The development and performance of UV-enhanced APD-arrays for high resolution PET imaging coupled with pixelized Pr:LuAG crystal

M. Yoshino*, J. Kataoka, T. Nakamori, H. Matsuda, T. Miura, T. Katou, Y. Ishikawa, N. Kawabata, Y. Matsunaga, K. Kamada, Y. Usuki, A. Yoshikawa, T. Yanagida

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


The development of high-resolution, UV-enhanced avalanche photodiode (APD) arrays usable in high-resolution PET imaging is underway. These APD arrays were specifically designed as photosensors capable of direct coupling with pixelized Pr-doped Lu3Al5O12 (Pr:LuAG) scintillators. An excellent quantum efficiency (QE) of 55% was achieved at the peak emission of Pr:LuAG (310 nm), namely, a substantial improvement from the QE ≤5% as measured with the conventional Hamamatsu reverse-type APDs (S8664 series). Each APD device has 8×8 (TYP1) and 12×12 (TYP2) pixel structures with active areas of 3×3 mm2 and 2×2 mm2 in each pixel, respectively. A gain uniformity of ±8% and low dark noise of ≤2nA/pixel have been achieved, measured at 25 °C. We also report on the large size single crystal growth of improved Pr:LuAG scintillators and the preliminary performance test of the same. An energy resolution of 4.2% (FWHM) was obtained for 662 keV gamma-rays for 10×10×10 mm3 crystal, measured with a PMT employing a super-bialkali photocathode. We made a test module consisting of a UV-enhanced APD-array (either TYP1 or TYP2) optically coupled with an 8×8 (or 12×12) pixel Pr:LuAG matrix. The linearity between the output signals and incident gamma-ray energy of TYP1 and TYP2 gamma-ray detectors were only 0.27 and 0.33%, as measured at 25 °C for various gamma-ray sources, respectively. Energy resolutions of 7.0±0.2% (FWHM) and 9.0±0.6% (FWHM) were, respectively, obtained for TYP1 and TYP2 detector arrays for 662 keV gamma-rays. The uniformity of the pulse height distributions was also measured at less than 8% for both detectors. Finally, we measured the coincidence timing resolution of these gamma-ray detectors and obtained 4.0±0.1 ns (FWHM) for the 511 keV annihilation quanta from a 22Na source. These results suggest that UV-enhanced APD-arrays coupled with Pr:LuAG scintillators could be a promising device for future application in nuclear medicine.

Original languageEnglish
Pages (from-to)57-63
Number of pages7
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Issue number1
Publication statusPublished - 2011 Jul 1


  • Avalanche photodiode
  • Gamma-rays
  • Positron emission tomography

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


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