UC Davis Biomedical Engineering

Felipe Godinez Receives 2012 IEEE-NPSS Student Paper Award

Biomedical Engineering Ph.D. student Felipe Godinez has won a 2012 IEEE-NPSS Student Paper Award. This award is given to an outstanding student oral or poster paper presented at the Nuclear Science Symposium, Medical Imaging Conference of the Nuclear & Plasma Sciences Society. Felipe won for, “pawPET: a High Sensitivity, High Resolution PET Scanner for Rodent Paws.” The paper describes a new PET scanner capable of high resolution, high molecular sensitivity imaging of rodent paws to study arthritis and other conditions.  The project was developed and manufactured within the Biomedical Engineering Department’s TEAM Design, Prototyping, and Fabrication Laboratories.

The NSS and MIC each awarded two papers. Each paper received a cash award of $500 and a certificate. The purpose of these awards is to encourage both outstanding student contributions and greater student participation as principal or sole authors of papers as well as to acknowledge the importance of student contributions to the fields embraced by NPSS.

Felipe received a Bachelor’s Degree in Mechanical Engineering from UC Riverside and is now a Ph.D. candidate in the department of Biomedical Engineering at the University of California Davis, under the supervision of Dr. Ramsey Badawi. His thesis project is on the design, fabrication, and performance characterization of a high image resolution positron emission tomography scanning for human extremities.

pawPET: a High Sensitivity, High Resolution PET Scanner for Rodent Paws

F. Godinez 1, A. J. Chaudhari 2,Y Yang 1, J. Fung 1, R. Farrell 3, S. Kundu-Raychaudhuri 4, S. P. Raychaudhuri 4, R. D. Badawi 1,2

1Biomedical Engineering, University of California Davis, Davis, California, USA

2Radiology, University of California Davis, Davis, California, USA

3Radiation Monitoring Devices Inc., Watertown, Massachusetts, USA

4Rheumatology, University of California Davis, Davis, California, USA

We present the pawPET scanner that is capable of super-high resolution and high sensitivity molecular imaging of rodent paws. In clinical conditions like arthritis, animal models such as the collagen-induced arthritis (CIA) mouse and rat models are routinely used to study the inflammatory cascade that is a key mediator of the diseases. As a gold standard, animals are currently sacrificed at various stages in the disease cycle to perform histopathology on the paws. PET holds high potential for such studies in vivo. Commercially available PET systems for scanning small animals are suboptimal for imaging the mouse paw which may be ~4 mm in diameter with digits ~1 mm diameter. Quantification is compromised by the partial volume effect. Each PET detector is based on a 36 x 36 array of 0.44 x 0.44 x 8.0 mm^3 unpolished LSO crystals wrapped in the TORAY reflector. The array is read out in a hybrid dual-ended readout scheme by an avalanche photodiode at the animal end and a position sensitive photomultiplier tube at the opposite end. We characterized the performance of the detectors in terms of their energy and DOI resolution, and crystal identification. An automatic segmentation routine was able to identify 33 x 33 crystals of the 36 x 36 crystals in the array. The average DOI resolution across depths for a central crystal was 1.89 mm with a range of 1.49 mm – 2.30 mm. The average energy resolution across depths was 27.0% with a range of 20.9%- 35.3%. A scanner was built using two detectors as heads. The scanner can rotate the heads around the mouse paw 180 degrees about a horizontal central axis. The scanner has a 9 mm field-of-view, with detectors in close proximity of the paw to improve sensitivity. Feasibility studies by localizing the mouse paws one at a time in the scanner were completed. The scanner is scheduled to be tested on CIA mouse models.

Funding provided by NCI: R01 CA129561, F32 CA157213