Imaging of radiocesium uptake dynamics in a plant body using a newly-developed high-resolution gamma camera for radiocesium

Kawachi, Naoki; Yin, Y.-G.; Suzui, Nobuo; Ishii, Satomi; Yoshihara, Toshihiro*; Watabe, Hiroshi*; Yamamoto, Seiichi*; Fujimaki, Shu

We newly developed a gamma camera specific for plant nutritional research, and performed quantitative analyses on uptake and partitioning of radiocesium in intact plant bodies. A single-crystal scintillator, Ce-doped GAGG, was employed, which has a relatively high density, a large light output, no natural radioactivity and no hygroscopicity. A 44 44 matrix of the Ce:GAGG pixels, with dimensions of 0.85 mm 0.85 mm 10 mm for each pixel, was coupled to a high-quantum efficiency position sensitive photomultiplier tube. By using this gamma camera, soybean plants, grown in hydroponic solutions and fed with 1-2 MBq of Cs, were imaged for 6.5 days in maximum to investigate and visualize the uptake dynamics into/within the aerial part. As a result, radiocesium gradually appeared in the shoot several hours after feeding of Cs, and then accumulated intensively in the maturing pods and seeds in a characteristic pattern. Our results also demonstrated that this gamma-camera method enables quantitative evaluation of plant ability to absorb, transport, and accumulate radiocesium under various experimental conditions.