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

Abstract

We developed a new gamma camera specifically for plant nutritional research and successfully performed live imaging of the uptake and partitioning of (137)Cs in intact plants. The gamma camera was specially designed for high-energy gamma photons from (137)Cs (662 keV). To obtain reliable images, a pinhole collimator made of tungsten heavy alloy was used to reduce penetration and scattering of gamma photons. A single-crystal scintillator, Ce-doped Gd3Al2Ga3O12, with high sensitivity, no natural radioactivity, and no hygroscopicity was used. The array block of the 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(-1) MBq(-1) for (137)Cs with an energy window from 600 keV to 730 keV, 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 (137)Cs for 6 days to visualize and investigate the transport dynamics in aerial plant parts. (137)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.

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Imaging of photoassimilates transport in plant tissues by positron emission tomography

“…In this way, non-invasive imaging methods that analyze the photoassimilates transport and allocation in plants on appropriate spatial and temporal scales can play an important role. It is generally known and accepted that radiotracer imaging is one of the few methods that enable to study and analyze the dynamics of substances in a living plant body, without sampling or fixation of plant tissues (Kawachi et al 2016). One of these radiotracer imaging systems and approaches is positron emission tomography (PET).…”

Recent Advances in Radioisotope Imaging Technology for Plant Science Research in Japan

“…In our scheme, the spatial resolution of the pinhole-type gamma camera for 137 Cs was nearly several centimeters. Imaging experiments targeting soybeans revealed distribution patterns such as a slow transition rate, as opposed to the vessel flow and accumulation, at specific sites during the growth period [36]. image of radioactive cesium ( Figure 5).…”