Development of a high-resolution Si-PM-based gamma camera system

Seiichi Yamamoto*, Hiroshi Watabe, Yasukazu Kanai, Masao Imaizumi, Tadashi Watabe, Eku Shimosegawa, Jun Hatazawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


A silicon photomultiplier (Si-PM) is a promising photodetector for PET, especially for PET/MRI combined systems, due to its high gain, small size, and lower sensitivity to static magnetic fields. However, these properties are also promising for gamma camera systems for single-photon imaging. We developed an ultra-high-resolution Si-PM-based compact gamma camera system for small animals. Y2SiO5:Ce (YSO) was selected as scintillators because of its high light output and no natural radioactivity. The gamma camera consists of 0.6 mm × 0.6 mm × 6 mm YSO pixels combined with a 0.1 mm thick reflector to form a 17 × 17 matrix that was optically coupled to a Si-PM array (Hamamatsu multi-pixel photon counter S11064-050P) with a 2 mm thick light guide. The YSO block size was 12 mm × 12 mm. The YSO gamma camera was encased in a 5 mm thick gamma shield, and a parallel hole collimator was mounted in front of the camera (0.5 mm hole, 0.7 mm separation, 5 mm thick). The two-dimensional distribution for the Co-57 gamma photons (122 keV) was almost resolved. The energy resolution was 24.4% full-width at half-maximum (FWHM) for the Co-57 gamma photons. The spatial resolution at 1.5 mm from the collimator surface was 1.25 mm FWHM measured using a 1 mm diameter Co-57 point source. Phantom and small animal images were successfully obtained. We conclude that a Si-PM-based gamma camera is promising for molecular imaging research.

Original languageEnglish
Pages (from-to)7555-7567
Number of pages13
JournalPhysics in Medicine and Biology
Issue number23
Publication statusPublished - 2011 Dec 7
Externally publishedYes

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging


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