In-vivo imaging of a mouse by detecting bremsstrahlung X-rays from 14C using a La-GPS imaging system

Imaging of ¹⁴C outside of the subject is considered to be difficult because it is a radionuclide that emits only low-energy beta particles. However, we found that bremsstrahlung X-rays form ¹⁴C could be imaged from outside of subjects and is thus applicable to in vivo small animal imaging. We developed a high-resolution low-energy X-ray imaging system using a (Gd, La)₂Si2O₇:Ce(La-GPS) plate combined with a flat panel photomultiplier tube (FP-PMT) for in vivo imaging of a mouse to detect the X-rays from a ¹⁴C solution administered. Without using a parallel hole collimator, accumulated ¹⁴C in the mouse’s abdomen was imaged in 1 min and dynamic in vivo imaging was possible although the spatial resolution was moderate. With a parallel hole collimator, ¹⁴C in the abdomen was obtained with a higher spatial resolution with a 60-min acquisition time. We conclude that in vivo imaging of ¹⁴C is possible by using the developed high-resolution La-GPS imaging system and may be promising for molecular imaging research.