WSF gamma camera with SiPMs: First small animal tests

• Published in: 2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC) pp. 1 - 6
• Main Authors: Castro, I. F., Soares, A. J. D., Moutinho, L. M., Ferreira, M. A., Ferreira, R., Combo, A., Muchacho, F., Santos, A. C., Veloso, J. F. C. A.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.10.2013
• Subjects: Bones; Cameras; Crystals; Energy resolution; Prototypes; Spatial resolution
• ISSN: 1082-3654; 2577-0829
• DOI: 10.1109/NSSMIC.2013.6829099

Following the introduction of the wavelength-shifting fiber (WSF) gamma camera by Soares et al. and evolution of photodiodes into highly sensitive silicon photomultipliers (SiPMs), we have assembled a WSF gamma camera applying SiPMs to individually read out 1 mm diameter WSFs carrying the position information of scintillation events in a continuous CsI(Na) crystal. Despite the challenge of using many SiPMs to read out light pulses of very low amplitude and slow decay time, at room-temperature, SiPMs show great potential to improve the spatial resolution and overall performance of the WSF gamma camera, due to their high photodetection efficiency. Moreover, they allow building a compact and low power consuming camera, aimed for breast-specific gamma imaging. Tests carried out with 57 Co and 99 mTc on a small prototype with 10×10 mm 2 field-of-view demonstrated the concept's feasibility and characterized its imaging performance. A larger camera with 10×10 cm 2 is being developed for clinical application, but isn't yet fully operational. Imaging of a small mouse injected with 99m Tc-HMDP was therefore carried out by performing several scans with the small prototype. Despite experimental limitations, the resulting images compared favorably to those obtained by a traditional Anger camera. Furthermore, performance can be improved by several optimizations, in order to minimize and control effects of thermal noise and non-uniformity of response of multiple SiPMs.