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。

youdao

The placebo group showed a slight increase of activity up to the 5th day. Only then radioactivity began to decline.

而安慰剂组直至试验的第五天放射活性仍有轻微的增加，从那以后放射活性才开始下降。

youdao

An activity metering unit (9) is operable to determine a level of radioactivity in a metering section (8) of the fluid delivery path downstream from the valve means (V1).

放射性测量装置(9)可操作以确定所述阀装置(V 1)下游的所述流体输送管道的测量部分(8)的放射性级别。

youdao