PET is a non-invasive imaging technique that uses radioactivity emitted from injected tracer chemicals to measure and image biological activity.
PET是一项非损伤的成像技术，它将示踪迹注入血液利用其放射性来检测生物活性并成像。
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This paper presents a determination method of specific activity for uranium isotope in rocks, soil, water and thorium isotope in rocks using 232u as a tracer isotope.