量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum and Radiological Science and Technology.
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We are developing a PET system integrated with a birdcage RF coil for the PET-MRI. The proposed integrated system is intended to realize a convenient and highly sensitive PET system for simultaneous measurements. The integrated system can be easily replaced to other RF coils for other MRI study. In addition, a small ring diameter of the PET is applied for high sensitivity. In the presented system, PET detectors are placed close to the objective to achieve high sensitivity. Each element of the RF coil is inserted between scintillation crystal blocks inside of the shielding material. We carried out a feasible study for the PET detector integrated with the bird cage RF coil.
The prototype PET detector consisted of a LGSO crystal (Hitachi Chemical) and a multi-pixel photon counter array (S11064 series, Hamamatsu Photonics K.K.). The detector and its electrical circuit were packaged in an aluminum shielding box. Experiments were carried out with 1.5T MRI (Phillips, INTERA 1.5T Master) and a birdcage type RF-coil. The shielding boxes, with the detector and circuit, were placed in the gap of the RF-coils. In order to reduce noise contamination from outside the MRI room, a band pass filter was applied on the power line of the MPPC. First, influence on the PET detector from MRI was evaluated by comparing energy spectra obtained before and during MRI measurement. Simultaneously, influences on the MRI image from the PET detector were evaluated. Next, the influences of the shielding material for the PET detectors on the magnetic field and RF pulse of MRI were evaluated. Dummy detectors which were simply copper shielding boxes were placed at all gaps of the RF coil and MRI images were evaluated.
As a result, the PET detector worked in simultaneous measurements the same as it did when the MRI was not operated. The MRI images also were obtained as usual even though the PET detector and the shielding materials was positioned close to the RF coil.
Feasibility study for a PET detector integrated with a RF coil for PET-MRI
