rat) x-ray radiotherapy for translational researches.

Methods: Each detector consists of a 16x16 array of 1x1x20 mm LYSO scintillators, with each array end optically coupled to an 8x8 array of 2x2 mm Silicon Photomultipliers. Scintillator surface has desired surface roughness for enhancing the depth-of-interaction (DOI) measurement. PET consists of 2 rings of modular detectors in a stationary multi-polygon configuration. The trans-axial and axial FOVs are 80 and 30 mm for rat imaging. PET performances were investigated with: 1) simulated images of a Na-22 point source at different field-of-view positions to measure the resolution and uniformity; 2) simulated images of a F-18 hot-rod phantom with 0.75 to 2.0 mm rod diameters; 3) simulated F18-FDG PET and CT images of a digital rat phantom with a ~6 mm tumor to investigate the PET/CT IGRT. In addition, initial detector design studies were conducted.

Results: Without further image data processing and correction, the simulation study shows ~0.6 mm resolutions among all directions at the FOV center, and <1.0 mm for up to ~40 mm diameter with 5.0 mm DOI resolution. All hot-rods can be clearly identified from reconstructed images, including 0.75 mm ones. System sensitivity is ~4% across FOV. Simulated PET/CT images show clear tumor delineation for accurate target definition (3:1 tumor/background activity ratio). Consequently, the first detector has been constructed according to this design and is currently under evaluation.

Conclusion: These initial studies indicate that the targeted high and uniform PET image resolutions can be achieved using latest SiPM arrays and DOI measurable detector design, which will lead the further development to achieve first integrated PET/CT/RT system for streamlined functional/anatomic image-guided preclinical RT applications.

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