Recent progress of MPPC-based scintillation detectors in high precision X-ray and gamma-ray imaging

J. Kataoka*, A. Kishimoto, T. Fujita, T. Nishiyama, Y. Kurei, T. Tsujikawa, T. Oshima, T. Taya, Y. Iwamoto, H. Ogata, H. Okochi, S. Ohsuka, H. Ikeda, S. Yamamoto

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)


The multi-pixel photon counter (MPPC) is a promising light sensor for various applications, not only in physics experiments but also in nuclear medicine, industry, and even high-energy astrophysics. In this paper, we present the current status and most recent progress of the MPPC-based scintillation detectors, such as (1) a high-precision X-ray and gamma-ray spectral image sensor, (2) next-generation PET detectors with MRI, TOF, and DOI measurement capabilities, and (3) a compact gamma camera for environmental radiation surveys. We first present a new method of fabricating a Ce:GAGG scintillator plate (1 or 2 mm thick) with ultra-fine resolution (0.2 mm/pixel), cut using a dicing saw to create 50μm wide micro-grooves. When the plate is optically coupled with a large-area MPPC array, excellent spatial resolution of 0.48 mm (FWHM) and energy resolution of 14% (FWHM) are obtained for 122 keV gamma rays. Hence, the detector can act as a convenient "multi-color" imaging device that can potentially be used for future SPECT and photon-counting CT. We then show a prototype system for a high-resolution MPPC-based PET scanner that can realize 1 mm (FWHM) spatial resolution, even under a strong magnetic field of 4.7 T. We develop a front-end ASIC intended for future TOF-PET scanner with a 16-channel readout that achieves a coincidence time resolution of 489 ps (FWHM). A novel design for a module with DOI-measurement capability for gamma rays is also presented by measuring the pulse height ratio of double-sided MPPCs coupled at both ends of scintillation crystal block. Finally, we present the concept of a two-plane Compton camera consisting of Ce:GAGG scintillator arrays coupled with thin MPPC arrays. As a result of the thin and compact features of the MPPC device, the camera not only achieves a small size (14×14×15 cm3) and light weight (1.9 kg) but also excellent sensitivity, compared to the conventional PMT-based pinhole camera used in Fukushima. Finally, we briefly describe a new product recently developed in conjunction with Hamamatsu Photonics K.K. that offers improved sensitivity and angular resolution of Δθ-8° (FWHM) at 662 keV, by incorporating DOI-segmented scintillator arrays.

Original languageEnglish
Pages (from-to)248-254
Number of pages7
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Publication statusPublished - 2015 Jun 1


  • Compton camera
  • Multi-pixel photon counter (MPPC)
  • Next generation PET
  • Scintillator

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


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