Development of a prototype Open-close positron emission tomography system.
We developed a prototype positron emission tomography (PET) system based on a new concept called Open-close PET, which has two modes: open and close-modes. In the open-mode, the detector ring is separated into two halved rings and subject is imaged with the open space and projection image is formed. In the close-mode, the detector ring is closed to be a regular circular ring, and the subject can be imaged without an open space, and so reconstructed images can be made without artifacts. The block detector of the Open-close PET system consists of two scintillator blocks that use two types of gadolinium orthosilicate (GSO) scintillators with different decay times, angled optical fiber-based image guides, and a flat panel photomultiplier tube. The GSO pixel size was 1.6 × 2.4 × 7 mm and 8 mm for fast (35 ns) and slow (60 ns) GSOs, respectively. These GSOs were arranged into an 11 × 15 matrix and optically coupled in the depth direction to form a depth-of-interaction detector. The angled optical fiber-based image guides were used to arrange the two scintillator blocks at 22.5° so that they can be arranged in a hexadecagonal shape with eight block detectors to simplify the reconstruction algorithm. The detector ring was divided into two halves to realize the open-mode and set on a mechanical stand with which the distance between the two parts can be manually changed. The spatial resolution in the close-mode was 2.4-mm FWHM, and the sensitivity was 1.7% at the center of the field-of-view. In both the close- and open-modes, we made sagittal (y-z plane) projection images between the two halved detector rings. We obtained reconstructed and projection images of (18)F-NaF rat studies and proton-irradiated phantom images. These results indicate that our developed Open-close PET is useful for some applications such as proton therapy as well as other applications such as molecular imaging.
Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Seiichi
S
Yamamoto
Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Satoshi
S
Okumura
Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka, Japan.
Tadashi
T
Watabe
Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka, Japan.
Hayato
H
Ikeda
Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka, Japan.
Yasukazu
Y
Kanai
Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan.
Toshiyuki
T
Toshito
Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Masataka
M
Komori
Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Yoshimune
Y
Ogata
Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Katsuhiko
K
Kato
Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka, Japan.
Jun
J
Hatazawa
D000818:Animals; D002138:Calibration; D004867:Equipment Design; D007091:Image Processing, Computer-Assisted; D008297:Male; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D011522:Protons; D051381:Rats; D017207:Rats, Sprague-Dawley
D011522:Protons