Gamma-ray inspection of rotating object

We develop a method to diagnose two-dimensional distribution of positron-emitting radioactivity in a rotating object through γ-ray coincidence measurements with two detectors. The principle of this method is same as PET but the measurement system is much simpler. We have constructed a prototype and performed tests with point-like and plate-shaped radioactive sources. The image reconstruction with ML-EM algorithm reproduced the distribution. It can be useful for radiotracer measurements of slow transport processes of materials in a closed system and can find applications in mechanical engineering.