Imaging of radiocesium uptake dynamics in a plant body by using a newly developed high-resolution gamma camera
高解像度ガンマカメラを用いた植物体内における放射性セシウムの動態イメージング
河地 有木; 尹 永根; 鈴井 伸郎; 石井 里美; 吉原 利一*; 渡部 浩司*; 山本 誠一*; 藤巻 秀
Kawachi, Naoki; Yin, Y.-G.; Suzui, Nobuo; Ishii, Satomi; Yoshihara, Toshihiro*; Watabe, Hiroshi*; Yamamoto, Seiichi*; Fujimaki, Shu
We developed a new gamma camera specifically for plant nutritional research and successfully performed live imaging of the uptake and partitioning of
Cs in intact plants. The gamma camera was specially designed for high-energy
photons from
Cs (662 keV). To obtain reliable images, a pinhole collimator made of tungsten heavy alloy was used to reduce penetration and scattering of
photons. The array block of the GAGG scintillator was coupled to a high-quantum efficiency position sensitive photomultiplier tube to obtain accurate images. The completed gamma camera had a sensitivity of 0.83 count s
MBq
for
Cs, and a spatial resolution of 23.5 mm. We used this gamma camera to study soybean plants that were hydroponically grown and fed with 2.0 MBq of
Cs for 6 days to visualize and investigate the transport dynamics in aerial plant parts.
Cs gradually appeared in the shoot several hours after feeding, and then accumulated preferentially and intensively in growing pods and seeds; very little accumulation was observed in mature leaves. Our results also suggested that this gamma-camera method may serve as a practical analyzing tool for breeding crops and improving cultivation techniques resulting in low accumulation of radiocesium into the consumable parts of plants.