@article{oai:junshin.repo.nii.ac.jp:00000321,
 author = {谷, 拓弥 and 河村, 誠治 and 池末, 竜治 and 松竹, 裕紀 and 川田, 秀道 and 倉田, 精二 and TANI, Takuya and KAWAMURA, Seiji and IKEMATSU, Ryuji and MATSUTAKE, Yuki and KAWATA, Hidemichi and KURATA, Seiji},
 issue = {11},
 journal = {純真学園大学雑誌, Journal of Junshin Gakuen University,Faculty of  Health Sciences},
 month = {Mar},
 note = {application/pdf, Discovery MI (DMI) は, 世界初の光センサーに半導体光電子増倍機器 (SiPM) を搭載したPET/CTである. PETの画質は, 体格が大きい被検者は, 体重あたりの18F-FDGの投与量を5MBq/kgを上限に, できるだけ多く投与することにより画質が向上するとされてきた. これらの報告は, 光電子増倍管 (PMT) を搭載したPET/CTを使用しており, SiPMを搭載したDMIにおいて体格がPET画像の画質評価指標である肝SNRに及ぼす影響を評価した報告は見られない. 本研究の目的は, DMIによるFDG-PET検査を受けた患者の臨床画像を解析し, PET画像の画質と被検者固有の因子である体格との関係ついて検討することである.  
対象は, DMIでFDG-PET検査を施行した91例とした. 肝SNRと患者固有の因子である体重等との間でそれぞれの相関係数を算出し, それらの関係の検討を行った. またDMIと従来の検出器 (BGO) を搭載したPET/CTであるDiscovery ST Elite (DST) から得られた肝SNRの比較を行った. 
DMIでは, 体重が30～90㎏の間で肝SNRは15.26 ± 2.16で推移した. 肝SNRの値は, 体重, BMI, 断面積の増加による影響を殆ど受けなかった. 投与量の増加および身長が高くなるにつれ肝SNRは若干増加する傾向を示した. 一方, DSTから得られた肝SNRは殆どの症例で「がんFDG-PET/CT撮像法ガイドライン」に示された10より小さな値を示した. 以上からDMIの画像は安定した非常に優れた画像であると考えられた.
DMIの画像が高画質である要因は, SiPMの使用でPMTの2倍の光検出効率があること, コンプトン散乱リカバリーの採用やtime-of-flight (TOF) の時間分解能が390psと良くなりTOFの効果が発揮できコントラストや感度が良くなったことが挙げられる. 　　　　　　  
SiPMを搭載したDMIの画像は, 従来はPET画像の画質を左右した体重, 身長, BMI, 投与量, 断面積の影響を大きく受けず安定した高画質であることが確認できた., Discovery MI (DMI) is the world’s first positron emission tomography (PET)/computed tomography (CT) scanner equipped with a silicon photomultiplier (SiPM) as a photosensor. Moreover, for individuals with a fine physique, PET image quality has been reported to improve with higher F-fluorodeoxyglucose (F-FDG) dosages per unit of body weight18 with an upper limit of 5 MBq/kg. PET/CT equipped with a photomultiplier tube (PMT) was used for such reports. However, the impact of physical size on the liver signal-to-noise ratio (SNR), which is an image quality assessment index for PET imaging with DMI and SiPM, has not been reported previously. The purpose of this study was to analyze the clinical images of patients undergoing FDG-PET testing with DMI and to discuss the relationship between PET image quality and patients’ physical size, which is an inherent factor for individual patients.
This study included 91 patients who underwent FDG-PET with DMI. Individual coefficients of correlation between the liver SNR and the patient’s unique factors, including body weight, were calculated and reviewed. A comparison of liver SNRs obtained by DMI and Discovery ST Elite (DST), a PET/CT scanner equipped with a conventional detection unit, was also conducted.
The mean liver SNR with DMI was 15.26 ± 2.16, with body weights of 30–90 kg. Liver SNR values were not altered by increases in body weight, body mass index (BMI), or cross-sectional area. Liver SNRs tended to be slightly higher with increased dosage and height. Moreover, liver SNRs obtained by DST were less than 10, which is a reference specified in the Cancer FDG-PET/CT Imaging Procedure Guidelines in most cases. Therefore, DMI delivers stable and superior images.
As factors of the superior image quality of DMI, twice as high photodetection efficiency as PMT provided by the use of SiPM, better contrast and sensitivity from the greater time-of-flight (TOF) effects with the employment of Compton scatter recovery, and TOF temporal resolution as good as 390 ps were identified.
Images by DMI equipped with SiPM were confirmed to be stable and of high quality without a significant impact on body weight, height, BMI, dosage, and cross-section area, which largely affects the conventional PET image quality.},
 pages = {99--110},
 title = {【原著】半導体光電子増倍器 (SiPM) 搭載のPET/CTにおける 肝SNRを用いたPET画像に関する研究},
 year = {2021},
 yomi = {タニ, タクヤ and カワムラ, セイジ and イケマツ, リュウジ and マツタケ, ユウキ and カワタ, ヒデミチ and クラタ, セイジ}
}