Seiichi Yamamoto

A Geiger-mode avalanche photodiode (Si-PM) is a promising photodetector for PET, especially for use in a magnetic resonance imaging (MRI) system, because it has high gain and is less sensitive to a static magnetic field. We developed a Si-PM-based depth-of-interaction (DOI) PET system for small animals. Hamamatsu 4 × 4 Si-PM arrays (S11065-025P) were used for its detector blocks. Two types of LGSO scintillator of 0.75 mol% Ce (decay time: ∼45 ns; 1.1 mm × 1.2 mm × 5 mm) and 0.025 mol% Ce (decay

The authors have developed a GSO depth of interaction detector. Three GSO scintillators with different concentration of Ce were chosen and stacked along depth of interaction direction and optically coupled to a photomultiplier tube (PMT) or a position sensitive photomultiplier tube (PSPMT). Pulse shape, light output and zero-cross time were measured to select a proper combination of GSO scintillators with different concentration of Ce. Selecting 3 GSO scintillators with different concentration o

Luminescence imaging during carbon-ion irradiation of water is not only possible but also a promising method for range estimation in carbon-ion therapy.

We investigated the magnetic susceptibility of several scintillators to select the best material for MR-compatible gamma detectors. NaI(Tl) in an Al container, NaI(Tl) in a Cu container and CsI(Tl) are candidates for MR-compatible gamma probes, imaging probes or SPECT, while BGO, LSO, LGSO, and GSO are the candidates for MR-compatible PET. In addition, we investigated image artifacts and distortion by scanning these scintillators with an MR-scanner. Results show that the magnetic susceptibility

Brain functional studies using PET have advantages over fMRI in some areas such as auditory research in part because PET systems produce no acoustic noise during acquisition. However commercially available PET systems are designed for whole body studies and are not optimized for brain functional studies. We developed a low cost, small, wearable brain PET system named PET-Hat dedicated for brain imaging. It employs double counter-balanced systems for mechanical supports of the detector ring while

Since a high resolution PET system is needed for small animal imaging, especially for mouse studies, we developed a new small animal PET system that decreased the size of the scintillators to less than 1 mm. Our developed PET system used 0.5 × 0.7 × 5 mm(3) LYSO pixels arranged in an 11 × 13 matrix to form a block with a 0.1 mm BaSO4 reflector between the pixels. Two LYSO blocks were optically coupled to two optical fiber based angled image guides. These LYSO blocks and image guides were coupled

Purpose: The authors previously reported successful luminescence imaging of water during proton irradiation and its application to range estimation. However, since the feasibility of this approach for carbon-ion irradiation remained unclear, the authors conducted luminescence imaging during carbon-ion irradiation and estimated the ranges. Methods: The authors placed a pure-water phantom on the patient couch of a carbon-ion therapy system and measured the luminescence images with a high-sensitivi

The silicon-photomultiplier (Si-PM) is a promising photodetector, especially for integrated PET/MRI systems, due to its small size, high gain, and low sensitivity to static magnetic fields. The major problem using a Si-PM-based PET system within the MRI system is the interference between the PET and MRI units. We measured the interference by combining a Si-PM-based PET system with a permanent-magnet MRI system. When the RF signal-induced pulse height exceeded the lower energy threshold level of

The silicon photomultiplier (Si-PM) is a promising photo-detector for PET for use in magnetic resonance imaging (MRI) systems because it has high gain and is insensitive to static magnetic fields. Recently we developed a Si-PM-based depth-of-interaction PET system for small animals and performed simultaneous measurements by combining the Si-PM-based PET and the 0.15 T permanent MRI to test the interferences between the Si-PM-based PET and an MRI. When the Si-PM was inside the MRI and installed a