A compact and high sensitivity positron detector using dual-layer thin GSO scintillators for a small animal PET blood sampling system

Seiichi Yamamoto*, Masao Imaizumi, Eku Shimosegawa, Yasukazu Kanai, Yusuke Sakamoto, Kotaro Minato, Keiji Shimizu, Michio Senda, Jun Hatazawa

*この研究の対応する著者

研究成果: Article査読

8 被引用数 (Scopus)

抄録

For quantitative measurements of small animals such as mice or rats, a compact and high sensitivity continuous blood sampling detector is required because their blood sampling volume is limited. For this purpose we have developed and tested a new positron detector. The positron detector uses a pair of dual-layer thin gadolinium orthosilicate (GSO) scintillators with different decay times. The front layer detects the positron and the background gamma photons, and the back layer detects the background gamma photons. By subtracting the count rate of the latter from that of the former, the count rate of the positrons can be estimated. The GSO for the front layer has a Ce concentration of 1.5 mol% (decay time of 35 ns), and that for the back layer has a Ce concentration of 0.5 mol% (decay time of 60 ns). By using the pulse shape analysis, the count rate of these two GSOs can be discriminated. The thickness is 0.5 mm, which is thick enough to detect positrons while minimizing the detection of the background gamma photons. These two types of thin GSOs were optically coupled to each other and connected to a metal photomultiplier tube (PMT) through triangular light guides. The signal from the PMT was digitized by 100 MHz free-running A-D converters in the data acquisition system and digitally integrated at two different integration times for the pulse shape analysis. We obtained good separation of the pulse shape distributions of these two GSOs. The energy threshold level was decreased to 80 keV, increasing the sensitivity of the detector. The sensitivity of a small diameter plastic tube was 8.6% and 24% for the F-18 and C-11 positrons, respectively. The count rate performance was linear up to ∼50 kcps. The background counts from the gamma photons could be precisely corrected. The time-activity curve (TAC) of the rat artery blood was successfully obtained and showed a good correlation with that measured using a well counter. With these results, we confirmed that the developed blood sampling detector is promising for quantitative measurement for an animal positron emission tomography system.

本文言語English
ページ(範囲)3813-3826
ページ数14
ジャーナルPhysics in Medicine and Biology
55
13
DOI
出版ステータスPublished - 2010
外部発表はい

ASJC Scopus subject areas

  • 放射線技術および超音波技術
  • 放射線学、核医学およびイメージング

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