2026-08-06 東京大学
陽電子3光子崩壊による次世代核医学検査のイメージ図
＜関連情報＞
- https://www.t.u-tokyo.ac.jp/press/pr2026-08-06-002
- https://www.nature.com/articles/s42005-026-02782-6
純粋な陽電子放出体を用いた三光子崩壊の直接イメージングによるPETの進歩 Advancing PET through direct imaging of three-photon decay using pure positron emitters
Macoto Fujimoto,Riku Sato,Moh Hamdan,Mizuki Uenomachi,Peter Caradonna,Laura Stephenson,Archie Montgomery,Julien Bordes,James R. Brown,Daniel P. Watts & Kenji Shimazoe
Communications Physics Published:06 August 2026
DOI:https://doi.org/10.1038/s42005-026-02782-6
Abstract
Positronium is abundantly formed inside the human body during positron emission tomography (PET). Its properties, such as lifetime and three-photon decay rate, are highly sensitive to the microenvironment, particularly oxygen partial pressure and the size of free voids. Thus, positronium is a promising biomarker for an imaging modality complementary to conventional PET imaging. Here we achieved positronium ratio imaging through the direct localization of three-photon annihilation events. The first image of the three-to-two-photon decay ratio was obtained using high-resolution scintillation detectors and a standard radiotracer, yielding results highly consistent with positronium lifetime studies. A spatial resolution of sub-1.1 cm is achieved in both experimental and simulated data without relying on tomographic reconstruction or time-of-flight information. This technique provides additional information about tissue hypoxia or morphology, offering potential for improved early diagnosis.
