Program Information
In-Beam PET Measurements of Washout in Rabbit Using 10C, 11C and 15O Ion Beams
Chie Toramatsu*12,Eiji Yoshida, Hidekazu Wakizaka 2,Akram Mohammadi 2,Hideaki Tashima 2,Fumihiko Nishikido 2,Atsuchi Kitagawa2,Taku Inaniwa2,Kumiko Karasawa 1, and Taiga Yamaya 2,(1) Tokyo Women's Medical University, (2)National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology
Presentations
WE-F-201-4 (Wednesday, August 2, 2017) 1:45 PM - 3:45 PM Room: 201
Purpose: In particle therapy, in-beam positron emission tomography (PET) is expect to enable in-situ noninvasive confirmation of the treatment delivery. For accurate range/dose verification or 3D imaging, however, correction of the biological washout effect in a living body is necessary. The final aim of this study is to establish appropriate washout modeling not only for washout correction but also tumor viability estimation. In this study, we measured the washout rate in a rabbit using recently developed oxygen beam as well as carbon beams.
Methods: To measure components of washout, three species of nuclides, ¹⁰C,¹¹C and ¹⁵O, which were generated as secondary beams, were irradiated on the rabbit brain under two conditions, live and dead. In-beam data were acquired by whole-body open type PET, which enable 3D in-beam imaging. Region of interests (ROIs) were set as a 3D positron distribution and the time activity curves (TACs) of the irradiated field were acquired. The washout rate in those conditions was obtained based on multiple component model analysis. Obtained washout rate was compared to the previous study of cereberal blood flow (CBF) measurements using ¹⁵O-labeled water.
Results: The fit of experimental TACs of live condition showed there are three-components in the washout process for ¹¹C. The observed medium and slow decay rates of ¹¹C were 0.30 min-1 and 0.004 min-1, in respectively. The two components did match the experimental TAC of ¹⁵O. The observed medium and slow decay rates of ¹⁵O in brain were 0.98 min-1 and 0.01 min-1, in respectively. The medium decay rate was relevant to CBF.
Conclusion: The difference of washout speed in the carbon beams and the oxgeon beam was observed. The chemical form of compounds with positron emitters is important for washout modeling. The data which helps to specify chemical form of compounds was obtained in this study.
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