@article{oai:repo.qst.go.jp:00080098,
 author = {Yoshida, Eiji and Tashima, Hideaki and Nagatsu, Kotaro and Tsuji, Atsushi and Kamada, Kei and Parodi, Katia and Yamaya, Taiga and Yoshida, Eiji and Tashima, Hideaki and Nagatsu, Kotaro and Tsuji, Atsushi and Parodi, Katia and Yamaya, Taiga},
 issue = {12},
 journal = {Physics in Medicine & Biology},
 month = {Jun},
 note = {We proposed a concept of whole gamma imaging (WGI) that utilizes all detectable gamma rays for imaging. An additional detector ring, which is used as the scatterer, is inserted in the field-of-view of a PET ring so that single gamma rays can be detected by the Compton imaging method. In particular, for the non-pure positron emitters which emit an additional gamma ray almost at the
same time, triple gamma imaging will be enabled; localization on each line-of-response (LOR) is possible by using the Compton cone of the additional gamma ray. We developed a prototype to show a proof of the WGI concept. The diameters of scatterer ring and PET ring were set as 20 cm and 66 cm, respectively. For Compton imaging of the 662-keV gamma ray from a 137Cs point source, spatial resolution obtained by the list-mode OSEM algorithm was 4.4 mm FWHM at the 8 cm off-center position and 13.1 mm FWHM at the center position. For PET imaging of a 22Na point source, spatial resolution was about 2 mm FWHM at all positions. For the triple gamma imaging, 5.7 mm FWHM (center) and 4.8 mm FWHM (8 cm off-center) were obtained for the
22Na point source just by plotting the intersecting points between each LOR and each Compton cone of the 1275-keV gamma ray. No image reconstruction was applied. Scandium-44 was produced as a practical candidate of the non-pure positron emitters, and 6.6 mm FWHM (center) and 5.8 mm FWHM (8 cm off-center) were obtained in the same manner. This direct imaging approach which neither requires time-consuming event integration nor iterative image
reconstruction may allow in vivo real-time tracking of a tiny amount of activity. Our initial results showed the feasibility of the WGI concept, which is a novel combination of PET and Compton imaging.},
 pages = {125013-1--125013-15},
 title = {Whole gamma imaging: a new concept of PET combined with Compton},
 volume = {65},
 year = {2020}
}